Marine Invertebrates of commercial interest at North of San Jorge Gulf, Patagonia, Argentina

Study Extent

Survey was conducted at the North of San Jorge Gulf shoreline, to estimate the abundance and biomass of bivalves and volutids of commercial interest. The sampling place was selected for its logistic for artisanal fishermen, proximity to the Camarones with accessibility by truck and zodiac boat and the informal knowledge in the area as susceptible to being marine protected area (MPA).

Sampling

The design of the survey was of fixed transects for visual census by SCUBA diving. Sampling included 32 transects settled from South to North from 5m to 23m of deph. The transects were separated every 1300 m (exposed areas), 650m ( moderately protected areas) and 325 m (bays). The diver counted and recorded every 150m bivalves and volutids in a line of 1m wide covering strip of 150m2. Representative specimens of gastropods and infaunal and epibenthic bivalves were collected. Complementary records of date, hour of start and end of each station, type of bottom and depth were included. The depth was taken with SCUBA diving computer and echo sound.

Quality Control

Taxonomy was verified by the curator of the Invertebrate Collection (CNP-INV) of the IBIOMAR CENPAT-CONICET, Dr. Javier Signorelli.

Method steps

1. The records were extracted from a hard copy report available in the CENPAT- CONICET library. For the preparation of data set, the species sampling event were integrated to the complementary tables of records of date, depth, abundace and biomass.

All specimens are marine volutids and marine bivalves identified to species level. The dataset included two species of volutid snails (Adelomelon ancilla, Odontocymbiola magellanica), two octopus and five species of Bivalvia (Aulacomya atra, Mytilus platensis, Ameghinomya antiqua, Aequipecten tehuelchus, Ensis macha).

1. Adelomelon ancilla
   common name: volutid gastropods rank: species
2. Odontocymbiola magellanica
   common name: volutid gastropods rank: species
3. Aulacomya atra
   common name: magellanic mussel rank: species
4. Mytilus platensis
   common name: blue mussel rank: species
5. Ameghinomya antiqua
   common name: clam rank: species
6. Aequipecten tehuelchus
   common name: scallop rank: species
7. Ensis macha
   common name: razor shell rank: species

South coastline of the Chubut Province, the Golfo San Jorge is representative sector of the Atlantic marine coast belonging to the Magellanic Province. It is part of the MPA (Parque Interjurisdiccional Marino Costero de la Patagonia Austral) https://www.parquesnacionales.gob.ar/areas-protegidas/region-patagonia/pim-costero-patagonia-austral/. The coast has bays as protected environments and rocky tips exposed to the waves. The beach has muddy substrates and fine sand. The reefs and numerous islands and islets give the area features that differentiate it from the rest of the Patagonian coastline.