An investigation into the relationship between temperature and the nutrients (,, and ) in pelagial primary productivity of the middle reaches of Otamiri River in Owerri, Southeastern Nigeria was carried out between Oc...An investigation into the relationship between temperature and the nutrients (,, and ) in pelagial primary productivity of the middle reaches of Otamiri River in Owerri, Southeastern Nigeria was carried out between October and November, 2018 at ten sampling points (OTP 1-OTP 10). The estimation of productivity was made with the light and dark bottle technique. Maximum yields in Gross Primary Productivity (GPP) (0.8738 mgCL-1d-1), Net Primary Productivity (NPP) (0.8513 mgCL-1d-1), as well as Community Respiration (CR) (0.1613 mgCL-1d-1) were recorded at OTP 3, OTP 3 and OTP 8 respectively that had more vegetation covers than in segments without cover. GPP is correlated withions (r = 0.400),ions (r = 0.418), and water temperature (r = 0.379) (p 0.05), while CR is correlated with ions (r = 0.500) (p 0.01). The variability of GPP increased mildly with increasing temperature and the nutrients;with predicted regression model productivities of 0.1388, 0.5621, and 0.6066 mgCL-1d-1, corresponding with mean values of 28.41℃, 0.33 mg/L, 1.04 mg/L and 10.25 mg/L recorded for temperature,,, and ions concentrations. Mean GPP was estimated to result in a comparatively low annual productivity of 188.75 mgCL-1yr-1. Conservation and restoration of riparian vegetation covers in watershed corridors of the river for optimal driver roles were recommended.展开更多
Increasing rate of consumption of the common African catfish, Clarias gariepinus, a popular delicacy in Delta State, Nigeria has raised worries about the safety of health of consumers in the face of perceived rising i...Increasing rate of consumption of the common African catfish, Clarias gariepinus, a popular delicacy in Delta State, Nigeria has raised worries about the safety of health of consumers in the face of perceived rising input of recalcitrant pollutants such as the heavy metals in aquatic habitats. This research investigated the presence and levels of Zn in muscle and brain tissues of C. gariepinus sourced from selected markets in Delta State. Replicate adult fish samples were obtained from seven market locations in Oleh, Asaba, Ekpan, Ogwashi-Ukwu, Okere, Abraka and Ughelli towns, labeled and taken to the laboratory in iced coolers. The presence and levels of the heavy metal were determined spectrophotometrically. Concentrations ranged from 0.015 - 0.19 (0.09 ± 0.02) mg/kg d.w. in muscle and 0.035 - 0.36 (0.16 ± 0.03) mg/kg d.w. in brain tissues, even as accumulation levels differed significantly (t = 0.005) between the tissues at p < 0.05. There was also significant locational heterogeneity in accumulations of the metal [F<sub>(100.97)</sub> > F<sub>crit(4.02)</sub>] at the 95% confidence limit;with least accumulation of 0.03 (±0.01) mg/kg d.w. recorded in fish samples obtained from Ughelli and maximum accumulation of 0.28 (±0.07) mg/kg d.w. recorded in those obtained from Oleh locations. However, levels were below the Food and Agricultural Organization and World Health Organization acceptable limits for Zn in edible fish. Results revealed that lipophilic brain tissues accumulated more heavy metal than muscle tissues. Since accumulation levels were low, they do not currently constitute public health risks to consumers in Delta State.展开更多
文摘An investigation into the relationship between temperature and the nutrients (,, and ) in pelagial primary productivity of the middle reaches of Otamiri River in Owerri, Southeastern Nigeria was carried out between October and November, 2018 at ten sampling points (OTP 1-OTP 10). The estimation of productivity was made with the light and dark bottle technique. Maximum yields in Gross Primary Productivity (GPP) (0.8738 mgCL-1d-1), Net Primary Productivity (NPP) (0.8513 mgCL-1d-1), as well as Community Respiration (CR) (0.1613 mgCL-1d-1) were recorded at OTP 3, OTP 3 and OTP 8 respectively that had more vegetation covers than in segments without cover. GPP is correlated withions (r = 0.400),ions (r = 0.418), and water temperature (r = 0.379) (p 0.05), while CR is correlated with ions (r = 0.500) (p 0.01). The variability of GPP increased mildly with increasing temperature and the nutrients;with predicted regression model productivities of 0.1388, 0.5621, and 0.6066 mgCL-1d-1, corresponding with mean values of 28.41℃, 0.33 mg/L, 1.04 mg/L and 10.25 mg/L recorded for temperature,,, and ions concentrations. Mean GPP was estimated to result in a comparatively low annual productivity of 188.75 mgCL-1yr-1. Conservation and restoration of riparian vegetation covers in watershed corridors of the river for optimal driver roles were recommended.
文摘Increasing rate of consumption of the common African catfish, Clarias gariepinus, a popular delicacy in Delta State, Nigeria has raised worries about the safety of health of consumers in the face of perceived rising input of recalcitrant pollutants such as the heavy metals in aquatic habitats. This research investigated the presence and levels of Zn in muscle and brain tissues of C. gariepinus sourced from selected markets in Delta State. Replicate adult fish samples were obtained from seven market locations in Oleh, Asaba, Ekpan, Ogwashi-Ukwu, Okere, Abraka and Ughelli towns, labeled and taken to the laboratory in iced coolers. The presence and levels of the heavy metal were determined spectrophotometrically. Concentrations ranged from 0.015 - 0.19 (0.09 ± 0.02) mg/kg d.w. in muscle and 0.035 - 0.36 (0.16 ± 0.03) mg/kg d.w. in brain tissues, even as accumulation levels differed significantly (t = 0.005) between the tissues at p < 0.05. There was also significant locational heterogeneity in accumulations of the metal [F<sub>(100.97)</sub> > F<sub>crit(4.02)</sub>] at the 95% confidence limit;with least accumulation of 0.03 (±0.01) mg/kg d.w. recorded in fish samples obtained from Ughelli and maximum accumulation of 0.28 (±0.07) mg/kg d.w. recorded in those obtained from Oleh locations. However, levels were below the Food and Agricultural Organization and World Health Organization acceptable limits for Zn in edible fish. Results revealed that lipophilic brain tissues accumulated more heavy metal than muscle tissues. Since accumulation levels were low, they do not currently constitute public health risks to consumers in Delta State.
