Factors influencing hydroids (Cnidaria: Hydrozoa) biodiversity and distribution in Arctic kelp forest

• Published in: Journal of the Marine Biological Association of the United Kingdom
• Main Authors: Ronowicz, Marta, Wlodarska-Kowalczuk, Maria, Kuklinski, Piotr
• Format: Article in Journal/Newspaper
• Language: English
• Published: Cambridge University Press (CUP) 2008
• Subjects: Aquatic Science; Arctic; Holdfast; Hornsund; Iceberg*; Spitsbergen
• Online Access: http://dx.doi.org/10.1017/s0025315408001495; https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0025315408001495

The biodiversity and distribution patterns of epiphytic hydroids were studied in kelp forests (composed of Laminaria digitata, Saccharina latissima and Alaria esculenta ) located in an Arctic glaciated fiord (Hornsund, west Spitsbergen). In total, twenty-eight species were found colonizing algae, stones connected to holdfast, and overgrowing the surface of other animals associated with kelps. The characteristics of the algal host (e.g. algae species, age, rhizoid volume or biomass) did not show any effect upon hydroid species richness or species composition. High hydroid biodiversity was strongly dependent on microsubstrate heterogeneity. The highest biodiversity as well as frequency of hydroid occurrence were noted at a site located furthest from the glacier and characterized by the lowest sediment concentration and sedimentation rate. Sexual reproduction also seemed to be inhibited by glacier-derived disturbance. Of ten fertile species found at the ‘clearest’ site only two were fertile at sites under the strong influence of such perturbations. Potential physical drivers of species occurrence were linked to the activity of tidal glaciers, particularly to high loads of mineral sedimentation and iceberg scouring.