Mesopelagic fish communities of the tropical North Atlantic: Spatial and temporal patterns in composition and structure
The tropical North Atlantic is a region affected by pronounced natural climate variability on multiple spatio-temporal scales, in interplay with environmental effects due to anthropogenic warming. In its eastern part, an oxygen minimum zone (OMZ) is expanding, while in addition, intensive commercial...
| Published in: | Journal of Marine Systems |
|---|---|
| Main Author: | |
| Other Authors: | , |
| Format: | Doctoral or Postdoctoral Thesis |
| Language: | English |
| Published: |
Staats- und Universitätsbibliothek Hamburg Carl von Ossietzky
2022
|
| Subjects: | |
| Online Access: | http://nbn-resolving.de/urn:nbn:de:gbv:18-ediss-101216 https://ediss.sub.uni-hamburg.de/handle/ediss/9697 |
| Summary: | The tropical North Atlantic is a region affected by pronounced natural climate variability on multiple spatio-temporal scales, in interplay with environmental effects due to anthropogenic warming. In its eastern part, an oxygen minimum zone (OMZ) is expanding, while in addition, intensive commercial fishing effort on tuna and small pelagic fish species such as Sardinella spp. occurs; with potential consequences for the structure of pelagic communities and food webs. To be able to assess and monitor these changes, one essential aspect is to increase our current knowledge on mesopelagic fish communities and their functional ecology under different environments. The mesopelagic zone hosts huge biomass of mesopelagic fishes that vertically migrate and interact in the food web with other micronekton organisms, and, thereby, contribute importantly to global marine trophic and biogeochemical cycles. Global large-scale studies demonstrated regional variation in daytime main sound scattering layer (SSL) related to regional environmental characteristics. The accompanying regional variation in the vertical mesopelagic fish community structure and its relative contribution to ecological functioning remain, however, poorly investigated. I conducted the present thesis as part of the EU FP7-Environment project Enhancing Prediction of tropical Atlantic Climate and its Impacts (PREFACE), which aimed to improve our understanding of the functioning of the tropical Atlantic climate, its predictability, and, as part of Work Package 12 (‚Environmental and anthropogenic pressures on pelagic ecosystems and fisheries’), its impacts on pelagic ecosystems and fisheries. Within this framework, we conducted a comprehensive study on abundances, biomass, vertical distribution patterns, size distributions and community and trophic structure of mesopelagic fishes and other micronekton organisms, which were collected during two surveys in 2014 (WH375) and 2015 (WH383) in the eastern North Atlantic. Additional data included in this thesis in ... |
|---|