OCEAN ACIDIFICATION: GEOLOGICAL EVIDENCE, PRESENT
CONDITIONS AND IMPLICATIONS ON KENYA’S COASTAL
ECOSYSTEM IN A CHANGING GLOBAL CLIMATE
ABSTRACT
The increasing global atmospheric CO2 attributed to anthropogenic activities such
as fossil fuel burning and land use changes has resulted to a decline in oceans pH
in a process known as ocean acidification. This is because oceans have been the
only long-term sink for this emitted CO2. This study looks at the past events of
ocean acidification: their causative factors and biotic responses. It presents the
recent CO2 emission trends since the pre-industrial times with evidence from
previous studies and examines at the potential impacts of ocean acidification to the
Kenya’s coastal ecosystem more so the coral reefs in a changing global climate.
The study entailed review of scientific papers and other relevant publications,
adoption and modification of graphics and consultations with several experts. It is
evident from this study that, natural causes such as volcanic eruptions were the
main triggers of past events of ocean acidification in the geological record. For
example the Siberian traps basalts eruption in the Permo-Triassic boundary (~248
Ma) which released ~43,000 PgC of CO2 into the atmosphere. This emission led to
carbonate dissolution in shelf settings and ocean anoxia. Recent trends of CO2
emissions from pre-industrial period show that the rise is unprecedented and man
is the sole cause of it. The study also found out that, Kenya’s reef ecosystem
suffers degradation from both natural and human induced stresses. Human pressure
on the reef results from destructive practices during extraction of reef resources for
example fishing using explosives. Natural processes affecting it include
sedimentation from inland rivers and the changing global climate. The latter for
instance, led to bleaching and mortality of over 50% corals during the El Nino
event of 1997/1998. Such previous blows on this reef system make it more
vulnerable to ocean acidification compared to other coastal areas with a similar but
more stable ecosystem. Consequently various species and communities dependent
on this reef will also be impacted. Thus, this study recommends that further
research on the sensitivity of this ecosystem to various environmental problems
should be done before policies on its conservation are made and that international
research collaborations should be considered too.