Groundfîsh overfishing, diatom decline, and the marine silica cycle: Lessons from Saanich Inlet, Canada, and the Baltic Sea cod crash

Timor Katz*, Gitai Yahel, Ruthy Yahel, Verena Tunnicliffe, Barak Herut, Paul Snelgrove, John Crusius, Boaz Lazar

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

18 Scopus citations

Abstract

In this study, we link groundfish activity to the marine silica cycle and suggest that the drastic mid-1980s crash of the Baltic Sea cod (Gadus morhua) population triggered a cascade of events leading to decrease in dissolved silica (DSi) and diatom abundance in the water. We suggest that this seemingly unrelated sequence of events was caused by a marked decline in sediment resuspension associated with reduced groundfish activity resulting from the cod crash. In a study in Saanich Inlet, British Columbia, Canada, we discovered that, by resuspending bottom sediments, groundfish triple DSi fluxes from the sediments and reduce silica accumulation therein. Using these findings and the available oceanographie and environmental data from the Baltic Sea, we estimate that overfishing and recruitment failure of Baltic cod reduced by 20% the DSi supply from bottom sediments to the surface water leading to a decline in the diatom population in the Baltic Sea. The major importance of the marginal ocean in the marine silica cycle and the associated high population density of groundfish suggest that groundfish play a major role in the silica cycle. We postulate that dwindling groundfish populations caused by anthropogenic perturbations, e.g., overfishing and bottom water anoxia, may cause shifts in marine phytoplankton communities.

Original languageEnglish
Article numberGB4032
JournalGlobal Biogeochemical Cycles
Volume23
Issue number4
DOIs
StatePublished - Oct 2009

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