**3.1 Invertebrates**

#### **3.1.1 Benthos**

72 Ecosystems Biodiversity

and range from the abiotic to the biotic. In general, the number of publications has increased for most of the themes, with studies related to fish and fisheries the most prolific (Figure 3).

Fig. 3. Number of publications by themes between 1950 and 2008 related to the Orinoco

Delta and the Gulf of Paria.

A total of at least 809 species-level taxa have been reported on benthic communities, from 5 animal phyla, 2 plant phyla (algae and angiospermae: mangroves and seagrasses) and only one group of protists (Foraminifera). Within these benthic communities, the group with the highest diversity is the crustaceans, with 310 species and 91 families reported, with amphipods and decapods comprising the greatest number (or highest percentage). The amphipod species are mainly marine, while decapods are represented by both marine and estuarine species. Mollusks represent the second most diverse group, with 189 species and 83 families, comprised of gastropods and bivalves (Table 1).

Phytobenthos are dominated by benthic algae, with 135 species and 33 families. Although eight seagrass species have been reported for the coast of Venezuela, none has been reported for the delta, only for the Gulf of Paria (Vera, 1992). The absence of seagrasses and benthic macroalgae might be a consequence of high loads of suspended matter and a lack of suitable substrates (Conde, 2000). The dominant terrestrial vegetation of the delta is the mangroves, with a mangrove formation between the Gulf of Paria and the Orinoco Delta representing more than 73% (183,500ha) of Venezuela's mangrove forest (Conde & Alarcón, 1993). Dominant mangrove species are the red mangrove *Rhizophora mangle*, the black mangrove *Avicennia germinans* and the white mangrove *Laguncularia racemosa*, though *R. harrisonii* and *R. racemosa*, the other two species of red mangrove have also been reported for the mid-delta (Pannier, 1979; Conde & Alarcón, 1993).

Biodiversity and Conservation of the Estuarine

barnacles and polychaetes (Table 2).

Chordata

**Kingdom Phylum or Class Class or Order** 

and Marine Ecosystems of the Venezuelan Orinoco Delta 75

Within the meroplankton, a total of 136 species have been reported, of which the decapod larval stages are the most important and diverse component. These larvae include species of shrimps with commercial value, such as species of the genus *Farfantepenaeus*, bivalves,

Monera Cyanophycota 8 39 1 Plantae Bacillariophyta 33 150 4 Chlorophyta 7 24 1 Crisophyta 2 3 1 Euglenophycota 1 6 1 Pyrrophycophyta 14 70 3 Animalia Cnidaria Hydrozoa 15 29 1 Cnidaria Scyphozoa 2 2 1 Ctenophora Beroida 1 1 1 Annelida Polychaeta 5 9 1 Mollusca Gastropoda 6 10 1 Crustacea Amphipoda 21 54 3

Crustacea Branchiopoda 3 3 1

 Crustacea Copepoda 30 116 3 Crustacea Decapoda 1 2 1 Crustacea Diplostraca 5 7 1 Crustacea Euphasiacea 1 12 2 Crustacea Isopoda 2 2 1 Crustacea Mysida 1 1 1 Crustacea Sessilia 1 6 1 Crustacea Stomatopoda 4 6 1 Crustacea Tanaidacea 2 2 1 Echinodermata Holothuroidea 1 1 1 Chaetognatha 3 10 1 Chordata Appendicularia 2 8 1

Urochordata

Table 2. Number of planktonic invertebrate species and families reported in the Orinoco

**TOTAL 173 575** 

Delta region. State of knowledge classified as in Table 1.

(Thaliacea) 2 2 1

**Described families** 

**Described species** 

**State of knowledge** 


Table 1. Number of benthic foraminifera, plant, and invertebrate species and families reported in the Orinoco Delta region. State of knowledge classified as: 5 = very well known (>80% described, and current taxonomic expertise); 4 = well known (>70% described, some taxonomic expertise); 3 = poorly known (<50% species described, no present expertise within region); 2= very poorly known (only few species recorded, no expertise); 1 = unknown (no species recorded, no expertise).

#### **3.1.2 Plankton**

The phytoplankton community in the area is comprised of Bacillariophyta with 150 species, Pyrrophycophyta (70 species), Cyanocophyta (39 species), Chlorophyta (24 species), Euglenophyta (6 species), and Crisophyta (3 species). Phytoplankton are distributed within two zones: the first dominated by an estuarine community, represented mainly by dinoflagellates, diatoms and chlorophytes, while the second consists of a marine habitat in which marine diatoms make up almost 80% of the community assemblage (Martín & Bone, 2007).

The zooplankton community in the area consists of 283 species of which 211 are crustaceans. Copepods dominate the holoplanktonic component with 116 species. Other groups are the gelatinous organisms, such as the hydrozoans (29 species) and the jellyfish (2 species).

Protista Foraminifera 13 29 2 Plantae Algae Chlorophyta 7 23 3 Algae Phaeophyta 4 13 3 Algae Rhodophyta 22 99 3 Angiospermae (mangroves) 3 5 4 Angiospermae (seagrasses) 1 1 4 Animalia Cnidaria Scyphozoa 1 1 1 Sipuncula 4 10 1 Annelida Polychaeta 39 94 3 Mollusca Bivalvia 30 83 3 Mollusca Cephalopoda 4 9 2 Mollusca Gastropoda 48 96 3 Mollusca Scaphopoda 1 1 1 Crustacea Amphipoda 32 143 3 Crustacea Cumacea 2 3 1 Crustacea Decapoda 43 142 3 Crustacea Isopoda 10 18 1 Crustacea Stomatopoda 1 1 1 Crustacea Tanaidacea 3 3 1 Chelicerata Pycnogonida 1 1 1 Echinodermata Asteroidea 4 13 3 Echinodermata Crinoidea 2 3 1 Echinodermata Echinoidea 4 9 2 Echinodermata Holothuroidea 3 2 1 Echinodermata Ophiuroidea 6 7 1

**TOTAL 288 809** 

unknown (no species recorded, no expertise).

assemblage (Martín & Bone, 2007).

**3.1.2 Plankton** 

Table 1. Number of benthic foraminifera, plant, and invertebrate species and families reported in the Orinoco Delta region. State of knowledge classified as: 5 = very well known (>80% described, and current taxonomic expertise); 4 = well known (>70% described, some taxonomic expertise); 3 = poorly known (<50% species described, no present expertise within region); 2= very poorly known (only few species recorded, no expertise); 1 =

The phytoplankton community in the area is comprised of Bacillariophyta with 150 species, Pyrrophycophyta (70 species), Cyanocophyta (39 species), Chlorophyta (24 species), Euglenophyta (6 species), and Crisophyta (3 species). Phytoplankton are distributed within two zones: the first dominated by an estuarine community, represented mainly by dinoflagellates, diatoms and chlorophytes, while the second consists of a marine habitat in which marine diatoms make up almost 80% of the community

The zooplankton community in the area consists of 283 species of which 211 are crustaceans. Copepods dominate the holoplanktonic component with 116 species. Other groups are the gelatinous organisms, such as the hydrozoans (29 species) and the jellyfish (2 species).

**Described families** 

**Described species** 

**State of knowledge** 

**Kingdom Phylum or Class Class or Order**

Within the meroplankton, a total of 136 species have been reported, of which the decapod larval stages are the most important and diverse component. These larvae include species of shrimps with commercial value, such as species of the genus *Farfantepenaeus*, bivalves, barnacles and polychaetes (Table 2).


Table 2. Number of planktonic invertebrate species and families reported in the Orinoco Delta region. State of knowledge classified as in Table 1.

Biodiversity and Conservation of the Estuarine

**Theme Author**

Exploratory fisheries Delta Ramos *et al.* (1982) Artisanal fisheries Warao Ponte & Mochcco (1997)

Shrimp and *curito* fisheries Novoa (1982c, 1982d)

Warao ethno-ichthyology Ponte (1995)

Fisheries resources Orinoquia Novoa (2002)

Trophic ecology Ponte (1990)

Biodiversity Morichal Largo Antonio & Lasso (2003)

Hydrology, vegetation and environmental Impact

Effects of shrimp trawling

History and socioeconomy of

Fisheries Delta and Gulf of

Taxonomy, biogeography and

Biodiversity and community

Community ecology Gulf of

Biodiversity Biosphere Reserve

of Paria, and the Venezuelan Atlantic Front.

Biodiversity Gran Morichal

Guyana

fisheries

fisheries

Paria

ecology

ecology

Paria

Orinoco Delta

Reserve

Exploratory fisheries Delta and

and Marine Ecosystems of the Venezuelan Orinoco Delta 77

Ginés *et al.* (1971, 1972)

Sánchez-Duarte (2011)

Novoa (1982a, 1982b)

Evaluation of fishing potential Achury *et al.* (2006), Schneider *et al.* (2007), Lasso-Alcalá

Biology of commercial species Novoa & Ramos (1982), Lasso & Sánchez-Duarte (2011) Exploratory fisheries Ramos *et al.* (1982), Lasso & Sánchez-Duarte (2011) Taxonomy and bio-ecology Cervigón (1982), Lasso & Sánchez-Duarte (2011)

Sánchez-Duarte (2011)

Biogeography Cervigón (1985), Lasso (1993), Lasso & Sánchez-Duarte

Biodiversity Orinoco Delta Ponte *et al.* (1999), Lasso-Alcalá & Lasso (2007), Lasso *et* 

Sánchez-Duarte (2011) Community ecology Delta Lasso *et al.* (2004 a, 2004b), Lasso & Sánchez-Duarte

Bone *et al.* (2004), Ortaz *et al*. (2007)

Fisheries catalog for the Delta Novoa *et al.* (1982), Lasso & Sánchez-Duarte (2011)

Duarte (2011)

*et al*. (2008)

(2011)

(2011)

Duarte (2011)

Campo (2004)

Biodiversity and ecology Lasso *et al.* (2008), Lasso & Sánchez-Duarte (2011) Alien and introduced Species Martínez-Escarbassiere *et al.* (2003), Lasso-Alcalá *et al.*

Table 4. Summary of the main publications by theme related to the Orinoco Delta, the Gulf

Exploratory fisheries Platform Cervigón (1965), Ginés & Cervigón (1968)

Monente & Colonnello (1997, 2004), Colonnello (2004)

Novoa (2000a), Lasso *et al*. (2002, 2004b, 2008), Lasso &

Novoa (2000b), Bone *et al.* (2004), Lasso &Sánchez-

Cervigón (1985), Lasso *et al.* (2009), Lasso-Alcalá &Lasso (2007), Lasso-Alcalá *et al.* (2008), Lasso &

Ponte & Lasso (1994), Jorgensen *et al.* (2000), Lasso *et al.* (2002), Lasso-Alcalá *et al.* (2008), Lasso & Sánchez-

Lasso & Meri (2003), Lasso-Alcalá *et al.* (2008), Lasso &

(2005a, 2005b, 2009), Lasso & Sánchez-Duarte (2011)

*al*. (2009), Lasso & Sánchez-Duarte (2011)
