In coastal systems, planktonic and benthic silicifiers compete for the pool of dissolved silicon, a nutrient required to make their skeletons. The contribution of planktonic diatoms to the silicon cycle in coastal systems is often well characterized, while that of benthic silicifiers such as sponges has rarely been quantified. Herein, silicon fluxes and stocks are quantified for the sponge fauna in the benthic communities of t...

Realistic assessments of the ecological status of benthic habitats, as requested by European directives such as the Water Framework Directive and the European Marine Strategy Framework Directive, require biotic indices capable of detecting anthropogenic impact without having preliminary knowledge of the occurring pressures. In this context, a new general-purpose biotic index (GPBI) based on the deviation of benthic macrofauna...

Under climate change, many Arctic coastal ecosystems receive increasing amounts of freshwater, with ecological consequences that remain poorly understood. In this study, we investigated how freshwater inputs may affect the small‐scale structure of benthic food webs in a low‐production high‐Arctic fjord (Young Sound, NE Greenland). We seasonally sampled benthic invertebrates from two stations receiving contrasting freshwater in...

The silicic acid (DSi) is a dissolved nutrient used by diverse marine organisms to build their skeletons of biogenic silica (BSi). This consumption, mostly due to diatoms, largely determines the availability of DSi in the photic ocean. Yet growing evidence suggests that Si consumers traditionally disregarded, such as the siliceous sponges, may also play a role. This study investigated the kinetics of DSi utilization by two dem...

Time series of environmental measurements are essential for detecting, measuring and understanding changes in the Earth system and its biological communities. Observational series have accumulated over the past 2–5 decades from measurements across the world's estuaries, bays, lagoons, inland seas and shelf waters influenced by runoff. We synthesize information contained in these time series to develop a global view of changes...

Ecological shifts from diatoms to other phytoplankton species have been related to decreasing Si : N and Si : P nutrient ratios. The Bay of Brest is such a perturbated ecosystem where Si has become limiting but where diatoms continue to dominate the phytoplankton throughout the productive period. Several hypothesis have been invoked to account for this dilemma. The most recent combines suspension feeder activity and Si recycli...

In this review, using examples drawn from field observations or experimental studies, our goals are (i) to briefly summarize the major changes, in terms of species composition and functional structure, occurring in phyto and zoobenthic communities in relation to nutrient enrichment of the ecosystems; particular interest is given to the major abiotic and biotic factors occurring during the eutrophication process, (ii) to discus...