Genetic variation in Rhipicephalus appendiculatus (Acari: Ixodidae) from Zambia: correlating genetic and ecological variation with Rhipicephalus appendiculatus from eastern and southern Africa.

Based on their ecology, Rhipicephalus appendiculatus ticks from eastern and southern Africa have been divided into three groups. We investigated how two geographic genetically differentiated stocks of R. appendiculatus from the southern and the eastern provinces of Zambia, representing two ecological groups, i.e., southern African and transition groups, respectively, genetically compare to stocks from east Africa (Rwanda) and southern Africa (Zimbabwe and South Africa). The ITS2 and two mitochondrial genes segments, 12s rDNA and COI, were used in the investigations. The ITS2 tree did not show support for differentiation into any groups, while the two mitochondrial genes trees (12s rDNA and COI) showed two genetically differentiated groups: an east African genetic group which included specimens from Rwanda and the plateau area of the eastern province of Zambia, and a southern African genetic group represented by specimens from South Africa, Zimbabwe and specimens collected on the fringes of the eastern province plateau in the Nyimba district of Zambia. This suggests that the two geographically differentiated stocks of the southern and eastern provinces of Zambia might be part of two wider geographic genetically differentiated R. appendiculatus groups that extend beyond Zambia. Stocks of "transition" ecology (eastern province) belong to the east African genetic group and the differences in ecology within this genetic grouping may be due to genetic polymorphism, phenotypic plasticity, and other local factors.     

Prioritising Mangrove Ecosystem Services Results in Spatially Variable Management Priorities

Incorporating the values of the services that ecosystems provide into decision making is becoming increasingly common in nature conservation and resource management policies, both locally and globally. Yet with limited funds for conservation of threatened species and ecosystems there is a desire to identify priority areas where investment efficiently conserves multiple ecosystem services. We mapped four mangrove ecosystems services (coastal protection, fisheries, biodiversity, and carbon storage) across Fiji. Using a cost-effectiveness analysis, we prioritised mangrove areas for each service, where the effectiveness was a function of the benefits provided to the local communities, and the costs were associated with restricting specific uses of mangroves. We demonstrate that, although priority mangrove areas (top 20%) for each service can be managed at relatively low opportunity costs (ranging from 4.5 to 11.3% of overall opportunity costs), prioritising for a single service yields relatively low co-benefits due to limited geographical overlap with priority areas for other services. None-the-less, prioritisation of mangrove areas provides greater overlap of benefits than if sites were selected randomly for most ecosystem services. We discuss deficiencies in the mapping of ecosystems services in data poor regions and how this may impact upon the equity of managing mangroves for particular services across the urban-rural divide in developing countries. Finally we discuss how our maps may aid decision-makers to direct funding for mangrove management from various sources to localities that best meet funding objectives, as well as how this knowledge can aid in creating a national mangrove zoning scheme.     

Variation in body size in the tick complex Rhipicephalus appendiculatus/Rhipicephalus zambeziensis.

We examined the relationship between body size and the phenology of the tick complex Rhipicephalus appendiculatus/Rhipicephalus zambeziensis. These ticks transmit Theileria parva in cattle. In Africa, the body size of R. appendiculatus increases with latitude while the body size of the morphologically similar Rhipicephalus zambeziensis is constant at two different latitudes. A larger body size is necessary once survival becomes a constraint. The most plausible explanation for the smaller R. appendiculatus in equatorial Africa is the cost to produce a larger egg. The consequences of these findings for the introduction of R. appendiculatus in new environments are discussed. New field observations from southern Zambia indicate that R. appendiculatus body size does not vary seasonally as compared to eastern Zambia. This is an additional indication of the presence of a single diapausing population of larger ticks.     

Linkages between coral assemblages and coral proxies of terrestrial exposure along a cross-shelf gradient on the southern Great Barrier Reef

Coral core records, combined with measurements of coral community structure, were used to assess the long-term impact of multiple environmental stressors on reef assemblages along an environmental gradient. Multiple proxies (luminescent lines, Ba/Ca, δ¹⁵N) that reflect different environmental conditions (freshwater discharge, sediment delivery to the nearshore, nutrient availability and transformations) were measured in Porites coral cores collected from nearshore reefs at increasing distance from the intensively agricultural region of Mackay (Queensland, Australia). The corals provide a record (1968–2002) of the frequency and intensity of exposure to terrestrial runoff and fertilizer-derived nitrogen and were used to assess how the present-day coral community composition may have been influenced by flood-related disturbance. Reefs closest to the mainland (5–32 km offshore) were characterized by low hard coral cover (≤10%), with no significant differences among locations. Distinct annual luminescent lines and elevated Ba/Ca values (4.98 ± 0.63 μmol mol⁻¹; mean ± SD) in the most inshore corals (Round Top Island; 5 km offshore) indicated chronic, sub-annual exposure to freshwater and resuspended terrestrial sediment that may have historically prevented reef formation. By contrast, corals from Keswick Island (32 km offshore) indicated episodic, high-magnitude exposure to Pioneer River discharge during extreme flood events (e.g., 1974, 1991), with strongly luminescent lines and substantially enriched coral skeletal δ¹⁵N (12–14‰). The reef assemblages at Keswick and St. Bees islands were categorically different from all other locations, with high fleshy macroalgal cover (80.1 ± 7.2% and 62.7 ± 7.1%, respective mean ± SE) overgrowing dead reef matrix. Coral records from Scawfell Island (51 km offshore) indicated little exposure to Pioneer catchment influence: all locations from Scawfell and further offshore had total hard and soft coral cover comparable to largely undisturbed nearshore to middle shelf reefs of the southern Great Barrier Reef.     

Distribution and phenology of ixodid ticks in southern Zambia

Distribution data for epidemiologically important ticks (Acari: Ixodidae) in the Southern Province of Zambia, one of the main cattle areas of the country, are presented. Boophilus microplus (Canestrini) was not recorded in southern Zambia, whereas Boophilus decoloratus (Koch) is present throughout the area. New distribution patterns for less economically important ixodid ticks are also discussed. Southern Zambia is a transition zone because it is the most northern area in Africa where mixed Rhipicephalus appendiculatus Neumann and Rhipicephalus zambeziensis Walker, Norval & Corwin populations were reported. Although a second generation of adult R. appendiculatus/R. zamnbeziensis was encountered, simulations indicated that this phenomenon is very rare in southern Zambia, mainly because of the colder temperatures during the early dry season and lower rainfall. These simulations were supported by a development trial under experimental conditions. Tick body size measurements showed that southern Zambian ticks are larger than eastern Zambian R. appendiculatus. It is hypothesized that body size is related to diapausing intensity in this species. The epidemiological consequences are that a different approach to control Theileria parva (Theiler) (Piroplasmida: Theileriidae) and other tick-borne diseases is needed in southern Zambia, compared to the one adopted in eastern Zambia.     

The effects of anthrax on endangered African wild dogs (Lycaon pictus)

African wild dogs ( Lycaon pictus ) are large, social canids formerly found throughout sub-Saharan Africa. Wild dogs are now endangered; only six nations hold populations larger than 100 individuals. Considerable evidence suggests that disease plays a central role in the regulation of some wild dog populations. In particular, it has been suggested that epizootics of rabies, canine distemper and anthrax can have strong local effects on wild dog numbers. Resolution of the regulatory importance of these diseases has been hampered by lack of data from wild populations. Here we report on an outbreak of anthrax among wild dogs in the Selous Game Reserve in southern Tanzania, describing clinical signs and diagnosis, measuring mortality, and testing for effects on hunting success and movements. Only one of five packs under study was affected. Immediate mortality was mild, with none of 18 adults (0%) and four of 24 pups (17%) dying. Mortality was significantly higher among puppies (<1 year old) than among adults. Mortality of individuals that showed signs of disease but did not die immediately was not significantly elevated over the following six months. The hunting success and movement patterns of the pack were not affected by the outbreak. Collectively, these data suggest that African wild dogs possess a degree of resistance to anthrax.     

Health at the Sub-catchment Scale: Typhoid and Its Environmental Determinants in Central Division,Fiji

EcoHealth - The impact of environmental change on transmission patterns of waterborne enteric diseases is a major public health concern. This study concerns the burden and spatial nature of enteric...     

Spatial and seasonal patterns in freshwater ichthyofaunal communities of a tropical high island in Fiji

We surveyed freshwater ichthyofaunal communities in streams of Vanua Levu, Fiji, under a range of land cover to assess differential, seasonal effects on fish abundance and diversity. We collected fish from 32 families, 19 genera and 87 species, representing approximately 50% of the known Fijian freshwater and estuarine fish fauna. Position in reach was the strongest overall factor influencing fish abundance and diversity, particularly in the larger, steeper catchments. However, fish communities exhibited strong seasonal specificity with over half (55%) of species observed in only one season. There were greater numbers of estuarine and marine migrants and fishes with poor swimming ability in the dry season, with more schooling species, large predators and fish that prefer muddy benthos in the wet. In the more pristine catchments of Kubulau District, higher species abundance and diversity were observed in the wet season and were associated with significantly greater flow, pH and dissolved oxygen. We observed the opposite pattern for fish diversity and abundance from the more degraded catchments of Macuata Province. These results suggest that the wet season is having a net positive effect on habitable space for fishes in Kubulau and a net negative effect in Macuata, as species may be lost due to increased runoff from heavily cleared and cultivated catchments. Integrated water resource management across the full range of habitats utilized by Fiji’s freshwater fishes is recommended in order to maintain species diversity and abundance.