Fish distribution in a small domestic water supply reservoir: a case study of Kangimi Reservoir, Kaduna, Nigeria

A study of the composition and distribution of fish populations in the inshore, surface and bottom water habitats of Kangimi Reservoir showed that the most abundant family was the Cichlidae followed in order of abundance by the familiesCyprinidae, Schilbeidae, Mormyridae, Mochokidae, Characidae, centropomidae and Bagridae. Though the overall composition of families caught inn the three habitats did not vary significantly (P>0.05) only family Cichlidae showed habitat preference: there was a preponderance of Cichlidae in the inshore water habitat (P<0.05). The families Bagridae and Centropomidae were caught only in the inshore and bottom water habitats while the other families were caught from all habitats and showed no habitat preference. The dominance of primary and secondary consumers indicates high fish production potential under adequate management

Energy Supply and the Sustainability of Endogenous Growth

29 p.

Households WTP for the Reliability of Gas Supply

26 p.

Devil's Gate Reservoir and its effect upon Pasadena's water supply

[Intro.] The Devil’s Gate Dam has been of great benefit to Pasadena’s water supply, in that it prevents a large amount of the flood waters of the Arroyo Seco being wasted into the ocean.

Freshwater biology and water supply in Britain

This paper is designed to give a general account of freshwater biology as it bears on waterworks practice. Most water that is used for consumption will commonly go through a storage reservoir. Here special reference is given to the biological relations in standing waters, the biological control of water supplies, methods of plankton estimation, the biology of slow sand filtration and the use of algicides.

Detecção e classificação de VTCDs em sistemas de distribuição de energia elétrica usando redes neurais artificiais.

O objetivo deste trabalho é conhecer e compreender melhor os imprevistos no fornecimento de energia elétrica, quando ocorrem as variações de tensão de curta duração (VTCD). O banco de dados necessário para os diagnósticos das faltas foi obtido através de simulações de um modelo de alimentador radial através do software PSCAD/EMTDC. Este trabalho utiliza um Phase-Locked Loop (PLL) com o intuito de detectar VTCDs e realizar a estimativa automática da frequência, do ângulo de fase e da amplitude das tensões e correntes da rede elétrica. Nesta pesquisa, desenvolveram-se duas redes neurais artificiais: uma para identificar e outra para localizar as VTCDs ocorridas no sistema de distribuição de energia elétrica. A técnica aqui proposta aplica-se a alimentadores trifásicos com cargas desequilibradas, que podem possuir ramais laterais trifásicos, bifásicos e monofásicos. No desenvolvimento da mesma, considera-se que há disponibilidade de medições de tensões e correntes no nó inicial do alimentador e também em alguns pontos esparsos ao longo do alimentador de distribuição. Os desempenhos das arquiteturas das redes neurais foram satisfatórios e demonstram a viabilidade das RNAs na obtenção das generalizações que habilitam o sistema para realizar a classificação de curtos-circuitos.

Variability in supply and cross-shelf transport of pink shrimp (Farfantepenaeus duorarum) postlarvae into western Florida Bay

The variability in the supply of pink shrimp (Farfantepenaeus duorarum) postlarvae and the transport mechanisms of planktonic stages were investigated with field data and simulations of transport. Postlarvae entering the nursery grounds of Florida Bay were collected for three consecutive years at channels that connect the Bay with the Gulf of Mexico, and in channels of the Middle Florida Keys that connect the southeastern margin of the Bay with the Atlantic Ocean. The influx of postlarvae in the Middle Florida Keys was low in magnitude and varied seasonally and among years. In contrast, the greater postlarval influx occurred at the northwestern border of the Bay, where there was a strong seasonal pattern with peaks in influx from July through September each year. Planktonic stages need to travel up to 150 km eastward between spawning grounds (northeast of Dry Tortugas) and nursery grounds (western Florida Bay) in about 30 days, the estimated time of planktonic development for this species. A Lagrangian trajectory model was developed to estimate the drift of planktonic stages across the SW Florida shelf. The model simulated the maximal distance traveled by planktonic stages under various assumptions of behavior. Simulation results indicated that larvae traveling with the instantaneous current and exhibiting a diel behavior travel up to 65 km and 75% of the larvae travel only 30 km. However, the eastward distance traveled increased substantially when a larval response to tides was added to the behavioral variable (distance increased to 200 km and 85% of larvae traveled 150 km). The question is, when during larval development, and where on the shallow SW Florida shelf, does the tidal response become incorporated into the behavior of pink shrimp.

Reducing feed costs in semi-intensive finfish culture: an update on mixed feeding schedules and an idea for enhancing endogenous food supply in ponds

Some interesting ideas on improving the cost-effectiveness of feeding in semi-intensive finfish aquaculture are presented.