West African Journal of Applied Ecology

Assessing the food habits of Crassostrea tulipa (L. 1819) in a commercial fishery of a Ramsar site in Ghana

2023-12-13T12:44:26+00:00

The development of wild commercial oyster culture in Ghana is of recent concern. Reduction in feed cost through reliance on natural feed sources is an important sustainable aquaculture management strategy. In many parts of sub-Saharan African countries including Ghana, there is limited documented information on the natural food items fed on by Crassostrea tulipa (Lamarck, 1819). The oyster in the Densu estuary was studied for food habits using the Numerical, Frequency of Occurrence, and Index of Relative Importance (IRI) methods and condition index for a duration of 18 months. The diet of the oyster was dominated by golden algae (Phylum Ochrophyta; IRI=595), red algae (Phylum Rhodophyta; IRI=209), green algae (Phylum Chlorophyta; IRI=131.37) and diatoms (Phylum Bacillariophyta; IRI =172). There was a high species diversity (D = 6.60 ± 0.10 - 7.01 ± 0.03; H '= 0.30 ± 0.12 - 0.32 ± 0.05) among the food items ingested by C. tulipa. Golden algae was the most abundant (IRI= 56%), followed by red algae (IRI = 16%) and the diatoms (IRI = 13%). The less abundant phyla were Chlorophyta (IRI= 8 %), Cynophyta (IRI = 6 %) and Arthropoda (IRI = 1 %). The oyster was in a good state of wellbeing (Mean Condition index = 139.50 ± 0.11) and feeds on a wide range of plankton species. This information is essential in the development of natural feed for the oyster industry in Densu estuary. The presence of green algae in the diet requires further investigation to help minimize the possible toxic effects it may have on the fishery and humans.

Evaluating the Effect of Land use Land Cover Changes on Land Suitability for Crop Production Using Remote Sensing and GIS

2024-02-16T16:59:31+00:00

The impact of Land Use Land Cover Changes (LULCC) on agricultural land from 1986 to 2016 was examined using Remote Sensing (RS) and Geographic Information System (GIS) in Kwara State, Nigeria. The aim of the study was to show how a GIS tool could be incorporated into a Multi Criteria Analysis (MCA) and an Analytical Hierarchy Process (AHP) model to assess the suitability of land. Under several conditions which define suitable land for arable cropping, the structural design of an integrated GIS-MCA-AHP was anticipated to correspond with the decision maker's preferences. Additionally, the integration was anticipated to quantify the extent of land cover modifications and assess how removal of vegetation would affect the soil. As a major factor in the analysis, the Normalized Differential Vegetation Index (NDVI) was employed with GIS and Remote Sensing (RS) technologies, and as secondary, MCA and AHP models. In Arc-Map (GIS) 10.3.1, the RS data imagery from 2016 was used and recognized by NDVI satellite images. The images were categorized according to RS data, field study data, and geographical factors. The variables were soil texture, depth, pH, organic carbon, rainfall, temperature, slope, elevation, and land use land cover. To examine the extent of land use and land cover changes in relation to soil types and land suitability, the MCA-AHP model employed a weighted sum overlay. The results showed that farming accounted for 46% of all land use, and that LULCC was primarily to blame for the loss of arable land and environmental degradation. The proportion of the total land area used for farming (farmland), the built up area, bare land, and water bodies increased from 34 to 46, 15 to 30.4, 5 to 10, and 3 to 4%, respectively. Forest land, on the other hand, saw a drop from 43 to 9.6%. While 11.40% of the total land area was highly suitable for arable cultivation, 19.30% was moderately suitable, 30.40% was marginally suitable, 23.12% was currently unsuitable, and 15.78% was permanently unsuitable. The study shows that the AHP model was useful for calculating land use weights that were comparable to those calculated using other techniques. The model was helpful in making planning decisions for land use, and thus could be useful in managing sustainable agriculture. It was concluded that in addition to the fast rate of deforestation, increasing anthropogenic activities were degrading arable land at the study site.

Effects of Pearl millet (Pennisetum glaucum) forage cropping pattern on biomass yield and in vitro NDF digestibility

2023-12-13T16:25:01+00:00

The study was conducted to evaluate four Pearl millet forage cropping pattern within the Guinea Savannah Agro-ecological zone of Ghana. Four cropping patterns (sole grass as control, grass cultivated on the borders of Pigeon pea crop, Grass cultivated as intercrop with Pigeon pea and Grass cultivated as spot in Pigeon pea) in RCBD were imposed on pearl millet forage. Agronomic data which included plant height, number of tillers, and total biomass yield was taken in both the initial establishment and regrowth. The biomass was separated into leaf, stem, and whole botanical fractions for chemical composition and in vitro NDF digestibility analysis. Cropping patterns significantly (p< 0.05) influenced all agronomic parameters except for plant height at first cut. The grass in spot cropping pattern had the highest plant height (1.48 m) at the first harvest. Meanwhile, intercropping in the second harvest produced the highest (23) number of tillers whilst spot planting in the third harvest gave the least number of tillers (8). Sole grass (control) produced the highest (1352.6 kg DM/ ha) biomass yield in the second harvest whereas spot planting gave the lowest biomass (45.6 kg DM/ha) in the third harvest. A total biomass yield of 2,755.3 kg DM/ha/annum, 1,695.7 kg DM/ ha/annum, 1,199.5 kg DM/ ha/annum and 594.2 kg DM/ ha/annum were produced for sole grass, border, intercrop, and spot respectively. In the first cut, the two-way interaction effect of cropping pattern and botanical fraction significantly (p<0.05) affected all chemical parameters except DM. The highest NDF and ADF were reported in the Whole fraction of the Spot cropping pattern and stem fraction respectively. Botanical fraction significantly (p<0.05) influenced digestibility parameters with the leaf fraction of spot planting recording the highest IVDMTD (870.4 g/kg DM) and NDFD (773.9g/kgDM) and the highest ME obtained in the leaf fraction of sole grass. The two-way interaction effect of cropping pattern and botanical fraction significantly (p<0.05) influenced all chemical parameters and ME with the highest NDF and ME recorded in the stem and leaf fractions of sole grass in the second cut. In the third cut however, botanical fraction significantly influenced all chemical parameters except DM and the two-way interaction effect of cropping pattern and botanical fraction affected all digestibility parameters analysed. The study concluded that pearl millet forage can be introduced as a border crop in a crop/livestock farming system in the savannah agro-ecological zone of Ghana.

Food and Feeding Habits of the Big-eye Grunt, Brachydeuterus auritus (Valenciennes, 1831) in the Coastal Waters off Tema, Ghana

2023-12-13T16:36:25+00:00

Examination of 424 stomach contents of Big-eye grunt, Brachydeuterus auritus from May and September to December 2016 showed four major food groups. By a decreasing order of abundance, these are: crustacea (64%), fish (35%), molluscs (0.4%) and insects (0.3%). Anchovies were the commonest prey types, with a frequency of occurrence of 53.6%, followed, among the crustaceans, by lobster larvae (34.5%) and shrimp larvae (5.3%). Crab zoe larvae and crab shell had very low frequencies (<1.0% each). Molluscs, represented by squid and juvenile cuttlefish, and insects, represented mainly by chironomid larvae, both had very low frequencies (<1.0). A low feeding intensity was recorded in October and November, a period coinciding with the highest number of fish with empty stomachs. Conversely, a greater feeding activity was recorded in May, September and December, a period coinciding with the highest number of fish with ¼, ½, ¾ and full stomachs. The proportion of crustaceans in stomach contents increased significantly with increasing size
of B. auritus, while the proportion of fish significantly decreased with age of fish. It is recommended that stomach content analysis of this fish species be replicated to cover all seasons and other geographical areas.

Gold Mining Effects on Water Quality in Domenase and Nkotumso along River Offin, Upper Denkyira West District

2023-12-13T16:54:58+00:00

Artisanal gold mining (ASM) has been an important source of primary livelihood activity for poor populations in Ghana. The sector now functions as a vital social safety-net and in some cases, provides the only source of income in employment-constrained economies and helping copious poor households survive during increasingly uncertain times. However, artisanal mining is linked to the release of heavy metals into the mainstream environment causing water pollution. In this study, heavy metals namely mercury (Hg), arsenic (As), manganese (Mn), lead (Pb) and iron, (Fe) were quantitatively analysed using PinAAcle 900T Perkin Elmer Atomic Absorption Spectrophotometer. The samples were taken from the core water source area of Domenase and Nkontomisa on the Offin River in the Upper Denkyira West District of the Central region of Ghana. The decreasing trend of metals was observed in water as Hg > Pb > As > Mn >Fe, whiles the average distribution of these heavy metals in water was 0.11, 0.02, 0.02, 0.122, 0.184 mg/L respectively for Nkotumso. In Domenase, the decreasing trend of metals was observed in water as Pb > Hg > As > Fe >Mn, and their averages were 0.028, 0.09, 0.018, 0,188, 0.090 mg/L, respectively. The concentration of Hg, As, and Pb in the water samples were above the WHO (2011) permissible limits except Mn and Fe which were below the guideline limit. The pH range of 6.24-6.53 was noted for Nkotumso and 5.24-5.83 (strongly to moderately acidic) for Domenase. The pH of water samples collected from Nkotumso was within WHO (2011) guideline values whereas the values of Domenase were not. The results indicate that the water is not suitable for drinking and other domestic purpose such as cooking since heavy metals such as Hg, As, and Pb which are known to be carcinogenic were high. The study recommends that continuous monitoring of Hg, As and Pb in the water and other aquatic biota of Nkotumso and Domenase along the River Offin should be assessed to ensure the safety of the ecology in the vicinity of the river.

Growth and Yield Performance of Maize Hybrids on the Vertic soils of Accra Plains Ghana

2023-12-13T17:12:18+00:00

Maize is the most important food staple in Ghana however yield potential of 6t/ha for this cereal has yet to be realized. Increasing yield productivity has become crucial in recent times due to food security pressures as a result a growing population and a rapidly expanding use in the local industry. Maize hybrids offer the opportunity to significantly increase yields in the country and this has led to an increasingly greater number of hybrids being developed and released. There is therefore the need to test maize hybrids before recommending them to farmers under specific agroecological areas. In this study, a recently released hybrid ‘Legon Aburo’ (released by West African Centre for Crop Improvement - WACCI), tested alongside two commonly used hybrids ‘Opeaburo’ (local hybrid) and ‘Pan 53’ (imported hybrid) and two Open Pollinated Varieties (OPVs) (‘Obatanpa’ and ‘Abontem’), in the coastal savannah agro- cological zone with distinctive vertic black heavy clayey soils. The results show significant differences (p < 0.05) in the leaf area index (LAI) among the maize varieties and was highest in ‘Obantanpa’ in both seasons. Biomass which varied significantly among varieties was highest in ‘Legon Aburo’ and ‘Pan 53’ and lowest in ‘Abontem’. In terms of yields the most popular OPV ‘Obatanpa’ was comparable to the local hybrid ‘Opeaburo’ and the foreign hybrid ‘PAN 53’. The OPV ‘Abontem’ had the lowest grain yield whiles the WACCI hybrid ‘Legon Aburo’ produced the highest grain (<7t/ha) for both years. This novel hybrid variety may offer an opportunity for farmers in the Coastal Savannah with predominantly vertic clayey soils to increase their yields.

Does Crocodile Conservation Matter in Sacred Natural Sites of Benin (Western Africa)?

2023-12-13T17:24:05+00:00

Crocodiles are protected species present in Sacred Natural Sites (SNS) in Benin.The impact of SNSs on the conservation of crocodylians in Benin were carried out by (i) assessing the extent to which anthropogenic activities affect crocodylians' population, and (ii) analysing the impact of social and religious changes for the conservation of crocodylians over a timescale. The characteristics of the crocodile population and habitats in 11 SNSs during daytime and night were also provided. Semi-structured interviews with 330 respondents were conducted and land use/land cover changes with 2000 and 2020 remote sensing data were analysed. The West Africa crocodile (Crocodylus suchus) was recorded in 81.8% SNS and consisted of 61.5% hatchlings, 15.6% juveniles, 11.85% subadults, and 11.1% adults (N= 135 crocodiles). With increasing degradation of natural ecosystems and increasing settlements/agricultural lands, there has been a significant decrease in crocodile abundance and extirpation (18.2% SNSs). Communities perceived crocodiles as sacred, a link with ancestors, the god of fertility, and a way to preserve water. Nevertheless, respondents also perceived the negative impact of introduced religions (70.9%) and no longer worshiped sacred crocodiles (52.7%) due to religious prohibition. Raising awareness, and participatory management of SNSs with the communities would help to mitigate the threats.