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Outbreaks of diseases, non-natural algal blooms and
infestations by pests have been assessed as symptoms of an
unhealthy marine ecosystem.
The results of research estimates indicate that a very high
percentage of the pollution currently discharged into the
coastal area is done by the local inhabitants. Untreated waste
on beaches and in the nearshore zone is directly related to
the health status of the local population. Epidemics such as
typhoid fever, cholera and similar outbreaks are the results
of poor sanitation or the symptoms of consuming raw or
partially cooked oysters, clams and mussels harvested from
coastal waters into which raw or inadequately treated sewage
had been discharged (Meith-Avcin and Helmer, 1978).
High concentrations of harmful nutrients and micro-
organisms areusually contained inuntreatedand inadequately
treated waste. Aquatic ‘over nourishment’ from nutrients may
lead to eutrophication of coastal receiving water bodies like
estuaries and bays bringing various negative consequences
such as plankton blooms, oxygen depletion and fish kills.
Such adverse circumstances are sometimes observed in the
streams, rivers, and estuaries but they go unrecorded.
7. Pests, introduced species,
diseases and algal blooms
The Sierra Leone marine environment is overall in good
condition with regards to pests, introduced species, algal
blooms and outbreaks of diseases that can disturb the
ecological balance of the aquatic realm.
However, the problem of coastal and marine invasive
species is likely to worsen over the coming decade due to
increases in shipping activities throughout the region. Ship
traffic is projected to continue growing into the coming
decade with economic growth and therefore the outlook
for transfer of alien organisms through ship‘s ballast water
could be expected to grow.
The Queen Elizabeth II quay is the primary international
gateway for all foreign vessels entering into the country.
There have not been documented any pest species from
this quay or any of the wharfs to have caused any significant
ecological impact in the local areas.There have been reports
of malaria and such outbreaks, especially in coastal areas of
high urbanisation and population densities, and these have
been attributable to poor sanitation where mosquitoes
have been able to proliferate in stagnant water settlements.
The high risk areas for such incidents to happen are in