Comparative productivity and biomass yields of the Guinea Current LME

Wiafe, George; Dovlo, Emmanuel K; Agyekum, Kwame Adu

doi:10.1016/j.envdev.2015.07.001

Cited by 7 publications

(5 citation statements)

References 23 publications

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“…SSLs form and persist under stable conditions allowing stratification (thermocline, pycnocline, halocline), i.e., in the absence of turbulence, caused by intense upwelling [83,84]. Our observations are also consistent with those of other studies highlighting trends, for environmental parameters, such as SST [31,85], and in some fishes and plankton populations [31,38,72]. In the mid-trophic compartment, the northern and southern CCLME were therefore impacted in the same way over the study period.…”

Section: Annual Variability and Trends In Atlantic African Large Mari...supporting

confidence: 90%

“…Species composition can largely change over season and years linked to environmental parameters. Therefore, we speculate that the differences we observed among LMEs are likely due to physical and biogeochemical characteristics of the pelagic habitat [72].…”

Section: Comparative Analysis Of Sound-scattering-layer Variables Wit...mentioning

confidence: 84%

“…In our results, GCLME function was close to the southern CCLME one. GCLME plankton was very sensitive to upwelling presence [72]. The upwelling regime of southern CCLME and GCLME lead micronekton populations in the same direction in both LMEs.…”

Section: Comparative Analysis Of Sound-scattering-layer Variables Wit...mentioning

confidence: 91%

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Applying Acoustic Scattering Layer Descriptors to Depict Mid-Trophic Pelagic Organisation: The Case of Atlantic African Large Marine Ecosystems Continental Shelf

Mouget

Brehmer

Perrot

et al. 2022

Fishes

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To identify key nonspecific organisational characteristics of the mid-trophic pelagic communities, which remain a challenge, we work with sound scattering layers (SSLs). Application was tested in the three African Atlantic Large Marine Ecosystems (AALMEs) to assess the utility of adapting and developing new acoustic variables. Our methodology allowed comparison between Large Marine Ecosystems (LMEs) based on 14 morphological, spatial and acoustic variables to characterize SSLs over time. These original variables were effective in monitoring and comparing the LMEs, and even allowed us to discriminate different organisations inside the Canary Current LME. Common traits identified for all AALMEs included the importance of the shallowest SSL. However, we identified an unexpected night-time pattern in SSL distributions in the Benguela Current LME which reflect a major difference in diel vertical migration mechanisms relative to other AALMEs. We also highlighted the predominance of elementary sampling unit (ESUs) with a single SSL and an unoccupied tiny layer close to the bottom, even if some ESUs presented up to six SSLs. Inter-annual changes in SSL organisation are highlighted by adaptation of original variables as the proportion of the water column occupied by SSLs and the relative importance of the shallowest SSL. SSL variables have been used mostly in deep water; here, we applied them on the continental shelf. SSL variables can be used to standardize the monitoring of marine ecosystems and capture change in spatial structure and function of mid-trophic pelagic marine ecosystems worldwide, even in data-poor areas where species identification of lower-trophic pelagic organism remains a challenge.

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Section: Annual Variability and Trends In Atlantic African Large Mari...supporting

confidence: 90%

Section: Comparative Analysis Of Sound-scattering-layer Variables Wit...mentioning

confidence: 84%

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Applying Acoustic Scattering Layer Descriptors to Depict Mid-Trophic Pelagic Organisation: The Case of Atlantic African Large Marine Ecosystems Continental Shelf

Mouget

Brehmer

Perrot

et al. 2022

Fishes

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“…proportions in tunas collected after the upwelling period started (~ August) between 0° and 10°E. This change is consistent with the 20:5n-3-rich diatoms development favored by cool upwelling waters (20-25 °C) in the eastern Gulf of Guinea (Wiafe et al 2016). FA might thus be an efficient tool to monitor forage taxa of tuna across seasons and years.…”

Section: Trophic Position Of Yellowfin Decreases In the Atlantic Oceansupporting

confidence: 76%

Seasonal habitat and length influence on the trophic niche of co-occurring tropical tunas in the eastern Atlantic Ocean

Sardenne

Diaha

Amandé

et al. 2019

Can. J. Fish. Aquat. Sci.

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In the Gulf of Guinea, bigeye tuna (Thunnus obesus; BET) and yellowfin tuna (Thunnus albacares; YFT) are an important part of commercial fisheries and play a prominent ecological role as top predators. Using fatty acid profiles and carbon and nitrogen stable isotopes, we examined their trophic niche partitioning in this understudied region. Trophic niche overlap was high (>70%), similar to percentages in other ocean basins. BET occupied a higher trophic position than YFT and fed on deeper prey (high δ15N values and high proportions of monounsaturated fatty acids). The trophic position of YFT decreased slightly in the last 15 years (δ15N values decreased by ∼0.5‰), suggesting a change in epipelagic communities, as observed in the eastern Pacific Ocean. Ontogenic changes were limited to BET. For both species, the dietary proportion of the diatom marker 20:5(n-3) increased in the seasonal upwelling area, highlighting the influence of seasonal habitat on the diet of tuna. The relatively lipid-rich muscle (∼6% dry mass) of Atlantic tropical tuna suggests a richer diet in this region than that of Indian Ocean tropical tuna and (or) differences in energy allocation strategies.

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“…With regard to marine microbiology and production, conditions on Ghana's shelf are similar to those prevailing on other shelf areas of West Africa. These conditions include warm sea surface temperatures of 24-29 • C, two major hydrographic seasons (upwelling from July to September and thermal stratification from October to March) and significant input of organic matter and nutrients via rivers and overland runoffs (Giresse & Cahet, 1997;Wiafe et al 2016). It has therefore been suggested that Ghana's shelf is a representative reflection of other areas for growing C. tulipa in West Africa (Chuku et al, 2023).…”

Section: Microalgae Isolation and Culturementioning

confidence: 99%

Isolation and evaluation of local microalgal isolates as feed for larval rearing of Crassostrea tulipa towards optimisation of mangrove oyster seed production in Ghana

Krampah,

Mensah,

Acheampong

et al. 2024

Aquaculture Fish & Fisheries

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This study explored the potential of three local microalgal isolates as feed for oyster larvae in laboratory‐rearing experiments, towards the optimisation of seed production of Crassostrea tulipa to support its large‐scale farming along the West African coast. Three species of local microalgae—Rhodomonas sp., Nannochloropsis sp. and Pseudanabaena sp.—were isolated from waters off the coast of Ghana, West Africa, following a serial dilution technique. The growth performance of the isolates was assessed in the laboratory through daily estimation of cell density until the stationary phase was observed. Characterisation of the microalgal isolates was carried out by estimation of their biovolume, carbon content and energy content. Biovolumes of the microalgae were calculated from the estimated equivalent spherical diameters using proposed geometric shapes and formulae. Carbon weight and carbon energy content were subsequently calculated using derived conversions. The three microalgal isolates showed potential for large‐scale cultivation in the laboratory with marked differences in daily increases in cell densities. Nannochloropsis sp. and Rhodomonas sp. recorded the highest and the lowest peak densities of 2.4 × 105 and 1.5 × 105 cell mL−1, respectively, from an initial inoculating cell density of 1.05 × 105 cell mL−1. The estimated mean biovolumes of Rhodomonas sp., Nannochloropsis sp. and Pseudanabaena sp. were 238.9, 8.182 and 42.42 µm3, respectively, and the corresponding derived carbon energy contents were 1.7 × 10−6, 7.13 × 10−8 and 1.05 × 10−7 J, respectively. Results from a laboratory rearing experiment indicated that the individual microalgal isolates supported the growth and survival of oyster larvae at different scales, but a mixed diet of the three promoted superior growth and survival of C. tulipa larvae. The three local microalgal isolates‐ Rhodomonas sp., Nannochloropsis sp., and Pseudanabaena sp.‐ were well adapted to laboratory culture conditions, and the observed differences in growth and survival of the oyster larvae fed on these algal diets could be due to the differences in diet properties and biochemical compositions of the different species. A combination of the three algal diets, however, provided complementaery nutrients for the optimal growth and survival of C. tulipa larvae. The outcome of this study shows that local microalgal isolates have the potential to support hatchery rearing of C. tulipa, which is essential for the development of commercial mangrove oyster aquaculture in West Africa.

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Comparative productivity and biomass yields of the Guinea Current LME

Cited by 7 publications

References 23 publications

Applying Acoustic Scattering Layer Descriptors to Depict Mid-Trophic Pelagic Organisation: The Case of Atlantic African Large Marine Ecosystems Continental Shelf

Applying Acoustic Scattering Layer Descriptors to Depict Mid-Trophic Pelagic Organisation: The Case of Atlantic African Large Marine Ecosystems Continental Shelf

Seasonal habitat and length influence on the trophic niche of co-occurring tropical tunas in the eastern Atlantic Ocean

Isolation and evaluation of local microalgal isolates as feed for larval rearing of Crassostrea tulipa towards optimisation of mangrove oyster seed production in Ghana

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