Oceanographic Profiling Observations from the MOCE-3 Cruise: 27 October to 15 November 1994

This report contains results from the third cruise of the Marine Optical Characterization Experiment (Fig. 1). A variety of spectroradiometric observations of the upper water column and atmosphere were made by investigators from the University of Miami, NOAA, CHORS and MLML. Data presented here were obtained by oceanographic CTD profiler: salinity, temperatllre, dissolved oxygen, beam attenuation and chlorophyll-a fluorescence; and by water samplers: total suspended matter and suspended organic carbon and nitrogen, salinity, and dissolved oxygen.

Effects of some environmental factors on the fecundity of Tilapia species (Family Cichlidae) in Kigera Reservoir, New Bussa

The effects of some environmental factors on the fecundity of Tilapia species (Family Cichilidae) was carried out at the Kigera dam. Four Tilapia species caught were Tilapia zilli, Hemichromis fasciatus, Sarotherodon galilaeus and Oreochromis niloticus while the environmental factors considered were water temperature, Dissolved Oxygen, pH value, level of rainfall and rate of sunshine and range of time. 43 fish comprising of 25 male with (58.1%) and 18 females having (41.9%) were studied with 74.42% been sexually matured. Both high levels of rainfall and dissolved oxygen favoured fecundity. The spawning peak occurred in (July), environmental factors monitored indicated that dissolved oxygen ranges from 3.7 to 4.45mg/lit rainfall ranges from (34.90mm to 237.80mm) sunshine ranges from (5hrs-8hrs) and pH ranges from (7.35-7.45). The spawning of these species in their natural or hatchery condition is therefore best achieved during the peak of raining season

The relationship between some physicochemical parameters and plankton composition on fish production in ponds

The effect of physico-chemical parameters and plankton composition on fish production in ponds was investigated in six fish farms for eight weeks. The physicochemical parameters investigated were temperature=25-30 plus or minus C, transparency=0.45-0.57m, dissolved oxygen=3.0-10.9mg/l, pH=6.0-7.7, dissolved carbon dioxide=5.46-28.3mg/l, total alkalinity=44.37-80.0ppm, chemical oxygen demand=31.88-72.18mg/l and biological oxygen demand=0.66-48.34mg/l. Plankton composition varies and was made of four families of phytoplankton namely: Cyanophyceae, Chlorophyceae, Dinophyceae and Diatomida; and four families of zooplankton viz: Protozoa, Rotifera, Copepoda and Dinoflagellates. Farm 1 and 6 recorded the highest average weight of about 1.0kg and average total length of about 40.0cm for the two fish species. This study showed that fish yield was dependable on the quality and management of pond water characteristics

Development and collapse of an Oscillatoria bloom in Loch Leven during July 1994

During 1994, weekly spot-sampling of open water sites on Loch Leven took place from 16th March onwards. Very little difference between spot-sampling sites was observed from 16th March to 5th July. Throughout April and May there was a slow increase in levels of chlorophyll-a, followed by a rapid increase through June, reaching a maximum of 230 micrograms per litre. On 8th July there was a very rapid rise in water temperature, with a corresponding increase in dissolved oxygen and pH. At 0915 hours on 9th July there was a drop in all three variables. These changes were coincident with a marked reduction in chlorophyll-a values falling to 70 micrograms per litre on 12th July. On 16th July evidence of a resurgence of photosynthesis was observed.

Comparison of permanent and temporary streams of calcareous Provence [Translation from: Annales de Limnologie 9(3) 273-292, 1973]

The rainfall regime and the karstic nature of the subsoil determines the alternation of a period of flow and a period of drought for a large number of Mediterranean streams. Amongst this type of stream it is possible to distinguish temporary streams, characterised by a period of flow for several months permitting the establishment of the principal groups of aquatic insects; and ephemeral streams whose very brief period of flow permits the establishment of a community reduced to a few species of Diptera. This paper aims to study the structure of the communities which colonise this particular type of stream and the ecology of the principal species which constitute these communities. Four French temporary streams were examined and temperature regimes, dissolved oxygen, calcium and magnesium measured. Samples of fauna were taken regularly and the biotic composition established. The analysis of similarities between the three permanent streams are discussed and compared with permanent streams.

Eléments nutritifs et production primaire dans les lagunes du Côte d'Ivoire : cycle annuel

This paper collects most of the information gathered between October 1974 and July 1976 within the framework of a research program concerning the hydrobioclimate of ivorian lagoons and especially the Ebrié lagoon. Monthly surveys concerning the latter were carried out during 1975. The following parameters - and their vertical distribution wherever it had a meaning - were systematically gathered in a system of fifty-five stations: Transparency (Secchi), Temperature, Salinity, Chlorophylla, Dissolved oxygen, phosphate, nitrate, nitrite. These data provide an outline of the annual cycle of nutrients and primary production of the Ivoirian lagoons

Polyculture du machoiron Chrysichthys nigrodigitatus avec Oreochromis niloticus en etang

Fingerling catfish Chrysichthys nigrodigitatus (P=4.0 g, FL=65.3 mm) and Oreochromis niloticus (P=11.2 g, TL=84.8 mm) were stocked in 0.06 ha earthen ponds at Pass (Annex of the Aquaculture Research Station at Layo, Côte d'Ivoire). The ponds were stocked at densities of 6700 catfish per ha, and 6700 catfish with 3350 tilapias per ha. The study lasted from February to August 1985 and the fish were fed daily at 6% of the estimated catfish biomass with 32% protein pellet. There were no differences in mean weekly water temperature (p > 0.05). The dissolved oxygen concentration was higher in ponds where tilapias were added (p < 0.05) The presence of tilapias seems to have improved water quality and did not affect growth and production of catfish (p > 0.05). Their presence also significantly increased total fish yield (p < 0.05) by 23.5%. There were no significant differences (p > 0.05) in catfish survival between the two production systems.

L'oxygene au large de Grand Bassam (Cote d'Ivoire)

The present paper deals with the variations of the dissolved oxygen content off Grand Bassam (11 miles east of Abidjan, Côte d'Ivoire), during nearly five years (March 1966 to September 1970). Although we find in general the low oxygen values near the bottom, the dissolved oxygen content is at its absolute minimum during the upwelling. There is a good correlation between the Secchi depth and the depth of the well ventilated layer. About 10% of surface irradiance is found at the layer where the dissolved oxygen content equals 80% of the oxygen content found at surface.

Tracking migratory salmonids

The River Ribble drains into the Irish sea on the West coast of England. The estuary is approximately 20Km long, tunnel shaped, tapering from a 100m width at Preston dock to 5 km at Lytham where it enters the sea. This is a preliminary report on a study of oxygen requirements of Atlantic salmon (Salmo salar)and sea trout (Salmo trutta) in an estuary. Oxygen sending transmitters attached to fish were used to determine exposure of individuals to different dissolved oxygen concentrations as they moved in from the sea through the estuary of the River Ribble. This estuary is subject to extreme variations in dissolved oxygen concentrations. This report is based on the latest transcription and analysis of data completed in October 1983. The aim of this report is to give an overview of the work done and conclusions which are apparent at this stage.

A preliminary assessment of water quality in fish cages on Lake Kariba, Zimbabwe

The water quality in fish cages on Lake Kariba was studied. The Kruskal-Wallis test was used to determine whether the water quality parameters differed significantly among the cage-types (cage-type effect). Secchi disc readings ranged from 2 to 4 metres, while temperature ranged from 23 degree C to 29.5 degree C. The observed conductivity was between 98.7 mu S/cm and 102.3 mu S/cm. The pH was between 6.31 and 7.82. Concentrations of dissolved oxygen varied from 1.55 to 6.47 mg/l, while dissolved oxygen saturation ranged from 22.3% to 83.1%. Within the same month, temperature did not differ significantly among cages. Conductivity, pH, dissolved oxygen concentration and dissolved oxygen saturation differed significantly among the 3 cage-types. Temperature and pH levels in the cages were close to the optimum levels for the culture of cichlids. Sub-optimal levels of dissolved oxygen occurred occasionally in the octagonal cages.

Ichthyoplankton community structure and comparative trophodynamics in an estuarine transition zone

Surveys were conducted to evaluate and compare assemblage structure and trophodynamics of ichthyoplankton, and their variability, in an estuarine transition zone. Environmental gradients in the saltfront region of the Patuxent River subestuary, Chesapeake Bay, were hypothesized to define spatiotemporal distributions and assemblages of ichthyoplankton. Larval fishes, zooplankton, and hydrographic data were collected during spring through early summer 2000 and 2001. Larvae of 28 fish species were collected and species richness was similar each year. Total larval abundance was highest in the oligohaline region down-estuary of the salt front in 2000, but highest at the salt front in 2001. Larvae of anadromous fishes were most abundant at or up-estuary of the salt front in both years. Two ichthyoplankton assemblages were distinguished: 1) riverine—characterized predominantly by anadromous species (Moronidae and Alosinae); and 2) estuarine—characterized predominantly by naked goby (Gobiosoma bosc) (Gobiidae). Temperature, dissolved oxygen, salinity-associated variables (e.g., salt-front location), and concentrations of larval prey, specifically the calanoid copepod Eurytemora affinis and the cladoceran Bosmina longirostris, were important indicators of larval fish abundance. In the tidal freshwater region up-estuary of the salt front, there was substantial diet overlap between congeneric striped bass (Morone saxatilis) and white perch (M. americana) larvae, and also larvae of alewife (Alosa pseudoharengus) (overlap= 0.71–0.93). Larval abundance, taxonomic diversity, and dietary overlap were highest within and up-estuary of the salt front, which serves to both structure the ichthyoplankton community and control trophic relationships in the estuarine transition zone.

Environmental characterization of seasonal trends and foraging habitat of bottlenose dolphins (Tursiops truncatus) in northern Gulf of Mexico bays

A description of the foraging habitat of a cetacean species is critical for conservation and effective management. We used a fine-scale microhabitat approach to examine patterns in bottlenose dolphin (Tursiops truncatus) foraging distribution in relation to dissolved oxygen, turbidity, salinity, water depth, water temperature, and distance from shore measurements in a highly turbid estuary on the northern Gulf of Mexico. In general, environmental variation in the Barataria Basin marine environment comprises three primary axes of variability (i.e., factors: temperature and dissolved oxygen, salinity and turbidity, and distance and depth) that represent seasonal, spatial-seasonal, and spatial scales, respectively. Foraging sites were differentiated from nonforaging sites by significant differences among group size, temperature, turbidity, and season. Habitat selection analysis on individual variables indicated that foraging was more frequently observed in waters 4–6 m deep, 200–500 m from shore, and at salinity values of around 20 psu. This fine-scale and multivariate approach represents a useful method of exploring the complexity, gradation, and detail of the relationships between environmental variables and the foraging distribution patterns of bottlenose dolphin.

Pig dung as pond manure: effect on water quality, pond productivity and growth of carps in polyculture system

Pig dung was used as manure at 18 and 36 t/ha/year in carp polyculture (without supplementary feeding) for 270 days. It was observed that pig dung at both the levels did not degrade the physico-chemical properties (pH, dissolved oxygen and alkalinity) of water. The nutrient (phosphates and nitrates) level of water was higher in manured ponds than control ponds (no manuring, only supplementary feeding). Further, plankton levels (phyto- and zooplankton) were also significantly higher in manured ponds. The growth of Catla catla and Labeo rohita was significantly more in manured ponds than in control ponds. Growth of Cirrhinus cirrhosus and Cyprinus carpio was significantly more in ponds manured with pig dung at 18 t/ha/year than in control ponds and the growth of Ctenopharyngodon idellus was significantly more in control than in manured ponds.

Physico-chemical factors and bacteria in fish ponds

Analyses of pond water and mud samples show that nitrifying bacteria (including ammonifying bacteria, nitrite bacteria, nitrobacteria and denitrifying bacteria) are in general closely correlated with various physico-chemical factors, ammonifying bacteria are mainly correlated with dissolved oxygen; denitrifying bacteria are inversely correlated with phosphorus; nitrite bacteria are closely correlated with nitrites, nitrobacteria are inversely correlated with ammoniac nitrogen. The nitrifying bacteria are more closely correlated with heterotrophic bacteria. Nitrobacteria are inversely correlated with anaerobic heterotrophic bacteria. The correlation is quite weak between all the nitrite bacteria which indicates that the nitrite bacteria have a controlling and regulating function in water quality and there is no interdependence as each plays a role of its own. The paper also discusses how the superficial soil (pond mud down to 3.5 cm deep) and different layers of the mud affect the biomass of bacteria. The study shows that the top superficial layer (down to 1.5 cm deep) is the major area for decomposing and converting organic matter.

Stillwaters monitoring programme.Summary results 2003 and 2004

This is the Stillwaters monitoring programme. Summary results 2003 and 2004 from the Environment Agency North West. This report is focuses in The Winter Monitoring of Stillwaters Programme, which began in January 2001 with the aim of gathering long term data on nutrient abundance over winter months. This allows assessment of nutrient ‘carry-over’ available for algal growth in the following year, plus year-on-year productivity. 14 stillwaters are monitored each year. The environmental issues associated with each Stillwater are summarised in the table below. Bank-side water samples are taken for nutrients (N, P and S) and chlorophyll. A YSI multi-parameter sonde measures temperature, pH, specific conductivity and dissolved oxygen (% saturation). Survey results shown in this report came from: Oak Mere and Bar mere.