1. Growth and reproduction of Daphnia fed lake seston were measured in two categories of meso- to eutrophic lakes differing with respect to terrestrial organic matter influence (humic and clear water lakes). The content of highly unsaturated fatty acids (HUFA), P and N, as well as the taxonomical composition of seston were analysed. 2. Seston HUFA and C : P ratios were similar between lake categories, whereas C : N ratios were lower in the clear water lakes in both spring and summer. Despite the similarity in HUFA and P content of seston, Daphnia growth rate, clutch size and the proportion of gravid females were, respectively, about 1.5, 3 and 6 times higher in the clear water lakes. 3. Differences in growth and reproduction were related to a combination of higher N content and good fatty acid quality of the seston in the clear water lakes. Relatively high biomass of edible algae, such as Rhodomonas sp. and Cryptomonas sp., in the clear water lakes, and differences in water pH likely contributed to the observed differences in Daphnia growth and reproduction between lake categories. Additionally, it is possible that Daphnia was energy limited in the humic lakes despite high particulate organic carbon (POC) concentrations, as the contribution of non-algal and detrital C to the POC pool was high. 4. Our results suggest that dietary HUFA content has the potential to improve herbivore growth and reproduction if N and P are not limiting. N merits more attention in studies of zooplankton nutrition.

To explore the perceptions of food access by African American women in Flint, MI.Using womanist theory, in which African American women's experiential knowledge centered the analysis, 8 focus groups were conducted during fall/spring, 2014–2015. Seventeen mothers aged 21–50 years with children aged <18 years and 13 women aged >60 years comprised the groups.The high cost of water, poor availability of healthy foods in inner-city stores, and limited transportation were barriers to accessing healthy food. Conversely, receiving food from food giveaways, friends, and family, as well as access to transportation facilitated food access. These women also reported discriminatory experiences and diet-related health concerns. Participants were keenly aware of available free community resources and gender, racial, and income barriers to accessing them.Understanding these barriers and facilitators provides information to aid local food policy assistance decisions and inform community-based interventions, especially given the lead contamination of water and the purported importance of a healthy diet to sequester lead.

Food composition of Abramis brama was studied in the shallow, meso-eutrophic Hamry reservoir (Czech Republic). Fish were sampled during the daytime in the pre-spawning period (April), the post-spawning (June), summer (July) and autumn (October) in 2011. The bream sampled comprised two main size groups: small (124-186 mm) and large (210-315 mm) standard length. Twenty specimens of each size group (except April - 40 large fish) were taken for analysis on each sampling occasion. Food composition was evaluated using gravimetric methods. Over the whole season, detritus and aquatic vegetation were the dominant dietary items taken. During summer, the diet of large bream comprised mainly aquatic vegetation. Benthic macroinvertebrates and zooplankton formed a minor part of bream diet over the whole season. Specific food habits of bream could be explained by specific conditions within the reservoir and available food resources.

A case study in the Solukhumbu region in northern Nepal reveals that the high number of seasonal tourists—which has doubled in 20 years—has led to growing water, food, and energy demands that have modified agropastoral practices and the use of local resources. This has induced new patterns in the movement of goods, people, and animals in the Everest region and the reconfiguration of the water–energy–food nexus. We use this concept of nexus to analyze ongoing interactions and transformations. Key changes involve (1) massive imports of consumer goods; (2) use of local resources with new techniques (hydropower plants, improved mills, greenhouses, and pipes for domestic networks) that depend on imported materials, which are newly accessible to Sherpas as a result of economic benefits generated by tourism; (3) commodification of local resources (water, hydropower, vegetables, fodder, and flour); (4) an increasing number of electrical appliances; and (5) new uses of water, especially for tourist-related services, including hot showers, watering of greenhouses, bottling of water, and production of electricity for cell phones, rice cookers, and other electric appliances. These new uses, on top of traditional ones such as mill operation, compete in some places during spring when water supplies are low and the tourist demand is high. A transfer of pressure from one resource (the forest) to another (water) has also resulted from the government ban on woodcutting, incentives to develop hydropower, and the competition between lodges to upgrade their amenities by offering better services (such as hot showers, plugs to recharge batteries, internet connections, and local vegetables). Our research finds that water is now central to the proper running of the tourist industry and the region's economy but is under seasonal pressure.

It is well known that immune defenses of bivalves against environmental and pathogenic stresses are primarily attributable to hemocytes. Hemocyte parameters are being used progressively as indicators to assess the host immune status. Moreover, there is increasing evidence that seasonal variations on the immune status have two origins: exogenous and endogenous. In this work, we investigated the effects of seasonal exogenous (water temperature and food availability) and endogenous (size and reproduction) factors on the hemocyte parameters in the scallop Chlamys farreri. Scallops were monthly collected from February to December 2009 at 2 sampling sites differing in culture mode: Qingdao for monoculture and Weihai for scallop—kelp polyculture. Six hemocyte parameters including total hemocyte count (THC), granulocyte percentage (GP), intrahemocytic phenoloxidase (PO), acid phosphatase (ACP), superoxide dismutase (SOD), and peroxidase (POD) were analyzed. Results illustrated that all hemocyte parameters exhibited marked seasonal variations, following a similar pattern at both sites. High values of THC, GP, PO, and POD were observed in spring and early summer, a period of favorable water temperature and high food availability and gonad index, whereas low values were found in summer and early autumn, a period corresponding to reproduction completion and high water temperature. Moreover, SOD was lowest in February and highest in August, and correlated positively with water temperature. Hemocyte parameters in the scallop C. farreri varied greatly among seasons, and their values were generally low during summer and early autumn, suggesting that scallops had a depressed immune status during this period.

The present paper reports on the results of a long-term field study on the simultaneous influence of 2 environmental factors (temperature and food supply) on annual growth rates in the tellinid bivalve Macoma balthica. For >30y (1978–2009) we monitored twice-annually the weight changes of soft parts of individuals of known age at several permanent sampling stations located at Balgzand, an extensive (50km2) tidal flat area in the western Dutch Wadden Sea. Monthly data were available on mean water temperature and chlorophyll a (chl a) concentration from a nearby site in the main tidal inlet. Mean individual ash-free dry weights at ages of nearly 1 and of nearly 1.5y were assessed in February/March and in August, respectively. Such weights show a consistent annual pattern: they increase between late winter and early summer to decline for the remainder of the year. Annual multi-station means of the spring/summer individual weight gains were higher as chl a concentrations in the water had been higher and water temperatures had been lower for the growing season. These correlations proved to be stronger at sampling sites that were situated low in the intertidal zone close to the main tidal stream than at those high in the intertidal near the coast (where M. balthica obtain their food primarily by deposit feeding on benthic material). At the low off-shore sites, suspended algae are available for longer daily periods and their concentrations in flood water may be less depleted by grazers. The negative correlation between weight gain and water temperature may have been primarily based on the shortening of the M. balthica growing seasons in warm summers. We conclude that the present simultaneous trends of global warming and declining stocks of pelagic algae may affect M. balthica in the Wadden Sea in a similar, negative, way.

Only a combination of nutrient load abatement and food-web management proved efficient for the management of water quality in the deep stratifying Wupper Reservoir. Reduction of nutrient loading, was completed in winter 1992/1993, but resulted only in reduced winter/spring mixing of phosphorus concentrations. Since the capacity of the diatom spring bloom to remove nutrients from the trophogenic layer of this slightly eutrophic water-body was never exhausted, the surplus of total phosphorus available to support summer algal growth remained unchanged. Thus, nutrient reduction alone did not improve the water quality, as expected. Subsequent replacement of the smaller Daphnia cucullata by the larger Daphnia galeata-hyalina complex that was attributable to successful food-web management did, however, result in a shift from a turbid to a clear water regime in 1999. Clearly, the zooplankton community, and therefore food-web structure, played an integral role in nutrient recycling and in the repartitioning of the phosphorus pool. As diatom settling and grazing became much more tightly linked with the appearance of the larger-bodied Daphnia galeata-hyalina complex, which exploits lower-level food resources as early as May, daphnids increasingly acted as a sink for phosphorus. This increased export fluxes out of the pelagic zone and leaves a smaller surplus of total phosphorus to support the accumulation of summer algae. Consequently, water transparency and total chlorophyll concentrations in summer improved with food-web restructuring, indicating real oligotrophication of Wupper Reservoir driven by internal feedbacks.

Brent geese Branta bernicla spring fattening around Agerø, Denmark, alternate between feeding on saltmarshes and submerged Zostera beds in Limfjorden. It appeared from field observations that these alternations depended on the water level in Limfjorden. A model was developed to assess the impact of water level fluctuations on the habitat use. A second model was developed to estimate the impact of water level on Zostera availability. The first model was successful in demonstrating that fluctuations in water levels had considerable influence on habitat use by the brent geese, i.e. they fed on Zostera at low water levels and on saltmarshes during high water levels, particularly so in early spring, and that the switch between habitats occurred within a narrow water level span of ca 30 cm. The second model demonstrated that the switch between habitats could be explained by lowered availability of Zostera as water levels increased. By combining the output from the two models, differences between years could partly be explained by differences in Zostera availability in the early spring period (21 March ‐ 25 April), whereas a more complicated situation was detected later in spring (26 April ‐ 31 May). The models presented may be considered as tools in investigations of habitat use and carrying capacity of seagrass beds in non‐tidal areas, where birds' access to feeding areas regularly may be hindered by high water levels.

Food processing waste waters at two irrigated land disposal sites and subsurface waters (perched and ground waters) were monitored at daily to monthly intervals over one annual cycle of production. Soil profiles were sampled to depths up to 6.6 m in the early fall. Yearly inputs were calculated at 487 kg/ha total N (Kjeldahl plus NO³-N) and 101 kg/ha soluble PO₄-P (orthophosphate) from cannery wastes at site 1. Estimates for milk wastes at site 2 were 562 kg/ha total N and 522 kg/ha PO₄-P. The range for NO₃-N in subsurface waters was 7 to 16 ppm at site 1 (perched water at 1.5 m) and 2 to 41 ppm at site 2 (ground water at 0.9 m). Maximum concentrations, found in summer, were essentially the same as the average for total N in the input wastes (16 ppm at site 1 and 38 ppm at site 2). Nitrate was stable in the percolation stream below the root zone. Annual additions to subsurface waters were estimated at 76% of input N at site 1 and 65% at site 2. The range of PO₄-P in subsurface waters was 0.5 to 1.5 ppm at site 1 and 0.04 to 1.8 ppm at site 2; average waste water concentrations were 3 and 35 ppm. The highest concentrations in subsurface water were found in spring. Annual subsurface discharge was estimated at 27% of input P at site 1 and 2% at site 2. The extensive removals of PO₄ and the similar concentrations encountered in subsurface waters are of theoretical and practical interest since PO₄-P had already accumulated in soil profiles at both sites in quantities which exceed the Langmuir maxima for nonirrigated control soils. During seasons of major irrigation input, NO₃ appeared in subsurface waters in concentrations exceeding public health standards; PO₄ concentrations exceeded environmental guidelines at all times except where irrigation was discontinued during the winter at site 2. Soil systems appeared poised to discharge at the observed rates because of the large quantities of organic N and fixed P which had accumulated in the profiles over 20 years operation at site 1, and 10 years at site 2. The rate of residual accumulation in soil could have been reduced by harvest, to extend system life materially. The harvest potential of three grass clippings per season removed for silage, was estimated experimentally at 31% of input N at both sites and 80% of input PO₄ at site 1; 27% at site 2.

Wild Atlantic salmon smolts were captured during spring out-migration in the Northwest Miramichi River, New Brunswick, Canada, and placed on an isotopically distinct hatchery diet to determine the relative contributions of growth and metabolic turnover to isotopic change. As expected for an ectothermic species, growth explained a large amount of isotopic variation in changing stable carbon ratios of muscle tissue (average r ²= 0.46) for the 3 years of study. Turnover rates of muscle carbon in all 3 years in growing fish (0.24–0.66 month⁻¹) were higher than previously reported values for other ectothermic species, but there was little evidence for isotopic change in non-growers (average r ²= 0.041, p > 0.1). It is unlikely that non-growers had consumed any of the hatchery diet over a 2-month period, thus preventing them from acquiring the new carbon isotopic signature. This period of food deprivation resulted in nitrogen-15 enrichment in liver relative to muscle (p= 0.003). It is advised that future isotope studies of metabolic turnover rates in ectotherms be conducted on slow-growing animals over a long time period. This would serve to avoid the obscuring effects of growth on isotopic change, and provide stronger comparisons to endothermic tissue turnover rates.