Effects of detached seaweed and predation on structure and function of polar soft-bottom communities

• Main Author: Díaz Aguirre, María José
• Other Authors: Molis, Markus, Brey, Thomas, Buschbaum, Christian
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: Universität Bremen 2021
• Subjects: Seaweed; Svalbard; Antarctica; Predation; 570; 570 Life sciences; biology; ddc:570; Arctic; Antarc*; Climate change; Sea ice
• Online Access: https://media.suub.uni-bremen.de/handle/elib/5413; https://doi.org/10.26092/elib/1155; https://nbn-resolving.org/urn:nbn:de:gbv:46-elib54138

Polar regions are projected to experience faster and stronger impacts of climate change than the rest of the planet. It is crucial to investigate how climate change drivers may affect polar ecosystems, potentially causing pressures on biodiversity and ecosystem functioning. Specifically, seaweed is considered the primary beneficiaries of the loss of sea ice in polar seas, as some species have increased in bathymetric extent, density and biomass. However, the loss of protective sea ice and increased storm frequency has increased detached seaweed in polar coastal systems. Thus, detached seaweed could represent a connecting vector between rocky and sedimentary habitats in polar regions. Nevertheless, research on the effects of detached seaweed on benthic communities is still limited. Some studies suggest that detached seaweed may provide a food supplement, modify biotic interactions and disturb the benthos by mechanical action on the sedimentary substrate. This thesis aims to investigate the mechanisms by which biotic drivers modify the structure and functioning of coastal sedimentary communities at the poles. In Publication I, I investigated the effects of detached seaweed on the structural and functional traits of species assemblages in soft-bottom intertidal habitats. For this, manipulative experiments based on simulation of detached seaweed patches were conducted for comparative purposes between intertidal sites in the Arctic. I found that patches with seaweed compared to unmanipulated areas reduced the abundance of individuals at both sites and the biomass at one of the intertidal sites. In addition, detached seaweed strongly modified the structure and functioning of the soft-bottom species assemblages at both intertidal sites. Thus, I suggest that the detected effects are possibly the result of seaweed-driven changes in environmental conditions and physical disturbances as underlying processes. Publication II assessed the magnitude and direction of the effects of predation on the diversity and structure of ...