Data from: Mollusc-shell debris can mitigate the deleterious effects of organic pollution on marine sediments

Organic pollution is widespread in coastal areas and can have profound
impacts on the seabed. Coastal sediments play an important role at a
global scale in the recycling of organic matter, and this process is
influenced by the habitat complexity of the sediments, among other
factors. Mollusc shells are produced as a waste product from a range of
anthropogenic activities, but we demonstrate that they can be used to
increase the habitat complexity of sediments. We studied the effect of
mussel-shell debris (shell-hash) on the biogeochemical processes of marine
sediments affected by organic pollution, using a mesocosm experiment
simulating the bioturbation effects of macrofauna. We found that
shell-hash improved the ecological status of organically polluted
sediments by reducing the accumulation of sulphide from anaerobic
metabolic pathways. Additionally, when shell-hash was present in an
organically polluted sediment, there was a decrease in ammonium release to
the water column, thus preventing the negative ecological consequences of
eutrophication. Synthesis and applications. Our study indicates that
shell-hash debris can be used as a potential tool to mitigate the effects
of organic enrichment on marine sediments. A density of shell-hash debris
of 1900 g m−2 in the sediment can diminish toxic by-products (sulphides
and ammonium) derived from the stimulation of anaerobic metabolic pathways
by organic pollution, at levels that are biologically relevant. The
mitigation effect of shell-hash is more pronounced in sediments where
macrofauna is not present.