Decline and potential recovery of Yellow-footed Antechinus in parts of south-eastern Australia: A perspective with implications for management

Summary   The extent and intensity of European-induced changes to ecosystems in south-eastern Australia mean that remaining habitats, despite being degraded, are of high conservation value. Given the extinction of several species of native mammals in the last 160 years in the area, and conservation concerns regarding others, it is important to provide conservation managers with sufficient information to prevent further extinctions and maintain evolutionary potential of the species. A native, carnivorous marsupial, the Yellow-footed Antechinus ( Antechinus flavipes ) exists within these massively altered landscapes. We present conceptual models, derived from the literature, of persistence of populations of Yellow-footed Antechinus both before European colonization and in the 21st century. We conclude that preservation of large trees, restoration of fallen-timber volumes, spring flooding of floodplains and presence of vegetation corridors between forests should be undertaken to prevent local extinctions of Yellow-footed Antechinus. From historic and current gene flow, we identify remnant woodland and forest groupings that we consider should be managed as coherent units.     

Development of a ‘sediment-stress’ functional-level indicator for the seagrass Halophila ovalis

Understanding mechanistic relationships between seagrass and their environmental stressors should be considered for effective management of estuaries and may inform on why change has occurred. We aimed to develop indicators for seagrass health in response to sediment conditions for the Swan-Canning Estuary, south-west Australia. This article describes the development of a new sediment-stress indicator, relating aspects of seagrass productivity with sediment sulfur dynamics. Sulfur stable isotope ratio and total sulfur were measured monthly within the roots, rhizomes and leaves of Halophila ovalis, and significantly varied across sites and months. The growth of seagrass over the summer months appeared restricted by sediment condition, with growth of seagrass lower when sediment derived sulfur and/or total sulfur within rhizome of leaf tissues was higher. H. ovalis appeared quite tolerant of sulfide intrusion within the root compartment, but growth was compromised when sulfide breached the root–rhizome barrier. The tightest correlation between potential sulfur metrics and seagrass growth was observed for the ratio (δ³⁴S_leaf + 30)/(TS_leaf), and it is this ratio that we propose may be a useful sediment-stress indicator for seagrass. The study also highlights that sediment condition needs to be considered at the meadow scale.     

Variation in the timing of river entry of Atlantic salmon (Salmo salar L.) in the Baltic

The timing of river entry in the Atlantic salmon is known to depend on genetic,demographic and environmental factors,but little is known about the relative magnitude of among population and among year variation and covariation in this respect in natural state Atlantic salmon rives.To investigate this,variability in the timing of river entry in three historical Finnish Atlantic salmon populations were analyzed using salmon trap data collected during 1870-1902.The analyses reveled that 1)the timing of river e...     

A molecular phylogeny of aquatic gastropods provides a new perspective on biogeographic history of the Snake River Region

Mitochondrial DNA sequences of aquatic gastropods of the subgenus Pyrgulopsis (Natricola) were analyzed to test a commonly accepted hypothesis concerning the early history of the Snake River in the northwestern US. Distributions of Natricola and other regional biota were previously used to infer that the Snake River flowed to the Pacific through southeastern Oregon and northern California during the Neogene prior to its capture by the Columbia River in the late Pliocene (2 Ma). A molecular phylogeny based on partial sequences of COI and NDI (1149 bp) indicates that the Natricola clade is restricted to the modern Snake-Columbia River Basin and the Oregon Lakes region whereas northern California populations previously assigned to this subgenus belong to other lineages. The Natricola clade is not deeply subdivided into Oregon Lakes and Snake River Basin units consistent with late Pliocene fragmentation of the hypothesized paleodrainage, but instead is shallowly structured and contains multiple transitions among these two geographic areas. The strongly supported sister relationship between Natricola and a species from northwest Nevada (P. imperialis) is consistent with a recent proposal that the ancestral Snake River did not flow through southeast Oregon but instead flowed south to the Humboldt River. Within the context of this hypothesis, the multiple transitions between the Snake River Basin and the Oregon Lakes region that occurred within Natricola may be attributed to a late Pleistocene connection between these areas that was unrelated to the early course of the Snake River.     

Efficiency of Simulium sanctipauli as a vector of Onchocerca volvulus in the forest zone of Ghana

The role of Simulium sanctipauli Vajime & Dunbar (Diptera: Simuliidae) as a vector of Onchocerca volvulus (Leuckart) (Spirurida: Onchocercidae) in the forest zone of central Ghana was studied in the Upper Denkyira district, where onchocerciasis is hyperendemic. Simulium sanctipauli was found to be a highly efficient vector, with a mean of 377 infective (L3) larvae in the heads of 1000 parous and 122 in the heads of 1000 biting flies. The overall infection rate of 44% of the parous flies with L1, L2 and L3 stages of O. volvulus (identity confirmed by polymerase chain reaction) demonstrates marked anthropophily. Female flies dispersed over a wide area and can transmit onchocerciasis up to at least 10 km away from their breeding sites. Annual community-directed treatments with ivermectin did not have a noticeable effect on the infection rates and parasitic loads of fly populations, which were as high 2 months after as 3 months before the distribution of ivermectin. This failure can be attributed to poor coverage, with treatment taken by only 24.4% of the population of the six study villages.     

Archaeaplankton in the Columbia River, its estuary and the adjacent coastal ocean, USA

PCR-amplified 16S rRNA genes from particle-attached and free-living Archaea in the Columbia River estuary, particle-attached Archaea in the river, and Archaea in the adjacent coastal ocean were cloned, and 43 partial sequences were determined. There was a high diversity of Archaea in the estuary, especially among the particle-attached Archaea, with representatives from four major phylogenetic clusters. Eighteen of 21 estuarine clones were closely related to clones from the river and the coastal ocean or to clusters of marine and soil clones identified in other studies. This contrasts with a similar study of the estuarine bacterial community that found 62% of bacterial 16S rRNA clones to be unique to the estuary. Archaea in the estuary were primarily allochthonous, and therefore, unlike the bacteria, probably do not form a native estuarine community.     

Spatial and temporal pattern of introduced Bombus terrestris abundance in Hokkaido, Japan, and its potential impact on native bumblebees

A commercial colony of Bombus terrestris (L.) was introduced to Japan in 1992 for crop pollination in greenhouses. Since then wild colonies have developed and spread in some regions. In the present study, we measured the spatial distribution and temporal change in abundance of B. terrestris in the Chitose River Basin, Hokkaido, Japan to elucidate the relation of greenhouses to the bees distribution and to evaluate its potential effects on native bumblebees. Bumblebees were collected with window traps in windbreak forests roughly 1, 2, 4, and 6 km NNW and SSE of a large greenhouse. The peak catch of B. terrestris queens occurred in early June, suggesting that they had successfully hibernated in the field. The distributions of B. terrestris and the native B. ardens were mutually exclusive, while the native B. hypocrita appeared at all sites. Catches of B. terrestris were restricted to within 4 km of the nearest greenhouse, suggesting that the invasion was still in the initial phase in this area. The reduction in abundance of the native bumblebees in the sites of high B. terrestris abundance suggests the presence of interspecies competition between B. terrestris and the native bumblebees during the early part of the colony activity, although such reduction in B. ardens can be explained by habitat suitability.     

Ichthyofaunal survey of rivers within Ewekoro cement manufacturing operational areas

A total of 298 fish specimens belonging to seven families were caught during ichthyoplanktonic survey of three rivers within the Ewekoro cement facility catchment area located in southwestern Nigeria. The highest numbers of specimens were caught from Alaguntan (37.0%) and Elebute (36.6%) rivers while 28.9% of the fish samples were collected from Itori River. The fish population and species diversity recorded in the catchment rivers were significantly lower (p < 0.05) than comparative catches from Ewekoro River located about 30 km downstream of the factory operational area. The food items ingested by the specimens across the seasons in the catchment rivers revealed obvious differences in diet with some degree of overlap in the fish trophic preferences. However, the omnivorous species dominated the catches in each of the rivers, irrespective of season. Categorization of the fish specimens based on habitat-related adaptive physiology showed that a significant number of the fish from Alaguntan and Itori Rivers have accessory respiratory organs. The four species with accessory respiratory organs were Polypterus senegalus Curv., Clarias gariepinus C. & V., Ctenopoma kingslayae Gun. and Channa obscura Smith. Of the 12 fish species recorded in the Ewekoro cement facility catchment rivers, only P. senegalus, C. gariepinus, C. obscura and Oreochromis niloticus (Trew.) are valuable food fishes in southwestern Nigeria.