Trophic impact, metabolism, and biogeochemical role of the marine cladoceran Penilia avirostris and the co-dominant copepod Oithona nana in NW Mediterranean coastal waters

In this work we studied the trophic ecology and feeding impact of the cladoceran Penilia avirostris and the cyclopoid copepod Oithona nana, the two dominant zooplankters in the summer communities of the coastal NW Mediterranean, on the naturally occurring microbial communities. In order to ascertain carbon surplus for growth and reproduction and the contribution to carbon and nitrogen recycling of these two species, we also determined their basal metabolism and excretion rates. The experiments conducted during summers 2002, 2003, and 2004 indicate that P. avirostris grazed mostly upon small flagellates, dinoflagellates, and diatoms, whereas O. nana had a narrower prey range, selecting motile organisms such as ciliates and occasionally dinoflagellates. The grazing impact of both species accounted, on average, for <10% of the standing stock of the microbial groups considered. In spite of the oligotrophic conditions, the feeding activity of P. avirostris is in general sufficient to compensate basal metabolism and allows a surplus for growth and reproduction. This was not the case for O. nana, its daily rations being often lower than the carbon basal demands. Regarding excretion rates, both species presented different N:P excretion ratios, the ones of O. nana falling within values typical for copepods, whereas the absence of detectable phosphorus excretion by P. avirostris implied an unbalance recycling with respect to typical Redfield ratio composition of marine seston.     

Environmental health, development and economic empowerment of rural women in Nigeria

Sustainable development is a process that has social, cultural, economic and ecological dimensions. The necessity of improving the quality of life of rural women in terms of socio-economic aspects in developing countries like Nigeria is the aim of this study. The study was carried out in four villages of Tonkere district (Okeake, Abagboro, Elefon and Akiri), situated on expansive university land at Ile-Ife and typical of rural settings in Nigeria. Data were generated from group meetings, local government and individual interviews and surveys. In rural Nigeria, women’s essential contributions to overall environmental health, development and economy are negatively influenced by domestic tasks such as gathering of fuel woods and biomass for cooking. In reality, wood burning, kerosene stoves, and open fireplaces emit significant quantities of known health-damaging pollutants. The significant emissions of health-damaging pollutants per unit activity, combined with daily use in close proximity to rural human populations mean household biomass fuel use exposes total population to important pollutants resulting in ill-health and premature dead. Application of solar energy collectors and hosts of solar devices is an alternative energy sources in rural areas that could best improve women’s health, socially and economically, and positively add to ecological dimensions. Readers should send their comments on this paper to: BhaskarNath@aol.com within 3 months of publication of this issue.     

Photocatalytic degradation of the diuron pesticide

The occurrence of chlorinated pesticides in wellwaters is a major problem of public health in Ivory Coast and other African countries. Here, we studied the photocatalytic degradation of the pesticide diuron in aqueous solution in presence of two commercial TiO₂ catalysts, P25 and PC500. The capacity of diuron adsorption at the TiO₂ surface is lower for both photocatalysts. The efficiency of photocatalytic degradation of diuron, it is higher using P25 Degussa than PC500 Millenium TiO₂ catalyst.