A song of wind and ice: increased frequency of marine cold-spells in southwestern Patagonia and their possible effects on giant kelp forests

• Main Authors: Mora-Soto, Alejandra, Aguirre, Catalina, Iriarte, Jose Luis, Palacios, Mauricio, Macaya, Erasmo C., Macias-Fauria, Marc
• Format: Other/Unknown Material
• Language: unknown
• Published: Zenodo 2022
• Subjects: MHW; MCS; marine heatwaves; marine cold-spells; kelp forests; kelp ecosystems; sub-antarctic; subantartic; Antarc*; Antarctic; Southern Ocean
• Online Access: https://doi.org/10.5061/dryad.905qfttm5

In contrast to other coastal regions of the world, the giant kelp ( Macrocystis pyrifera ) ecosystem in southwestern Patagonia has been persistent in area and associated biodi versity in the last decades. In this ecoregion, Sea Surface Temperature (SST) records have consistently remained below the upper thermal threshold for kelp survival, however no studies have analysed the spatiotemporal variability of SSTs and their anomalies across the geographical diversity of the southwestern Patagonian coastline. We explored the geographical distribution of extreme warm and cold events in this region from latitudes 47 ° to 56 ° S in a range of 1,000 km, identifying the dates and spatial distribution of Marine Heatwaves (MHWs) and Marine Cold-Spells (MCSs) from 1982 to 2020. Results sho w that a peak in the number of MHWs occurred in the great El Ni n o y ear of 1998. Additionally, the 2014-2019 period has had more severe and extreme MCSs than the pre vious decades. We discuss the origin of these events with a focus on three main processes: 1 ) geographically constrained cold events caused by glacier melting, 2) regional cold events caused by extreme winds linked to the position of the polar front, and 3) extensive SST anomalies link ed to planetary-scale events such as El Nino and La Nina. Overall, those processes were conductive to counteract global warming trends locally/regionally, high lighting southwestern Patagonia as a possible climatic refugium for the giant kelp ecosys tem. Despite this, the effects of freshwater inputs and storm turbulence on the exposed coasts facing the Southern Ocean may cause new kinds of stress on this ecosystem. Files in this dataset: Table S1 (SM_MHW_MCS_March2022.xlsx): List of MCSs (Categories II, III and IV); list of MHWs (Categories II, III and IV); Combined list of MCSs and MHWs, Categories III and IV. MCS per ecoregion; the complete series is in MCS_category_March2022.csv MHW per ecoregion; the complete series is in MHW_category_March2022.csv SST per ecoregion. We found a gap of ...