Full Text Available
Note: Clicking the button above will open the full text document at the original institutional repository in a new window.
Environmental influences on banana shrimps of the Sofala Bank, Mozambique Channel
The Sofala Bank in the western Mozambique Channel is an essential habitat for shallow-water penaeid shrimps. It supports an important multi-sector and -species fishery, with Fenneropenaeus indicus and Metapenaeus monoceros (banana shrimp) being the two main target species. Over the past decade thi...
Saved in:
| Main Author: | |
|---|---|
| Other Authors: | |
| Format: | Thesis |
| Language: | English |
| Published: |
Department of Biological Sciences
2015
|
| Subjects: | |
| Tags: |
No Tags, Be the first to tag this record!
|
| _version_ | 1867614178943959040 |
|---|---|
| access_status_str | Open Access |
| author | Malauene, Bernardino Sergio |
| author2 | Moloney, Coleen L |
| author_browse | Malauene, Bernardino Sergio Moloney, Coleen L |
| author_facet | Moloney, Coleen L Malauene, Bernardino Sergio |
| author_sort | Malauene, Bernardino Sergio |
| collection | Thesis |
| description | The Sofala Bank in the western Mozambique Channel is an essential habitat for shallow-water penaeid shrimps. It supports an important multi-sector and -species fishery, with Fenneropenaeus indicus and Metapenaeus monoceros (banana shrimp) being the two main target species. Over the past decade this valuable resource has been declining, which has been attributed to environmental changes, but no conclusive evidence has been found. This PhD thesis aims to understand the interactive roles of biophysical processes on recruitment of banana shrimps, par ticularly their larvae on the Sofala Bank. It is hypothesized that shrimp larvae can be advected offshore by passing mesoscale eddies to regions where they are unable to survive and are thus lost. In the absence of both physical and biological observations, a modelling approach is used. A high-resolution, nested, coastal, Regional Ocean Modeling System (ROMS) of the Sofala Bank is developed. In general, the model agrees well with available observations and literature. The ROMS outputs and self-organizing map analysis indicate that the shelf circulation, structure and river plumes are strongly influenced by the highly energetic o_shore eddy activity. A biophysical, individual-based model (IBM) coupled to the ROMS was developed for early life stages of banana shrimps on the Sofala Bank. The IBM uses spawning patterns identified from analyses of both commercial and research survey data. Simulations indicate that shrimp larvae are lost offshore by entrainment in mesoscale eddies at inter- and intra-annual scales and eddies therefore are unlikely to produce a continuous declining in the catch. In contrast, these eddies induce onshore transport of larvae, promoting coastal settlement, compared with periods without eddies. Locations for simulated larval coastal settlement are identified: northern, central and southern. The roles of tides and larval diel vertical migration in influencing simulated larval settlement success was not conclusive; further research considering a selective tidal stream is needed. Simulated larvae were sensitive to low lethal temperature and river plumes. A conceptual model for the Sofala Bank circulation and another for the banana shrimps, early life history dynamics are proposed based on the results of this thesis. |
| format | Thesis |
| id | oai:open.uct.ac.za:11427/15609 |
| institution | University of Cape Town (South Africa) |
| language | eng |
| last_indexed | 2026-06-10T12:47:55.415Z |
| license_str | Not specified — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UCTD — University of Cape Town Open Access Repository |
| publishDate | 2015 |
| publishDateRange | 2015 |
| publishDateSort | 2015 |
| publisher | Department of Biological Sciences |
| publisherStr | Department of Biological Sciences |
| record_format | dspace |
| source_str | UCTD — University of Cape Town Open Access Repository |
| spelling | oai:open.uct.ac.za:11427/15609 Environmental influences on banana shrimps of the Sofala Bank, Mozambique Channel Malauene, Bernardino Sergio Moloney, Coleen L Roberts, Michael J Marsac, Francis Penven, Pierrick Lett, Christophe Biological Sciences Marine Research The Sofala Bank in the western Mozambique Channel is an essential habitat for shallow-water penaeid shrimps. It supports an important multi-sector and -species fishery, with Fenneropenaeus indicus and Metapenaeus monoceros (banana shrimp) being the two main target species. Over the past decade this valuable resource has been declining, which has been attributed to environmental changes, but no conclusive evidence has been found. This PhD thesis aims to understand the interactive roles of biophysical processes on recruitment of banana shrimps, par ticularly their larvae on the Sofala Bank. It is hypothesized that shrimp larvae can be advected offshore by passing mesoscale eddies to regions where they are unable to survive and are thus lost. In the absence of both physical and biological observations, a modelling approach is used. A high-resolution, nested, coastal, Regional Ocean Modeling System (ROMS) of the Sofala Bank is developed. In general, the model agrees well with available observations and literature. The ROMS outputs and self-organizing map analysis indicate that the shelf circulation, structure and river plumes are strongly influenced by the highly energetic o_shore eddy activity. A biophysical, individual-based model (IBM) coupled to the ROMS was developed for early life stages of banana shrimps on the Sofala Bank. The IBM uses spawning patterns identified from analyses of both commercial and research survey data. Simulations indicate that shrimp larvae are lost offshore by entrainment in mesoscale eddies at inter- and intra-annual scales and eddies therefore are unlikely to produce a continuous declining in the catch. In contrast, these eddies induce onshore transport of larvae, promoting coastal settlement, compared with periods without eddies. Locations for simulated larval coastal settlement are identified: northern, central and southern. The roles of tides and larval diel vertical migration in influencing simulated larval settlement success was not conclusive; further research considering a selective tidal stream is needed. Simulated larvae were sensitive to low lethal temperature and river plumes. A conceptual model for the Sofala Bank circulation and another for the banana shrimps, early life history dynamics are proposed based on the results of this thesis. 2015-12-04T19:32:21Z 2015-12-04T19:32:21Z 2015 Doctoral Thesis Doctoral PhD http://hdl.handle.net/11427/15609 eng application/pdf Department of Biological Sciences Faculty of Science University of Cape Town |
| spellingShingle | Biological Sciences Marine Research Malauene, Bernardino Sergio Environmental influences on banana shrimps of the Sofala Bank, Mozambique Channel |
| thesis_degree_str | Doctoral |
| title | Environmental influences on banana shrimps of the Sofala Bank, Mozambique Channel |
| title_full | Environmental influences on banana shrimps of the Sofala Bank, Mozambique Channel |
| title_fullStr | Environmental influences on banana shrimps of the Sofala Bank, Mozambique Channel |
| title_full_unstemmed | Environmental influences on banana shrimps of the Sofala Bank, Mozambique Channel |
| title_short | Environmental influences on banana shrimps of the Sofala Bank, Mozambique Channel |
| title_sort | environmental influences on banana shrimps of the sofala bank mozambique channel |
| topic | Biological Sciences Marine Research |
| url | http://hdl.handle.net/11427/15609 |
| work_keys_str_mv | AT malauenebernardinosergio environmentalinfluencesonbananashrimpsofthesofalabankmozambiquechannel |