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Benthos has long been recognized as an important factor influencing local sediment stability, deposition, and erosion rates. However, its role in long-term (annual to decadal scale) and large-scale coastal morphological change remains largely speculative. This study aims to derive a quantitative understanding of the importance of benthos in the morphological development of a tidal embayment (Jade Bay) as representative of tidal coastal regions. To achieve this, we first applied a machine-learning-aided species abundance model to derive a complete map of benthos (functional groups, abundance, and biomass) in the study area, based on abundance and biomass measurements. The derived data were used to parameterize the benthos effect on sediment stability, erosion rates and deposition rates, erosion and hydrodynamics in a 3-dimensional hydro-eco-morphodynamic model, which was then applied to Jade Bay to hindcast the morphological and sediment change for 2000–2009. Simulation results indicate significantly improved performance with the benthos effect included. Simulations including benthos show consistency with measurements regarding morphological and sediment changes, while abiotic drivers (tides, storm surges) alone result in a reversed pattern in terms of erosion and deposition contrary to measurement. Based on comparisons among scenarios with various combinations of abiotic and biotic factors, we further investigated the level of complexity of the hydro-eco-morphodynamic models that is needed to capture long-term and large-scale coastal morphological development. The accuracy in the parameterization data was crucial for increasing model complexity. When the parameterization uncertainties were high, the increased model complexity decreased the model performance. [ABSTRACT FROM AUTHOR]

Benthos has long been recognized as an important factor influencing local sediment stability, deposition and erosion rates. However, its role in long-term (annual-to-decadal scale) and large-scale coastal morphological change remains largely speculative. This study aims to derive a quantitative understanding of the importance of benthos in the morphological development of a tidal embayment (Jade Bay), as representative for tidal coastal regions. To achieve this, we firstly applied a machine learning-aided species abundance model to derive a complete map of benthos (functional groups, abundance and biomass) in the study area, based on abundance and biomass measurements. The derived data were used to parameterize the benthos effect on sediment stability, erosion/deposition rates, and hydrodynamics in a 3-dimensional hydro-eco-morphodynamic model, which was then applied to the Jade Bay to hindcast morphological and sediment change for 2000–2009. Simulation results indicate significantly improved performance with benthos effect included. Results suggest that the model is able to reproduce the main pattern of morphological change only when benthos impact is included, whilst abiotic drivers (tides, storm surges) alone would lead to an opposite pattern. Based on comparison among scenarios with various combinations of abiotic and biotic factors, we further investigated the level of complexity of hydro-eco-morphodynamic models that is needed to capture long-term and large-scale coastal morphological development. The accuracy in parametrization data was crucial for increasing model complexity. When the parametrization uncertainties were high, increased model complexity decreased model performance. [ABSTRACT FROM AUTHOR]

Climate change affects the marine environment on many levels with profound consequences for numerous biological, chemical, and physical processes. Benthic bioturbation is one of the most relevant and significant processes for benthic-pelagic coupling and biogeochemical fluxes in marine sediments, such as the uptake, transport, and remineralisation of organic carbon. However, only little is known about how climate change affects the distribution and intensity of benthic bioturbation of a shallow temperate shelf sea system such as the southern North Sea. In this study, we modelled and projected changes in bioturbation potential (BPp) under a continuous global warming scenario for seven southern North Sea key bioturbators: Abra alba, Amphiura filiformis, Callianassa subterranea, Echinocardium cordatum, Goniada maculata, Nephtys hombergii, and Nucula nitidosa. Spatial changes in species bioturbation intensity are simulated for the years 2050 and 2099 based on one species distribution model per species driven by bottom temperature and salinity changes using the IPCC SRES scenario A1B. Local mean bottom temperature was projected to increase between 0.15 and 5.4 ℃, while mean bottom salinity was projected to moderately decrease by 1.7. Our results show that the considered benthic species are strongly influenced by the temperature increase. Although the total BP remained rather constant in the southern North Sea, the BPp for four out of seven species was projected to increase, mainly due to a simultaneous northward range expansion, while the BPp in the core area of the southern North Sea declined for the same species. Bioturbation of the most important species, Amphiura filiformis and Echinocardium cordatum, showed no substantial change in the spatial distribution, but over time. The BPp of E. cordatum remained almost constant until 2099, while the BPp of A. filiformis decreased by 41%. The northward expansion of some species and the decline of most species in the south led to a change of relative contribution to bioturbation in the southern North Sea. These results indicate that some of the selected key bioturbators in the southern North Sea might partly compensate the decrease in bioturbation by others. But especially in the depositional areas where bioturbation plays a specifically important role for ecosystem functioning, bioturbation potential declined until 2099, which might affect the biochemical cycling in sediments of some areas of the southern North Sea. [ABSTRACT FROM AUTHOR]

Regime shifts may cause an intrinsic decrease in the potential predictability of marine ecosystems. In such cases, forecasts of biological variables fail. To improve prediction of long-term variability in environmental variables, we constructed a multivariate climate index and applied it to forecast ecological time series. The concept is demonstrated herein using climate and macrozoobenthos data from the southern North Sea. Special emphasis is given to the influence of selection of length of fitting period to the quality of forecast skill especially in the presence of regime shifts. Our results indicate that the performance of multivariate predictors in biological forecasts is much better than that of single large-scale climate indices, especially in the presence of regime shifts. The approach used to develop the index is generally applicable to all geographical regions in the world and to all areas of marine biology, from the species level up to biodiversity. Such forecasts are of vital interest for practical aspects of the sustainable management of marine ecosystems and the conservation of ecosystem goods and services. [ABSTRACT FROM AUTHOR]

We compiled data from different monitoring surveys to analyse and compare community and diversity patterns of fish, epi- and infauna in the German Exclusive Economic Zone (EEZ) of the North Sea in order to identify benthic habitats common to all faunal components. We found congruent community patterns of fish, epi- and infauna for the coastal waters, the Oysterground and the area called 'Duck's Bill', which coincided with specific abiotic characteristics of these regions. The three regions were defined as special habitats for fish, epi- and infauna species in the German EEZ. The differences in the seasonal variability of abiotic factors seem to be the most important discriminating abiotic characteristic for the three habitats. The spatial distribution of fish, epifauna and infauna communities remained stable over time although habitat characteristics such as sea surface temperature increased due to climate change. However, it is expected that the coastal habitat will be more sensitive to future climate change effects in contrast to the Oysterground and Duck's Bill habitat. [ABSTRACT FROM AUTHOR]

Abstract: The North Sea Benthos Project 2000 was initiated as a follow-up to the 1986 ICES North Sea Benthos Survey with the major aim to identify changes in the macrofauna species distribution and community structure in the North Sea and their likely causes. The results showed that the large-scale spatial distribution of macrofauna communities in the North Sea hardly changed between 1986 and 2000, with the main divisions at the 50 m and 100 m depth contours. Water temperature and salinity as well as wave exposure, tidal stress and primary production were influential environmental factors on a large (North Sea-wide) spatial scale. The increase in abundance and regional changes in distribution of various species with a southern distribution in the North Sea in 2000 were largely associated with an increase in sea surface temperature, primary production and, thus, food supply. This can be most likely related to the North Sea hydro-climate change in the late 1980s influenced by the variability in the North Atlantic Oscillation (NAO). Only one cold-temperate species decreased in abundance in 2000 at most of the stations. Indications for newly established populations of offshore non-native species were not found. Differences in macrofauna community structure on localised spatial scales were predominantly found north of the 50 m depth contour off the British coast along the Flamborough Head Front towards the Dogger Bank, off the coast of Jutland and at the Frisian Front. These changes were most likely attributed to stronger frontal systems in 2000 caused by the increased inflow of Atlantic water masses in relation to the hydro-climate change in the late 1980s. [Copyright &y& Elsevier]

Benthic epifauna was sampled in an area of 10 × 10 nautical miles in the German Bight. Samples were taken in January and July/August from 1998 to 2009. The ecological functioning of the epifaunal community was assessed using biological traits analysis (BTA). Twelve ecological traits of 26 epifaunal species were considered and analysed using non-metric multidimensional scaling (nmMDS). Anomalies in the sea surface temperature (SST) close to the study area were mainly above the long-term mean during the study period. SST was exceptionally high during the autumn months between 2002 and 2006. Additionally, the cold winter of 1995-96 was clearly reflected in strong negative SST anomalies. Trait composition changed in 2002, mainly due to a decreasing trend of traits related to an opportunistic life mode from 1998-2002. Traits related to reproduction showed a much clearer response to the high autumn SST anomalies from 2002 to 2006 than other traits. We concluded that the cold winter resulted in an increase in opportunistic species in the study area followed by characteristic post-disturbance succession stages to the point of an established community in 2002. This indicates a recovery time of epifaunal communities in the German Bight of 7-8 years. Additionally, the results give evidence that climate-induced variability of SST in the German Bight affects mainly the reproduction of epifaunal species rather than other traits such as feeding type. [ABSTRACT FROM AUTHOR]

Abstract: An essential prerequisite for the assessment of the ecological quality of marine ecosystems is the understanding of the natural variability and its effect on the performance of quality indices. This study is focused on the long-term natural variability of diversity, biotic and multimetric indices by using long-term macrofauna data of a coastal area in the southern North Sea (1978–2005). The univariate and most biotic and multimetric indices respond significantly on specific natural disturbance events such as cold winters, but the strength of response varied between indices as well as between events. As a result, the ecological quality status can decrease over a range of 3 (out of 5) classification units. The overall ecological quality was good to high, but an increase of indices occurred from the mid 1980s onwards due to changes in the climate regime. This long-term variability has to be considered within ecological quality assessment schemes. [Copyright &y& Elsevier]

In the marine realm, climate change can affect a variety of physico-chemical properties with wide-ranging biological effects, but the knowledge of how climate change affects benthic distributions is limited and mainly restricted to coastal environments. To project the response of benthic species of a shelf sea (North Sea) to the expected climate change, the distributions of 75 marine benthic species were modelled and the spatial changes in distribution were projected for 2099 based on modelled bottom temperature and salinity changes using the IPCC scenario A1B. Mean bottom temperature was projected to increase between 0.15 and 5.4 °C, while mean bottom salinity was projected to moderately increase by 1.7. The spatial changes in species distribution were modelled with Maxent and the direction and extent of these changes were assessed. The results showed a latitudinal northward shift for 64% of the species (maximum 109 km; brittle star Ophiothrix fragilis ) and a southward shift for 36% (maximum 101 km; hermit crab Pagurus prideaux and the associated cloak anemone Adamsia carciniopados ; 105 km). The relatively low rates of distributional shifts compared to fish or plankton species were probably influenced by the regional topography. The environmental gradients in the central North Sea along the 50 m depth contour might act as a ‘barrier’, possibly resulting in a compression of distribution range and hampering further shifts to the north. For 49 species this resulted in a habitat loss up to 100%, while only 11 species could benefit from the warming in terms of habitat gain. Particularly the benthic communities of the southern North Sea, where the strongest temperature increase was projected, would be strongly affected by the distributional changes, since key species showed northward shifts and high rates of habitat loss, with potential ramifications for the functioning of the ecosystem. [ABSTRACT FROM AUTHOR]

Analysis of ecosystem functioning is essential to describe the ecological status of ecosystems and is therefore directly requested in international directives. There is a lack of knowledge regarding functional aspects of benthic communities and their environmental and anthropogenic driving forces in the southern North Sea. This study linked functional composition of epibenthic communities to environmental conditions and fishing effort and investigated spatial correlations between habitat characteristics to gain insight into potential synergistic and/or cumulative effects. Functional composition of epifauna was assessed by using biological trait analysis (BTA), which considered 15 ecological traits of 54 species. Functional composition was related to ten predictor variables derived from sediment composition, bottom temperature and salinity, hydrodynamics, annual primary production and fishing effort. Our results revealed significantly different functional composition between the Dogger Bank, the Oyster Ground, the West and North Frisian coast. Mobility, feeding type, size and adult longevity were the most important traits differentiating the communities. A high proportion of trait modalities related to an opportunistic life mode were obvious in coastal areas especially at the West Frisian coast and in the area of the Frisian Front indicating disturbed communities. In contrast, functional composition in the Dogger Bank area indicated undisturbed communities with prevalence of large, long-lived and permanently attached species being sensitive towards disturbance such as fishing. Tidal stress, mud content of sediments, salinity, stratification and fishing effort were found to be the most important habitat characteristics shaping functional composition. Strong correlations were found between variables, especially between those which changed gradually from the coast to offshore areas including fishing effort. Unfavourable extremes of these factors in coastal areas resulted in disturbed epibenthic communities, while the relative influence of a single factor on functional composition cannot be quantified. Coastal communities seemed to be well adapted to disturbance and the prevalence of opportunistic trait modalities not necessarily revealed a poor ecological status according to the Marine Strategy Framework Directive (MSFD). The integration of functional aspects into the assessment of ecosystem health is recommended, since widely used structural measures failed in naturally disturbed habitats. [ABSTRACT FROM AUTHOR]

Climate change is a global threat for marine ecosystems, their biodiversity and consequently ecosystem services. In the marine realm, marine protected areas (MPAs) were designated to counteract regional pressures, but they might be ineffective to protect vulnerable species and habitats, if their distribution is affected by global climate change. We used six Species Distribution Models (GLM, MARS, FDA, RF, GBM, MAXENT) to project changes in the distribution of eight benthic indicator and key species under climate change in the North Sea MPAs for 2050 and 2099. The projected distribution area of most species will be stable or even increase within the MPAs between 2001 and 2050. Thereafter, the distribution area decreased, especially within MPAs in the central North Sea by 2099, and some key species even disappeared from the MPAs. Consequently, the monitoring and protection of benthic species might not be possible within static MPA borders under climate change. 1. Distributional changes will be most pronounced for the second half of the century 2. MPAs in the North Sea might not fulfil their objectives in the far future 3. Machine learning and regression-based methods showed high performance variation 4. Consensus models were an appropriate approach to reduce this variation [ABSTRACT FROM AUTHOR]

Full-coverage spatial data of occurrence and a detailed description of habitat requirements of epibenthic communities are needed in many conservation and management contexts. In the North Sea the focus has so far been on small benthic infauna, whereas structure and ecosystem functions of larger epifaunal communities have been largely ignored. This study provides a comprehensive analysis of epibenthic community structure in the south-eastern North Sea, including a detailed inventory of species, diversity and spatially contiguous distribution of communities. Data from nearly 400 stations were compiled for the study, enabling us to describe epibenthic community structure at unprecedented spatial resolution. Eight distinct epibenthic communities were found in the south-eastern North Sea by using multivariate analysis. Distribution modelling with eight environmental variables (bottom temperature and salinity, temperature differences between summer and winter, mud content of sediments, maximum bottom shear stress, stratification, water depth and annual primary production) and one human pressure (fishing effort) was used to extrapolate probable spatial distributions and to identify associated habitat characteristics of the communities in the south-eastern North Sea. Three large epibenthic communities “Coast”, “Oysterground” and “Tail End” reflect a gradual habitat change from the coast towards offshore regions, expressed in gradients of bottom salinity, seasonal temperature differences and stratification as the dominant environmental factors. Five smaller communities (“Amrum Bank”, “Frisian Front”, “Deeps”, “Dogger Bank” and “Dogger Slope”) outline specific habitats in the south-eastern North Sea. The “Dogger Slope” community has not been recognized before, but has a predicted spatial extent of 7118 km 2 . Due to the high occurrence of long-lived, sessile species such as sponges this community is very sensitive to demersal fishing. [ABSTRACT FROM AUTHOR]