INVESTIGADORES
DALEO Pedro
artículos
Título:
The distribution and ecological effects of the introduced Pacific oyster Crassostrea gigas (Thunberg, 1793) in Northern Patagonia
Autor/es:
ESCAPA, M; ISACCH, J.P.; DALEO, P.; ALBERTI, J.; IRIBARNE, O.; BORGES, M.; DOS SANTOS, E.P.; GAGLIARDINI, D.A; LASTA, M.
Revista:
JOURNAL OF SHELLFISH RESEARCH
Referencias:
Año: 2004 vol. 23 p. 765 - 772
ISSN:
0730-8000
Resumen:
In this work we studied the actual coverage, distribution patterns
and ecological effects of the introduced oyster Crassostrea gigas 20 years after their introduction to the Northern
Argentinean Patagonia (Bahía Anegada; 39º 50 to 40º 40 S and 61º 59 a 62º 28 W). Using
satellite imagery and field and aerial inspections we found 10 oyster beds that
cover less than 0.05% of the bay intertidal (area covered: 36.45 ha). These beds are
restricted to intertidal zones with superficial hard substrata (limestone
outcrops). Most epifaunal organisms (the crabs Cyrtograpsus angulatus, Chasmagnathus
granulatus, the isopod Melita palmata, and the snail Heleobia australis) showed higher densities inside oyster beds compared with outside
and experiments showed that artificially deployed oyster beds increased the
densities of their at three intertidal zones (high intertidal marsh, low
intertidal marsh and low intertidal with hard substrata) and also increased
densities of infaunal organisms (the polychaetes Laeonereis acuta, Nepthys
fluviatilis, and the priapulid Priapulus tuberculatospinosus) at the
low intertidal with hard substrata. This may be the result of increasing
habitat structure and refuge for epifaunal organisms, and enhancement of
deposition and sediment stability that may benefit infaunal organisms.
Densities bird species (Local species: Larus
dominicanus, Haematopus palliatus;
Regional migratory shorebird: Charadrius
falklandicus; Long range migratory shorebirds: Pluvialis dominica,
Calidris canutus Tringa flavipes) were higher inside oyster beds compared with
similar zones without oysters, which may be the result of higher prey
availability. Foraging rate was also higher for some of these species (P. dominica, C. falklandicus).
However, due to the limited availability of hard substratum the aerial
distribution of oysters is small. In conclusion, the ecological effects of this
introduction are not negative, there was an increase in species abundance and
the area were preferred by local and migratory bird species, which also showed
higher feeding rates.