Geochemical evidence for enhanced upwelling and organic productivity during the late Quaternary on the continental margin of northern California

EXTRACT (SEE PDF FOR FULL ABSTRACT): Laminated sediments are preserved in upper Pleistocene sections of cores collected on the continental slope at water depths within the present oxygen-minimum zone from at least as far north as the Klamath River and as far south as Point Sur. Comparison of sediment components in the laminae with those delivered to sediment traps as pelagic marine "snow" show the dark/light lamination couplets are indeed annual (varves). ... The presence of carbon-, sulfur-, and metal-rich sediments, as well as lack of bioturbation, all support the theory that the oxygen-minimum zone in the northeastern Pacific Ocean was more intense - in fact, anoxic - during the late Pleistocene in response to greater coastal upwelling and higher organic productivity.

Physical variables, nutrient status and primary productivity of Kyoga Basin lakes of Lemwa, Omunuo, Gawa, Adois and Owapet

The review report on Kyoga basin lakes (NAFIRRI 2007) described Kyoga basin lakes as important natural resource for the communities within the basin and the surrounding areas. Fisheries of the basin provide a source of protein, income, and employment to generally poor communities in the area. The lakes also generate revenue to the local Governments within the catchment. This indicates that the fisheries of Kyoga basin lakes are a key instrument in poverty eradication and food security. The lakes also act as a source of water for domestic, agricultural and transport purposes. Some of the Kyoga small lakes harbour fish species, which have disappeared from the main lakes Victoria and Kyoga and are therefore important for biodiversity conservation

Seasonality, labor and integration of aquaculture into southern African smallhold farming systems

Fish production on Malawian smallholdings is generally limited by the quantity and quality of inputs to the pond (Brummett and Noble 1995). The timing of labor availability and other farm activities limit the amount farmers put into their ponds resulting in lower growth rates and yields. There is potential for improving production and yields through modifications of production schedules to accommodate other farming activities. Limited material and labor inputs among farming system enterprises can be better allocated by considering seasonal availability of inputs and adapting the pond and fish farming technology to the farming system. This case from Malawi demonstrates that aquaculture technology that neglects the annual cycle of events and constraints on the farm will not be easily integrated into the farming system. Focusing on technology that maximizes fish production rather than facilitation of adoption and integration has been a feature of the majority of African smallholder agriculture/aquaculture projects. Farming Systems Research (FSR) must identify niches and opportunities for system improvement for it to be worth supporting as a development intervention.

Nutrient profile of pond water in north-eastern state of Tripura and impact of water acidity on aquaculture productivity

Physicochemical parameters of 31 fish pond water samples of Tripura were studied to ascertain the nutrient profile of acidic soil zone and the impact of water acidity towards aquaculture productivity. The pH was acidic (mean 6.63±0.44) with high Fe (mean1.04±0.40 mglˉ¹) and AI (mean 2.67±2.41 mglˉ¹) contents. These were mostly responsible for pond water acidity and poor productivity with low nitrogen, phosphate and total alkalinity. The study also showed strong negative relationship between water pH and redox potential (R²=0.5251). However, pH was positively significant with electrical conductivity. The roles of redox potential and electrical conductivity in water acidity were found highly important. Available calcium content was also found low (mean 2.91±2.96 mglˉ¹). Elevating level of pH of pond water could be the possible management practices in acidic water so that such unproductive water might be productive enough with higher phosphate and nitrogen levels for better biological production.

Some relationships of meteorological, hydrographic, and biological variables in the Gulf of Panama

ENGLISH: An average of 78 m. of water was vertically displaced by wind-driven upwelling during the dry season (January-April) in Panama Bay at the head of the Gulf of Panama. The standing crop of phytoplankton and its productivity were significantly greater during the months of upwelling than during the rainy season. Equivalent results were found by three different methods used to calculate photosynthesis: direct measurement with radiocarbon; increase of dissolved oxygen in the water column; and decrease of phosphate-phosphorus in the water column. About 90 g. of carbon per square meter of sea surface were fixed by the phytoplankton during each upwelling season (January-April) and about 90 g. of carbon were fixed during each rainy season (May-December) resulting in an annual production of about 180 g. of carbon per square meter of sea surface SPANISH: Un promedio de 78 m. de agua fué desplazado verticalmente por la fuerza de los vientos que ocasionan el fenómeno conocido por afloramiento durante la estación seca (enero a abril) en la Bahía de Panamá, a la cabeza del Golfo de Panamá. La cosecha estable de fitoplancton y su productividad fueron significativamente mayores durante los meses de afloramiento, que durante la estación lluviosa. Se obtuvieron resultados equivalentes por medio de tres diferentes métodos usados para calcular la fotosíntesis: medición directa con radiocarbono, aumento del oxígeno disuelto en la columna de agua, y disminución del fosfato-fósforo en la columna de agua. Por medio del fitoplancton durante cada estación de afloramiento (enero-abril), se fijaron alrededor de 90 g. de carbono por metro cuadrado de la superficie del mar, y durante cada estación lluviosa (mayo-diciembre) se fijaron 90 g. de carbono lo que resulta en una producción anual de aproximadamente 180 g. de carbono por metro cuadrado de la superficie del mar.

The incidence of Nypa fruticans (Wurmb) and its impact on fisheries production in the Niger Delta mangrove ecosystem

Nypa fruticans occurs in Bayelsa, Rivers, Akwa Ibom and Cross River State, Nigeria; invading an estimated area of 821 Km super(2) mangrove dominated swamps. Human activities such as tree felling, urbanization, oil and gas exploration and exploitation and other activities led to the interference in the normal mangrove by the Nypa palm. Lack of utilization by the local population of the Nypa palm as in into-pacification has increased the population over the years. The effect includes the reduction in primary and secondary productivity, disruption of food chain and erosion of riverbanks. The eradication of the Nypa palm from the Niger delta mangrove ecosystem and replacement with red and white mangroves will restore the ecosystem health and enhance biological diversity

Nitrates in surface waters, inputs and seasonality: Phase 2

Changes in management practices and agricultural productivity over the past twenty years have lead to nitrate pollution and eutrophication of lakes and rivers. Information on nitrate concentrations and discharge has been collected on the River Frome at East Stoke since 1965, using the same analytical nitrate method so that the results are comparable. These records of weekly spot values of nitrate concentration and daily mean discharges have been analysed for trends and seasonal patterns in both concentration and nitrate loadings. In this extension of our nitrate contract, a new automated method of intensive sampling has been used to monitor short-term variability and to assess how well similar routine (weekly) sampling schemes can represent the true nitrate record.

The Federal Fisheries Service, 1871–1940: Its Origins, Organization, and Accomplishments

The U.S. Fish Commission was initiated in 1871 with Spencer Fullerton Baird as the first U.S. Fish Commissioner as an independent entity. In 1903 it became a part of the new U.S. Department of Commerce and Labor and was renamed the Bureau of Fisheries, a name it retained when the Departments of Commerce and Labor were separated in 1912. The Bureau remained in the Commerce Department until 1941 when it was merged with the Biological Survey and placed in the Department of Interior as the U.S. Fish and Wildlife Service. It was a scientific agency with well conceived programs of action, and it provided knowledge, advice, and example to state governments and individuals with fisheries interests and needs. Its efforts were supported by timely international agreements which constituted the precedent for Federal interest in fishery matters. The Fisheries Service earned stature as an advisor through heavy emphasis on basic biological research. The lack of such knowledge was marked and universal in the 1870’s, but toward the end of that decade, strong steps had been taken to address those needs under Baird’s leadership. USFC research activities were conducted cooperatively with other prominent scientists in the United States and abroad. Biological stations were established, and the world’s first and most productive deepsea research vessel, the Albatross, was constructed, and its 40-year career gave a strong stimulus to the science of oceanography. Together, the agency’s scientists and facilities made important additions to the sum of human knowledge, derived principles of conservation which were the vital bases for effective regulatory legislation, conducted extensive fish cultural work, collected and disseminated fisheries statistics, and began important research in methods of fish harvesting, preservation, transportation, and marketing.

Linking climate change, rice yield, and migration: the Philippine experience

This study tests the hypothesis that climate change, through its rice productivity impacts, induces out-migration in the Philippines. Results show that climate change effects such as increasing night time temperature and extreme rainfall pattern, by way of reduction in rice yield and farm revenues, significantly increases the number of Overseas Filipino Workers. Findings also show that overseas migration of female workers is more sensitive to climate and rice productivity changes compared to male overseas migration. However, unlike overseas migration, the reduction in yield and farm revenues act as a constraint to domestic migration.