Invertebrates San Matias gulf from shallows waters, Patagonia, Argentina

Study Extent

Survey was conducted at the Puerto Lobos 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, natural accessibility characteristics to get access by truck and zodiac boat, and the informal knowledge in the area of bivalves and volutids susceptible to being commercially exploited.

Sampling

The design of the survey was of fixed transects for visual census by SCUBA diving. Sampling included 29 transects perpendicular to the coast, from 5m to 30 m of deph, 8 oriented from West to East separated every 1800 m and 21 settled from South to North, separated every 1300m. The diver counted and recorded every 150m bivalves and volutids in a line of 1m wide covering 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 verify by the curator Dr. Javier Signorelli of the IBIOMAR CENPAT-CONICET.

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 occurrence tables were integrated to the complementary tables of records of date, hour of start and end of each station, and depth. Ciocco N. F. 1995 La marisquería mediante buceo en el Golfo San José (Chubut Argentina) Serie : Informes técnicos del plan de manejo integrado de la Zona Costera Patagónica (PNUD-GEF, FPN), 2(1):1-39 Ciocco N. F., M.L. Lasta & C. Bremec.1998. Pesquerías de bivalvos: mejillón, vieiras (Tehuelche y Patagónica) y otras especies. En : el Mar Argentino y sus recursos Pesqueros 2: 142-166 (Boschi ed.), INIDEP, Mar del Plata.

All specimens are marine volutids and marine bivalves identified to species level. The dataset included four species of volutid snails (Zidona dufresnei, Adelomelon beckii, Adelomelon ancilla, Odontocymbiola magellanica) and eight species of Bivalvia (Aulacomya atra, Mytilus platensis, Ameghinomya antiqua, Aequipecten tehuelchus, Ensis macha, Panopea abbreviata, Atrina seminuda y Ostrea Puelchana.

1. Aulacomya atra
   common name: magellanic mussel rank: species
2. Mytilus platensis
   common name: Blue mussel rank: species
3. Ameghinomya antiqua
   common name: Clam rank: species
4. Aequipecten tehuelchus
   common name: Scallop rank: species
5. Ensis macha
   common name: Razor shell rank: species
6. Panopea abbreviata
   common name: Giant clam rank: species
7. Atrina seminuda
   common name: Half-naked pen shell rank: species
8. Ostrea Puelchana
   common name: Oyster rank: species
9. Zidona dufresnei
   common name: Volutid gastropods rank: species
10. Adelomelon beckii
    common name: Volutid gastropods rank: species
11. Adelomelon ancilla
    common name: Volutid gastropods rank: species
12. Odontocymbiola magellanica
    common name: Volutid gastropods rank: species

Southeast area of the San Matias Gulf that boundaries with the San Jose Gulf. Puerto Lobos is the accessible point coast from the cliff. The beach has wide shelf (solid sandstone platform extending into the sea).The seabed is sand and mixed bottoms of gravel and sand, while the slope changes the depth in few meters. The weather is characterized by strong winds.The species presented range from 30m to 5m depth.