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GLERL Publication Abstracts: FY 2002
Publications List Key |
Capitalized names represent GLERL authors. |
* = Not available from GLERL. |
** = Available in GLERL Library only. |
AGY, M. A. Changes in the nearshore and offshore zooplankton communities
of southeastern Lake Michigan. Master’s Thesis, University of Michigan,
School of Natural Resources and Environment, Ann Arbor, MI, 52 pp. (2001).
http://www.glerl.noaa.gov/pubs/fulltext/2001/20010016.pdf
Zooplankton populations in southeastern Lake Michigan were analyzed across both space and time by examining nearshore to offshore collections on approximately a monthly basis from 1998through 2000. Zooplankton density and biomass were significantly different among sites during all seasons, with differences more prevalent during spring and summer. Twice during the study, there was an increase in the proportion of small-bodied zooplankton. In fall 1998, there was a decrease in calanoid populations and subsequent replacement by smaller-bodied cyclopoids. Specifically, the number of Diaptomus ashlandi declined by over 50% between winter 1998 and winter 1999 at all sites. Changes
in calanoid populations coincided with a strong year-class of alewives in 1998. A shift to smaller species of Ciadocera also occurred at both of the deeper sites between 1999 and 2000. In summer 2000, the smaller Bosmina longirostris exhibited a two-fold increase in abundance relative to 1999, and Daphnia galeata mendotae decreased from over 2400 x m-3 in summer 1999 to less than 200 x m-3 in 2000. Both the low densities of Daphnia and the inshore-offshore patterns of cladocerans observed in this study were consistent with sizeselective predation by fish. A comparison between 1998-2000 data with 1970s data showed significant decreases in zooplankton density and biomass in southeastern Lake Michigan. In summer and fall, zooplankton biomass was three to five times lower in the nearshore region during 1998-2000 relative to the 1970s and two to four times lower in the mid-depth region. Decreases were most likely due to reduced food availability caused by declines in both phosphorus concentrations and phytoplankton abundance nearshore. Predation and competition from exotic species may have also been responsible for longterm changes in zooplankton populations.
ASSEL, R. A., and L. R. HERCHE. Coherence of long-term lake ice records.
Verh. Internat. Verein. Limnol. 27:2789-2792 (2000).
Lake ice records are important in studies of climate (Assel and Robertson
1995) and aquatic ecosystems (Magnuson et al. 1997). Further analysis
of historical lake ice records is needed to improve knowledge of global
cryospheric trends (Fitzharris 1996). An International workshop on Lake
Ice and Climate was held at the University of Wisconsin in 1996 (Magnuson
et al. 2000) with the general goal of establishing a lake ice database
and using it to analyze and interpret long-term ice data for their climatic
and ecological content. The analysis described here is made under the
auspices of an international "Lake Ice analysis Group" (LIG) established
at that workshop. In this paper we present a preliminary analysis of
1) variations of long-term average ice-on, ice-off, and ice duration
with latitude, and 2) an index of the coherence of ice event dates among
five sites over the Northern Hemisphere with relatively continuous records
from 1850 to 1995. Our objective is to provide information useful for
the assessment and analysis of climate variability, cl imate change,
and aquatic systems.
ASSEL, R. A., D. C. NORTON, and K. C. CRONK. A Great Lakes ice cover
digital data set for winters 1973-2000. NOAA Technical Memorandum GLERL-121,
Great Lakes Environmental Research Laboratory, Ann Arbor, MI, 45 pp. (2002).
ftp://ftp.glerl.noaa.gov/publications/tech_reports/glerl-121
A 28-winter digital ice cover data set consisting of 1122 ice charts
was established for the Great Lakes. Data reduction and quality control
procedures are described in Norton et al. (2000). The data are available
in ARC/INFO export and ASCII grid formats. Three types of ice attribute
data are given: ice concentration class (the fraction of a unit of surface
area covered by ice), ice stage class (range of ice thicknesses), and
ice form class (size of ice floes). Ice attribute data coding conventions
are described and discussed. The temporal and spatial distribution of
the ice chart dates and ice attribute data are summarized in a table
and in graphs. Metadata is provided as appendices.
BELETSKY, D. Modeling wind-driven circulation in Lake Ladoga. Boreal
Environment Research 6:307-316 (2001). http://www.glerl.noaa.gov/pubs/fulltext/2001/20010015.pdf
The goal of this paper is to present circulation patterns in Lake Ladoga
occurring during episodes of strong wind. Hydrodynamics of episodic
events are studied with a three-dimensional barotropic numerical model.
Model results are presented for a variety of wind directions and, therefore,
can be used for analysis of various biogeochemical data. As an illustration,
an analysis of sediment distribution in Lake Ladoga is presented. It
is suggested that location of maximum sediment deposition in southeastern
Lake Ladoga is due to sediment transport during episodes of strong northwesterly
winds. These events generate significant waves in southern Lake Ladoga,
causing sedment resuspension and subsequent offshore advection and dsposition.
Bogdan, J. J., J. W. Budd, B. J. EADIE, and K. C. Hornbuckle. The effect
of a large resuspension event in southern Lake Michigan on the short-term
cycling of organic contaminants. Journal of Great Lakes Research
28(3):338-351 (2002).
In January and March, 1998, a series of intense, northerly wind-driven
storms suspended sediment over the entire coastline of the southern
basin of Lake Michigan. The effect of large scale resuspension on organic
contaminant cycling was investigated using a two-pronged sample collection
strategy that included analysis of settling sediment trap material and
discrete air and water samples collected before and after a major resuspension
event. It was found that major resuspension events result in a large
flux of contaminants. For example, 6.2 ng/cm2 …PCB (sum of 89 congener
peaks) and 175 ng/cm2 …PAHs (sum of 31 compounds) fell through the water
column in the southern basin between November and May but almost half
of that occurred in the month of March after a series of intense storms
induced a large-scale resuspension event in that month. Assuming the
concentration of contaminants in settling sediments is similar throughout
the basin, the March event brought ~400 kg of …PCBs and -13,000 kg PAHs
into the water column. Furthermore, the data indicate that concentrations
of dissolved phase PCB and …PAHs declined significantly (_ = 0.05) after
the event and after resuspended sediment had settled from the surface
waters. As a result of the depressed dissolved concentrations at the
surface, the potential for gas-phase input to the lake increases on
the southwestern coastal region near Chicago, IL and Gary, IN. The potential
input of gas-phase contaminants was 8 kg for …PCBs and 2,200 kg for
…PAHs over the 40-day lifetime of the nearshore event.
BRANDT, S. B., D. M. MASON, M. J. McCORMICK, B. M. LOFGREN, T. S. HUNTER,
and J. A. TYLER. Climate change: implications for fish growth performance
in the Great Lakes. American Fisheries Society Symposium 32:61-76
(2002).
Climate change will alter the thermal regime in the Great Lakes, including
the onset, duration, and structure of thermal stratification. Such changes
may, in turn, affect spatial distributions of planktivores, rates of
food web interactions, and growth rate potential of fishes. We use predicted
changes in water temperatures for the years 2030 and 2090 to evaluate
growth rate potential of lake trout Salvelinus namaycush, chinook
salmon Oncorhynchus tshawytscha, and striped bass Morone saxatilis
in Lake Michigan. Changes in the timing and extent of thermal stratification
changed the predicted distributions of prey fish and the spatio-temporal
patterns of growth potential. Overall, growth rate potential of all
piscivores increased under climate warming simulations. For chinook
salmon, an assumed 15% reduction of prey abundances reduced mean growth
rate potential by 9%. A comparison of measured temperatures for 1996
and 1998 showed that current warm years (1998) are similar to mean conditions
predicted between years 2030 and 2090. We suggest that studies of interannual
variations in food web dynamics may provide insights into the potential
impact of climate on fishes.
Bundy, M. H., and H. A. VANDERPLOEG. Detection and capture of inert particles
by calanoid copepods: the role of the feeding current. Journal of Plankton
Research 24(3):215-223 (2002).
Although there is a scarcity of supporting empirical evidence, it has
long been suspected that calanoid copepods use mechanoreception to detect
the presence and location of potential prey items entrained in the feeding
current. In this study, we document the first observations showing a
freely swimming calanoid copepod, Skistodiaptomus oregonensis,
attacking prey-sized, non-motile, inert particles entrained in the feeding
current before the particles contact the copepod's sensory appendages.
Feeding current geometry, fluid velocities and associated behaviours
that characterize these interactions are described. The results of this
study show how copepod swimming behaviour, coupled with a low-velocity
feeding current, not only increases copepod encounter rates with inert
prey by increasing direct contact rates, but also increases the probability
of detecting and capturing remotely located prey that have well-developed
escape responses. In turbulent regimes, a far-reaching, low-velocity
feeding current should increase encounter rates, but only if coupled
with behaviours that quickly minimize separation distances once prey
is detected.
Carrick, H. J., A. Padmanabha, L. Weaver, G. L. FAHNENSTIEL, and C. R.
Goldman. Importance of the microbial food web in large lakes (USA). Verh.
Internat. Verin. Limnol. 27:3170-3175 (2000).
The traditional view of food web structure categorizes all organisms
within an ecosystem into one of several feeding guilds (i.e. primary
producers, decomposers, herbivores, and consumers), where energy is
transferred from one guild to the next (Lindeman 1942). The biomass
of these guilds decreases geometrically with successive trophic levels
to form a pyramid, with a large biomass of plants at the base (Elton
1927). Metabolic inefficiencies, such as excretion and sloppy feeding,
produce significant losses at each trophic level, with the greatest
loss at the highest trophic level (Rich & Wetzel 1978). Deviations from
this paradigm have been described for planktonic communities in the
ocean, where the biomass of heterotrophic organisms can rival phytoplankton,
thus indicating a tight coupling between plants and animals (e.g. Odum
1971). However, our view of food web structure in aquatic ecosystems
is being further revised based upon the knowledge that small heterotrophic
organisms are more quantitatively important than previously thought
(Azam et al. 1983). Recent technological advances now allow more accurate
censusing of natural microbial populations, as well as measurement of
their high rates of metabolic activity (Kemp et al. 1993). Furthermore,
large concentrations of non-living pools of organic carbon and detritus
are common features of aquatic ecosystems, and appear to be responsible
for fueling a portion of this high microbial metabolic activity (e.g.
Ducklow 1994). In this way, organic wastes produced at all levels of
the food chain are available to support significant levels of heterotrophic
production, that can often rival rates of primary production (e.g. Scavia
1988).
CARTER, G. S. Environmental assessment of the benthic macroinvertebrate
community of Muskegon Lake, MI 1999 and evaluation of changes since 1972.
Masters Thesis, University of Michigan, School of Natural Resources and
Environment, Ann Arbor, MI, 67 pp. (2002).
Benthic macroinvertebrate community composition is widely considered
an effective tool for evaluating environmental conditions. In fall 1999,
27 sites were sampled for benthic macroinvertebrates to assess the habitat
quality of Muskegon Lake, a drowned river mouth lake connected to eastern
Lake Michigan. The oligochaete-based, trophic condition index indicated
the lake was meso-eutrophic to eutrophic, and the community was largely
dominated by Aulodriluspigueti and Quistadrilus multisetosus.
Cluster analysis of the benthic community was used to assess distributions
relative to known areas of environmental degradation; four groups of
sites were discriminated. The site group closest to the river (the southeastern
end of the lake) consisted of several species indicative of enriched
conditions, likely due to its proximity to the river. The two site groups
on the western end were similar in community composition and reflected
similarities in depth. Despite similarities, the western-most group
had relatively higher mean densities for total benthos, oligochaetes,
total Aulodrilus spp., A. pigueti, Gammarus sp.,
chironomids, and Chironomus sp. than the more central group in
the western part of the lake; suggesting the western group may be more
productive. The community at the HA site group (central eastern area
near the southern shore) indicated better environmental conditions existed
at these sites than the other three groups; however, heavy-metal toxicity
was found that might have affected benthic composition. Comparisons
between benthic communities in 1972 and 1999 indicated broad changes
in the community and environmental conditions since diversion of wastewater,
which began in 1973. Increases in total benthos, oligochaetes, chironomids,
Gammarus sp., and Pisidium sp., coupled with increased
Shannon-Weaver diversity, number of taxa, and decreased proportion of
oligochaetes, were indicative of generally improved environmental conditions.
Changes in the benthic community likely reflected the diversion of wastewater
rather than colonization of the lake by Dreissena polymorpha.
Chen, C., R. Ji, D. J. SCHWAB, D. BELETSKY, G. L. FAHNENSTIEL, M. Jiang,
T. H. JOHENGEN, H. A. VANDERPLOEG, B. J. EADIE, J. W. Budd, M. H. Bundy,
W. Gardner, J. Cotner, and P. Lavrentyev. A model study of the coupled
biological and physical dynamics in Lake Michigan. Ecological Modeling
152:145-168 (2002). http://www.glerl.noaa.gov/pubs/fulltext/2002/20020002.pdf
A coupled physical and biological model was developed for Lake Michigan.
The physical model was the Princeton ocean model (POM) driven directly
by observed winds and net surface heat flux. The biological model was
an eight-component, phosphorus-limited, lower trophic level food web
model, which included phosphate and silicate for nutrients, diatoms
and non-diatoms for dominant phytoplankton species, copepods and protozoa
for dominant zooplankton species, bacteria and detritus. Driven by observed
meteorological forcings, a 1-D modeling eeriment showed a controlling
of physical processes on the seasonal variation of biological variables
in Lake Michigan: diatoms grew significantly in the subsurface region
in early summer as stratification developed and then decayed rapidly
in the surface mixed layer when silicate supplied from the deep stratified
region was reduced as a result of the formation of the thermocline.
The non-diatoms subsequently grew in mid and late summer under a limited-phosphate
environment and then declined in the fall and winter as a result of
the nutrient consumption in the upper eutrophic layer, limitation of
nutrients supplied from the deep region and meteorological cooling and
wind mixing. The flux estimates suggested that the microbial loop had
a significant contribution in the growth of microzooplankton and hence,
to the lower-trophic level food web system. The model results agreed
with observations, suggesting that the model was robust to capture the
basic seasonal variation of the ecosystem in Lake Michigan.
CROLEY, T. E. II. Evaluation of NOAA climate outlooks in extended Great
Lakes water levels forecast. Proceedings, Conference on Water Resources
Planning and Management, Roanoke, VA, May 19-22, 2002. Environmental Water
Resources Institute, American Society of Civil Engineers, Washington,
DC, 10 pp. (2002). http://www.glerl.noaa.gov/pubs/fulltext/2002/20020006.pdf
The Great Lakes Environmental Research Laboratory (GLERL) simulates
time series of daily Great Lakes hydrology by first estimating initial
hydrological conditions and then using a daily meteorology time series
(scenario) taken from the historical record. They do this to make a
deterministic hydrology "forecast" (including lake levels) from a representative
meteorology scenario. GLERL repeats this for other segments of the historical
record in an "operational hydrology" or "ensemble" approach in their
Advanced Hydrologic Prediction System (AHPS). The resulting set of lake
level scenarios serves as a statistical "sample" for inferring probabilistic
lake levels outlooks that properly consider antecedent hydrological
conditions. GLERL does this every day to produce six-month outlooks.
Meanwhile, the National Oceanic and Atmospheric Administration's Climate
Prediction Center publishes each month multiple long-lead probabilistic
meteorology outlooks. GLERL transforms these meteorological outlooks
into equations for sample weights and solves them simultaneoisly. Their
AHPS methodology weights their samples of six-month lake levels scenarios
each day to include the effects of these meteorology predictions. GLERL
simulated both deterministic and probabilistic lake level outlooks over
1995-2000 without the use of antecedent conditions or meteorology predictions
and then added them into the simulation to assess the value of each
in making the forecast.
CROLEY, T. E. II. Large basin runoff model. Chapter 17. In Mathematical
Models of Large Watershed Hydrology, V. Singh, D. Frevert and S. Meyer
Eds., Water Resources Publications, Highlands Ranch, CO, pp. 717-770 (2002).
Large-scale watershed models are required to estimate basin runoff
to the Great Lakes and other large-basin applications for use in long-term
routing determinations, water resource operation decisions, operational
hydrology studies, and long-term forecasting. Data availability over
large areas, large-basin applicability, computation requirements, and
model application costs often preclude the use of detailed watershed
models, designed for small scales, for large-scale applications. An
interdependent tank-cascade model is described that uses a mass balance
coupled with linear reservoir concepts. It is physically based and uses
climatological considerations not possible for small watersheds; analytical
solutions are employed to bypass numerical inaccuracies. Snowmelt and
net supply computations are separable from the mass balance determinations
and are based on simple degree-day empiricism. Partial area concepts
are used to determine infiltration and surface runoff. Losses are determined
from joint consideration of available energy for actual and potential
evapotranspiration and of available moisture in the soil horizons by
using climatological concepts. Heuristic calibration procedures are
described that give insight into the use of the model. The model is
applied in example watersheds and it and its calibration are evaluated.
Source code, executable programs, and all examples are available in
appendices and over the World Wide Web.
CROLEY, T. E. II, and R. A. ASSEL. Great Lakes evaporation model sensitivities
and errors. Proceedings, Second Federal Interagency Hydrologic Modeling
Conference, Subcommittee on Hydrology of the Interagency Advisory Committee
on Water Data, Las Vegas, NV, July 28-August 1, 2002. 12 pp. (2002). http://www.glerl.noaa.gov/pubs/fulltext/2002/20020004.pdf
The Great Lakes Environmental Research Laboratory developed a lumped-parameter
model of evaporation and thermodynamic fluxes for the Great Lakes (Croley,
1994). It is based on a point energy balance at the lake's surface (Croley,
1989) and on a one-dimensional (vertical) superposition of lake heat
storage (Croley,1992). Ice formation and loss is coupled also to lake
thermodynamics and heat stroage (Croley and Assel, 1994). The model
is calibrated to observed daily water surface temperatures and ice cover
to apply it in a particular setting. Initialization of the model corresponds
to identifying water surface temperature, heat storage, and ice cover
from field conditions or from previous model runs. The model is used
with boundary meteorology conditions (daily time series of air temperature,
wind speed, cloud cover, and humiidy) to simulate heat storage and water
temperature profiles in a lake from initial conditions forward.
CROLEY, T. E. II, and C. He. Great Lakes large basin runoff model. Proceedings,
Second Federal Interagency Hydrologic Modeling Conference, Subcommittee
on Hydrology of the Interagency Advisory Committee on Water Data, Las
Vegas, NV, July 28-August 1, 2002. 12 pp. (2002). http://www.glerl.noaa.gov/pubs/fulltext/2002/20020005.pdf
Agencies concerned with managing water resources of large watersheds,
particularly over large time intervals, must be able to assess expected
hydrology of an area. Large-scale watershed models are required to estimate
basin runoff to the Great Lakes for use in long-term routing determinations,
water resource operation decisions, operational hydrology studies, and
long-term forecasting. These models must be designed as continuous-time
flow representations for assessing water resource questions over the
long term (as opposed to flood prediction over the short term). The
models must satisfy limited-data requirements, mandated by data availability
for large areas such as the Great Lake basins. Allowable data inputs
are limited to daily precipitation and air temperature. Also allowed
are any data that can be abstracted easily from available maps or climatic
summaries. Model concepts must be physically based, so that understanding
of watershed response to natural forces is facilitated, and so the models
are economical to use. The Great Lakes Environmental Research Laboratory
(GLERL) built its Large Basin Runoff Model (LBRM) for modeling river
systems 'within the Laurentian Great Lakes Basin. This inter-dependent
tank-cascade model is a lumped-parameter model of runoff at the mouth
of a water-shed and has been tested on the 121 watersheds of the Great
Lakes. It was developed from large-scale (climatological) concepts and
designed for weekly or monthly volumes of runoff. The model consists
of water and heat balances, as do other water-budgeting models, but
with alternative physical interpretations given to its components. The
model is physically based and uses climatological considerations not
possible with small watersheds. In particular, evapotranspiration losses
for large areas may now be considered as a function of readily available
data. Analytical solutions are used instead of numerical solutions to
bypass associated numerical error. The model is described and applied
in an example watershed.
EADIE, B. J., D. J. SCHWAB, T. H. JOHENGEN, P. J. LAVRENTYEV, G. S. MILLER,
R. E. Holland, G. A. LESHKEVICH, M. B. LANSING, N. R. MOREHEAD, J. A.
ROBBINS, N. HAWLEY, D. N. Edgington, and P. L. VAN HOOF. Particle transport,
nutrient cycling, and algal community structure associated with a major
winter-spring sediment resuspension event in southern Lake Michigan. Journal
of Great Lakes Research 28(3):324-337 (2002).
Over the past decade, intermittent satellite imagery revealed the presence
of an extensive plume of resuspended sediments in late winter-early
spring with a clear offshore projection coinciding with the region of
maximum sediment accumulation in the lake. The large scale of the plume
implied that this process was important in sediment, and associated
constituent, cycling and transport, but it had never been sampled due
to severe conditions. The onset of the 1996 event coincided with a major
March storm. Within a few days the plume was approximately, 10 km wide
and over 300 km in length, implying that the source of the reflective
materials was widely distributed. An estimate of the total mass of resuspended
sediment, 12 days after the storm, was similar to the annual external
load of (sand-free) particulate material to the southern basin. The
high turbidity plume persisted for over a month, progressing northward
along the eastern shore with a major offshore transport feature. Sediment
traps within this feature recorded a major mass flux event. The plume
was sampled on two occasions and was found to contain 5 to 10 times
as much suspended matter as open-lake locations outside the visible
plume. Total particulate phosphorus was high within the plume making
this episodic process important in sediment-water exchange. The diatom
community structure within the plume was significantly different from
outside the plume and was characteristic of more eutrophic waters. Abundance
of non-diatom phytoplankton and microbial food web organisms were highest
at the plume edge. The episodic nature of this process makes it difficult
to sample, but the scale makes it important in designing monitoring
programs and mass-balance modeling efforts.
Fritz, H. M., and P. C. LIU. An application of wavelet transform analysis
to landslide-generated impulse waves. Proceedings, Fourth International
Symposium Waves 2001, San Francisco, CA, September 2-6, 2001. American
Society of Civil Engineers, pp. 1477-1486 (2001).
This paper presents an analysis of applying continuous wavelet transform
spectrumanalysis to the results of laboratory measurement of landslide-generated
impulse waves. As the measured results are understandably unsteady,
nonlinear, and non-stationary, the application of time-localized wavelet
transform analysis is shown to be a suitable as well as useful approach.
the analysis on correlating the time-frequency wavelet spectrum configurations
in connection with the ambient parameters that drive the impulse wave
process, with respect to time and space, leads to interesting and stimulating
insights not previously known.
GREAT LAKES ENVIRONMENTAL RESEARCH LABORATORY. Aquatic Invasive Species
(AIS) and the Great Lakes: Simple Questions, Complex Answers. NOAA, Great
Lakes Environmental Research Laboratory, Ann Arbor, MI, 2 pp. (2002).
http://www.glerl.noaa.gov/pubs/brochures/
GREAT LAKES ENVIRONMENTAL RESEARCH LABORATORY. Exotic, invasive, alien,
nonindigenous, or nuisance species: No matter what you call them, they're
a growing problem. NOAA, Great Lakes Environmental Research Laboratory,
Ann Arbor, MI, 2 pp. (2002). http://www.glerl.noaa.gov/pubs/brochures/
Human activities are profoundly affecting the earth's surface. Human
population growth has been accompanied by a variety of stresses on natural
ecosystems, including the unintentional introduction of various nonindigenous
invasive species.
GREAT LAKES ENVIRONMENTAL RESEARCH LABORATORY. Met Stations and Web Cams.
NOAA, Great Lakes Environmental Research Laboratory, Ann Arbor, MI, 2
pp. (2002). http://www.glerl.noaa.gov/pubs/brochures/
GREAT LAKES ENVIRONMENTAL RESEARCH LABORATORY. Selected projects of GLERL's
Marine Instrumentation Laboratory. NOAA, Great Lakes Environmental Research
Laboratory, Ann Arbor, MI, 2 pp. (2002). http://www.glerl.noaa.gov/pubs/brochures/
The Plankton Survey System, Lake Michigan Wireless Environmental Observatory,
and the Sequential Sediment Sampler are described.
Hancock, G., D. N. Edgington, J. A. ROBBINS, J. N. Smith, G. Brunskill,
and J. Pfitzner. Workshop on radiological techniques in sedimentation
studies: methods and applications. In Environmental Changes and Radioactive
Tracers. Proceedings of the South Pacific Environmental Radioactivity
Association (SPERA) 2002, J.M. Fernandez and R. Fichez (Eds.), IRD Editions,
Paris, France, pp. 232-251 (2002). http://www.glerl.noaa.gov/pubs/fulltext/2002/20020014.pdf
The following document summarizes the important issues raised during
the 3 hour discussion period of the Workshop on "Radiological Techniques
in Sedimentation Studies", held on June 22, 2000. The document includes
contributions from the above authors summarizing, and in some cases
illustrating important features of the discussion. The discussion issues
covered: (1) problems associated with the use of "mapping" algorithms,
particulary CRS, to give unsubstantiated 210PB "dates", (2) the necessity
to validate 210Pb deposition histories, (3) the trend in research jourjnals
to publish 210Pb chronologies with supporting data, (4) the effect of
drainagae basin residence times on fallout nuclide sediment profiles,
and (5) the low activity of fallout tracers in the southern hemisphere,
and the implications for sample core collection, analysis, and geochronological
usage.
He, C., and T. E. CROLEY II. A development framework for two-dimensional
large basin operational hydrologic models. Proceedings, Second Federal
Interagency Hydrologic Modeling Conference, subcommittee on Hydrology
of the Interagency Advisory Committee on Water Data, Las Vegas, NV, July
28-August 1, 2002. 12 pp. (2002). http://www.glerl.noaa.gov/pubs/fulltext/2002/20020007.pdf
Large-scale operational hydrologic models ae essential tools in support
of multiple water resource applications such as flood control, navigation,
irrigation,and habitat management, etc. at the regional or continental
scales. These models, unlike micro scale watershed models, are defined
over large area (>103 km2) and long time scales (typically for use over
monthly and annual or longer time scales at a daily interval). Often
constrained by l imited data availability, computational requirements,and
model application costs over larger areas, large-scale models must have
few parameters, use easily accessible meteorolgic and hydrologic databases,
and be user-friendly. Horberger and Bioyer (1995) found that better
representation of spatial and temporall variability and appropriate
parameterization of hydrologic processes have become critical in recent
years. They reviewed recent advances in watershed modeling pertinent
to use of Geographic Information Systems (GIS), remotely sensed data,
and environmental tracers for micro scale modeling. This paper addresses
the needs and challenges of large-scale operational hydrologic models
through the development of a modeling framework. It focuses on advances
in parameterization of the infiltration and evapotranspiration processes
and onthe representation of large-scale spatial variability.
Holcombe, T. L., J. S. Warren, D. F. REID, W. T. Virden, and D. L. Divins.
Small rimmed depression in Lake Ontario: An impact crater? Journal
of Great Lakes Research 27(4):510-517 (2001).
Detailed bathymetry of Lake Ontario reveals a small circular feature
and adjoining SW-trending ridge associated with a small topographic
high identified as Charity Shoal on nautical charts. The feature consists
of a circular basin 1,000 m in diameter and 19+ m deep, completely surrounded
by a low-relief rim that rises to within 5 m of the water surface over
much of its extent. A N53E tapering ridge is contiguous with the feature
and extends southwestward. Bedrock consists of middle Ordovician limestones
100-150 m thick overlying rocks of Precambrian age. The limited information
available suggests that the feature may be an extraterrestrial impact
crater, but other origins such as sinkhole, volcanic cone, or kettle,
are not ruled out. Time of formation is not known, but likely times
include the Pleistocene when the area was exposed by glacial erosion,
the middle Ordovician near the time of deposition of limestones, or
the Cambro-Ordovician or Precambrian when erosion surfaces of this age
were exposed. A subtle negative magnetic anomaly coincides with the
feature and is consistent with an impact origin, though not positively
diagnostic. Relief of the feature is low compared to that typical of
an impact crater of this size. Glaciation may have diminished relief
by eroding the rim and filling the central basin with drift. Verification
as an impact crater will require detailed geophysical surveys and collection
and analyses of samples from in and around the structure.
Holmes, C. W., J. A. ROBBINS, R. Halley, M. Bothner, M. Ten Brink, and
M. Marot. Sediment dynamics of Florida Bay mud banks on a decadal time
scale. Bulletins of American Paleontology 361:31-40 (2001).
Ecosystem management requires knowledge of environmental dynamics.
If historical environmental records do not exist, other methods must
be employed to obtain this information. A well-known geochemical procedure
that supplies this type of data is the use of natural radioactive nuclides
to "date" the timing of events. Of the many naturally occurring nuclides,
210Pb is the best suited for gauging the timing of episodes in Florida
Bay. The age-depth relationships were calculated using the 210Pb method
for thirty-five sites within Florida Bay. The ages were independently
confirmed by comparing the distribution of known concentrations of atmospherically
anthropogenic lead recorded in dated cores to similar data in an annually
banded coral. Sediments in the western and northern fringe of Florida
Bay are accumulating at ~0.3 cm/yr. a rate similar to that of sea level
rise. In the north-central part of the bay, sediments are accumulating
at a taster rate of ~1.0 cm/yr. The highest rate, >=2.0 cm/yr was measured
in the northeastern pan of the bay on the bank between Pass and Lake
Keys. The rapid rate of accumulation in the northeastern pan of the
bay permits the deciphering of biological and geochemical changes with
an accuracy of about two years. In contrast. the intermediate sediment
rate in the central pan of the bay provides adequate age-depth for relationships
deciphering the environmental record of the past 100 years.
Ji, R., C. Chen, J. W. Budd, D. J. SCHWAB, D. BELETSKY, G. L. FAHNENSTIEL,
T. H. JOHENGEN, H. A. VANDERPLOEG, B. J. EADIE, J. Cotner, W. Gardner,
and M. Bundy. Influences of suspended sediments on the ecosystem in Lake
Michigan: A 3-D coupled bio-physical modeling experiment. Ecological
Modeling 152:169-190 (2002). http://www.glerl.noaa.gov/pubs/fulltext/2002/20020003.pdf
The influence of suspended sediments on the Lake Michigan ecosystem
was examined using a 3-dimensional (3-D) coupled biological and physical
model developed by Chen et al. (part I). The model was driven by the
realistic meteorological forces observed in March 1998, with daily inputs
of suspended sediment concentration that were derived from temporally
and spatially interpolated satellite imagery. The model results show
the significant impact of a seasonally recurring coastal resuspension
plume on the spatial and temporal variation of the nutrients and plankton
in southern Lake Michigan. The plume-released nutrients played an essential
role in maintaining the nutrient level in the lake. Although the growth
of phytoplankton in the plume depended on the availability of nutrients
and light, the offshore decrease in phytoplankton biomass still satisfied
the Sverdrup's relationship. Cross-shore fluxes of nutrients and phytoplankton
were controlled by episodic wind events with a period of 5-7 days: offshore
during southward winds and onshore during northward winds. The flux
estimates for biological variables suggest that the microbial food web
is a key contributor to secondary production in southern Lake Michigan
and the lower trophic level food web system could be dynamically divided
into two decoupled loops: (1) detritus -bacteria-microzooplankton-large
zooplankton; and (2) nutrient-phytoplankton-detritus. The model-predicted
spatial distributions of nutrients and phytoplankton were in reasonable
agreement with observations taken during the 1998 EEGLE interdisciplinary
cruises, suggesting that the model was sufficiently robust to capture
the basic characteristics of the Lake Michigan ecosystem during the
plume event.
LANDRUM, P. F., M. L. GEDEON, G. A. Burton, M. S. Greenberg, and C. D.
Rowland. Biological responses of Lumbriculus variegatus exposed
to fluoranthene spiked sediment. Archives of Environmental Contamination
and Toxicology 42:292-302 (2002). http://www.glerl.noaa.gov/pubs/fulltext/2002/20020008.pdf
Lumbriculus variegatus was used as a bioassay organism to examine
the impact of the sediment-associated polycyclic aromatic hydrocarbon
(PAH) fluoranthene on behavior, reproduction, and toxicokinetics. The
number of worms increased between the beginning and end of the experiment
at 59 g g-1 fluoranthene, but at the next higher treatment (108 g g-1)
the number of worms found was lower and not different from the control.Worms
exposed to 95 g g-1 also exhibited increased reproduction when fed a
yeast-cerophyl-trout chow mixture. On a total biomass basis, only the
95 g g-1 exposure with food exhibited a statistically significant increase
over the nonfed control. Evaluation of reproduction at the two highest
treatments was compromised by a brief aeration failure 2 days before
the end of the experiment. The behavioral responses were followed as
changes in biological burial rate (sediment reworking rate) of a 137Cs-labeled
marker layer. The biological burial rate increased toward a plateau
as the concentration increased from the control (3.9 g g-1 dry weight
total PAH) to 355 g g-1 dry weight fluoranthene in sediment. The aeration
failure had minimal impact on the determination of reworking rate because
all the data for the rate determination were collected prior to the
aeration failure. Uptake and elimination rates declined with increasing
treatment concentration across the range of fluoranthene concentrations,
59-355 g g-1 dry weight sediment. The disconnect between the increasing
biological burial rates and the decreasing toxicokinetics rates with
increasing exposure concentration demonstrates that the toxicokinetic
processes are dominated by uptake and elimination to interstitial water.
The bioaccumulation factor (concentration in the organisms on a wet
weight basis divided by the concentration in sediment on a dry weight
basis) ranged from 0.92 to 1.88 on day 10 and declined to a range of
0.52 to 0.99 on day 28 with the lowest value at the highest dose.
LANDRUM, P. F., and J. P. Meador. Is the body residue a useful dose metric
for assessing toxicity? SETAC Globe May-June:32-34 (2002).
Clearly the toxicity of a compound depends on its concentration at
the receptor site and the duration of site occupation. Aquatic toxicology
made use of the concept that the dose at the receptor was proportional
to the concentration in the organism which was in turn found to be proportional
to the exposure concentrationwith aqueous exposures. The use of external
exposure media as the dose metric was severely challenged by the presence
of multiple routes of exposure and factors that alter contaminant bioavailability,
e.g. s ediment exposures. This suggestion that body residue would serve
as a useful dose metric was advocated by McCarty (1986) with the Critical
Body Residue (CBR) concept linked to the concentration to cause 50%
mortality in a population for non-polar, non-metabilized toxicants (McCarty
1990).
Lee, J.-H., P. F. LANDRUM, and C.-H. Koh. Prediction of time-dependent
PAH toxicity in Hyalella azteca using a damage assessment model.
Environmental Science and Technology 36:3131-3138 (2002).
A damage assessment model (DAM) was developed to describe and predict
the toxicity time course for PAH in Hyalella azteca. The DAM
assumes that death occurs when the cumulative damage reaches a critical
point and was described by a combination of both first-order toxicokinetic
and toxicodynamic models. In aqueous exposures, body residues increase
in proportion to the water concentration. Damage is assumed to accumulate
in proportion to the accumulated residue and damage recovery in proportion
to the cumulative damage when damage is reversible. As a result, the
toxicity time course, LC50(t), is determined by both a damage recovery
rate and an elimination rate. The constant critical body residue (CBR)
and the critical area under the curve (CAUC) models can be derived as
two extreme cases from the DAM, and all three models were reanalyzed
using a hazard modeling approach. As a result, the critical cumulative
damage (DL) is the determinant of the concentration-time response relationship
and not simply the CBR or the CAUC. Finally, from the DAM, two parameters,
a damage recovery rate constant kr and the killing rate k, were estimated
and found to be relatively constant for selected PAH.
Lee, J.-H., P. F. LANDRUM, and C.-H. Koh. Toxicokinetics and time-dependent
PAH toxicity in the amphipod Hyalella azteca. Environmental
Science and Technology 36:3124-3130 (2002).
The relationship between toxicokinetics and time-dependent PAH toxicity
to Hyalella azteca was examined to test the constant critical
body residue (CBR) model. A constant CBR model is based on the assumption
that the body residue for 50% mortality is constant for each PAH across
exposure times. With a constant CBR, kinetic parameters determined through
kinetic experiments would be similar to those estimated from time series
toxicity data. Time-dependent toxicity was investigated using three
types of data: time series LC50 data, LT50(c), and CBR values measured
at multiple exposure times for live and dead animals. Kinetic parameters
were measured independently. The constant CBR model did not predict
the PAH toxicity time course for H. azteca. Since a first-order
kinetic model predicted the bioaccumulation of the parent PAH except
for naphthalene, this result is not due to a failure to predict the
internal dose (body residue). The influence of metabolites on toxicity
was negligible except for naphthalene. The LC values at multiple exposure
times decreased to an incipient lethal concentration after H. azteca
reached steady state. Measured CBR values also decreased with increasing
exposure time. Thus, the time course of PAH toxicity is determined not
only bythe bioconcentration kinetics but also by the cumulative toxicity
with increasing exposure time. Therefore, time-to-death or hazard models
must be developed as a complement to toxicokinetic models to describe
and predict the toxicity time course.
LESHKEVICH, G. A., and S. V. Nghiem. The 2002 Great Lakes Winter Experiment
(GLAWEX 2002) three-dimensional mapping of the Great Lakes ice cover.
Proceedings, NASA AirSAR Workshop, Pasadena, CA, March 4-6, 2002. NASA
Jet Propulsion Laboratory, Pasadena, CA, 10 pp. (2002).
In his recommendations for Great Lakes ice research, (Marshall, 1966)
concludes that "studies are needed to classify Great Lakes ice types,
their distribution and drift during the winter, and the subtle changes
in albedo and imagery which mark the gradual disintegration of the ice
and the imminent breakup." Early investigations by various researchers
were conducted to classify and categorize ice types and features (Chase,
1972; Bryan, 1975), to map ice distribution (McMilan and Forsyth, 1976;
Leshkevich, 1976), and to monitor and attempt to forecast ice movement
with remotely sensed data (Strong, 1973; McGinnis and Schneider, 1978;
Rumer et al., 1979; Schneider et al., 1981). Most of the early research
on Great Lakes ice cover was done by visual interpretation of satellite
and other remotely sensed data (Rondy, 1971; Schertler et al., 1975;
Wartha, 1977). Because of the size and extent of the Great Lakes and
the variety of ice types found there, the timely and objective qualities
inherent in computer processing of satellite data make it well suited
for such studies. Moreover, the all-weather, day/night sensing capabilities
of Synthetic Aperture Radar (SAR) make it well suited to the short daylight,
cloud dominated winter conditions in the Great Lakes region.
LESHKEVICH, G. A., and S. V. Nghiem. Radar remote sensing of Great Lakes
ice cover. Proceedings, 2002 IEEE International Geoscience and Remote
Sensing Symposium and the 24th Canadian Symposium on Remote Sensing, Toronto,
Canada, June 24-28, 2002. Institute of Electrical and Electronics Engineers,
Inc., Piscataway, NJ, 1 pp. (2002). http://www.glerl.noaa.gov/pubs/fulltext/2002/20020009.pdf
Remote sensing of Great Lakes ice cover uses various classes of radars
including scatterometer, polarimetric synthetic Aperture Radar (SAR),
and interferometric SAR. Applications of radar mapping of Great Lakes
ice cover includes marine resource management, lake fisheries and ecosystem
studies, natural hazards such as ice jams and flooding, shipping and
hydropower industries, and Great Lakes climatology. Satellite wide-swath
scatterometers provide large areal coverage with high temporal resolution
data to map Great Lakes ice cover. They compliment the high spatial
but lower temporal resolution of satellite SAR data.
Lesht, B. M., and N. HAWLEY. Using wave statistics to drive a simple
sediment transport model. Proceedings of the Fourth International Symposium
on Waves 2001, San Francisco, CA, September 2-6, 2001. American Society
of Civil Engineers, pp. 1366-1375 (2001).
Because both contaminant and nutrient cycles in the Laurentian Great
Lakes depend on particle behavior and movement, sediment transport is
a critical component of many of the water quality models being developed
to understand and manage this important resource. To avoid complicated
models that cannot be supported by the available field data, we have
used observation-based, empirical analysis as the basis for developing
methods of predicting sediment resuspension from relatively simple measurements
of the surface wave field. Our modeling is based on data obtained from
instrumented tripods designed to measure near-bottom hydrodynamic and
sedimentological conditions for extended periods of time. Because of
the long duration of the deployments, it usually is impractical to both
sample and record the data at the high frequency that would be needed
to resolve the effects of individual surface waves. Instead, we have
used a system of burst sampling in which we sample the sensors at high
frequency during a period of time that is repeated at tn interval appropriate
for the deplyment duration. Rather than record the individual samples
during the burst, we record only statistics obtained from the individual
samples. Our results show that simple representations of the surface
wave field obtained from the burst statistics can be used to model sediment
transport in wave-dominated enviroments. We also show that once the
model parameters are determined, the forcing wave conditions can be
derived from other sources, including wind-driven wave models, with
comparable success.
Lesht, B. M., J. R. Stroud, M. J. McCORMICK, G. L. FAHNENSTIEL, M. L.
Stein, L. J. Welty, and G. A. LESHKEVICH. An event-driven phytoplankton
bloom in southern Lake Michigan observed by satellite. Geophysical
Research Letters 29(8):18-1 to 18-4 (2002).
Sea-viewing Wide field-of-view Sensor (SeaWiFS) images from June 1998
show a surprising early summer phytoplankton bloom in southern lake
Michigan that accounted for approximately 25% of the lake's annual gross
offshore algal primary production. By combining the satellite imagery
with in situ measurements of water temperature and wind velocity, we
show that the bloom was triggered by a brief wind event that was sufficient
to cause substantial vertical mixing even though the lake was already
stratified. We conclude that episodic events can have significant effects
on the biological state of large lakes and should be included in biogeochemical
process models.
LIU, P. C., and N. HAWLEY. Wave grouping characteristics in nearshore
Great Lakes II. Ocean Engineering 29:1415-1425 (2002).
This is a sequel with extensive new data to Liu's (Liu, 2000a. Wave
grouping characteristics in nearshore Great Lakes. Ocean Engineering
27, 1221-1230) exploratory study on wave grouping characteristics in
the nearshore Great Lakes. We analyze recent GLERL time-series measurements
recorded by pressure sensors deployed at four nearshore stations in
southern Lake Michigan during 1998-1999. With the advantage of continued
application of time-frequency wavelet spectrum analysis, the extensive
new measurements substantially confirmed the effectiveness of the empirical
characterization of wave grouping parameters defined in Liu. We show
that a wave group is really the basic element for a detailed understanding
of wave processes, in contrast to the conventional approach of using
a frequency spectrum as the basic element, which depends on the recording
length and requires the data to be stationary. While studying wave time-series
alone does not really alleviate the vast intricacies of the wind wave
processes, the embodiment of wave grouping as the predominant feature
in the wind wave processes clearly represents a significant step forward
toward sound conceptual advancement.
LIU, P. C., and N. Mori. Characterizing freak waves with wavelet transform
analysis. Proceedings, Rogue Waves 2000, M. Alagnon, and G. A. Athanassoulis
Eds., Brest, France, November 29-30, 2000. Ifremer, Brest, France, pp.
151-156 (2000).
This paper presents an analysis of a set of available freak wave measurements
gathered from several periods of continuous wave recordings made in
the Sea of Japan during 1986-1990 by the Ship Research Institute of
Japan. The analysis provides an ideal opportunity to catch a glimpse
of the incidence of freak waves. The results show that a well-defined
freak wave can be readily identified from the wavelet spectrum where
strong energy density in the spectrum is instantly surged and seemingly
carried over to the high frequency components at the instant the freak
wave occurs. Thus for a given freak wave, there appers a clear corresponding
signature shown in the time-frequency wavelet spectrum. Since freak
waves are primarily transient events occurring unexpectedly, wave transform
analysis on continuous, long duration wave measurements clearly represents
the most ideal approach to discern the localized characteristics of
freak waves for further exploration.
LOFGREN, B. M. Global warming influences on water levels, ice, and chemical
and biological cycles in lakes: some examples. American Fisheries Society
Symposium 32:15-22 (2002).
Climate change and variability significantly affect freshwater bodies
in ways that include effects on the water temperature profiles, total
water volumes, inflows and outflows, ice cover, primary productivity
and activity at higher trophic levels, and cycling of nutrients and
other chemical constituents. Understanding of this large array of potential
impacts involves many scientific disciplines, and cases can differ markedly
depending on the characteristics of the water bodies, including area,
depth, latitude, annual cycle of thermal stratification, nutrient and
toxic input, components of the ecosystem, and many other factors. This
paper gives brief summaries of several studies that focused on particular
examples of these effects, as presented during a special session titled
Potential Impacts of Climate Change on Large Lakes, at the meeting of
Societas Internationalis Limnologiae (SIL) in Melbourne, Australia on
6 February 2001. These studies include a general overview of the geological
and climatological factors that interacted to form the large lakes of
China, a study on water quantity and lake levels of the Laurentian Great
Lakes, a group of studies regarding effects on the heat content, thermal
structure, and ice cover of various lakes, and three studies of nutrient
cycling and biological activity in several lakes of northern Europe,
using the quasi-periodic North Atlantic Oscillation as a proxy for anthropogenic
greenhouse warming. This paper presents the main conclusions of each
of these studies; additional details can be obtained from the papers
cited here or directly from their authors.
Lotufo, G. R., and P. F. LANDRUM. The influence of sediment and feeding
on the elimination of polycyclic aromatic hydrocarbons in the freshwater
amphipod, Diporeia spp. Aquatic Toxicology 58:137-149 (2002).
http://www.glerl.noaa.gov/pubs/fulltext/2002/20020001.pdf
The elimination of non-polar organic contaminants from sediment dwelling
aquatic invertebrates was thought to be dominated by fecal elimination.
This was particularly thought to be the case for the amphipod, Diporeia
spp. that encapsulates the fecal material in a peritrophic membrane.
The elimination of selected PAH congeners by Diporeia spp. was
determined in the presence of three solid substrates and under water
only conditions. The elimination was generally enhanced by the presence
of a solid substrate whether or not the organism employed the material
as a food source. The greater the sorptive capacity of the substrate,
the greater its influence on the elimination process. Elimination via
the fecal route was generally insignificant except for the elimination
of BaP in the presence of sediment. In this case, the fecal elimination
accounted for up to 40% of the total elimination, and the extent of
elimination via the fecal route increased with the amount of fecal material
produced. Thus, it is clear from the above effort that the main mechanism
for elimination of contaminants in the presence of a substrate is primarily
via passive diffusion from the organism with subsequent sorption to
the solid substrate, which maintains the chemical activity gradient
between the organism and the water. This effort refutes the earlier
hypothesis that fecal elimination is the dominant route of elimination
for Diporeia spp., and that the peritrophic membrane plays any
substantial role in the elimination process.
Madenjian, C. P., G. L. FAHNENSTIEL, T. H. JOHENGEN, T. F. NALEPA, H.
A. VANDERPLOEG, G. W. Fleischer, P. J. Schneeberger, D. M. Benjamin, E.
B. Smith, J. R. Bence, E. S. Rutherford, D. S. Lavis, D. M. Robertson,
D. J. Jude, and M. P. Ebener. Dynamics of the Lake Michigan Food Web,
1970-2000. Canadian Journal of Fisheries and Aquatic Sciences 59:736-753
(2002). http://www.glerl.noaa.gov/pubs/fulltext/2002/20020015.pdf
Herein, we document changes in the Lake Michigan food web between 1970
and 2000 and identify the factors responsible for these changes. Control
of sea lamprey (Petromyzon marinus) and alewife (Alosa pseudoharengus)
populations in Lake Michigan, beginning in the 1950s and 1960s, had
profound effects on the food web. Recoveries of Lake Whitefish (Coregonus
ciupeaformis) and burbot (Lota iota) populations, as well
as the buildup of salmonine populations, were attributable, at least
in part, to sea lamprey control. Based on our analyses, predation by
salmonines was primarily responsible for the reduction in alewife abundance
during the 1970s and early 1980s. In turn, the decrease in alewife abundance
likely contributed to recoveries of deepwater sculpin (Myoxocephaius
thompsoni), yellow perch (Perca flavescens), and burbot populations
during the 1970s and 1980s. Decrease in the abundance of all three dominant
benthic macroinvertebrate groups, including Diporeia, oligochaetes,
and sphaeriids, during the 1980s in nearshore waters (50 m deep) of
Lake Michigan, was attributable to a decrease in primary production
linked to a decline in phosphorus loadings. Continued decrease in Diporeia
abundance during the 1990s was associated with the zebra mussel (Dreissena
polymorpha) invasion, but specific mechanisms for zebra mussels
affecting Diporeia abundance remain unidentified.
Millie, D. F., G. L. FAHNENSTIEL, H. J. Carrick, S. E. Lohrenz, and O.
M. E. Schofield. Phytoplankton pigments in coastal Lake Michigan: Distributions
during the spring isothermal period and relation with episodic sediment
resuspension. Journal of Phycology 38:639-648 (2002).
Phytoplankton pigment distributions during the spring isothermal periods
of 1998 and 1999 and their association with episodic sediment resuspension
were characterized in coastal waters of southern Lake Michigan. Total
and phylogenetic group chl a concentrations (derived using chemical
taxonomy matrix factorization of diagnostic carotenoids) corresponded
with assemblage and group biovolumes estimated from microscopic enumeration
(P <= 0.001). Diatoms and cryptophytes dominated assemblages and together
typically comprised greater than 85% of relative chl a. Total chl a
concentrations and both fucoxanthin x chl a and alloxanthin chl a ratios
were similar across depths (P > 0.05), indicating uniform distributions
of and photophysiological states for assemblages and diatoms and cryptophytes,
respectively, throughout the mixed water column. Total chl a concentrations
were not always spatially uniform from nearshore to offshore waters,
with the greatest variability reflecting the influence of tributary
inflows upon coastal assemblages. Sediment resuspension strongly influenced
water column particle density and light climate; however, total and
group chl a concentrations did not correspond with coefficients of K
and suspended particulate matter concentrations (P> 0.05). The correspondence
of both light attenuation and suspended particulate matter concentration
with relative diatom chl a (P <= 0.001) indicated an apparent association
between sediment resuspension and diatoms. This, and the negative association
(P<= 0.0001) between relative diatom and cryptophye chl a, corresponded
with the spatial dominance of diatom and cryptophyte chl a in nearshore
and offshore waters, respectively. The presence of viable chl a and
fucoxanthin within the surficial sediment layer, established this layer
as a potential source of meroplanktonic diatoms for nearshore assemblages.
Mori, N., P. C. LIU, and T. Yasuda. Analysis of freak wave measurements
in the Sea of Japan. Ocean Engineering 29:1399-1414 (2002).
This paper presents an analysis of a set of available freak wave measurements
gathered from several periods of continuous wave recordings made in
the Sea of Japan during 1986-1990 by the Ship Research Institute of
Japan. The analysis provides an ideal opportunity to catch a glimpse
of the statistics of freak waves in the ocean. The results show that
a well-defined freak wave may occur in the developed wind-wave condition:
S(f) f-4, with single-peak directional spectra. The crest and trough
amplitude distributions of the observed sea waves including freak waves
are different from the Rayleigh distribution, although the wave height
distribution tends to agree with the Rayleigh distribution. Freak waves
can be readily identified from the wavelet spectrum where a strong energy
density occurs in the spectrum, and is instantly surged and seemingly
carried over to the high-frequency components at the instant the freak
wave occurs.
Mulsow, S., P. F. LANDRUM, and J. A. ROBBINS. Biological mixing responses
to sublethal concentrations of DDT in sediments by Heteromastus filiformis
(capitellidae) using a 137Cs marker layer technique. Marine Ecology
Progress Series 239:181-191 (2002). http://www.glerl.noaa.gov/pubs/fulltext/2002/20020010.pdf
Sediment mixing by benthic macroinvertebrates is an important process
affecting the fate of sediment-bound and dissolved contaminants in marine
environments. A non-invasive, state-of-the-art radiotracer technique
was used to study sediment mixing by Heteromastus filiformis
(Capitellidae), a common marine head-down deposit feeder, exposed to
several sub-lethal concentrations of DDT (0, 5, 10 and 20 pg g-1; control,
Treatments 1, 2 and 3). Several horizontal sub-millimeter layers of
137Cs-labeled clay were deposited approximately every 2 cm in each of
3 replicate sediment columns per treatment; 4 polychaetes were then
introduced to each column and the y activity of each column was measured
vertically using an automated scan detector. Nonlinear least-square
fits were applied to obtain parameterized values that were used to determine
the mixing rates of each 137Cs layer over time. A simple diffusion model
was used to calculate biological diffusion coefficients (Db) for H.
filiformis. Overall mixing rates increased towards the surface.
Control and Treatment 1 had higher Db values at the surface compared
to Treatments 2 and 3. The Db depth profiles were similar in the control
and Treatments 1 and 2, with mixing occurring at the sediment water
interface and a subsurface maximum at 10 to 12 cm below this interface.
This pattern was not clear in Treatment 3, where Db had the lowest values
and decreased with depth. Bioturbation besides mixing of solids also
changed the water content throughout the sediment column. Porosity profiles
at the end of the experiments increased by 10 to 20% at 10 to 12 cm
depths compared to above and below this horizon. The DDT depth concentration
profiles decreased towards the surface as a result of the mixing by
the benthic macroinvertebrates, clearly indicating removal/uptake by
the organism. The feeding rate constant (gb, % h-1) in the control showed
a maximum at 7 to 12 cm. However, the gb in the treatments was essentially
constant with depth. For all treatments and the control, the burial
rate (Wb) (downward movement of radiolabeled layers) decreased with
depth. The surface layers were buried faster (ANOVA, p < 0.05) in the
control than in sediments containing DDT. A sensitivity analysis comparing
burial rate, Db, gb (surface only) and worm weights showed that worm
weights and burial rate have the highest fractional rate changes per
pg g-1 DDT.
MUZZI, R. W., and B. J. EADIE. The design and performance of a sequencing
sediment trap for lake research. Marine Technology Society Journal
36(2):23-28 (2002). http://www.glerl.noaa.gov/pubs/fulltext/2002/20020023.pdf
Static sediment traps have been successfully used to examine the processes
of particle flux and resuspension in large lakes and coastal systems.
Although the traps themselves are inexpensive, the deployment and retrieval
of them is costly, which restricts both the quantity andfequency of
samples. To overcome this, a programmable sequencing sediment trap was
designed and tested for use in large lakes and coastal systems. Sediment
is collected into a carousel of 23 standard 60 ml (Nalgene) polyethylene
sample bottles. The sequencing design incorporates an electric motor
and paddle to rotate the carousel so that one sample bottle at a time
is exposed according to a preprogrammed schedule. These traps incorporate
a cylindrical design with a 20 cm collection opening and an 8:1 aspect
ratio. The in icro-controller monitors the operation and records operational
parameters allowing confirmation of the exposure time of each bottle.
Several field tests were conducted to verify' the precision and uniformity
of the sediment collection. Improvements made over the 10 years of deployment
experience and field testing have resulted in a very reliable and low-cost
instrument.
NALEPA, T. F., D. L. FANSLOW, M. B. LANSING, G. A. LANG, M. FORD, G.
GOSTENIK, and D. J. HARTSON. Abundance, biomass, and species composition
of benthic macroinvertebrate populations in Saginaw Bay, Lake Huron, 1987-96.
NOAA Technical Memorandum GLERL-122, Great Lakes Environmental Research
Laboratory, Ann Arbor, MI, 32 pp. (2002). ftp://ftp.glerl.noaa.gov/publications/tech_reports/glerl-122
This technical report gives the basic results of benthic macroinvertebrate
surveys conducted in Saginaw Bay between 1987 and 1996. Yearly surveys
were conducted over this time period to assess trends in macroinvertebrate
density, biomass, and species composition. When the surveys were initiated
in 1987-88, the main objective was to assess the response of the benthic
community to phosphorus abatement programs that were implemented in
the mid-1970s. Improvements in water quality were reported after these
programs (Bierman et al. 1984), and a two-year sampling program in 1987-88
was designed to determine if similar improvements were evident in the
macroinvertebrate community. When the zebra mussel (Dreissena polymorpha)
became established in the Great Lakes in 1988 (Hebert et al. 1989),
sampling was resumed in 1990 and continued through 1996 with the objective
of assessing impacts of Dreissena. Dreissena colonized
the bay in 1991 (Nalepa et al. 1995). Thus, the data collected during
the time of this study can be divided into two distinct periods: post-phosphorus
abatement/pre-Dreissena (1987-90) and post-Dreissena (1991-96).
Data are presented in this report with little attempt at interpretation;
detailed analysis and discussions of relevance will be provided in other
publications. Rather, the purpose of this report is to provide the raw
data and basic details of the sampling program, including station locations
and characteristics, sampling methods, and laboratory procedures. In
addition, results of a comparative study of two samplers, the Peterson
and Ponar grabs, is presented. The former grab was used in benthic surveys
conducted in the bay in the 1950s and 1960s, while the latter grab has
been used since the early 1970s. The relative efficiency of these two
grabs was examined to more accurately depict density trends from the
1950s to the present.
NALEPA, T. F., D. J. HARTSON, D. L. FANSLOW, and G. A. LANG. Recent population
changes in freshwater mussels (Bivalvia: Unionidae) and zebra mussels
(Dreissena polymorpha) in Lake St. Clair, USA. American Malacological
Bulletin 16(1/2):141-145 (2001).
To determine trends in abundances, we conducted a survey of freshwater
mussels (Bivalvia: Unionidae) and zebra mussels (Dreissena polymorpha)
[Pallas, 1771] at five sites in the northwestern portion of lake St.
Clair in 1997. Previous, more extensive spatial surveys between 1986
and 1994 showed that unionids were mostly eliminated from the lake as
a result of zebra mussel infestation, but at least a few unionids were
still present in the northwestern portion in 1994. The 1994 survey also
showed that zebra mussel densities were still increasing in this portion
of the lake. In the present survey, no live unioninds were collected
despite a sampling effort modified from prior surveys specifially to
locate live individuals. From these results, we believe that freshwater
mussels have been eliminated from the open waters of Lake St. Clair.
Zebra mussel populations appear to have reached a steady state in the
northwest portion as evidenced by a decrease in mean density from 2,246
m-2 in 1994 to 1,237 m-2 in 1997, and a decrease in the mean size of
individuals in the population. Although they were common in previous
surveys, we did not collect any zebra mussels with a shell length >20
mm.
Norcross, B. L., E. D. Brown, R. J. Foy, M. Frandsen, S. M. Gay, T. C.
Kline, D. M. MASON, E. V. Patrick, A. J. Paul, and K. D. E. Stokesbury.
A synthesis of the life history and ecology of juvenile pacific herring
in Prince William Sound, Alaska. Fisheries Oceanography 10(1):42-57
(2001).
Physical and biological variables affecting juvenile Pacific herring
(Clupea pollosi) in Prince William Sound (PWS) from 1995 to 1998
were investigated as part of a multifaceted study of recruitment, the
Sound Ecosystem Assessment (SEA) program. Though more herring larvae
were retained in eastern PWS bays, ages-0 and -1 herring used bays throughout
PWS as nursery areas. Water transported into PWS from the Gulf of Alaska
(GOA) contributed oceanic prey species to neritic habitats. Consequently,
variations in local food availability resulted in different diets and
growth rates of herring among bays. Summer food availability and possible
interspecific competition for food in nursery areas affected the autumn
nutritional status and juvenile whole body energy content (WBEC), which
differ among bays. The WBEC of age-0 herring in autumn was related to
over-winter survival. The limited amount of food consumption in winter
was not sufficient to meet metabolic needs. The smallest age-0 fish
were most at risk of starvation in winter. Autumn WBEC of herring and
winter water temperature were used to model over-winter mortality of
age-0 herring. Differences in feeding and energetics among nursery areas
indicated that habitat quality and age-0 survival were varied among
areas and years. These conditions were measured by temperature, zooplankton
abundance, size of juvenile herring, diet energy, energy source (GOA
vs. neritic zooplankton), WBEC, and within-bay competition.
POTHOVEN, S. A., G. L. FAHNENSTIEL, and H. A. VANDERPLOEG. Population
dynamics of Bythotrephes cederstroemii in southeast Lake Michigan
1995-1998. Freshwater Biology 46:1491-1501 (2001).
1. Population characteristics (density, size, reproductive patterns)
of the predatory cladoceran Bythotrephes cederstroemii in south-east
Lake Michigan were monitored at an offshore station (110 m) in 1995-98
and at a nearshore station (45 m) in 1997-98. 2. The mean density of
B. cederstroemii at the offshore station was generally highest
in July-September (145-914 m-2) and at the nearshore station in October-November
(168-1625 m-2). In 1995 and 1998, density was also high at the offshore
station in November (211-284 m-2). Fish predation may limit B. cederstroemii
in nearshore regions in the summer. The maximum annual densities of
B. cederstroemii for 1995-98 were generally similar to those
reported from the late 1980s, when the species arrived in Lake Michigan.
3. Body size increased rapidly each year to a maximum in August. Thereafter,
body size declined and converged for Stage-2 and 3 individuals, suggesting
food scarcity or size-selective fish predation was affecting large individuals.
4. Most reproduction occurred asexually (90%), and by stage 2 or 3 females
(99%). Asexual brood size was highest when B. cederstroemii first
appeared each year, and decreased in August, when larger neonates were
produced. There appeared to be differences in reproductive mode for
stage 2 and 3 females, with a higher percentage of stage 2 females reproducing
sexually.
POTHOVEN, S. A., T. F. NALEPA, P. J. Schneeberger, and S. B. BRANDT.
Changes in diet and body condition of Lake Whitefish in southern Lake
Michigan associated with changes in benthos. North American Journal
of Fisheries Management 21:876-883 (2001).
We evaluated the long-term trends of the benthic macroinvertebrate
community (1980-1999) and biological attributes of lake whitefish Coregonus
clupeaformis (1985-1999) in southeastern Lake Michigan; We also
determined what food types were important to lake whitefish in an area
where the amphipod Diporeia had not yet declined in 1998 and
how the diet of lake whitefish changed as Diporeia declined during
1999-2000. Zebra mussels Dreissena polymorpha invaded the study
area in 1992; Diporeia began to decline in 1993 and was nearly
absent by 1999. The body condition of lake whitefish decreased after
1993 and remained low thereafter The length at age and weight at age
of lake whitefish was lower in 1992-1999 than in 1985-1991- After declines
of Diporeia off the city of Muskegon, Michigan, between 1998
and 1999-2000, the proportion of Diporeia in the diet by weight
fell from 70% to 25% and the percent occurrence decreased from 81% to
45%. In contrast, the proportion of lake whitefish that ate other prey,
such as Mysis relicta (an opossum shrimp), ostracods. oligochaetes,
and zooplankton, increased in the same period; At sites south of Muskegon,
where the density at Diporeia has been low since 1998, chironomids,
zebra mussels, and fingernail clams (Shaeriidae family) were the most
important diet items of lake whitefish. Decreases in body condition
and growth are associated with the loss of the high-energy prey resource
Diporeia, the consumption of prey with lower energy content,
such as zebra mussels, and possible density-dependence. Commercial harvests
of lake whitefish will probably decrease because of low body condition
and growth. Future management may require changes in harvest quotas,
size restrictions, and depth restrictions as zebra mussel-related impacts
spread northward in Lake Michigan.
QUIGLEY, M. A., P. F. LANDRUM, W. S. GARDNER, C. R. STUBBLEFIELD, and
W. M. GORDON. Respiration, nitrogen excretion, and O:N ratios of the Great
Lakes amphipod, Diporeia sp. NOAA Technical Memorandum GLERL-120,
NOAA, Great Lakes Environmental Research Laboratory, Ann Arbor, MI, 16
pp. (2002). ftp://ftp.glerl.noaa.gov/publications/tech_reports/glerl-120
Diporeia sp. (formerly Pontoporeia hoyi) Amphipoda, Crustacea
obtained from a 24-29 m deep site in southeastern Lake Michigan were
held in stoppered 60 mL BOD bottles in darkness and at 4oC during 24-hour
intervals. Change in dissolved oxygen concentration of filtered lakewater
within test vessels indicated that mean Diporeia sp. oxygen consumption
ranged from 13.9 to 33.9 mg O2 g-1 DW d-1. Test vessel acclimation studies
revealed a minor increase in oxygen uptake early in the incubation interval
that that was not reflected in overall oxygen consumption measured over
the entire 24-hour period. Mean oxygen consumption of amphipods provided
with a coarse, ignited sand substrate was not significantly different
(P<0.05) from O 2 consumption of animals in test vessels where no substrate
was provided. In a series of 10 other experiments, where initial ambient
oxygen concentration was varied (from 95 to 23% saturation), Michaelis-Menten
kinetics analysis indicated that Diporeia sp. was able to maintain
a relatively uniform level of oxygen consumption over the upper portion
of oxygen concentrations tested. Vmax (predicted O2 consumption at 100%
saturation) was 25.5 mg O2 g-1DW d-1 and fell within the 13.9-33.9 mg
O2 g-1DW d-1 range noted in 24-hour oxygen consumption experiments at
near-saturation O2 levels. Km (the predicted O2 concentration where
oxygen consumption had declined to 50% of the Vmax value) was 2.2 mg
L-1. Diporeia sp. nitrogen (ammonia) excretion, simultaneously
measured during three of the oxygen consumption experiments, ranged
from 0.45 to 0.77 ng-atom N mg -1 DW h-1. Calculation of O:N ratios
(atoms of oxygen consumed per atom of N excreted) implied that substrates
catabolized by Diporeia sp. consisted primarily of lipids since
most (62%) O:N values were greater than 60. These results complement
previously observed high lipid content of Diporeia sp. and further
suggest that the economy of lipids is a prominent aspect of the amphipod¹s
life history.
QUINN, F. H. Secular changes in Great Lakes water level changes. Journal
of Great Lakes Research 28(3):451-465 (2002).
The three primary scales of Great Lakes water level fluctuations are
interannual, seasonal, and episodic. Of, these three, the seasonal water
level fluctuations have received relatively little attention. The Great
Lakes water levels have a well defined seasonal cycle driven primarily
by snowmelt in the spring and summer and lake evaporation in the fall
and winter. The present average seasonal cycle ranges from 26 cm on
Lake Superior to 38 cm on Lake Ontario. Great Lakes monthly water levels
from 1860 to 2000 were used to assess changes in the seasonal cycle
of each of the Great Lakes and Lake St. Clair over the past 140 years.
Changes are found on all of the lakes during the period of record. They
usually resulted in a decrease in seasonal range and a time shift in
the months of seasonal maximum and minimum. The effects of lake regulation
were found to be negligible in the case of Lake Superior and significant
for Lake Ontario. The major changes on Lakes St. Clair and Erie are
likely a result of changes in the connecting channels ice retardation
rather than changes in seasonal hydrometeorology. Seasonal cycle regimes
are delineated for each of the lakes and possible rationale for the
changes discussed.
QUINN, F. H., R. A. ASSEL, and C. E. SELLINGER. Hydro-climatic factors
and socioeconomic impacts of the recent record drop in Laurentian Great
Lakes water levels. Preprints of the 13th Symposium on Global Change and
Climate Variations, Orlando, Florida, January 13-17, 2002. American Meteorological
Society, Boston, MA, pp. 91-93 (2002).
The Laurentian Great Lakes, comprise the United States premier surface
water resource with a basin area of 770.000 km2. This water resource
is shared between the U.S. and Canada and supports many important uses
including recreational boating, commercial navigation, sports fishing,
hydroelectric power, industry, municipal water supply, recreation, and
fish and wildlife habitat. The Great Lakes system, Figure 1, which includes
the five Great Lakes, Superior, Michigan, Huron, Erie. and Ontario,
and Lake St. Clair and the connecting channels is naturally well regulated
due to the large lake surface areas and constricted outlet channels.
Two of the lakes, Superior and Ontario, are regulated. This has resulted
in the lakes fluctuating through a relatively small range in levels,
about 1.8 m. Because of the small range in water levels, industrial
and recreational uses are sensitive to even small changes in lake levels.
The lakes had been in an extremely high levels regime from the late
1960s through the late 1990s with record highs being set in 1973 and
1986. However, beginning with the 1997-1998 El Nino, the lakes began
a dramatic decline in water levels that was notable for both the magnitude
and the rapidity of the drop. Currently Lake Michigan-Huron is the lowest
since 1965, while this spring Lake Superior was the lowest since 1925.
In this study we compare the drop in levels with similar past events,
examine the hydroclimatological factors leading to the decline in levels
and look at both positive and negative impacts. We will concentrate
on Lakes Michigan and Huron, one lake hydraulically, which have had
the largest impacts.
REID, D. F., and M. I. Orlova. Geological and evolutionary underpinnings
for the success of ponto-caspian species invasions in the Baltic Sea and
North American Great Lakes. Canadian Journal of Fisheries and Aquatic
Sciences 59:1144-1158 (2002). http://www.glerl.noaa.gov/pubs/fulltext/2002/20020011.pdf
Between 1985 and 2000, ~70% of new species that invaded the North American
Great Lakes were endemic to the Ponto-Caspian (Caspian, Azov, and Black
seas) basins of eastern Europe. Sixteen Ponto-Caspian species were also
established in the Baltic Sea as of 2000. Many Ponto-Caspian endemic
species are characterized by wide environmental tolerances and high
phenotypic variability. Ponto-Caspian fauna evolved over millions of
years in a series of large lakes and seas with widely varying salinities
and water levels and alternating periods of isolation and open connections
between the Caspian Sea and Black Sea depressions and between these
basins and the Mediterranean Basin and the World Ocean. These conditions
probably resulted in selection of Ponto-Caspian endemic species for
the broad environmental tolerances and euiyhalinity many exhibit. Both
the Baltic Sea and the Great Lakes are geologically young and present
much lower levels of endemism. The high tolerance of Ponto-Caspian fauna
to varying environmental conditions, their ability to survive exposure
to a range of salinities, and the similarity in environmental conditions
available in the Baltic Sea and Great Lakes probably contribute to the
invasion success of these species. Human activities have dramatically
increased the opportunities for transport and introduction and have
played a catalytic role.
RODIONOV, S., R. A. ASSEL, and L. R. HERCHE. Tree-structured modeling
of the relationship between Great Lakes ice cover and atmospheric circulation
patterns. Journal of Great Lakes Research 27(4):486-502 (2001).
Seasonal maximum ice concentration (percentage of lake surface covered
by ice) for the entire Laurentian Great Lakes and for each Great Lake
separately is modeled using atmospheric teleconnection indices. Two
methods, Linear Regression (LR) and Classification and Regression Trees
(CART), are used to develop empirical models of the interannual variations
of maximum ice cover. Thirty-four winter seasons between 1963 and 1998
and nine teleconnection indices were used in the analysis. The ice cover
characteristics were different for each Great Lake. The ice cover data
lent itself better to CART analysis, because CART does not require a
priori assumptions about data distributions characteristics to perform
well. The stepwise LR models needed more variables, and in general,
did not explain as much of the variance as the CART models. Two variables,
the Multivariate ENSO index and Tropical/Northern Hemisphere index,
explained much of the interannual variations in ice cover in the CART
models. Composite atmospheric circulation patterns for threshold values
of these two indices were found to be associated with above-and below-normal
ice cover in the Great Lakes. Thus, CART also provided insight into
physical mechanisms (atmospheric circulation characteristics) underlying
the statistical relationships identified in the models.
RUBERG, S. A., H. A. VANDERPLOEG, J. F. CAVALETTO, G. A. LANG, J. R.
LIEBIG, T. C. MILLER, and M. AGY. Plankton survey system. Proceedings
of the Oceans 2001 MTS/IEEE Conference, Honolulu, HI, November 5-8, 2001.
Marine Technology Society, Washington, DC, pp. 1899-1903 (2001).
The Plankton Survey System (PSS), developed at the National Oceanic
and Atmospheric Administration's (NOAA) Great Lakes Environmental Research
Laboratory (GLERL), has been designed to collect high temporal and spatial
resolution marine environmental data in three dimensions. The system
has proven effective in providing valuable survey information before,
during and after sediment re-suspension events in Lake Michigan in support
of GLERL's NOAA/NSF funded Episodic Events Great Lakes Experiment (EEGLE)
program. The PSS is a towed multi-sensor platform capable of measuring
turbidity, chlorophyll a, photosynthetically active radiation (PAR),
conductivity, temperature, and zooplankton spatial distributions. All
sensors are integrated using a serial data interface. All data are geo-referenced
and registered with time, depth, and vehicle pitch, roll, and speed
information. A deck unit supplies power for the underwater vehicle components
and provides interfaces for data collection and system monitoring. System
software provides real-time display of all marine environmental measurements
and vehicle status. Zooplankton spatial and individual size distributions
are measured using an optical plankton counter (OPC). The OPC measures
particle size distributions (0.25 -14mm) using an LED array and a photodiode
receiver. Deflections caused by particles crossing the LED generated
light beam (4x20x100 mm) are detected by the receiver and digitized.
Present work is focused on moving the OPC beyond use as merely a survey
tool to calibrating the instrument using laboratory and field measurements.
Laboratory calibration plans include the use of specified particles
to establish a reference and subsequent investigations using live zooplankton
samples. A range of issues involving the implications of variations
in zooplankton body characteristics on OPC detection threshold, turbidity
on OPC signal-to-noise ratio, tow vehicle orientation and vehicle and
OPC channel turbulence will also be investigated.
Schloesser, D. W., and T. F. NALEPA. Comparison of 5 benthic samplers
to collect burrowing mayfly nymphs (Hexagenia spp: Ephemeroptera:Ephemeridae)
in sediments of the Laurentian Great Lakes. Journal of the North American
Benthological Society 21(3):487-501 (2002).
The recent return of burrowing mayfly nymphs (Hexagenia spp.)
to western Lake Erie of the Laurentian Great Lakes has prompted a need
to find a sampler to obtain the most accurate (i.e., highest mean density)
and precise (i.e., lowest mean variance) abundance estimates of nymphs.
The abundance of burrowing nymphs is important because it is being used
as a measure of ecosystem health to determine management goals for fisheries
and pollution abatement programs for waters in both North America and
Europe. We compared efficiencies of 5 benthic grab samplers (Ponar,
Ekman, petite Ponar, Petersen, and orange-peel) to collect nymphs from
sediments of western Lake Erie and Lake St. Clair. Samplers were used
at one site with soft substrates in both lakes in 1997 (Ponar, Ekman,
petite Ponar, and Petersen) and 1998 (Ponar and Ekman), and at one site
with soft and one site with hard substrates in Lake St. Clair in 1999
(Ponar and orange-peel). In addition, the Ponar, Ekman, and Petersen
samplers were used at one site with soft substrates of western Lake
Erie in 2000 to examine the causes of differences among samplers. The
Ponar was more accurate than the other samplers; it collected the highest
densities of nymphs for 31 of 32 date and site comparisons. In soft
substrates, the order of decreasing overall densities was: Ponar>Petersen>petite
Ponar>Ekman in western Lake Erie and Ponar>Petersen> Ekman>petite Ponar
in Lake St. Clair in 1997, Ponar>Ekman in both lakes in 1998, and Ponar>orange-peel
in Lake St. Clair in 1999. In hard substrates, the Ponar was more accurate
than the orange-peel in Lake St. Clair in 1999. Precision of the Ponar
was generally greater than the Ekman, petite Ponar, and Petersen but
similar to the orange-peel. Higher densities of nymphs obtained with
the Ponar than other grabs are attributed to its relatively heavy weight,
which allows it to sample deeper in sediments than the Ekman and petite
Ponar. Also, the Ponar has a screened top, which allows it to minimize
hydraulic shock waves more than the Petersen, and uniform sides, which
allow it to sample nymphs more uniformly through sediments than the
orange-peel. We recommend that future estimates of burrowing mayfly
densities be obtained with a standard Ponar sampler similar to the one
used in our study because it will yield the most accurate and precise
measurements of burrowing mayfly nymphs such as Hexagenia spp.
Schneider, A. R., B. J. EADIE, and J. E. Baker. Episodic particle transport
events controlling PAH and PCB cycling in Grand Traverse Bay, Lake Michigan.
Environmental Science and Technology 36(6):1181-1190 (2002).
To evaluate the influence of episodic events on particle and hydrophobic
organic contaminant (HOC) cycling in the Great Lakes, we deployed sequencing
sediment traps at two locations in the western arm of Grand Traverse
Bay, Lake Michigan. The traps collected integrated samples of settling
particles every 2weeks from May 1997 to September 1999. The total polycyclic
aromatic hydrocarbon (t-PAH) and total polychlorinated biphenyl (t-PCB)
settling fluxes from the surface waters in the southern site were significantly
greater than those from the northern site. In addition, there were more
frequent brief increases in the mass flux to the southern site than
to the northern site. These episodic events, which occurred only 20%
of the time, accounted for 65% of both the mass flux and t-PAH flux.
The t-PCB flux was not influenced by these episodic events, and only
18% of the t-PCB flux occurred during these events. PAHs and PCBs appear
to be tracing different types of particles in the water column. Several
large mass flux events characteristic of seiches were observed simultaneously
in the benthic nepheloid layer (BNL) at both the northern and the southern
sites. The particles settling as a result of these resuspension events
had lower t-PCB and t-PAH concentrations than particles settling at
other times. This suggests that the material settling into the traps
on the high mass flux days is composed of a mixture of the less contaminated
underlying resuspended sediment and the "regular" contaminant-rich particles
settling into the BNL.
Soster, F. A., G. Matisoff, P. L. McCall, and J. A. ROBBINS. In situ
effects of organisms on porewater geochemistry in Great Lakes sediments.
In Organism-Sediment Interactions, J.Y. Aller, S. A. Woodin and
R. C. Aller Eds., University of South Carolina, Columbia, SC, pp. 279-294
(2001).
Soft-bottom habitats in the Great Lakes are numerically dominated by
deposit-feeding oligochaete annelids; tube-building filter-feeding chironomid
insect larvae, and deposit-feeding amphipods, this last group being
relatively abundant only in deeper oligotrophic bottoms. The abundance
of macrobenthos colonizing uninhabited sediment trays and residing in
natural bottom sediments at two sites in Lake Erie were compared with
geochemical profiles obtained from porewater peepers. Differences in
geochemical profiles were due more to differences in abundances of chironomid
larvae (Chironomus plumosus) than to differences in tubificid
oligochaete abundance. Porewater concentrations of soluble reactive
silicate (SRS), ammonium, carbonate alkalinity, and soluble reactive
phosphate (SRP) were lower in western Lake Erie tray sediments, where
C. plumosus were more abundant; than in natural bottom sediments
where C. plumosus were relatively rare. The opposite abundance
pattern was observed in the central basin, where C. plumosus
were more abundant in natural sediments and porewater concentrations
of SRS, ammonium, and ferrous iron were lower than in tray sediments
from the same site. In similar sediments from Lower Saginaw Bay, Lake
Huron, geochemical fluxes were determined from changes in concentrations
of water overlying sediment cores incubated shipboard at in situ temperatures.
There were significant correlations between ammonia flux, SRS flux,
and chironomid abundance, between SRP flux and mature tubificid abundance,
and between nitrate flux (into the sediment) and immature tubificids.
A faunal succession from a community with abundant Chironomus
larvae to one with abundant tubificid worms might cause a geochemical
succession. Early colonizing Chironomus larvae decrease porewater
concentrations of SRS, ammonium, and bicarbonate alkalinity and increase
the flux out of the sediment (and for ammonium, also may indirectly
increase the rate of nitrification). Concentrations of ferrous iron
and SRP are also depressed, but there is no enhanced flux because iron
is precipitated near burrow walls after contact with oxygen and adsorbs
phosphate, so iron and phosphate do not accumulate in the burrow pore
waters. Porewater concentrations of SRS, ammonium, bicarbonate alkalinity,
ferrous iron, and SRP are high in the presence of slower colonizing
tubificid worms, but the effect that worms have on the flux of most
of these species is more complicated.
Steevens, J. A., and P. F. LANDRUM. Development of a biological-effects-based
approach to assess the significance of contaminant bioaccumulation. ERDC/TN
EEDP-01-48, U.S. Army Engineer Research and Development Center, EEDP Technical
Notes Collection, 9 pp. (2002). http://www.glerl.noaa.gov/pubs/fulltext/2002/20020013.pdf
This technical note describes the development of an alternative approach
to evaluate chronic toxicity and the significance of contaminant bioaccumulation
in dredged material assessments. It describes potential approaches and
outlines the experimental progress of a project focusing on an effects-based
approach to assess bioaccumulation.
VANDERPLOEG, H. A., T. F. NALEPA, D. J. Jude, E. L. MILLS, K. T. HOLECK,
J. R. LIEBIG, I. A. Grigorovich, and H. Ojaveer. Dispersal and emerging
ecological impacts of Ponto-Caspian species in the Laurentian Great Lakes.
Canadian Journal of Fisheries and Aquatic Sciences 59:1209-1228
(2002). http://www.glerl.noaa.gov/pubs/fulltext/2002/20020012.pdf
We describe, explain, and "predict" dispersal and ecosystem impacts
of six Ponto-Caspian endemic species that recently invaded the Great
Lakes via ballast water. The zebra mussel, Dreissena polymorpha,
and quagga mussel, Dreissena bugensis, continue to colonize hard
and soft substrates of the Great Lakes and are changing ecosystem function
through mechanisms of ecosystem engineering (increased water clarity
and reef building), fouling native mussels, high particle filtration
rate with selective rejection of colonial cyanobacteria in pseudofeces,
alteration of nutrient ratios, and facilitation of the rapid spread
of their Ponto-Caspian associates, the benthic amphipod Echinogamarus
ischmus and the round goby, Neogobius melanostomus, which
feeds on zebra mussels. The tubenose goby, Protemrhinus marmoratus,
which does not feed on zebra mussels, has not spread rapidly. Impacts
of these benthic invaders vary with site: in some shallow areas, habitat
changes and the Dreissena -> round goby -> piscivore food chain
have improved conditions for certain native game fishes and waterfowl;
in offshore waters, Dreissena is competing for settling algae
with the native amphipod Diporeia spp., which are disappearing
to the detriment of the native deep-water fish community. The predatory
cladoceran Cerocopagis pengoi may compete with small fishes for
zooplanktonand increase food-chain length.
Willete, M. T., R. T. Cooney, V. Patrick, D. M. MASON, G. L. Thomas,
and D. Scheel. Ecological processes influencing mortality of juvenile
pink salmon (s) in Prince William Sound, Alaska. Fisheries Oceanography
10(1):14-41 (2001).
Our collaborative work focused on understanding the system of mechanisms
influencing the mortality of juvenile pink salmon (Oncorhynchns
gorbuscha) in Prince William Sound, Alaska. Coordinated field
studies, data analysis and numerical modelling projects were used
to identify and explain the mechanisms and their roles in juvenile
mortality. In particular, project studies addressed the identification
of major fish and bird predators consuming juvenile salmon and the
evaluation of three hypotheses linking these losses to (i) alternative
prey for predators (prey-switching hypothesis); (ii) salmon foraging
behaviour (refuge-dispersion hypothesis); and (iii) salmon size and
growth (size-refuge hypothesis). Two facultative planktivorous fishes.
Pacific herring (Clupea pallasi) and walleye pollock (Theragra
chalcogramma), probably consumed the most juvenile pink salmon
each year, although other gadids were also important- Our prey-switching
hypothesis was supported by data indicating that herring and pollock
switched to alternative nekton prey, including juvenile salmon, when
the biomass of large copepods declined below about 0-2 g m-3. Model
simulations were consistent with these findings, but simulations suggested
that a June pteropod bloom also sheltered juvenile salmon from predation.
Our refuge-dispersion hypothesis was supported by data indicating
a five-fold increase in predation losses of juvenile salmon when salmon
dispersed from nearshore habitats as the biomass of large copepods
declined. Our size-refuge hypothesis was supported by data indicating
that size- and growth-dependent vulnerabilities of salmon to predators
were a function of predator and prey sizes and the timing of predation
events. Our model simulations offered support for the efficacy of
representing ecological processes affecting juvenile fishes as systems
of coupled evolution equations representing both spatial distribution
and physiological status. Simulations wherein model dimensionality
was limited through construction of composite trophic groups reproduced
the dominant patterns in salmon survival data. In our study, these
composite trophic groups were six key zooplankton taxonomic groups,
two categories of adult pelagic fishes, and from six to 12 groups
for tagged hatchery-reared juvenile salmon. Model simulations also
suggested the importance of salmon density and predator size as important
factors modifying the predation process.
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