Contractual National Parks and the Makuleke Community

Contractual national parks in South Africa are established on land owned either by the state or by a group of private individuals, but managed by South African National Parks (SANP) according to the terms of a joint management agreement drawn up by a joint management committee consisting of representatives from SANP and the landowners. Since majority rule in 1994, contractual national parks have been seen as a model through which the country's conservation as well as development objectives can be met, particularly where landowners are previously disadvantaged communities. This study looks at the Makuleke region of Kruger National Park in order to ascertain how successful the contractual national park model is in meeting conservation, social, and economic objectives for the area.     

Spatial and trophic partitioning in cryptic fish communities of shallow subtidal reefs in False Bay, South Africa

Thirty-nine species of cryptic fishes belonging to 16 families were captured on shallow reefs (0-20 m) in False Bay, South Africa using the ichthyocide rotenone. Five samples were collected in each of four depth zones (0-5, 6-10, 11-15 and 16-20 m). The area from which fish were collected in each sample was measured to give an estimate of density. The overall density of cryptic fishes in the area was 3.41 fish m^-2, with the families Congrogadidae and Clinidae being numerically dominant, representing 27.9% and 22.3% of the total sample respectively. The Clinidae were by far the most diverse group, being represented by 17 species, while no other family was represented by more than three species. Multivariate analysis of numerical density revealed that partitioning of spatial resources did occur, with the shallowest samples (0-5 m) forming a group discrete from the deeper samples (6-20 m). Further analysis indicated that the amount of algal cover present was the most important factor influencing community structure, although the abundance of algae is in turn related to depth. The shallowest samples were dominated by members of the families Clinidae, Gobiesocidae and Bythitidae, while the Cheilodactylidae, Tripterygiidae and Ariidae were more important components of deeper water communities (6–20 m). Analysis of percentage volume of prey items in the diets of 21 species revealed that only two species shared diets that were more than 50% similar, and that partitioning of trophic resources was considerable. This revised version was published online in July 2006 with corrections to the Cover Date.     

Changes in Prokaryote and Eukaryote Assemblages Along a Gradient of Hydrocarbon Contamination in Groundwater

Groundwater biota are particularly sensitive to environmental perturbations such as groundwater contamination. The diversity of prokaryotic and eukaryotic biota has been examined along a gradient of chlorinated hydrocarbon (CHC) contamination in the Botany Sands, an urban coastal sand-bed aquifer (Sydney, Australia). Molecular techniques were used to analyze the richness and composition of prokaryote and eukaryote assemblages using 16S and 18S rDNA, respectively. Taxon richness did not change significantly along the gradient for either prokaryotes or eukaryotes; however, significant shifts in assemblage composition were evident for both groups. Assemblage changes were most strongly correlated with concentrations of the major CHC, cis-1,2-dichloroethene, but the concentrations of a number of the contaminants were also correlated, making it difficult to infer if effects were due to any particular contaminant. The presence of cis-1,2-dichloroethene and other secondary ethenes suggests in situ breakdown of the primary CHCs via natural attenuation. The current focus of management of the Botany aquifer is to stop the contaminant plume reaching the adjoining estuary. This approach is clearly justified given the changes evident in the microbial assemblages in the groundwater, which are a likely consequence of the contamination.     

Comparative diel oxygen cycles preceding and during a Karenia bloom in Sarasota Bay,Florida, USA

The diel change in dissolved oxygen concentrations were recorded with an automated incubator containing a pulsed oxygen sensor in Sarasota Bay, Florida. The deployments occurred during a ‘pre-bloom’ period in May to June 2006, and during a harmful algal bloom dominated by Karenia brevis in September 2006. The diurnal (daylight) increase in dissolved oxygen concentrations varied from 16 to 104 μmol O₂ l⁻¹ with the corresponding nocturnal decrease in oxygen varying from 16 to 77 μmol O₂ l⁻¹. Nocturnal respiration consumed 42–113% of the diurnal net oxygen production with the minimum and maximum during the pre-bloom period. Hourly production rates closely followed fluctuations in irradiance with maximum rates in the late morning. Hourly oxygen utilization rates (community respiration) at night were highest during the first few hours after sunset.     

Community composition has greater impact on the functioning of marine phytoplankton communities than ocean acidification

Ecosystem functioning is simultaneously affected by changes in community composition and environmental change such as increasing atmospheric carbon dioxide (CO₂) and subsequent ocean acidification. However, it largely remains uncertain how the effects of these factors compare to each other. Addressing this question, we experimentally tested the hypothesis that initial community composition and elevated CO₂ are equally important to the regulation of phytoplankton biomass. We full‐factorially exposed three compositionally different marine phytoplankton communities to two different CO₂ levels and examined the effects and relative importance (ω²) of the two factors and their interaction on phytoplankton biomass at bloom peak. The results showed that initial community composition had a significantly greater impact than elevated CO₂ on phytoplankton biomass, which varied largely among communities. We suggest that the different initial ratios between cyanobacteria, diatoms, and dinoflagellates might be the key for the varying competitive and thus functional outcome among communities. Furthermore, the results showed that depending on initial community composition elevated CO₂ selected for larger sized diatoms, which led to increased total phytoplankton biomass. This study highlights the relevance of initial community composition, which strongly drives the functional outcome, when assessing impacts of climate change on ecosystem functioning. In particular, the increase in phytoplankton biomass driven by the gain of larger sized diatoms in response to elevated CO₂ potentially has strong implications for nutrient cycling and carbon export in future oceans.     

The bacterial communities of bioelectrochemical systems associated with the sulfate removal under different pHs

Sulfate contamination in ecosystems has been a serious problem. Among various technologies, bioelectrochemical systems (BESs) show the advantage of no-pollution and low-cost for removing sulfate. In order to further expound the biological process of sulfate removal in BESs, 454 pyrosequencing was applied to analyze the bacterial communities under different pH conditions. The bacterial community profiles were analyzed from three aspects: (a) the α-diversity and β-diversity of bacterial communities, (b) the distribution of bacterial phylotypes, and (c) the characterizations of dominant operational taxonomic units (OTUs). We demonstrated that the indexes of phylotype richness and phylogenetic diversity were positively correlated across the pH gradient in the BESs. Among the dominant OTUs, the OTUs which were highly similar to Desulfatirhabdium butyrativorans, Desulfovibrio marrakechensis and Desulfomicrobium sp. might participate in removing sulfate. Standing on genus level, Desulfomicrobium and Sulfuricurvum play conducing and adverse roles for sulfate removal in alkaline condition, respectively. Desulfovibrio contributed to removing sulfate in the neutral and acidic conditions, while Thiomonas mainly weakened the performance of sulfate removal in neutral pH condition. These results further clarified how pH condition directly affected the bacterial communities, which consequently affected the performance of sulfate pollutant treatment using BESs.