Evaluating methods for identifying large mammal road crossing locations: black bears as a case study

Landscape Ecology - Roads have several negative effects on large mammals including restricting movements, isolating populations, and mortality due to vehicle collisions. Where large mammals...     

Nutritional and mineral content of prickly pear cactus: A highly water‐use efficient forage,fodder and food species

Increased demand for food requires us to investigate livestock forage and fodder crops that can be grown over a wide range of locations where their cultivation will not compete with that of the food supply. A large portion of the southwestern United States consists of underutilized semi‐arid land. Crops typically used for livestock fodder or forage have high‐water demands that make them uneconomical or unsustainable for semi‐arid and arid regions. The growth rate and low‐input requirements of prickly pear cactus (Opuntia ficus‐indica) make it an excellent candidate for forage or fodder supplementation or replacement in these regions. Previous reports about forage quality data on Opuntia have been scattered across multiple locations, growing conditions and cultivars. Here, we report on the forage quality and mineral content of Opuntia ficus‐indica grown under both field and greenhouse conditions. Crude protein was 71 and 264 g/kg of dry mass for field and greenhouse conditions, respectively. Field‐grown plants showed higher acid and neutral detergent fibre content than greenhouse‐grown plants reflecting higher cellulose, hemicellulose and lignin accumulation. Nutritional values were also compared to requirements of cattle to determine what deficiencies might need to be addressed through supplementation. These data suggest that Opuntia can be used in combination with other feed sources to reduce the demand of resource‐intensive forage crops for raising livestock in dryland areas.     

Use of reflex indicators for measuring vitality and mortality of the snow crab (Chionoecetes opilio) in captivity

The snow crab (Chionoecetes opilio) is one of the most important commercial crabs in the world; it is heavily exploited in Atlantic Canada, Alaska, the Sea of Japan and the Barents Sea. Catches in the Barents Sea north of Norway have increased dramatically in the last decade. Most of the world's catch is processed, frozen and exported overseas. However, recently there has been considerable interest in exporting live snow crab, particularly in Norway. The stress of capture and live transport can result in significant mortalities. In order to establish a live export industry for snow crab, the welfare of the animal must be monitored throughout all the steps of the live transport process. In this study the reactions of snow crabs exposed to increasing periods of air exposure were measured in terms of reflex indicators, incidence of mortality, blood lactate levels and blood protein and haemocyanin. Although this is not a specific live holding or live transport process the aim was to test the suitability of reflex indicators to reflect vitality (stress) and not just to predict mortality. This would be compared with traditional blood biochemistry techniques for measuring crustacean stress. The study demonstrated that the reflex index score (RIS) is suitable to assess the vitality of snow crab. Longer air exposure periods render higher mortality rates and less vital individuals. The authors believe using vitality reflex indicators would be a suitable way of measuring crab welfare during the live holding and transport process.     

Linking size‐based trophodynamics and morphological traits in marine fishes

The rule of thumb in marine trophodynamics indicates that the bigger an organism, the higher its trophic level (TROPH). This generalization leads to the assumption that fishes increase their TROPH with growth. However, a recent review showed that for many species, TROPH does not increase with body size, suggesting that size‐independent feeding is not rare in marine fishes. Here, we assessed some morphological traits of marine fishes that could potentially be used as indicators for the ability to vary TROPH with body size. Stable isotope values of nitrogen were used as a proxy TROPH. The specific objectives were as follows: (a) to evaluate the relationship between the oral gape and the trophodynamic trend and (b) to quantify the relevance of 11 external morphological traits in determining the size‐based trophodynamics. We used random forest models to identify the morphological traits that would help predict which species would have the potential to increase TROPH with growth and which would have not. The selected traits included the pelvic fin relative position, the dorsal fin shape, total length, and relative mouth size. Our results also showed a marked relationship between the rate of increase in the oral gape and TROPH. The analyses presented here provide the first comprehensive and quantitative review aiming at linking the trophodynamics of marine fishes with external morphological traits.     

Pre‐Columbian fisheries catch reconstruction for a subtropical estuary in South America

Small‐scale fisheries provide food and livelihoods for thousands of people along the Brazilian coastline. However, considerable uncertainties still surround the extent to which artisanal and subsistence fisheries contribute to the total of national landings and their historical ecological significance. Fisheries monitoring is deficient in Brazil, and historical records are limited to irregular accounts spanning the last few decades, while this coastline has supported human populations for at least 6,000 years. Here, we estimate pre‐Columbian subsistence catches for a large subtropical estuary in southern Brazil. Our results suggest that prehistoric populations may have extracted volumes of fish biomass higher than or comparable with historical subsistence fisheries in the region, and that the latter is likely underestimated. If a long‐term perspective is required to evaluate the current economic value and status of fisheries in subtropical and tropical South America, this should go beyond the historical time interval and integrate the contribution of pre‐Columbian archaeology.     

Effects of Corbicula fluminea on the nutrient concentration and phytoplankton biomass of tropical reservoirs

International Aquatic Research - Invasive bivalves are known to negatively impact aquatic ecosystems across the globe. Previous research has demonstrated invasive bivalves can shift nutrients from...