Benthic Macrofaunal Communities Research Articles

Benthic macrofauna communities in the German Bight : Salzwedel, Horst, Eike Rachor and Dieter Gerdes, 1985. Veröff. Inst. Meeresforsch. Bremerh., 20(2):199–267. Procopa-IMARPE, Apt 22, Callao, Peru

Benthic macrofauna communities in the German Bight : Salzwedel, Horst, Eike Rachor and Dieter Gerdes, 1985. Veröff. Inst. Meeresforsch. Bremerh., 20(2):199–267. Procopa-IMARPE, Apt 22, Callao, Peru

COMMUNITY INTERACTIONS OF CAPRELLA PENANTIS LEACH (CRUSTACEA: AMPHIPODA) ON SEA WHIPS

Sea whips, Leptogorgia virgulata L., occurring in Thalassia testudinum (Konig) meadows in northwestern Florida support an epifaunal community which is dominated by the caprellid amphipod Caprella penantis Leach. Caprella penantis densities were 23 times greater when T. testudinum died back during the winter than when T. testudinum was more dense. Observations made during seasonal collections indicate that most fish predators of C. penantis are absent during the winter. Caprella penantis densities may have been decreased by fish predation, but the density increases were due to reproductive output. When C. penantis densities on sea whips decreased, postlarval and juvenile decapod crustaceans colonized the sea whip. The reptantians remained on the sea whips through several molts and then dropped from the sea whips to join the benthic macrofaunal community. Epibiotic communities, therefore, have been demonstrated to be involved in at least three important marine ecosystems processes: (1) they serve as a concentrated and recognizable food source for nekton, (2) epibionts graze periphyton and detritus from the biotic substratum, thereby preventing smothering, and (3) some benthic invertebrates temporarily join the epibiotic community during their transition from planktonic to epibenthic life styles. Sessile and sedentary marine macroscopic organisms are common features of marine and estuarine environments, and these organisms act as a substratum for numerous epibiotic organisms (Coe, 1937; Colman, 1939; Dahl, 1948). Dean (1981) correlates species diversity of these epibiotic communities with the structural complexity of the sessile community. He attributes the positive relationship to specific habitat preferences by the epibionts. Logic supports Dean's (1981) suggestion because habitat selectivity by the epibionts is generally attributed to food availability and camouflage (Nagle, 1968; Keith, 1971; Hughes, 1978; Caine, 1979a, 1980). When confined to consideration of fouling organisms that have similar morphology, Dean's (1981) hypothesis also suggests the possible presence of parallel epibiotic communities. Comparison of epibiotic communities of sea grasses indicates that the epibiotic communities are parallel, regardless of the sea grass species (Kikuchi, 1966; Ledoyer, 1966, 1969; Nagle, 1968; Kikuchi and Peres, 1977). Thorson (1955) postulated that parallel communities should function similarly, with analogous species conducting similar activities. The global presence of analogous communities may also indicate similar interactions of the epibiotic communities with their biotic substrata and within their ecosystem. Caprellid amphipods are ubiquitous epibionts which frequently are numerically dominant within epibiotic communities. Studies conducted in Puget Sound, Washington (U.S.A.), which concentrated on activities of caprellid amphipods of the genus Caprella, showed that: (1) sea grass epibionts serve as a food source for surrounding benthic and pelagic communities, especially for juvenile fish, i.e., as nursery grounds (Caine, 1979a), and (2) some epibionts (e.g., Caprella laeviuscula), may remove fouling organisms and detritus from the biotic substratum, thereby preventing smothering of the substratum (Caine, 1980). In this paper I report on activities and community interactions of Caprella penantis Leach from the gorgonian Leptogorgia virgulata L. in northwestern Florida (Gulf of Mexico). My focus was to determine the applicability of the Puget Sound generalities to distant communities.

Benthic macrofaunal communities in the Tuggerah lakes, New South Wales

<P>The benthic macrofaunal communities of the Tuggerah Lakes were sampled using a diver-held corer. Communities were separated using DIVINF and MULCLAS classification techniques and the structure of the communities assessed using species number, diversity and evenness indices. Community structure was closely related to habitat type, seagrass substrates providing the greatest diversity compared with both mud and sand substrates. A flood during the sampling period affected the mud sites to a larger extent than seagrass sites, causing a decline in both species number and diversity. An effect of thermal power station effluent on shallow water community structure was observed and the implications of this are discussed.</P>

Salinity stratified benthic macrofaunal communities and long-term monitoring along the west coast of Sweden

Benthic macrofauna was quantitatively sampled in 12 coastal areas along the west coast of Sweden in 1971–1976. The Baltic Current creates a halocline at ≈15m depth which acts as a barrier between two differently structured benthic communities, one of which has a wide extension along the coast below the halocline and the other above the halocline. Physical and chemical factors, e.g., variations in salinity and temperature, have a great influence on the faunal structure above the halocline, whereas biological processes are the main determinating factors of the faunal composition in the comparatively more stable environment below the halocline. The sub-halocline community contains significantly more species (60%), a significantly higher mean abundance (4200 compared with 2000 ind. m −2) and a significantly greater mean biomass (146 compared with 71 g m −2 wet wt) than that above the halocline. Diversity measured by the Shannon-Wiener formula and its evenness had approximately the same means in both these habitats, 3.3–3.7 and 0.62, respectively. Four of the areas investigated in 1976 were also studied in the 1920's by approximately the same methods. The number of species, abundance, and biomass were significantly greater in the recent samples than in those taken half a century ago. and the community structures differed between the two periods. These differences are attributed to seasonal and natural long-term changes and different methods in processing the samples obtained. It is concluded that the halocline is a habitat divider and creates a vertical discontinuity for benthic communities on the west coast of Sweden.

Salinity stratified benthic macrofaunal communities and long-term monitoring along the west coast of Sweden : Rosenberg, Rutger and Peter Moller, 1979. J. expl mar. Biol. Ecol., 37(2): 175–203

Salinity stratified benthic macrofaunal communities and long-term monitoring along the west coast of Sweden : Rosenberg, Rutger and Peter Moller, 1979. J. expl mar. Biol. Ecol., 37(2): 175–203

Benthic macrofaunal dynamics, production, and dispersion in an oxygen-deficient estuary of west Sweden

The salinity above the halocline (13–15 m) in the Byfjord estuary is ≈ 23–30‰. Below the halocline the oxygen concentration diminishes abruptly and below 15–20 m the water is anoxic. The benthic macrofaunal communities were studied during 1971–1973 from 5 m down to the anoxic and afaunal bottoms. Number of species, abundance, and biomass were estimated in different strata in the sediments (0–5, 5–10 cm) and the seasonal variation was studied. The benthic faunal structure at different localities has been compared by means of a percentage similarity index and a number of diversity indices. Dispersion was assessed by the variance/mean ratio for different block sizes and the production over one year was estimated.

Changes in the epibenthos of Saldanha Bay, South Africa, between the 1960s and 2001: an analysis based on dredge samples

Saldanha Bay, which lies on the south-west coast of South Africa, has undergone major development over the past 30 years, including breakwater and harbour construction, harbour extension, dredging, mining, fishing, fish processing and mussel culture. This study examines whether the benthic macrofaunal communities in the bay have been altered over this period. Twelve stations that had been sampled in the 1960s, prior to harbour construction, were re-sampled in 2001 (40 years later) with a surface dredge. Species abundances were coded from 1 (present) to 5 (abundant) to make the two sets of samples comparable. The benthic communities before harbour development were significantly different from those in 2001 (ANOSIM, p < 0.001). Increases in the abundances of the whelk Nassarius speciosus and the crab Hymenosoma orbiculare were mainly responsible for these differences. Two main benthic communities were recognised in the 1960s and, at that stage, covered large extents of the bay, whereas in 2001 the communities were divided into distinct 'Small Bay' and 'Big Bay' groups, reflecting the division of the bay into two areas by the development of a harbour wall. Although natural fluctuations may account for some of these changes, it is more likely that the considerable anthropogenic activities within Saldanha Bay, which are known to have altered physical conditions, have led to the changes observed in the benthic communities.