Table 7. Result of experimental fishing at Domunli lagoon Family
Species TN
ASL cm AW g
Cichlidae Sarotherodon melanotheron
1 9.5 10.0
Mugilidae Mugil cephalus
4 15.6 16.5
Elopidae Elops lacerta.
2 7.9 12.5
Ostreidae Crassostrea tulipa
- -
500
TN = Total number; ASL=Average Standard Length; AW = Average Weight
The fish species consisted of both brackish-water S. melanotheron and typical estuarine species Mugil cephalus and Elops lacerta. However, indications from inhabitants of the area suggested
a dominance of tilapia species, fiddler crabs Uca tangerii and oyster. A very high average of 42 fiddler crab holes was counted per square metre at the exposed banks of the coconut lagoon. The
estuarine sesarmid crab Sesarma huzardi was also reported to occur in the area, but not in abundance.
3.3.4 Critical Features and Conservation Significance
The Domunli lagoon appears to be pristine and highly productive with a luxuriant stretch of mangroves. The inhabitants are aware of the ecological services of the mangroves, mainly for
supporting both the lagoonal and marine fisheries. However, there are no established traditional or conservation practices specifically to protect it. There are a few people who cut down the
mangroves for firewood; however, inhabitants claim that most of the firewood is obtained from the farm areas. There are no sacred groves, although some grave sites were observed near the
beach.
According to the community members, the mangroves have become more abundant over the past years and the stands seem to have moved closer to the community. They have observed no
significant changes in water quality, despite the periodic blooms of algae they refer to as “green green”. Over time, they have observed that the lagoon has become shallower and in the last five
years, clams that were once abundant have disappeared.
The mangrove vegetation and the relatively shallow nature of the lagoon support the life of shorebirds. It is envisaged that the eastern portions of the lagoon i.e., estuary mouth may be
impacted should the plan to site a gas station from the Jubilee Field materialize. Depending on the location of the pipe, inflows between the lagoon and adjacent marine environment may be
affected. There is therefore the need for a monitoring programme to be instituted in order to generate reliable data for sustainable management of the lagoon. Due to generally low fishing
pressure and a small fishing community, fish abundance is high although with low diversity. The habitats look promising for aquatic biodiversity if managed due to reduced human influence. As
such it is recommended for management purposes.
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3.4
Amansuri Main
The Amansuri Lagoon is located near Beyin in the Jomoro District Appendix 3. It is part of the Amansuri wetland 4º 55 N 20º 15 W which comprises of a network of freshwater and brackish
water lagoons. The Amansuri is the only known intact swamp peat forest in Ghana. The famous 500 years old Nzulezu village, where houses are built on stilts and traditional life adapts to the
watery conditions, is built on the Amansuri Lagoon Figure 5. The area has already been designated as an Important Bird Area based on Birdlife International criteria.
Figure 5. Amansuri wetland with Nzulezu village at the background 3.4.1 Water quality
An average pH value of 5.3 was recorded in the Amansuri Lagoon indicating moderate acidic conditions, possibly due to humic acids. The levels of Pb and As were below WHO limits.
However, mean levels of Cu, Hg, Cd, Zn and Fe exceeded WHO recommended limits for aquatic life, which poses a threat to aquatic life. The low DO concentration in this lagoon can have
adverse effects on fish and other organisms ANZECCARMCANZ, 2000, such as immune suppression which can cause elevated susceptibility to diseases for several years Mellergaard
and Nielson, 1987.
Toxicity of trace metals such as Zn and Cu could be potentially enhanced during low DO levels in the lagoon ANZECCARMCANZ, 2000. Therefore, the relatively high BOD recorded
should be a matter of concern. The mean phosphate concentration was within the recommended range, the mean nitrate concentration far exceeded the NOAAUSEPA recommended range,
resulting in an N:P ratio of 52:1. This exceeds the recommended N:P ratio of 10:1 for the support of high diversity NOAAUSEPA, 1988.
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The community depends on a borehole as their main source of potable water, although some members have access to pipe water or a well. The village of Amansuri could be the major source
of the organic load into the lagoon, as toilet facilities are mostly unavailable, contributing to the high BOD measured. Although there is a public dump for solid waste, community members
usually dispose of their liquid waste in the streets and in gutters. When interviewed, most of them believed that there were no negative environmental impacts of these activities, suggesting
the need for basic environmental education towards sanitation and protection of diversity.
3.4.2 Biodiversity
