Comparative Study of the Mangrove Ecosystems of Douala-Edea Reserve (Cameroon) and Songor Ramsar Site (Ghana) Using Parameters of Ecological Value
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Date
2014-06
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University of Ghana
Abstract
In most tropical countries including Ghana and Cameroon, knowledge of ecological
importance of mangrove ecosystem in terms of litter production, structural characteristics, water
and soil properties, has been qualitatively well documented and recognised. However, there is
scanty quantitative scientific data to back this up. The purpose of this research dissertation was to
study and compare the mangrove ecosystems of Cameroon and Ghana two contrasting coastal
zones, using parameters of ecological value and to have a better understanding of their
interrelationships within mangrove ecosystem as well as the impact of their values or roles to the
global ecosystem (marine and coastal) within the West and Central African ecoregion.
The study was conducted within the period of two years for both countries (One year in
each country), Two major sites were chosen in Ghana (Songor Ramsar site) and Cameroon
(Douala Edea Reserve). In each site, three mangrove stands: 1) Avicennia, 2) Rhizophora and
mixed (Rhizophora and Avicennia) were selected and marked out, and parameters like litterfall,
structural characteristics, water and soil properties were assessed.
This research on mangrove ecosystem addressed four objectives: (1) assessment of the
structural parameters; (2) assessmentof litter production; (3) determination of physicochemical
and climatic
factors affecting mangrove structure
and productivity;
(4)
Show the
interrelationships between mangrove resources in both countries.
The results in both countries showed that, (1) Leaves, twigs, flowers and fruits were
present in litter samples all over the study period with highest peak mainly in the dry season, and
leaf production accounted for more than 80% in each country; (2) High values of most of the
major nutrients (N, P, K, Mg, Ca) investigated and used in evaluation of mangrove ecosystem
importance were recorded between March and October for Cameroon mangroves and in
December for Ghana mangroves.
(3) The mean highest species density was observed in Rhizophora for Cameroon and
Avicennia and mixed in Ghana. The mangrove of Cameroon showed greater heights than their
Ghanaian counterparts. (4) The values of Physical parameters (DO, BOD, EC, TDS, TSS), and
nutrients were most often high in Cameroon, compared to Ghana. Mangrove waters were also
found more alkaline in Cameroon than in Ghana. (5) It was observed that in both countries,
Avicennia had the highest percentage of silt. In addition to that nitrogen ,phosphorus, leaves
(Litterfall), nitrate, Biochemical Oxygen Demand, pH, Phosphate, salinity, Conductivity
(Mangrove Water ), percentage organic nitrogen, electrical conductivity, acidity, Exchangeable
magnesium, ECEC Effective Cation Exchange Capacity, and
available phosphorus Av P
(Mangrove Soil), height, basal area and density (Structural characteristics) were the major
discriminatory ecological features of the mangroves of Ghana and Cameroon. Correlations with
litterfall, structural, water and soil variables indicated that mangrove ecosystem within and
across the countries respond differently to environmental conditions.
The combination of rainfall, temperature and salinity was a good predictor of variability in
the production of litterfall in both countries.
This study contributes to a better understanding of how mangrove ecosystems function.
Additional work in other geographic areas within the West and Central African ecoregion is
needed to provide a broader perspective on the ecological importance of mangrove ecosystem
and their impact on the nearby marine and coastal areas.
Description
Thesis (PhD) - University of Ghana, 2014