International Journal of Marine Science 2016, Vol.6, No.27, 1-22
2
in calcifying organisms such as crustaceans and molluscs (Vezina and Hoegh-Guldberg, 2008; Barnard and Grekin,
2010), ripple effects in the ecosystem (Hall-Spencer et al., 2008), food chains and webs (Turley and Gattuso,
2012), to socioeconomic impacts on the livelihoods that depend on these fisheries (Hilmi et al., 2012).
Ghana has a vibrant marine fisheries industry which is likely to be impacted by global climate change and ocean
acidification. The Ghanaian fisheries sector plays an important role in national socioeconomic development
objectives relating to food security, employment, Gross Domestic Product (GDP) and foreign exchange earnings.
The dependence on fish and fishery products for livelihood and poverty reduction in Ghana cannot be taken for
granted (Asiedu and Nunoo, 2013). It is estimated that about 10% of the population depend directly or indirectly
on fish resource, which translate to 2.6 million people of the current population of 26 million. Ghana, located in
West Africa, has a coastline of about 550 km (Tamakloe, 2009), and a very narrow and shallow continental shelf.
The marine fishing industry consists of three main sub-sectors, namely, small scale (for artisanal or canoe),
semi-industrial (for inshore) and industrial sub-sectors. The marine artisanal fisheries are characterized by the use
of several gears that are operated from dugout canoes which is carved out of a single log of wood species called
‘wawa’
Triplochiton scleroxylon
and ‘onyina’
Ceiba petandra
. Gears such as beach serine, purse seine (APWs),
gill net, and lobster net are deployed by the artisanal fishermen. There are more than 12,700 canoes operating in
315 landing beaches and 190 fishing villages producing between 75 to 80% of the total marine fish landed
(Akyempon et al., 2014). The over three hundred locally made wooden vessels of the semi-industrial sector use
in-board engines, operate from eight main landing sites along the coast and fish with either purse seine or trawl
gears in coastal waters all year round.
On African coasts, few studies have been conducted pertaining to ocean acidification despite their biological
and socioeconomic vulnerability to future global changes (Lam et al., 2012; Dupont and Portner, 2013). An
improved understanding of how the biophysical impacts of ocean acidification would influence fish catche s
and fish protein supply and other economic activities generated by the world’s fisheries is therefore needed,
especially in Ghana, where dependence on the fishing industry is very high. Assessments of ocean
acidification impacts are also important for predicting future climate change and marine ecosystem responses
(Bates et al., 2012).
The primary objective of this study was to determine possible impacts of ocean acidification on the
abundance and diversity of fin- and shellfish species in coastal waters of Ghana. The study has three specific
objectives viz.: determine the extent and magnitude of impacts of ocean acidification on abundance and
diversity of fish stocks through monitoring of physico-chemical parameters of the ocean; determine the
abundance and species composition of landings of semi-industrial (trawlers) and artisanal (beach seine)
fisheries and key species susceptible to ocean acidification; and determine species biomass and composition
of ichthyoplankton in coastal waters susceptible to ocean acidification. This paper presents the findings of
the first year out of on-going four years of primary and secondary data collection to determine the impacts of
ocean acidification on fish biodiversity in Ghanaian coastal waters.
2 Materials and Method
2.1 Study design
A two-level sampling strategy was adopted for data collection. The first was a geographical stratification, which
thus selected two geographical sites. The first site was the Teshie Sangonaa fish landing beach, located in Teshie,
to represent the artisanal fishery, while the second site was the Tema Inshore fish landing beach in Tema, to
represent the semi-industrial fishery. The second level of stratification was on seasonal basis, where data was
collected in the lean and peak seasons. The lean fishing season usually runs from December/January to
February/March while the peak fishing season usually runs from June/July to September/November (MOFI,
2008).
2.2 Study sites
The Teshie Sangonaa landing beach is located within the Teshie Township, a suburb in the Greater-Accra Region
of Ghana (Figure 1). The beach is located at Latitude 05
o
35.004”N, Longitude 000
o
05.362”W and serves the
