Stands of mangrove are the appropriate and, sometimes, only habitat for a range of resident and migratory birds, fish, reptiles, mammals, mollusks, and crustaceans (12). Besides the famous mollusks and crustaceans (black conchs and shrimp), the sanctuary protects a great variety of commercially important fish, more than 200 species of birds (including many rare or endangered species), and rare and threatened mammals, including the Crab-eating raccoon (Procyon cancrivorus) and the neotropical otter (Lutra longicaudis) (13).
The mangroves in the sanctuary are the southernmost occurrence of the mangroves in the Pacific coast of South America. The semi-arid climate and the dynamic and fragile character of the ecosystem make the area a high conservation priority (14).
Flora
Mangroves fall into one of three evergreen tree families: Rhizophoraceae, Verbenaceae and Combretaceae. There are five species of mangrove: two species known as red mangrove (Rhizophora mangle and Rhizophora harrisonii), black mangrove (Avicennia germinans), white mangrove (Laguncularia racemosa), and the button mangrove (Conocarpus erectus). Each is adapted to thrive in a highly saline and flood-prone environment that is equally terrestrial and marine (15).
Mangrove thickets in Tumbes are formed by a collection of over 40 species of plants, most notably the Red mangrove (Rhizophora mangle). Mangroves prosper in warm, equatorial waters between the Tropics of Cancer and Capricorn and mangroves inhabit the brackish area where the saltwater of the ocean and the freshwater of the river mix. This area experiences significant tidal action and receives substantial sediment from the river. Mangroves reproduce from seeds - single pods that break open when they fall from the tree or as floating pods that drift until they land on dry land - or through vegetative means - through stringy branches that take root when they touch sediment. This adaptation makes distinguishing roots from trunks nearly impossible. A vast network of canals and estuaries connects the complex systems of mangrove thickets. This network serves to transport the flow of saltwater from the ocean during high tide and the flow of freshwater during low tide (16).
Vegetation at the margins of the estuaries is characterized by tidal flux and the morphology of the Tumbes and Zarumilla Rivers. Mangroves at the extreme margins are sparse and stunted, subject to more extreme tides and salinity. Equatorial dry forest dominates the central, dry portion of islands and the uplands surrounding the mangrove stands. On dry land, the vegetation is scrubland, typical of the vetch and grassy biotypes (17).
The scrublands surrounding the mangrove thickets include shrub species like Phitecellobium excelsum, Cordia lutea, Mimosa acantholoba, and Palo brea (Cercidium praecox). Tree species include Chorisia sp., Hualtaco (Loxopterigium huasango), Incense tree (Bursera graveolens), Cochlospermum sp., Kiawe (Prosopis pallida), Caesalpinia corymbosa, and Sapote (Capparis angulata). Seasonal herbaceous vegetation is represented by grassy species such as Antephora sp., Aristida adscencionis, Bouteloua aristoides, Stinkgrass (Eragrostis cilianensis), legumes such as Stylosanthes sp., Crotalaria sp., Tephrosia purpurea, and Tephrosia cinerea, and the genuses Cyperus and Scirpus. Other species in the scrubland include Saltgrass (Distichlis spicata), Brachiaria mutica, Antephora hermaphrodita, Crowfoot grass (Dactyloctenium aegyptium), Crowngrass (Paspalum racemosum), Ipomoea crassifolia, Cocabus postratus, and Bidens pilosa (18).
Fauna
Seven species of mammals inhabit the Manglares de Tumbes National Sanctuary. Important species for conservation include the rare Crab-eating raccoon (Procycon cancrivorus) and the Neotropical otter (Lutra langicaudis). There are eight species of reptiles, including the endangered Tumbes Crocodile (Crocodylus acutus) and sea turtles like the Green Turtle (Chelonia mydas) and the Olive Ridley Turtle (Lepidochelys olivacea). 120 species of birds are present in the coastal area, 57 of which require mature mangrove stands ten years or older. Eight species are found only in mangroves: Clipper rail (Rallus longirostris), Rufous-necked wood rail (Aramides axillaries), Mangrove Blackhawk (Buteogallus subtilis), Yellow-crowned night heron (Nyctanassa violaceus), Bare-throated night heron (Tigrisoma mexicanum), White ibis (Eudocimus albus), Yellow warbler (Dendroica petechia), and the Great-tailed grackle (Quiscalus mexicanus). More than thirty species of birds inhabit the scrublands surrounding the mangroves. The sanctuary is home to 93 species of fish, 33 species of gastropods, 34 species of crustaceans, and 24 species of bivalves.
This rich ecosystem possesses species with immense economic value, particularly the Black conch (Anadara tuberculosa), Anadara similis, Anadara grandis, Chione subrugosa, Penshell (Atrina maura), and Mytella guyanensis. Among the crustaceans, Ucides occidentalis is the most important. Also important are four species from the genus Penaeus, the White shrimp (P. vannamei), P. stylirostris, P. occidentalis, and Yellow-legged shrimp (P.californiensis), as well as the lobster Panulirus gracilis (19).
The Tumbes crocodile was highly persecuted for its skins, bringing it to the brink of extinction. One of only four neotropical crocodile species in existence, it is only occasionally found in the wild in remote portions of the Tumbes River (20). Equally rare is the Crab-eating raccoon. Conversations with a former park guard suggest that conch harvesters killed raccoons by destroying their habitat because they eat the conchs (21).
