Variation in prey selection and foraging success associated with early‐life ontogeny and habitat use of American paddlefish (Polyodon spathula)

Many fishes are planktivorous during early life and switch to piscivory or consume larger food items as ontogeny progresses. In contrast, paddlefish start as particulate feeders and later become filter feeders. Few studies have identified food items essential for paddlefish growth, survival and recruitment surrounding this ontogenetic diet shift. The objectives of this study were to investigate (i) prey types consumed by paddlefish, (ii) variability in prey selection surrounding an ontogenetic diet shift and (iii) whether habitat affected paddlefish prey selection or foraging success. We analysed gut contents of 189 wild age‐0 paddlefish from the middle Mississippi River (MMR) and also conducted a laboratory experiment to address these objectives. We found that paddlefish primarily foraged on benthic macroinvertebrates in the MMR, which differed from previous studies in lentic systems, suggesting young paddlefish prey selection may be labile depending on habitat (i.e., lotic versus lentic). Dominant prey of wild‐caught and experimental age‐0 paddlefish were caddisfly larvae (Trichoptera), followed by hemipterans and amphipods. We found little evidence that habitat attributes affected foraging success, but the most common prey items consumed were associated with wing dike habitat and the upstream and downstream tips of alluvial islands. Our experimental study revealed that if provided a mixture of organisms, age‐0 paddlefish will primarily consume macroinvertebrates while age‐1 paddlefish will mainly filter zooplankton. Overall results suggest young paddlefish prey selection can be highly variable, but also heavily reliant on a narrow group of prey resources.     

Thirty years of change and the future of Alaskan fisheries: Shifts in fishing participation and diversification in response to environmental,regulatory and economic pressures

Heterogeneity in human responses and decision‐making can contribute to the resilience of social–ecological systems in the face of environmental, political and economic pressures. In fishery systems worldwide, the ability of harvesters to maintain a diverse portfolio of fishing strategies is important for building adaptive capacity. We used a case‐study approach to examine the complexity of factors that inhibit or promote diversification in fisheries of Alaska, one of the major fishing regions of the world. Through a combination of harvest records and literature review, we explored shifts in participation and portfolio diversity in Alaskan fisheries over three decades. The four case‐studies examined the responses of fishers, fleets and communities to multiple, intersecting pressures, including biological declines, market and price dynamics, fishery privatization and the 1989 Exxon Valdez oil spill. These cases illustrate how stressors acting at multiple scales can encourage or constrain opportunities for diversification, and that these opportunities may be spread inequitably across participants. Overall, we found evidence for reduced participation and increasing specialization in Alaskan commercial fisheries. While numerous factors explain these trends, policies like individual quota systems and the increasing cost of entry into fisheries are forcing consolidation at local to regional scales. A portfolio approach to managing fisheries that reduces barriers to diversification and includes broad representation of resource users and communities in management may help to maintain opportunity and choice for fishers.     

The effect of salinity on corn yield using the CERES-maize model

In most cases, when calculating soil water availability, only thewater content is considered. The effect of salinity on the wiltingpoint is neglected. The objective of this work is to use asimulation model (CERES-maize) in order to predict cornyields as a function of water salinity under severalenvironmental, agrotechnical, and plant characteristics. A modelis presented in which the wilting point is a function of the soilsalt content. At high salinity, the water content at wilting pointis higher than at low salinity, resulting in an insufficient amountof available water and, therefore, a reduced yield. The modelwas used to simulate several theoretical and experimentalsituations for forage corn and grain corn. Simulation resultsshowed that nitrogen fertilization increases the salinity thresholdvalue and the yield sensitivity (rate of yield reduction per unitof salinity). The also showed that forage corn is more sensitiveto salinity than grain corn. If the soil is not leached, a heaviersoil texture has a higher salinity threshold value. On the otherhand, if the soil is leached, the soil texture has no influence onthe salinity threshold value and the yield is less sensitive tosalinity in sandy soils. The determination coefficient (r²= 0.75) indicated that the results of the simulations were in goodagreement with the field data.     

Simulated water and solute distribution from a crossed triple line-source

Summary Multivariable irrigation experiments are usually expensive and seldom cover the whole range of desired values. The crossed triple line-source (CTLS) was designed to provide a relatively simple and inexpensive irrigation system for creating continuous gradients of more than one variable. A computer model was developed to assist in evaluating the continuously changing multivariable levels, produced by the CTLS, given various inputs. A single sprinkler's distribution function was used in the model's development. The results of the overlapping sprinkling patterns are calculated throughout the experimental area for water depth, salinity level, and Nitrogen concentration. Measured values of irrigation water electrical conductivity (EC_i) and Nitrogen concentration were in good agreement with predicted values.     

Race and food store availability in an inner-city neighbourhood

BACKGROUND: A growing body of research has shown that disparities in resources, including food stores, exist at the neighbourhood level and the greatest disparities are seen in minority neighbourhoods, the same neighbourhoods at increased risk of obesity and diabetes. Less is known about whether differences in availability of resources by African American or Latino race/ethnicity exist within a single minority community. OBJECTIVE: The present study examined whether census blocks either 75% African American (AA) or 75% Latino (L) are associated with food store availability, as compared with racially mixed (RM) census blocks, in East Harlem, New York. DESIGN/METHODS: A cross-sectional study utilising a walking survey of East Harlem was performed. Food stores were classified into: supermarkets, grocery stores, convenience stores, specialty stores, full-service restaurants and fast-food stores. RESULTS: One hundred and sixty-five East Harlem census blocks were examined; 17 were AA, 34 were L and 114 were RM. Of AA census blocks, 100% had neither supermarkets nor grocery stores. AA census blocks were less likely to have convenience stores (prevalence ratio (PR) = 0.25, 95% confidence interval (CI) 0.07-0.86) compared with RM census blocks. In contrast, predominantly L census blocks were more likely to have convenience stores (PR = 1.8, 95% CI 1.20-2.70), specialty food stores (PR = 3.74, 95% CI 2.06-7.15), full-service restaurants (PR = 1.87, 95% CI 1.04-3.38) and fast-food restaurants (PR = 2.14, 95% CI 1.33-3.44) compared with RM census blocks. CONCLUSIONS: We found that inequities in food store availability exist by race/ethnicity in East Harlem, New York. This has implications for racial/ethnic differences in dietary quality, obesity and obesity-related disorders.     

Health and growth performance of the blue mussel (Mytilus edulis L.) from two hanging cultivation sites in the German Bight: a nearshore—offshore comparison

The health of cultivated blue mussels from an offshore and a nearshore sites was compared by assessing lysosomal membrane stability (LMS) and accumulations of lipofuscin and neutral lipids in the digestive glands. In addition, the condition index, parasite infestation rates, growth performance and energy status of the mussels were assessed during 10?months of sampling. Abiotic and biotic site characteristics were investigated by water analysis for each sampling cycle. Further, data of contaminant loads of the softbody and pollutant concentration of the water column, suspended particles and sediments from both sites were analysed. Results show that positive offshore effects due to dilution of contamination were not evident for all parameters analysed. Condition indices were high, and parasites were not present in offshore mussels. In contrast, the integrative health parameter LMS and growth performance were slightly, but not significantly, better in the nearshore cultivated mussels. These findings correspond with the higher contaminant concentrations in the softbodies of mussels and the water column from the offshore testing site. Both sites showed low LMS values and high accumulations of lipofuscin and neutral lipids, indicating that environmental conditions in the German Bight are generating stress for blue mussels even in the offshore areas. Exposure to fluvial transport points to a comparable probability for high contamination loads similar to nearshore areas. We therefore recommend adding a minimum salinity threshold to the definition of offshore aquaculture to exclude areas under fluvial influence.     

Genetic architecture of plant height in maize phenotype‐selected introgression families

This study aimed at developing, characterizing and evaluating two maize phenotypic‐selected introgression libraries for a collection of dominant plant height (PHT)‐increasing alleles by introgressing donor chromosome segments (DCS) from Germplasm Enhancement of Maize (GEM) accessions into elite inbred lines: PHB47 and PHZ51. Different backcross generations (BC₁‐BC₄) were developed and the tallest 23 phenotype‐selected introgression families (PIFs) from each introgression library (PHB47 or PHZ51) were selected for single nucleotide polymorphism genotyping to localize DCS underlying PHT. The result shows that most PIFs carrying DCS were significantly (α = 0.01) taller than the respective recurrent parent. In addition, they contained larger donor genome proportions than expected in the absence of selection or random mating across all BC generations. The DCS were distributed over the whole genome, indicating a complex genetic nature underlying PHT. We conclude that our PIFs are enriched for favourable PHT‐increasing alleles. These two libraries offer opportunities for future PHT gene isolation and allele characterization and for breeding purposes, such as novel cultivars for biofuel production.     

Weathering and mobility sequence of minor elements on a basaltic pedomorphic surface,Galilee, Israel

A number of minor elements was determined in 21 samples of several soil profiles of a young pedomorphic surface on basalt, Upper Galilee, Israel, ranging from red basaltic Lithosols to lithic Red Mediterranean soils and montmorillonitic Grumusols (Xerorthents, Lithic Xerochrepts, and Chromoxererts).Strontium and to a lesser extent barium are lost during the weathering of the feldspars; Sr continues to be leached out on the slope. Titanium concentrates in the non-clay residue and follows iron during its redistribution on the slope. Manganese is more mobile than iron. Cobalt is partially correlated with manganese, but like Ni, Cr, Cu and V, these elements do not show any definite trend and appear to be rather immobile under the moderate weathering conditions of the Mediterranean environment where montmorillonite is the major clay mineral.     

Mechanism of action and effects of repartitioning substances for swine fattening

The effect of an application of pST- and beta-agonists on the fattening-capacity and carcass-composition of the pig is evaluated by means of data available in literature. American stress-resistant cross-bred pigs show a stronger reaction on pST in their fattening-capacity than European breeds. Obviously, this has derived from genetic differences. Feed-utilization, meat-gain, and reduction of lipid content in the case of European breeds are, nevertheless, subject to a pronounced improvement through pST and beta-agonists. Further positive aspects are the decrease of the N-excretion in urine and no, resp. only minor influence on the quality of meat. A negative aspect of the meat with regard to consumers' acceptance is the fact that the mentioned substances belong to the group of hormones.     

Juvenile Pancreatic Atrophy in Greyhounds: 12 Cases (1995–2000)

Background: This study describes compound failure of the endocrine and exocrine pancreas in Greyhounds, a condition that has not been reported in the veterinary literature.
Objective: To describe the clinical and pathologic findings in 12 Greyhounds with juvenile pancreatic atrophy.
Animals: Ten Greyhounds presented for necropsy examination and 2 sibling Greyhounds presented for clinical evaluation before necropsy, all with a history of small-bowel diarrhea.
Procedures: Retrospective study of laboratory and pathologic findings in 12 Greyhounds, including serum trypsin-like immunoreactivity assays, oral glucose tolerance testing, and serum anti-insulin antibody concentrations.
Results: Gross pancreatic atrophy was found in all 12 dogs. Histopathologic lesions were found in both the endocrine and exocrine pancreas and included acinar cell apoptosis, zymogen granule loss, cytoplasmic clearing or vacuolar change, lobular atrophy, islet loss, and lymphocytic or lymphoplasmacytic pancreatitis. Antemortem test results on the 2 Greyhound puppies indicated concurrent exocrine pancreatic insufficiency (EPI) and insulin-dependent diabetes mellitus (IDDM).
Conclusions and Clinical Importance: Compound failure of the exocrine and endocrine pancreas is rarely reported in dogs and neither disease is well recognized in the Greyhound. This condition is of potential economic importance to the Greyhound racing industry.