Effects of pioneering plants on microbial structures and functions in a glacier forefield

This study investigates the small-scale spatial impact of the pioneering plant Leucanthemopsis alpina (L.) Heywood (L. alpina) on biological and chemical–physical parameters in an early successional stage of a glacier forefield. Considering the frequent occurrence of isolated patches of this pioneer plant in the forefield of the Dammaglacier (Switzerland), we hypothesized that the impact of the plant would establish gradients in nutrients, and microbial community structure and activity that may be of importance for the successional processes occurring in the forefield. Our results indicated that, in young successional soils, the rhizosphere effect of L. alpina plant patches can influence bacterial cell numbers and activities not only within the root zone, but even at 20 cm distance from the plant. Microbial cell counts, active cells, and saccharase, glucosidase, and acid phosphatase activities revealed significant distance effects, decreasing from soil directly underneath the plant to soils at 20 and 40 cm distance. Soil chemical and physical parameters did not exhibit significant trends. Fingerprinting analysis of amplified 16S rDNA fragments was used to characterize the microbial community. A selective effect of the plant on the microbial community could not be shown because the bacterial communities were similar regardless of distance to the plant.     

Fish community composition of a tropical nonestuarine embayment in Zanzibar,Tanzania

ABSTRACT:   By using a seine net, fish samples were taken from the nonestuarine Chwaka Bay (Zanzibar, Tanzania) from the mangroves, mud/sand flats and seagrass beds. Sampling was done twice per month between November 2001 and October 2002. In total, 150 fish species belonging to 55 families were identified. Diversity ( H' ) ranged from 1.9 in mud/sand flats to 3.4 within the Chwaka seagrass beds. Mean density of fishes was significantly higher in the mangrove creeks than in any other habitat (mean = 238.7 ind./1000 m²). Highest, but non-significantly different mean biomasses were recorded in the mangrove creeks (1.7 kg/1000 m²) and in the Marumbi seagrass beds (1.6 kg/1000 m²). The mangrove channel had the lowest biomass (0.6 kg/1000 m²). A high overlap in species composition (as high as 93.4% similarity) was found for adjoining habitats (i.e. mangrove creeks and mangrove channel), while habitats that were far apart showed low overlap (6.6% similarity for the Marumbi seagrass beds and mangrove creeks). On average, 58.4 and 63.2% in terms of abundance and biomass, respectively, of the fish assemblage of Chwaka Bay were of commercial fishery importance. Thus, Chwaka Bay appears to be an important juvenile habitat for various commercially important fish species.     

Context is more important than habitat type in determining use by juvenile fish

Context

Habitat characteristics are often equated with habitat function for animals. However, in heterogeneous landscapes, similar habitat types occur in different environmental contexts. In the marine realm, landscape studies have been confined to particular environments, rather than encompassing entire seascapes, due to incompatible sampling methods required in different situations.

Objectives

We examined the interactive structuring effects of local habitat characteristics and environmental context on assemblage composition.

Methods

We used a single technique—remote underwater video census—to explore the importance of habitat type (biotic structural components, substrate, and depth) and environmental context (marine vs estuarine) in structuring juvenile fish assemblages throughout an entire coastal region. In this model system, a range of structural habitat types were present in both estuarine and marine contexts.

Results

The 1315 video surveys collected show a clear hierarchy in the organisation of juvenile fish communities, with assemblages first distinguished by environmental context, then by habitat type. Marine and estuarine mangroves contained entirely different assemblages, and likewise for rocky reefs and submerged aquatic vegetation. Our results suggest that two functionally different ‘seascape nursery’ types exist at local scales within a single region, defined by their context.

Conclusions

The context of a location can be of greater significance in determining potential habitat function than what habitat-forming biota and substrates are present, and apparently similar habitat types in different contexts may be functionally distinct. These findings have important implications for local-scale management and conservation of juvenile fish habitats, particularly in regard to offsetting and restoration.

     

The effect of mass-flowering orchards and semi-natural habitat on bumblebee colony performance

Landscape Ecology - Bumblebees are important pollinators for agricultural crops and wild plants. However, agricultural intensification and loss of semi-natural habitat may have adverse effects on...     

Conflicts between Amur (Siberian) tigers and humans in the Russian Far East

In 1999, the Russian Federation created a Tiger Response Team (TRT) to investigate and intervene in human–tiger conflicts. We examined data collected on human-Amur tiger (Panthera tigris altaica) conflicts from January 2000 through February 2009 to: (1) summarize and characterize human–tiger conflicts in the area, (2) examine causes of human–tiger conflicts, and (3) attempt to evaluate the effectiveness of the TRT. The team investigated 202 conflicts. Both attacks on humans and depredations were greatest in winter (X² = 9, df = 3, P = 0.03 and X² = 64, df = 3, P < 0.001, respectively). Tiger depredation on domestic animals was the most common type of conflict reported (57%), followed by tigers near human habitations (22%), miscellaneous conflicts (12%), and attacks on humans (9%). Dogs were killed more commonly than other domestic animals (63% of 254 animals), likely because livestock were well managed. Nineteen attacks on humans were recorded resulting in 11 injuries and 2 deaths. Nearly four tigers per year (n = 32 tigers) died, were killed, or were removed from the wild, and all but 1 of 20 tigers killed or removed from the wild by the TRT were considered unfit to survive in the wild. Attacks on humans (n = 19) were most often (77%) by wounded tigers (80% of injuries were human-caused) and commonly provoked (47% of attacks). The effectiveness of interventions focused on reducing depredation on domestic animals was unclear, but data suggested that removal of injured and other unhealthy tigers from the wild by the Tiger Response Team resulted in fewer human deaths. Our recommendations include that the TRT continues to work to reduce conflict by rapidly removing debilitated tigers from the wild, explores different methods and technologies for reducing depredation on domestic animals, and increases their efforts to maintain tigers in the wild through telemetry monitoring, translocation, and rehabilitation of orphaned cubs. Further, standardized data should be collected to evaluate all interventions, with information from evaluation guiding an adaptive management component of their human–tiger conflict mitigation activities. This process should occur across tiger landscapes in Asia to allow rapid assessment of interventions.     

Cytokine profiles and phenotype regulation of antigen presenting cells by genotype-I porcine reproductive and respiratory syndrome virus isolates

ABSTRACT: The present study examined the immunological response of antigen presenting cells (APC) to genotype-I isolates of porcine reproductive and respiratory syndrome virus (PRRSV) infection by analysing the cytokine profile induced and evaluating the changes taking place upon infection on immunologically relevant cell markers (MHCI, MHCII, CD80/86, CD14, CD16, CD163, CD172a, SWC9). Several types of APC were infected with 39 PRRSV isolates. The results show that different isolates were able to induce different patterns of IL-10 and TNF-α. The four possible phenotypes based on the ability to induce IL-10 and/or TNF-α were observed, although different cell types seemed to have different capabilities. In addition, isolates inducing different cytokine-release profiles on APC could induce different expression of cell markers.