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

Abstract

Fishes and macrocrustaceans (nekton) were sampled biweekly from mid-June through October 1985 from submerged aquatic vegetation (SAV) and during September 1985 from unvegetated areas of tidal freshwater marsh creeks. Nineteen species of fishes (6918 individuals, 3.068 kg preserved wet weight) from 9 famhes, and 3 species of invertebrates (12036 individuals, 1.577 kg preserved wet weight) were collected from SAV The most abundant species were grass shrimp Palaemonetes pugio, banded killifish Fundulus diaphanus, mummlchogs F. heteroclitus, bluespotted sunfish Enneacanthus gloriosus, and mud crabs Rhithropanopeus harrisj:. Recruitment of small juvenile fishes of several species coincided with the period of greatest SAV area1 cover (late June through September). Average densities of fauna were significantly greater in SAV than over nearby unvegetated creek bottoms in September. Fauna1 abundance was not significantly related to SAV biomass, perhaps because the structural complexity of the SAV in our study area was high and nekton were abundant when SAV was present at low densities (i.e. low biomass). The numerically dominant species that occurred in SAV at low tide and on the marsh surface at high tide were similar Grass shrimp, banded lullifish, mummichogs and bluespotted sunfish accounted for > 90 % of the total number of organisms collected in each of the 2 habitats, SAV and marsh surface. The SAV of tidal freshwater marsh creeks is probably most important as habitat for forage fishes. Young of recreational species such as bluegill Lepomis macrochirus and pumpkinseed L. gibbosus also occupy this habitat.

Flume weir for quantitative collection of nekton from vegetated intertidal habitats

“…Flume weirs capture nekton from a precisely defined, but much larger area than throw traps (Kushlan 1981, Rozas & Odum 1987a, Sogard 1989 and drop traps (Zimmerman et al 1984). This should reduce the portion of sample variance attributable to gear avoidance, small-scale patchy distribution patterns and other problems associated with small sample unit size.…”

“…Active methods provide instantaneous samples from a defined area and include: lift-nets (Higer & Kolipinski 1967), drop-nets (Moseley & Copeland 1969, Adams 1976, pop-nets (Serafy et al 1988) and a variety of enclosure traps (Kushlan 1981, Zimmerman et al 1984, Rozas & Odum 1987a, Sogard 1989. Most of the active devices are portable and sample a relatively small area (1 to 9 m2).…”

Dietary Segregation of Pelagic and Littoral Fish Assemblages in a Highly Modified Tidal Freshwater Estuary

“…In the southeastern U.S. estuaries, SAV restoration is studied and promoted in regional management plans because it provides valuable habitat for many native invertebrates and fishes in those ecosystems (Orth et al 1984;Rozas and Odum 1987;Rozas et al 2005;Baldizar and Rybicki 2007). However, in the San Francisco Estuary, Brazilian waterweed and other introduced species of SAV are considered a nuisance because they impede recreational boat traffic, clog water diversions, and provide little or no economic value (California Department of Boating and Waterways 2000).…”

Correspondence between environmental gradients and summer littoral fish assemblages in low salinity reaches of the Chesapeake Bay, USA

“…For example, juvenile redbreast sunfish and pumplunseed were much more abundant and frequently captured in the SAV bed versus downstream unvegetated stations. Juvenile centrarchids are known to concentrate in the vegetated littoral zones of lakes (Werner et al 1977) and tidal freshwater marshes (Rozas & Odum 1987a). The bluespotted sunfish, a small centrarchid, appeared largely constrained to the SAV beds.…”