Do microplastic loads reflect the population demographics along the southern African coastline?
- Authors: Nel, Holly A , Hean, Jeffrey W , Noundou, Xavier S , Froneman, P William
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/67961 , vital:29174 , https://doi.org/10.1016/j.marpolbul.2016.11.056
- Description: Publisher version , Plastic pollution is a major anthropogenic contaminant effecting the marine environment and is often associated with high human population densities and industrial activities. The microplastic (63 to 5000 μm) burden of beach sediment and surf-zone water was investigated at selected sites along the entire length of the South African coastline. It was predicted that samples collected in areas of high population density, would contain a higher microplastic burden than those along coasts that demonstrate very low population densities. With the exception of water column microplastics within Richard's Bay Harbour (413.3 ± 77.53 particles·m− 3) and Durban Harbour (1200 ± 133.2 particles·m− 3), there were no significant spatial differences in microplastic loads. This supports the theory that harbours act as a source of microplastics for the surrounding marine environment. Additionally, the absence of any spatial variation highlights the possible long range distribution of microplastic pollutants by large scale ocean currents.
- Full Text: false
- Date Issued: 2017
Seasonal population dynamics and energy consumption by waterbirds in a small temperate estuary
- Authors: Hean, Jeffrey W , Craig, Adrian J F K , Richoux, Nicole B
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/456305 , vital:75501 , xlink:href="https://doi.org/10.2989/00306525.2016.1230897"
- Description: Simple measures of population dynamics and energy consumption can provide baseline information on the role of consumers in food webs, particularly for cryptic or highly-mobile species of waterbirds. We provide estimates of the seasonal population dynamics and energy consumption of waterbirds along the Kowie Estuary, South Africa. Ten census counts were conducted every month along the estuary from June 2013 to May 2014. Energy consumption and fresh-matter intake were calculated based on body-mass equations. Piscivorous birds dominated the waterbird assemblage during summer (up to 289 individuals), whereas non-migratory shorebirds were dominant at other times of the year. The total wet mass of prey items ingested by waterbirds ranged from 2.8 kg ha−1 during winter to 8.5 kg ha−1 during summer. The total energy consumption of waterbirds ranged from 12 543 kJ ha−1 during June to 33 104 kJ ha−1 during December. Shannon–Wiener diversity calculations revealed that the Kowie Estuary had a greater diversity of waterbirds than several other South African estuaries, but less diversity than many large European estuaries. Studies that incorporate census counts and energy consumption measures, although rudimentary, may provide valuable information on resource use by waterbirds in estuaries and may benefit conservation management schemes.
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- Date Issued: 2017
Connectivity through allochthony: Reciprocal links between adjacent aquatic and terrestrial ecosystems in South Africa
- Authors: Richoux, Nicole B , Moyo, Sydney , Chari, Lenin D , Bergamino, Leandro , Carassou, Laure , Dalu, Tatenda , Hean, Jeffrey W , Sikutshwa, Likho , Gininda, Simphiwe , Magoro, Mandla L , Perhar, Gurbir , Ni, Felicity , Villet, Martin H , Whitfield, Alan K , Parker, Daniel M , Froneman, P William , Arhonditsis, George , Craig, Adrian J F K
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , report
- Identifier: http://hdl.handle.net/10962/438363 , vital:73454 , ISBN 978-1-4312-0679-7 , https://wrcwebsite.azurewebsites.net/wp-content/uploads/mdocs/2186-1-15.pdf
- Description: An important aspect of the dynamics of nutrients and pollutants in natural systems is captured in the concept of allochthony, founded on the observation that nutrients and energy in a variety of forms are transferred between adjacent habitats, com-munities and ecosystems that are not routinely considered as connected. Different forms of nutrients and energy move across the conceptual boundaries of habitats via organisms’ activities or physical processes such as wind or water currents, and these transfers can represent important food subsidies. Such cross-partition ecolog-ical subsidies can augment the nutritional condition, biomass and biodiversity of communities, particularly where local production (or autochthony) alone may be inadequate to support local food webs. Furthermore, organic subsidies can influ-ence population dynamics, community interactions and ecosystem processes, and can represent dominant flux inputs in ecosystem budgets. Our intention was to ex-plore organic nutrient fluxes in relation to a primarily lotic (i.e. flowing) aquatic sys-tem at the scale of a hydrological catchment.
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- Date Issued: 2015