The current rate of exploitation of Bonga by the purse seine fishery in the Cross River Estuary and adjacent coastal waters, Nigeria

Studies were conducted to assess the current level of exploitation of bonga in Cross River Estuary and its adjacent coastal waters. Time series of length-frequency distribution of bonga over 18 months time scale was carried out. FAO-ICLARM Fish Stock Assessment Tool (FiSAT) was employed to determine the population and growth parameters. The instantaneous rates of total mortality,fishing mortality and natural mortality were 6.9 per year, 5.30 per year, and 1_61per year respectively. The exploitation rate was 0.77. This implies that the stock of Efimbriata of Cross River Estuary is experiencing excessive fishing pressure. This proposition is accentuated by the downward trend in bonga abundance throughout the study period. The over fishing is attributed to the Ghanaian purse seining, which even penetrates into the bonga nursery in the inner Cross River estuary for destructive fishing. This phenomenon has exerted adverse socio-economic impact on thelife of the people of lower Cross River basin whose main source of livelihood is bonga fishery. We propose a ban on the purse seine fishery in Cross River Estuary

Length frequency distribution of Ethmalosa fimbriata (Bowdich) in cross River Estuary and Adjacent Coastal waters

Studies on the length distribution of bonga, Ethmalosa fimbriata, in the Cross River estuary and adjacent coastal waters were conducted from October 1999 to December 2000. A total of 15,182 specimens of bonga from gill nets, purse seine and boat seine fisheries were measured. Post-larvae measuring between 2 cm and 9 cm were found in the lower estuary with a modal length of 4 cm. Juveniles from gill net fishery ranged in length from 8 cm to 20 cm with a modal length of 13cm. Adults and sub-adults ranging in size from 16 cm to 33 cm were caught from the coastal waters alongside the juveniles, by the purse seine fishery. Two modal lengths of 17 cm and 25 cm were observed in the coastal waters. Three modal length classes were observed in the catches from the Cross River estuary and adjacent coastal waters: these are 4 cm, 13 cm and 25 cm. It is concluded that the Cross River estuary is a nursery ground for bonga, Ethmalosa fimbriata. Key Words: Ethmalosa fimbriata, length distribution, Cross River estuary, coastal waters, nursery. (Global Journal of Pure and Applied Sciences: 2002 8(3): 299-304

Microflora population in mangrove sediments of Cross River estuary

No Abstract.Global Journal of Pure and Applied Sciences Vol. 13 (3) 2007: pp.347-35

The European LGS test facility

International audienceA European Laser Guide Star (LGS) test facility is proposed for the 4.2m William Herschel Telescope (WHT) on La Palma. It will test the next-generation Adaptive Optics (AO) LGS technologies to aid risk mitigation of Extremely Large Telescope (ELT) LGS AO systems. In particular, critical scaling of current LGS AO technologies to ELT dimensions will be tested. For example, experiments addressing increased spot elongation, cone effect and the order of correction required. A pan-European consortium proposes to construct test facility infrastructure on the WHT for a number of risk mitigating experiments. The infrastructure includes the construction of a Nasmyth platform based controlled environment 'Ground-based Adaptive optics Innovative Laboratory' (GRAIL), an experimental test environment 'Testbed integration facility' (TIF) and some common-experiment equipment such as the Common Re-Imaging AO System. Experiments that are proposed for this facility cover the areas of laser technologies, spot elongation, LGS wavefront sensing, parallel launch concepts, Multi-Object AO, atmospheric characterisation, co-phasing and real-time control system risk mitigation

Advanced methods of plant disease detection. A review

International audiencePlant diseases are responsible for major economic losses in the agricultural industry worldwide. Monitoring plant health and detecting pathogen early are essential to reduce disease spread and facilitate effective management practices. DNA-based and serological methods now provide essential tools for accurate plant disease diagnosis, in addition to the traditional visual scouting for symptoms. Although DNA-based and serological methods have revolutionized plant disease detection, they are not very reliable at asymptomatic stage, especially in case of pathogen with systemic diffusion. They need at least 1–2 days for sample harvest, processing, and analysis. Here, we describe modern methods based on nucleic acid and protein analysis. Then, we review innovative approaches currently under development. Our main findings are the following: (1) novel sensors based on the analysis of host responses, e.g., differential mobility spectrometer and lateral flow devices, deliver instantaneous results and can effectively detect early infections directly in the field; (2) biosensors based on phage display and biophotonics can also detect instantaneously infections although they can be integrated with other systems; and (3) remote sensing techniques coupled with spectroscopy-based methods allow high spatialization of results, these techniques may be very useful as a rapid preliminary identification of primary infections. We explain how these tools will help plant disease management and complement serological and DNA-based methods. While serological and PCR-based methods are the most available and effective to confirm disease diagnosis, volatile and biophotonic sensors provide instantaneous results and may be used to identify infections at asymptomatic stages. Remote sensing technologies will be extremely helpful to greatly spatialize diagnostic results. These innovative techniques represent unprecedented tools to render agriculture more sustainable and safe, avoiding expensive use of pesticides in crop protection