Effects of anthropogenic stressors on Helgoland’s lobsters (Homarus gammarus)

• Main Author: Leiva, Laura
• Other Authors: Boersma, Maarten, Heubel, Katja, Rohlfs, Marko, Fuchs, Berhard
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: Universität Bremen 2023
• Subjects: Lobster biology; ocean acidification; ocean warming; Noise pollution; Climate Change; 80; ddc:80; Helgoland; European lobster; Homarus gammarus; Ocean acidification
• Online Access: https://media.suub.uni-bremen.de/handle/elib/6900; https://doi.org/10.26092/elib/2221; https://nbn-resolving.org/urn:nbn:de:gbv:46-elib69005

As meroplankton, lobsters make up a great portion of both benthic communities and planktonic fauna in the water column. Furthermore, they represent a mayor food source across the marine food web and a vital source of protein for humans. As an economically important species, lobsters are highly susceptible to anthropogenic stressors (e.g habitat destruction, over-fishing, noise pollution). Moreover, climate change may magnify the impact of human activities on lobsters’ fitness. The collapse of the population of European lobster (Homarus gammarus) around Helgoland constitutes a good example and prompted a large-scale restocking program. Yet, the question arises if recruitment of remaining natural individuals and program released specimens could be stunted by ongoing climate change and human activities. In my thesis I investigate the effect of several anthropogenic stressors that could potentially be affecting the route to recovery of Helgoland’s lobsters. Since monitoring of lobster larvae has not been implemented on the island yet, I performed laboratory and field experiments to evaluate the potential of using light-traps on the island of Helgoland to catch lobster larvae. Developing adequate traps is useful to support research on the European lobster in the wild and conservation efforts. The light traps used white LED lights and successfully trapped lobster larvae in laboratory experiments at different densities of 100 and 10 ind/m3 , and in the field experiment, six traps were deployed weekly throughout lobster larvae hatching season in the months of May to August. Traps were deployed in two different rocky seabed sites, that are adequate habitats for larvae, and at different depths (1, 2, 4, and 6 m). However, no lobster larvae were caught in the field. This may be due to several reasons: (1) low population numbers of lobster larvae, (2) a rapid loss of positive phototactic response of larvae to light or (3) the chosen deployment sites were not appropriate. Future research is needed to construct a specialized ...