Climatic change in the Antarctic Peninsula has driven profound shifts in the seabed.
The Antarctic Peninsula is among the places on Earth that registered major warming in the last 60 yr. Massive ice losses, represented by glacier retreat, ice‐shelf collapses and sea‐ice reduction are among the main impacts of this regional warming. The loss of sea‐bed ice coverage, on the one hand has been affecting benthic assemblages, but on the other it is opening up new areas for benthic colonisation. Potter Cove (South Shetland Islands) offered the opportunity of assessing both processes. We recently reported a sudden shift of benthic assemblages related to increased sedimentation rates caused by glacier retreat. This glacier retreat also uncovered a new island that presents a natural experiment to study Antarctic benthic colonisation and succession. We sampled the new island by photo‐transects taken up to 30 m depth. Here, we report an unexpected benthic assemblage characterised by high species richness, diversity and structural complexity with a well‐developed three‐dimensional structure and epibiotic relationships. Filter feeders comprised the largest trophic group at all depths, mainly ascidians, sponges and bryozoans. Densities were also surprising, recording only six ascidian species with a mean of ∼310 ind. m–2. These values are at least an order of magnitude higher than previous Antarctic reports on early colonisation. This finding challenges the extended idea of a slow and continuous recruitment in Antarctica. However, it also opens the question of whether these complex assemblages could have been present under the glacier in ice‐free refuges that are now exposed to open sea conditions. Under the current scenario of climate change, these results acquire high relevance as they suggest a two‐fold effect of the Antarctic Peninsula warming: the environmental shifts that threaten coastal ecosystems, and also the opening up of new areas for colonisation that may occur at a previously unimagined speed.
Ports are a key factor in the understanding and solving of most problems associated with marine invasive species across regional and global scales. Yet many regions with active ports remain understudied. The aim of this work was to (a) identify and quantify the marine fouling organisms in all Patagonian ports of Argentina classifying them as native, exotic or cryptogenic species through a rapid assessment survey and experimental studies, (b) survey the environmental and anthropogenic variables of these ports and (c) analyze and discuss these results in the light of the South America context for the study of marine invasive species, legislation and commerce. We found 247 fouling species, including 17 introduced, one of which is a new record for the region, and other 15 species currently considered cryptogenic species that will need further attention to clarify their status. The analysis of mobile and sessile taxa, together with the environmental variables measured in this study and the port movement, allow us to discuss individual ports' vulnerability to future introductions. This is the first large scale study performed for this region on this topic, and it will help in developing monitoring programs and early detection plans to minimize new species introductions along the marine coastline of southern South America.
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