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This datasheet on Ensis directus covers Identity, Overview, Distribution, Dispersal, Biology & Ecology, Environmental Requirements, Natural Enemies, Impacts, Prevention/Control, Further Information.

In het kader van het Mosselconvenant zijn afspraken gemaakt over de optimalisatie van de kweekpercelen in de westelijke Waddenzee. Dit houdt in dat er nieuwe kweekpercelen voor mosselen uitgegeven worden op locaties waarvan men verwacht dat goede rendementen gerealiseerd kunnen worden en er op andere locaties percelen, waar laag rendement gehaald wordt, worden opgegeven. Dit resulteert in de aanleg van 840 ha nieuw kweekareaal waar momenteel geen schelpdierbanken aanwezig zijn. Als gevolg van het introduceren van hard substraat (in de vorm van kweekpercelen) kunnen er mogelijk verschuivingen optreden in de bodemdiergemeenschap en andere aan de mossel geassocieerde soorten. Gezien de schaalgrootte van de maatregel is het relevant om hiernaar onderzoek te doen. In 2018 en 2019 zijn T0 bodemmonsters genomen om daaruit de bodemdiergemeenschappen voor aanleg van nieuwe percelen in kaart te brengen. Dit is van belang om in de toekomst vast te kunnen stellen of er mogelijk een verandering in de bodemdiergemeenschap opgetreden is door aanleg van percelen. De voorliggende technische rapportage beschrijft de methode en de voorlopige resultaten van de T0 bemonstering. Nadere analyse en discussie zullen plaatsvinden wanneer de bemonsteringen uitgevoerd zijn nadat percelen in gebruik genomen zijn. In Juni 2018 zijn er negen perceellocaties bemonsterd: Oosterom, Kabelgat, Wolfshoek (noord en zuid) en Gat van Pietje in de Vliestroom komberging, en Westkom (west en oost), Scheer en Texel in de Marsdiep komberging. In totaal betrof dit 356 ha van het areaal aan geplande nieuwe percelen. In Juni 2019 zijn de locaties Texel, Westkom oost en Gat van Pietje komen te vervallen. De bodemmonsters zijn genomen met een Boxcorer. De monsters zijn vervolgens gespoeld over een zeef van 1.0 mm en ten slotte gepreserveerd met formaline. In totaal zijn er respectievelijk 163 en 174 bodemmonsters verzameld in 2018 en 2019. Alleen de monsters uit 2018 zijn gedetermineerd en worden beschreven in de huidige rapportage. Hierbij zijn de drie locaties die zijn komen te vervallen ook nog niet geanalyseerd. In totaal resulteerde dat in 109 monsters verdeeld over zes locaties. Het aantal monsterpunten per locatie varieerde van 14 tot 21. Tijdens de T0 bemonstering in 2018 zijn er in totaal 136 soorten aangetroffen. De hoogste dichtheden (80766 indiv m-2) en biomassa (1478 g m-2) aan soorten wordt waargenomen op locatie Kabelgat. De soortensamenstelling wordt hier echter slechts door een beperkt aantal soorten (n=49) gedomineerd in vergelijking met de andere locaties. De laagste dichtheden (5703 indiv m-2) en biomassa (337 g m-2) van de bodemdiergemeenschap was waargenomen op het Oosterom, waar daarentegen de soortenrijkdom met 83 soorten hoog was. Het meeste aantal soorten (n=85) zijn waargenomen op locatie Scheer, en het meeste aantal soorten per monsterpunt was het hoogste in de Westkom. De bodemiergemeenschap op de locaties in het Marsdiep kombergingsgebied (Scheer, Westkom) konden op basis van indirecte gradiëntanalyse (DCA en RDA) duidelijk onderscheiden worden van de locaties in de Vliestroom komberging (Oosterom, Kabelgat, Wolfshoek). De soortensamenstelling op alle locaties werd gedomineerd door Annelida (wormen) en Mollusca (weekdieren). Op vrijwel alle locaties waren Ensis leei (mesheften) en/of Marenzelleria viridis (gewone groenworm) dominant. Deze soorten zijn beide exoten in de Waddenzee. In totaal zijn er in deze studie negen exoten aangetroffen, welke allen reeds bekend zijn voor de Waddenzee en Nederlandse kustwateren. Er zijn ook zeven typische H1110 soorten aangetroffen, welke slechts in beperkte mate de dichtheden en soorten aantallen op de locaties vertegenwoordigden.

For the cultivation of mussels, wild stocks of juveniles are harvested to collect mussel seed as starting material for the culture. These wild stocks are found in the sublittoral western Wadden Sea (NL). After summer spat fall, fisheries in Autumn on newly formed beds is carried out in areas that have the risk of washing away due to storms, or are vulnerable for starfish predation. These wild beds are considered as relatively unstable. On remaining more stable wild beds, seed fishery is carried out in next Spring. As the Wadden Sea is a nature conservation area, mussel seed fisheries is only allowed if no negative impacts on the nature management objectives can be expected. Seed fishery impacts were addressed in an extensive study including effects on sediment composition, macrobenthos and epifauna. In this paper we describe the effects of mussel seed fisheries on the development of the mussel stocks with and without fisheries in 39 pairwise studied impact and control plots. Stocks on seed beds in areas of the sublittoral Western Wadden Sea that are known as unstable, show a large decline within one year after settlement, also when there is no seed fishery. Harvesting seed on more stable beds in Spring results in a statistical significant reduction in stock size, which lasts for a period of two years after the first fishery. For the longer term, there is a gradual decline of the mussel stocks on all studied plots. On three out of the 39 plots, mussel biomass showed a large increase, both on control and impact parts. Also these mussel beds declined and eventually disappeared. A difference in life expectancy of fished and unfished beds was not demonstrated. It is concluded that sublittoral beds gradually disappear, also without fisheries. As a consequence, new recruitment is of critical importance for the long-term survival of sublittoral mussel beds. As we found no significant difference between recruitment on fished and control parts, there are no indications for negative impacts of seed fishery on new recruitment.

There is concern across the International Council for the Exploration of the Sea (ICES) region that a consideration of vulnerable components and the wider support mechanisms underpinning benthic marine ecosystems may be lacking from the process of marine protected area (MPA) designation, management and monitoring. In this study, MPAs across six European ecoregions were assessed from a benthic ecology perspective. The study included 102 MPAs, designated by 10 countries, and focused on three aspects regarding the role of the benthos in: (i) the designation of MPAs; (ii) the management measures used in MPAs; and (iii) the monitoring and assessment of MPAs. Qualitative entries to a questionnaire based on an existing framework (EU project ‘Monitoring Evaluation of Spatially Managed Areas’, (MESMA) were collected by 19 benthic experts of the ICES Benthic Ecology Working Group. A pedigree matrix was used to apply a numerical scale (score) to these entries. The results showed clear differences in scores between ecoregions and between criteria. The designation‐phase criteria generally achieved higher scores than the implementation‐phase criteria. Poor designation‐phase scores were generally reiterated in the implementation‐phase scores, such as scores for assessment and monitoring. Over 70% of the MPA case studies were found to consider the benthos to some extent during selection and designation; however, this was not followed up with appropriate management measures and good practice during the implementation phase. Poor spatial and temporal coverage of monitoring and ineffective indicators is unlikely to pick up changes caused by management measures in the MPA. There is concern that without adequate monitoring and adaptive management frameworks, the MPAs will be compromised. Also, there could be an increased likelihood that, with regard to the benthos, they will fail to meet their conservation objectives. This assessment was successful in highlighting issues related to the representation and protection of the benthos in MPAs and where changes need to be made, such as expanding the characterization and monitoring of benthic species or habitats of interest. These issues could be attributable to an ongoing process and/or an indication that some MPAs only have ‘paper protection’.

In 2006 is een planologische kernbeslissing genomen over het Project Mainportontwikkeling Rotterdam (PMR). In dit kader is in 2008 begonnen met de aanleg van Maasvlakte 2. In samenhang daarmee zijn natuurcompensatiemaatregelen genomen in de Voordelta. Vanaf 2009 is in het kader van het project Natuurcompensatie Voordelta (PMR-NCV) een monitoring- en onderzoeksprogramma uitgevoerd in de Voordelta, voortvloeiend uit de monitoringverplichtingen in het kader van de vergunning op grond van de Nb-wet 1998 voor de aanleg en aanwezigheid van Maasvlakte 2 en de bijbehorende natuurcompensatie. Het hier voorliggende rapport vormt de wetenschappelijke rapportage over de resultaten van het programma. Het rapport geeft een synthese van de monitorings- en onderzoeksresultaten uit de nulmetingen (2004-2007) en de eerste (2009-2015) en tweede (2016-2018) fase van PMR-NCV, aangevuld met de resultaten van ander relevant onderzoek. Op grond hiervan worden de effecten van de natuurcompensatiemaatregelen beschreven. Dit rapport vormt een vervolg op de in 2018 gepubliceerde synthese (Tulp et al., 2018a). Het rapport omvat zowel een actualisatie van analyseresultaten en conclusies op basis van meetgegevens uit recente jaren die nog niet beschikbaar waren in 2018, als resultaten van nieuwe analyses.

Met de aanleg van Maasvlakte 2 is de haven van Rotterdam uitgebreid. Maasvlakte 2 ligt in de Voordelta, een Natura 2000-gebied. In de Passende Beoordeling die in 2007 is uitgevoerd, is een aantal effecten van de aanwezigheid van Maasvlakte als significant negatief beoordeeld. Ter compensatie van deze effecten is binnen de Voordelta een aantal maatregelen getroffen, onder meer een bodembeschermingsgebied. In het bodembeschermingsgebied worden beperkingen opgelegd aan vormen van visserij die de zeebodem beroeren. De boomkorvisserij met wekkerkettingen door schepen met een motorvermogen groter dan 260 pk (191 kW) (Eurokotters) is niet toegestaan. Om het effect van de instelling van het bodembeschermingsgebied te kunnen evalueren, zijn in de periode 2004-2007 metingen verricht om de nulsituatie vast te leggen, en is vanaf 2009 het monitoringsprogramma voor de natuurcompensatie gestart. De resultaten van de eerste fase (2009-2013) m.b.t. de monitoring van de bodemdieren zijn gerapporteerd in Craeymeersch et al. (2015). De opzet van de monitoring had als primair doel een vergelijking van de ontwikkelingen vóór en na de instelling van het bodembeschermingsgebied. Het verschil in verandering tussen het bodembeschermingsgebied en de referentiegebieden zou inzicht geven in het effect van de compensatiemaatregelen. Omdat de boomkorvisserij ook in de referentiegebieden sterk afgenomen is, ontbreekt enig contrast tussen de referentiegebieden en bodembeschermingsgebied, is er geen duidelijk behandelingseffect, en is aan de voorwaarde voor een goede BACI-opzet niet voldaan. Omdat de BACI opzet niet heeft gewerkt, zijn een aantal aanvullende analyses uitgevoerd naar de relatie tussen trends in bodemdieren en trends in visserij (Craeymeersch et al., 2015). Zo is ondermeer gekeken naar de correlatieve verbanden tussen een aantal benthische indicatoren en visserij-intensiteit, maar deze bleken niet eenduidig. Evenmin leken trends in de dichtheid van een aantal soorten gevoelig voor bodemberoering gerelateerd aan veranderingen (afnames) in visserij-intensiteit, misschien op de populatie van Chamelea striatula na. De tweede fase van het onderzoek startte in 2016. In de tussenliggende jaren is het lopende onderzoek gedeeltelijk voortgezet. Zo is in 2015 het benthos weer bemonsterd, zij het in een aangepaste opzet (238 i.p.v. 411 stations). Vanaf 2016 is dezelfde opzet als in 2015 gevolgd. Het voorliggende rapport beschrijft de opzet van de monitoring, alsook de eerste monitoring-resultaten in de periode 2016-2018 d.m.v. een korte beschrijving van de dataset.

This paper reports the first records of the dwarf surf clam Mulinia lateralis (Say, 1822) outside its native area, which is the western Atlantic Ocean, ranging from the Gulf of St Lawrence to the Gulf of Mexico. In 2017 and 2018 specimens were found in the Dutch coastal waters (North Sea), in the Wadden Sea and in the Westerschelde estuary, in densities of up to almost 6000 individuals per square meter. In view of its ecology and distributional range in the native area M. lateralis has the potential to become an invasive species. Its ability to quickly colonize defaunated areas, its high fecundity and short generation time, its tolerance for anoxia and temperature extremes and its efficient exploitation of the high concentrations of phytoplankton and natural seston at the sediment-water interface may bring it into competition with native species for food and space.

Benthic habitat condition assessments are a requirement under various environmental directives. The Marine Strategy Framework Directive (MSFD), for example, challenges member states in a European sea region to perform comparable assessments of good environmental status and improve coherence of their monitoring programmes by 2020. Currently, North Sea countries operate independent monitoring programmes using nationally defined assessment areas. Lack of an agreed OSPAR or EU scale monitoring method and programme has been identified as a priority science need. This paper proposes a method for the development of a coherent and efficient spatial sampling design for benthic habitats on regional level and gives advice on optimal monitoring effort to get more accurate assessments. We use ecologically relevant assessment areas (strata) across national borders and test spatial sample allocation methods. Furthermore, we investigate the number of samples needed in each stratum to reduce the variance for estimating mean number of taxa and abundance. The stratification needs to take into account the spatial heterogeneity of the entire ecosystem. The total sample effort is optimal when sample allocation takes into account the size and benthic variability within those strata. Change point analysis helps to find a balance between sampling effort and precision of the benthic parameter estimate. A joint sampling design for the North Sea could be generated by combining current efforts, and where needed adapting existing national programmes. This serves a coordinated, region-wide, benthic condition status assessment and strengthens regional cooperation to fulfil multiple monitoring tasks, with a scientifically underpinned common approach.

The potential environmental effect of the brown shrimp fishery in the shallow shelf of the North Sea and Wadden Sea is debated because the fishery operates for a large part in designated Natura2000 sites. In this fishery a beam trawl is pulled along the seafloor, potentially affecting organisms living on and in the seabed. Because the effect by the trawl used in the shrimp fishery is unclear, has long been debated, and hardly studied to date, we carried out an experimental study to test short to medium term effects of the fishery on the benthic community in an area with a decadal long fishery. The study consisted of two complementing parts: one experiment focussed on the effect of a single fishing event in 15 different areas throughout the distribution area of shrimp fishery along the coast and in the Wadden Sea; in another experiment we measured the dose-response relationship between fishing intensity and the benthic community in one area in the Wadden Sea. Unfortunately, the first experiment was severely hampered by unplanned fishing by fishermen. Instead of the originally planned BACI design with 15 replicates, the first experiment was analysed by correlating actual fishing intensity and benthos community parameters. We found a negative relationship between fishing pressure and the change in number of species from pre- (T0) and post-fishing (T1, eight weeks later), but not in total density or Pielou's evenness. In the second experiment the change between T0 and T1, ten weeks later and T2, eight months later) in Pielou's evenness was negatively related to fishing pressure. The change in total density and the number of species were unrelated to fishing intensity. The pattern in evenness was primarily due to the positive relationship of the change of Ensis leei with fishing pressure. For eight of the ten most common individual macrofauna species, there was no relationship between their development and fishing pressure, while for two species the change in density showed a negative relationship with fishing pressure in the T0-T1 (Ascidia sp.) or T0-T2 comparison (Cerastoderma edule). We interpret the observed response in Ensis leei as their ability to relocate and quickly colonise space, that became vacant because the original inhabitants were disturbed, removed or died. Especially this last finding, that an apparently mobile opportunistic species is able to colonise vacant space is a fishery-related mechanism that adds to the understanding of the potential effect of shrimp fisheries.

In dit Syntheserapport worden de relevante bevindingen uit het onderzoek en de monitoring binnen het monitorings- en onderzoeksprogramma PMR NCV gecombineerd om tot een eenduidig antwoord te komen op een aantal onderzoeksvragen. Bij aanvang van het monitoringprogramma van PMR-NCV in 2009 zijn in het Monitoring- en Evaluatie Programma (MEP-NCV) de vragen geformuleerd waarop het monitoringprogramma van de natuurcompensatie een antwoord dient te geven. De synthese van de resultaten en het onderliggende monitoring en onderzoek is uitgevoerd door een consortium onder leiding van Wageningen Marine Research en Deltares. Het doel van de monitoring van de natuurcompensatie in de Voordelta is om antwoord te kunnen geven op de vraag of, middels extra bescherming in de vorm van visserij beperkende maatregelen en de instelling van extra rustgebieden voor zwarte zee-eenden en sterns, voldoende wordt gecompenseerd voor de destijds voorspelde significante effecten als gevolg van de aanleg en aanwezigheid van Maasvlakte 2.

Hoe verloopt de ontwikkeling van infauna gemeenschappen van jaar tot jaar in 2009-2015 in het afgezette sediment op de aangelegde vooroevers van staalslakken en breuksteen bij locatie Zeelandbrug (Zuidhoek-de Val) en Lokkersnol (Cauwersinlaag) in de Oosterschelde en twee referentielocaties in de Oosterschelde?

Sandeel partly spend their life buried in the sediment, without a permanent burrow opening or an inhalant opening in the sediment. We linked the presence of three sandeel species (Ammodytes tobianus, A. marinus and Hyperoplus lanceolatus) off the southern Dutch coast of the North Sea to sediment related environmental variables; (1) sediment composition, with a hypothesized preference for low silt content and high medium-coarse sand content, (2) water velocity near the seabed, with a hypothesized preference for high water velocity and (3) fishing effort of the beam trawl fleet targeting flatfish and shrimp, with a hypothesized negative impact of fishing on sandeel presence. Data originated from an intensive benthic sampling scheme, VMS and logbook databases and a hydrodynamic model. Statistical models were run including these environmental variables plus year, depth, water temperature and salinity. Sandeel presence was negatively correlated with flatfish and shrimp fisheries – both Ammodytes species with flatfish fisheries and H. lanceolatus with shrimp fisheries. Water velocity and silt content were correlated as hypothesized with the presence of all species, and sand content was positively correlated with both Ammodytes species. The remaining environmental variables also showed a significant relation with at least two sandeel species. These findings agree with and greatly expand on previous studies on the relation between sandeel and its environment.

Size-based analyses of marine animals are increasingly used to improve understanding of community structure and function. However, the resources required to record individual body weights for benthic animals, where the number of individuals can reach several thousand in a square metre, are often prohibitive. Here we present morphometric (length–weight) relationships for 216 benthic species from the North Sea to permit weight estimation from length measurements. These relationships were calculated using data collected over two years from 283 stations. For ten abundant and widely dispersed species we tested for significant spatial and temporal differences in morphometric relationships. Some were found, but the magnitude of differences was small in relation to the size-ranges of animals that are usually present and we recommend that the regression relationships given here, based on pooled data, are appropriate for most types of population and community analyses. Our hope is that the availability of these morphometric relationships will encourage the more frequent application of size-based analyses to benthic survey data, and so enhance understanding of the ecology of the benthic/demersal component of marine ecosystems and food webs.

The razor clam Ensis directus was introduced to Europe presumably as larvae in ballast water around 1978. Starting in the German Bight it spread northward and southward along the continental coastline. Currently it is the most common shellfish species in the Dutch coastal zone, where it mainly occurs in the Voordelta and off the Wadden Sea islands. The mean density of E. directus in the Dutch coastal zone increased from around 2–5 individuals m −2 in the late ‘90’s to around 12–19 individuals m −2 from 2002 onwards. Diet studies show that E. directus makes up a significant proportion in the current diet of plaice, sole, dab, flounder and dragonet and in the diet of eider and common scoter. In recent years E. directus contributed 20–100% of the total wet weight in fish stomachs. The proportion E. directus in the diet increases with fish length. Based on stomach contents of oiled and beached birds and of faeces samples the recent frequency of occurrence is 85–90% in eider and 26% in common scoter. Also waders, gulls and corvids prey on E. directus but the contribution to the diet is still unquantified. Because of its great burying depth the species is not easily accessible. Fish either profit from massive die-offs that regularly occur, or they extract (probably only the smaller) individuals from the sediment. Sea ducks can extract E. directus from the sediment, while shorebirds and gulls feed on dying E. directus washing up on the shore. E. directus is possibly an important food item for fish and seabirds when they occur in high densities and in the right size classes. Since the availability depends greatly on massive die-offs, shell size, burying depth and water depth, it is probably not a very reliable food source. Judging from the role E. directus currently plays for the higher trophic levels, its introduction must have caused a major change in the food relations in its distribution area.

Sidescan sonar has been applied in a number of shallow water environments along the Dutch coast to map and monitor shellfish and seabed habitats. The littoral setting of these surveys may hamper data acquisition flying the towfish in zones of turbulence and waves, but also offers valuable opportunities for understanding, interpreting and validating sidescan sonar images because of the ability to ground-truth during low water periods, enabling easy identification and validation. Acoustical images of some of the mussel banks on the tidal flats of the Wadden Sea, recorded at high tide, show a marked resemblance with optical Google Earth images of the same banks. These sonar images may thus serve as 'acoustic type signatures' for the interpretation of sonar patterns recorded in deeper water where ground-truthing is more difficult and more expensive. Similarly, acoustic type signatures of (Japanese) oyster banks were obtained in the estuaries in the southwest of the Netherlands. Automated acoustic pattern recognition of different habitats and acoustical estimation of faunal cover and density are possible applications of sidescan sonar. Both require that the backscattering observed on the sidescan sonar images is directly caused by the biological component of the seafloor. Filtering offers a simple and effective pre-processing technique to separate the faunal signals from linear trends such as emanating from wave ripples or the central tracks of the towfish. Acoustically estimating the faunal density is approached by in-situ counting peaks in backscattering in unit squares. These counts must be calibrated by ground-truthing. Ground-truthing on littoral mussel banks in the Wadden Sea has been carried out by measuring their cover along lines during low tide. Due to its capacity of yielding full-cover, high resolution images of large surfaces, sidescan sonar proves to be an excellent, cost-effective tool for quantitative time-lapse monitoring of habitats. © 2009 Elsevier Ltd. All rights reserved.

We describe an integrated database on European macrobenthic fauna, developed within the framework of the European Network of Excellence MarBEF, and the data and data integration exercise that provided its content. A total of 44 datasets including 465 354 distribution records from soft-bottom macrobenthic species were uploaded into the relational MacroBen database, corresponding to 22 897 sampled stations from all European seas, and 7203 valid taxa. All taxonomic names were linked to the European Register of Marine Species, which was used as the taxonomic reference to standardise spelling and harmonise synonymy. An interface was created, allowing the user to explore, subselect, export and analyse the data by calculating different indices. Although the sampling techniques and intended use of the datasets varied tremendously, the integrated database proved to be robust, and an important tool for studying and understanding large-scale long-term distributions and abundances of marine benthic life. Crucial in the process was the willingness and the positive data-sharing attitude of the different data contributors. Development of a data policy that is highly aware of sensitivities and ownership issues of data providers was essential in the creation of this goodwill.

The pan-European MacroBen database was used to compare the AZTI Marine Biotic Index (AMBI) and the Benthic Quality Index (BQIES), 2 biotic indices which rely on 2 distinct assessments of species sensitivity/tolerance (i.e. AMBI EG and BQI E[S]0.05) and which up to now have only been compared on restricted data sets. A total of 12 409 stations were selected from the database. This subset (indicator database) was later divided into 4 marine and 1 estuarine subareas. We computed E(S50)0.0 in 643 taxa, which accounted for 91.8% of the total abundances in the whole marine indicator database. AMBI EG and E(S50)0.05 correlated poorly. Marked heterogeneities in E(S50)0.0 between the marine and estuarine North Sea and between the 4 marine subareas suggest that sensitivity/tolerance levels vary among geographical areas. High values of AMBI were always associated with low values of BQIES, which underlines the coherence of these 2 indices in identifying stations with a bad ecological status (ES). Conversely, low values of AMBI were sometimes associated with low values of BQIES resulting in the attribution of a good ES by AMBI and a bad ES by BQIES. This was caused by the dominance of species classified as sensitive by AMBI and tolerant by BQIES. Some of these species are known to be sensitive to natural disturbance, which highlights the tendency of BQIES to automatically classify dominant species as tolerant. Both indices thus present weaknesses in their way of assessing sensitivity/tolerance levels (i.e. existence of a single sensitivity/tolerance list for AMBI and the tight relationship between dominance and tolerance for BQIES). Futurestudies should focus on the (1) clarification of the sensitivity/tolerance levels of the species identifiedas problematic, and (2) assessment of the relationships between AMBI EG and E(S50)0.05 within and between combinations of geographical areas and habitats.

Este artículo contiene 14 páginas, 3 tablas, 13 figuras., This study examines whether or not biogeographical and/or managerial divisions across the European seas can be validated using soft-bottom macrobenthic community data. The faunal groups used were: all macrobenthos groups, polychaetes, molluscs, crustaceans, echinoderms, sipunculans and the last 5 groups combined. In order to test the discriminating power of these groups, 3 criteria were used: (1) proximity, which refers to the expected closer faunal resemblance of adjacent areas relative to more distant ones; (2) randomness, which in the present context is a measure of the degree to which the inventories of the various sectors, provinces or regions may in each case be considered as a random sample of the inventory of the next largest province or region in a hierarchy of geographic scales; and (3) differentiation, which provides a measure of the uniqueness of the pattern. Results show that only polychaetes fulfill all 3 criteria and that the only marine biogeographic system supported by the analyses is the one proposed by Longhurst (1998). Energy fluxes and other interactions between the planktonic and benthic domains, acting over evolutionary time scales, can be associated with the multivariate pattern derived from the macrobenthos datasets. Third-stage multidimensional scaling ordination reveals that polychaetes produce a unique pattern when all systems are under consideration. Average island distance from the nearest coast, number of islands and the island surface area were the geographic variables best correlated with the community patterns produced by polychaetes. Biogeographic patterns suggest a vicariance model dominating over the founder-dispersal model except for the semi-closed regional seas, where a model substantially modified from the second option could be supported., The authors acknowledge support by the MarBEF EU-funded Network of Excellence (contract no. GOCE-CT-2003-505446). Support was also received from the UK NERC through PML’s CSRP, and Defra, Project ME3109 and from the Greek National Project on Marine Biodiversity (GSRT).

There is growing evidence that climate change could affectmarine benthic systems. This review provides information of climate change-related impacts on the marine benthos in the North Atlantic. We cover a number of related research aspects, mainly in connection to two key issues. First, is the relationship between different physical aspects of climate change and the marine benthos. This section covers: (a) the responses to changes in seawater temperature (biogeographic shifts and phenology); (b) altered Hydrodynamics; (c) ocean acidification (OA); and (d) sea-level rise-coastal squeeze. The second major issue addressed is the possible integrated impact of climate change on the benthos. This work is based on relationships between proxies for climate variability, notably the North Atlantic Oscillation (NAO) index, and the long-term marine benthos. The final section of our review provides a series of conclusions and future directions to support climate change research on marine benthic systems.

Marine benthic ecosystems are difficult to monitor and assess, which is in contrast to modern ecosystem-based management requiring detailed information at all important ecological and anthropogenic impact levels. Ecosystem management needs to ensure a sustainable exploitation of marine resources as well as the protection of sensitive habitats, taking account of potential multiple-use conflicts and impacts over large spatial scales. The urgent need for large-scale spatial data on benthic species and communities resulted in an increasing application of distribution modelling (DM). The use of DM techniques enables to employ full spatial coverage data of environmental variables to predict benthic spatial distribution patterns. Especially, statistical DMs have opened new possibilities for ecosystem management applications, since they are straightforward and the outputs are easy to interpret and communicate. Mechanistic modelling techniques, targeting the fundamental niche of species, and Bayesian belief networks are the most promising to further improve DM performance in the marine realm. There are many actual and potential management applications of DMs in the marine benthic environment, these are (i) early warning systems for species invasion and pest control, (ii) to assess distribution probabilities of species to be protected, (iii) uses in monitoring design and spatial management frameworks (e.g. MPA designations), and (iv) establishing long-term ecosystem management measures (accounting for future climate-driven changes in the ecosystem). It is important to acknowledge also the limitations associated with DM applications in a marine management context as well as considering new areas for future DM developments. The knowledge of explanatory variables, for example, setting the basis for DM, will continue to be further developed: this includes both the abiotic (natural and anthropogenic) and the more pressing biotic (e.g. species interactions) aspects of the ecosystem. While the response variables on the other hand are often focused on species presence and some work undertaken on species abundances, it is equally important to consider, e.g. biological traits or benthic ecosystem functions in DM applications. Tools such as DMs are suitable to forecast the possible effects of climate change on benthic species distribution patterns and hence could help to steer present-day ecosystem management.

Over centuries dramatic changes have occurred in the species composition of the Wadden Sea, a shallow coastal sea bordering the North Sea. Natural dynamics as well as direct and indirect anthropogenic influences have resulted in the introduction and the disappearance of important benthic populations. Historic records and extensive surveys show large variability in benthic suspension-feeder stocks. Infaunal species like the cockle (Cerastoderma edule) are extremely variable over time and space, hence shows a typical resilient response. Mussel (Mytilus edulis) beds seem to be more stable over time. Once lost, mussel beds need more time to re-establish bed structures. It is hypothesized that infaunal populations have a high resilience, while epifauna species are characterized by resistance to changes as they form structures like reefs or beds. On the basis of this hypothesis the consequences of new introductions can be evaluated. It can be expected that the recent introduction of the resistant reef-building epifaunal Pacific oyster Crassostrea gigas, will lead to shifts in benthic suspension-feeder populations and eventually will develop a new stable state for the Wadden Sea that potentially offers less food for birds. This situation may deviate considerably from the actual nature conservation objectives that focus on the role of the Wadden Sea as one of Europe s most important wetlands for migratory bird populations

In order to investigate the impact of the closure of the Grevelingen estuary on the benthic life and the nursery function of its ebb tidal delta, a comparison was made between the present ebb tidal deltas of the Grevelingen and the Eastern Scheldt. Three groups of benthic animals were compared: macrobenthos, epibenthic animals (including demersal fish) and hyperbenthos. The ebb tidal delta of the Grevelingen is much richer for almost all animal groups discussed. The data suggest that this richness is a consequence of the changes that have occurred in the hydrodynamics since the closure of the Grevelingen estuary in 1971. The area now traps and retains mud, detritus, larvae of different groups of infaunal animals, larvae of epibenthic crustaceans, and eggs and larvae of fish. This change is reflected in the increased importance of the area as a nursery for flatfish, especially dab and sole. However, the increase in the nursery function of the ebb tidal delta does not make up for the loss of nursery areas in the estuary itself.