Pelagic-benthic coupling on the shelf of the northern Bering and Chukchi Seas. II. Benthic community structure

Composition, abundance, and diversity of peracarids (Crustacea) were investigated over a period of 3 mo in the Northeast Water Polynya (NEW), off Greenland. Samples were collected from May to July 1993 during expeditions ARK IX/2 and 3 using an epibenthic sledge on RV 'Polarstern' Within the macrobenthic community peracarids were an important component of the shelf fauna and occurred in high abundance in this area together with polychaetes, molluscs and brittle stars. A total of 38322 specimens were sampled from 22 stations. Cumacea attained the highest total abundance and Amphipoda the highest d~versity. Isopoda were of medium abundance, Mysidacea less abundant, and Tanaidacea least abundant. In total 229 species were found. Differences in composition, abundance and diversity do not reflect bathymetric gradients, but mainly the availability of food (phytoplankton and especially ice algae) and, hence, the temporal and spatial opening of the polynya. Thus primary production and hydrographic condit~ons (lateral advection due to the ant~cyclonic gyre around Belgica Bank) are the main biological and physical parameters influencing the peracarid crustacean community, documenting a close coupling between primary production and the benthic community in the eastern Westwind Trough. The high abundance of Peracarida, which are also capable of burrowing in the upper sediment layers, indicates their importance for benthic carbon cycling.

Section: Discussionmentioning

confidence: 99%

Peracarid fauna (Crustacea, Malacostraca) of the Northeast Water Polynya off Greenland:documenting close benthic-pelagic coupling in the Westwind Trough

Brandt¹

1995

“…Kusnetsov 1970, Thomson 1982, Long & Lewis 1987, Grebmeier et al 1989, Feder et al 1994, Dahle et al 1998, Sejr et al 2000. In the Pechora Sea open-sea areas the environmental conditions are typically more stable than in the highly varying coastal areas, which are affected by seasonal variations in ice scouring, freshwater discharge and temperature.…”

Section: Effects Of Abiotic Factors and Sediment Typementioning

confidence: 99%

Macrozoobenthos of the Pechora Sea (SE Barents Sea): community structure and spatial distribution in relation to environmental conditions

Denisenko¹,

Денисенко²,

Lehtonen³

et al. 2003

Extensive investigations on macrozoobenthic communities of the Pechora Sea (SE Barents Sea), carried out between 1991 and 1995, indicate that it is rich in terms of diversity, with a total of 712 taxa observed (505 identified to species level). Biomass distribution of zoobenthos varied greatly (2.6 to 1200 g m -2 wet wt). Average values recorded for the offshore areas are high for an Arctic environment, implying that the influence of the large Pechora River may extend far into the offshore area. In addition, intensive sedimentation of organic matter during the retreat of the highly productive ice-edge zone in the summer may also contribute to the observed high biomass. A method combining the abundance and biomass values of species was used to calculate an index approximating the production of each species. This index was used to distinguish the different community types in the area. In the study area, 13 benthic community types were identified, of which 2 main types covered most of the offshore areas. The concentration of total organic carbon (TOC) in the sediment was shown to have a strong influence on the diversity of the benthic communities, while both TOC and water depth affected the distribution of communities and the feeding mode of the dominant species. A community type consisting of surface deposit-feeders is the most widely distributed type in the area. Suspension feeders, however, dominate an extensive shallow offshore area. Boreal-Arctic species show a marked predomination (68.9%) in the whole Pechora Sea. The share of Arctic species is greater in the northern part influenced by cold water currents, while boreal species predominate in areas affected by warmer coastal waters. These observations indicate that the Pechora Sea functions as a transitional zone between boreal and Arctic biogeographic regions.KEY WORDS: Arctic · Biogeography · Community structure · Diversity · Macrozoobenthos · Pechora SeaResale or republication not permitted without written consent of the publisher

“…In these ecosystems the spatial patterns of the communities are well known (e.g. Hughes et al 1972, Maurer & Leathem 1980, Grebmeier et al 1988, 1989. In contrast, tropical shelf ecosystems are less understood despite their quantitative significance -they comprise nearly one-third of the sea shelf.…”

Section: Introductionmentioning

confidence: 99%

Structure and dynamics of benthic megafauna on the continental shelf offshore of Ubatuba, southeastern Brazil

Pires¹

1992

125

Twelve survey cruises on the continental shelf offshore of Ubatuba, southeastern Brazil, were conducted during 1985 to 1987 as a part of a broad oceanographic investigation on the tropical Atlantic shelf ecosystem. Two different water masses influence the seabed: South Atlantic Central Water (SACW) and Coastal Water (CW). The first penetrates towards the coast during summer months, and retreats offshore in the winter. Distribution, density and biomass of the benthic megafauna show 2 domains: inner shelf and outer shelf, both separated by a front. High abundance of the brachyuran crab Portunus spinicarpus characterizes the frontal system and occasionally changes the structure of the inner and outer shelf assemblages. Mulhvariate analyses showed that water masses and sea depth are the main factors structuring the benthic megafauna comn~unities. Clustering analysis disclosed 4 dlstinct faunistic assemblages: (1) coastal communities withln the CW domain, (2) inner shelf communities influenced by a mixed zone with CW predominant, (3) frontal zone communities where SACW was predominant, (4) outer shelf communities within the SACW domain. Species diversity was almost hon~ogeneous on the entire shelf except in the frontal zone where it sharply decreased. The common species, both perenial and seasonal, showed a consistent pattern of d o m a n c e through the study period. Adjustments occur within the community whereby some species increase in abundance when others decrease, maintaining a stable pattern. A 'cyclic' stability-adjustment mechanism is proposed to explain the dynamics of the megabenthos in the Ubatuba region.