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Whereas the anthropogenic impact on marine biodiversity is undebated, the quantification and prediction of this change are not trivial. Simple traditional measures of biodiversity (e.g. richness, diversity indices) do not capture the magnitude and direction of changes in species or functional composition. In this paper, we apply recently developed methods for measuring biodiversity turnover to time-series data of four broad taxonomic groups from two coastal regions: the southern North Sea (Germany) and the South African coast. Both areas share geomorphological features and ecosystem types, allowing for a critical assessment of the most informative metrics of biodiversity change across organism groups. We found little evidence for directional trends in univariate metrics of diversity for either the effective number of taxa or the amount of richness change. However, turnover in composition was high (on average nearly 30% of identities when addressing presence or absence of species) and even higher when taking the relative dominance of species into account. This turnover accumulated over time at similar rates across regions and organism groups. We conclude that biodiversity metrics responsive to turnover provide a more accurate reflection of community change relative to conventional metrics (absolute richness or relative abundance) and are spatially broadly applicable. This article is part of the theme issue 'Integrative research perspectives on marine conservation'.

the 7th conference of the parties to the Convention on Biological Diversity (CBD-COP7, Kuala Lumpur, 2004) it was agreed to establish a global network of marine and coastal protected areas by 2012. The defined objectives of this MPA-network are based on the ecosystem approach: to protect biodiversity and other ecological values, and to ensure sustainable use. The (inter)national policy guidelines state that the selection of MPAs should be based on scientific information and ecological criteria only. As a signatory to the Convention, the Netherlands is now faced with meeting this obligation, and the process of designating the first Marine Protected Areas (MPAs) in the Dutch part of the North Sea is currently in progress. We focus on the science-policy interactions that are part of this Dutch MPA selection process. By taking a closer look at the contemporary site selection process as well as its historical background, we show that ecological, socio-economic and political considerations cannot always be easily separated. Uncertainty is high and the ultimate selection and delimitation of candidate sites rather seems to be the result of a balancing act between ecological, socio-economic and political interests, in which scientific and policy guiding procedures blend with ad-hoc political decision making, and with expert judgment in cases where data is lacking. As such, this paper presents an example of present-day environmental policy making in action. [ABSTRACT FROM AUTHOR]

Johnson, D. 2008. Environmental indicators: their utility in meeting the OSPAR Convention's regulatory needs. – ICES Journal of Marine Science, 65: 1387–1391.The role of marine environmental indicators is clear; selecting indicators to inform management and for the development of accepted frameworks is proving more elusive. The OSPAR Commission, charged with the environmental protection of the Northeast Atlantic, has been applying an ecosystem approach since 1998, applying on a trial basis a system of ecological quality objectives as indicators of ecosystem health for the North Sea. This paper presents a framework for biodiversity monitoring and assessment, and discusses specific issues associated with marine-litter indicators, representing a cell within the matrix of the framework. In the immediate future, European marine legislation will drive the development of environmental indicators in the area, and further harmonization of indicator sets should enhance their utility. [ABSTRACT FROM PUBLISHER]

Species commonness is often related to abundance and species conservation status. Intuitively, a “common species” is a species that is abundant in a certain area, widespread and at low risk of extinction. Analysing and classifying species commonness can help discovering indicators of ecosystem status and can prevent sudden changes in biodiversity. However, it is challenging to quantitatively define this concept. This paper presents a procedure to automatically characterize species commonness from biological surveys. Our approach uses clustering analysis techniques and is based on a number of numerical parameters extracted from an authoritative source of biodiversity data, i.e. the Ocean Biogeographic Information System. The analysis takes into account abundance, geographical and temporal aspects of species distributions. We apply our model to North Sea fish species and show that the classification agrees with independent expert opinion although sampling biases affect the data. Furthermore, we show that our approach is robust to noise in the data and is promising in classifying new species. Our method can be used in conservation biology, especially to reduce the effects of the sampling biases which affect large biodiversity collections. [ABSTRACT FROM AUTHOR]

Although the identification of organisms to the level of species is the ideal in studies of marine macrobenthos, there are situations where such a fine level of taxonomic discrimination may be either impossible or unwarranted, for example when much the fauna is undescribed, or if the task for which samples are collected does not require them to be identified to the species level. The idea that abundances of higher taxa, or particular groups of organisms, may be used as surrogates for the total fauna in such studies is explored in this paper using data from the Norwegian sector of the North Sea. The general conclusion is that, in surveys of soft sediment macrofauna in disturbed areas of the North Sea where pollution imposes simple spatial gradients on the benthic communities, little information about inter-sample relationships is lost using data based on family, polychaete species, orpolychaete family abundances, rather than species abundances. In more pristine areas where spatial patterns are determined by a number ofprocesses, correlations between calculated diversity indices and similarity in faunal patterns between species and family abundances are still very high, but less so for polychaete species or polychaete family abundances. This suggests that identification to the level of family may be satisfactory in many routine monitoring surveys,and identification of only the polychaetes, either to the level of species or family, may also be a possible alternative if there are clear disturbance gradients in the survey area. Polychaetes are of importance in disturbed areas because the group contains tolerant and intolerant species, and in undisturbed areas because within the taxon species have agreater range of trophic and reproductive strategies than within other taxa. Ultimately it is the distribution of species, their identities, and their interactions with each other and with the environment, that are of interest. The use of surrogates is likely to be most advanta [ABSTRACT FROM AUTHOR]

We combined sediment and faunal data to explore the role of the sedimentary regime in shaping the distribution of subtidal sandbank environments and the associated meiofaunal nematode communities at Broken Bank and Swarte Bank, in the southern North Sea. A variety of sediment transport processes occur in the area, differing in the frequency and magnitude of sediment mobility, and the continuum between erosion, translation and sediment accumulation. The seabed contained a variety of bedforms, including longitudinal furrows, and small to very large sandwaves. The bed sediments were dominated by fine and medium sands, with admixtures of silt and gravel. Based on sedimentary bedforms and grain size analysis, a total of 11 sedimentary facies were delineated, of which 8 were analysed in detail for their relationships with the meiofauna. The sedimentary facies fell clearly into groups of facies, respectively representing high, high-moderate and moderate, and episodic sediment mobility. For those sedimentary facies where daily movement of sediments and bedforms occurred (‘high’ sediment mobility), the resulting spatially homogeneous environments were dominated by an impoverished nematode community comprising small deposit feeders and large predators. Resistance to sediment movement and the ability to exploit alternative food sources were prominent functional features of the successful colonisers. Those facies characterised by relatively infrequent sediment mobility (‘episodic’ and ‘high-moderate and moderate’ sediment mobility) comprised a heterogeneous suite of benthic habitats, containing taxonomically and functionally diverse assemblages of nematodes of various sizes, feeding types and reproductive potential. Faunal distribution patterns here indicated trade-offs between the resistance to sediment movement, environmental tolerance and competitive abilities. Our focus on diverse assemblages of organisms with high turnover times, inhabiting highly dynamic sedimentary environments, has revealed new animal-sediment relationships of relevance to pure and applied science. [ABSTRACT FROM AUTHOR]

Marine environmental management policies seek to ensure that fishing impacts on fished populations and other components of the ecosystem are sustainable, to simultaneously meet objectives for fisheries and conservation. For example, in Europe, targets for (i) biodiversity, (ii) food web structure as indicated by the proportion of large fish and (iii) fishing mortality rates for exploited species that lead to maximum sustainable yield, FMSY, are being proposed to support implementation of the Marine Strategy Framework Directive. Efforts to reconcile any trade-offs among objectives need to be informed by knowledge on the consequences of alternate management actions., We develop, calibrate and apply a multispecies size spectrum model of the North Sea fish community to assess the response of populations and the community to fishing. The model predicts species' size distributions, abundance, productivity and interactions and therefore provides a single framework for evaluating trade-offs between population status, community and food web structure, biodiversity and fisheries yield., We show that the model can replicate realistic fish population and community structure and past responses to fishing. We assess whether meeting management targets for exploited North Sea populations (fishing species at FMSY) will be sufficient to meet proposed targets for biodiversity and food web indicators under two management scenarios (status quo and FMSY)., The recovery in biodiversity indicators is 60% greater when fishing populations at FMSY than if status quo (2010) fishing rates are maintained. The probability of achieving a food web target was 60% under both scenarios in spite of major community restructuring revealed by other indicators of community size structure., Synthesis and applications. Our model can be applied to evaluate indicator targets and trade-offs among fisheries and conservation objectives. There is a significant probability that reductions in fishing mortality below FMSY would be needed in Europe if managers make a binding commitment to a proposed large fish indicator target, with concomitant reductions in fisheries yield. [ABSTRACT FROM AUTHOR]

Coastal marine systems are currently subject to a variety of anthropogenic and climate-change-induced pressures. An important challenge is to predict how marine sediment communities and benthic biogeochemical cycling will be affected by these ongoing changes. To this end, it is of paramount importance to first better understand the natural variability in coastal benthic biogeochemical cycling and how this is influenced by local environmental conditions and faunal biodiversity. Here, we studied sedimentary biogeochemical cycling at ten coastal stations in the Southern North Sea on a monthly basis from February to October 2011. We explored the spatio-temporal variability in oxygen consumption, dissolved inorganic nitrogen and alkalinity fluxes, and estimated rates of nitrification and denitrification from a mass budget. In a next step, we statistically modeled their relation with environmental variables and structural and functional macrobenthic community characteristics. Our results show that the cohesive, muddy sediments were poor in functional macrobenthic diversity and displayed intermediate oxygen consumption rates, but the highest ammonium effluxes. These muddy sites also showed an elevated alkalinity release from the sediment, which can be explained by the elevated rate of anaerobic processes taking place. Fine sandy sediments were rich in functional macrobenthic diversity and had the maximum oxygen consumption and estimated denitrification rates. Permeable sediments were also poor in macrobenthic functional diversity and showed the lowest oxygen consumption rates and only small fluxes of ammonium and alkalinity. Macrobenthic functional biodiversity as estimated from bioturbation potential appeared a better variable than macrobenthic density in explaining oxygen consumption, ammonium and alkalinity fluxes, and estimated denitrification. However, this importance of functional biodiversity was manifested particularly in fine sandy sediments, to a lesser account in permeable sediments, but not in muddy sediments. The strong relationship between macrobenthic functional biodiversity and biogeochemical cycling in fine sandy sediments implies that a future loss of macrobenthic functional diversity will have important repercussions for benthic ecosystem functioning. [ABSTRACT FROM AUTHOR]

Rice, J., Daan, N., Gislason, H., and Pope, J. Does functional redundancy stabilize fish communities? – ICES Journal of Marine Science, 70: 734–742.Functional redundancy of species sharing a feeding strategy and/or maximum size has been hypothesized to contribute to increased resilience of marine fish communities (the “portfolio effect”). A consistent time-series of survey data of fish in the North Sea was used to examine if trophic functional groups or maximum length of species (Lmax) groups with larger numbers of species had lower coefficients of variation in abundance and biomass over time than did groupings with fewer species. Results supported this hypothesis. However, the stabilizing effect of numbers of species in a group on variation in abundance or biomass could be accounted for by the Law of Large Numbers, providing no evidence that specific ecological processes or co-adaptations are necessary to produce this effect. This implies that successful conservation policies to maintain the resilience of a marine fish community could be based on strategies to maintain the number of species in functional groups, without having to know the detailed ecological interactions between the species. [ABSTRACT FROM PUBLISHER]

The North Sea coast of the Dutch barrier island of Schiermonnikoog is covered by microbial mats that initiate a succession of plant communities that eventually results in the development of a densely vegetated salt marsh. The North Sea beach has a natural elevation running from the low water mark to the dunes resulting in gradients of environmental factors perpendicular to the beach. These gradients are due to the input of seawater at the low water mark and of freshwater from upwelling groundwater at the dunes and rainfall. The result is a natural and dynamic salinity gradient depending on the tide, rainfall and wind. We studied the microbial community composition in thirty three samples taken every ten meters along this natural salinity gradient by using denaturing gradient gel electrophoresis (DGGE) of rRNA gene fragments. We looked at representatives from each Domain of life (Bacteria, Archaea and Eukarya) and with a particular emphasis on Cyanobacteria. Analysis of the DGGE fingerprints together with pigment composition revealed three distinct microbial mat communities, a marine community dominated by diatoms as primary producers, an intermediate brackish community dominated by Cyanobacteria as primary producers and a freshwater community with Cyanobacteria and freshwater green algae. [ABSTRACT FROM AUTHOR]

The ecosystem approach to management requires the status of individual species to be considered in a community context. We conducted a comparative ecosystem analysis of the Georges Bank and North Sea fish communities to determine the extent to which biological diversity is restored when fishing pressure is reduced. First, fishing mortality estimates were combined to quantify the community‐level intensity and selectivity of fishing pressure. Second, standardized bottom‐trawl survey data were used to investigate the temporal trends in community metrics. Third, a size‐based, multispecies model (LeMans) was simulated to test the response of community metrics to both hypothetical and observed changes in fishing pressure in the two communities. These temperate North Atlantic fish communities have much in common, including a history of overfishing. In recent decades fishing pressure has been reduced, and some species have started to rebuild. The Georges Bank fishery has been more selective, and fishing pressure was reduced sooner. The two communities have similar levels of size diversity and biomass per unit area, but fundamentally different community structure. The North Sea is dominated by smaller species and has lower evenness than Georges Bank. These fundamental differences in community structure are not explained by recent fishing patterns. The multispecies model was able to predict the observed changes in community metrics better on Georges Bank, where rebuilding is more apparent than in the North Sea. Model simulations predicted hysteresis in rebuilding community metrics toward their unfished levels, particularly in the North Sea. Species in the community rebuild at different rates, with smaller prey species outpacing their large predators and overshooting their pre‐exploitation abundances. This indirect effect of predator release delays the rebuilding of community structure and biodiversity. Therefore community rebuilding is not just the sum of single‐species rebuilding plans. Management strategies that account for interspecific interactions will be needed to restore biodiversity and community structure. [ABSTRACT FROM AUTHOR]

The article reports that the areas along the western Europe margin encompass a vast geographical area, which comprises of habitats, and a home for more than 10,000 metazoan species. It states that a major challenge in the ecosystem research is to identify the casual link between biodiversity and ecosystem functioning. It mentions that one of the most conspicuous and important factors influencing marine ecosystems in the North Atlantic and the Arctic is the Gulf Stream System (GSS). It presents that an interest in large-scale patterns of benthic communities and their biodiversity was stimulated around 1986 by the growing recognition of intensive bottom- and beam-trawl fisheries in the North Sea, which were posing a threat to benthic communities, biodiversity, and habitat.

Greenstreet, S. P. R. 2008. Biodiversity of North Sea fish: why do the politicians care but marine scientists appear oblivious to this issue? – ICES Journal of Marine Science, 65: 1515–1519.Political drivers underpinning the development of an Ecosystem Approach to Marine Management (EAMM) focus on conserving and restoring biodiversity. However, the Element of Ecological Quality for Fish Communities that emerged from the 2002 Bergen North Sea Ministerial Conference relates to “Changes in the proportion of large fish and hence the average weight and average maximum length of the fish community”. How did this apparent change in direction arise? Responding to advice requests from OSPAR, ICES established seven criteria for identifying “state” indicators capable of supporting indicator-based management. Application of these criteria underlined the merits of indicators of fish size, whereas diversity indices performed poorly against four of the criteria. These difficulties are examined here. Far from being oblivious to the issue of biodiversity, marine scientists recognized that they were not in a position to recommend Ecological Quality Objectives (EcoQOs) for fish biodiversity that would have relied on the use of biodiversity indicators. The use of indicators of size structure, for which the theoretical foundation was better developed, allowed the continued development of an EAMM in the short term. However, if the issue of biodiversity is to be addressed in the longer term, then shortcomings associated with the use of biodiversity indicators need to be addressed. [ABSTRACT FROM PUBLISHER]

Tett, P., Carreira, C., Mills, D. K., van Leeuwen, S., Foden, J., Bresnan, E., and Gowen, R. J. 2008. Use of a Phytoplankton Community Index to assess the health of coastal waters. – ICES Journal of Marine Science, 65: 1475–1482.Monitoring of marine-ecosystem status and health requires indicators of community structure and function. As a structural indicator, we propose a Phytoplankton Community Index (PCI) based on the abundance of “life-forms” such as “pelagic diatoms” or “medium-sized autotrophic dinoflagellates”. To calculate the PCI, data showing seasonal variation in these abundances are plotted in “life-form space” of two or more dimensions. Data from a “type-specific reference condition” are then enclosed within a reference envelope. Comparison data are plotted into the same coordinate system, and the PCI is the proportion (between 0 and 1) of these new data that fall within the reference envelope. Results from initial applications of this method are shown for UK coastal waters in the northern North Sea (near Stonehaven), a Scottish fjord (Loch Creran), and the eastern Irish Sea (including Liverpool Bay). The Stonehaven data (1997–2005) were used to compare values obtained from weekly sampling with those from monthly sampling. A spatial comparison between more- and less-nutrient-enriched waters in the eastern Irish Sea (1991–2003) showed little difference in phytoplankton community structure. Loch Creran has experienced a large change in the “balance of organisms”, and hence a reduction in the PCI, between 1979–1981 and 2006/2007, associated with a decrease in chlorophyll but no apparent change in nutrients. These results are discussed in relation to the intended uses of the PCI as an index of biological quality for the Water Framework Directive (WFD) and an index of ecosystem health in the context of eutrophication. Although the method only measures change, it can also be used as an indicator of biological quality if the reference conditions are those defined for a WFD waterbody, and as an indicator of health if appropriately calibrated. Suggestions are made for further development. [ABSTRACT FROM PUBLISHER]

Climate change has been predicted to lead to changes in local and regional species richness through species extinctions and latitudinal ranges shifts. Here, we show that species richness of fish in the North Sea, a group of ecological and socio-economical importance, has increased over a 22-year period and that this rise is related to higher water temperatures. Over eight times more fish species displayed increased distribution ranges in the North Sea (mainly small-sized species of southerly origin) compared with those whose range decreased (primarily large and northerly species). This increase in species richness can be explained from the fact that fish species richness in general decreases with latitude. This observation confirms that the interaction between large-scale biogeographical patterns and climate change may lead to increasing species richness at temperate latitudes. [ABSTRACT FROM AUTHOR]

Food choice, feeding habitat use and spatial distribution of black-headed gulls (Larus ridibundus), mew gulls (L. canus), herring gulls (L. argentatus) and lesser black-backed gulls (L. fuscus) were studied in the south-eastern North Sea. At-sea distribution during the breeding period was assessed by transect counts from ships. Clear differences could be established between the four species, with lesser black-backed gulls being widespread and numerous far out at sea and mew and black-headed gulls being restricted to the coastal area; herring gulls showed an intermediate pattern. The diet of these sympatrically breeding gulls was analysed from pellet and faecal samples collected at two colonies. Considering biases in this method, the following components appeared to comprise the principal food for each species: black-headed gulls: bivalves, crustaceans; mew gulls: bivalves, polychaetes; herring gulls: bivalves, crustaceans; and lesser black-backed gulls: fish and crustaceans. Black-headed and mew gulls had much broader dietary niches than herring and lesser black-backed gulls. Based on spatial distribution, food choice and feeding habitat use, three types of foraging strategies are apparent: (1) black-headed and mew gulls forage both intertidally and on land, (2) herring gulls feed most frequently in the intertidal zone and (3) lesser black-backed gulls feed at sea. The foraging behaviour of these four species may well have influenced their current population trends in the study area. [ABSTRACT FROM AUTHOR]

There is a worldwide concern about the expansion of non-indigenous species because they may threaten local biodiversity as some of them may successfully outcompete native species. We report on the presence of two introduced mud worm species, Boccardia proboscidea and Boccardiella hamata, in the southern North Sea, where the former species has been discovered on groynes along the Belgian coast and both species were detected among Pacific oysters Crassostrea gigas in the south-western Dutch delta. Boccardia proboscidea is native to the North Pacific and was first detected in Europe along the Spanish Basque coast in 1996. Our record is the third for European waters and the first for the North Sea. Although B. proboscidea occurs in limited numbers and in ephemeral habitats along the Belgian coast, the species probably has established a permanent population, since it has been reported repeatedly after its first discovery in January 2011. Boccardiella hamata is native to the Atlantic and Gulf coasts of North America. This species has never been recorded from Europe before.Our research demonstrates that in under-studied habitats, such as man-made hard substrata, even well-established populations of newly introduced species may stay undetected. Due to a lack of monitoring of these particular habitats and insufficient knowledge about introduced biota, introduced species may pass unnoticed or may be overlooked for several years. A dedicated monitoring will be necessary to detect introduced species in an early stage. In view of the upcoming Marine Strategy Framework Directive requirements such monitoring will be inevitable. [ABSTRACT FROM PUBLISHER]