The invertebrate infauna of four Thalassia testudinum beds and
adjacent open sand areas in northern Biscayne Bay, Florida, were
sampled in July and December 1976. A total of 109 species, including
5804 individuals, were collected. Thalassia beds were found to harbor
a denser and more diverse fauna than open sand sites. This may be
attributed to increased food availability in the form of detrital
Thalassia and concealment from predators provided by the plant blades.
The most abundant species in the Thalassia beds included the polychaete
Cirriformia filigera, the amphipod Lembos smithii, and the isopod
Janira minuta. The most abundant species in the open sand areas were
the polychaetes Exogone dispar and Hesionura elongata, and the isopod
Xenanthura brevitelson. High within -site (grass or sand) faunal
similarity values and low between-site similarity values indicate the
presence of distinct communities associated with Thalassia and
adjacent open sand areas.