1 Biodiversity

Shailla Fall

A bird carcass amongst saline-heavy land (Senegal).
Photo by: Milo Mitchell, 2013

Marine and Coastal Biodiversity in Senegal

Senegal, the westernmost country in Africa, includes over 700 km of coastline just South of the Sahara desert. Hence, it represents the northern limit of distribution for a large number of coastal and marine animals and plants. It also constitutes critical resting and wintering areas for several palaearctic migrant birds. Major coastal habitats include:

  1. Floodplain depressions and salt flats in the deltas of the three major rivers (the Senegal, the Saloum and the Casamance) that flow into the Atlantic Ocean. These depressions host important wintering waterfowl and waders (most notably the Avocet), serve as nesting sites for pelican and flamingo, and function as nurseries or spawning ground for coastal species, including shrimp, mullet (7 species) and Fimbriated herring (Ethmalosa fimbriata).
  2. The Niayes, a series of small depressions located amongst the coastal sand dunes found North of Dakar, which hold a high plant biodiversity.
  3. Large expanses of mangrove forests found at the mouth of the Saloum and Casamance rivers (over 1,800 km²). Small patches of mangrove subsist at the mouth of the Senegal River and on the edges of coastal lagoons south of Dakar, such as the Somone. The mangrove host severely threatened populations of the West African Manatee (Trichechus senegalensis), the African hump-backed dolphin (Sousa teuszii), crocodiles, and even hippopotami in Casamance. They also contain huge tidal mudflats where large concentrations of waders feed off an abundance of invertebrates and shellfish. They are a critical wintering site for palaearctic ospreys (Pandion haliaetus). Finally, the mangroves play a critical role in the life cycle of several commercially important coastal fish species.
  4. Sandy beaches, where five species of sea turtles are known to nest: Olive Ridley (Lepidochelys olivacea), Green (Chelonia mydas), Loggerhead (Caretta caretta), Leatherback (Dermochelys coriacea) and Hawksbill Turtle (Eretmochelys imbricata). Small islands and sandbars strewn along the coast also hold large nesting colonies of pelicans, gulls and terns.
  5. The Cap Vert volcanic outcrop that stands out along the otherwise sandy coastline. The rocky shores have a distinct fish fauna, with some coral patches off the Island of Gorée. Offshore islands also harbor a colony of Red-bellied tropic birds (Phaeton aethereus), the only one along the coast of West Africa.

The Government of Senegal has created a string of protected areas to preserve coastal biodiversity. These include: the Djoudj National Park, the Ndiaël Nature Reserve, the Gueumbeul Nature Reserve, the Langue de Barbarie National Park, the Îles de la Madeleine National Park, the Popenguine Nature Reserve, the Saloum Delta National Park, the Kalissaye Bird Reserve, and the Basse Casamance National Park. Three of these areas are Ramsar sites (Djoudj, Ndiaël and Saloum). Moreover, the Saloum is also a Biosphere Reserve.

Source: Global Environment Facility Marine and Coastal Biodiversity in Senegal 

 

I) Explain the following terms

  1. Coastal habitats
  2. Floodplain depressions
  3. Salt flats
  4. Niayes
  5. Mangrove
  6. Biosphere reserve

II) Answer the following questions

  1. What are the characteristics of coastal habitats?
  2. What are the different plants that can be found in the Niayes of Dakar?
  3. What are the characteristics of the Niayes?
  4. The rocky shores have a distinct fish fauna, with some coral patches off the Island of Gorée. What are coral patches?
  5. Some islands such as the Pacific Islands have coral reefs. How are coral reefs forms?
  6. Rhizophora and Avicennia are trees that grow in the mangroves of the coastal lagoons of Somone. Explain how these trees have adapted to live in salt water.
  7. Sea turtles are found mostly on sandy beaches. The green turtle is very much appreciated by fisherman. Why has there been a decline in the number of these turtles?
  8. What type of cultivation has developed in the Niayes found on the outskirts of Dakar?
  9. What is the purpose of creating protected areas?

III) Complete the table below

Protected areas Species to be protected
Djoudj National Park
Îles de la Madeleine National Park,
the Saloum Delta National Park
the Basse Casamance National Park
the Popenguine Nature Reserve
the Djoudj National Park
the Langue de Barbarie National Park

IV) Say whether the following steatements are true or false. If false make them true.

  1. Sea turtles need rocky shores for nesting
  2. Palaeartic birds live in northern Africa.
  3. The West African Manatee are found in the delta of the Casamance.
  4. There are coral patches around mangroves.
  5. Hippopotami can be found in mangroves.

Read the following extract.

Despite the Government’s effort, Senegal’s marine and coastal biodiversity is under severe pressure, both within and outside of protected areas. The most immediate threat is habitat destruction. Senegal’s coast hosts more than half of the country’s population within only 1/6 of its area. Population migration is motivated by the geography of economic opportunities, and is aggravated by large-scale land degradation in the hinterland. This trend is likely to continue in the foreseeable future. The coast also attracts over 90% of tourists visiting Senegal. As a result, relatively untouched natural habitats along the coast are being settled. The marshlands in and around the Cap Vert have been filled or contaminated. Industrial pollution and untreated waste have transformed the Baie de Hann into an ecological wasteland and created a major human health hazard. Agriculture is impinging on floodplain wetlands and mangrove forests, destroying spawning grounds and fish nurseries. Large-scale tourism has greatly reduced available habitat, most notably the availability of nesting grounds for sea turtles.The migration of populations and economic activities towards the coast has also led to a harsher exploitation of coastal and marine resources. Tree cover, an important source of fuelwood, is rapidly decreasing. In specific areas, mangrove trees are been used to smoke fish, in the absence of other means of conservation. Ironically, increased commercialization of smoked mangrove oysters has, in certain localities, led to both the disappearance of the oysters and of the trees on which the oysters grow, leaving behind unproductive flats. The international market for shark fins is decimating shark stocks. Bird colonies are subjected to collecting of eggs. Manatees and sea turtles are hunted down. The establishment of large fish landing points in the Saloum delta, such as Missirah and Djifère in the Saloum, is also putting considerable pressure on local fish and shellfish stocks. More generally, the catch by commercial fishermen tends to exceed annual growth for most species (including tuna, groupers and Sardinella sp.), and as a result breeding stocks are being compromised.

Source: USAID (2008) Senegal Biodiversity and Tropical Forests Assesstment http://pdf.usaid.gov/pdf_docs/PNADL464.pdf

 

I) Answer the questions below.

  1. How are the marine and coastal biodiversity under the threat of habitat destruction?
  2. What are the economic opportunities that exist on Senegal’s coast?
  3. What is the consequence of the contamination of the marshlands on biodiversity?
  4. Explain how using mangroves and wetlands can impact on biodiversity.
  5. Why is tourism considered as a threat to the flora and fauna?
  6. What is the relationship between breeding stocks and fish landing points in Missirah and Djifere?

II) Write a paragraph explaining the measures that can be taken to protect the biodiversity in the affected areas.

 

III) Why do you think it is important to protect the palaeartic migrant birds? Why are these birds called migrant birds?

 

IV) People are using mangrove trees to smoke fish. Eggs are being collected for food. Manatees and turtles are being hunted. What do you think can be done to prevent the destruction of mangroves, bird colonies and the disappearance of turtles?

 

EDC

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