Climate‐related changes in recruitment of the bivalve Macoma balthica

Abstract

Population dynamics of common intertidal bivalves (Cerastoderma edule, Macoma balthica, Mya arenaria, Mytilus edulis) are strongly related to seawater temperatures. In northwestern European estuaries, series of mild winters followed by low bivalve recruit densities lead to small adult stocks. In this study, we examine temperature-induced effects on reproductive output (eggs m Ϫ2 ), onset of spawning (day of the year), and the juvenile instantaneous mortality rate (per day) of M. balthica. Data analysis was based on an extensive long-term data set originating from the western Wadden Sea. Our results strongly suggest that rising seawater temperatures affect recruitment by a decrease in reproductive output and by spring advancement of bivalve spawning. Apparently, global warming upsets the evolved reproductive strategy of this marine bivalve to tune its reproduction to the most optimal environmental conditions for the first vulnerable life stages, most importantly the match/mismatch of time of spawning with that of the phytoplankton bloom and the settlement of juvenile shrimps on the tidal flats. It is hypothesized that the observed density-dependent mortality of juvenile bivalves may act via competition for food, a behavioral response of shrimp to low spat densities, or be the result of the response of age and size at metamorphosis of marine bivalves to resource variability. It is to be expected that prolonged periods of lowered bivalve recruitment and stocks will lead to a reformulation of estuarine food webs and possibly a reduction of the resilience of the system to additional disturbances, such as the depletion and disturbance by shellfish fisheries.

Long-term variability in bivalve recruitment, mortality, and growth and their contribution to fluctuations in food stocks of shellfish-eating birds

“…Environmental changes to be included in such studies are (1) eutrophication and de-eutrophication (as expressed in e.g. changing concentrations of chlorophyll a and particularly diatoms: Philippart et al 2007), (2) De-eutrophication as a cause of recently low bivalve stocks has been suggested by Brinkman & Smaal (2003) and Ens (2006), climate warming by Beukema (1992), Philippart et al (2003), Beukema & Dekker (2005), and Beukema et al (2009), and fishery disturbance by Piersma et al (2001), Van Gils et al (2006), Piersma (2007), and Kraan et al (2009).…”

The feasibility of offshore aquaculture and its potential for multi-use in the North Sea

“…Also, increased carbon dioxide may cause an acidification of the oceans, which may reduce the shell growth of bivalve molluscs (Gazeau et al 2010). And climate change can affect predator/prey relationships causing a mismatch between spawning, phytoplankton production and predator abundance and consequently high shellfish mortality (Philippart et al 2003). The net result of climate change is hard to predict.…”

Climate Change: Warming Impacts on Marine Biodiversity

“…Differential phenological shifts of prey and predator in response to temperature change might induce temporal mismatches in the occurrence (Fig. 18.3), leading to altered marine trophodynamics (Philippart et al 2003;Edwards and Richardson 2004;Durant et al 2005;Burthe et al 2012;Sommer et al 2012) and consequent declines in commercially important fish stocks such as cod (Beaugrand et al 2003). …”