1987 0 
Virnstein, R. W. (1987) Seagrass-associated invertebrate communities of the southeastern 
USA: a review. Fla. Mar. Res. PubL 42:89-116. 
[DATE OF SAMPLING UNKNOWN OR NOT APPLICABLE.] Community structure of 
invertebrates associated with seagrasses in the southeastern United States is 
intensively studied and well described at a few sites, but generally is not well 
understood. A high regional diversity exists, due to the overlap of subtropical, tropical 
(Caribbean), and warm-temperate (Carolinian) faunas. Decapod crustaceans, especially 
the caridean shrimps, numerically dominate the larger (trawl susceptible) fauna. 
Dominant species of decapods are similar throughout most of the region. Community 
structure of smaller macrofauna (emphasized in this review) is dynamic. Species 
composition (dominant species) and density vary widely over small and large distances 
and over short (hours to days) and long (years) time scales. Dominant higher taxa are 
peracarid crustaceans (especially amphipods), gastropod mollusks, and polychaete 
worms. Important controlling physical factors are sediments (for the infauna) and 
habitat complexity (for the epifauna). The latter is determined largely by seagrass 
density, which is best measured in terms of plant surface area. Seagrasses exert their 
influence primarily by providing physical structure to the habitat. Additional physical 
structure is provided by drift algae and epiphytes; the latter is especially important 
for smaller macrofauna and meiofauna. Predation, especially by pinfish and pink 
shrimp, is thought to be the major biological interaction affecting community structure. 
Evidence for the importance of predation comes from feeding studies, correlations of 
invertebrate abundance with predator abundance in the field, and predator exclusion and 
inclusion caging studies. Competition affects micro-distribution of two shrimp species, 
but the effects of competition, habitat selectivity, food supply, migrations, behavior, 
reproduction, and recruitment have received little attention. Two major functions of 
seagrass meadows are the provision of food and of refuge; together, these constitute 
the ’nursery* function. Epiphytes, not detritus or living seagrass tissue, provide the 
major source of food for the invertebrates. Small invertebrates are important prey for 
most abundant species of fish and decapod crustaceans. Some species of decapods are 
herbivores, however, and decapods cannot be lumped into a single trophic category. The 
degree of refuge provided by seagrasses depends on the relationships between, and 
characteristics of, habitat, predator, and prey. 
1987 0 
Zieman, J. C. (1987) A review of certain aspects of the life, death, and distribution of the 
seagrasses of the southeastern United States 1960 - 1985. Fla. Mar. Res. PubL 42:53-71. 
[DATE OF SAMPLING UNKNOWN OR NOT APPLICABLE.] Seagrass meadows are among the 
richest and ecologically most important coastal habitats. In the United States, the 
greatest seagrass resources are along the south and west coasts of Florida, with over 
5,500 km 2 of seagrass in south Florida, and a second extensive bed covering over 
3,000 km 2 between Tampa and Apalachee Bay. Well developed seagrass meadows occur 
at depths over 10 m in clear waters, but are often limited to less than 2 m in turbid, 
polluted estuaries. In these latter areas, suspended particulate matter, as well as 
overgrowths of epiphytic algae, brought about by excess nutrients in the water column, 
can stress the seagrasses. In more pristine waters, seagrasses maintain high 
productivity by obtaining nutrients from the sediments via extensive root and rhizome 
systems, which, coupled with the current-baffling effect of the leaf canopy, protect 
and stabilize the sediments. In turbid, shallow seagrass systems, much of the food web 
is based on epiphytic algal grazing, but the dominant trophic pathway in most seagrass 
systems seems to be via the detrital food web. Seagrass leaves are a relatively rich 
food source, compared to saltmarsh plants and mangroves, but are grazed directly by 
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