Rising water temperatures, reproduction and recruitment of an invasive oyster, Crassostrea gigas, on the French Atlantic coast

Abstract

The recent appearance and invasion of feral oysters (Crassostrea gigas) along the northern European Atlantic coast, underscores the necessity to investigate the relationship between environmental variables, reproductive physiology, larval development and recruitment. We studied these relationships at both high (HT) and intermediate (IT) - turbidity sites, through historical data on water temperatures, multi-parameter environmental probes, histological analyses, and field collections of planktonic larvae and settled post-larvae in 2005 and 2006. A progressive warming trend was observed, especially since 1995, when oyster proliferation first became severe. Threshold temperatures for oocyte growth, larval development and settlement were achieved in both 2005 and 2006. The HT site showed greater numbers of larvae and post-larvae than the IT site for both years, with the highest numbers of post-larvae observed at both sites during the warmer summer of 2006. These results suggest that increased temperatures in northern European waters allow successful reproduction, larval development, and recruitment of C. gigas. High turbidity conditions further enhance this success.

Satellite remote sensing reveals a positive impact of living oyster reefs on microalgal biofilm development

“…In Europe, it was massively imported in the 1970s and rapidly became the main cultivated species, following the decline of previously farmed oysters which had been struck by large-scale epizootic outbreaks (Grizel and Héral, 1991;Humphreys et al, 2014). During recent decades, C. gigas benefited from coastal eutrophication and rising sea temperature (Thomas et al, 2016), resulting in a poleward expansion of its distribution (Dutertre et al, 2010) and the formation of dense reefs along many coastal areas (Diederich, 2006;Brandt et al, 2008;Le Bris et al, 2016). In some ecosystems, wild C. gigas is now considered as a trophic competitor of its cultivated conspecifics (Cognie et al, 2006).…”

Recruitment of the Pacific oyster Crassostrea gigas in a shellfish-exploited Mediterranean lagoon: discovery, driving factors and a favorable environmental window

“…gigas has been widely studied all over the world, and its life history (reproduction, larval cycle and re cruitment phase) has been relatively well described in both controlled environments (Fabioux et al 2005, Enriquez-Diaz et al 2009, Rico-Villa et al 2010) and coastal tidal ecosystems (Dutertre et al 2010, Thomas et al 2016, Bernard et al 2016. Fewer studies have been conducted in nanotidal environments such as Mediterranean lagoons (Tagliapietra & Ghirardini 2006).…”

Evidence that rising coastal seawater temperatures increase reproductive output of the invasive gastropod Crepidula fornicata

“…A pronounced positive effect of water warming on the reproduction of another invasive species, Crassostrea gigas (feral oysters), has previously been documented , Dutertre et al 2010 for Bourgneuf Bay. It thus seems logical to investigate the same possibility for Crepi dula fornicata.…”

“…Normal C. gigas spawning in Bourgneuf Bay occurs from May to July (Dutertre et al 2009(Dutertre et al , 2010, so the appearance of C. fornicata larvae as early as February would permit the benthic recruitment of this species well in advance of C. gigas (which spawned in The combined effect of both an extended brooding season and increased propagule numbers may be expected to accentuate the proliferation of Crepidula fornicata in Bourgneuf Bay, and by the same token, provide a competitive advantage to this species with respect to the co-occurring Crassostrea gigas.…”

“…Warming of water temperature may increase the success of invasive species by facilitating their geographic spread and by promoting more successful reproduction, larval development, and juvenile recruitment (Stachowicz et al 2002, Thieltges et al 2004, Diederich et al 2005, Dutertre et al 2010. A pronounced positive effect of water warming on the reproduction of another invasive species, Crassostrea gigas (feral oysters), has previously been documented , Dutertre et al 2010 for Bourgneuf Bay.…”