Assessment of long-term changes in habitat availability for Arctic charr (Salvelinus alpinus) in a temperate lake using oxygen profiles and hydroacoustic surveys

1. Hydroacoustics (2002–04) and long‐term oxygen data (1969–2004) have been used in conjunction to examine the habitat of Arctic charr in the north and south basins of Windermere, U.K., a temperate lake subjected to cultural eutrophication and subsequent nutrient management. 2. Since 1969 there has been a gradual decline in the oxygen concentration in the bottom waters of both basins of 0.03–0.04 mg L^?1year^?1, resulting in up to 43% of the volume of the south basin having an oxygen concentration <5 mg L^?1 in the early autumn. 3. Hydroacoustic data indicate that most Arctic charr routinely avoid the upper 10 m of the water column irrespective of temperature, with the implication that an observed gradual warming of the lake has not yet directly impacted upon their habitat. 4. In recent years there has been a behavioural response of the Arctic charr population to migrate vertically to avoid oxygen concentrations <2.3–3.1 mg L^?1. Further, the depth of the lower bound of the Arctic charr population is shown to be highly correlated with the deep water oxygen concentration throughout the year prior to autumnal overturn.     

Making the biodiversity monitoring system sustainable: Design issues for large‐scale monitoring systems

Abstract There is strong demand for information about the status of, and trends in, Australia's biodiversity. Almost inevitably, this demand for information has led to demand for a broad‐scale monitoring system. However, the decision to embark on a monitoring system should only be made once it has been established that a monitoring system is the optimal way to inform management. We stress the need to invest resources in assessing whether a monitoring system is necessary before committing resources to the design and implementation of the system. Current debate associated with the design of a biodiversity monitoring system has similarities to the debate within the range management profession in the early 1970s. The experience with range monitoring shows that large‐scale monitoring systems such as those being proposed will require considerable resources, recurrently expended into the distant future, but with only a limited ability to adapt to new demands. Those involved in any biodiversity monitoring system will need to understand the implications of investing in a long‐term monitoring programme. Monitoring sustainability will only be possible if the monitoring system is itself sustainable. We discuss a number of issues that need to be addressed before the system is at all sustainable. These attributes are a mix of biophysical, social and institutional attributes and highlight the view that monitoring systems of the type being suggested comprise an unusual mixture of attributes not found in typical scientific activity. The present paper is not a technical manual, but rather considers some of the design issues associated with designing and implementing large‐scale monitoring systems.     

Leaf phenology mediates provenance differences in herbivore populations on valley oaks in a common garden

1. Plants from different populations often display a variation in herbivore resistance. However, it is rarely understood what plant traits mediate such differences. 2. It was tested how leaf phenology affects herbivore populations in a 15‐year‐old common garden of valley oaks (Quercus lobata Née) with different populations and maternal parents from throughout the Q. lobata range. 3. The abundance of leaf miners (Stigmella sp. Shrank) and leaf phenology of oaks in the common garden was measured. 4. Leaf miner abundance varied among provenance locations (population), but not among maternal parents within populations. Leaf phenology varied by provenance location and maternal parent, and trees that leafed out earlier accrued higher leaf‐miner abundance. Path analysis indicated that leaf phenology was the likely driver of provenance and parental differences in resistance to leaf miners. 5. Understanding population differences is particularly important when considering transport of genotypes for ornamental or restoration purposes. The present study suggests that similarity in leaf phenology may be one factor that could be used to find genotypes with a similar herbivore resistance to local genotypes.     

The Effects of Temperature and Daylength on the Rate of Development of Pigeonpea

Eleven cultivars of pigeonpea, representing five different maturitygroups, were grown under controlled conditions to determinehow the rate of development from sowing to flower bud initiation(FBI) and sowing to flowering was affected by temperature anddaylength, the two environmental variables thought to have mostinfluence on reproductive development. Both temperature and daylength had substantial effects overthe range 16–32 C and 10–14 h respectively. Comparisonswithin the 12 h daylength treatment showed no consistent patternwith mean temperature. A discrete-rate analysis was used todetermine the effect on development of each of the temperaturesmaking up the various treatment combinations of day and nighttemperature. The rate of development from sowing to FBI varied among cultivars.The responses to temperature were all strongly curvilinear withoptima between 20 and 24 C. The rate of development from sowingto flowering showed a similar pattern. The effect of daylengthon the rate of development was the greatest between sowing andFBI, with the greatest sensitivity between 12 and 14 h. For the range of conditions considered, temperature had at leastas great an influence as daylength on the rates of developmentfrom sowing to FBI and from sowing to flowering. Some of theresponses to time of planting that have previously been attributedto daylength effects may, in fact, have been due to temperature.The responses to temperature of reproductive and vegetativedevelopment are very different. Phenology, Cajanus cajan     

Barlow's Lark: a new species in the Karoo Lark Certhilauda albescens complex of southwest Africa

The Karoo Lark Certhilauda albescens complex, endemic to southwest Africa, is characterized by regional phenotypic variation. Recent consensus has been to recognize two species, Dune Lark Certhilauda erythrochlamys and Karoo Lark Certhilauda albescens, but intermediate forms around the mouth of the Orange River have resulted in some authors treating it as a single polytypic species complex. We reexamined the status of taxa in this group by sequencing a segment of the mitochondrial DNA cytochrome b gene. Most samples were from the area around the mouth of the Orange River, where there is considerable local phenotypic variation. Our results indicate that the complex comprises three species, Karoo Lark, Dune Lark and Barlow's Lark Certhilauda barlowi, separated by 1.9-5.5% sequence divergence. There were no sequence differences among described subspecies, but there was limited variation among Dune Lark individuals (sequence divergence values 0.2-0.4%). The Red Lark Certhilauda burra is closely related to the Karoo Lark complex; indeed, it may be that Karoo Lark is the ancestral form. There was morphological (biometrics and plumage) and behavioural (male display song structure) support for the recognition of Barlow's Lark as a separate species. Species ranges within the complex are allopatric or narrowly parapatric, and they occur in different habitats and climatic conditions. Discriminant function analysis correctly identified 99% of skins assigned to taxa based on range, but a few individuals collected in the contact zone between Karoo and Barlow's Larks exhibited intermediate phenotypes, and further investigations are warranted to search for evidence of hybridization. The newly recognized Barlow's Lark has a maximum range of 18,000 km². It appears to have disappeared from heavily grazed farms around Aus, southern Namibia, and occurs almost exclusively in diamond mining areas, where domestic livestock are excluded. Changes to land use practices which reduce vegetation cover could seriously impact this species.     

Regional growth patterns in the hypocotyls of etiolated and green cress seedlings in light and darkness

Abstract. A system is described whereby seedling development can be analysed in terms of growth rates of specific 1 mm regions of the hypocotyl. The technique involves time-lapse photography of marked hypocotyls in a specially designed chamber which accommodates seedlings in various orientations with respect to gravity, and under irradiation regimes differing in light quality, quantity and direction. The results of a preliminary study of the upward growth of etiolated or green cress seedlings in darkness or overhead while light are reported. Highest growth rates in etiolated seedlings were observed in zones in the upper one-third of ihe hypocotyl. In green seedlings, growth was more prominent within the subapical zones. Light further restricted growth of the median and basal zones in both types of seedling. However, in their immediate responses to the onset of irradiation, green and etiolated seedlings differed markedly. In etiolated seedlings, recovery of growth at the apex was accompanied by the development of inhibition in the median-basal regions; green seedlings showed a transient inhibition of growth in the apical zone together with a strong immediate inhibition in the median-basal regions.     

Functional Properties of Cloned Melanogenic Proteins

Several genes critical to the regulation of melanin production in mammals have recently been cloned and characterized. They map to the albino, brown, and slaty loci in mice, and encode proteins with similar structures and features, but with distinct catalytic capacities. The albino locus encodes tyrosinase, an enzyme with three distinct catalytic activities—tyrosine hydroxylase, 3,4-dihydroxyphenylalanine (DOPA) oxidase and DHI (5,6-dihydroxyindole) oxidase. The brown locus encodes TRP-l (tyrosinase-related protein-I), which has the same, but greatly reduced, catalytic potential. The slaty locus encodes TRP-2, another tyrosinase related-protein, which has DOPAchrome tautomerase activity. In this study we have examined the enzymatic interactions of these proteins, and their regulation by a novel melanogenic inhibitor. We observed that tyrosinase activity is more stable in the presence of TRP-l and/or TRP-2, but that the catalytic function of TRP-2 is not affected by the presence of TRP-1 or tyrosinase. Other factors also may influence melanogenesis and a unique melanogenic inhibitor suppresses tyrosinase and DOPAchrome tautomerase activities, but does not affect the spontaneous rate of DOPAchrome decarboxylation to DHI. The results demonstrate the catalytic functions of these proteins and how they stably interact within a melanogenic complex in the melanosome to regulate the quantity and quality of melanin synthesized by the melanocyte.     

Adipokinetic hormone of the true armyworm, Pseudaletia unipuncta: immunohistochemistry, amino acid analysis, quantification and bioassay

Abstract A cluster of five to seven AKH-like immunoreactive cells lie in each lobe of the paired corpora cardiaca of the true armyworm, Pseudaletia unipuncta. These cells form a mesh work of immunoreactive processes within the corpora cardiaca, and immunoreactive tracts projecting posteriorly over the aorta.
Reversed-phase high performance liquid chromatography of extracts of the corpora cardiaca of P.unipuncta revealed a single large U.V. absorbent peak with a retention time identical to synthetic Manduca- AKH. Amino acid analysis of the contents of this peak yielded a composition identical to that of synthetic Manduca-AKH which was analysed in a parallel manner. Furthermore the material within the peak possessed adipokinetic activity when bioassayed in day 2 adult male P. unipuncta. The corpora cardiaca of similar individuals were found to contain approximately 17.6ng (17.6pmol) of Manduca-AKH equivalents per pair.
Injection of Manduca-AKH into 2-day-old adult male P.unipuncta resulted in a dose-dependent elevation in haemolymph lipid levels with a maximum level of 80–90μmg/μl obtained with 5–10 ng of Manduca-AKH. Continuous flight also elevated haemolymph lipid levels in day 4 adult males with a significant elevation evident in the first samples taken after 15 min of flight and lipid levels plateauing at approximately 100 μg/μl by about 60 min of flight.