Source: CORNELL UNIVERSITY submitted to
EFFECTS OF WEAK ELECTRIC FIELDS ON AMPHIBIAN BEHAVIOR AND REPRODUCTION.
 
PROJECT DIRECTOR: Adler, K.
 
PERFORMING ORGANIZATION
NEUROBIOLOGY AND BEHAVIOR
CORNELL UNIVERSITY
ITHACA,NY 14853
 
NON TECHNICAL SUMMARY: Phylogenetic distribution of electroreception in salamanders that have aquatic larvae. This study will determine the phylogenetic distribution and functions of electroreception in salamanders. It will also investigate the disruptive effects of stray voltages in natural environments on salamander behavior and reproduction.
 
OBJECTIVES: Electroreception is an ancient sensory capability in anamniotic aquatic vertebrates, but has been lost, independently, in most bony fishes, frogs, and amniotes (reptiles, birds, and mammals). Recently, it has been reported that European salamanders in two families are sensitive to sine-wave currents and to DC pulses with thresholds in the range of 0.1 to 2mV/cm. No function has been ascribed to this response. Of the eight generally recognized families of salamanders, five are native to New York and two others to Florida, including the Sirenidae which is the sister-group to all other living salamanders. We propose to determine the phylogenetic distribution of electroreceiption in salamanders, including terrestrial species that have aquatic larvae and aquatic species whose ancestors were terrestrial. Furthermore, we will determine the normal function of electroreception--presumably the discovery of prey by detection of their electromyograms--and we will investigate the disruptive effects of stray voltages in natural environments on salamander behavior and reproduction.
 
APPROACH: Experiments on the function of electroreception will be conducted in all glass aquaria and plastic pools, using chloridized silver ball electrodes dipped into deionized water which can produce a wide variety of electrical sine-wave currents and pulses of different polarity and duration, clicks, and noise bursts. Electrical signals will be associated with food rewards in conditioning trials. In other tests, electrical stimuli will simulate those of natural prey items; salamanders should search for prey when signaling electrodes are hidden or display other overt behavior. Preliminary tests show that these methods are feasible. In studies on reproduction, the effects of different electrical signals on courtship behavior, egg laying, and hatching success will be determined. Finally, the influence of extraneous AC fields on prey capture and reproduction will be observed. Only noninvasive techniques will be used.
 
CRIS NUMBER: 0182631 SUBFILE: CRIS
PROJECT NUMBER: NYC-191401 SPONSOR AGENCY: CSREES
PROJECT TYPE: HATCH PROJECT STATUS: TERMINATED MULTI-STATE PROJECT NUMBER: (N/A)
START DATE: Oct 1, 1999 TERMINATION DATE: Sep 30, 2004

GRANT PROGRAM: (N/A)
GRANT PROGRAM AREA: (N/A)

CLASSIFICATION
Knowledge Area (KA)Subject (S)Science (F)Objective (G)Percent
305399930902.280%
301399910602.220%

CLASSIFICATION HEADINGS
KA305 - Animal Physiological Processes
KA301 - Reproductive Performance of Animals
S3999 - Animal research, general
F1060 - Biology (whole systems)
F3090 - Sensory science (human senses)
G2.2 - Increase Efficiency of Production and Marketing Systems


RESEARCH EFFORT CATEGORIES
BASIC 60%
APPLIED 40%
DEVELOPMENTAL (N/A)%

KEYWORDS: reproductive performance; amphibia; salamanders; sensory receptors; animal physiology; sensitivity; phylogenetics; electromyography; environmental impact; electric current; electrical properties; signals; egg laying; hatching; courtship; animal behavior; predation

PROGRESS: Oct 1, 1999 TO Sep 30, 2004
Electroreception is an ancient sensory capability in anamniotic aquatic vertebrates, but it has been lost, independently, in most bony fishes, frogs, and amniotes (reptiles, birds, mammals). The purpose of this research program was to determine the phylogenetic pattern of electroreception among the ten extant families of salamanders, including terrestrial species that have aquatic larvae (several families) and aquatic species whose ancestors were terrestrial (Amphiumidae). Furthermore, we wished to determine the normal functions of electroreception in salamanders and to investigate the disruptive effects of stray voltages in natural environments on salamander behavior and reproduction. Experiments were conducted in all-glass aquaria, using chloridized silver ball electrodes in deionized water; this apparatus allowed us to produce a wide variety of electrical sine-wave currents and DC pulses of different polarity and duration, clicks, and noise bursts. Electrical signals were associated with food rewards in conditioning trials. Only non-invasive techniques were used. All animals were freshly collected from the field, trained, and then tested. These tests show that one or more life stages of representative species of several salamander families are sensitive to sine-wave currents and to DC pulses with thresholds in the range of 0.05 to 3mV/cm. The distribution of this sensitivity (+ presence; - absence) was determined to be as follows: Family Proteidae--Necturus maculosus: aquatic larvae (not available for testing); aquatic adults (+). Family Ambystomatidae--Ambystoma maculatum: aquatic larvae (+); terrestrial adults (-). Family Salamandridae--Notophthalmus viridescens: aquatic larvae (+); terrestrial eft (-); aquatic adult (+). Family Plethodontidae--Gyrinophilus porphyriticus: aquatic larvae (+); semi-aquatic adults (+). Desmognathus ochrophaeus: aquatic larvae (+); terrestrial adults (-). Plethodon cinereus: terrestrial adults (-). These studies show that only aquatic life stages are electroreceptive, even if this sensitivity is temporarily lost in an intermediate life stage, as demonstrated in newts, Notophthalmus. In order to include most of the other families of salamanders, additional studies will need to be conducted in the Southeast (Sirenidae, Amphiumidae) and the Pacific Northwest (Dicamptodontidae, Rhyacotritonidae) plus one remaining family in New York (Cryptobranchidae).

IMPACT: 1999-10-01 TO 2004-09-30 Salamanders are key elements in many terrestrial and aquatic ecosystems and, in terms of relative biomass, are sometimes the dominant predators. Understanding the environmental cues to which salamanders respond is an important facet of their biology. This research will help to predict disruptive effects of stray voltages (which are often present in agricultural environments).

PUBLICATION INFORMATION: 1999-10-01 TO 2004-09-30
No publications reported this period

PROJECT CONTACT INFORMATION
NAME: Coffman, W. R.
PHONE: 607-255-2224
FAX: 607-255-9499