IOV Copépodos del Golfo de Cariaco, Venezuela

Study Extent

The eastern sector or sac of the Gulf of Cariaco, is approximately 9 km wide and 17 km long. The shallowest depths of the gulf are located in this sector, which is close to 40 meters. At its eastern end, the Carinicuao and Cariaco rivers flow out and in the south, the Oricoto and López ravines, making up the largest continental tributaries and probably the source of supply of much of the sedimentary materials deposited in the study area (Caraballo, 1982). The vegetation in this sector is characterized by the presence of mangroves and xerophytic zones.

Sampling

The design to take the samples was carried out utilizing a two-stage conglomerate sampling with a subsample (Cochran, 1977), which consisted of dividing the eastern sector or the Gulf sac into three zones; within each zone, three stations were chosen at random, for a total of 9 samples per outlet. The samples were collected monthly between July 2009 and January 2010, guaranteeing representativeness in the rainy season (July- September) and drought (October-December and February), in the nine seasons in the eastern sector of the Gulf of Cariaco

Method steps

1. The zooplankton samples were collected at the surface level, with a standard plankton net of 333 microns was used at a speed of 3.7 km/h for 15 min. This network was equipped with a flowmeter to estimate the volume of filtered water. All samples were immediately placed in 500 mL polyurethane bottles and stored in formalin buffered with sodium tetraborate, maintaining the final concentration at 5 %.
2. At each station, temperature, salinity, and surface dissolved oxygen were measured using a multi-parameter probe (YSI). Simultaneously, samples were collected in dark polyethylene bottles (2 L) for determinations of chlorophyll-a (Chlor.-a) using the spectrophotometric method described by Lorenzen modified by Strickland and Parsons (1972), the results were expressed in mg Clor.-a.m-3.
3. For taxonomic determination,from the concentrated samples (400 mL), 3 sub-samples of 5 mL were obtained with a Stempel pipette, and a count and identification of adult and juvenile copepods was carried out under the lowest possible taxonomic level, using the specialized identification keys of Campos-Hernández and Suárez-Morales (1994), Suárez-Morales (1995), Bradford-Grieve et al. (1999), as well as the Razouls et al. (2005-2019). The number of organisms counted was divided by the volume of filtered water, so the results were standardized to ind.m-3.

All copepods were identified up to species

1. Acartia (Acanthacartia) tonsa
   rank: species
2. Temora turbinata
   rank: species
3. Paracalanus quasimodo
   rank: species
4. Subeucalanus subcrassus
   rank: species
5. Subeucalanus subtenuis
   rank: species

This study was carried out in the eastern region of the Cariaco gulf, Sucre states, Venezuela