African Journal of
Environmental Science and Technology

  • Abbreviation: Afr. J. Environ. Sci. Technol.
  • Language: English
  • ISSN: 1996-0786
  • DOI: 10.5897/AJEST
  • Start Year: 2007
  • Published Articles: 1014

Full Length Research Paper

Short-term response of flat tree oyster, Isognomon alatus to CO2 acidified seawater in laboratory and field experiments

Lailah Gifty Akita
  • Lailah Gifty Akita
  • Department of Marine and Fisheries Sciences, University of Ghana, P. O. Box LG 99, Legon-Accra, Ghana.
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Andreas Andersson
  • Andreas Andersson
  • GRD Scripps Institution of Oceanography UC San Diego 9500 Gilman La Jolla, CA 92093-0244, United States of America.
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Houssem Smeti
  • Houssem Smeti
  • Mediterranean Institute of Oceanography, Marseille, France.
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Tiago Queiroz
  • Tiago Queiroz
  • Department of Geophysics, University Agostinho Neto, Angola.
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  •  Received: 01 August 2020
  •  Accepted: 04 January 2021
  •  Published: 31 January 2021

Abstract

Seawater changing chemistry has consequences on coastal ecosystems and their living resources. Future projections suggest the pH could drop ~0.2-0.3 pH units by the year 2100 under a business-as-usual (BAU) CO2 emission scenario. Marine calcifying organisms such as corals, calcifying algae, crustaceans, mussels, oysters and clams are most likely to be impacted by ocean acidification. The Isognomon alatus (flat tree oyster) is an important species that can be negatively affected by the lowering of seawater pH. Isognomon alatus is an important food source, a substrate for other benthic organisms (e.g., stone crab, Menippe mercenaria) and contribute to nutrients recycling in coastal ecosystems. The study was conducted to test the impacts acidified seawater CO2 on the growth of I. alatus under controlled laboratory conditions as well as field experiment. The Isognomon alatus lost weight and experienced negative growth rates of –0.56 ± 0.36 mg g-1day-1 under average pH values of 7.8 expected by the end of this century compared to a loss of –0.26 ± 0.23 mg g-1day-1 under ambient pH (value 8.1) conditions. In contrast, I. alatus incubated in a field experiment showed a gain in weight and positive growth of 3.30 ± 0.23 mg g-1day-1 despite exposure to pH levels (~7.4) during low tide significantly lower than those experienced in the laboratory. Overall, the results showed concern on the impacts of acidification flat tree oyster (Bivalvia:Isognomonidae). A decline of calcifying bivalves populations can impact coastal ecosystems function and indirectly affect the human beings that depend on them as a food source. 

 

Key words: Ocean acidification, climate change, Isognomonidae, shell dissolution, bivalve's growth, estuarine.