The diversity and structure of ecosystems has been found to depend both on trophic interactions in food webs and on other species interactions such as habitat modification and mutualism that form non-trophic interaction networks. However, quantification of the dependencies between these two main interaction networks has remained elusive. In this study, we assessed how habitat-modifying organisms affect basic food web properties by conducting in-depth empirical investigations of two ecosystems: North American temperate fringing marshes and West African tropical seagrass meadows. Results reveal that habitat-modifying species, through non-trophic facilitation rather than their trophic role, enhance species richness across multiple trophic levels, increase the number of interactions per species (link density), but decrease the realized fraction of all possible links within the food web (connectance). Compared to the trophic role of the most highly connected species, we found this non-trophic effects to be more important for species richness and of more or similar importance for link density and connectance. Our findings demonstrate that food webs can be fundamentally shaped by interactions outside the trophic network, yet intrinsic to the species participating in it. Better integration of non-trophic interactions in food web analyses may therefore strongly contribute to their explanatory and predictive capacity.

The sandy seabed of shallow coastal shelf seas displays morphological patterns of various dimensions. The seabed also harbors a rich ecosystem. Increasing pressure from human‐induced disturbances necessitates further study on drivers of benthic community distributions over morphological patterns. Moreover, a greater understanding of the sand ripple distribution over tidal sand waves may improve morphological model predictions. Here we analyzed the biotic abundance and ripple morphology in sand wave troughs and crests using video transects. We found that both the epibenthos and endobenthos are significantly more abundant in sand wave troughs, where ripples are less abundant and more irregularly shaped. Finally, we show that camera systems are relatively quick and effective tools to study biotic spatial patterns in relation to seabed morphology.

The European Commission landing obligation, including species-specific “high survival” exemptions, has established a need for accurate discard survival estimates. This study presents the first discard survival estimates on-board Dutch commercial pulse trawlers. During seven, six, and one fishing trip(s), respectively, undersized plaice (Pleuronectes platessa), sole (Solea solea), and dab (Limanda limanda) were collected, assessed for vitality and subsequently monitored up to 21 days. Uncorrected for any potential impacts from predation, tagging, research-related handling, or holding conditions overall survival for plaice (n = 349), sole (n = 226), and dab (n = 187) was assessed as 15% [95% CI: 11–19%], 29% [95% CI: 24–35%], and 16% [95% CI: 10–26%] respectively. Survival was mainly effected by water temperature and factors linked to the fishing vessel. Fish length was not found to affect survival. Catch processing time and haul duration affected plaice survival but not sole. Vitality index, which averages reflex impairment and external damage scores, correlated with survival and may be developed as a proxy for discard survival. Compared to tickler-chain beam trawlers, pulse trawlers showed relatively higher discard survival under fishing conditions pertinent to these studies.