Movement patterns of Brook Trout in a restored coastal stream system in southern Massachusetts

Coastal Brook Trout (Salvelinus fontinalis) populations are found from northern Canada to New England. The extent of anadromy generally decreases with latitude, but the ecology and movements of more southern populations are poorly understood. We conducted a 33‐month acoustic telemetry study of Brook Trout in Red Brook, MA, and adjacent Buttermilk Bay (marine system) using 16 fixed acoustic receivers and surgically implanting acoustic transmitters in 84 individuals. Tagged Brook Trout used the stream, estuary (50% of individuals) and bay (10% of individuals). Movements into full sea water were brief when occurring. GAMM models revealed that transitions between habitat areas occurred most often in spring and fall. Environmental data suggest that use of the saline environment is limited by summer temperatures in the bay. Movements may also be related to moon phase. Compared to more northern coastal populations of Brook Trout, the Red Brook population appears to be less anadromous overall, yet the estuarine segment of the system may have considerable ecological importance as a food resource.     

Main stem movement of Atlantic salmon parr in response to high river temperature

Atlantic salmon become thermally stressed when water temperatures exceed 23 °C. To alleviate this stress, they behaviourally thermoregulate by moving to patches of cold water, often forming large aggregations. These patches are known as thermal refuges. Given the consensus that climate change will increase temperatures in Atlantic salmon catchments, thermal refuges will become increasingly important in minimising summer mortalities. While the behaviour of salmonids within thermal refuges is fairly well understood, less is known about their main stem movement in search of thermal refuges or its thermal and temporal cues. We detail the results of a PIT telemetry study to investigate the main stem movement behaviour of thermally stressed Atlantic salmon parr in a temperature‐impacted river. PIT antennas placed around two thermal refuges and at the upstream and downstream limits of their surrounding reach were used to record the movement of salmonids during a heatwave. We observed parr movement at the upstream and downstream antennas 135 min prior to the occurrence of the midpoint of aggregations in the thermal refuges, indicating that Atlantic salmon parr make reach‐scale movements in search of cool water prior to aggregating. Logistic regression showed that the number of degree hours >28 °C predicted the occurrence of main stem movement with a good degree of accuracy, indicating that this temperature represents a fundamental threshold causing Atlantic salmon parr to move towards cool water. Such data could be instrumental in allowing river managers to place limits on human activity within rivers, allowing salmon populations time to recover following heat stress events.     

Effects of cover crop quality and quantity on nematode-based soil food webs and nutrient cycling

Soil food webs cycle nutrients and regulate parasites and pathogens, services essential for both agricultural productivity and ecosystem health. Nematodes provide useful indicators of soil food web dynamics. This study was conducted to determine if nematode soil food web indicators and crop yield can be enhanced by combinations of cover crops in a conservation tillage system. The effects of three cover crop treatments (vetch/pea, oat/wheat and oat/wheat/pea/vetch) with low, medium and high C:N and a bare fallow control were investigated in Davis, CA. Nematode fauna, soil properties and plant productivity were measured. Soil food web indices, including the Enrichment Index (EI), Structure Index (SI), Basal Index (BI), and Channel Index (CI), based on the composition of nematode assemblages, were calculated to infer soil food web condition. Cover cropped tomato/corn rotations had twice the number of enrichment opportunist bacterial feeding nematodes, active participants in nitrogen mineralization, than fallowed tomato/corn rotations (opportunist bacterial feeders = 163 versus 98). In winter fallowed plots food webs were basal, common in disturbed, nutrient-poor conditions (BI = 37). Total number of enrichment opportunist nematodes, soil NH₄-N levels, and inferred nitrogen mineralization, were higher in cover crop treatments with low to mid C:N ratios. Omnivore and predator nematodes were scarce, averaging less than 6 nematodes 100 g^?1 in all treatments. In year one, plant productivity was highest after fallow. In contrast, in year two productivity was highest after cover crops with high nitrogen content and productivity significantly correlated with the structure of the soil fauna. Monitoring the abundance of enrichment opportunists may provide managers with a new tool to evaluate soil food web nitrogen mineralization and plant productivity.     

The source of autumn and spring downstream migrating juvenile Atlantic salmon in a small lowland river

Over 3 years, 32,444 age‐0 group Atlantic salmon (Salmo salar) parr tagged with passive integrated transponder tags throughout the River Frome catchment were assigned to one of three groups, nonmigrants, autumn migrants and spring smolts, depending on the detection and the timing of detection at downstream tag readers (situated 8.6 km above the tidal limit). We examined the effect of density at the time of tagging (n·m^?2), distance upstream from the tidal limit (km), fish length (mm), Fulton condition index, habitat type (divided into two types, main river and carrier), days after 1 September that each fish was tagged and year (replication) on the proportions of fish in each of the migration groups. Distance upstream from tidal limit was strongly negatively related to the proportion of autumn migrants and positively related to the proportion of spring smolts. Nonmigrants had a lower average body size than migrants, although there were no differences in the sizes of autumn migrants and spring smolts in September prior to migration. Fish density had no effect on migration strategy. A lower proportion of fish migrated as autumn migrants from the smaller carrier habitats than the main river channel. There is some evidence that those parr destined to become autumn migrants underwent a lower mortality rate during September before tagging than those destined to become spring migrants indicating possible physiological or behavioural differences between these two groups of fish at that time. More research into the factors responsible for initiating the autumn migration is required.     

Agronomic and physiological contributions to the yield improvement of soybean cultivars released from 1950 to 2006 in Northeast China

Increasing yield is a high priority in most breeding programs. Approximately 600 soybean cultivars had been released by the end of the last century in Northeast China. Understanding the agronomic and physiological changes is essential for planning further plant breeding strategies in soybean. In this study, 45 representative soybean cultivars, from maturity groups 00 and 0, released from 1950 to 2006 in Northeast China were compared in field conditions for 3 consecutive years. A positive correlation between seed yield and year of cultivar release was indicated with a 0.58% average annual increase. Seed number per plant was the most important contributor to yield gain, with a 0.41% increase per year. Pod number per plant and seed size varied slightly with the year of cultivar release. Although variation in protein was from 37.0% to 45.5%, and oil concentration was from 16.7% to 22.0%, their concentrations were not consistently related to year of cultivar release. A 33% increase in the photosynthetic rate, 10.6% increase in plant dry weight and 19.0% increase in harvest index (HI) were found, while leaf area index (LAI) decreased by 17.3%. Modern cultivars have higher photosynthetic rates than their predecessors. The reduced plant height gave increased resistance to lodging, with the lodging score dropping from 3.2 in 1951 to 1.0 in 2006. Seed resistances to disease and pest infestation were also improved. Yield stability was enhanced over years, which could be attributed to the stable pod production across different environments. A flow diagram to explain the contributors to genetic improvement of soybeans in Northeast China was developed.     

Products from the sensitised photo-oxidation of 2-dimethylamino-5,6-dimethylpyrimidin-4-ol

The products from the methylene blue sensitised photo-oxidation of 2-dimethylamino-5,6-dimethylpyrimidin-4-ol (I) in deuterochloroform/deuteroacetone have been investigated. A zwitterion and a hydroperoxide are formed initially, with the zwitterion predominating. The zwitterion compound degrades or reacts in the solid state on silica gel to give further products.     

Structure—activity relationships of organotin biocides and Ceratocystis ulmi

The effect of organotin compounds on the growth of Ceratocystis ulmi, the causative agent of Dutch elm disease, was studied in shake culture. Triphenyltin, (C₆H₅)₃SnX, tricyclohexyltin, (C₆H₁₁)₃SnX, and tributyltin, (C₄H₉)₃SnX, compounds were all effective in the inhibition of C. ulmi in vitro. The anionic group, X, did not play a major role in the inhibitory activities of these compounds, suggesting that the species involved in the inhibition is R₃Sn⁺ or the hydrated cation.     

Preliminary studies on the insecticidal activity and wash-fastness of twelve pyrethroid treatments impregnated into bednetting assayed against mosquitoes

The insecticidal properties of twelve pyrethroid preparations impregnated into polyester netting were compared, before and after washing, with a view to assessing their suitability for treating bednets (mosquito nets) in the field. Bioassays were carried out by exposing the mosquitoes, Anopheles gambiae Giles sensu stricto andAedes aegypti L. to netting with two concentrations of insecticide, on washed and unwashed samples, for 30 s and 3 min at different times after impregnation. Mortality was recorded after 24 h. Permethrin applied at 97°C at pH 3.4 resulted in increased uptake by polyester fibres. The performance of most insecticides on unwashed netting had not declined appreciably 12 weeks after impregnation. However, all the insecticides were depleted by washing. The treatments with best insecticidal activity after washing were cypermethrin, lambda-cyhalothrin applied at ambient temperature and normal pH and permethrin applied in a hot acid solution.     

Dislodgeable residues and persistence of diazinon,chlorpyrifos and isofenphos following their application to turfgrass

In laboratory experiments, residues of diazinon applied to turfgrass, Poa pratensis L., that could be dislodged by rubbing with cheese-cloth, declined from c. 10% of the total applied when the grass was vigorously rubbed immediately after application to 0.3% after 1 day. Sunlight did not influence the rate of decline in dislodgeable residues or residues remaining on or within the leaf blades. In field experiments where 4.5 kg ha^?1 of diazinon was applied in liquid or granular form, about 20 times more diazinon was dislodged from the liquid formulation immediately after application than from the granular. By 1 day after application the percentage of the total applied diazinon that could be dislodged was equal for both formulations. Rainfall had a significant effect on the amount dislodged from grass blades, but mowing did not. Similar rates of decline in the dislodgeable fraction of diazinon, chlorpyrifos and isofenphos were observed in field experiments. Recovery of the dislodgeable fraction declined to 0.25% or less of the total amount of any of these insecticides by 1 day after application. However, residues in the thatch remained sufficiently high for control of insects for up to 7 days after application for diazinon and 14 days for chlorpyrifos and isofenphos.     

Distribution of immune cells in the female reproductive tract in uninfected and FIV infected cats

Cell-free and cell-associated FIV effectively cross the mucosa of the feline female reproductive tract. To identify possible cellular targets of FIV and to characterize changes in mucosal immunity after infection, we examined the types and numbers of immune cells residing in the reproductive tracts of control and intravaginally FIV-infected cats. Sections of the vestibule, vagina, cervix, uterus, and ovaries, were examined by immunohistochemistry for CD4+ and CD8+ T lymphocytes, CD22+ B lymphocytes, CD1a+ dendritic cells, and CD14+ macrophages. The reproductive tract of uninfected cats contained substantial numbers of CD8+ T lymphocytes, CD4+ T lymphocytes and macrophages, as well as moderate numbers of CD1a+ dendritic cells, and few B lymphocytes. The most prominent change between FIV- and FIV+ cats was a marked decrease in the concentration of CD4+ T lymphocytes resulting in inverted CD4+:CD8+ ratios throughout the reproductive tract of infected cats. There was also a trend towards increasing numbers of CD1a+ dendritic cells in the intravaginally-infected FIV+ cats, and decreasing numbers of macrophages and CD22+ B lymphocytes. This study indicates that similar to the peripheral immune system, FIV infection is associated with CD4+ cell loss and reduced CD4+:CD8+ ratios in the female reproductive mucosal tissue.