![]() These observations provide information that can potentially be used to forecast longer-term impacts of such changes into the future, which is essential for management and conservation of marine species ( Ruth & Berghahn, 1989 Pinsky et al., 2013 Wahle & Carloni, 2017). Changes in abundances and the size or reproductive structure of species’ populations following such events, as well as overall shifts in community specific composition, illustrate which ecological changes impact particular species and how ( Ruth & Berghahn, 1989 Palumbi & Pinsky, 2014 Bertness et al., 1992). When observational periods coincide with particularly disruptive events, for example natural disasters ( Sato & Chiba, 2016), the introduction of new invasive species ( Delaney et al., 2008), or climate-driven shifts in oceanographic regimes ( Mills et al., 2013 Pinsky et al., 2013), the impacts of such events on the studied species can be illuminating. Such monitoring can provide essential information about the life history and demography of the species of interest ( Hoskin et al., 2011), its interactions with other species in the same community ( Seitz, Knick & Westphal, 2011), and abiotic or biotic factors influencing recruitment to its populations ( Scrosati & Ellrich, 2016). These observations have implications for recruitment to marine populations in this region.ĭetailed observations over time made on organisms of the same species in one or more selected locations, constituting the same putative ‘population(s)’, is a staple of studies in marine biology and ecology in general ( Bertness et al., 1992 Santos & Simon, 1980 McGaw, Edgell & Kaiser, 2011 Palumbi & Pinsky, 2014). Declines to the monitored crab population in this study may have resulted from this same 2013 event. Populations of other marine species in the Gulf of Maine-Bay of Fundy region within which the Minas Basin is situated have also been reported to have undergone dramatic changes in and after 2013, suggesting the occurrence of some oceanographic event or regime shift in the region. Changes in abundances of other species in the area, particularly predators and prey of green crabs, have also been observed and present possible alternative causative agents that should be investigated. However, potential roles of other factors (e.g., autumn winds, summer temperatures, North Atlantic Oscillation index) could not be ruled out. Crab densities in a given year were best explained by potential settlement during the summer and the maximum sea-surface temperature during March of the same year. ![]() Potential causes of interannual changes to this population were investigated by correlating intertidal densities to 257 monthly environmental variables and performing stepwise multiple regression analyses. From 2014 to 2017 the population partially recovered but remained in an altered state. In 2013 intertidal densities, mean crab sizes, subtidal CPUE, and proportions of crabs mature and reproducing all dramatically decreased to all-time lows, and large crabs virtually disappeared from the population. Intertidal densities, sex and reproductive ratios, juvenile recruitment, subtidal catch-per-unit-effort (CPUE), and sizes of crabs in this population were recorded from 2008 to 2017. This paper reports the results of a ten-year monitoring program of an Atlantic Canadian population of green crabs, Carcinus maenas, in the Minas Basin of the Bay of Fundy. Dramatic decline and limited recovery of a green crab ( Carcinus maenas) population in the Minas Basin, Canada after the summer of 2013. For attribution, the original author(s), title, publication source (PeerJ) and either DOI or URL of the article must be cited. Department of Biological Sciences, University of New Brunswick, Saint John, New Brunswick, Canada DOI 10.7717/peerj.5566 Published Accepted Received Academic Editor Bruno Marino Subject Areas Conservation Biology, Ecology, Marine Biology, Zoology, Climate Change Biology Keywords Demography, Gulf of Maine, Carcinus maenas, Crustacea, Monitoring, Bay of Fundy, Climate change, North Atlantic Oscillation index Copyright © 2018 Quinn Licence This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, reproduction and adaptation in any medium and for any purpose provided that it is properly attributed.
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