The diversity of benthic macroinvertebrates in the Upper (Zone 1) and Middle Thames Estuary (Zone... more The diversity of benthic macroinvertebrates in the Upper (Zone 1) and Middle Thames Estuary (Zone 2) and its associated tributaries, creeks and dock basins was studied using the commonly used hand picking, kick-sampling, core-sampling and wall scraping (barking) methods to examine diversity similarity and differences in macroinvertebrates assemblages between them. Population densities, species lists, densities diversity, and similarity measures were used to analyse the macroinvertebrate dataset obtained from the sorting, identification and counting of the invertebrate species. Results suggested that the upper estuary sites produced the largest number of species/families and middle estuary and creek sites produced the largest number of individuals but the lowest number of species. The Royal dock basins had specialised benthic invertebrate groups, whilst the East India Dock basin had benthic macroinvertebrates composition similar to that of the main river. The mudflat of the mid estuary creeks display very high abundances and dominances by oligochaete and polychaete worms; and their central channels by freshwater species (mainly of upstream of the tributary origin). The study also indicated that habitats with similar physical and other environmental conditions yielded similar macroinvertebrate assemblages.
The stomach contents of 720 individuals belonging to twelve fish species were examined in order t... more The stomach contents of 720 individuals belonging to twelve fish species were examined in order to investigate ontogenetic, seasonal and spatial changes in feeding strategy in the Upper and Middle Thames Estuary (Zones 1 and 2 respectively). 0+ year class consumed a smaller range of food items than the 1+. 1+ year classes consumed a reduced range of food items in winter than in the summer. The more generalist feeders comprising perch, eel, smelt, sea bass and three-spine stickleback consumed a greater range of food items. There were variations in food availability and species feeding selectivity( . Diet overlap values, between all species as measured using Schoener’s index ( were very high regardless of ontogeny, seasonal changes or the spatial distribution of the individuals and, ranged from 0.89-1.00. Species tendency to be more generalist (diet width, ) was lowest during ontogeny and winter and was highest in the summer.
The stomach contents of 720 individuals belonging to twelve fish species were examined in order t... more The stomach contents of 720 individuals belonging to twelve fish species were examined in order to investigate ontogenetic, seasonal and spatial changes in feeding strategy in the Upper and Middle Thames Estuary (Zones 1 and 2 respectively). 0+ year class consumed a smaller range of food items than the 1+. 1+ year classes consumed a reduced range of food items in winter than in the summer. The more generalist feeders comprising perch, eel, smelt, sea bass and three-spine stickleback consumed a greater range of food items. There were variations in food availability and species feeding selectivity (. Diet overlap values, between all species as measured using Schoener’s index ( were very high regardless of ontogeny, seasonal changes or the spatial distribution of the individuals and, ranged from 0.89-1.00. Species tendency to be more generalist (diet width, ) was lowest during ontogeny and winter and was highest in the summer.
The diversity of benthic macroinvertebrates in the Upper (Zone 1) and Middle Thames Estuary (Zone... more The diversity of benthic macroinvertebrates in the Upper (Zone 1) and Middle Thames Estuary (Zone 2) and its associated tributaries, creeks and dock basins was studied using the commonly used hand picking, kick-sampling, core-sampling and wall scraping (barking) methods to examine diversity similarity and differences in macroinvertebrates assemblages between them. Population densities, species lists, densities diversity, and similarity measures were used to analyse the macroinvertebrate dataset obtained from the sorting, identification and counting of the invertebrate species. Results suggested that the upper estuary sites produced the largest number of species/families and middle estuary and creek sites produced the largest number of individuals but the lowest number of species. The Royal dock basins had specialised benthic invertebrate groups, whilst the East India Dock basin had benthic macroinvertebrates composition similar to that of the main river. The mudflat of the mid estuary creeks display very high abundances and dominances by oligochaete and polychaete worms; and their central channels by freshwater species (mainly of upstream of the tributary origin). The study also indicated that habitats with similar physical and other environmental conditions yielded similar macroinvertebrate assemblages.
The stomach contents of 720 individuals belonging to twelve fish species were examined in order t... more The stomach contents of 720 individuals belonging to twelve fish species were examined in order to investigate ontogenetic, seasonal and spatial changes in feeding strategy in the Upper and Middle Thames Estuary (Zones 1 and 2 respectively). 0+ year class consumed a smaller range of food items than the 1+. 1+ year classes consumed a reduced range of food items in winter than in the summer. The more generalist feeders comprising perch, eel, smelt, sea bass and three-spine stickleback consumed a greater range of food items. There were variations in food availability and species feeding selectivity( . Diet overlap values, between all species as measured using Schoener’s index ( were very high regardless of ontogeny, seasonal changes or the spatial distribution of the individuals and, ranged from 0.89-1.00. Species tendency to be more generalist (diet width, ) was lowest during ontogeny and winter and was highest in the summer.
The stomach contents of 720 individuals belonging to twelve fish species were examined in order t... more The stomach contents of 720 individuals belonging to twelve fish species were examined in order to investigate ontogenetic, seasonal and spatial changes in feeding strategy in the Upper and Middle Thames Estuary (Zones 1 and 2 respectively). 0+ year class consumed a smaller range of food items than the 1+. 1+ year classes consumed a reduced range of food items in winter than in the summer. The more generalist feeders comprising perch, eel, smelt, sea bass and three-spine stickleback consumed a greater range of food items. There were variations in food availability and species feeding selectivity (. Diet overlap values, between all species as measured using Schoener’s index ( were very high regardless of ontogeny, seasonal changes or the spatial distribution of the individuals and, ranged from 0.89-1.00. Species tendency to be more generalist (diet width, ) was lowest during ontogeny and winter and was highest in the summer.
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