Marine Sciences

Contamination of aquatic environment is increasing and has been associated with indiscriminate discharge of solid wastes and effluents generated from industrial, domestic and agricultural activities. These wastes and effluents contain harmful substances, such as metals, which constitute a major problem on the quality of the Nigerian coastal water. This study evaluated the impacts of heavy metals on the water and sediment quality of Ologe and Badagry Lagoons, South-West Nigeria. The heavy metals (Cr, Cd, Cu, Zn, Pb and Fe) in water and sediments was analyzed with atomic absorption spectrophotometer (AAS) using standard protocols. The pollution index (PI) indicated that Cd and Pb had significant effects on the water quality of Ologe and Badagry Lagoons. The metal indices (MI) with Cd, Pb and Zn exceeded the threshold level of (MI > 1). The enrichment factor (EF) indicated extremely contamination with Cd and Pb; significantly contamination with Cr and Cu and very highly contaminatio...

The Lagos lagoon, Nigeria receives lots of organic wastes from anthropogenic sources. The biodegradation of these wastes by aerobic microbes has resulted in the depletion of the dissolved oxygen. Study of this area of the lagoon was conducted for two years to investigate the impact of hypoxia on the distribution, abundance and diversity of benthic macroinvertebrates. Water and benthic samples were collected monthly along the study stretch and analysed in a standard laboratory. Temporal variation in water physico-chemistry was largely controlled by rainfall pattern while the spatial variation was influenced by proximity to the Harbour as well as the pollution sources and types. A total of 3,159 individuals comprising three phyla, five classes, nineteen families and twenty three species were recorded. Iddo I, Iddo II, Ogudu and Agboiyi monitoring stations recorded very low individuals, but, relatively high number of polychaetes. Benthic macroinvertebrate community was dominated by the molluscs. Margalef’s index of species richness ranged from 0.79 to 2.57 while Shannon-Wiener index ranged from 0.40 to 2.19. Species evenness index ranged from 0.29 to 0.80. There was generally low biodiversity indicating the stressed nature of the study area.

A study of the morphological and physiological respiratory adaptations to hypoxia of three nereid polychaete species from Roscoff, France coast axis of the English Channel was conducted. Result of the analysis of their notopodia showed that Nereis diversicolor had the greatest specific branchial surface area (SBSA) followed by Platynereis dumerilii while Perinereis cultrifera had the least. The affinity of their purified haemoglobins to oxygen, interpreted by the values of their P 50 , also followed the same pattern. The results of this study show that Nereis diversicolor, which lives in muddy sediment is better adapted to hypoxia than Platynereis dumerilii which lives in tubes under rocks and Perinereis cultrifera which lives in sandy sediments under rocks.

The west of the Lagos lagoon, Nigeria has been subjected to lots of stress resulting from various anthropogenic activities around it. The sedentary nature of the benthic macrofauna makes them a very useful tool for assessing the health of this water body. Ecological study of these benthic organisms was conducted between January, 2007 and December, 2008 with the aim of using them to assess the pollution status of this part of the lagoon. Water and benthic samples were collected monthly and analysed in a standard laboratory. Results of the analysis of the physico-chemical parameters of water samples indicated that their temporal variation was controlled by the rainfall pattern while their spatial variation was controlled by proximity to sea and pollution sources. A total of 3,159 individuals comprising three phyla, five classes, nineteen families and twenty-three species were recorded. More individuals were recorded in the dry than in wet season. Iddo I, Iddo II, Ogudu and Agboiyi recorded very low individuals, but relatively high number of opportunistic species like the polychaetes. There was generally low biodiversity which indicates the stressed nature of the study area.

Food and feeding habits of 187 fish specimens made up of 17 species from Qua Iboe River estuary were studied from July – October 2008. Specimens with food were more (141; 75.40%) than those without food (46; 24.60%). Highest condition factor was obtained in Chrysichthys nigrodigitatus (2.71) while the least was found in Sarotherodon barracuda (0.37). Gastrosomatic index showed highest (100%) in eight species whereas the lowest occurred only in Trachinotus teraia (4.35%). The highest relative frequency of food items was observed in fish and sediments (10; 15.63%) while the lowest occurred in annelids, molluscs and unidentified foods (1; 1.56%). Others were crustaceans and detritus (8; 12.50%), algae and plant materials (7; 10.94%), nematodes (5; 7.80%) and protozoans and insects (3; 4.69%). Variation in food richness ranged from 1 food item (0.54%) in three species (Bathygobius soporator, Epinephelus aeneus and T. teraia) to 36 food items (19.67%) observed in Liza falcipinnis. In vie...

Food and feeding habits of 187 fish specimens made up of 17 species from Qua Iboe River estuary were studied from July – October 2008. Specimens with food were more (141; 75.40%) than those without food (46; 24.60%). Highest condition factor was obtained in Chrysichthys nigrodigitatus (2.71) while the least was found in Sarotherodon barracuda (0.37). Gastrosomatic index showed highest (100%) in eight species whereas the lowest occurred only in Trachinotus teraia (4.35%). The highest relative frequency of food items was observed in fish and sediments (10; 15.63%) while the lowest occurred in annelids, molluscs and unidentified foods (1; 1.56%). Others were crustaceans and detritus (8; 12.50%), algae and plant materials (7; 10.94%), nematodes (5; 7.80%) and protozoans and insects (3; 4.69%). Variation in food richness ranged from 1 food item (0.54%) in three species (Bathygobius soporator, Epinephelus aeneus and T. teraia) to 36 food items (19.67%) observed in Liza falcipinnis. In vie...

Water contamination is a serious global issue that affects a country's economy, human health, and aquatic life, potentially compromising people's livelihoods who rely on fishing. Contamination can occur due to various factors such as industrial wastes, domestic sewage, seawater, eutrophication, and in many countries as a result of oil extraction, refineries, storage leaks, and shipping to international destinations. Oil contamination is one of the worst-case scenarios due to the numerous consequences. Nigeria's Niger River Delta Basin is home to many oil refineries, as the country is Africa's largest oil producer. As a result, the river is highly contaminated, and its water is unfit for human or animal consumption and is unsuitable for irrigation. Cleaning up the river and keeping contamination levels under strict control is essential. This study provides a novel methodology for water control and identifying the most polluted areas, allowing authorities to identify the refineries that pollute the most. Amnesty International (https://www.amnesty.org/en/latest/news/2020/06/no-clean-up-no-justice-shell-oil-pollution-in-the-niger-delta/. Accessed 5 Mar 2022, 2020) has been very aggressive on this issue in this area and the identification of contaminating oil companies by Ratcliffe (This place used to be green: the brutal impact of oil in the Niger Delta- Guardian. https://www.theguardian.com/global-development/2019/dec/06/this-place-used-to-be-green-the-brutal-impact-of-oil-in-the-niger-delta. Accessed 5 Mar 2022, 2019).

This paper reports an in-vivo account of the impact of thermal stress on the biomass and size-distribution of estuarine populations of Pachymelania aurita in Epe Lagoon, Nigeria. Off all physicochemical variables investigated only water temperature was statistically different among study stations. A total of 7626 individuals of the organism comprising 2,371juveniles, 3586 immature adults and 2,034of spawning adults were collected from the study area. Highest populations of juveniles and immature adults occurred in station 3 where the highest water temperature occurred while, station 1 recorded lowest populations of the two size classes. Spawning adults occurred in highest number in station 2 while their lowest population was observed in station 3.Of the total biomass of 2491 g recorded, juvenile population recorded a total biomass of 143.401 g, immature adults contributed 874.424 g while spawning adults recorded 1473.19 g. Highest juvenile biomass (34.7 g) occurred in station 5 while, the least (17.7 g), was recorded in station 1. Station 3 accommodated the highest biomass (233.60 g) of immature adults and the least biomass for this group was observed in station 1.Biomass of the spawning adults was highest (475.08 g) in station 2 and the lowest biomass (162.03 g) for this class was observed in station 3. The elevated water temperature observed in station 3 affected the growth of the organism such that only few individuals developed to spawning adult. It is therefore important that, the regulatory agencies should carry out regular monitoring of cooling water discharge from Egbin Power Station to ensure compliance with stipulated laws. © JASEM https://dx.doi.org/10.4314/jasem.v21i5.1