Design and construction of portable surface aeration pump for tanks and small ponds

The maintenance of adequate dissolved oxygen level is very important in the economy of any aquaculture system. An easy to construct aerating device was created using 0.5 hp water-pump, shower rose, Styrofoam, and rubber hose. The aerator works by drawing water from below and discharging it into the atmosphere as a spray. The spray is aerated as it splashes into the water surface. The aerating device has an average spray of 1.2 unit and doubles the dissolved oxygen content of 37.8 m super(3) tank in one hour

The quest for temperature records in California free of urban heat island effects [abstract, figures, and tables]

EXTRACT (SEE PDF FOR FULL ABSTRACT): The data of this paper differ from the Jones and Bradley papers [of 1982-1986] in that it represents an attempt to select thermal pollution free records rather than to include all available records. The specific long-term trends that this paper is trying to avoid are those illustrated by the heat islands of fast growing urban locations. One other major difference in this paper is that all of the records reported of this study are complete for the entire study period.

Heat-stress and light-stress induce different cellular pathologies in the symbiotic dinoflagellate during coral bleaching

Coral bleaching is a significant contributor to the worldwide degradation of coral reefs and is indicative of the termination of symbiosis between the coral host and its symbiotic algae (dinoflagellate; Symbiodinium sp. complex), usually by expulsion or xenophagy (symbiophagy) of its dinoflagellates. Herein, we provide evidence that during the earliest stages of environmentally induced bleaching, heat stress and light stress generate distinctly different pathomorphological changes in the chloroplasts, while a combined heat- and light-stress exposure induces both pathomorphologies; suggesting that these stressors act on the dinoflagellate by different mechanisms. Within the first 48 hours of a heat stress (32°C) under low-light conditions, heat stress induced decomposition of thylakoid structures before observation of extensive oxidative damage; thus it is the disorganization of the thylakoids that creates the conditions allowing photo-oxidative-stress. Conversely, during the first 48 hours of a light stress (2007 µmoles m−2 s−1 PAR) at 25°C, condensation or fusion of multiple thylakoid lamellae occurred coincidently with levels of oxidative damage products, implying that photo-oxidative stress causes the structural membrane damage within the chloroplasts. Exposure to combined heat- and light-stresses induced both pathomorphologies, confirming that these stressors acted on the dinoflagellate via different mechanisms. Within 72 hours of exposure to heat and/or light stresses, homeostatic processes (e.g., heat-shock protein and anti-oxidant enzyme response) were evident in the remaining intact dinoflagellates, regardless of the initiating stressor. Understanding the sequence of events during bleaching when triggered by different environmental stressors is important for predicting both severity and consequences of coral bleaching

The California heat island: seasonal trends in maximum and minimum temperatures

This paper summarizes progress in an ongoing study of California's temperature trends. It supplements studies reported at PACLIM in 1984, 1986, and 1987. ... Objectives of this study are twofold: to examine and map the trends in maximum and minimum temperatures for the warm and cool seasons separately, and to examine regional differences in maximum and minimum temperature trends in California.

Further studies on dehydration of prawns in rotary drum dryer

The paper deals with studies made to modify the process of drying of prawns in rotary drum dryer reported by the authors earlier. Prawns belonging to any species except M. monoceros can be satisfactorily dried. With M. monoceros invariably considerable adherence of shell occurs. Prawns of any size group can be dried provided in the case of medium and big size prawns they are beheaded prior to drying. In all size groups, beheading prior to drying results in better appearance of the end product in addition to the output of the dryer per charge being increased.

A small scale fish meal dryer

A batch type rotary drum dryer for the production of fish meal suitable for operation in the fishing villages of India has been designed, fabricated and operated successfully. The dyer can be used for production of fish meal from whole lean fish or press-cake from fish body oil extraction plants. The time taken to reach a moisture level below 10% is 5-8 hours depending upon the type of material fed into the dryer.

Heat budget studies of the north Arabian Sea during summer and winter seasons, 1992

In this study heat budget components and momentum flux for August and January 1992 over the north Arabian Sea are computed. The marine meteorological data measured on board during the cruises of PAK-US joint project (NASEER) are used for the computation. Significant differences were found in the heat budget components as well as in the momentum flux during different monsoon periods over the north Arabian Sea. The latent heat flux was always positive and attributed to the large vapour pressure gradient. The computed moisture and latent heat fluxes in January were higher than August The highest value of latent heat flux 309 W/m2 at station 8 was evaluated. These higher latent heat fluxes were due to the large vapour pressure gradient, air-sea temperature difference, the wind speed, and the prevailing wind direction (from north and northeast). Negative values of sensible heat fluxes in both seasons indicate that the heat transfer was from the atmosphere to the ocean. The negative values of net heat gain indicate that the sea surface field became an energy sink: or the sea surface supplied more energy to the atmosphere than it received from it. Large variation in the momentum flux mainly attributed to the variation in the wind speed. Aerial averages of heat and momentum fluxes were also computed.

Comparison of effectiveness of heat and cold shocks applied in the induction of gynogenesis in Clarias gariepinus (Burchell)

An experiment was conducted to optimize the procedure of gynogenesis in African catfish, Clarias gariepinus by suppressing meiotic and mitotic cell divisions in fertilized eggs. Gynogensis was conducted by fertilizing normal eggs with UV-irradiated sperm followed by either heat or cold shocking Irradiation of spermatozoa was given for a duration of 1 min and the eggs were fertilized in vitro. Cold shock at a temperature of 3± 1°C for a duration of 30 and 60 min and heat shock at a temperature of 39± 1°C for a duration of 1 and 2 min was applied to induce diploidy. Higher percentage of hatching (68.66) was observed for meiotic gynogens at a shock temperature of 39± 1°C for a duration of 1 min, 5 min after fertilization (af). Higher percentage of mitotic gynogenetic induction (15.33) was observed at a temperature shock of 39± 1°C for a duration of 1 min, 30 min af.

Quality of fishmeal processed from sun-dried fish in a commercial fishmeal dryer

The physical and chemical compositions of the raw materials received and the composition and nutritive values of the finished products in a commercial size fish meal plant employing the dry rendering process were studied and reported in this paper.

Storage studies on prawns dried in rotary drum dryer

Storage study carried out with prawns processed in rotary drum dryer showed that the deteriorative changes taking place are mostly due to the presence of air and oxygen. By storing under inert atmosphere of nitrogen or carbon dioxide the original characteristics can be maintained over a considerable length of time.

High temperature processing of fish sausage 4. - Heat penetration study

An examination was made of the rate of penetration of heat into fish sausage during processing at 115.6°C. Findings showed processing for 24 minutes to bring about complete destruction of Clostridium botulinum. A processing time of 30 minutes destroys almost all spoilage-causing organisms, thus prolonging the shelf life of the products.

Estimates of the surface heat fluxes in Antarctic waters

The authors have attempted to compute the heat balance terms on the basis of formulas by Budyoko (1974). Some of the meteorological and oceanographic data were collected during the Trans Antarctic Expedition (1989-90). These data were supplemented by the data (1956-1988) made available by the national climatic center of NOAA (National Oceanic and Atmospheric Administration). Monthly means of sea surface temperature in Antarctic waters and meteorological data at a station (77°51'S; 166°39'E) 33m above sea level are given.