Factors affecting biodiversity on hermit crab shells

Abstract

This study explores the abundance, diversity and assemblage structure of epifauna on the shells used by two hermit crab species (Pagurus bernhardus and P. pubescens) in the Arctic (Svalbard and Northern Norway) and investigates the biotic and physical drivers of such patterns. Contrary to our expectations, we found that location (which reflects the variability in environmental conditions and the local species pool of potential colonizers) is a key determinant not only in the cold, ice-scoured, glacierdominated Arctic shallows of Svalbard but also in boreal Norwegian fjords, where other factors were hypothesized to be more important. Depending on region, shell area and identity were of lesser magnitude, with larger and more irregular shells containing more diverse assemblages. Crab host species also played a role (P. pubescens-inhabited shells supported larger number of individuals and higher diversity than those of P. bernhardus) but this effect might be species or region specific. In this study, no effect of crab gender could be detected. The study indicated that epifaunal assemblages of hermit crab shells are influenced by complex set of factors that interact together to different degree at various locations.

Year‐to‐year variability of epifaunal assemblages on a mobile hard substrate—Case study from high latitudes

“…Differences between hermit crab shell replicates (i.e., from sample to sample) were a much higher source of variation than investigated factors which is typical (Balazy et al, ) also in studies on other groups of organisms (Anderson, Diebel, Blom, & Landers, ; Underwood & Chapman, ; Włodarska‐Kowalczuk & Wȩsławski, ). However, high internal variability due to large number of possible hermit crab associates in the studied sites (69 species in Greenland Sea, and 41 in Norwegian Sea; Balazy & Kuklinski, ) should be considered when using pagurids for shallow water monitoring.…”

“…Differences between hermit crab shell replicates (i.e., from sample to sample) were a much higher source of variation than investigated factors which is typical (Balazy et al, 2016) all the shells in this study belonged to one family and genus (within a locality), shell species had a significant influence on epifauna assemblage structure in Spitsbergen, which shows that even small differences in shell surface heterogeneity, measured in millimetres, might influence epifauna settling (Hills & Thomason, 2009;Lapointe & Bourget, 1999;Rodriguez, Ojeda, & Inestrosa, 1993). The smaller the shell size, the randomness effect and competition for space increases as on a small substrate, the first colonist is able to occupy the majority of available space and prevent recruitment of others (McLean, 1983).…”

“…The data were analysed using a two‐factor (1‐Year, 2‐Shell identity) fixed design, conducted separately for Spitsbergen and Northern Norway. Because area of the substrate significantly affects epifaunal diversity and abundance (Balazy et al, ; Conover, ; McGaw, ) gastropod shell area was included as a covariate in all the analyses. The statistical significance of multivariate and univariate variance components was tested using 9,999 permutations of residuals under a reduced model (Anderson & Ter Braak, ).…”

“…Among available studies on inter-annual variability of the benthic systems of the high Arctic, most concern soft bottom communities (Bergmann et al, 2011;Blanchard, 2015;Kędra, Włodarska-Kowalczuk, & Węsławski, 2010;Renaud et al, 2007), and fewer of them were conducted on hard bottom assemblages (but see Beuchel et al, 2006;Beuchel & Gulliksen, 2008). To date, there are no studies dealing with mobile hard substrates (i.e., organisms hard externa, like carapaces of decapod crustaceans or hermit crabs-superfamily Paguroidea; Balazy, Kuklinski, Włodarska-Kowalczuk, Gluchowska, & Barnes, 2016), yet these are an important part of Arctic shallow water marine systems, both in terms of abundance (Balazy et al, 2015;Barnes, Kukliński, & Włodarska-Kowalczuk, 2007;Berge et al, 2009) and the role that they play in increasing local biodiversity (Balazy & Kuklinski, 2013).…”