Evidence for an increasing incidence and severity of Harmful Algal Blooms in the southern Benguela region

Harmful Algal Blooms (HABs) may lead to catastrophic mortality over a range of trophic levels and impact on fisheries, local species' populations, conservation management and the health of both livestock and humans. Consequently, any increase in frequency and / or toxicity of these events is of concern. Recently this concern has been realized, with reported increases in the frequency of HABs from all continents except Antarctica. This reported rise is supported by data from the Benguela coast of western South Africa, where, since 1930, there has been a significant increase in the frequency of HABs and a slight increase in their average severity. There has been a sixfold increase in the number of HABs per decade since the 1960s, with the period 1990-2005 experiencing the greatest number of blooms, as well as the most severe in terms of associated mortality. The recent occurrence of previously unrecorded HAB-causing species in this region may go some way to explaining this trend, and further implies that the increase is unlikely to diminish in the near future

Impacts of a South African coastal golf estate on shrubland bird communities

Golf courses and estates are one form of development threatening coastal vegetation in South Africa's Cape Floristic Region. They occupy substantial tracts of land, fragmenting indigenous vegetation. This study investigates the effects on bird community structure and function of replacing natural Strandveld vegetation with a 170-ha golf estate in which 46 ha of Strandveld vegetation was retained in conditions ranging from pristine to moderately degraded. Bird assemblages of the remaining Strandveld patches in the golf estate were compared with those of an adjacent Strandveld conservation area. Field work was conducted during the birds' breeding season, in October and November 2005. The golf estate was more species rich overall, but many species were uncommon, several were present only as a consequence of the creation of new habitats, and species were not evenly distributed across the remaining Strandveld fragments. Bird diversity and abundance were significantly higher in the adjacent conservation area. It is estimated that more than 8500 individual birds were displaced by construction of the golf estate and four Strandveld species were not represented at all within the estate. Within the estate, species richness rose with increasing Strandveld patch size and the minimum area of continuous pristine vegetation required to maintain the natural species assemblage was estimated at 51 ha. The golf estate was characterized by a high proportion of generalist and granivorous species, but at the cost of reduced numbers of frugivores and nectarivores. Energy flow through the bird communities in the two areas was thus markedly different, and pollination and fruit dispersal potential within the golf estate were reduced substantially. Golf courses and golf estates inevitably will not substitute for the natural habitats they have replaced, but careful design with input from ecological theory can reduce the adverse effects of fragmentation

Temperatures in Excess of Critical Thresholds Threaten Nestling Growth and Survival in A Rapidly-Warming Arid Savanna: A Study of Common Fiscals

Frequency, duration, and intensity of hot-weather events are all predicted to increase with climate warming. Despite this, mechanisms by which temperature increases affect individual fitness and drive population-level changes are poorly understood. We investigated the link between daily maximum air temperature (t max ) and breeding success of Kalahari common fiscals ( Lanius collaris ) in terms of the daily effect on nestling body-mass gain, and the cumulative effect on size and age of fledglings. High t max reduced mass gain of younger, but not older nestlings and average nestling-period t max did not affect fledgling size. Instead, the frequency with which t max exceeded critical thresholds (t crit s) significantly reduced fledging body mass (t crit  = 33°C) and tarsus length (t crit  = 37°C), as well as delaying fledging (t crit  = 35°C). Nest failure risk was 4.2% per day therefore delays reduced fledging probability. Smaller size at fledging often correlates with reduced lifetime fitness and might also underlie documented adult body-size reductions in desert birds in relation to climate warming. Temperature thresholds above which organisms incur fitness costs are probably common, as physiological responses to temperature are non-linear. Understanding the shape of the relationship between temperature and fitness has implications for our ability to predict species’ responses to climate change

Identifying biologically meaningful hot-weather events using threshold temperatures that affect life-history

Increases in the frequency, duration and intensity of heat waves are frequently evoked in climate change predictions. However, there is no universal definition of a heat wave. Recent, intense hot weather events have caused mass mortalities of birds, bats and even humans, making the definition and prediction of heat wave events that have the potential to impact populations of different species an urgent priority. One possible technique for defining biologically meaningful heat waves is to use threshold temperatures (T thresh ) above which known fitness costs are incurred by species of interest. We set out to test the utility of this technique using T thresh values that, when exceeded, affect aspects of the fitness of two focal southern African bird species: the southern pied babbler Turdiodes bicolor (T thresh = 35.5°C) and the common fiscal Lanius collaris (T thresh = 33°C). We used these T thresh values to analyse trends in the frequency, duration and intensity of heat waves of magnitude relevant to the focal species, as well as the annual number of hot days (maximum air temperature > T thresh ), in north-western South Africa between 1961 and 2010. Using this technique, we were able to show that, while all heat wave indices increased during the study period, most rapid increases for both species were in the annual number of hot days and in the maximum intensity (and therefore intensity variance) of biologically meaningful heat waves. Importantly, we also showed that warming trends were not uniform across the study area and that geographical patterns in warming allowed both areas of high risk and potential climate refugia to be identified. We discuss the implications of the trends we found for our focal species, and the utility of the T thresh technique as a conservation tool

Host specificity and co-speciation in avian haemosporidia in the Western Cape, South Africa

Host and pathogen ecology are often closely linked, with evolutionary processes often leading to the development of host specificity traits in some pathogens. Host specificity may range from ‘generalist’, where pathogens infect any available competent host; to ‘specialist’, where pathogens repeatedly infect specific host species or families. Avian malaria ecology in the region remains largely unexplored, despite the presence of vulnerable endemic avian species. We analysed the expression of host specificity in avian haemosporidia, by applying a previously developed host specificity index to lineages isolated from wetland passerines in the Western Cape, South Africa. Parasite lineages were isolated using PCR and identified when possible using matching lineages deposited in GenBank and in MalAvi. Parasitic clades were constructed from phylogenetic trees consisting of Plasmodium and Haemoproteus lineages. Isolated lineages matched some strains of Plasmodium relictum , P. elongatum , Haemoproteus sylvae and H. lanii . Plasmodium lineages infected a wide range of hosts from several avian families in a generalist pattern of infection. Plasmodium spp. also exhibited an infection trend according to host abundance rather than host species. By contrast, Haemoproteus lineages were typically restricted to one or two host species or families, and displayed higher host fidelity than Plasmodium spp. The findings confirm that a range of host specificity traits are exhibited by avian haemosporidia in the region. The traits show the potential to not only impact infection prevalence within specific host species, but also to affect patterns of infection at the community level

Climate Change, Coral Reef Ecosystems, and Management Options for Marine Protected Areas

Marine protected areas (MPAs) provide place-based management of marine ecosystems through various degrees and types of protective actions. Habitats such as coral reefs are especially susceptible to degradation resulting from climate change, as evidenced by mass bleaching events over the past two decades. Marine ecosystems are being altered by direct effects of climate change including ocean warming, ocean acidification, rising sea level, changing circulation patterns, increasing severity of storms, and changing freshwater influxes. As impacts of climate change strengthen they may exacerbate effects of existing stressors and require new or modified management approaches; MPA networks are generally accepted as an improvement over individual MPAs to address multiple threats to the marine environment. While MPA networks are considered a potentially effective management approach for conserving marine biodiversity, they should be established in conjunction with other management strategies, such as fisheries regulations and reductions of nutrients and other forms of land-based pollution. Information about interactions between climate change and more “traditional” stressors is limited. MPA managers are faced with high levels of uncertainty about likely outcomes of management actions because climate change impacts have strong interactions with existing stressors, such as land-based sources of pollution, overfishing and destructive fishing practices, invasive species, and diseases. Management options include ameliorating existing stressors, protecting potentially resilient areas, developing networks of MPAs, and integrating climate change into MPA planning, management, and evaluation

Re-assessment of the conservation status of Malawi's 'Endangered' Yellow-throated Apalis Apalis flavigularis

The forest-associated Yellow-throated Apalis Apalis flavigularis is the only bird endemic to Malawi. The species is confined to three mountain massifs in the south of the country and is classified as globally ‘Endangered’. This study re-evaluates its conservation status by assessing its population size and habitat preferences on Mount Mulanje, where forest patches are threatened by illegal logging and an increasing frequency of uncontrolled fires. These fires also cause a proliferation of invasive plant species, especially the Himalayan yellow raspberry Rubus ellipticus. We surveyed the Yellow-throated Apalis in 41 forest patches during the breeding season. The apalises favoured forest edge habitat, occurring in forest patches as small as 0.01 ha. Their occurrence was positively correlated with the presence of R. ellipticus, although this relationship may be driven primarily by canopy architecture and the existence of an understorey shrub layer. At a conservative estimate, 7,900 Yellow-throated Apalises were calculated to be present in cedar forest habitat alone on Mount Mulanje. Given that the birds occurred in other native forests at the same altitude at densities of 8.6–10.9 birds ha⁻¹, the true population size on Mount Mulanje alone is likely to approach or even exceed IUCN’s most optimistic estimate of the global population (10,000).9 page(s