Experiments on Competition and Predation Among Shrimps of Seagrass Meadows

Abstract

A series of experiments was conducted to evaluate the distribution and abundance patterns of two species of macrophyte-inhabiting caridean shrimps found in Apalachee Bay, Florida, USA. Experiments using Palaemonetes vulgaris and Palaemon jloridanus included microhabitat association and behavioral interactions. Predator-prey relationships, as they apply to habitat complexity and interspecific interactions, were also examined using the pinfish, Lagodon rhomboides, a natural predator.Pt. vulgaris individuals were excluded from the experimental habitats by P. floridanus over a range of densities. We conclude that their nonoverlapping microgeographical distribution is primarily a consequence of interspecific competition rather than just microhabitat selection. Predation success on single species was inversely related to the physical complexity of the experimental habitat. However, when placed together, a significantly greater proportion of Pt. vulgaris is consumed than P. jloridanus. We posit that the displacement of Pt. vulgaris from cover by P. floridanus significantly increases the former's risk of detection and capture. The importance of refuges in regard to: (I) seagrass predator strategies; (2) prey tactics, and (3) species abundance and richness patterns in macrophyte-dominated communities are discussed.

Effects of propeller scarring on macrofaunal use of the seagrass Thalassia testudinum

“…Other species, such as caridean shrimp, are known to select vegetation over bare substrates (Ewald 1969, Barry 1974, Coen et al 1981. Considering that scarring removes habitat (and shelter), shrimp probably emigrated to seagrass surrounding the scars or failed to immigrate into scar areas.…”

Fish and macrocrustacean use of submerged plant beds in tidal freshwater marsh creeks

“…Heck & Thoman (1984) found no significant correlation between fish abundance and plant biomass in a Ruppia bed but decapod abundance was correlated with Ruppia biomass. Structural complexity may be the most important factor influencing the use of SAV (Heck & Orth 1980, Coen et al 1981. Compared to most seagrasses, the dominant species of SAV in tidal freshwater environments (i.e.…”

“…Recent laboratory and field studies of estuarine (Nelson 1979, Coen et al 1981, Heck & Thoman 1981 and freshwater , Crowder & Cooper 1982, Savino & Stein 1982 habitats have shown that SAV provides protection to small fishes and invertebrates by reducing the foraging efficiency of large predators. Similarly, SAV likely provides a n important subtidal refuge for the juveniles and small species that occupy tidal freshwater marsh creeks.…”

“…A number of laboratory and field studies have shown that SAV functions as a refugium and foraging area for many associated fauna (Nelson 1979, Coen et al 1981, Heck & Thoman 1981, Crowder & Cooper 1982, Savino & Stein 1982, Werner et al 1983, Gilinsky 1984, Watanabe 1984, Leber 1985. Because these aquatic habitats afford protection from predation and provide foraging sites, they are generally recognized as valuable nursery areas for juvenile fishes and decapods (Thayer et al 1978).…”

Predation on postlarvae and juveniles of the shore crab Carcinus maenas:importance of shelter, size and cannibalism

“…Qualitative observation made in glass aquaria showed that the first instar crabs could move in-between filaments, where they were well concealed and out of reach of the larger predators. The brown shrimp often got entangled in the filaments, resulting in abdominal (caridoid) reflex (Coen & Heck 1981) and interrupted search activity. Enteromorpha and Cladophora species make up over 90% of the biomass of ephemeral algae that intermittently cover up to 50 % of all shallow bays (0 to 1 m) on the west coast of Sweden during the summer (June to September; Moksnes & Pihl1995).…”