Environment

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Detection and spatio-temporal variation of marine heatwaves in the Gulf of Guinea, Nigeria
(Academic Journals (Journal of Oceanography and Marine Science), 2019-09-04) Asuquo, Francis Emile; Oghenechovwen, Oghenekevwe Christopher
Time series analyses spanning 30 years (1988 - 2017) on spatial and temporal variations in sea surface temperatures reveal the occurrence of marine heatwaves (MHWs) within the Nigerian segment of the Gulf of Guinea. For specific focus, three locations were also chosen along Nigeria’s coastal zone, namely Lagos lagoon (western region), the Niger Delta (Forcados/Central region) and outer Cross River estuary (eastern region). Daily SST data was subjected to MHW detection algorithm, and then examined using Gaussian and Poisson distribution models to delineate the distribution of maximum intensities and frequency of occurrence of these extreme events, respectively. Determining the likelihood difference of maximum intensities of MHWs and the association between MHW count and occurrence year during the period was done using Kruskal-Wallis and Kendall rank correlation tests, respectively. Results show that the entire study area has been experiencing MHWs more frequently in recent decades, with the northwest region having higher counts. Strong seasonality exists, as more MHWs occurred in winter months (October to May). Peak month for MHW occurrence over the entire study area was May. November is shared as a peak month for the three focus coastal locations, although MHWs in Cross River and Niger Delta locations exhibited multi-modal patterns. None of the MHWs in Lagos location was categorized as severe. This study contributes to the World Climate Research Programme Grand Challenge on Weather and Climate Extremes.
Human health risk assessment from heavy metals in three dominant fish species of the Ankobra river, Ghana
(ELSEVIER, 2021-05-24) Effah, Elizabeth; Aheto, Denis Worlanyo; Acheampong, Emmanuel
This study assessed heavy metal contamination of fish and its associated health risk to communities around the Ankobra River in the Western Region of Ghana. Species of fish randomly collected from different sections of the river were analyzed for Cd, Ni, Zn, Pb, Mn, Hg, As, Co and Cr using Atomic Absorption Spectrophotometry. Three commonly consumed fish species, Clarias gariepinus, Sarotherodon melanotheron and Pseudotolithus senegalensis, were analyzed. The health risks were assessed based on the potential non-carcinogenic effect associated with the daily consumption of fish by communities around the river. Concentrations of all the metals were higher in gills than the muscles of all three species. On average, levels of Mn (6.65 ± 7.30 mg.kg􀀀 1), Zn (2.24 ± 1.99 mg.kg􀀀 1) and Hg (3.06 ± 1.53 mg.kg􀀀 1) in all three species were above the permissible limits recommended by the World Health Organization. The health risk estimated for all the heavy metals was < 1, significantly below the ≥ 1 index associated with the incidence of cancer. This suggests that fish species examined in this study pose no significant non-carcinogenic risk and are safe for human consumption.
Implications of overlooked seasonal growth dynamics in tropical fisheries assessment: A test case of an oyster (Crassostrea tulipa) fishery in the Densu Delta, Ghana
(ELSEVIER B.V, 2021-09-09) Osei, Isaac Kofi; Yankson, Kobina; Obodai, Edward Adzesiwor
Tropical fish stocks are perceived not to exhibit seasonality in growth. For this reason the standard von Bertalanffy growth function (VBGF) has been used widely to fit the growth of tropical fish populations compared to the seasonally-oscillating VBGF (soVBGF), which is seldom used in tropical fisheries. To advocate for the use of the soVBGF in assessment of tropical fish stocks, this study compared the outputs of the two methods using ELEFAN_ GA_boot on oysters from the Densu Delta, Ghana. Sampling of mangrove oyster, Crassostrea tulipa covered a period of 12 months and the data were analysed for VBGF growth parameters and its prediction models. The intensity of growth oscillation showed that C. tulipa exhibited seasonal growth (C = 0.50), and the soVBGF fitted the growth of the oyster better than the standard VBGF method. Estimates of some of the stock parameters (t50, tmax, Fcur, Ecur and Ycur) were comparatively higher for the standard VBGF than the soVBGF approach. In both approaches, the oysters were underexploited (Ecur < Emsy). However, unlike the soVBGF method where Fcur < F0.5, the standard method indicated that Fcur > F0.5. In view of the disparities, studies which adopt standard VBGF on tropical stocks that exhibit seasonality would likely generate comparatively higher outputs for relevant biological reference points, which may ultimately mislead management decisions. Given the sedentary nature of oysters which could render the organisms more susceptible to seasonal variations in environmental conditions to show seasonality as observed in this study, we recommend further works on tropical shell- and finfishes to corroborate the current findings or otherwise.
Is the Co-management Approach Effective for Mangrove Conservation in West Africa?
(Research Square, 2021-12-08) Sagoe, Alberta Ama; Mattah, Precious Agbeko Dzorgbe; Salako, Valère Kolawolé
The conservation management literature has recently documented the increasing use of co-management approach to effectively conserve natural resources. Although most research qualify the co-management as highly effective, some authors also reported a number of uncertainties associated with the use of this conservation approach. Using the Mono Transboundary Biosphere Reserve (MTBR) as a case study, this work assessed the effectiveness of the co-management towards mangroves conservation in West Africa. Data were collected in two protected sites of the reserve (one in Togo and the other in Benin). Exploratory sequential mixed method via in-depth interviews (n=17), focus group discussions (n=14), household survey (n=274) and expert-based survey (n=10) were carried out, and subjected to the InVEST-based Habitat Risk Assessment (HRA) model, chi-square test and simple probability of likelihood. Results indicated that under the current co-management regimes, the anthropogenic stressors recorded in the reserve put the entire surface area of mangroves in Benin (100%) under low risk. Contrarily, 42% of the mangrove cover are under low risk and 58% under medium risk in Togo. Local perception also portrayed a large reduction of mangrove degradation in the study sites following the adoption of the co-management approach in the two countries. This study suggests that the implementation of the co-management approach has lowered anthropogenic stressors to mangroves in the reserve. However, there are some peculiar challenges (e.g., financial support provision, regular community engagement), which need to be thoroughly researched and addressed for a more effective conservation of mangroves in the MTBR.
Local uses of mangroves and perceived impacts of their degradation in Grand-Popo municipality, a hotspot of mangroves in Benin, West Africa
(ELSEVIER, 2021-03-06) Gnansounou, Sètondé Constant; Toyi, Mireille; Salako, Kolawolé Valère
Detailed understanding of interactions between humans and their surrounding ecosystems is essential for design- ing sustainable use and management of these ecosystems. Mangroves are one of the most productive ecosystems worldwide, yet amongst the most threatened. This study (1) explored main activities of local communities in re- lationship to mangroves and variation across geographical locations, gender, and age categories, (2) investigated plants and animals used and collected from mangroves and their adjacent areas, and (3) assessed local perception on the impacts of their activities on the degradation of mangroves and potential effects of this degradation on their life attributes (security, income, health and culture). The study was conducted in Grand-Popo municipality, a hotspot of mangroves and the only one coastal municipality embedded in the Mono Transboundary Biosphere Reserve in Benin. Data were collected through individual interviews ( n = 360) in nine villages of the municipality. Results showed that local communities of Grand-Popo practice nine income generating activities (IGA) within mangroves and fishing (31.65%), wood collection (22.73%), Cyperus articulatus collection (21.67%), medicinal plant collection (8.98%), and salt production (5.56%) were frequent. There were important differences across geographical locations, gender, and age categories with regard to used mangrove resources and socio-economic activities. Respondents reported twenty-three fish species, two shrimp species, two crab species and one oys- ter species as fishery resources commonly collected from mangroves. Most interviewees (58.33%) believed that their activities do not negatively impact mangroves despite popular recognition of the dwindling of mangroves’ coverage (75% of respondents). Our findings provide important information on resources collected and used in mangrove ecosystems and highlight strong geographical locations, gender, and age categories variation. Impli- cations for sustainable participative management were discussed.
Long-term spatio-temporal trends in extreme wave events in the Niger delta coastlines.
(ELSEVIER , Continental Shelf Research, 2021-05-28) Osinowo, Ayodotun Adekunle; Popoola, Samuel Olatunde
Wave climate in the marginal seas and estuaries provide baseline information, risk assessments and essential insight into coastal design, structure and engineering projects. This paper investigates the Spatio-temporal trends in extreme Significant Wave Height (SWH) in the Niger Delta coastlines. For the study domain, European Centre for Medium-Range Weather Forecasts (ECMWF) global atmospheric reanalysis ERA-Interim and wave hindcast data covering 37 years (January 1, 1980–December 31, 2016), derived from WAVEWATCH III (WW3) model were used in the analysis. The largest 99th percentile approach was used to analyze extreme SWH values. Results showed near neutral and negative trends over the region. The trends are generally insignificant for the 100-year return period. The sharp variation in extreme SWH between 1998 and 2000 resulted from a strong El Nino and La Nina phenomenon, which is associated with the weakening and strengthening of the West-African Monsoon.
Multiple Antibiotic Resistance-Coliform Bacteria inSomeSelected Fish Farms of the Central Region of Ghana
(Hindawi, 2020-12-08) Adinortey, Cynthia Ayefoumi; Aheto, Denis Worlanyo; Boateng, Alex Asomeni
&is study aimed at assessing the quality of water and fishery products as well as the antibiotic resistance status of some selected fish farms of the Central Region of Ghana. Interview guides were administered to farmers to get data on farming practices and antibiotic use. Total coliform loads of catfish (Clarias gariepinus), tilapia (Oreochromis niloticus), and water samples were determined. Coliforms were identified through various biochemical assays, and their antibiotic resistance patterns were determined. Generally, the total coliform loads of water samples significantly surpassed those of fish samples (p < 0.05). &e maximum and minimum antibiotic resistance percentages were recorded for ampicillin (96.83%) and gentamicin (6.35%), respectively. Although farmers stated that antibiotics were sparingly used, coliform bacteria isolated exhibited various antibiotic resistance patterns. Four out of six fish farms harboured some coliforms with multiple antibiotic resistance (MAR) indices above 0.2, an indication that these bacteria originated from potentially dangerous sources where antibiotics are regularly used.
Socio-ecological analysis of artisanal gold mining in West Africa: A case study of Ghana
(Journal of sustainable mining, 2021-09-30) Takyi, Richard; Hassan, Rasha; Mahrad, Badr El
The surge in artisanal gold mining (AGM) activities and the associated environmental impact in Ghana have elicited several stakeholders' attempts to curb the problem. However, due to little understanding of the underlying issues, these efforts have been ineffective. This study aims to use a socio-ecological framework to analyze drivers of AGMactivities, the environmental pressures, the state change, their impact on human welfare, and the management response as measures (DAPSI(W)R(M)) to the problem. Evaluate AGM's impact on Ghana's ability to achieve the United Nations Sustainable Development Goals (SDGs). Data were collected from relevant literature on the subject and analyzed with the DAPSI(W) R(M) framework. Esteem needs, food, acceptance and friendship, and self-actualization are the main drivers of AGM activities leading to environmental pressures, including abrasion, extraction of living and non-living resources, the introduction of non-synthetic compounds, among others. State changes of the environment resulting fromthe pressures generated by human activitieswere changes in the land and forest cover (1.13%), topography (hills turned into flatland and undulating), and biota. Due to the state in the environment, water quality and availability, agriculture food production, fish yield, food safety, spiritual and cultural loss, death, injury, and health of gold miners and other stakeholders have been affected.
The Tropical Atlantic Observing System
(Frontiers in Marine Science, 2019-05-10) Foltz, G.R.; Brandt, P.; Richter, I.
The tropical Atlantic is home to multiple coupled climate variations covering a wide range of timescales and impacting societally relevant phenomena such as continental rainfall, Atlantic hurricane activity, oceanic biological productivity, and atmospheric circulation in the equatorial Pacific. The tropical Atlantic also connects the southernand northern branches of the Atlantic meridional overturning circulation and receives freshwater input from some of the world’s largest rivers. To address these diverse, unique, and interconnected research challenges, a rich network of ocean observations has developed, building on the backbone of the Prediction and Research Moored Array in the Tropical Atlantic (PIRATA). This network has evolved naturally over time and out of necessity in order to address the most important outstanding scientific questions and to improve predictions of tropical Atlantic severe weather and global climate variability and change. The tropical Atlantic observing system is motivated by goals to understand and better predict phenomena such as tropical Atlantic interannual to decadal variability and climate change; multidecadal variability and its links to the meridional overturning circulation; air-sea fluxes of CO2 and their implications for the fate of anthropogenic CO2; the Amazon River plume and its interactions with biogeochemistry, vertical mixing, and hurricanes; the highly productive eastern boundary and equatorial upwelling systems; and oceanic oxygen minimum zones, their impacts on biogeochemical cycles and marine ecosystems, and their feedbacks to climate.

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