Distribution, vertical position and ecological implications of shallow gas in Bahía Blanca estuary (Argentina)

BRAVO, MARÍA EMILIA; ALIOTTA, SALVADOR; FIORI, SANDRA; GINSBERG, SILVIA SUSANA

ESTUARINE COASTAL AND SHELF SCIENCE

ACADEMIC PRESS LTD-ELSEVIER SCIENCE LTD

Lugar: Amsterdam; Año: 2018 p. 222 - 231

0272-7714

There has been a growing interest in the study of shallow gas due its importance in relation to the marineenvironment, climate change and human activities. In Bahía Blanca estuary, Argentina, shallow gas has awide distribution. Acoustic turbidity and blanking are the main seismic evidence for the presence ofshallow gas in the estuary. The former prevails in the inner sector of the estuary where gas is either nearor in contact with the seabed. Gas deposits are generally associated with paleochannels corresponding tothe Holocene paleodeltaic environment. Distribution studies of shallow gas in this estuary are necessarybecause its presence implies not only a geological risk for harbor activities but also because it may havenoxious effects on the marine ecosystem, mainly on benthic communities. The comparison of benthiccommunities at a gas site (GS) with those at a control site (CS) indicated that gas could generateimpoverishment in terms of individuals´ abundance (GS: N ¼ 357; CS: N ¼ 724). Also, diversity indicesshowed great differences in the community structure at each site. This indicates that methane gas mayact as a natural disturbance agent in estuarine ecosystems. The presence of gas in seabed sediments musttherefore be taken into account when distribution studies are conducted of estuarine benthiccommunities.