Patagonia invertebrate densities

The kelp forests of southern Patagonia have a large diversity of habitats,
with remote islands, archipelagos, peninsulas, gulfs, channels, and
fjords, which are comprised of a mixture of species with temperate and
sub-Antarctic distributions, creating a unique ecosystem that is among the
least impacted on Earth. We investigated the distribution, diversity, and
abundance of marine macroinvertebrate assemblages from the kelp forests of
southern Patagonia over a large spatial scale and examined the
environmental drivers contributing to the observed patterns in assemblage
composition. We analyzed data from 120 quantitative underwater transects
(25 x 2 m) conducted within kelp forests in the southern Patagonian fjords
in the Kawésqar National Reserve (KNR), the remote Cape Horn (CH) and
Diego Ramírez (DR) archipelagos of southern Chile, and the Mitre Peninsula
(MP) and Isla de los Estados (IE) in the southern tip of Argentina. We
observed rich assemblages of macroinvertebrates among these kelp forests,
with a total of 185 unique taxa from 10 phyla and 23 classes/infraorders
across the five regions. The number of taxa per transect was highest at
IE, followed by MP, CH, and KNR, with the lowest number recorded at DR.
The trophic structure of the macroinvertebrate assemblages was explained
mostly by wave exposure (28% of the variation), followed by salinity (12%)
and the KNR region (11%). KNR was most distinct from the other regions
with a greater abundance of deposit feeders, likely driven by low salinity
along with high turbidity and nutrients from terrigenous sources and
glacial melt. Our study provides the first broad-scale description of the
benthic assemblages associated with kelp forests in this vast and
little-studied region and helps to establish baselines for an area that is
currently lightly influenced by local anthropogenic factors and less
impacted by climate change compared with other kelp forests globally.