In vitro effects of fungicides on the fungus Haliphthoros philippinensis

Pure cultures of Haliphthoros philippinensis, isolated from infected Penaeus monodon larvae, were exposed for 24 hours to varying concentrations of antifungal agents. The efficiency of each agent to inhibit sporulation and mycelial growth was measured. Effects on P. monodon eggs and larvae were also investigated. It is concluded that preliminary bioassay of larval tolerance to the suggested effective doses should always be made prior to prophylaxix or therapeutic applications.

Culturing the African lungfish in Uganda: effects of exogenous fish feed on growth performance in tanks

The availability of African lungfish (Protopterus aethiopicus) in many communities in Uganda is declining. Indigenous efforts to culture this fish usually produce poor yields and depend on feeding fish fry, minced meat, and leftover food. This study evaluates three formulated diets (diet-1, diet-2, diet-3) fed to wild caught lungfish fingerlings reared in indoor tanks for 77 days. Experimental fish gradually accepted sinking pellets, and marginal increases in average body weight were observed. Mean (± SE) final weight (15.86 ± 0.80 g) for fish fed on diet-3 was significantly higher (p < 0.05) than fish fed diet-1 and diet-2. Specific growth rates (SGR) for diet- 3 were significantly higher (p < 0.05) than diet-1, and marginally more than diet-2 (0.37 ± 0.04 %/ d). Feed conversions were similar (p >0.05), ranging from 1.61 ± 0.26 to 2.07 ± 0.11. Survivals after an 11-week culture were relatively low (< 60%), but generally increased (R2 = 0.667, P = 0.007) with increasing dietary proteins. Diet-3 had a significant higher survival rate (p< 0.05) than diet-1 and diet-2. Significant growth performance was attained with diet-3. This study demonstrated that sinking fish feed pellets can be used to culture wild-caught African fingerlings in captivity.

The nature of small-scale farmer managed irrigation systems in North West Province, Sri Lanka and potential for aquaculture

RRAs were carried out in two Small Tank Cascade systems (STCs) of North West Province, Sri Lanka (less than 1000 ha total watershed area). A total of 21 tanks and 7 villages were investigated with primary emphasis on two upper watershed communities. The two systems differ primarily in their resource base; namely rainfall, natural forests and proximity to large scale perennial irrigation resources. [PDF contains 86 pages]

Culture of green algae Chlorella ellipsoidea in inexpensive media

The culture of the of green alga Chlorella ellipsoidea was conducted under natural conditions at the same place simultaneously in five different media, viz., medium-I (inorganic medium), medium-II (powdered whole-pulse medium), medium-III (medium of pulse bran), medium-IV (mixed medium = 50% inorganic medium + 50% whole-pulse powder medium), medium-V (mixed medium = 50% inorganic medium + 50% pulse bran medium). The culture was done in 500 ml conical flask. Growth rates of C. ellipsoidea in five different media were different and reached maximum cell densities of 0.63 x 10^6 cells per ml in 8 days in medium-I, 4.02 x 10^6 cells per ml in 10 days in medium-II, 3.62 x 10^6 cells per ml in 9 days in medium-III, 4.38 x 10^6 cells per ml in 11 days in medium-IV and 4.36 x 10^6 cells per ml in 11 days in medium-V. The range of air temperature was 20 to 33°C and that of culture media was 24 to 32°C and light intensity was 2000 to 7000 lux during the culture period. The inexpensive culture media were found to be significantly useful for algal culture.

Proximate composition and mineral contents of pebbly fish, Alestes baremoze (Joannis, 1835) fillets in relation to fish size

Alestes baremoze (Joannis, 1835), locally known as Angara in Uganda, is native to fresh water systems in Africa, thriving well in both lacustrine and riverine conditions. It is part of the routine diets of families in northern Uganda, South Sudan, the Sudan and the Democratic Republic of Congo. The objective of this study was to determine the proximate composition and mineral contents of A. baremoze fillets according to fish size. The mineral contents of A. baremoze from Lake Albert were analysed using standard procedures. The fish samples were categorised into three size-groups; <1 kg (880–990g), 1-1.5 kg and 1.6-2.5 kg. On wet weight basis, there were no significant differences (p>0.05) in crude protein and ash content among the different fish sizes. However, there were significant differences (p<0.05) in crude fat, carbohydrate, gross energy and vitamin A. Crude fat (0.35%), carbohydrate (0.37%) and gross energy (597.6 Kcal/100 g) were significantly higher in medium sized fish (1 to 1.5 kg) compared with the larger fish category. Vitamin A contents of different fish sizes ranged from 55.1 to75.3 μg RAE/100g. The contents of magnesium and iron were highest in sizes <1 kg (5.34 mg/100 g) and (3.58 mg/100 g), respectively. It was observed that potassium content (339.33 mg/100 g) and calcium (29.75 mg/100 g) were significantly higher (p<0.05) in fish >1.5 kg. These findings suggest that taste, freshness and other related external appearances should not be the only factors to be considered in making choice for marketing and consumption of Alestes baremoze.

Benthic Macrofauna of the New York Bight, 1979-89

The benthic macrofauna of the New York Bight has been monitored extensively, primarily to determine trends over space and time in biological effects of waste inputs. In the present study, from 44 to 48 stations were sampled each summer from 1980-1985. Data from other Bight benthic studies are included to· extend the temporal coverage from 1979 to 1989. Numbers of species and amphipods per sample, taken as relatively sensitive indicators of environmental stress, showed consistent spatial patterns. Lowest values were found in the Christiaensen Basin and other inshore areas, and numbers increased toward the outermost shelf and Hudson Shelf Valley stations. There were statistically significant decreases in species and amphipods at most stations from 1980 to 1985. (Preliminary data from a more recent study suggest numbers of species increased again between 1986 and 1989.) Cluster analysis of 1980-85 data indicated several distinct assemblages-sewage sludge dumpsite, sludge accumulation area, inner Shelf Valley, outer Shelf Valley, outer shelf-with little change over time. The "enriched" and "highly altered" assemblages in the Basin appear similar to those reported since sampling began there in 1968. No consistently defaunated areas have been found in any sampling programs over the past 20 years. On a gross level, therefore, recent faunal responses to any environmental changes are not evident, but the more sensitive measures used, i.e. numbers of species and amphipods, do indicate widespread recent effects. Causes of the faunal changes are not obvious; some possibilities, including increasing effects of sewage sludge or other waste inputs, natural factors, and sampling artifacts, are discussed. (PDF file contains 54 pages.)

The effect of autotrawl systems on the performance of a survey trawl

Three aspects of a survey bottom trawl performance—1) trawl geometry (i.e., net spread, door spread, and headrope height); 2) footrope distance off-bottom; and 3) bridle distance off-bottom—were compared among hauls by using either of two autotrawl systems (equal tension and net symmetry) and hauls conducted with towing cables of equal length and locked winches. The effects of environmental conditions, vessel heave, crabbing (i.e., the difference between vessel heading and actual vessel course over ground), and bottom current on trawl performance with three trawling modes were investigated. Means and standard deviations of trawl geometry measures were not significantly different between autotrawl and locked-winch systems. Bottom trawls performed better with either autotrawl system as compared to trawling with locked winches by reducing the variance and increasing the symmetry of the footrope contact with the bottom. The equal tension autotrawl system was most effective in counteracting effects of environmental conditions on footrope bottom contact. Footrope bottom contact was most inf luenced by environmental conditions during tows with locked winches. Both of the autotrawl systems also reduced the variance and increased the symmetry of bridle bottom contact. Autotrawl systems proved to be effective in decreasing the effects of environmental factors on some aspects of trawl performance and, as a result, have the potential to reduce among-haul variance in catchability of survey trawls. Therefore, by incorporating an autotrawl system into standard survey procedures, precision of survey estimates of relative abundance

ENSO and precipitation variability over Mexico during the last 90 years

Latin America has been shown to be susceptible to climatic anomalies during El Niño/Southern Oscillation (ENSO) events (eg, Aceituno 1988; Ropelewshi and Halpert 1987; Kiladis and Diaz 1989). While these studies have emphasized ENSO-related rainfall and temperature anomalies over Central and South America, less work has been done on the climatic effects of ENSO over the Mexican region. In this study we are investigating interannual and intraseasonal fluctuation in temperature and precipitation over the southwestern United States and Mexico since the turn of the century. We are particularly interested in the effects of ENSO on the interannual variability over this region. This report focuses on the association between ENSO and interannual variability of precipitation over Mexico.

Opportunistic feeding of longhorn sculpin (Myoxocephalus octodecemspinosus): Are scallop fishery discards an important food subsidy for scavengers on Georges Bank?

There has been much recent interest in the effects of fishing on habitat and non-target species, as well as in protecting certain areas of the seabed from these effects (e.g. Jennings and Kaiser, 1998; Benaka, 1999; Langton and Auster, 1999; Kaiser and de Groot, 2000). As part of an effort to determine the effectiveness of marine closed areas in promoting recovery of commercial species (e.g. haddock, Melanogrammus aegelfinus; sea scallops, Placopecten magellanicus; yellowtail flounder, Limanda ferruginea; cod, Gadus morhua), nontarget species, and habitat, a multidisciplinary research cruise was conducted by the Northeast Fisheries Science Center (NEFSC), National Marine Fisheries Service. The cruise was conducted in closed area II (CA-II) of the eastern portion of Georges Bank during 19–29 June 2000 (Fig. 1). The area has historically produced high landings of scallops but was closed in 1994 principally for groundfish recovery (Fogarty and Murawski, 1998). The southern portion of the area was reopened to scallop fishing from 15 June to 12 November 1999, and again from 15 June to 15 August 2000. While conducting our planned sampling, we observed scallop viscera (the noncalcareous remains from scallops that have been shucked by commercial fishermen at sea) in the stomachs of several fish species at some of these locations, namely little skate (Raja erinacea), winter skate (R. ocellata), red hake (Urophycis chuss), and longhorn sculpin (Myoxocephalus octodecemspinosus). We examined the stomach contents of a known scavenger, the longhorn sculpin, to evaluate and document the extent of this phenomenon.

Influence of some abiotic factors on the acute toxicity of cadmium to Cyprinus carpio

Hardness of water had significant effect on the acute toxicity of cadmium to common carp, Cyprinus carpio. The 96h LC sub(50) and safe application rate increased from 43.17 and 22.77 mg 1 super(-1) in soft water (0.9 mM Ca super(2+) l super(-1)) to 310.48 and 177.66 mg l super(-1), respectively, in very hard water (6.0 mM Ca super(2+) l super(-1)). In medium hard and hard water, 96h LC sub(50) values were 48.39 and 116.45 mg l super(-1). When sediments were included in the medium hard, hard and very hard water treatments, the 96h LC sub(50) were 111.20, 133.71 and 334.47 mg l super(-1), respectively. Among these values, the one for medium hard water with sediment treatment was significantly higher than medium hard water treatment; values for the other two treatments were non-significant when compared with respective water treatments. Sediment was able to reduce the acute toxicity of cadmium mainly due to the complexation of cadmium with dissolved organic carbon (DOC). At the lower hardness level, cadmium complexed with DOC and the acute toxicity was reduced significantly. At higher hardness, most of the DOC sites were occupied by calcium and the acute toxicity of cadmium was not significantly reduced in hard water with sediment and very hard water with sediment experiments in comparison to respective water treatments.