ORCID Profile
0000-0002-8935-3296
Current Organisation
South African Institute for Aquatic Biodiversity
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Publisher: Wiley
Date: 12-01-2017
Publisher: Springer Science and Business Media LLC
Date: 29-11-2019
DOI: 10.1007/S10452-019-09735-Y
Abstract: Predator–prey interaction strengths can be highly context-dependent. In particular, multiple predator effects (MPEs), variations in predator sex and physical habitat characteristics may affect prey consumption rates and thus the persistence of lower trophic groups. Ephemeral wetlands are transient ecosystems in which predatory copepods can be numerically dominant. We examine the interaction strengths of a specialist copepod Paradiaptomus lamellatus towards mosquito prey in the presence of conspecifics using a functional response approach. Further, we examine sex variability in predation rates of P. lamellatus under circadian and surface area variations. Then, we assess the influence of a co-occurring heterospecific predatory copepod, Lovenula raynerae , on total predation rates. We demonstrate MPEs on consumption, with antagonism between conspecific P. lamellatus predatory units evident, irrespective of prey density. Furthermore, we show differences between sexes in interaction strengths, with female P. lamellatus significantly more voracious than males, irrespective of time of day and experimental arena surface area. Predation rates by P. lamellatus were significantly lower than the heterospecific calanoid copepod L. raynerae , whilst heterospecific copepod groups exhibited the greatest predatory impact. Our results provide insights into the predation dynamics by specialist copepods, wherein species density, ersity and sex affect interaction strengths. In turn, this may influence population-level persistence of lower trophic groups under shifting copepod predator composition.
Publisher: Wiley
Date: 26-06-2020
Publisher: Springer Science and Business Media LLC
Date: 20-05-2020
DOI: 10.1038/S41467-020-14624-2
Abstract: Globally, our knowledge on lake fisheries is still limited despite their importance to food security and livelihoods. Here we show that fish catches can respond either positively or negatively to climate and land-use changes, by analyzing time-series data (1970–2014) for 31 lakes across five continents. We find that effects of a climate or land-use driver (e.g., air temperature) on lake environment could be relatively consistent in directions, but consequential changes in a lake-environmental factor (e.g., water temperature) could result in either increases or decreases in fish catch in a given lake. A subsequent correlation analysis indicates that reductions in fish catch was less likely to occur in response to potential climate and land-use changes if a lake is located in a region with greater access to clean water. This finding suggests that adequate investments for water-quality protection and water-use efficiency can provide additional benefits to lake fisheries and food security.
Publisher: Springer Science and Business Media LLC
Date: 02-03-2020
DOI: 10.1007/S10530-020-02220-W
Abstract: Our ability to predict invasions has been hindered by the seemingly idiosyncratic context-dependency of in idual invasions. However, we argue that robust and useful generalisations in invasion science can be made by considering “invasion syndromes” which we define as “a combination of pathways, alien species traits, and characteristics of the recipient ecosystem which collectively result in predictable dynamics and impacts, and that can be managed effectively using specific policy and management actions”. We describe this approach and outline ex les that highlight its utility, including: cacti with clonal fragmentation in arid ecosystems small aquatic organisms introduced through ballast water in harbours large ranid frogs with frequent secondary transfers piscivorous freshwater fishes in connected aquatic ecosystems plant invasions in high-elevation areas tall-statured grasses and tree-feeding insects in forests with suitable hosts. We propose a systematic method for identifying and delimiting invasion syndromes. We argue that invasion syndromes can account for the context-dependency of biological invasions while incorporating insights from comparative studies. Adopting this approach will help to structure thinking, identify transferrable risk assessment and management lessons, and highlight similarities among events that were previously considered disparate invasion phenomena.
Publisher: Wiley
Date: 08-2018
DOI: 10.1002/AQC.2958
Publisher: Elsevier BV
Date: 05-2017
Publisher: Springer International Publishing
Date: 2020
Location: South Africa
Location: Malawi
No related grants have been discovered for Olaf Weyl.