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Puerto Rico & Vieques 2008 Cruise, day five: March 30, 2008
Hurray for Habitat!
and manatee
grass bed (Credit:
Guiseppe DiCarlo)
Seagrasses
The coastal waters of Puerto Rico are home to a number of seagrass species, including Thalassia testudinum (turtle grass), Syringodium filiforme (manatee grass), Halodule wrightii (shoal grass), and Halophila decipiens (paddle grass). Yes, turtles do eat turtle grass and manatees do eat manatee grass. Manatees are often destructive during foraging, bull–dozing through an area removing not only green blades and stalks, but also below–ground root material. Turtles are a bit more refined in their eating habits. Turtles crop seagrass blades at the base of the shoot leaving behind a meadow that looks as if someone ran over it with a lawn mower.
(Credit: Brian
Degan)
Algae
The algae fields that we have encountered have been dominated by three species of green algae, Udotea flabellum (mermaid’s fan), Penicillus pyriformis (flat–top bristle brush), and Halimeda incrassata (three–finger leaf alga). These species of green algae are stalked and calcified, producing rigid and erect plants. It is common to find these species intermixed with seagrass.
coral (Credit:
Amy V. Uhrin)
coral reef
(Credit: Amy V.
Uhrin)
Reefs
Most of our reef sites have been low relief, mixed reefs where the seafloor is colonized by small stony corals, large gorgonians and sponges, and small amounts of algae. Stony corals secrete a hard calcium carbonate skeleton, forming the basic building blocks of tropical coral reefs. The grooved brain coral, Diploria labyrinthiformis, forms hemispherical heads with deep trough–like grooves. This species is a common reef–building species. Gorgonians do not have a rigid skeleton and are therefore commonly referred to as "soft corals." Sea fans and sea rods are types of gorgonians. This giant barrel sponge (Xestospongia muta) is a species frequently encountered in our soft coral reef habitats. Padina boergesenii is a brown alga that attaches to rocky substrates in most reef environments. Perhaps the most notable feature on this species is the concentrically banded blades. P. boergesenii is quite common at our reef sites.
Padina boergesenii (Credit: Amy V. Uhrin) Click to enlarge |
