Structure Of Marine Benthic Communities Research Articles

Influence of seabird colonies and other environmental variables on benthic community structure, Lancaster Sound Region, Canadian Arctic

The Canadian Arctic shelters millions of seabirds each year during the breeding season. By the excretion of important quantities of guano, seabirds locally concentrate nutrient-rich organic matter in the marine areas surrounding colonies. Seabirds, acting as biological vectors of nutrients, can markedly affect terrestrial ecosystems, but their influence on the structure of marine benthic communities is still under-studied. Sessile and long-lived megabenthic species can integrate environmental variation into marine food webs over long time frames. The objectives of this study were (1) to characterize the epifaunal and infaunal communities of the Lancaster Sound Region (LSR) and (2) to test the influence of the presence of seabird colonies and other environmental parameters on the structure of those benthic communities. Our prediction was that benthic diversity, number of taxa, total biomass of infauna and total density of epifauna and infauna, would be higher in areas with colonies present. Photos of the seafloor (data on epifauna) and grab samples (data on infauna) were taken at three control areas and at five areas near seabird colonies, within a depth range of 122 to 442m. A database of 26 environmental parameters was built to study the environment-benthos relationships. Infauna, which was relatively uniform across the LSR, was numerically dominated by Annelida. Epifauna was much patchier, with each study area having unique epibenthic assemblages. Brittle stars were highly abundant in epifaunal communities, reaching 600 individuals per square meter. The presence of seabird colonies was not a major driver of benthic community structure in the LSR at the depths studied. Negative effects of colonies were detected on the density and number of taxa of infauna, perhaps due to top-down effects transmitted by the seabirds which feed in the water column and can directly reduce the quantity of food reaching the seabed. Sediment concentration of pigment, percent cover of gravel and boulders, depth, temperature and duration of open water explained a substantial part of the observed variation across the LSR. Food availability, as expressed by sediment pigment concentration, is a factor driving benthic communities, even if potential pathways through seabirds did not broadly affect the benthos at the point source.

Effects of seawater acidification on a coral reef meiofauna community

Despite the increasing risk that ocean acidification will modify benthic communities, great uncertainty remains about how this impact will affect the lower trophic levels, such as members of the meiofauna. A mesocosm experiment was conducted to investigate the effects of water acidification on a phytal meiofauna community from a coral reef. Community samples collected from the coral reef subtidal zone (Recife de Fora Municipal Marine Park, Porto Seguro, Bahia, Brazil), using artificial substrate units, were exposed to a control pH (ambient seawater) and to three levels of seawater acidification (pH reductions of 0.3, 0.6, and 0.9 units below ambient) and collected after 15 and 30 d. After 30 d of exposure, major changes in the structure of the meiofauna community were observed in response to reduced pH. The major meiofauna groups showed divergent responses to acidification. Harpacticoida and Polychaeta densities did not show significant differences due to pH. Nematoda, Ostracoda, Turbellaria, and Tardigrada exhibited their highest densities in low-pH treatments (especially at the pH reduction of 0.6 units, pH 7.5), while harpacticoid nauplii were strongly negatively affected by low pH. This community-based mesocosm study supports previous suggestions that ocean acidification induces important changes in the structure of marine benthic communities. Considering the importance of meiofauna in the food web of coral reef ecosystems, the results presented here demonstrate that the trophic functioning of coral reefs is seriously threatened by ocean acidification.

Diversity and Distribution Patterns in High Southern Latitude Sponges

Sponges play a key role in Antarctic marine benthic community structure and dynamics and are often a dominant component of many Southern Ocean benthic communities. Understanding the drivers of sponge distribution in Antarctica enables us to understand many of general benthic biodiversity patterns in the region. The sponges of the Antarctic and neighbouring oceanographic regions were assessed for species richness and biogeographic patterns using over 8,800 distribution records. Species-rich regions include the Antarctic Peninsula, South Shetland Islands, South Georgia, Eastern Weddell Sea, Kerguelen Plateau, Falkland Islands and north New Zealand. Sampling intensity varied greatly within the study area, with sampling hotspots found at the Antarctic Peninsula, South Georgia, north New Zealand and Tierra del Fuego, with limited sampling in the Bellingshausen and Amundsen seas in the Southern Ocean. In contrast to previous studies we found that eurybathy and circumpolar distributions are important but not dominant characteristics in Antarctic sponges. Overall Antarctic sponge species endemism is ∼43%, with a higher level for the class Hexactinellida (68%). Endemism levels are lower than previous estimates, but still indicate the importance of the Polar Front in isolating the Southern Ocean fauna. Nineteen distinct sponge distribution patterns were found, ranging from regional endemics to cosmopolitan species. A single, distinct Antarctic demosponge fauna is found to encompass all areas within the Polar Front, and the sub-Antarctic regions of the Kerguelen Plateau and Macquarie Island. Biogeographical analyses indicate stronger faunal links between Antarctica and South America, with little evidence of links between Antarctica and South Africa, Southern Australia or New Zealand. We conclude that the biogeographic and species distribution patterns observed are largely driven by the Antarctic Circumpolar Current and the timing of past continent connectivity.

Utility of a spatial habitat classification system as a surrogate of marine benthic community structure for the Australian margin

Abstract Przeslawski, R., Currie, D. R., Sorokin, S. J., Ward. T. M., Althaus, F., and Williams, A. 2011. Utility of a spatial habitat classification system as a surrogate of marine benthic community structure for the Australian margin. – ICES Journal of Marine Science, 68: 1954–1962. This study tests whether a continental-scale classification of Australian benthic habitats (termed “seascapes”) and the interpolated environmental data from which they are derived are useful as abiotic surrogates of biodiversity at a local [tens of kilometres, Great Australian Bight (GAB)] and regional scale [hundreds of kilometres, Western Australian (WA) margin]. Benthic invertebrate community structure is moderately associated with specific seascapes in both the GAB (R = 0.418) and WA margin (excluding hard substrata, R = 0.375; all substrata, R = 0.313). Mud content, seafloor slope, and seafloor temperature are significantly correlated with invertebrate communities at both scales, with disturbance and primary production correlated with GAB communities. Seascapes are not consistently useful surrogates because the strength and significance of relationships between seascapes and community structure differs among seascapes, regions, and spatial scales. Nevertheless, a national system of seascapes is an appropriate surrogate for broad-scale benthic invertebrate community patterns when biological data are limited, provided the uncertainty is acknowledged and, where possible, an assessment made of each seascape's ability to differentiate biological communities. Further refinement of seascape derivations may include updated and additional environmental data (particularly for hard vs. soft substrata) and validation among biological datasets from a range of habitats and scales.

Skeletal mineralogy and biodiversity of marine invertebrates: size matters more than seawater chemistry

AbstractIt is now well established that seawater chemistry, as well as influencing non-skeletal marine precipitation (‘calcite’ and ‘aragonite seas’), has affected skeletal mineral secretion in some algal and marine invertebrate groups. Skeletal mineralogy has had a yet more profound consequence on fossil preservation. The realization that the fossil record of marine organisms with an aragonite shell is widely depleted in some shelf settings through early, effectively syn-depositional, dissolution (‘missing molluscs’ effect) has led to a re-evaluation of the composition, diversity, ecological and trophic structure of marine benthic communities. Comparisons of molluscan lagerstätten from ‘calcite’ and ‘aragonite seas’ show a similar pattern of skeletal mineralogical loss, that is, no differences are discernibly linked to changed seawater geochemistry. It is notable that the rare mollusc-rich skeletal lagerstätten faunas in the fossil record include many small individuals. Micromolluscs are quantitatively important among modern shell assemblages, yet small size is a major source of taphonomic and biodiversity loss in the fossil record. In skeletal lagerstätten faunas, micromolluscs contribute variably to mollusc biodiversity but appear particularly significant through at least to Triassic times. They highlight a further ‘missing molluscs’ effect of taphonomic loss through early dissolution.

On the origin of Antarctic marine benthic community structure

Environmental conditions fostering marine communities around Antarctica differ fundamentally from those in the rest of the world's oceans, particularly in terms of pronounced climatic fluctuations and extreme cold. Here, we argue that the rarity of pelagic larval stages in Antarctic marine benthic invertebrate species is a consequence of evolutionary temperature adaptation and that this has greatly contributed to the current structure of the Antarctic benthic community. In arguing this position, we challenge the likelihood of previously suggested survival strategies of benthic communities on the Antarctic continental shelf and slope during Cenozoic glacial periods. By integrating evidence from marine geology and geophysics, we suggest that the Antarctic continental shelf and slope were both unfavourable environments for benthic communities during glacial periods and that community survival was only possible in the deep sea or in shelters on the continental shelf as a result of the diachronism in maximum ice extent.

A juvenile recruitment prediction model for Ruditapes decussatus (L.) (Bivalvia: Mollusca)

Despite the importance of larval abundance in determining the recruitment of benthic marine invertebrates and as a major factor in marine benthic community structure, relating planktonic larval abundance with post-settlement post-larvae and juveniles in the benthos is difficult. It is hampered by several methodological difficulties, including sampling frequency, ability to follow larval and post-larval or juvenile cohorts, and ability to calculate growth and mortality rates. In our work, an intensive sampling strategy was used. Larvae in the plankton were collected at weekly intervals, while post-larvae that settled into collectors were analysed fortnightly. Planktonic larval and benthic post-larval/juvenile cohorts were determined, and growth and mortality rates calculated. Integration of all equations allowed the development of a theoretical formulation that, based on the abundance and planktonic larval duration, permits an estimation of the future abundance of post-larvae/juveniles during the first year of benthic life. The model can be applied to a sample in which it was necessary only to measure larval length.

Identification of global and local components of spatial structure of marine benthic communities: example from the Bay of Seine (Eastern English Channel)

Data from samples of the macrobenthic Abra alba– Pectinaria koreni community of the eastern Bay of Seine (English Channel) collected in winter 1986 are analysed to illustrate the advantages of a novel method of multivariate analysis of spatial patterns described by Thioulouse et al. (Environ. Ecol. Stat., 2 (1995) 1–14), consisting of local and global approaches. Multivariate ordination procedures are applied that take spatial components into account explicitly through the construction of a neighbourhood graph between closely placed sampling sites, which is then used to weight the data. The result is a decomposition of spatial structure on local and global scales. This method is for the first time applied to macrobenthic data of this region. It shows the underlying importance of spatial scaling in analysis and proves to offer more information than classical ordination methods such as correspondence analysis, which may confuse the two different spatial scales. Global analysis is proposed as a powerful tool to define species assemblages and local analysis as an additional instrument to define partitions resulting from biological interactions. Additionally, this method appears capable of incorporating rare species (which influence classical analyses, often resulting in their elimination from datasets) by minimising their effects on the global scale and conversely maximising them on the local scale. This analysis demonstrates the importance of explicitly incorporating spatial information into the detection and interpretation of patterns in a macrobenthic community.

Organism–quartz interactions in structuring benthic communities: towards a marine bio‐mineralogy?

Abiotic and biotic factors determine the distribution and structure of marine benthic communities but the processes invoked to explain such patterns are often inadequate. We demonstrate that the presence of quartz grains in sediments inhibits animal colonization on marine soft‐bottoms. We suggest that this phenomenon may be related to the oxidant properties of the quartz crystal surface derived by the generation of silicon‐based radicals due to water movement. The interaction between organisms and the crystallographic structure of substrata might play a neglected but important role in structuring coastal benthic communities.

Weight of the Evidence is the Right Approach

Sampling and field experiments were conducted from 1975 to 1990 to test how the structure of marine benthic communities around McMurdo Station, Antarctica varied with levels of anthropogenic contaminants in marine sediments. The structure of communities (e.g., infauna density, species composition, and life history characteristics) in contaminated and uncontaminated areas were compared with the structure of communities influenced by two large‐scale natural disturbances, anchor ice formation and uplift or iceberg scour. Benthic communities changed radically along a steep spatial gradient of anthropogenic hydrocarbon, metal, and PCB contamination around McMurdo Station. The heavily contaminated end of the gradient, Winter Quarters Bay, was low in infaunal and epifaunal abundance and was dominated by a few opportunistic species of polychaete worms, especially Capitella spp., Ophryotrocha claperedii, and Gyptis sp. These are relatively small and motile species. Closely related species live in organically enriched and anthropogenically disturbed sediments throughout temperate latitudes. The edge of the heavily contaminated bay, the transition area, contained several motile polychaete species with less opportunistic life histories, especially Tharyx sp. and Haploscoloplos kerguelensis. Uncontaminated sedimentary habitats harbored dense tube mats of infaunal animals numerically dominated by populations of polychaete worms, crustaceans, and a large suspension feeding bivalve. These species are generally large and relatively sessile, except for several crustacean species living among the tubes. Community patterns along the anthropogenic disturbance gradient were similar to community changes along a natural gradient of anchor ice disturbance. The same motile and opportunistic polychaete worms were most abundant where anchor ice freezing and uplift were most severe. The motile polychaetes, Tharyx sp., Haploscoloplos kerguelensis, and Polygordius sp., were abundant at the edge of the anchor ice disturbance zone. The undisturbed bottom harbored the same dense tube mat community and large bivalve population. Community changes along the anthropogenic disturbance gradient were also similar to colonization patterns into bottom areas gouged by icebergs. The most recent ice gouges along the east side of McMurdo Sound contained large numbers of the motile opportunistic polychaete worms. Ice gouges along the western sound contained more motile species of infauna compared to adjacent undisturbed bottoms with large numbers of tube‐dwelling infauna. Motile species were also the first to colonize experimental sediments placed on the sea floor for 6 yr. Although the community patterns around anthropogenic and natural disturbances were similar, particularly the motile and opportunistic species at heavily disturbed and marginal areas, the natural disturbances cover much greater areas of the sea floor around the entire Antarctic continent. On the other hand, recovery from chemical contamination is likely to take many more decades than recovery from natural disturbances as contaminant degradation is a slow process. This process can be enhanced by ongoing pollution abatement and cleanup operations.

Long-term changes in the benthic community on the coastal shelf of Palos Verdes, Southern California

Between 1972 and 1982, both wastewater discharge and natural perturbations played important roles in directing marine benthic community structure on the Palos Verdes Shelf in Southern California, USA. Community succession was traced along a gradient of eleven 60 m-depth stations extending from the submarine outfalls. Spatial and temporal biological patterns were identified via direct gradient, clustering and principal-coordinates analyses. Species associations which occupied sites distant from the outfalls in the early 1970s gradually became established closer to the diffusers during the decade. The areal extent of outfall impacts shrank, reflecting both improvements in effluent quality and co-occurring beneficial natural events, specifically the short-term settlement of large numbers of the echiuran Listriolobus pelodes.

Fluid and Sediment Dynamic Effects on Marine Benthic Community Structure

Fluid and sediment dynamics affect benthic community dynamics and structure in manifold ways. We single out three community-structuring processes that are both strongly affected and amenable to controlled manipulation: microbial population growth, faunal recruitment, and particle feeding. Attachment and colony growth rates of microbes depend on the details of near-bed fluid exchange. Their emigration and colony growth rates are affected by erosion of microbial filmsand by abrasion during sediment transport. Recruitment and successional patterns of metazoans, especially those resulting from the settlement of weakly swimming, small larvae and juveniles, also are very sensitive to local variations in boundary layer flow pattern and strength. While the importance of particle fluxes to suspension feeders has long been apparent, the foraging patterns of a growing number of surface deposit feeders are being found to reflect a dependence upon sediment transport. Although these three processes have spatial and temporal scales amenable to both laboratory and field experimentation, proper dynamic scaling of laboratory model flows may not always be easy. Even the simplest two-phase (particles plus liquids, where particles can be bacteria, floes, larvae, or sediments) flows must match appropriate laboratory and field Reynolds number, Froude number, particle-fluid density (weight per unit volume) ratio, and the ratio of boundary layer thickness to particle size, if the laboratory flow model is to provide accurate results.

Assessment of pollution-induced changes in benthic community structure

This article presents a brief summary of three ways in which the structure of marine benthic communities have been examined in the past. These approaches are considered in terms of their usefulness in assessing or forecasting changes in marine ecosystems through physical disturbance or chemical pollutants. No attempt has been made to review all pertinent literature. Rather, an overview of approaches is presented with comments on limitations and possibilities of these types of study for assessment of long and short-term changes in marine benthic environments.