Spatiotemporal spatfall dynamics and prevailing estuarine conditions for optimal oyster (Crassostrea tulipa) spat availability in selected Gulf of Guinea brackish systems

Uncertainties associated with wild harvests of seed and adult oysters due to unknown oceanographic oscillations are a major challenge in oyster fisheries and aquaculture development. In contribution to addressing this challenge, we proffer clarity on the spatiotemporal variations in spatfall (number of spat/m2) of the mangrove oyster Crassostrea tulipa (Lamarck, 1819) in four estuaries along the Gulf of Guinea coast. By monthly deployment of artificial substrates affixed to bamboo racks over 12 months, we find significant differences in spatfall among and within the brackish systems, and across months and seasons. Spatfall regimes were unique in each ecosystem albeit with an overall preponderance of dry season availability of spat. Locations with reef oysters had superior spatfall to mangrove root-adapted-oyster areas. Narkwa, a relatively small lagoon with reef oysters had the highest annual mean spatfall, which was 1.3, 2.5, and 9.8 folds the spatfall in Densu Delta, Benya Lagoon and Whin Estuary, respectively. Spatfall varied significantly by depth as the more frequently exposed top collectors harvested much less spat than submerged collectors. There was a year-round availability of spat, confirming continuous spawning in C. tulipa. Spatfall variability was significantly driven by fluctuations in prevailing dissolved oxygen and salinity. Prevailing dissolved oxygen and salinity levels in the estuaries for optimal spat settlement were 1.68 – 3.40 mg L-1 and 11.00 – 29.33 ppt (parts per thousand), respectively. The findings of this study are recommended as empirical reference points for sustainable seed procurement for aquaculture production and management of C. tulipa fishery in the region of the study

A modeling assessment of geneflow in smallholder agriculture in West Africa

PURPOSE: Small-scale agriculture is an important issue for food security in Africa. In the context of Genetically Modified Organisms, approaches to quantify geneflow in small-scale systems are widely unexplored. We aimed at bridging this gap by contributing to the scientific discussion on the uncertainties of the cultivation of genetically modified (GM) crops in the region. The safety issue is: Would it be possible to withdraw a variety in case that unexpected and undesirable effects occur? e.g. the resistance of pests which make the variety no more useful. METHODS: We used a GIS approach to determine the location of maize cultivation sites, field geometries and applied a model for the calculation of geneflow scenarios. RESULTS: The data revealed that the given cropping density provides optimal conditions for transgene spread, potentially limiting the possibility for coexistence between GM and non-GM fields. On average, we found about 60 fields within a nearest distance of 100 m, and cropping density of 56 fields per square kilometer. The resulting cross-pollination rate from the single GM field into the neighbouring conventional fields was estimated to be about 0.12%. CONCLUSIONS: GM varieties if introduced could remain in cultivation even if their admission has expired or has been retracted. This would be undesirable and could cause long-term, undesirable stacked combination of transgenes which cannot be tested with respect to eventual combinatory effects. These developments pose major challenges for fielder livelihoods, and conservation of maize genetic resources with potentially negative consequences for the African food export sector

Sampling Error and Its Implication for Capture Fisheries Management in Ghana

Capture fisheries in developing countries provide significant animal protein and directly supports the livelihoods of several communities. However, the misperception of biophysical dynamics owing to a lack of adequate scientific data has contributed to the suboptimal management in marine capture fisheries. This is because yield and catch potentials are sensitive to the quality of catch and effort data. Yet, studies on fisheries data collection practices in developing countries are hard to find. This study investigates the data collection methods utilized by fisheries technical officers within the four fishing regions of Ghana. We found that the officers employed data collection and sampling procedures which were not consistent with the technical guidelines curated by FAO. For example, 50 instead of 166 landing sites were sampled, while 290 instead of 372 canoes were sampled. We argue that such sampling errors could result in the over-capitalization of capture fish stocks and significant losses in resource rents

Carbon Stocks Assessment in a Disturbed and Undisturbed Mangrove Forest in Ghana

Mangroves and other blue carbon ecosystems have long been recognised for their carbon sink function, yet the organic carbon stocks of mangroves in many countries in Africa remain to be assessed. This study evaluates the impact of traditional forest conservation on long-term carbon sequestration in a non-degraded (Amanzule) and a degraded (Kakum) mangrove forest system in Ghana (West Africa). The amount of carbon stored in mangrove trees was estimated from diameter-based allometric equations. Tree (above- and below-ground) carbon was ~34-fold higher in the Amanzule forest (mean = 0.89 ± 0.10 t/ha) than in the Kakum forest (mean = 0.026 ± 0.019 t/ha). Soil carbon density was estimated as organic carbon and bulk density at specific depths in both forests. Soil organic carbon density was ~5-fold higher in the Amanzule forest (mean = 2935.79 ± 266 t/ha) than the Kakum forest (mean = 554.01 ± 83 t/ha). The variation in the vertical distribution of soil carbon was not significant in either forest (F = 0.57; p > 0.05). These findings underscore the role of traditional conservation on mangrove carbon stocks and the need to consider the governance of coastal ecosystems when estimating blue carbon

Sampling Error and Its Implication for Capture Fisheries Management in Ghana

Capture fisheries in developing countries provide significant animal protein and directly supports the livelihoods of several communities. However, the misperception of biophysical dynamics owing to a lack of adequate scientific data has contributed to the suboptimal management in marine capture fisheries. This is because yield and catch potentials are sensitive to the quality of catch and effort data. Yet, studies on fisheries data collection practices in developing countries are hard to find. This study investigates the data collection methods utilized by fisheries technical officers within the four fishing regions of Ghana. We found that the officers employed data collection and sampling procedures which were not consistent with the technical guidelines curated by FAO. For example, 50 instead of 166 landing sites were sampled, while 290 instead of 372 canoes were sampled. We argue that such sampling errors could result in the over-capitalization of capture fish stocks and significant losses in resource rents

Carbon Stocks Assessment in a Disturbed and Undisturbed Mangrove Forest in Ghana

Mangroves and other blue carbon ecosystems have long been recognised for their carbon sink function, yet the organic carbon stocks of mangroves in many countries in Africa remain to be assessed. This study evaluates the impact of traditional forest conservation on long-term carbon sequestration in a non-degraded (Amanzule) and a degraded (Kakum) mangrove forest system in Ghana (West Africa). The amount of carbon stored in mangrove trees was estimated from diameter-based allometric equations. Tree (above- and below-ground) carbon was ~34-fold higher in the Amanzule forest (mean = 0.89 ± 0.10 t/ha) than in the Kakum forest (mean = 0.026 ± 0.019 t/ha). Soil carbon density was estimated as organic carbon and bulk density at specific depths in both forests. Soil organic carbon density was ~5-fold higher in the Amanzule forest (mean = 2935.79 ± 266 t/ha) than the Kakum forest (mean = 554.01 ± 83 t/ha). The variation in the vertical distribution of soil carbon was not significant in either forest (F = 0.57; p > 0.05). These findings underscore the role of traditional conservation on mangrove carbon stocks and the need to consider the governance of coastal ecosystems when estimating blue carbon

Local fishery, global commodity: the role of institutions in mediating intersectoral conflict, cooperation, and competition in a globalized fishery

Commons scholarship has improved our understanding of how to govern resources for sustainability. However, it has also been critiqued for its focus on traits (e.g. well-defined system boundaries) that are increasingly threatened by social and environmental trends. Fisheries are a key example of this challenge. While small-scale fisheries are critically important to the diets and livelihoods of millions, industrial fisheries from developed countries now dominate fishing around the world. While these two systems are governed separately, there is substantial overlap between them, conceptualized as the growing influence of globalization on local common pool resource (CPR) systems. One of the most impactful, but least understood consequences of this convergence are the emerging conflicts and competition between small-scale and industrial fisheries. In these systems, the interaction between small-scale CPRs and globalized commodity chains has meant the creation of a new, hybrid resource system, addressed by neither conventional industrial nor traditional small-scale governance approaches. We use empirical data from 396 cases of interactions at sea between globalized industrial and local small-scale fishers in Ghana from 1984 to 2013 to examine the conditions under which resource users conflict or cooperate, linking them to broader political and economic dynamics across scales. We consider the institutional factors that mediate these interactions, identifying policies to promote cooperative, and avert conflictual incidents. We further consider the long-term effects of these patterns of conflict and cooperation for the resilience or vulnerability of the resource base, the fishers, and the institutions governing the system. We suggest that specific governance arrangements that reduce disparities between groups, promote bridging social capital, and enhance hybrid and cross-scale institutions offer the best potential to govern resource systems where traditional CPRs and market-oriented industries converge

Multiple Antibiotic Resistance-Coliform Bacteria in Some Selected Fish Farms of the Central Region of Ghana

This 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. The 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