Microbiological characterization of a semi-enclosed sub-Antarctic environment: the Straits of Magellan.

Among sub-Antarctic ecosystems, the microbiology
of the Straits of Magellan has been poorly
documented due to the scarcity of observations. In this
context, the spatial distribution of microbiological parameters,
both in terms of abundance (total picoplankton and
picophytoplankton, cultivable heterotrophic bacteria) and
biochemical assays (adenosine triphosphate and lipolysaccharide
estimations, as well as electron transport system
activity), was investigated in the epipelagic layer along the
Straits during late summer 1991 and early autumn 1995.
The microbial dynamics showed significant variations
along the Straits, with increasing values generally determined
eastward both in 1991 and 1995. Microbiological
results were additionally correlated with available data on
the physico-chemical and biological properties of the
analyzed water masses. Taking into consideration the
whole dataset, the principal component analysis led to the
identification of three main macro-areas along the Straits of
Magellan (Paso Largo, Paso Ancho and Angostura/Isla
Isabel) with different trophic features. This held true when
the two cruises were individually considered, as well as
when comparing each macro-area between the two cruises.
Additionally, a first attempt to quantify the carbon flux
through the microbial compartment within the main identified
macro-areas was made. The present work will allow
the gaining of further understanding of the microbiology of
this under-investigated sub-Antarctic marine ecosystem.