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Livramento F.,Agostinho Neto University | Rangel I.M.,Instituto Nacional Of Investigacao Pesqueira
Toxicon | Year: 2010

The presence of ASP toxins in Luanda Bay, an area 2700 km apart from the closest record of this type of toxicity and with a different hydrographic regime, was studied. Two outbreaks were confirmed by LC/MS/MS with presence of domoic acid and some isomers both, in plankton and in three of the most important bivalve species from the area. Domoic acid levels in the studied bivalves were below the regulatory limits for most countries and the first estimations indicate that they depurated the toxin quickly. It is, therefore, unlikely that any intoxication would have taken place by consumption of these bivalve species. Notwithstanding, the relatively high annual frequency of the blooms together with possibility that other bivalve species could retain this compound more strongly, suggest that this kind of intoxication might pose a significant risk in Angola. © 2009 Elsevier Ltd. All rights reserved.


Grant
Agency: European Commission | Branch: FP7 | Program: CP | Phase: ENV.2013.6.1-1 | Award Amount: 12.17M | Year: 2013

Tropical Atlantic climate recently experienced pronounced shifts of great socio-economic importance. The oceanic changes were largest in the eastern boundary upwelling systems. African countries bordering the Atlantic strongly depend upon their ocean - societal development, fisheries, and tourism. They were strongly affected by these climatic changes and will face important adaptation challenges associated with global warming. Furthermore, these upwelling regions are also of great climatic importance, playing a key role in regulating global climate. Paradoxically, the Tropical Atlantic is a region of key uncertainty in earth-climate system: state-of-the-art climate models exhibit large systematic error, climate change projections are highly uncertain, and it is largely unknown how climate change will impact marine ecosystems. PREFACE aims to address these interconnected issues, and has the following goals: To reduce uncertainties in our knowledge of the functioning of Tropical Atlantic climate. To improve climate prediction and the quantification of climate change impacts in the region. To improve understanding of the cumulative effects of the multiple stressors of climate variability, greenhouse induced climate change, and fisheries on marine ecosystems, and ecosystem services (e.g., fisheries, coastal vulnerability). To assess the socio-economic vulnerabilities and evaluate the resilience of Atlantic African fishing communities to climate-driven ecosystem shifts and global markets. To meet these goals we bring together European and African expertise to combine regional and global scale modelling capabilities, field experiments and observation systems. Our target region includes areas more affected by climate change and by its consequences, European outermost regions, and African countries bordering the Atlantic.


Malauene B.S.,University of Cape Town | Malauene B.S.,Instituto Nacional Of Investigacao Pesqueira | Shillington F.A.,University of Cape Town | Roberts M.J.,Oceans and Coasts Research | Moloney C.L.,University of Cape Town
Deep-Sea Research Part II: Topical Studies in Oceanography | Year: 2014

Direct in-situ observations from a shallow underwater temperature recorder on the continental shelf and from a shipboard oceanographic survey, were combined with MODIS satellite data (sea surface temperature and chlorophyll-. a) to assess the temporal and spatial variability of temperature and chlorophyll-. a in the Mozambique Channel near the coastal town of Angoche, 16°S. Intermittent, relatively cool surface water and elevated chlorophyll-. a signatures were found, indicating upwelling near Angoche over an area between 15°S and 18°S. A 5-year (2002-2007) analysis of temperature (from both in-situ and satellite) revealed two distinct periods: (1) the August-March period with highly variable intermittent "cool water" events and (2) the April-July period with little temperature variability. Generally, periods of cooling occurred at about 2 months intervals, but shorter period occurrences (8-30 days) of cool coastal events were also observed. Two possible forcing mechanisms are discussed: (1) wind derived coastal upwelling (using satellite blended sea surface wind derived from NOAA/NCDC) and (2) the effect of passing transient southward moving eddies (using sea level anomalies from AVISO altimetry). It is suggested that the cool surface, elevated chlorophyll-. a waters are primed and formed by favourable wind-driven Ekman-type coastal upwelling, responding to alongshore northeasterly monsoon winds prevailing between August and March. These waters are then enhanced in chlorophyll-. a and advected further offshore by anti-cyclonic/cyclonic eddy pairs interacting with the shelf. © 2013 Elsevier Ltd.


Kirkman S.P.,Oceans and Coasts Research | Kirkman S.P.,University of Cape Town | Yemane D.,Fisheries Management | Yemane D.,University of Cape Town | And 7 more authors.
ICES Journal of Marine Science | Year: 2013

Kirkman, S. P., Yemane, D., Kathena, J., Mafwila, S. K., Nsiangango, S. E., Samaai, T., Axelsen, B., and Singh, L. 2013. Identifying and characterizing demersal fish biodiversity hotspots in the Benguela Current Large Marine Ecosystem: relevance in the light of global changes. - ICES Journal of Marine Science, 70: 943-954.This study made use of distribution and abundance data of demersal fish and cephalopod species targeted during trawl surveys off Angola, Namibia and the west coast of South Africa, to determine species richness patterns including the location of diversity hotspots in the Benguela Current Large Marine Ecosystem. The reliability of alternative techniques for determining species richness patterns over the study domain, including geostatistical and non-geostatistical interpolation methods and regression type modelling, was tested using a cross-validation method. Generalized additive models were found to be the most effective method and were used to generate horizontal maps of species richness for different periods in each country. Despite changes in community structure that have been documented during the study period and which may be associated with climatic changes, this study showed the presence of consistently predictable hotspot areas over a 20-30-year study period (depending on country). The relationship between species richness and physical/environmental variables was inconsistent between countries, but generally hotspots of species richness were associated with greater depths and cooler bottom temperatures. Range shifts of species associated, for example, with warming of temperatures could conceivably affect the spatio-temporal persistence of hotspots in the long term. © 2013 © 2013 International Council for the Exploration of the Sea. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup. com.


Kirkman S.P.,Branch Oceans and Coasts | Kirkman S.P.,University of Cape Town | Yemane D.,University of Cape Town | Atkinson L.J.,University of Cape Town | And 8 more authors.
Fisheries Oceanography | Year: 2015

Using long-term survey data, changes in demersal faunal communities in the Benguela Current Large Marine Ecosystem were analysed at community and population levels to provide a comparative overview of the occurrence and timing of regime shifts. For South Africa, the timing of a community-level shift observed in the early 1990s, and of a lesser shift observed in the mid-2000s, corresponded well with the results of other studies that showed environmental, community-level or population-level changes at similar times, suggesting that environmental forcing had played a role. Several population-level shifts were detected for Namibia; these and a regime shift in the overall community identified for this country corresponded well to the timing of severe environmental perturbations and an extensive regime shift in the pelagic ecosystem of this area. However, the interpretation of these shifts was confounded by changes in sampling gear; closer scrutiny of the types of species affected and the direction of shifts (increase/decrease) in relation to the timing and nature of sampling gear modifications, revealed that the observed shifts were potentially an artefact of gear changes. This highlighted the importance of accounting for changes in sampling protocols during the analysis and interpretation of long-term data. For Angola, a community level shift in the mid-2000s and population-level changes for a few species (mainly positive), could not have been influenced by gear changes which took place mainly before the onset of the time series under consideration. However, no clear environmental or anthropogenic changes that could have influenced these shifts were obvious. © 2015 John Wiley & Sons Ltd.


Yemane D.,Fisheries Management | Yemane D.,University of Cape Town | Kirkman S.P.,Branch Oceans and Coasts | Kirkman S.P.,University of Cape Town | And 4 more authors.
Reviews in Fish Biology and Fisheries | Year: 2014

Distributional change, expressed as range expansion or contraction, has been observed in many marine populations and related to changes in the environment. The extent of such distributional changes is also expected to increase in response to future climate change. The Benguela Current Large Marine Ecosystem (BCLME) which adjoins the south-western coast of Africa is a global marine hotspot with long-term warming occurring over a large area. The area is also an important centre of marine food production for three countries-South Africa, Namibia and Angola and is considered to be vulnerable to future climate change or increased climate variability. In this study we analysed change in distribution and range size of several demersal fish species in the BCLME over the period 1985-2010, including both commercial and non-commercial fish populations. Some of the observed changes in distribution and range size correspond to what is expected with increased warming whereas others appear to the contrary. Overall the results of the study highlight the complex nature of the response of fish population to climate change. © 2014 Springer International Publishing Switzerland.


Vardaro M.F.,Oregon State University | Bagley P.M.,Aker Solutions | Bailey D.M.,University of Glasgow | Bett B.J.,UK National Oceanography Center | And 10 more authors.
Limnology and Oceanography: Methods | Year: 2013

The DELOS (Deep-ocean Environmental Long-term Observatory System) project is a long-term research program focused on understanding the impacts of oil and gas extraction on deep-sea ecosystems. We have installed two seafloor observation platforms, populated with ROV-serviced sensor modules, at 1400 m water depth in the Southeast Atlantic off the coast of Angola. The 'impact' Near-Field platform is located 50 m from subsea oil production facilities. The 'control' Far-Field platform is 16 km distant from any industry seafloor activity. Each platform includes oceanographic, acoustic, and camera sensor modules. The latter carries two still cameras providing close-up and wide-angle views of the seabed. The Far-Field platform is also equipped with a sediment trap that deploys to 100 m above the seafloor. The instrumented platforms were installed in Feb 2009, and the sensor modules subsequently serviced in Aug 2009, Feb 2010, and Aug 2010. Here, we report on our first experiences of operating the observatories and present some of the first data. The oceanographic data (temperature, salinity, oxygen concentration) and biological observations (demersal fish and benthic invertebrates) suggest that the two study sites have near identical environmental characteristics. We, therefore, believe that these sites are appropriate as control and impact locations for long-term monitoring of potential anthropogenic effects referenced to natural background environmental variation. We suggest that DELOS-type observatories, particularly operated as pairs (or in networks), are a highly effective means of appropriately monitoring deep-water resource exploitation-both hydrocarbon extraction and mineral mining ©2013, by the American Society of Limnology and Oceanography, Inc.


Angelini R.,Federal University of Rio Grande do Norte | Angelini R.,University of Cape Town | Vaz-Velho F.,Instituto Nacional Of Investigacao Pesqueira
Scientia Marina | Year: 2011

Information on the mean trophic level of fishery landings in Angola and the output from a preliminary Ecopath with Ecosim (EwE) model were used to examine the dynamics of the Angolan marine ecosystem. Results were compared with the nearby Namibian and South African ecosystems, which share some of the exploited fish populations. The results show that: (i) The mean trophic level of Angola's fish landings has not decreased over the years; (ii) There are significant correlations between the landings of Angola, Namibia and South Africa; (iii) The ecosystem attributes calculated by the EwE models for the three ecosystems were similar, and the main differences were related to the magnitude of flows and biomass; (iv) The similarity among ecosystem trends for Namibia, South Africa and Angola re-emphasizes the need to continue collaborative regional studies on the fish stocks and their ecosystems. To improve the Angolan model it is necessary to gain a better understanding of plankton dynamics because plankton are essential for Sardinella spp. An expanded analysis of the gut contents of the fish species occupying Angola's coastline is also necessary.


Kirkman S.P.,Branch Oceans and Coasts | Kirkman S.P.,University of Cape Town | Yemane D.,Forestry and Fisheries | Oosthuizen W.H.,Branch Oceans and Coasts | And 5 more authors.
Marine Mammal Science | Year: 2013

A time series of aerial censuses of Cape fur seal colonies, spanning four decades (1972-2009) and three countries (South Africa, Namibia, and Angola), was analyzed to assess spatio-temporal changes in population numbers. A weighted quantile regression approach was used to estimate trends in pup counts that were used as proxies for numbers of older animals at breeding colonies. There was a 74% increase in the number of breeding colonies over the study period, from 23 in 1973 to 40 in 2009. There was also a significant northward shift in the distribution of the breeding population. This was largely attributable to events in the northern part of the population's range coinciding with Namibia, where seal numbers declined at most colonies in the south of Namibia while several new breeding colonies developed in the northern part of Namibia and one in southern Angola. Despite range expansion and the development of new colonies, the overall size of the population in 2009 was similar to that of the early 1990s, according to the pup count models. Potential mechanisms for the observed changes, and their management implications, are discussed. © 2012 by the Society for Marine Mammalogy.


Hoguane A.M.,Eduardo Mondlane University | Green C.L.,Bangor University | Bowers D.G.,Bangor University | Nordez S.,Instituto Nacional Of Investigacao Pesqueira
Remote Sensing Letters | Year: 2012

This article explores the possibility of using digital photography to measure the concentration of suspended sediments in coastal water. Photographs of water colour were taken with a commercially available camera at 21 stations in Maputo Bay, Mozambique, using a short tube with one end immersed in the water to remove surface reflection. Surface water samples were collected at the same time and analysed to determine concentrations of chlorophyll-a and phaeopigments ('total' pigments), coloured dissolved organic matter, and total and mineral suspended sediment (MSS) concentration. The optics of the water in the bay is dominated by MSS, which absorbs 75% or more of the light in the red, green and blue parts of the spectrum. As the concentration of MSS increases, the proportion of blue light in the water leaving signal decreases and the proportion of red light increases. The ratio of red to blue 'counts' measured with the camera correlates well with the MSS concentration (R2 = 0.71). There is a weaker but statistically significant relationship between total pigments and the ratio of blue to green counts. We conclude that digital photography is an effective and inexpensive method of quantifying suspended material in these waters although the relationship proposed is likely to be site specific. © 2012 Taylor & Francis.

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