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In recent decades, recruitment of young-of-year lobsters to benthic nursery habitats in the Gulf of Maine was regionally synchronized and exhibited correlative links with changes in the abundance of the copepod Calanus finmarchicus, a foundational zooplankton species of the pelagic food web. The spatial scale at which recruitment dynamics were correlated indicated that recruitment processes were not as strongly coupled to trends in spawner abundance as might be expected, but, rather, were influenced by common, ecosystem-scale processes. Here we explored how local- and basin-scale zooplankton dynamics and oceanographic indicators in the Gulf of Maine correlated with lobster settlement indices and each other since the late 1980s. Our analysis indicates that lobster settlement trends in southwestern Gulf of Maine study areas, from Midcoast Maine to Cape Cod Bay, tend to be significantly correlated with basin-wide C. finmarchicus dynamics and the composition of waters entering the Gulf of Maine through the Northeast Channel. In contrast, lobster settlement in the northeastern Gulf, from Penobscot Bay to the Bay of Fundy, tended to correlate more strongly to C. finmarchicus variability in the Bay of Fundy region, which was distinct in earlier years but converged with the broader basin-scale processes in the latter years. Our results are consistent with the hypothesis that the combined effect of climate-related declines in abundance and phenological shifts of C. finmarchicus have contributed to declines in lobster settlement over the past decade, and justify further research into the mechanisms of this interaction. These changes also align with the weakening influence of cold Labrador Slope Water and strengthening effects of warm Gulf Stream waters that precipitated an ecosystem-wide regime shift in the Gulf of Maine over the past decade and may have greater implications for lobster recruitment than previously suspected.
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Range expansion of the lady crab Ovalipes ocellatus Herbst, 1799 (Decapoda: Brachyura: Portunidae) due to ocean warming
Abstract Ocean warming caused by global climate change is driving range expansions and shifts in marine species. The lady crab Ovalipes ocellatus (Herbst, 1799) is generally found south of Cape Cod, Massachusetts, USA with a disjunct population in the southern Gulf of St. Lawrence, Canada, but absent in the Gulf of Maine and Bay of Fundy. Here we present trawl survey data, recent crowd-sourced observations, and temperature data that suggest a range expansion of O. ocellatus north of Cape Cod into the Gulf of Maine and Bay of Fundy after a marine heat wave in 2012. Crowd-sourced observations of lady crabs increased in the Gulf of Maine at the same time that abundances surged after 2000. In the Gulf of Maine, O. ocellatus was found as far north as Freeport, Maine (43°48′17.136″N, 70°6′30.9594″W) and in the Bay of Fundy as far north as Alma, New Brunswick, Canada (45°36′ 13.6794″N, 64°56′29.184″W). We also extend the southern limit of O. ocellatus to St. Augustine, Florida, USA (29°42′9.432″N, 81°13′56.028″ W). The recent observations of O. ocellatus in the northwestern Atlantic and higher abundances combined with continued warming in this area may signal a permanent expansion of this species. If so, a key goal for ecologists and managers will be to understand the effects of O. ocellatus on food webs and fisheries in the Gulf of Maine and Bay of Fundy.
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- Award ID(s):
- 2224608
- PAR ID:
- 10579813
- Publisher / Repository:
- Oxford University Press
- Date Published:
- Journal Name:
- Journal of Crustacean Biology
- Volume:
- 45
- Issue:
- 1
- ISSN:
- 0278-0372
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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