Comparison of spatial distribution models to predict subtidal burying habitat of the forage fish Ammodytes personatus in the Strait of Georgia,British Columbia,Canada

1. The Pacific sand lance (Ammodytes personatus) is a key forage species for many commercially important fish (e.g. salmon and groundfish), marine birds, and whales found in nearshore coastal waters of British Columbia, Canada.
2. Sand lance lack a swim bladder and have a requirement for low-silt, medium-coarse sandy sea-bed habitat for burying. Little information is available describing the distribution of burying habitat, partly because there are no commercial fisheries for A. personatus in British Columbia.
3. This information is required by habitat and wildlife managers to identify and protect uncommon patches of burying habitats from detrimental activities, including dredging, infilling, and oil spills.
4. In this study, habitat distribution results from five suitability modelling algorithms were evaluated: maximum entropy, generalized linear model, generalized additive model, random forest, and an ensemble model of the latter three.
5. The maximum entropy model had the highest performance score (area under the receiver operator characteristic curve was 0.78) and was selected as the model that most accurately identified the presence of suitable A. personatus burying habitat.
6. Model results indicate that suitable burying habitat is primarily influenced by derived sea-bed substrate, distance to estuary, distance to sand-gravel beaches, and bottom sea temperature.
7. Overall, the spatial modelling identified only 105 km² of highly suitable sand lance burying habitat, or 2.6% of the study area (0–150 m), primarily in Haro Strait, along the east coast of Vancouver Island, and in northern regions of the strait near Cortes, Savary, and Harwood islands.
8. Identification of this uncommon and patchy burying habitat will contribute to the ongoing conservation of an important coastal prey species.

     

Assessing Market Potential of Agroforestry Tree Seedlings in Western Kenya

In this study, Porter’s framework is used to analyse the forces that coordinate and control the market for agroforestry tree seedlings in the Nyando basin in Western Kenya where smallholder farmers were assisted by non-governmental and research organisations to start tree seedling nurseries, with a view to fostering adoption of agroforestry in the region. In addition, financial viability of the enterprise is assessed and the resources and interventions required to improve the operators’ competitiveness and make the enterprise sustainable are identified. Primary data collected from eight nursery operators and sixty agroforestry farmers are used and supplemented with secondary information obtained from relevant literature to gain an insight into the tree seedling industry within and outside the region. The results indicate that the tree seedling industry is highly competitive and is characterised by several small-scale operators who employ similar strategies and produce and sell nearly homogenous products. Consequently, competition is based on price rather than on strategies that require capital investments such as branding, product differentiation and product promotion. The enterprise is financially viable but the gross margins, particularly those of timber tree seedlings, are sensitive to low seedling prices suggesting that competitors are exerting pressure on prices and profitability. Thus, to gain an edge over the competitors, the small-scale operators need to build competitive advantage by adopting strategies that allow them to charge higher prices for their products, maintain customer brand loyalty and understand the coordination, control and relationships within the industry.     

Antioxidant and antiproliferative activities of heterofucans from the seaweed Sargassum filipendula

Fucan is a term used to denominate a type of polysaccharide which contains substantial percentages of l-fucose and sulfate ester groups. We obtained five heterofucans from Sargassum filipendula by proteolytic digestion followed by sequential acetone precipitation. These heterofucans are composed mainly of fucose, glucose, glucuronic acid, galactose and sulfate. These fucans did not show anticoagulant activity in PT and aPTT tests. Their antioxidant activity was evaluated using the follow tests; total antioxidant capacity, scavenging hydroxyl and superoxide radicals, reducing power and ferrous ion [Fe(II)] chelating. All heterofucans displayed considerable activity, especially SF-1.0v which showed the most significant antioxidant potential with 90.7 ascorbic acid equivalents in a total antioxidant capacity test and similar activity when compared with vitamin C in a reducing power assay. The fucan antiproliferative activity was performed with HeLa, PC3 and HepG2 cells using MTT test. In all tested conditions the heterofucans exhibited a dose-dependent effect. The strongest inhibition was observed in HeLa cells, where SF-1.0 and SF-1.5 exhibited considerable activity with an IC50 value of 15.69 and 13.83 μM, respectively. These results clearly indicate the beneficial effect of S. filipendula polysaccharides as antiproliferative and antioxidant. Further purification steps and additional studies on structural features as well as in vivo experiments are needed to test the viability of their use as therapeutic agents.     

Spatio-temporal distribution of mutton snapper and dog snapper spawning aggregations in the South-west Atlantic

1. Sites and periods of spawning aggregations of two important fishery resources, the mutton snapper, Lutjanus analis, and the dog snapper, Lutjanus jocu, were identified and validated along the Brazilian north-east coast (latitude 8–15°S) using exploratory analysis of catch per unit effort (CPUE) data, gonadosomatic index analysis, and gonad histology.
2. The CPUE analysis for both species allowed the identification of outliers and far outliers, representing fisheries with exceptional catches, which were used as proxies of possible aggregation.
3. The presence of pre-spawning and recent spawning signs (hydrated oocytes and post-ovulatory follicles) in the ovary of females caught at sites with recurrent records of high CPUE allowed the validation of spawning activity at those specific sites for each species. All aggregation sites identified in this study were located on the outer shelf, close to the shelf break, a region that has been declared an Ecologically and Biologically Significant Marine Area.
4. Comparison of two subregions showed significant differences in size structure of the fish sampled during landings, suggesting a fishing depletion effect in the north region.
5. For both species, reproduction peaked twice in all regions studied, with a more marked peak during summer. However, spawning activity was observed in almost every month of the year, suggesting that seasonal closures could be more effective if combined with spatial measures.
6. In the northern part of the study range, spawning grounds were found to lie just outside the boundaries of one of Brazil's largest marine protected areas. Inclusion of those grounds in the marine protected area would increase protection of these species and also mean increased protection of an Ecologically and Biologically Significant Marine Area, encompassing mesophotic reefs.
7. The identification of these spawning aggregations sites on the north-east coast of Brazil was conducted in collaboration with local fishers that traditionally use bottom handline. Co-management approaches are suggested in view of the importance of these fishing sites for traditional fishing communities that may also face threats due to encroachment of mobile fleets.