Biodiversity of Kelp Forests and Coralline Algae Habitats in Southwestern Greenland

All marine communities in Greenland are experiencing rapid environmental change, and to understand the effects on those structured by seaweeds, baseline records are vital. The kelp and coralline algae habitats along Greenland’s coastlines are rarely studied, and we fill this knowledge gap for the area around Nuuk, west Greenland. Using subtidal swath surveys, photo-quadrats, and grab samples, we characterised the diversity of floral and faunal assemblages in kelp forests and coralline algae beds. The most abundant herbivore assemblages and the most diverse communities occur in the interstitial habitats of rhodolith beds. In kelp forests, species diversity is higher in epi-benthic (photo-quadrat) and mid-water (swath) surveys. These habitats are not mutually exclusive; Agarum clathratum is prominent in coralline algal habitats, while crustose coralline algae cover the bedrock under kelp holdfasts. Overall, the suite of surveys used capture the diverse communities within kelp forests and coralline algae in Greenland and their differing role in the life history of the inhabitants. Furthermore, coralline algae beds are an important carbonate store, with CaCO3 concentrations ranging from 28.06 to 103.73 g·m−3. Our research sets the baseline for continued investigations and monitoring of these important habitats and their supported fisheries.

What is Pseudopotamilla reniformis (Sabellidae)? Comparisons of populations from Britain, Iceland and Canada with comments on Eudistylia and Schizobranchia

A neotype of Amphitrite Müller (1771) is established and re-described, using material collected in 2001 from near the type locality on the southwest coast of Iceland. We examined material from Iceland, Nova Scotia and Newfoundland, identified as Pseudopotamilla reniformis, showing scissiparity and commonly found in aggregations within kelp holdfasts or amongst encrusting fauna. By contrast, scissiparity has not been seen in a population recorded as P. reniformis from Wales (broadcast spawning is presumed, Chughtai & Knight-Jones 1988), which bores into limestone and that the present analysis shows to belong to a different species from P. reniformis. Sabella oculata Krøyer (1856, Norway) is a junior synonym of P. reniformis. Sabella aspersa Krøyer (1856, Greenland) and Sabella saxicava (Quatrefages, 1866, France) are re-instated and re-described in Pseudopotamilla. Pseudopotamilla saxicava (= Potamilla ehlersi Gravier, 1906) has a widespread distribution from Britain to the Arabian Gulf, Pseudopotamilla aspersa is found in Greenland and the distribution of P. reniformis is reduced to Iceland, northern Norway, Nova Scotia and Newfoundland. The genera Eudistylia Bush and Schizobranchia Bush are discussed in relation to Pseudopotamilla.

Diversity and depth-related patterns of mobile invertebrates associated with kelp forests

It is remarkable that although the importance of depth is firmly rooted in the discipline of marine ecology, so little is understood about depth-related patterns of invertebrates in kelp forests, particularly in temperate Australia. We tested for the existence of broad scale patterns in depth-related diversity and abundance of mobile invertebrates in kelp holdfasts (Ecklonia radiata) across several spatial scales along 500 km of coastline. There was a greater abundance and richness of common taxa in holdfasts from shallow relative to deep waters. Strikingly, a disproportionately large percentage (60%) of species was unique to holdfasts from shallow reefs, suggesting that shallow environments create conditions that facilitate a rich biodiversity of invertebrate fauna. We conclude that depth-related variation in kelp forests may not be completely idiosyncratic, and coherent research programs of a broader scale and scope may unify subsets of fragmented knowledge that previously provided little insight into general depth-related patterns of invertebrate assemblages.