Oxbow Lake

This study was carried out to assess the socio-economic status of fishermen of the Marjat Baor at Kaligonj of Jhenidah district. Fifty fishermen from 50 families were interviewed. Results revealed that 94% respondents were married and age varied between 30 and 45 years. Almost all the fishermen were Hindus (96%). Most of the people of the community were illiterate (60%) and among all of the school going children (58%) were boys and (42%) were girls. Above fifty percent people lived in nuclear family. 40% people lived in earthen house, constructed by grass leaves and mud. Only a few (18%) of them were found to be use electricity. Primary occupation of 60% respondents was fishing and few were also involved in agriculture. They were often found to suffer from various diseases due to lack of pure drinking water. Majority of them got fever and receive treatment from quack. Only twelve percent (12%) women were engaged in making nets for fishing. Annual household income of maximum benefici...

Objective: Evaluation of the biological community of a water body provides sensitive and cost effective means of assessing its water quality. Aquatic macrophytes diversity and its role in understanding the oxbow lake ecosystem dynamics have tremendous significance. The study is aimed for quantitative biomonitoring the ecological quality through macrophytes diversity. Methods: A survey of macrophytes communities of freshwater Chhariganga oxbow lake of West Bengal in eastern India along with analysis of diversity indices, dominance trends with importance value index (IVI) and composition trends was carried out. Results: Estimating annual average IVI values, we found that emergent (154.91±12.59) were dominant, followed by the free-floating (78.22±25.12), submerged (37.78±11.82) and rooted floating-leaved genus (29.09±13.84). Among emergent, Cynodon sp was the most dominant during pre monsoon and post monsoon and Ipomoea sp during monsoon. Among the free-floating genus, Eichhornia sp was highly dominant throughout the year while Lemna sp topped the group during pre monsoon. Among the submerged genus, Hydrilla sp was observed to be the most dominant genus throughout the year. Among rooted floating-leaved Nymphaea sp was highly dominant during monsoon and post monsoon and Brasenia sp during pre monsoon. Highest values of density (120no/m 2), average area coverage (69.34%) and average wet biomass (1816.72 g/m 2) were observed during post monsoon while lowest values of density (27no/m 2), average area coverage (38.95%) and average wet biomass (281.78g/m 2) were estimated during the monsoon. We found genus richness values higher during post (44) and pre (36) monsoon and lower in monsoon (22) with mean genus Evenness value of 0.79±0.05. In our study lower average diversity values of Shannon Wiener index (2.74 ±0.36) and Simpson index (0.90±0.04) throughout the year render poor to moderate pollution status to the oxbow lake while presence of certain bio-indicators species like

Oxbow lakes are semi-closed water bodies (locally called Baor) occupied by dead channels of rivers. To evaluate the existing status of Baor fisheries two Baors (Baluhor and Nasti Baor) of different management practices in south-western Bangladesh was selected. Both primary and secondary data were collected from March to December 2018. Management of Baluhor and Nasti Baor were enforced by the Department of Fisheries (DoF) and fishers’ community themselves (CBFM) respectively. Fishers’ involvement with fishing activities had restricted access to both study Baor areas. The commonly cultured species were Labeo rohita, Catla catla, Hypophthalmichthys molitrix, Ctenopharyngodon idella, Cirrhinus cirrhosus, Mylopharyngodon piceus, and Cyprinus carpio, locally called “Raja Mach”. Various non-stocked fishes were also found in both Baors that reproduced naturally, locally called “Rani Mach”. In Nasti Baor, fish was harvested (Both Raja and Rani Mach) three to four times a year while it was tw...

Palaeoenvironmental study in the downstream basin of the Loire River: « la Grande Prée de Varades » (Loire-Atlantique, France)

As part of a project to restore water to an old oxbow lake of the Loire River (La Boire Torse at Varades, Loire-Atlantique, France), a palynological coring was conducted in the alluvial plain for a palaeoenvironmental reconstruction in order to better understand the evolution and history of this oxbow lake during the past 5000 years, the sequence of which started at the Subboreal, during the second half of the Middle Neolithic. During this period, the forest ecosystem is well developed on the hillsides, but much of the deforestation clearly accompanies the establishment of a cultural and pastoral context. In the wetland area, the marsh is dominated by sedge bogs where birch and alder grow. The Late Neolithic appears to be dominated by pastoral practices. During the Bronze Age and Iron Age, human pressure is increasing on the forest system and starting from the beginning of the Gallo-Roman period, the landscape is very open on both the hillsides as well as in the alluvial plain. The Early Middle Ages is marked by hydrological changes in the environment which could be connected, in all likelihood, to changes in land use or management. The top of the clay filling corresponds to the input of reworked sediment, from the excavation of the backwaters around 1200 BP or later. The 4 top metres of sand, covering the muddy deposits, indicate a change in the fluvial dynamic with an active hydrology, after the excavation of the oxbow lake.

Dans le cadre de la restauration d’un bras mort de la Loire (la Boire Torse à Varades, Loire-Atlantique) pour sa remise en eau, un sondage palynologique a été réalisé dans la plaine alluviale, en vue d’une reconstitution paléoenvironnementale, permettant de mieux comprendre l’évolution et l’histoire de cette boire depuis un peu plus de 5000 ans, la séquence débutant au Subboréal, durant la seconde moitié du Néolithique moyen. Pendant cette période, l’écosystème forestier est bien développé sur les coteaux, mais les déboisements s’accompagnent nettement de la mise en place d’un contexte cultural et pastoral. Dans la zone humide, le marécage est dominé par la magnocariçaie dans laquelle s’installent bouleau et aulne. Le Néolithique final semble dominé par les pratiques pastorales. À l’Âge du Bronze et à l’Âge du Fer, la pression humaine se renforce sur le système forestier et dès le début de la période gallo-romaine, le paysage est très ouvert aussi bien sur les coteaux que dans la plaine alluviale. Le haut Moyen Âge est marqué par des changements hydrologiques du milieu que l’on peut relier, selon toute vraisemblance, à des modifications d’exploitation ou de gestion du terroir. Le sommet  du remplissage argileux correspond à l’apport de sédiments remaniés, provenant du creusement de la boire vers 1200 BP ou postérieurement. Les quatre mètres  supérieurs de sable, recouvrant les dépôts vaseux, dénotent un changement de dynamique fluviale avec une hydrologie active, postérieurement au creusement de la boire.

The malacofauna of two profiles of deposits filling palaeomeanders of the Bug River Valley was studied. The first one (Zaczopki) represents an older phase of the valley development corresponding with the Early Holocene or even with the Late Glacial. Its assemblage contains numerous shells of cold-tolerant species. The second profile is situated near the village Woroblin. It represents a younger stage of the valley evolution (uppermost part of the Middle Holocene and Late Holocene). The mollusc fauna is typical of shallow and overgrown, stagnant water bodies. The sequences of mollusc aasemblages from both profiles characterise the development of these reservoirs, corresponding with climatic changes and differences in fluvial activity of the Bug River during the Holocene.

Oxbow lakes are semi-closed water bodies (locally called Baor) occupied by dead channels of rivers. To evaluate the existing status of Baor fisheries two Baors (Baluhor and Nasti Baor) of different management practices in south-western Bangladesh was selected. Both primary and secondary data were collected from March to December 2018. Management of Baluhor and Nasti Baor were enforced by the Department of Fisheries (DoF) and fishers’ community themselves (CBFM) respectively. Fishers’ involvement with fishing activities had restricted access to both study Baor areas. The commonly cultured species were Labeo rohita, Catla catla, Hypophthalmichthys molitrix, Ctenopharyngodon idella, Cirrhinus cirrhosus, Mylopharyngodon piceus, and Cyprinus carpio, locally called “Raja Mach”. Various non-stocked fishes were also found in both Baors that reproduced naturally, locally called “Rani Mach”. In Nasti Baor, fish was harvested (Both Raja and Rani Mach) three to four times a year while it was tw...

This study was carried out to assess the socioeconomic status of fishermen of the Marjat Baor at Kaligonj of Jhenidah district. Fifty fishermen from 50 families were interviewed. Results revealed that 94% respondents were married and age varied between 30 and 45 years. Almost all the fishermen were Hindus (96%). Most of the people of the community were illiterate (60%) and among all of the school-going children (58%) were boys and (42%) were girls. Above fifty percent people lived in a nuclear family. 40% of people lived in the earthen house, constructed by grass leaves and mud. Only a few (18%) of them were found to use electricity. The primary occupation of 60% of respondents was fishing and few were also involved in agriculture. They were often found to suffer from various diseases due to lack of pure drinking water. Majority of them got a fever and receive treatment from quack. Only twelve percent (12%) women were engaged in making nets for fishing. Annual household income of maximum beneficiaries (44%) was below BDT 30,000 and above BDT 50,000 found in only 4% cases. In the present study, educational, organizational, and technical credit support were very crucial to develop their better socioeconomic conditions.