| Title | South Coast Mooring Cruise on the Algoa Voyage 208, July 2014 |
|---|---|
| Authors |
Oceans and Coastal Research |
| Publisher | Department of Forestry, Fisheries and the Environment (2017) |
| Contributors |
Contact Person: Marcel van den Berg |
| Abstract | The South Coast Mooring Cruise was conducted on the Algoa Voyage 208, 9 to 24 July 2014. Two ADCP current moorings and a thermistor chain were deployed along the Cape Point Monitoring line. Cape Recife ADCP current mooring was recovered. Four ADCP current moorings were recovered and serviced in Algoa Bay. Port St. Johns ADCP current mooring was recovered. Port St. Johns Conductivity, Temperature, Depth (CTD)/bongo survey lines were completed. SVP drifters in the Agulhas Current core were deployed. ALEX real-time surface buoy and current meter mooring of Port Edward were deployed.The South Coast Mooring Cruise had two scientific objectives: (1) Service, maintain and extend the in situ operational oceanography network currently deployed around South Africa and (2) to investigate the dynamics of the Port St Johns eddy and biological implications. Between 1988 and 2011, environmental and plankton sampling was conducted every summer along the South Coast during the annual pelagic spawner biomass surveys. Data collected during these cruises has provided valuable insight into environmental change in this region. There has been significant decline in copepod biomass on both the western and central Agulhas Bank over the past two decades, as well as a decline in the proportion of the large dominant species Calanus agulhensis, resulting in a shift towards a smaller copepod-dominated community. These changes are thought to have been largely driven by predation by planktivorous fish, which have increased in biomass since the mid-1990s, but increasing sea temperatures have also played a role. It is vital that we continue to monitor the environment and plakton community in key areas off the South Coast to extend our time-monitor series of data and to gain further insight into the possible effects of climate change and variability on this important Agulhas Bank shelf system, which straddles both the Benguela Current and Agulhas Current Large Marine Ecosystems. Monitoring lines off Walker Bay, Mossel Bay and Port Alfred have been selected to represent the western, central and eastern Agulhas Bank respectively. Monitoring in these areas will detect variability in important oceanographic features, such as the cold ridge and divergent upwelling, and will also span key spawning areas of pelagic fish. The Algoa Bay and Port St John monitoring line has been added to the south coast mooring cruises during 2013 and these long term lines will be completed to add to the above mentioned lines. |
| Data | |
| Temporal extent | 09 Jul 2014 – 24 Jul 2014 |
| Geographic extent |
North: -30.0 |
| Keywords | Agulhas Bank, Agulhas Current, Algoa, Algoa 208, Benguela Current, Calanus agulhensis, copepod biomass, cruise report, Mossel Bay, pelagic spawner biomass, planktivorous fish, Port Alfred, Port St Johns, Port St Johns eddy, sailing orders, South Coast Mooring Cruise, Walker Bay |