**3.2 Vertebrates**

#### **3.2.1 Fishes**

A total of 438 species have been reported in the Orinoco delta, grouped in 20 orders and 82 families. The best represented groups are the orders Characiformes, Perciformes, and Siluriformes with 132, 99 and 87 species respectively (Table 3). The five families with the highest species richness are the Characidae (73 species), Cichlidae (24 species), Pimelodidae (24 species), Sciaenidae (23 species), and Loricariidae (17 species) (Lasso et al., 2009; Lasso & Sánchez-Duarte, 2011). Of these identified species, 39 % are marine and estuarine, while 61% are strictly from freshwater habitats.


Table 3. Number of fish families, genera, and species reported for the Orinoco Delta.

The ichthyological richness of the delta is third largest within the Orinoquia region, with the internal delta of the Ventuari-Orinoco (Venezuela) and the Estrella Fluvial de Inírida (Colombia) having the highest fish diversity (Lasso et al., 2010a). For the entire Orinoquia region, a total of 993 fish species (including freshwater and estuarine species) have been reported. These are grouped in 19 orders, 74 families, and 422 genera (Lasso et al., 2004c). For ichthyofauna, the Orinoco Delta is one of the best known regions of Venezuela compared to other remote and more continental areas of the Orinoco Basin that support a more complex fish fauna from a taxonomical point of view. Studies on fish span several

A total of 438 species have been reported in the Orinoco delta, grouped in 20 orders and 82 families. The best represented groups are the orders Characiformes, Perciformes, and Siluriformes with 132, 99 and 87 species respectively (Table 3). The five families with the highest species richness are the Characidae (73 species), Cichlidae (24 species), Pimelodidae (24 species), Sciaenidae (23 species), and Loricariidae (17 species) (Lasso et al., 2009; Lasso & Sánchez-Duarte, 2011). Of these identified species, 39 % are marine and estuarine, while 61%

**Orders Families Genera Species Number % Number % Number %**  Carchariniformes 2 2 2 0.7 2 0.5 Pristiformes 1 1 1 0.4 2 0.5 Myliobatiformes 7 9 10 3.6 15 3.4 Elopiformes 2 2 2 0.7 2 0.5 Anguilliformes 2 2 3 1.1 3 0.7 Clupeiformes 3 4 11 3.9 24 5.5 Characiformes 13 16 73 26.0 132 30.1 Siluriformes 11 13 62 22.1 87 19.9 Gymnotiformes 5 6 20 7.1 34 7.8 Batrachoidiformes 1 1 1 0.4 1 0.2 Lophiiformes 1 1 1 0.4 1 0.2 Atheriniformes 1 1 1 0.4 1 0.2 Cyprinodontiformes 3 4 7 2.5 12 2.7 Beloniformes 2 2 5 1.8 6 1.4 Syngnathiformes 1 1 1 0.4 1 0.2 Synbranchiformes 1 1 1 0.4 1 0.2 Scorpaeniformes 2 2 2 0.7 2 0.5 Perciformes 19 23 68 24.2 99 22.6 Pleuronectiformes 3 4 6 2.1 8 1.8 Tetraodontiformes 2 2 4 1.4 5 1.1 **Total 82 100 281 100 438 100** 

Table 3. Number of fish families, genera, and species reported for the Orinoco Delta.

The ichthyological richness of the delta is third largest within the Orinoquia region, with the internal delta of the Ventuari-Orinoco (Venezuela) and the Estrella Fluvial de Inírida (Colombia) having the highest fish diversity (Lasso et al., 2010a). For the entire Orinoquia region, a total of 993 fish species (including freshwater and estuarine species) have been reported. These are grouped in 19 orders, 74 families, and 422 genera (Lasso et al., 2004c). For ichthyofauna, the Orinoco Delta is one of the best known regions of Venezuela compared to other remote and more continental areas of the Orinoco Basin that support a more complex fish fauna from a taxonomical point of view. Studies on fish span several

**3.2 Vertebrates 3.2.1 Fishes** 

are strictly from freshwater habitats.


Table 4. Summary of the main publications by theme related to the Orinoco Delta, the Gulf of Paria, and the Venezuelan Atlantic Front.

Biodiversity and Conservation of the Estuarine

**or Class Class or Order Order or Family** 

**Phylum** 

**Kingdom** 

and Marine Ecosystems of the Venezuelan Orinoco Delta 79

Animalia Chordata Amphibia Anura 3 6 1 Aves Accipitriformes 1 2 1 Aves Anseriformes 2 2 1 Aves Apodiformes 2 11 1 Aves Caprimulgiformes 2 4 1 Aves Charadriiformes 5 36 2 Aves Ciconiiformes 4 21 1 Aves Columbiformes 1 7 1 Aves Coraciiformes 1 3 1 Aves Cuculiformes 1 7 1 Aves Falconiformes 3 18 1 Aves Galbuliformes 1 3 1 Aves Galliformes 1 1 1 Aves Gruiformes 2 7 1 Aves Passeriformes 15 94 4 Aves Pelecaniformes 4 7 1 Aves Phoenicopteriformes 1 1 1 Aves Piciformes 2 9 1 Aves Procellariformes 3 8 1 Aves Psittaciformes 1 8 1 Aves Strigiformes 1 4 1 Aves Trogoniformes 1 2 1 Reptilia Crocodilia 2 4 4 Reptilia Squamata 6 12 4 Reptilia Testudines 8 14 4 Mammalia Carnivora 1 2 2 Mammalia Cetacea 4 13 3 Mammalia Sirenia 1 1 4

**TOTAL 79 307** 

**4. Threats to marine biodiversity** 

Table 5. Number of vertebrate (amphibians, birds, reptiles, and mammals) species and families reported in the Orinoco Delta region. State of knowledge classified as in Table 1.

Any plan to achieve effective conservation of biodiversity and the functionality of the natural systems requires precise knowledge of the sources of actual or potential hazards or pressures and where and how those pressures could affect ecosystems and their components. Such pressures (pollution, resource exploitation, etc.) cause environmental disturbances in a given area, impacting the biological attributes of the biota or physical components of the ecosystem. Threats to biodiversity can then be described as a pressure source, by its spatial coverage, and the intensity of its actual or potential impacts. The Orinoco Delta and the Venezuelan Atlantic Front are very diverse collections of particular marine and coastal ecosystems (mangrove and palm forests, sand barriers, estuary and micro watershed nets, muddy/sandy marine bottoms, demersal fish and crustacean

**Described families** 

**Described species** 

**State of knowledge** 

areas: biology, ecology, fisheries, biogeography, taxonomy, and biodiversity, among others (Table 4). The freshwater fish fauna of the Orinoco Delta results from the combination of the ancestral biota of the Guayanas with the more recent savannah ("*llanera*") biota. On the other hand, the estuarine and marine ichthyofauna found from the Gulf of Paria and the South of Trinidad down to the Amazon river is very uniform (Cervigón, 1985). Toward the northern Venezuelan coast, this situation changes drastically. All the species that are characteristic of the estuarine zone of the delta almost disappear, with the exception of a few euryhaline species that inhabit either positive or negative estuaries, and other species that are mainly marine as adults, but their larvae and juveniles frequent brackish waters. In the Maracaibo lake, another large estuarine system located in the western Caribbean coast of Venezuela, these same estuarine species that had not been reported along more than 2,000 km of coast are present again, showing an important affinity in the fish fauna of the Maracaibo Lake and the Orinoco Delta. According to Cervigón (1985), this ichthyofaunal affinity in Venezuelan territory seems to extend to the Atlantic coast of Colombia, particularly to the south of Cartagena including the Gulf of Urabá.

#### **3.2.2 Other vertebrates**

Several aquatic mammals are widely distributed in the Orinoco Delta area. Amphibians are represented by terrestrial and freshwater species associated with mangrove forests. Birds are highly diverse with 255 species, including 21 orders and 54 families. There is only one endemic species of birds in this area, the black-dotted piculet (*Picumnus nigropunctatus*) (Martin & Bone, 2007). The aquatic birds are grouped in eight orders with 36 species of Charadriiformes, including jacanas, lapwings, plovers, sandpipers, snipes, skimmer, and gull terns; 21 species of Ciconiiformes, like herons, egrets, bitterns, storks, and ibises; 8 species of Procellariformes or petrels; 7 species of Pelecaniformes, including pelicans, boobies, cormorants, darters, and frigatebirds; 7 species of Gruiformes, such as limpkins, wood-rails, crakes, and gallinules; 3 species of Coraciiformes or kingfishers; 2 species of Anseriformes such as screamers and ducks, and one species of Phoenicopteriformes or flamingos.

Delta reptiles are represented by three orders, Crocodilia, Squamata, and Testudines. The most representative species of Crocodilia are the spectacular cayman (*Caiman crocodilus*), and the crocodiles *Crocodylus acutus* and *Crocodylus intermedius*, which are on the IUCN Red List of threatened species under the category of vulnerable and critically endangered, respectively. Marine reptiles are represented by five species of sea turtles, all reported along the Venezuelan coast. The five species are considered to be endangered and are protected by the Venezuelan wildlife protection law (Ojasti, 2005; Guada, 2000; Rodríguez & Rojas-Suárez, 2008). Four of these species nest in the Gulf of Paria, from Irapa to Punta Narizona. The leatherback turtle (*Dermochelys coriacea),* spawns in the Barra Mariusa and Tobejuba area, within the boundaries of the Delta del Orinoco National Park and Reserva de Biosfera Delta del Orinoco. As for mammals, the most common is the freshwater dolphin, *Inia geoffrensis* (tonina), while other species, like the river dolphin, *Sotalia fluviatilis*, the manatee, *Trichechus manatus*, the giant otter, *Petronura brasilienis,* and the long-tailed otter, *Lontra longicaudis,* are rare. The giant otter and the manatee have been reported as critically endangered (Linares, 1998). Only two species of the 13 Cetacea recorded (*Megaptera novaeangliae* and *Balaenoptera physalus*) are considered as vulnerable in the Red List of Venezuelan fauna (Table 5).


areas: biology, ecology, fisheries, biogeography, taxonomy, and biodiversity, among others (Table 4). The freshwater fish fauna of the Orinoco Delta results from the combination of the ancestral biota of the Guayanas with the more recent savannah ("*llanera*") biota. On the other hand, the estuarine and marine ichthyofauna found from the Gulf of Paria and the South of Trinidad down to the Amazon river is very uniform (Cervigón, 1985). Toward the northern Venezuelan coast, this situation changes drastically. All the species that are characteristic of the estuarine zone of the delta almost disappear, with the exception of a few euryhaline species that inhabit either positive or negative estuaries, and other species that are mainly marine as adults, but their larvae and juveniles frequent brackish waters. In the Maracaibo lake, another large estuarine system located in the western Caribbean coast of Venezuela, these same estuarine species that had not been reported along more than 2,000 km of coast are present again, showing an important affinity in the fish fauna of the Maracaibo Lake and the Orinoco Delta. According to Cervigón (1985), this ichthyofaunal affinity in Venezuelan territory seems to extend to the Atlantic coast of Colombia,

Several aquatic mammals are widely distributed in the Orinoco Delta area. Amphibians are represented by terrestrial and freshwater species associated with mangrove forests. Birds are highly diverse with 255 species, including 21 orders and 54 families. There is only one endemic species of birds in this area, the black-dotted piculet (*Picumnus nigropunctatus*) (Martin & Bone, 2007). The aquatic birds are grouped in eight orders with 36 species of Charadriiformes, including jacanas, lapwings, plovers, sandpipers, snipes, skimmer, and gull terns; 21 species of Ciconiiformes, like herons, egrets, bitterns, storks, and ibises; 8 species of Procellariformes or petrels; 7 species of Pelecaniformes, including pelicans, boobies, cormorants, darters, and frigatebirds; 7 species of Gruiformes, such as limpkins, wood-rails, crakes, and gallinules; 3 species of Coraciiformes or kingfishers; 2 species of Anseriformes such as screamers and ducks, and one species of

Delta reptiles are represented by three orders, Crocodilia, Squamata, and Testudines. The most representative species of Crocodilia are the spectacular cayman (*Caiman crocodilus*), and the crocodiles *Crocodylus acutus* and *Crocodylus intermedius*, which are on the IUCN Red List of threatened species under the category of vulnerable and critically endangered, respectively. Marine reptiles are represented by five species of sea turtles, all reported along the Venezuelan coast. The five species are considered to be endangered and are protected by the Venezuelan wildlife protection law (Ojasti, 2005; Guada, 2000; Rodríguez & Rojas-Suárez, 2008). Four of these species nest in the Gulf of Paria, from Irapa to Punta Narizona. The leatherback turtle (*Dermochelys coriacea),* spawns in the Barra Mariusa and Tobejuba area, within the boundaries of the Delta del Orinoco National Park and Reserva de Biosfera Delta del Orinoco. As for mammals, the most common is the freshwater dolphin, *Inia geoffrensis* (tonina), while other species, like the river dolphin, *Sotalia fluviatilis*, the manatee, *Trichechus manatus*, the giant otter, *Petronura brasilienis,* and the long-tailed otter, *Lontra longicaudis,* are rare. The giant otter and the manatee have been reported as critically endangered (Linares, 1998). Only two species of the 13 Cetacea recorded (*Megaptera novaeangliae* and *Balaenoptera physalus*) are considered as vulnerable in the Red List of

particularly to the south of Cartagena including the Gulf of Urabá.

**3.2.2 Other vertebrates** 

Phoenicopteriformes or flamingos.

Venezuelan fauna (Table 5).

Table 5. Number of vertebrate (amphibians, birds, reptiles, and mammals) species and families reported in the Orinoco Delta region. State of knowledge classified as in Table 1.
