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Food web structure and function in benthic ecosystems are a reflection of environmental conditions and change in response to both anthropogenic and natural stressors. In Jade Bay (German Wadden Sea), the intertidal macrofauna communities have been intensively studied since the 1930s, and results have revealed pronounced temporal changes in species composition and community structure caused by climatic variability and anthropogenic impacts. Using ecological network analysis, we constructed 3 different food web models representing the status of the 1930s, 1970s and 2009 to assess system development and organization and how the system responded to changing environmental conditions. The biomasses, energetics and trophic exchanges of characteristic macrofauna species were estimated. The total biomass of the benthic communities increased by 70% from the 1930s to the 1970s but declined marginally from the 1970s to 2009. The size of the system in terms of flows through all its compartments increased over time, from 1756 to 2207 to 3464 mg C m−2 d−1 for the 1930s, 1970s and 2009, respectively The amount of material that is recycled in the Jade Bay system declined between the 1930s and 1970s but increased in 2009, when we also found greater efficiency at retaining material within the food web until it leaves the system. The internal organization of the benthic ecosystem is characterized by short trophic pathways. Indices of system development and organization increased over time. There was a noticeable decline in parallel trophic pathways, indicating a reduction in the ability of the system to withstand perturbations.

The food webs of the 3 main reaches of the Ems estuary were analysed for 1975–1980 using Ecological Network Analysis (ENA). Aspects related to model aggregation at a high species resolution level (ALL SPP) or using functional groups (F-GR) and at 4 spatial scales (3 reaches and entire system) are cast in 24 balanced carbon flow models with 20 to 57 ENA compartments. Highest biomasses are represented by true phytoplankton, resuspended microphytobenthos, microphytobenthos, benthic bacteria, dissolved and particulate organic carbon. The bivalves Limecola balthica and Mya arenaria represent the highest animal biomass, while Crangon crangon plays a central role in the network connections. In an upstream direction, there are clear gradients in the relative overhead (Φ/DC: 0.610–0.599–0.534 [values for the 3 reaches]) and the relative ascendency (A/DC: 0.390–0.401–0.466). The A/DC values decrease when the non-living compartments (detritus) as well as the living compartments (species, functional groups) are hand-balanced. The A/DC values increase when the models are balanced by the available AVG2 balancing routine. The Φ/DC values show opposite trends. For the ALL SPP models, the geometric mean trophic efficiencies (MTE) decrease in an upstream direction (2.71–1.01–0.89) while the Finn cycling indices (FCI) increase (10–8.4–16.6%), as do the detritivory/herbivory ratios (3.13–4.33–9.03). Application of ENA to reaches instead of a full system is therefore suggested. Since ENA is sensitive to relatively small quantitative changes in biomass input values, the preferred user protocol is to consider all the relevant species separately, and to hand-balance the flows of living as well as non-living compartments.

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.

International efforts to assess the status of marine ecosystems have been hampered by insufficient observations of food web interactions across many species, their various life stages, and their geographic ranges. Hence, we collated data from multiple databases of fish stomach contents from samples taken across the North Atlantic and Arctic oceans containing 944 129 stomach samples from larvae to adults, with 14 196 unique interactions between 227 predator species and 2158 prey taxa. We use these data to develop a reproducible data-driven approach to classifying broad functional feeding guilds and then apply these to fish survey data from the north-east Atlantic shelf seas to reveal spatial and temporal changes in ecosystem structure and functioning. In doing so, we construct individual predator–prey body-mass scaling models to predict the biomass of prey functional groups, e.g. zooplankton, benthos, and fish, for different predator species. These predictions provide empirical estimates of species- and size-specific feeding traits of fish, such as predator–prey mass ratios, individual prey mass, and the biomass contribution of different prey to predator diets. The functional groupings and feeding traits provided here help to further resolve our understanding of interactions within marine food webs and support the use of trait-based indicators in biodiversity assessments. The data used and predictions generated in this study are published on the Cefas Data Hub at https://doi.org/10.14466/CefasDataHub.149 (Thompson et al., 2024).

Satellite synthetic aperture radar (SAR) holds a high potential for remote sensing in intertidal areas. Geomorphic structures of the sediment surface generating patterns of water cover contrasting with exposed sediment surfaces can clearly be detected. This study explores intertidal bedforms on the upper flats bordering the island of Norderney in the German Wadden Sea using TerraSAR-X imagery from 2009 to 2015. Such bedforms are common in the Wadden Sea, forming crests alternating with water-covered troughs oriented in a north-easterly direction. In the western Norderney area, the crest-to-crest distance ranges from 50–130 m, and bedform length can reach 500 m. Maximum height differences between crests and troughs are 20 cm. A simple method is developed to extract the water-covered troughs from TerraSAR-X images for spatiotemporal analysis of bedform positions in a GIS. It is earmarked by unsupervised ISODATA classification of textural parameters, contrasting with various algorithm-based methods pursued in earlier studies of waterline detection. The high-frequency TerraSAR-X data reveal novel evidence of a bedform shift in an easterly direction during the study period. Height profiles measured with RTK-DGPS along defined transects support the findings from TerraSAR-X data. First investigations to characterise sediments and macrofauna show that benthic macrofauna community structure differs significantly between crests and troughs, comprising mainly fine sands. Evidently, bedform formation has implications for benthic faunal diversity in back-barrier settings of the Wadden Sea. SAR remote sensing provides pivotal data on bedform dynamics.

The Wadden Sea is an important habitat for a large number of fish species, supporting functions such as reproduction, breeding and feeding. The hooknose ( Agonus cataphractus , Linnaeus, 1758) is a resident demersal fish species of the Wadden Sea, but due to its non-commercial importance it is rarely studied. In the present study, the feeding strategy and prey selection of the hooknose related to the benthic in- and epifauna in the field were investigated in six different habitat types (circalittoral sand, circalittoral mud, circalittoral mixed sediments, circalittoral coarse and gravel sediments, sublittoral sandbanks and reefs) in coastal waters of the German Wadden sea between 2020 and 2021. The stomach contents of A. cataphractus were dominated in most of the habitat types by very mobile epibenthic prey species, mainly the brown shrimp ( Crangon crangon , Linnaeus, 1758), amphipods ( Ampelisca spp., Microprotopus maculatus , Norman 1867) and cumaceans ( Diastylis bradyi , Norman 1879, Pseudocuma longicorne , Bate 1858), similar to the benthic communities in the field. Infauna species such as the tube-building polychaete Lanice conchilega (Pallas 1766) were rarely consumed and potentially avoided due to their ability to withdraw below the feeding depths. Our results further showed habitat-specific differences in the hooknose diet, especially in reefs, where skeleton shrimps (caprellids) dominated the diet. The habitat type also influences the condition of A. cataphractus being highest in reefs but lowest on sandbanks. Our results highlight the importance of knowledge functional relationships between smaller-sized Wadden Sea fish species and its typical habitats, which in turn is essential for applicable management measures of the whole Wadden Sea area.

The effects of selecting system compartments in the calculation of Ecological Network Analysis (ENA) indices were studied based on data collected in the 3 main reaches of the Ems estuary. For each reach, ENA was applied to (1) a set of carbon flow models in which only the living compartments were hand-balanced, and (2) a set in which living and non-living compartments were hand-balanced. The models considered represent a full food web at the highest species resolution level and 4 food web subsets representing benthic macrofauna, benthic macrofauna plus demersal fish and epifauna, all fish, and all birds. Each of the 30 models consist of 11 to 57 compartments (species, functional groups, C-pools). Results demonstrate that the food web subsets are predominantly responsible for the variation in the ENA indices (relative ascendency: 15% of its maximum of 1; internal relative ascendency: 21%). The use of food web subsets also leads to increased variation in the Finn cycling index, effective link density, trophic depth and robustness. The use of subsets is therefore discouraged. The added value of robustness as a practical index was explored in relation to ascendency-related (i.e. information-related) indices, but its use could not be supported because its range was too limited. The results also indicate that incomplete food webs significantly influence the size of the ‘window of vitality’. ENA works well when food web subsets include the full trophic biomass pyramid, but top-down studies focussing on so-called iconic species are not advisable for assessments. The closer to the full food web, the better the results of ENA correspond with those of a full food web.

Invasions of marine species are changing coastal food webs worldwide, impacting on trophic interactions between native species (e.g. predator–prey relationships). Here, the impact of 3 macrozoobenthic invasive species on food web structure and functioning at Balgzand (western Wadden Sea) is quantified by using ecological network analysis (ENA). The bivalves Ensis leei and Magallana gigas were observed for the first time in 1984 and 2001, respectively, and the polychaete Marenzelleria viridis appeared in 1989. Although E. leei and M. viridis reached similar peak biomasses in the 2000s (ca. 1700 and 2000 mg C m−2, respectively), the bivalve consumption was higher (>45% of total consumption) than that of the polychaete (<0%). Biomass and impact of M. gigas remained relatively low. E. leei occupied an ecological niche that was relatively unoccupied, which led to competitive advantage with respect to other suspension feeders. Increasing biomass of E. leei coincided with a 70% increase of trophic carbon transfer from primary to secondary producers and an 80% increase from secondary producers to detritus. Carbon flows from secondary producers to higher trophic levels were reduced by more than 60%. These shifts in trophic transfer were stronger than those observed during the invasion of M. gigas in the NE Wadden Sea. At Balgzand, biomass of M. gigas and M. viridis rapidly declined to low values in the 2010s, implying a temporally limited impact. In the 2010s, E. leei was still responsible for 30% of the total consumption in the 2010s, indicating a longer-term impact.

International efforts to assess the status of marine ecosystems have been hampered by insufficient observations of food web interactions across many species, their various life stages, and their geographic ranges. Hence, we collated data from multiple databases of fish stomach contents from samples taken across the North Atlantic and Arctic oceans containing 944 129 stomach samples from larvae to adults, with 14 196 unique interactions between 227 predator species and 2158 prey taxa. We use these data to develop a reproducible data-driven approach to classifying broad functional feeding guilds and then apply these to fish survey data from the north-east Atlantic shelf seas to reveal spatial and temporal changes in ecosystem structure and functioning. In doing so, we construct individual predator–prey body-mass scaling models to predict the biomass of prey functional groups, e.g. zooplankton, benthos, and fish, for different predator species. These predictions provide empirical estimates of species- and size-specific feeding traits of fish, such as predator–prey mass ratios, individual prey mass, and the biomass contribution of different prey to predator diets. The functional groupings and feeding traits provided here help to further resolve our understanding of interactions within marine food webs and support the use of trait-based indicators in biodiversity assessments. The data used and predictions generated in this study are published on the Cefas Data Hub at https://doi.org/10.14466/CefasDataHub.149 (Thompson et al., 2024).

The contribution of sediments to nutrient cycling of the coastal North Sea is strongly controlled by the intensity of fluxes across the sediment water interface. Pore-water advection is one major exchange mechanism that is well described by models, as it is determined by physical parameters. In contrast, biotransport (i.e., bioirrigation, bioturbation) as the other major transport mechanism is much more complex. Observational data reflecting biotransport, from the German Bight for example, is scarce. We sampled the major sediment provinces of the German Bight repeatedly over the years from 2013 to 2019. By employing ex situ whole core incubations, we established the seasonal and spatial variability of macrofauna-sustained benthic fluxes of oxygen and nutrients. A multivariate, partial least squares analysis identified faunal activity, in specifically bioturbation and bioirrigation, alongside temperature, as the most important drivers of oxygen and nutrient fluxes. Their combined effect explained 63% of the observed variability in oxygen fluxes, and 36–48% of variability in nutrient fluxes. Additional 10% of the observed variability of fluxes were explained by sediment type and the availability of plankton biomass. Based on our extrapolation by sediment provinces, we conclude that pore-water advection and macrofaunal activity contributed equally to the total benthic oxygen uptake in the German Bight.