Nephtheidae soft corals are a common component of benthic ecosystems in the Northwest (NW) Atlantic and in the Arctic, but little is known about their functional roles. Here we investigated their role as habitat for basket stars (Ophiuroidea). By examining over 4500 soft coral colonies of Drifa glomerata, Duva florida, Gersemia spp., and Pseudodrifa racemosa collected during trawl surveys in the regions of Newfoundland, Labrador and West Baffin Bay, we show that Nephtheidae soft corals are habitat for juvenile Gorgonocephalus sp. basket stars. Juvenile Gorgonocephalus sp. were found on all soft corals species, but Drifa glomerata was the soft coral species with the highest occurrence of associated juvenile basket stars (32%), with a maximum of 111 basket stars found on a single 4.8 cm tall (contracted state) colony. Individual basket star disc diameter did not change with colony height, but it varied with season for individuals found on D. glomerata. On the other hand, colony height was positively related with maximum disc diameter (D. glomerata), and presence and number of basket stars on a colony (D. glomerata and D. florida). One very young ophiuroid was found within one polyp of a D. florida colony collected in July. We also examined bottom trawl survey data from 2011 to 2017 from Newfoundland to Baffin Bay, and other locations in the Eastern Canadian Arctic and found that for our largest database, 45% of trawl sets that contained basket stars also contained corals, of which 67% were Nephtheidae soft corals. In this study we show that all four Nephtheidae soft coral taxa studied act as habitat for juvenile basket stars, which are conspicuous components of benthic communities in cold-water environments. Soft corals are commonly exposed and vulnerable to bottom fishing gear in the North Atlantic. We urge future studies evaluating the nature of this relationship, the potential role of soft corals as nurseries, and the potential degree of dependency/preference between basket stars and soft corals in relation to other organisms.

Long-term studies provide an effective way to assess the ecological impacts of decades-long environmental change in Arctic coastal benthic environments but are undertaken rarely in the Canadian Arctic. In light of this, historical datasets can be compared with modern samples to examine temporal differences in benthic community structure. Frobisher Bay, Nunavut provides a unique opportunity to use a historical census to examine the impacts that long-term environmental change have had on the marine benthos. Between 1967-1976 and in 2016, infaunal samples were collected in inner Frobisher Bay and were compared to determine how the molluscan assemblages have changed between the two time periods. Molluscan assemblages in two regions of inner Frobisher Bay (Iqaluit and Cairn Island) were examined to minimize sampling discrepancies between the two time periods. A long-term increase in mean annual air temperature and a decline in the length of the ice cover season were observed. Both regions exhibited some change in sediment composition and quality and in molluscan assemblage between the two time periods and species diversity indices also indicated some change between time periods. Both the 1967-1976 and 2016 molluscan datasets provide a baseline for future long-term studies in a changing Arctic.

the body length–water depth distribution of urophycis tenuis white hake (pisces, gadidae) in the southern gulf of st lawrence (1971–1975, 1981–1985, 1991–1995 and 2001–2002) and cabot strait (1994–1997) was examined. contrary to expectation, linear regression analyses indicated 13 of 17 years had negative slopes with larger fish being found in shallower water. length–depth relationships were statistically significant for five of 17 years (negative slopes: 1971, 1972, 1975, 1981; positive slope: 2002). regression slopes generally increased from 1971 to 2002 indicating the length–depth relationship changed from negative in the early 1970s and 1980s, to negative and positive in the early 1990s, and finally to positive in 2001–2002. in the cabot strait, a significant positive relationship was observed for fish length and water depth indicating large u. tenuis generally occurred in deeper water. we propose that slopes of the length–depth relationship became positive in the 1990s and early 2000s due to the loss of large u. tenuis taken in a seasonal fishery in the southern gulf of st lawrence that targeted highly aggregated spawning and post-spawning shoals of fish in shallow water during summer.

Benthic communities may be significantly impacted by long-term change as a result of anthropogenic or natural stressors. Arctic coastal regions are particularly at risk as seasonal sea ice retreats and previously ice covered regions open. Characterizing marine faunal biodiversity in Arctic regions through predictive habitat mapping is a crucial step towards protecting sensitive Arctic marine ecosystems. Benthic habitat maps provide a snapshot of the existing biological and physical environment while also providing a baseline of knowledge for long-term monitoring. Resampling of historical sites in Frobisher Bay, a large macro-tidal bay in southern Baffin Island, offers a unique opportunity to study temporal and spatial change in benthic communities. Benthic infaunal samples were initially collected at twelve long-term ecology (LTE) stations using a grab sampler in inner Frobisher Bay from 1967-1976, providing seasonal and inter-annual benthic infaunal sample data for this region. In 2015 and 2016, the same LTE stations plus an additional eighteen stations were sampled nearby to a maximum water depth of 100 metres using a grab sampler, box core, and underwater towed video camera system. Benthic faunal samples and sediment samples collected for grain size analysis will be used to ground-truth multibeam bathymetry and backscatter data acquired between 2012 and 2016. Habitat maps produced from infaunal sample data will offer a visual depiction of current spatial community assemblages and allow for an assessment of spatial change based on historical infaunal community composition. This analysis will provide context for assessing temporal change in benthic communities in Frobisher Bay. Polychaetous annelids were the dominant taxa observed at all stations sampled from 1967-1976. Other dominant taxa observed at stations near Iqaluit included oligochaetes, bivalves, and gastropods. Amphipods, ostracods and priapulids were observed at only a few of these stations in high densities. Ostracods were the second most dominant taxa at stations located to the south-east of Iqaluit. Amphipods, bivalves, cumaceans, pycnogonids, and tanaids varied among stations as the third most dominant taxon. Polychaetous annelids were dominant in the sorted 2016 benthic samples with amphipods, bivalves, gastropods, and ophiuroid echinoderms also present at all stations. Some stations near Iqaluit indicated the presence of isopods and ostracods while samples collected to the southeast of Iqaluit indicate the presence of ostracods, pycnogonids, shrimp, and bryozoan fragments. Towed video transects have been analyzed at four LTE stations. Two stations were dominated by tubiculous suspension-feeding polychaetes and ophiuroid echinoderms, however, different ophiuroid species were observed at each of these stations. One station was dominated by a red leafy macroalgae and ophiuroids and another station was dominated by a brown mat over the sediment along with the macroalgae Agarum sp. and Laminaria sp. Community structure analysis performed on the historical and new sample data will evaluate the extent of temporal change of benthic communities in inner Frobisher Bay.