Survival of early life history stages of Arctic kelps (Kongsfjorden,Svalbard) under multifactorial global change scenarios

• Published in: Polar Biology
• Main Authors: Zacher, Katharina, Bernard, Miriam, Bartsch, Inka, Wiencke, Christian
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: SPRINGER 2016
• Subjects: Arctic; Global warming; Kongsfjord*; Kongsfjorden; Polar Biology; Svalbard
• Online Access: https://epic.awi.de/id/eprint/39995/; https://hdl.handle.net/10013/epic.47539

Kelps (brown algae of the order Laminariales) build highly complex and productive underwater forests and possess microscopic and macroscopic life stages. The microscopic stages (spores, gametophytes, juvenile sporophytes) are usually more sensitive to environmental stressors and may form a bottle-neck for the survival of the population. Future Arctic kelp forests will be especially affected by elevated temperatures and increased sedimentation. Knowledge on grazer impact is still rudimentary. In order to investigate how global change in interaction with grazing may shape future Arctic kelp systems we performed laboratory experiments (2 x 3 x 2 factorial design) on early life stages of the kelps Alaria esculenta, Laminaria digitata and Saccharina latissima from Arctic Kongsfjorden (Svalbard). Spores were exposed to ambient and elevated summer temperatures in combination with 3 levels of sediment and 2 levels of grazing by the limpet Margarites helicinus. The germination and formation of juvenile sporophytes was strongly inhibited in all species with increasing sediment cover, clearly showing the strongest negative effect on sporophyte development of all tested variables. Grazers interacted with temperature and sedimentation affecting kelps in a species-specific way. They had a strong impact on the number of developing sporophytes partially counteracting the negative impact of sedimentation. We conclude that the structure of kelp communities can be shaped by abiotic and biotic variables acting on early developmental stages and that global warming has the potential to alter the strengths and direction of these effects, which may lead to future shifts in community structure.