Ministry for natural resources and the environment directorate general for environment

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2.9 Coastal, marine and oceanic biodiversity

The country’s coastal area is about 260km long and its exclusive economic zone is quite large. The coastal regions and the marine environment are an integrated resource and an essential component of the environment, offering invaluable possibilities to sustainable development in S. Tomé and Príncipe. Despite the interrelationship of both parts in the system, a separate analysis of same allowed for greater insight into the current state of things.

Negative impact on coastal and marine biodiversity is due to: Presence of solid and liquid chemical waste; increased water temperature; coastal erosion and estuary erosion, caused by increases in population density. There are several examples of negative impact. Fishing nets with extremely tight meshes (illegal) are being used on the territorial waters of S. Tomé and Príncipe, causing veritable ecological disasters. These nets capture growing specimens, such as the black sea bream (Pomadasys rogeri) of the family Haemulidae, which Santomeans have taken to calling “disaster”. Young fish of the species measure from 2 to 5cm in length, while adult fish grow to a length of 20 to 25cm, weighing 400-800g. The young weigh under 30g.

Where coastal fishing is concerned, there are 5 zones, as shown on a table, below. Throughout these zones, the concentration of fish is highly important:

  • North of Neves: a zone with large and small pelagic species;

  • The region of Micoló and Ribeira Afonso: small coastal pelagic;

  • South of São Tomé, between Porto Alegre and Ribeira Afonso: demersal and coastal pelagic;

  • Around Príncipe Island: demersal, large pelagic, and a zone with great potential for small pelagic species (sardines), not yet exploited;

  • Beyond 25 nautic miles: large pelagic.

Fig. 3: Map of main coastal fishing areas on the island of São Tomé.1

Fig. 4: Map of main coastal fishing areas on the island of Príncipe.1

2.9.1 Coastal biodiversity - Flora

Coastal flora is not very diverse and is mainly comprised of typical species in preferential habitats: There are species living in narrow sand bands, like Ipomoea pes capre, or Canavalia rosea; Others prefer transitional areas, as is the case with typical mangrove species. Savannas display significant change where coastal flora is concerned. Flora here is relatively homogeneous when compared with altitude flora that has not been subject to much anthropic pressure, as seen in S. Miguel, on the south of São Tomé, and Barriga Branca on the south of Príncipe island.1
On the beaches, dynamic vegetation presents dominant pioneering plants like Ipomoea pes capre and Canavalia rosea. These plants form a thick mat that favors settlement by some brush vegetation like Dalbergia ecastaphyllum, Conocarpus erectus, Baphia nitida and Hibiscus tiliaceus. These pioneering species, fixating on sand, bring about coastal bands that will later be colonized by arboreal and arborescent formations. Dominant in these formations are plants of the family Arecaceae such as the Cocus nucifera (coconut tree, an introduced species) and others such as Combretaceae, and Terminalia catappa.
Coastal regions have been subject to human impact from the early days of human settlement. The main introduced species were able to occupy a range of favorable habitats, competing with native species, impoverishing endemism on the islands. This might account for the scarce number of endemic species in coastal regions (sand banks and savanna).

Currently, human pressure on plant resources is translated into the felling of coconut trees and others for the extraction of building materials, fuel and coal; also, into accelerated urban development on account of the tourist industry and other economic development plans in the country.

Relativamente as Ilhas Tinhosas, Ilhéu Boné de Jóquei, e outros adjacentes ao Arquipélago, {fragment in the original; meaningless - the translator}

2.9.2 Coastal biodiversity - fauna

Coastal ecosystems in S. Tomé and Príncipe are comprised fundamentally of beaches, rocky coastlines, estuaries and marshland, where different species abound. Where this ecosystem is concerned, there is no research that particularly highlights fauna. Thus the data on certain species are, in practice, insufficient.

Along coastal areas, the fauna is made up mostly of birds inhabiting small islets and coastal areas away from human settlements. Main species are presented in a diagram below, where critically endangered species are included; species like sea turtles and reptiles that spawn on the coast, the endemic bat Tartarides thomensis, present in the savannas of the Praia das Conchas and the Lagoa Azul, on the north coast of S. Tomé and Príncipe. There are likewise threatened endemic species of insects such as Lepidoptera, Graphium leonidas thomasius e oelides bocagii (ENPAB-Forest Ecosystems, 2002). Other species of butterflies (not endangered) are Charaches, Dixeia piscicollis, Neptis eltringhami.

2.9.3 Transitional coastal areas

Here, 5 species of sea turtle occur frequently, coming to spawn on the coast. These are: Lepidochelys olivacea (Tatô), Chelonias mydas (Ambó), Eretmochelys imbricata (Sada) and Dermochelys coriacea (Ambulância), and finally, the carreta-carreta (ECOFAC). Spawning takes place from October to February, with greater frequency during November, December and January.

In S. Tomé and Príncipe, sea turtle eggs and meat are highly appreciated and an important source of animal protein, for which reason these animals are captured by the population.

Considering their conservation status, all five are endangered (E) (ENPAB-Marine and coastal ecosystems, 2002).

Besides the turtles, there are migratory birds such as the white-tailed tropicbird, Phaeton lepturus and Sula leucogaster, the brown booby. These can be observed on the Tinhosa and Sete Pedras islets.

The north coast of S. Tomé also provides habitats for endemic reptiles.

Additionally, the savanna on Praia das Conchas and Lagoa Azul presents an endemic bat, the Tartarides thomensis. This winged mammal belongs to the order Chiroptera.

Scheme 5: Main species that constitute coastal fauna on S. Tomé and Príncipe
Humans have long exploited this ecosystem. Turtles are regularly sought out for meat and eggs, which are highly valued by traditional Santomean cuisine; no less importantly they're a source of animal protein. Sand banks have been exploited for sand. Last but not least, farmers have burnt down wooded areas for agricultural purposes, and there have been spontaneous fires during the dry season.

The STP ACP 019, by ECOFAC, has undertaken significant protection measures and engaged in awareness campaigns on sea turtles, but this came to an end in 1999. Fishing communities, who appeared to have become aware of the need to preserve these turtles, still capture them. However, they benefit from legal endangered status according to ENPAB-Marine and Coastal Ecosystems 2002.

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