International Journal of Marine Science 2016, Vol.6, No.27, 1-22
1
Research Article Open Access
Preliminary Studies on Impacts of Ocean Acidification on Diversity of Fish
Species Landed by Artisanal and Semi-Industrial Fisheries in Ghana
F. K. E. Nuno
Edna E. K. Quansah, P. K. Ofori-Danson
Department of Marine & Fisheries Sciences, University of Ghana, P. O. Box LG 99, Legon. Accra. Ghana. West Africa
Corresponding author email
International Journal of Marine Science
2016, Vol.6, No.27 doi
Received: 12 Jun., 2016
Accepted: 16 Aug., 2016
Published: 16 Aug., 2016
This is an open access article published under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and
reproduction in any medium, provided the original work is properly cited.
Preferred citation for this article
:
Nunoo F. K. E., Quansah E. E. K., and Ofori-Danson P. K., 2016, Preliminary Studies on Impacts of Ocean Acidification on Diversity of Fish Species Landed
By Artisanal and Semi-Industrial Fisheries in Ghana, International Journal of Marine Science, 6(27): 1-22 (
doi
Abstract
Increased absorbance of carbon dioxide from the atmosphere has led to the changing of the chemistry of the oceans. In
addition to already existing stressors, the resultant ocean acidification poses multiple threats to marine species biodiversity; and
goods, services and livelihoods that depend on them. This study set out to determine possible impacts of globally occurring ocean
acidification on the abundance and diversity of fin- and shellfish species and ichthyoplankton in the artisanal and semi-industrial
fisheries of Ghana. Physico-chemical parameters of the sites where fishing by artisanal and semi-industrial vessels were carried out
were collected in the lean and peak fishing seasons. Fish samples were collected, species identified, counted and diversity indices
calculated for each fishery and fishing season. A Canonical Correspondence Analysis (CCA) was used to identify which of the
principal factors influenced the fish species. Four ocean acidification parameters (pH, carbonate ion concentration, total alkalinity,
Revelle factor) out of six principal components were identified to contribute significantly (RELATE, r = 0.955, P < 0.05) to
biological variations observed in the two fisheries. A decreasing trend in ocean acidification indicators was observed for both
fisheries and variations observed in species abundance between seasons and fisheries, which provide evidence of the possible
occurrence of ocean acidification in Ghanaian waters and likelihood of impacts on fish diversity. Continuous long term monitoring of
the studied parameters and inclusion of adaptive and mitigative strategies for impacts of ocean acidification in marine fisheries
management plans is recommended.
Keywords
Ocean Acidification; Impacts;
Fish Biodiversity; Fisheries; Ghana
1 Introduction
In response to recent global increase in carbon dioxide emissions primarily from anthropogenic causes (IPCC,
2001), the oceans are absorbing large amounts of carbon dioxide (CO
2
) from the atmosphere. According to Fabry
et al. (2008), the oceans have absorbed about 30% of carbon dioxide emitted into the atmosphere as a result of
anthropogenic activities such as land use change, fossil fuel burning and cement production. The increased
absorbance of carbon dioxide from the atmosphere has led to the changing of the chemistry of the oceans (Fabry
et al., 2008; Cooley and Doney, 2009; Kroeker et al., 2010; Armstrong et al., 2012, Turley and Gattuso, 2012),
resulting in a parallel increase of hydrogen ion concentration and a consequent increase in acidity (Armstrong et
al., 2012); through reduction in seawater pH and saturation states for calcium carbonate minerals such as aragonite
and calcite.
Ocean acidification is generally considered one of the multiple stressors affecting the oceans ecosystems (IPCC,
2011). In addition to already existing stressors of the oceans such as over fishing and pollution, ocean acidification
would pose multiple threats to marine species, biodiversity and the goods and services the oceans provide (IPCC,
2011; Rogers and Laffoley, 2011). Several authors such as Fabry et al. (2008); Sumaila et al. (2011) and
Mohammed and Uraguchi (2013) have projected ocean acidification to have varying consequences and impacts on
the marine ecosystem at large and fisheries in particular. Perry (2010) anticipates that developing countries,
tropical nations and the poor would be at the worst receiving end of these varying impacts.
The impacts of ocean acidification on the marine ecosystem are multiple; ranging from affecting the physiology of
fish species (Dupont and Portner, 2013; Portner et al., 2004; Fabry et al., 2008) to reduction of calcification rates
