The Western and Central Africa Land–Sea Interface: A Vulnerable, Threatened, and Important Coastal Zone Within a Changing Environment - The Land/Ocean Interactions in the Coastal Zone of West and Central Africa - page 2

ecosystem services and benefits within estuaries, coastal, and marine areas in West and
Central Africa, with six main objectives: (1) Introducing the framework of current studies,
including factors related to oceanographic, geologic, geomorphologic, physicochemical and
biogeochemical components of these ecosystems; (2) Emphasizing the need to study natural
and human-induced impacts on the functioning and sustainability of estuaries and other
coastal systems, with possible options for managing them for sustainable use; (3) Facilitating
recognition by coastal scientists and managers of the unique features of estuaries and other
relevant coastal environments in Africa, while also enhancing existing knowledge regarding
the associated ecosystem services; (4) Encouraging young researchers, scientists, and
advanced students to undertake holistic, integrated studies on estuaries and coastal areas in
their regions, using an ecosystems assessment approach and ecosystem-based management;
and (5) Providing professionals, students, and the general public with readily accessible and
understandable scientific articles and papers on the economic and ecological importance of
estuaries and other related coastal ecosystems in Africa.

Keywords

Ecosystem goods and services Estuaries and coastal ecosystems West and Central Africa

Ecosystem approach Oceanographic Geologic Geomorphologic Physicochemical

Biogeochemical Socioeconomic factors

Introduction

The ecological importance of the Western and Central
African coastal region and the adjacent uplands areas (from
the continental margins to the offshore island nations),
which contain a wide and varied range of important habitats
and associated biota that exhibit a high biological diversity,
cannot be overemphasized. The continental shelf along the
coast is in general narrow, with widths between 20 and
50 km (but reaching up to 150 km in certain places like
offshore Guinea-Bissau, Sierra Leone, and Ghana). One of
the main characteristics of this African marine and coastal
region is the occurrence of seasonal upwelling, which
explains the abundance of substantial commercial stocks of
demersal and pelagic fish in its coastal waters (World Bank
Africa 1994 ). Indeed, the economy of most of the countries
discussed in this report is highly dependent on their coasts
and their marine environment.

The West and Central African coastline extends over
around 6,000 km, from the shores of the sandy desert of
Mauritania in the north to the lagoon areas and coastal belts
of the Gulf of Guinea, including deeply cut coastlines of
islands (for example, Guinea-Bissau and the Bissagos
islands) and estuaries up to the Republic of Congo (Fig. 1 ).
The immense Niger and Cross River delta and Congo River
mouth are located at the eastern and southern end. The West
African ''ecomarine'' region (more or less corresponding to
the Canary Current Large Marine Ecosystem 1 ) stretches
along 3,500 km of coastline and covers six countries:
Mauritania, Senegal, Gambia, Cape Verde, Guinea-Bissau,
and Guinea (Diop 1990 ). The coastline exhibits a great
variety of habitats, ranging from enormous extensions of
seaweed prairies in the north, to rocky cliffs and long sandy
beaches, to mangroves and well-developed estuaries in the
south (UNEP-WCMC 2007 ). Beyond this ecoregion, the
entire Guinea Current Large Marine Ecosystem is located to
the south of Guinea, stretching as far as Nigeria, and well
beyond Gabon, offshore of the two Congo's, Sao Tomé and
Principe, and Equatorial Guinea (see chapter
'' Morphological and Hydrodynamic Changes in the Lower
Estuary of the Senegal River: Effects on the Environment of
the Breach of the 'Langue de Barbarie' Sand Spit in 2003 ' ').

Natural Conditions and Processes

Regional Morphology and River Basin Drainages

Four narrow coastal sedimentary basins, containing a few
volcanic intrusions and other rocky outcrops at the major
capes, have developed on the edges of the coastline,
including the Senegalese-Mauritanian basin, the Cote
d'Ivoire basin, the Niger basin (including Niger Delta), and
the coastal basins from Gabon to Congo (UNEP 1999 ).
All four coastal sedimentary environments are strongly
influenced by their river basin drainages. There are five major

1

Large Marine Ecosystems encompass waters from river basins and
estuaries to the seaward boundaries of continental shelves and margins
of coastal currents and water masses (Sherman 1994 ).