Quantitative composition and distribution of the macrobenthic invertebrate fauna of the continental shelf ecosystems of the northeastern United States / Roger B. Theroux, Roland L. Wigley.

Abstract

From the mid-1950s to the mid-1 960's a series of quantitative surveys of the macrobenthic invertebrate fauna were conducted in the offshore New England region (Maine to Long Island, NewYork). The surveys were designed to 1) obtain measures of macrobenthic standing crop expressed in terms of density and biomass; 2) determine the taxonomic composition of the fauna (ca. 567 species): 3) map the general features of macrobenthic distribution; and 4) evaluate the fauna's relationships to water depth, bottom tvpe, temperature range, and sediment organic carbon content. A total of 1,076 samples, ranging from 3 to 3,974 m in depth, were obtained and analyzed. The aggregate macrobenthic fauna consists of 44 major taxonomic groups (phyla, classes, orders). A striking fact is that only five of those groups (belonging to four phyla) account for over 80% of both total biomass and number of individuals of the macrobenthos. The five dominant groups are Bivalvia, Annelida, Amphipoda, Echninoidea, and Holothuroidea. Other salient features pertaining to the macrobenthos of the region are the following: substantial differences in quantity exist among different geographic subareas within the region, but with a general trend that both densitv and biomass increase from northeast to southwest; both densitv and biomass decrease with increasing depth; the composition of the bottom sediments significantlv influences both the kind and quantity of macrobenthic invertebrates, the largest quantities of both measures of abundance occurring in the coarser grained sediments and diminishing with decreasing particle size; areas with marked seasonal changes in water temperature support an abundant and diverse fauna, whereas a uniform temperature regime is associated with a sparse, less diverse fauna; and no detectable trends are evident in the quantitative composition of the macrobenthos in relation to sediment organic carbon content.

Balancing end-to-end budgets of the Georges Bank ecosystem

“…Steimle (1987) used literature values of P:B ratios to estimate benthic production on the Bank. Total production based on the Theroux and Wigley (1998) samples is 102 kcal m -2 .yr -1 with an overall P:B ratio of 1.2 (Table 10 ). The same P:B ratios, applied to Michael et al's (1983) (Table 10).…”

“…Diet information has been compiled for 24 benthic species that are abundant on Georges Bank (Theroux & Wigley, 1998). The suspension feeders filter microplankton (diatoms, flagellates and microzooplankton) and the deposit feeders consume organic matter on sediment grains.…”

Using fish stomachs as samplers of the benthos: integrating long-term and broad scales

“…The few studies that have attempted to synoptically sample the benthos at these broad scales literally took multiple decades to sample, process, identify, audit and analyze (e.g. Kiyko & Pogrebov 1997, Theroux & Wigley 1998. Thus, it is difficult, time-consuming, and cost-prohibitive to survey benthos, let alone determine the broad-scale and long-term dynamics of benthic communities or the extent of effects on benthic communities from fishing and similar disturbances.…”

Untitled

“…The lack of daytime beam trawl sampling may have influenced our results because some species have been found to exhibit diel patterns of microhabitat use on the northeast U.S. shelf (Diaz et al, 2003); consequently additional roundthe-clock sampling may lead to the discovery of different habitat relationships than those we report here. Nevertheless, taxon-specific relationships with habitat on the shelf have previously been shown for fish and macro-invertebrates and were most closely associated with sediment characteristics (Wigely and Theroux, 1981;Theroux and Wigely, 1998;Methratta andLink, 2006, 2007), depth (in both the cross-shelf and shoal formations) (Viscido et al, 1997;Steves et al, 1999;Methratta and Link, 2007;Vasslides and Able, 2008;Slacum et al, 2010), and bottom water temperature, particularly with seasonal temperature changes (Steves et al, 1999;Malek et al, 2014). Hale (2010), in examining estuarine and near shore sample locations, also showed that salinity was related to macro-invertebrate assemblages.…”

“…3). Regional variation in assemblage structure on the northeast U.S. shelf, following a south to north gradient, has been described for both fish (Gabriel, 1992;Lucey and Nye, 2010) and macro-invertebrates (Wigely and Theroux, 1981;Theroux and Wigely, 1998;Hale, 2010). Consequently, impacts of WEAs spread along the shelf may become additive for assemblages that span large distances (i.e., 50-100 km).…”