The BenBioDen database, a global database for meio-, macro- and megabenthic biomass and densities.

Benthic fauna refers to all fauna that live in or on the seafloor, which researchers typically divide into size classes meiobenthos (32/64 µm-0.5/1 mm), macrobenthos (250 µm-1 cm), and megabenthos (>1 cm). Benthic fauna play important roles in bioturbation activity, mineralization of organic matter, and in marine food webs. Evaluating their role in these ecosystem functions requires knowledge of their global distribution and biomass. We therefore established the BenBioDen database, the largest open-access database for marine benthic biomass and density data compiled so far. In total, it includes 11,792 georeferenced benthic biomass and 51,559 benthic density records from 384 and 600 studies, respectively. We selected all references following the procedure for systematic reviews and meta-analyses, and report biomass records as grams of wet mass, dry mass, or ash-free dry mass, or carbon per m2 and as abundance records as individuals per m2. This database provides a point of reference for future studies on the distribution and biomass of benthic fauna.

Distribution, inventory and turnover of benthic organic biomass in the Strait of Georgia, Canada, in relation to natural and anthropogenic inputs.

Recently compiled databases facilitated estimation of basin-wide benthic organic biomass and turnover in the Strait of Georgia, an inland sea off western Canada. Basin-wide organic biomass was estimated at 43.1 × 10(6) kg C and production was 54.6 × 10(6) kg Cyr(-1), resulting in organic biomass turnover (P/B) of 1.27 × yr(-1). Organic biomass and production for sub-regions were predictable from modified organic flux (r(2)>0.9). P/B declined significantly with increasing modified organic flux, suggesting greater biomass storage in high flux sediments. Biomass and production were highest, and P/B lowest near the Fraser River. Annual basin-wide benthic production was 60% of previously estimated oxidized organic flux to substrates, which agrees with proportional measurements from a recent, localized study. Deviations from expected patterns related to organic enrichment and other stressors are discussed, as are potential impacts to benthic biomass and production, of declining bottom oxygen, increasing bottom temperature and potential changes in riverine input.

Distribution and uptake of key polychlorinated biphenyl and polybrominated diphenyl ether congeners in benthic infauna relative to sediment organic enrichment.

As part of a broader study of budgets, transport, and bioaccumulation of persistent organic contaminants in the Strait of Georgia, Canada, matching samples of sediment and bulk benthos were collected near two marine sewage outfalls, two large urban harbours, and background areas. Samples were analyzed for polychlorinated biphenyl (PCB) and polybrominated diphenyl ether (PBDE) congeners. We present data for those congeners that fell within the top six rankings by concentration (23 PCBs and 10 PBDEs) within at least one of the environmental media measured in other studies (air, water, sediments, benthos, pelagic biota). Multifactor regression analyses incorporating sediment characteristics (total organic carbon, fines) predicted uptake (r (2) = 0.74 to 0.98, p < 0.04) over the range of congeners and habitats examined. PBDEs were taken up by biota more readily than PCBs, suggesting a large, potentially available biological reservoir of PBDEs in sediments. Dominant congeners in benthos comprised PBDEs 47, 99, 209, and 100 and PCBs 138/163, 153, 101, 118, and 110. PBDE uptake was anomalously high near one wastewater outfall, likely due to selective feeding on PBDE-enriched particulates from that source. Conversely, outfalls supply food and sediments with PCB concentrations similar to ambient sediments. However, organic enrichment of sediments near outfalls clearly enhanced PCB uptake by benthos, probably due to greatly increased biomass turnover near these sources. Data suggest there to be an initial reservoir of PCBs in newly settled juvenile benthos, which is much less evident for PBDEs. This is likely a consequence of the ecosystem-wide distribution of legacy PCBs but not the more current-use PBDEs. Congener-uptake patterns were dependent on source and input dynamics, feeding methods, and contaminant metabolism or debromination, particularly of deca-BDE.

Size structure of marine soft-bottom macrobenthic communities across natural habitat gradients: implications for productivity and ecosystem function.

Size distributions of biotic assemblages are important modifiers of productivity and function in marine sediments. We investigated the distribution of proportional organic biomass among logarithmic size classes (2(-6)J to 2(16)J) in the soft-bottom macrofaunal communities of the Strait of Georgia, Salish Sea on the west coast of Canada. The study examines how size structure is influenced by 3 fundamental habitat descriptors: depth, sediment percent fines, and organic flux (modified by quality). These habitat variables are uncorrelated in this hydrographically diverse area, thus we examine their effects in combination and separately. Cluster analyses and cumulative biomass size spectra reveal clear and significant responses to each separate habitat variable. When combined, habitat factors result in three distinct assemblages: (1) communities with a high proportion of biomass in small organisms, typical of shallow areas (<10 m) with coarse sediments (<10% fines) and low accumulation of organic material (<3.0 gC/m(2)/yr/δ(15)N); (2) communities with high proportion of biomass in the largest organisms found in the Strait, typical of deep, fine sediments with high modified organic flux (>3 g C/m(2)/yr/δ(15)N) from the Fraser River; and (3) communities with biomass dominated by moderately large organisms, but lacking the smallest and largest size classes, typical of deep, fine sediments experiencing low modified organic flux (<3.0 gC/m(2)/yr/δ(15)N). The remaining assemblages had intermediate habitat types and size structures. Sediment percent fines and flux appear to elicit threshold responses in size structure, whereas depth has the most linear influence on community size structure. The ecological implications of size structure in the Strait of Georgia relative to environmental conditions, secondary production and sediment bioturbation are discussed.

Towards predicting basin-wide invertebrate organic biomass and production in marine sediments from a coastal sea.

Detailed knowledge of environmental conditions is required to understand faunal production in coastal seas with topographic and hydrographic complexity. We test the hypothesis that organic biomass and production of subtidal sediment invertebrates throughout the Strait of Georgia, west coast of Canada, can be predicted by depth, substrate type and organic flux modified to reflect lability and age of material. A basin-wide database of biological, geochemical and flux data was analysed using an empirical production/biomass (P/B) model to test this hypothesis. This analysis is unique in the spatial extent and detail of P/B and concurrent environmental measurements over a temperate coastal region. Modified organic flux was the most important predictor of organic biomass and production. Depth and substrate type were secondary modifiers. Between 69-74% of variability in biomass and production could be explained by the combined environmental factors. Organisms <1 mm were important contributors to biomass and production primarily in shallow, sandy sediments, where high P/B values were found despite low organic flux. Low biomass, production, and P/B values were found in the deep, northern basin and mainland fjords, which had silty sediments, low organic flux, low biomass of organisms <1 mm, and dominance by large, slow-growing macrofauna. In the highest organic flux and biomass areas near the Fraser River discharge, production did not increase beyond moderate flux levels. Although highly productive, this area had low P/B. Clearly, food input is insufficient to explain the complex patterns in faunal production revealed here. Additional environmental factors (depth, substrate type and unmeasured factors) are important modifiers of these patterns. Potential reasons for the above patterns are explored, along with a discussion of unmeasured factors possibly responsible for unexplained (30%) variance in biomass and production. We now have the tools for basin-wide first-order estimates of sediment invertebrate production.

Evaluation of mine tailings effects on a benthic marine infaunal community over 29 years.

Benthic infaunal and sediment data collected over 29 years were used to examine the extent and geographic range of effects and recovery from submarine tailings deposition. Empirical data were used to determine extreme and moderate effects, and identify near-, mid- and far-field zones. A simple probability test using overlap in frequency distributions was then used to determine less obvious effects, identify "normal" or "reference" conditions, and verify the geographic range of effect zones. Tailings thickness and sediment particulate copper were elevated from the outfall to 16-20 km distant, particularly below discharge depth (50 m). Changes in tailings thickness and copper levels before, during and after mining showed three distinct impact zones below discharge depth: near-field (<5 km from outfall); mid-field (5-16 km); and far-field (20 + km). Consistent faunal declines during mining were noted at sediment particulate copper levels >300 microg g(-1), and sediment tailings thickness > 15-20 cm. Extreme impoverishment at these sediment levels were; < 100 animals/m2, <2.5 g/m2 biomass and <7 taxa per station. No stations with >300 microg g(-1) copper and 20 cm tailings had more than 40 taxa. Amphipods were particularly affected by tailings, with distributions reflecting the instability in sediments from heavy deposition and/or shifting of tailings due to resuspension. The probability testing method assumed that reference conditions existed in far-field stations. There was no difference in abundance distributions between near-, mid- and far-field zones. Total taxa per station during mining was significantly reduced (<45) in both near- and mid-field stations compared with far-field (less than 10% overlap in distributions). One midfield station in Quatsino Sound (23) was in reference condition throughout the study period. Post-closure stations in the near- and mid-field had total taxa numbers approaching far-field conditions (overlap of 62% in distributions). Within 3 years following closure, total taxa values were within the far-field range for all stations sampled. Biomass showed a distinct decline in the near-field during mining, but with more overlap in near-field and far-field distributions (27%) than for total taxa per station, and was returning to far-field conditions in the post-closure years. A multivariate (Bray-Curtis) measure of dissimilarity indicated that the near- and mid-field infaunal compositions were distinct from the far-field during mining (< 10% overlap in distributions). The mid-field composition overlapped more with the far-field in the post-closure years, but the near-field composition did not, suggesting that the mine tailings are still affecting the fauna. The most abundant taxon in each of the reference and near-field station groups both showed significantly distinct relative abundance distributions between near- and far-field stations. In summary, the probability method showed that species richness, biomass, species composition and indicator taxa were useful for differentiating affected and non-affected stations. Polychaetes recolonize stable tailings most quickly, and have dominated the tailings stations in the post-closure years. Amphipods have recolonized sporadically, but seem to be highly sensitive to tailings stability. There was no evidence of recovery in dominant bivalves or echinoderms within three years after mine closure.