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101.
102.
Luke T. Kelly Andrew F. Bennett Michael F. Clarke Michael A. McCarthy 《Conservation biology》2015,29(2):473-481
Fire is used as a management tool for biodiversity conservation worldwide. A common objective is to avoid population extinctions due to inappropriate fire regimes. However, in many ecosystems, it is unclear what mix of fire histories will achieve this goal. We determined the optimal fire history of a given area for biological conservation with a method that links tools from 3 fields of research: species distribution modeling, composite indices of biodiversity, and decision science. We based our case study on extensive field surveys of birds, reptiles, and mammals in fire‐prone semi‐arid Australia. First, we developed statistical models of species’ responses to fire history. Second, we determined the optimal allocation of successional states in a given area, based on the geometric mean of species relative abundance. Finally, we showed how conservation targets based on this index can be incorporated into a decision‐making framework for fire management. Pyrodiversity per se did not necessarily promote vertebrate biodiversity. Maximizing pyrodiversity by having an even allocation of successional states did not maximize the geometric mean abundance of bird species. Older vegetation was disproportionately important for the conservation of birds, reptiles, and small mammals. Because our method defines fire management objectives based on the habitat requirements of multiple species in the community, it could be used widely to maximize biodiversity in fire‐prone ecosystems. Historiales de Incendios Óptimos para la Conservación de la Biodiversidad 相似文献
103.
James J. Bell Emily McGrath Andrew Biggerstaff Tracey Bates César A. Cárdenas Holly Bennett 《Conservation biology》2015,29(1):42-53
Sponges are important for maintaining ecosystem function and integrity of marine and freshwater benthic communities worldwide. Despite this, there has been no assessment of their current global conservation status. We assessed their status, accounting for the distribution of research effort; patterns of temporal variation in sponge populations and assemblages; the number of sponges on threatened species lists; and the impact of environmental pressures. Sponge research effort has been variable; marine sponges in the northeastern Atlantic and Mediterranean and freshwater sponges in Europe and North America have received the most attention. Although sponge abundance has increased in some locations since 1990, these were typically on coral reefs, in response to declines in other benthic organisms, and restricted to a few species. Few data were available on temporal trends in freshwater sponge abundance. Despite over 8500 described sponge species, only 20 are on threatened species lists, and all are marine species from the northeastern Atlantic and Mediterranean. Of the 202 studies identified, the effects of temperature, suspended sediment, substratum loss, and microbial pathogens have been studied the most intensively for marine sponges, although responses appear to be variable. There were 20 studies examining environmental impacts on freshwater sponges, and most of these were on temperature and heavy metal contamination. We found that most sponges do not appear to be threatened globally. However, little information is available for most species and more data are needed on the impacts of anthropogenic‐related pressures. This is a critical information gap in understanding sponge conservation status. Estado Global de la Conservación de Esponjas 相似文献
104.
105.
Understanding antibiotic biodegradation is important to the appreciation of their fate and removal from the environment. In this research an Isotope Ratio Mass Spectrometry(IRMS)method was developed to evaluate the extent of biodegradation of the antibiotic,sulphanilamide, in contaminated groundwater. Results indicted an enrichment in δ~(13)C of8.44‰ from-26.56(at the contaminant source) to-18.12‰(300 m downfield of the source).These results confirm reductions in sulphanilamide concentrations(from 650 to 10 mg/L)across the contaminant plume to be attributable to biodegradation(56%) vs. other natural attenuation processes, such as dilution or dispersion(42%). To understand the controls on sulphanilamide degradation ex-situ microcosms assessed the influence of sulphanilamide concentration, redox conditions and an alternative carbon source. Results indicated, high levels of anaerobic capacity(~50% mineralisation) to degrade sulphanilamide under high(263 mg/L), moderate(10 mg/L) and low(0.02 mg/L) substrate concentrations. The addition of electron acceptors; nitrate and sulphate, did not significantly enhance the capacity of the groundwater to anaerobically biodegrade sulphanilamide. Interestingly, where alternative carbon sources were present, the addition of nitrate and sulphate inhibited sulphanilamide biodegradation. These results suggest, under in-situ conditions, when a preferential carbon source was available for biodegradation, sulphanilamide could be acting as a nitrogen and/or sulphur source. These findings are important as they highlight sulphanilamide being used as a carbon and a putative nitrogen and sulphur source, under prevailing iron reducing conditions. 相似文献
106.
107.
The size and structure of a photographically identified population of reef manta ray, Manta alfredi, were examined at aggregation sites over a four-year period in southern Mozambique. The use and standardisation of photo-ID
techniques was examined as a minimally-intrusive means to study this species. Using these techniques, we report on the size,
structure and seasonality of this population of M. alfredi. In total, 449 individuals were identified during this time period, 40.5% of which were re-sighted on at least one occasion.
The longest period between re-sighting events was 1,252 days. During the study period, annual population size estimates for
M.
alfredi ranged from 149 to 454 individuals. The superpopulation size estimate for the entire study period was 802 individuals, the
first reported for M. alfredi at a monitored aggregation site. A highly significant sex bias was evident with a female:male ratio of 3.55:1. The majority
of rays (89.9% males; 49.7% females) were considered mature, with most individuals between 3.0 and 4.9 m in disc width. Manta alfredi were observed at the study sites in each month of the calendar year. The maximum number of individual rays seen per dive
was 30. Large numbers of rays (20 + per dive) were seen in the months of November, December and January, which coincide with
the breeding season. Natural markings were unique to individuals and did not change substantially with time, which provided
further support for their use in the identification of individual M. alfredi over multiple years. Multiple re-sightings of individual M. alfredi suggest that many individuals in this population exhibit site fidelity to the examined aggregation sites. As target subsistence
fishing for M. alfredi exists along the Mozambican coastline, management efforts to monitor and prevent overexploitation at these critical habitats
should be a priority. 相似文献
108.
Reuel M. Bennett Paul Rodrigo F. Cordero Gershon S. Bautista 《Chemistry and Ecology》2013,29(4):320-328
The reductive adsorption of hexavalent chromium (Cr6+) using six indigenous microorganisms isolated from contaminated soil and water samples was investigated. Quantification of Cr6+ reduction was determined using the 1,5-diphenylcarbazide method followed measuring the absorbance at OD540. Bacterial isolates identified as Klebsiella pneumoniae, Bacillus firmus and Mycobacterium sp. were capable of absorbing Cr6+ efficiently into their biomass, whereas the fungal isolates, Aspergillus flavus, Aspergillus sp. and A. niger were capable of transforming Cr6+ to Cr3+ relative to cell-wall-binding properties. Infrared spectral analysis of functional groups showed that ?OH, ?NH2 and C?O with conjugated ?NH were the binding groups responsible for adsorption of Cr6+ within the biomass of isolates. The data highlight the promising biotechnological application of these isolates in removing carcinogenic and mutagenic Cr6+ from contaminated ecosystems. 相似文献
109.
M. J. O’Riain N. C. Bennett P. N. M. Brotherton G. McIlrath T. H. Clutton-Brock 《Behavioral ecology and sociobiology》2000,48(6):471-477
Meerkats live in co-operatively breeding familial groups in which reproduction is monopolised by a dominant pair of breeders.
Offspring of the breeders are behaviourally subordinate, and typically remain in their natal group as sexually mature, non-breeding
helpers. In this study, we investigated the proximate factors limiting subordinate reproduction. Evidence for reproductive
suppression by dominants was investigated by comparing life history, behaviour and hormonal profiles of dominants and subordinates.
Baseline levels of plasma luteinising hormone (LH) were significantly higher in dominant than in subordinate females. However,
following an exogenous injection of gonadotrophin-releasing hormone (GnRH), both categories had comparable concentrations
of circulating LH. There were no significant differences in pre- or post-GnRH challenge LH levels in dominant or subordinate
males. Reproduction in both dominant and subordinate females rarely occurred in the absence of unrelated males. Given that
groups typically comprise parents and offspring, lack of suitable mates emerged as the primary constraint on subordinate reproduction.
When this constraint was removed, subordinates typically bred but at a lower rate than dominants. This difference in reproduction
may be attributed to intrasexual competition manifested through direct interference by dominant females through subordinate
evictions, infanticide and the abandoning of subordinate litters. We argue that differences in reproductive regulation within
mammalian co-operative breeding systems may be explained by differences in the mating strategy (inbreeding versus outbreeding)
and the probability that subordinates in obligate outbreeding species will encounter unrelated opposite-sex partners.
Received: 19 April 2000 / Accepted: 17 July 2000 相似文献
110.
Darla Hatton MacDonald Mary Barnes Jeff Bennett Mark Morrison Michael D. Young 《Journal of the American Water Resources Association》2005,41(3):719-728
ABSTRACT: A series of reforms in the water industry in Australia has created a demand from the industry and regulators for objective methodologies to evaluate incremental changes in the customer service standards. In this paper, the use of choice modeling for estimating implicit prices associated with urban water supply attributes is explored. Results from multinomial logit (MNL) and random parameters logit (RPL) models show that increases in annual water bills and the frequency of future interruptions were the most important attributes. Implicit price confidence intervals based on the best models suggest that people are willing to pay positive amounts to achieve a water supply that is less frequently interrupted. The provision of alternative water supplies during an interruption and notification of the interruption were found to be unimportant to respondents. Choice modeling proved to be a useful technique and provided the industry and regulators with additional information for standard setting. 相似文献