Nutrient deficiencies affecting peanut production in soils of northeast Thailand

Peanut is widely grown in the rainy season on upland soils (mostly Paleustults) in northeast Thailand. The nutrient status of these soils for peanut production has not been adequately assessed. Response to phosphorus, potassium, sulfur, and copper on a range of soil types of this region have been obtained in pot trials using pasture legumes (Wilaipon 1976). The present experiments were set up to identify nutrient deficiencies which could limit yield and kernel quality of peanut on an Oxic Paleustult (Khorat series)

Teachers’ professional learning: perspectives and reflections of practising teachers

This thesis uses a case study to explore teachers’ professional learning in one secondary school in the south of England. An interpretive, qualitative case study approach was adopted. Data were collected using semi-structured interviews, questionnaires and staff biographies to explore the key research questions. These investigated how the teachers perceive their own learning and development, what teachers think they learn and develop and what activities impact teachers’ learning and development. A review of the conceptual frameworks focused on three different areas. Firstly, a consideration of how teachers and adults define their own learning. Secondly teachers’ knowledge and skills base were explored; looking in particular at what authors argue constitute teachers’ knowledge. Finally, there was an overview of the varied activities and experiences that affect and impact teachers’ learning. Analysis of the data indicated that secondary school teachers perceive their learning through the lens of acquisition and a new perspective described by participants as ‘developmental’. The teachers in the study also showed that those who had been teaching for longer had different perceptions of learning from those with less experience. A teacher’s knowledge base was considered to consist of knowledge and skills related to the school, subject and personal efficacy of the teacher. The content of teachers’ knowledge, however, was influenced by external factors such as policy and social changes in education. Finally, the study found that teachers learnt from a wide range of formal and informal activities. Formal activities tended to be less successful if the aims were not shared and the teachers felt the learning was imposed. Informal activities were more successful as they were normally instigated by staff with their own professional development in mind. Drawing together these findings the study proposes a new model of teacher learning

Competition between wild and captive-bred Penaeus plebejus and implications for stock enhancement

The mechanisms that drive density dependence are rarely studied in the applied context of population management. We examined the potential for competition for food and shelter and the resulting demographic density dependence to influence how well populations of the eastern king prawn Penaeus plebejus Hess can recover following marine stock enhancement programmes in which captive-bred juveniles are released into the wild. Specifically, manipulative laboratory experiments were used to quantify the differential effects of competition for food and competition for shelter on survival of wild and captive-bred P. plebejus as densities were increased and as each category of P. plebejus (wild or captive-bred) was supplemented with the alternate category. Increasing population densities when food and shelter were limited lowered survival for both categories. When food was limited, survival of both categories was unaffected by addition of the alternative category. Adding wild P. plebejus to their captive-bred counterparts when shelter was limited under laboratory conditions resulted in significantly higher mortality in captive-bred individuals. In contrast, adding captive-bred P. plebejus to wild individuals under these conditions did not affect wild P. plebejus. We conclude that if the current results can be extended to wild conditions, competition for shelter may lead to the loss of captive-bred P. plebejus, thereby reducing the intended outcomes of stock enhancement. This highlights the importance of investigating interactions between wild and captive-bred animals prior to stock enhancement to predict long-term outcomes and identify situations where stock enhancement could be an effective response to the loss of populations or recruitment limitation

Dolphin prey availability and calorific value in an Estuarine and coastal environment

Prey density has long been associated with prey profitability for a predator, but prey quality has seldom been quantified. We assessed the potential prey availability and calorific value for Indo-Pacific bottlenose dolphins (Tursiops aduncus) in an estuarine and coastal environment of temperate south-western Australia. Fish were sampled using three methods (21.5 m beach seine, multi-mesh gillnet, and fish traps), across three regions (Estuary, Bay, and Ocean) in the study area. The total biomass and numbers of all species and those of potential dolphin prey were determined in austral summers and winters between 2007 and 2010. The calorific value of 19 species was determined by bomb calorimetry. The aim of the research was to evaluate the significance of prey availability in explaining the higher abundance of dolphins in the region in summer vs. winter across years. A higher abundance of prey was captured in the summer (mean of two summer seasons 12,080 ± 160) than in the winter (mean of two winter seasons = 7358 ± 343) using the same number of gear sets in each season and year. In contrast, higher biomass and higher energy rich prey were captured during winters than during summers, when fewer dolphins are present in the area. Variability was significant between season and region for the gillnet (p < 0.01), and seine (p < 0.01). The interaction of season and region was also significant for the calorific content captured by the traps (p < 0.03), and between the seasons for biomass of the trap catch (p < 0.02). The dolphin mother and calf pairs that remain in the Estuary and Bay year round may be sustained by the higher quality, and generally larger, if lesser abundant, prey in the winter months. Furthermore, factors such as predator avoidance and mating opportunities are likely to influence patterns of local dolphin abundance. This study provides insights into the complex dynamics of predator-prey interactions, and highlights the importance for a better understanding of prey abundance, distribution and calorific content in explaining the spatial ecology of large apex predators

The effect of copper on nitrogen fixation in subterranean clover (Trifolium subterraneum)

Copper deficiency decreased nitrogen fixation in subterranean clover. Three lines of evidence support this conclusion. Firstly, while both copper and nitrogen application increased the growth of the legume the interaction between copper and nitrogen on growth was negative. Secondly, the application of copper increased the concentrations of both total and protein nitrogen in the plant. Lastly, nitrogen fixation as measured by the acetylene reduction assay increased with copper application to the soil

An evaluation of an iterative harvest strategy for data-poor fisheries using the length-based spawning potential ratio assessment methodology

Data on the length structure of exploited stocks are one of the easiest sources of information to obtain for data-poor fisheries, and have the potential to provide cost-effective solutions to the management of data-poor fisheries. However, incorporating the results from stock assessments into a formal harvest strategy, defined here as a harvest management system that incorporates monitoring, assessment, and decisions rules for a specific fishery, usually requires information on the total catch or catch-per-unit effort, data that are not available for many data-poor fisheries. This paper describes and tests a harvest strategy where only length composition data of the catch and knowledge of basic biological parameters are available. The harvest strategy uses a recently developed methodology for stock assessment that estimates the spawning potential ratio (SPR) for an exploited stock from the length structure of the catch (the length-based SPR model; LB-SPR), and uses an effort-based harvest control rule to iteratively drive fishing pressure towards a target level of SPR (40%). A management strategy evaluation framework was used to explore the behaviour of various parameterizations of the harvest control rule for three species with a diverse range of life-histories and M/k ratios ranging from 0.36 (unfished population dominated by large fish) to the Beverton-Holt invariant M/k of 1.5 (unfished population dominated by smaller fish). For all three species the harvest strategy was able to guide the fisheries towards the target SPR, although the time taken for the SPR to stabilise at the target SPR was greatest for the species with the greatest longevity and the lowest M/k. The results of this proof-of-concept study demonstrate that the combination of the LB-SPR assessment model with an iterative, effort-based harvest control rule can successfully rebuild an overfished stock back to sustainable levels or fish down a stock to the target SPR without significantly overshooting the target

Regional differences in the feeding of the ambush predator Neosebastes pandus and comparisons of diets in the Scorpaenidae, Triglidae and Platycephalidae

This study provides a comprehensive assessment of the dietary composition of the ambush predator Neosebastes pandus and compares the diets of 49 species from 39 studies of three benthic predatory families in the Scorpaeniformes: Scorpaenidae (20 species), Triglidae (19 species) and Platycephalidae (10 species). A total of 275 N. pandus were collected from the west (Rottnest Island) and south coasts (Esperance) of south‐western Australia and the percentage frequency and volumetric contribution of the stomach contents identified. Fish from the west coast consumed a greater mean number of broad taxonomic groups and were more diverse in their diet than fish from the south coast. Cephalopods, brachyurans and teleosts were the largest overall contributors to diet, with teleosts being more important to diets of west‐coast fish and polychaetes for south‐coast fish. This reflects differences in habitat between the two locations. Dietary composition also changed with increasing body size, reflecting morphological changes that allow bigger fish to capture and ingest larger, more mobile prey. Meta‐analysis of the diets of 49 species of scorpaenid, triglid and platycephalid revealed that they feed predominantly on teleosts and large crustaceans. Significant differences in diet were detected among families, with platycephalids being the most distinct and feeding more on teleosts than scorpaenids and triglids

The influence of sediment compositions on the decline of Metapenaeus dalli in a temperate Australian estuary

Abundances of the western school prawn (Metapenaeus dalli) in the Swan-Canning Estuary have declined markedly in the last fifty years. Together with the decrease in abundance, there is strong anecdotal evidence from recreational fishers that the spatial distribution of this penaeid has changed as this species no longer being caught in the middle and upper reaches of the estuary. This is a marked shift in distribution, as work conducted in the 1980s showed that individuals of this species moved upstream from the lower reaches of estuary once salinity in these upstream areas reached 30. While, declining rainfall has resulted in these waters being more saline, our data show that these reaches are not utilised to the same extent by individuals of M. dalli. The research presented in this poster investigates the hypothesis that changes in sediment composition may be responsible for this shift in the spatial and temporal use of the estuary by this species. The implications of this research on the restocking program for M. dalli are discussed

Trophic flows, kelp culture and fisheries in the marine ecosystem of an artificial reef zone in the Yellow Sea

This study evaluates the ecosystem structure and function of the nearshore reefs in the Lidao coastal ecosystem of northern China, a region of intensive kelp aquaculture, and fisheries enhancements, including the deployment of artificial reefs and release of cultured marine species. An Ecopath model, with 20 functional groups representing 81 species, was developed for a representative area in the region and Ecosim was used to explore two scenarios for alternative fishing practices and surrounding aquaculture activities. The mean trophic levels (TLs) of the functional groups ranged from 1.0 for the primary producers (phytoplankton, benthic algae and seagrass) and detritus to 4.14 for Type III fishes (fishes found in the water column above the artificial reefs, e.g., Scomberomorus niphonius). The mean transfer efficiency through the whole system was 11.7%, and the ecosystem had a relative low maturity, stability and disturbance resistance, indicating that it was at a developing stage. Nearly half of the total system biomass (48.9% of 620.20 t km−2 year−1), excluding detritus, was comprised of benthic finfish and invertebrates. The total yield from all fisheries (86.82 t/km2/year) was dominated by low trophic level herbivorous and detritivorous species, such as the sea cucumber Apostichopus japonicus (TL = 2.1, 46.07%), other echinoderms (sea urchins Asterias amurensis and Strongylocentrotus nudus, TL = 2.1, 34.6%) and abalone Haliotis discus hannai (TL = 2.0, 18.4%), and as a consequence, the mean TL of the catch was low (2.1). The results from the Ecosim simulation of closing all fisheries for 20 years predicted an increase of about 100% in the relative biomass of the main exploited species, A. japonicus and H. discus hannai. The simulated removal of all kelp farms over 10 years resulted in a two fold increase in the relative biomass of Type III fishes and a 120% increase in their main prey (i.e. Small pelagic fish), while the relative biomass of A. japonicus and Heterotrophic bacteria decreased by 31.4% and 12.7%, respectively. These predictions indicate that nearshore kelp cultivation favours benthic, rather than water column production, and is likely to be providing energy subsidies for the stock enhancement of benthic species in this region

Assessing the sediment preference of a penaeid prawn to inform release strategies

The abundance of the Western School Prawn (Metapenaeus dalli) declined markedly in the Swan-Canning Estuary after the 1960s, resulting in the initiation of a restocking program in 2012. Further to the decline in abundance, anecdotal evidence from recreational fishers indicated that there had been a spatial shift in the distribution of this prawn. To test the hypothesis that a change in sediment composition may be responsible, the density of M. dalli, recorded monthly between October 2013 and August 2014, was correlated against sediment organic matter content and grain size distribution. Densities of M. dalli were found to differ among sediment types in summer, but not winter. Controlled laboratory experiments were used to investigate whether M. dalli exhibited a preference for sediments from either the upper or lower reaches of their distribution within the estuary. Prawns exhibited a preference for nearshore and offshore sediments that contained a lower percentage contribution of larger grain sizes and/or a higher percentage contribution of finer grain sizes, i.e. sediments from the lower rather than upper reaches. These experiments also revealed that emergence and activity rates of M. dalli are strongly related to photoperiod, with individuals preferring to remain buried during daylight hours and become active during darkness. Visual observations also indicated that the prawns were able to bury more rapidly in finer than coarse sediments, thus reducing their length of exposure to predators. The implications of these findings on the current restocking program for M. dalli in the Swan-Canning Estuary are discussed