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St. Andrews, Canada

Konar B.,University of Alaska Fairbanks | Iken K.,University of Alaska Fairbanks | Cruz-Motta J.J.,Simon Bolivar University of Venezuela | Benedetti-Cecchi L.,University of Pisa | And 12 more authors.
PLoS ONE | Year: 2010

Latitudinal gradients in species abundance and diversity have been postulated for nearshore taxa but few analyses have been done over sufficiently broad geographic scales incorporating various nearshore depth strata to empirically test these gradients. Typically, gradients are based on literature reviews and species lists and have focused on alpha diversity across the entire nearshore zone. No studies have used a standardized protocol in the field to examine species density among sites across a large spatial scale while also focusing on particular depth strata. The present research used field collected samples in the northern hemisphere to explore the relationships between macroalgal species density and biomass along intertidal heights and subtidal depths and latitude. Results indicated no overall correlations between either estimates of species density or biomass with latitude, although the highest numbers of both were found at mid-latitudes. However, when strata were examined separately, significant positive correlations were found for both species numbers and biomass at particular strata, namely the intertidal ones. While the data presented in this paper have some limitations, we show that latitudinal macroalgal trends in species density and biomass do exist for some strata in the northern hemisphere with more taxa and biomass at higher latitudes. © 2010 Konar et al.

The recent collection (2009) of an American talon crab, Euchirograpsus americanus A. Milne- Edwards, 1880, in the Bay of Fundy, Canada has expanded the known distribution of this enigmatic plagusiid crab species typically found in subtropical and tropical waters of the Gulf of Mexico, Caribbean, and Carolinas. Although historical records are limited, they document a northward range expansion of the species with occurrences off North Carolina in 1962, Delaware in 1979, and further to New Jersey in 1981, which would discount these northerly records as independent, accidental introductions. The present exclusive record of the talon crab in Canadian waters is also from the shallowest (6.3 m) and coldest waters (8.3°C) that the species has thus far been documented in. The literature, until now, indicated an affinity for sandy or rocky bottom between 31 and 510 m depth at temperatures of 11-24°C. While establishment of the species in the region remains uncertain, the present record is perhaps indicative of large-scale processes, such as climate change, that are altering species distributions. © Koninklijke Brill NV, Leiden, 2016.

Mccusker M.R.,University of Toronto | Denti D.,Dalhousie University | Van Guelpen L.,Atlantic Reference Center | Kenchington E.,Bedford Institute of Oceanography | Bentzen P.,Dalhousie University
Molecular Ecology Resources | Year: 2013

Marine fishes from the northwest Atlantic Ocean were analysed to determine whether barcoding was effective at identifying species. Our data included 177 species, 136 genera, 81 families and 28 orders. Overall, 88% of nominal species formed monophyletic clusters based on >500 bp of the CO1 region, and the average bootstrap value for these species was 98%. Although clearly effective, the percentage of species that were distinguishable with barcoding based on the criterion of reciprocal monophyletic clusters was slightly lower than has been documented in other studies of marine fishes. Eelpouts, sculpins and rocklings proved to be among the most challenging groups for barcoding, although we suspect that difficult identifications based on traditional (morphology based) taxonomy played a role. Within several taxa, speciation may have occurred too recently for barcoding to be effective (e.g. within Sebastes, Thunnus and Ammodytes) or the designation of distinct species may have been erroneous (e.g. within Antimora and Macrourus). Results were consistent with previous work recognizing particularly high levels of divergence within certain taxa, some of which have been recognized as distinct species (e.g. Osmerus mordax and Osmerus dentex; and Liparis gibbus and Liparis bathyarcticus), and some of which have not (e.g. within Halargyreus johnsonii and within Mallotus villosus). The results from this study suggest that morphology-based identification and taxonomy can be challenging in marine fishes, even within a region as well characterized as Atlantic Canada. Barcoding proved to be a very useful tool for species identification that will likely find a wide range of applications, including the fisheries trade, studies of range expansion, ecological analyses and population assessments. © 2012 Blackwell Publishing Ltd.

Halliday R.G.,Northwest Atlantic Fisheries Center | Van Guelpen L.,Atlantic Reference Center | Themelis D.E.,Northwest Atlantic Fisheries Center
Journal of Northwest Atlantic Fishery Science | Year: 2012

The demersal fish fauna at 900-1800 m depths off Nova Scotia, Canada, is described using data from exploratory bottom trawl surveys conducted in November 1994 and March 1995 by a commercial fishing trawler. Approximately 25 metric tons (39 000 specimens) of demersal fish belonging to at least 82 species were caught, 30% of which had not previously been recorded from the area. However, more than half the catch consisted of the two species Centroscyllium fabricii (black dogfish) and Coryphaenoides rupestris (roundnose grenadier). Catches were higher in the shallower depth strata fished and cluster analysis showed that depth was the primary factor determining species composition of catches. It is suspected, however, that the vessel fished less effectively at depths greater than about 1500 m, contributing to the reduction in catch quantities at these depths. The importance in catches of large bodied species, particularly Chimaeriformes and sharks, contrasts with results from surveys in adjacent areas. This likely reflects the greater fishing power of the vessel/gear used in present surveys rather than real differences in faunal composition. Catches of mesopelagic species during these surveys, and during an earlier deepwater trawling survey in this area, are also described. © Her Majesty the Queen in right of Canada, 2012.

Coulson M.W.,Dalhousie University | Coulson M.W.,Marine Scotland - Marine Laboratory | Denti D.,Dalhousie University | Van Guelpen L.,Atlantic Reference Center | And 3 more authors.
Molecular Ecology Resources | Year: 2011

DNA-based identifications have been employed across broad taxonomic ranges and provide an especially useful tool in cases where external identification may be problematic. This study explored the utility of DNA barcoding in resolving skate species found in Atlantic Canadian waters. Most species were clearly resolved, expanding the utility for such identification on a taxonomically problematic group. Notably, one genus (Amblyraja) contained three of four species whose distributions do not overlap that could not be readily identified with this method. On the other hand, two common and partially sympatric species (Little and Winter skates) were readily identifiable. There were several instances of inconsistency between the voucher identification and the DNA sequence data. In some cases, these were at the intrageneric level among species acknowledged to be prone to misidentification. However, several instances of intergeneric discrepancies were also identified, suggesting either evidence of past introgressive hybridization or misidentification of vouchered specimens across broader taxonomic ranges. Such occurrences highlight the importance of retaining vouchered specimens for subsequent re-examination in the light of conflicting DNA evidence. © 2011 Blackwell Publishing Ltd.

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