No abstract

Macrofaunal samples were collected seasonally from 1978 to 1995 in the subtidal zone off Norderney, one of the East Frisian barrier islands. Samples were taken with a 0.2 m' van Veen grab a t 5 sites with water depths of 10 to 20 m . Interannual variability in biomass, abundance and species number of the blota were related to interannual climate variability using multivariate regression models. Changes in the biota were described in relation to human impact and seasonal and long-term meteorological variability. Our analyses suggest that macrofaunal comnlunities are severely affected by cold winters, whereas storms and hot summers have no impact on the communiti~s It appears that mild meteorological conditions, probably actlng In conjunction with eutrophicatlon, have resulted in an Increase in total biomass since 1989 A multlvariate model found the follo~ving strong relationship: abundance, species number and [less clear) blomass in the second quarter are correlated with the North Atlantic Oscillation (NAO). The med~ator between the NAO and benthos IS probably the seasurface temperature (SST) in late wlnter and early spring. On the basis of our results, w e suggest that most of the interannual variab~l~ty 111 macrozoobenthos can be explained by climate var~ability.

The structure of North Sea benthic invertebrate and fish communities is an important indicator of anthropogenic and environmental impacts. Although North Sea fish stocks are monitored regularly, benthic fauna are not. Here, we report the results of a survey carried out in 2000, in which five nations sampled the epibenthic and fish fauna at 270 stations throughout the North Sea. The aim of the survey was to investigate the diversity and community structure of epibenthic and fish communities and to identify relationships with environmental factors, including the frequency of commercial otter and beam trawling disturbance. Epibenthic species diversity was lower in the southern North Sea than in central and northern areas. Fish, conversely, were more diverse in the south. The 50 m, 100 m and 200 m depth contours broadly defined the boundaries of benthic and fish communities. The abundance of epibenthos of the southern North Sea was dominated by free-living species, whilst north of the 50 m contour sessile species prevailed. A hybrid area, with sessile species typical of the north and free-living species characteristic of the south, was found off the Norfolk and Flamborough coast stretching towards the Dogger Bank. Large-scale hydrodynamic phenomena were most likely to be responsible for the main divisions between communities, especially the boundary between mixed and stratified water masses. However, bottom temperature, sediment parameters and beam trawling were closely correlated with species richness and diversity, as well as community patterns, and may modify regional species composition. Our study shows that effective large-scale sampling of benthic communities can be conducted during existing fisheries surveys. Since annual fisheries surveys are conducted throughout the northeast Atlantic shelf seas, concurrent benthic surveys would allow benthic sampling on unprecedented spatial and temporal scales. The samples would help to monitor the environmental impacts of trawling disturbance, climate change, pollution and other natural and anthropogenic factors

Species distribution models (SDMs) were applied to predict the distribution of benthic species in the North Sea. An understanding of species distribution patterns is essential to gain insight into ecological processes in marine ecosystems and to guide ecosystem management strategies. Therefore, we compared 9 different SDM methods, including GLM, GBM, FDA, SVM, RF, MAXENT, BIOCLIM, GARP and MARS, by using 10 environmental variables to model the distribution of 20 marine benthic species. Most of the models showed good or very good performance in terms of predictive power and accuracy, with highest mean area under the curve (AUC) values of 0.845 and 0.840, obtained for the MAXENT and GBM models, respectively. The poorest performance was shown by the BIOCLIM model, which had a mean AUC of 0.708. Nevertheless, the mapped distribution patterns varied remarkably depending on the model used, with up to 32.5% differences in predictions between models. For species with a narrow distribution range, the models showed a better performance based on the AUC than for species with a broad distribution range, which can most likely be attributed to the restricted spatial scale and the model evaluation procedure. Of the environmental variables, bottom water temperature and depth had the greatest effect on the distribution of 14 benthic species, based on MAXENT results. We examine the potential utility of this strategy for predicting future distribution of benthic species in response to climate change.

Explaining patterns of commonness and rarity is fundamental for understanding and managing biodiversity. Consequently, a key test of biodiversity theory has been how well ecological models reproduce empirical distributions of species abundances. However, ecological models with very different assumptions can predict similar species abundance distributions, whereas models with similar assumptions may generate very different predictions. This complicates inferring processes driving community structure from model fits to data. Here, we use an approximation that captures common features of "neutral" biodiversity models-which assume ecological equivalence of species-to test whether neutrality is consistent with patterns of commonness and rarity in the marine biosphere. We do this by analyzing 1,185 species abundance distributions from 14 marine ecosystems ranging from intertidal habitats to abyssal depths, and from the tropics to polar regions. Neutrality performs substantially worse than a classical nonneutral alternative: empirical data consistently show greater heterogeneity of species abundances than expected under neutrality. Poor performance of neutral theory is driven by its consistent inability to capture the dominance of the communities' most-abundant species. Previous tests showing poor performance of a neutral model for a particular system often have been followed by controversy about whether an alternative formulation of neutral theory could explain the data after all. However, our approach focuses on common features of neutral models, revealing discrepancies with a broad range of empirical abundance distributions. These findings highlight the need for biodiversity theory in which ecological differences among species, such as niche differences and demographic trade-offs, play a central role.etermining how biodiversity is maintained in ecological communities is a long-standing ecological problem. In species-poor communities, niche and demographic differences between species can often be estimated directly and used to infer the importance of alternative mechanisms of species coexistence (1-3). However, the "curse of dimensionality" prevents the application of such species-by-species approaches to high-diversity assemblages: the number of parameters in community dynamics models increases more rapidly than the amount of data, as species richness increases. Moreover, most species in high-diversity assemblages are very rare, further complicating the estimation of strengths of ecological interactions among species, or covariation in different species' responses to environmental fluctuations. Consequently, ecologists have focused instead on making assumptions about the overall distribution of demographic rates, niche sizes, or other characteristics of an assemblage, and then deriving the aggregate assemblage properties implied by those assumptions (4-8). One of the most commonly investigated of these assemblage-level properties is the species abundance distribution (SAD)-the pattern of commonness and rarity among ...

Since 1998 the non-indigenous Pacific oyster Crassostrea gigas (Thunberg 1793) has been invading the Wadden Sea of Lower Saxony, southern German Bight. C. gigas settles predominantly on intertidal Mytilus-beds (M. edulis L.) and subsequently create rigid reef-like structures. Both bivalve species are ecosystem engineers in sedimentary tidal flats. They provide hard substrate for sessile species, mobile organisms find refuge within the habitat matrix of dense suspension feeders, and biodeposits enrich the sediments with organic matter. The transformation of Mytilus-beds into Crassostrea-reefs gives rise to the question whether the invader may affect the native community. We investigated two parts of a changing bivalve bed in the backbarrier area of the island of Juist in March 2005. One part was still dominated by M. edulis whereas the other part was already densely colonized by C. gigas. Crassostrea-reefs compensate for the conceivable loss of Mytilus-beds in the intertidal of the Wadden Sea by replacing the ecological function of M. edulis. There was no indication of a suppression of indigenous species. This even applied to M. edulis, which persisted at the site invaded by C. gigas. The associated macrofaunal community showed increased species richness, abundance, biomass, and diversity in the Crassostrea-reef. The latter particularly favored sessile species like anthozoans, hydrozoans, and barnacles. Higher abundance and biomass for vagile epizoic species like the shore crab Carcinus maenas and the periwinkle Littorina littorea also occurred among oysters. Abundance of deposit feeding oligochaetes was enhanced by oysters as well. More opportunistic, facultative filter-feeding polychaetes occurred in the Crassostrea-reef.

This series represents a secondary level of scientifiic publishing. All issues employ thorough internal scientific review; some issues employ external scientific review. Reviews are --by design --transparent collegial reviews, not anonymous peer reviews. All issues may be cited in formal scientific communications. NOAA Technical Memorandum NMFS-NE-148Editorial Notes on Issues 122-152 in the NOAA Technical Memorandum NMFS-NE Series Editorial ProductionFor Issues 122-152, staff of the Northeast Fisheries Science Center's (NEFSC's) Ecosystems Processes Division have largely assumed the role of staff of the NEFSC's Editorial Office for technical and copy editing, type composition, and page layout. Other than the four covers (inside and outside, front and back) and first two preliminary pages, all preprinting editorial production has been performed by, and all credit for such production rightfully belongs to, the authors and acknowledgees of each issue, as well as those noted below in "Special Acknowledgments." Special AcknowledgmentsDavid B. Packer, Sara J. Griesbach, and Luca M. Cargnelli coordinated virtually all aspects of the preprinting editorial production, as well as performed virtually all technical and copy editing, type composition, and page layout, of Issues 122-152. Rande R. Cross, Claire L. Steimle, and Judy D. Berrien conducted the literature searching, citation checking, and bibliographic styling for Issues 122-152. Joseph J. Vitaliano produced all of the food habits figures in Issues 122-152. Internet AvailabilityIssues 122-152 are being copublished, i.e., both as paper copies and as web postings. All web postings are, or will soon be, available at: www.nefsc.nmfs.gov/nefsc/habitat/efh. Also, all web postings will be in "PDF" format. Information UpdatingBy federal regulation, all information specific to Issues 122-152 must be updated at least every five years. All official updates will appear in the web postings. Paper copies will be reissued only when and if new information associated with Issues 122-152 is significant enough to warrant a reprinting of a given issue. All updated and/or reprinted issues will retain the original issue number, but bear a "Revised (Month Year)" label. Species NamesThe NMFS Northeast Regions policy on the use of species names in all technical communications is generally to follow the American Fisheries Societys lists of scientific and common names for fishes (i.e., Robins et al. 1991 a ), mollusks (i.e., Turgeon et al. 1998 b ), and decapod crustaceans (i.e., Williams et al. 1989 c ), and to follow the Society for Marine Mammalogy's guidance on scientific and common names for marine mammals (i.e., Rice 1998

Existing reconstructions of the winter North Atlantic Oscillation (WNAO) are based on terrestrial proxies and historical documents. No direct high-resolution, long-term records from marine settings are available for this major climate-dictating phenomenon, which severely affects a variety of economic aspects of our society. Here we present a 245 yr proxy WNAO index based on shells of the long-lived marine bivalve mollusk Arctica islandica. Variations in annual rates of shell growth are positively correlated with WNAO-related changes in the food supply. Maximum amplitudes in frequency bands of 7-9 and 5-7 yr fall exactly within the range of instrumental and other proxy WNAO indices. These estimates were obtained for specimens collected live, 2000 km apart, in the central North Sea and on the Norwegian Shelf. Hence, the WNAO influences hydrographic regimes of large regions of the ocean. Our study demonstrates that A. islandica can reliably reconstruct WNAO dynamics for time intervals and regions without instrumental records. Our new tool functions as a proxy for the WNAO index prior to the twentieth-century greenhouse forcing and has the potential to further validate other proxy-based WNAO records.