The aim of this study was to analyze the influence of organic fertilizer on the availability of natural food (plankton and benthos) and water quality. Two fertilization protocols were adopted using inorganic and organic fertilizers with shrimp (stocked treatment) and their controls (unstocked treatment). Experimental units consisted of 12 circular fiberglass tanks (500 l) with estuarine sediment, individual aeration and no water exchange. In stocked treatments were used 40 juveniles/m², and they were fed with 35% crude protein marine shrimp ration, three times a day. Under the organic fertilization protocol, the plankton showed higher abundance of Nitzschia and rotifers, the phytobenthos consisted mainly of Nitzschia, Amphiprora and Oscillatoria, the epibenthos was represented mainly by nematodes and rotifers, and the macro-invertebrates were mainly oligochaetes. In relation to inorganic fertilization, the plankton was represented mainly by Coscinodiscus and rotifers, the phytobenthos consisted mainly of Amphiprora and Oscillatoria, the epibenthos was represented mainly by nematodes and rotifers, and the macro-invertebrates were mainly oligochaetes. Dissolved oxygen was higher for organic fertilizer (6.16 ± 0.98 mg/l) than for inorganic (5.92 ± 1.19 mg/l) while the other water quality parameters did not present significant differences. Survival was similar in the two fertilization regimes (96.6%). Final body weight was 11.89 ± 1.73 g for the inorganic fertilizers and 12.28 ± 1.71 g for organic fertilizer. It is concluded that wheat bran showed good performance in the water quality without exchange, in the availability of natural food, and in the growth and survival of the shrimps in the microcosms.

For the removal of nutrients from eutrophic stream water polluted by non-point sources, an artificial aquatic food web (AAFW) system comprising processes of phytoplankton growth and Daphnia magna grazing was developed. The AAFW system was a continuous-flow system constructed with one storage basin of 3 m³ capacity, one phytoplankton tank of 3 m³ capacity, and one zooplankton growth chamber of 1.5 m³ capacity. The system was optimized by setting hydraulic retention time of phytoplankton tank as 3 days and D. magna density as 740-1000 individual l⁻¹. When the system was operated on eutrophic stream water that was delivering 471 g of total nitrogen (TN) and 29 g of total phosphorus (TP) loadings for 45 days, 250 g (53%) of TN and 16 g (54%) of TP were removed from the water during its passage through the phytoplankton tank. In addition, 64 g (14%) of TN and 4 g (13%) of TP were removed from the water by harvesting zooplankton biomass in the zooplankton growth chamber, resulting in significant overall removal rates of TN (69%), nitrate (78%), TP (73%), and dissolved inorganic phosphorus (94%). While the removal efficiency of the AAFW system is comparable to those of other ecotechnologies such as constructed wetlands, its operation is less limited by the availability of space or seasonal shift of temperature. Therefore, it was concluded that AAFW system is a highly efficient, flexible system for reducing nutrient levels in tributary streams and hence nutrient loading to large aquatic systems receiving the stream water.

This is the first volume on the proceedings of the national conference on ‘Water for Food and Environment’, which was held from June 9–11, 2009 at the Bandaranaike Memorial International Conference Hall (BMICH). The volumes two and three have been produced as separate documents of this report series. In response to a call for abstracts, 81 abstracts were received from government institutes dealing with water resources and agriculture development, also from universities, other freelance researchers and researchers from the International Water Management Institute (IWMI).Forty Seven of the eighty-one abstracts that were submitted were accepted for compiling full papers.In the past couple of years the sharp increase in food prices worldwide has raised serious concerns about food security, especially in developing countries. To effectively address these concerns a holistic approach is required that encompasses improved agricultural water productivity, adaptation to climate change, targeted and appropriate institutional and financial measures, and a consideration of environmental issues. The main purpose of the conference was to share experiences in these areas and to find opportunities to improve farmers’ incomes and food production, and to promote environmentally sustainable practices in Sri Lanka in the face of growing water scarcity and the challenges of climate change.

This is the first volume on the proceedings of the national conference on ?Water for Food and Environment?, which was held from June 9?11, 2009 at the Bandaranaike Memorial International Conference Hall (BMICH). The volumes two and three have been produced as separate documents of this report series. In response to a call for abstracts, 81 abstracts were received from government institutes dealing with water resources and agriculture development, also from universities, other freelance researchers and researchers from the International Water Management Institute (IWMI). | Forty Seven of the eighty-one abstracts that were submitted were accepted for compiling full papers. | In the past couple of years the sharp increase in food prices worldwide has raised serious concerns about food security, especially in developing countries. To effectively address these concerns a holistic approach is required that encompasses improved agricultural water productivity, adaptation to climate change, targeted and appropriate institutional and financial measures, and a consideration of environmental issues. The main purpose of the conference was to share experiences in these areas and to find opportunities to improve farmers? incomes and food production, and to promote environmentally sustainable practices in Sri Lanka in the face of growing water scarcity and the challenges of climate change.

Juvenile Pacific abalone (Haliotis discus hannai Ino) are currently reared in land‐based aquaculture systems until they reach the necessary size for seeding in the sea. One problem that this industry faces is that an uneven distribution of juveniles in tanks can lead to variations in the growth rate. Understanding the cues that affect the sheltering behaviours exhibited by juvenile Pacific abalone—namely, the food distribution and the water flow velocity—will help optimize abalone culture settings. In this study, a group of 1,000 juvenile Pacific abalone (distributed across three tanks) was visually observed and enumerated during six experiments that were conducted over a 5‐month study period. It was found that juvenile Pacific abalone preferred to shelter close to food sources when the food was unevenly distributed. When the food was evenly distributed, the juveniles tended to avoid areas of rapid water flow and distributed evenly across the sheltered areas receiving the equal water velocity. This distribution might be the confounding effects between water flow velocity and food stimulus. Based on these findings, it was recommend that the food and water velocity be evenly distributed in an abalone aquaculture system.

The capture efficiency and feeding behaviour of the cold-water coral (CWC) Lophelia pertusa (Linnaeus, 1758) were investigated considering: (1) different food types, (2) different food sizes and (3) different current speeds and temperatures. This study used two different multifactorial experimental approaches: (1) Corals were subjected to three different flow speeds (2, 5 and 10cms−1) in 5l volume tanks, and three different food types (alive zooplankton, alive algae, and dry particulate organic carbon) were offered to the corals under each current regime, analysing the capture rates of the corals under these different flow velocities. (2) In a flume, the feeding behaviour of the coral polyps was studied under different current speed regimes (1, 7, 15 and 27cms−1) and a temperature change over a range of 8–12°C. The obtained results confirm that low flow speeds (below 7cms−1) appear optimal for a successful prey capture, and temperature did not have an effect on polyp expansion behaviour for L. pertusa. In conclusion, flow speeds clearly impact food capture efficiency in L. pertusa, with zooplankton predominantly captured prey at low flow velocities (2cms−1) and phytoplankton captured at higher flow velocities of 5cms−1. This split in capture efficiency may allow corals to exploit different food sources under different tidal and flow conditions.

The growth response of juvenile round gobies was tested in various salinities to assess the potential performance of the species in widely differing salinities in the Baltic Sea and adjacent waters. An experimental approach analysed the survival, daily food intake and growth of juvenile Neogobius melanostomus from the brackish water region of the Kiel Canal, Germany. Round gobies (TL = 61.5 ±5.3 mm; n = 40) were fed ad libitum (diet = mysid shrimp; energy content = 4.7 cal per mg dry weight) at salinity levels of 0.1, 7.5, 15 and 30 over 12 weeks. Two replicate tanks (125 × 30 × 30 cm; 100 L) were maintained for each salinity level, each holding five specimens at a mean temperature of 19.90°C (±0.64°C; n = 136). Survival at all levels was 100%, except for 0.1 with 90%. Mean daily food intake (% of body weight) increased from salinity level 0.1 to 15 (from 17.76% to 19.95%); specimens at level 30 showed a more diversified and lower mean food intake (18.44%). Mean cumulative body weight gain appeared greatest at a level of 7.5 (224.52%), closely followed by 0.1 (206.57%) and 15 (191.92%). In contrast, fish growth was significantly lower at a salinity level of 30 (100.57%). Results of the experiment indicate that salinity tolerance estimates of the round goby made by other authors are too low regarding specimens that stem from brackish habitats. Growth patterns of some specimens, even in the salinity 30 treatment, show that a further spread of this species into regions with higher salinities is quite possible.

Limited food availability and altered thermal regimes (e.g. cold water releases from dams) are two common stressors threatening the persistence of fishes inhabiting anthropogenically disturbed freshwater systems. Yet, the combined effects of these stressors remain poorly characterised. To remedy this, we examined the isolated and combined effects of low temperature exposure and food restriction on specific growth rate (SGR, % body mass/day) and upper thermal tolerance (critical thermal maxima, CTMax) in larval white sturgeon (Acipenser transmontanus [Acipenseridae], 32 days post‐hatch, body mass: 0.25 ± 0.03 g, mean ± standard deviation). A 2 × 2 factorial design was implemented with fish exposed to one of two ecologically‐relevant acclimation temperatures (cold exposure: 11°C or a control temperature: 18°C) and one of two food restriction treatments designed to emulate observed declines in food availability (100% or 40% optimal feed rate) for 6 weeks (N: 3 replicate tanks/treatment, 50 fish/tank). Specific growth rate was affected by both low temperature exposure and food restriction in isolation; low temperature exposure reduced SGR by 56.5% and food restriction reduced SGR by 30.6%. Simultaneous exposure to low temperature and food restriction resulted in a greater but less than additive reduction in SGR (80.6%), indicating that the stressors interacted antagonistically. Critical thermal maxima were c. 2°C higher in 18°C‐acclimated fish (CTMax = 30.7 ± 0.4°C, mean ± standard error) compared to 11°C‐acclimated fish (CTMax = 28.6 ± 0.2°C, mean ± standard error); however, CTMax was independent of food restriction in both 11°C‐ and 18°C‐acclimated fish. These data highlight the unpredictability of stressor interactions and may guide holistic conservation strategies, which target co‐occurring stressors in freshwater habitats.