A census of ungulates was carried out in May 2002 in the Haut Niger National Park, Republic of Guinea. The study site was subdivided into three census blocks in which a total 111 transects (total length = 838.24 km) were censused once by one observer. Densities were estimated using DISTANCE analysis. We observed a total of 10 species of ungulates (nine Bovidae and one Suidae). Maxwell's duiker Cephalophus maxwelli had the highest density (3.69 individuals km -2 ) followed by the red-flanked duiker Cephalophus rufilatus (2.61 individuals km -2 ), whereas the buffalo Syncerus caffer had the lowest density (0.34 individuals km -2 ). Compared to a census in 1997, the abundance of red-flanked and Maxwell's duikers significantly decreased (by c. 50%) whereas that of other species remained stable or increased. This variation may possibly be explained by a change in the hunting pattern in the area, which shifted from large-scale hunting by large groups of hunters from outside the area before the Park's creation, to small-scale poaching by local hunters. The Park includes a diversity of ungulate species and harbours populations of ungulates that are important at both national and regional levels. We recommend therefore that the Park should be considered a key area for the conservation of ungulates in West Africa.

the displacement of species from equatorial latitudes to temperate locations following the increase in sea surface temperatures is among the significant reported consequences of climate change. Shifts in the distributional ranges of species result in fish communities tropicalisation, i.e., high latitude colonisations by typically low latitude distribution species. these movements create new interactions between species and new trophic assemblages. the Senegal seabream, Diplodus bellottii, may be used as a model to understand the population genetics of these invasions. in the last decades, this species has undergone an outstanding range expansion from its African area of origin to the Atlantic coast of the iberian peninsula, where now occurs abundantly. Mitochondrial and nuclear markers revealed a striking high haplotypic nucleotide and genetic diversity values, along with significant population differentiation throughout the present-day geographical range of the Senegal seabream. These results are not consistent with the central-marginal hypothesis, nor with the expectations of a leptokurtic distribution of individuals, as D. bellottii seems to be able to retain exceptional levels of diversity in marginal and recently colonised areas. We discuss possible causes for hyperdiversity and lack of geographical structure and subsequent implications for fisheries. Tropicalisation, the displacement of species from equatorial latitudes to temperate locations, is one of the major reported consequences of climate changes 1-3. The increase of sea surface temperatures (SSTs) in the last decades has promoted shifts in the distributional ranges of species (e.g., 4,5) with individuals moving into areas best corresponding to their physiological optimum. Additionally, the ability of a species to colonise new habitats is influenced by oceanographic currents, the existence of adequate resource availability (i.e., habitat and food) and life-history patterns (e.g., number of eggs produced, age or parental care). These movements lead to the colonization of more poleward habitats by low latitude species, and create new interactions between species and new trophic assemblages. In commercial species, these shifts due to climate change can be magnified by fishing pressures, as reported for the North Sea cod (e.g., 6). Poleward colonization by organisms with a typically equatorial distribution was described almost three decades ago for terrestrial organisms in association with postglacial recolonisation routes (e.g., 7-10). As a general rule, organisms follow a leptokurtic distribution type, in which the majority of individuals stay at or near the original area, and only a fraction disperse to longer distances. This range extension is usually done in a steppingstone manner, implying that each settlement has fewer individuals compared with the previous one. Theoretically, this process corresponds to multiple successive genetic founder events associated with the corresponding genetic implications of the downsize in the effective population num...

This work was carried out to study the seasonal occurrence of cyanobacteria and their microcystin-LR in water column of Foum-Gleita reservoir (Mauritania). Limnological and biological factors were investigated at three depths (surface, -3, and -6 m) in this reservoir during a full year. Nutrients were analyzed by Spectrophotometry, phytoplankton was analyzed by Inverted Microscopy, microsystins were analyzed by High Performance Liquid Chromatography-tandem Mass Spectrometry and environmental factors relationships were analyzed by Pearson's correlation and Multiple Linear Regression. Physicochemical analyzes have shown that this reservoir is hypereutrophic with dissolved inorganic nitrogen and total phosphorus concentrations relatively high, varying from 1.39 to 6.53 and 0.21 to 0.57 mg/L, respectively. Annual surface water temperature was exceptionally high (27.8 ± 3.6°C), characterizing of a Sahelian climatic conditions. Phytoplankton analyzes have shown dominance of two toxic cyanobacteria species Microcystis aeruginosa and Dolichospermum os-aquae during warm season (May-September). Microcystins analysis revealed presence of only most toxic variant, microcystin-LR. Microcystin-LR concentration in the surface water samples, during cyanobacterial blooms, was consistently high (5.638 µg/L), exceeding 5-times the World Health Organization drinking water limit (1 µg/L), however, it was much lower (0.83 µg / L) at depth (-6 m). Analysis of environmental factors relationships showed that the most in uential factors on abundance of Microcystis aeruginosa and Dolichospermum os-aquae and variability of microcystin-LR concentrations were total phosphorus, dissolved inorganic nitrogen, iron, temperature and pH. Finally, the study clearly demonstrated need for regular monitoring of cyanobacteria and cyanotoxins in the waters of studied reservoir.

This work was carried out to study the seasonal occurrence of cyanobacteria and their microcystin-LR in water column of Foum-Gleita reservoir (Mauritania). Limnological and biological factors were investigated at three depths (surface, -3, and -6 m) in this reservoir during a full year. Nutrients were analyzed by Spectrophotometry, phytoplankton was analyzed by Inverted Microscopy, microsystins were analyzed by High Performance Liquid Chromatography-tandem Mass Spectrometry and environmental factors relationships were analyzed by Pearson's correlation and Multiple Linear Regression. Physicochemical analyzes have shown that this reservoir is hypereutrophic with dissolved inorganic nitrogen and total phosphorus concentrations relatively high, varying from 1.39 to 6.53 and 0.21 to 0.57 mg/L, respectively. Annual surface water temperature was exceptionally high (27.8 ± 3.6°C), characterizing of a Sahelian climatic conditions. Phytoplankton analyzes have shown dominance of two toxic cyanobacteria species Microcystis aeruginosa and Dolichospermum flos-aquae during warm season (May-September). Microcystins analysis revealed presence of only most toxic variant, microcystin-LR. Microcystin-LR concentration in the surface water samples, during cyanobacterial blooms, was consistently high (5.638 µg/L), exceeding 5-times the World Health Organization drinking water limit (1 µg/L), however, it was much lower (0.83 µg / L) at depth (-6 m). Analysis of environmental factors relationships showed that the most influential factors on abundance of Microcystis aeruginosa and Dolichospermum flos-aquae and variability of microcystin-LR concentrations were total phosphorus, dissolved inorganic nitrogen, iron, temperature and pH. Finally, the study clearly demonstrated need for regular monitoring of cyanobacteria and cyanotoxins in the waters of studied reservoir.

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Excess phosphorus and nitrogen inputs into freshwater ecosystems is one of the main causes of expansion of harmful cyanobacterial blooms worldwide. This work was conducted to study the impacts of phosphorus leaching from the exploitation of phosphate mines present in the watershed of Foum-Gleita Reservoir (Mauritania) on the water quality and its major contribution to the proliferation of harmful cyanobacteria throughout the year. The physicochemical parameters, the occurrence and abundance of phytoplankton (including cyanobacteria), and the microcystins concentration were monitored monthly from September 2017 to August 2018. The relationships between limnological and biological variables were explored by using Pearson's correlation and forward stepwise multiple linear regression (MLR) analysis. Microcystins were detected by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). Our results showed that this reservoir can be classified as hypereutrophic throughout the year and that Microcystis aeruginosa (M. aeruginosa) and Dolichospermum flos-aquae (D. flos-aquae) were dominant species during the rainy season (July-September), and only the congener microcystin-LR (MC-LR) was detected with a peak at 3.55 µg L−1. Pearson's correlation and MLR analysis showed that water temperature pH, phosphorus, nitrogen, and iron concentrations were the most important variables accounting for M. aeruginosa and D. flos-aquae abundance and MC-LR concentration. Our study provides new insight into the effects of moderate nitrogen concentrations on phytoplankton community composition with dominance of the cyanobacteria phylum in phosphorus-rich freshwater ecosystems.

The fishing grounds off the coast of West Africa are among the most productive in the world. Catches in the area in 1970 were in excess of 2 million tons, an increase of about 100% over 1960s catch. Of this only a third was caught by canoes and fleets bordering the region, the rest by an increasing number of large vessels from countries outside Africa.Fishing is still a subsistence activity in all coastal districts and locally based modern vessels are few. Although fish processing industries have been developed in several countries of the region they often remain at a low level of production because of insufficient supply of raw material.Fish consumption in the area — marine and fresh water fish — is estimated at about 1 million tons for a population of 150 million, including the landlocked countries of the Gulf of Guinea. Although imports supply 20% of the fish consumed in the area, there is a deficit of half a million tons. This deficit could well reach 1 million tons in the course of the next decade under the combined pressure of population growth and rising incomes.The uneven distribution of the producing areas and the general demand for fish suggests a potential for a large expansion of interregional trade. The need for the coastal states to develop their fisheries and fishery industries is obvious.The rapid increase of the catch by foreign fleets is causing a number of West African countries to extend their territorial waters beyond the 12-mile limit. This, in turn, is inducing foreign concerns to seek cooperation with the coastal countries. A greater participation of these countries in the exploitation of the resources of their continental shelf should result from the new strategy.In view of the low stage of development in the area an integrated policy for development is needed. This would cover small craft and large vessels, fish processing and marketing, resources assessment and monitoring, aquaculture and training, at all levels in fisheries. Such a strategy is outlined in the paper.

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