Impacts of Marine heatwaves on the coralligenous formation of the North Adriatic Sea
Authors: Zunino Serena , Canu Donata , Bandelj Vinko , Drago Aldo , Galea De Giovanni Raisa , Ličer Matjaž , Misra Ankita , Petovic Slavica , Ponti Massimo , Previati Monica , Zammit Audrey , Solidoro Cosimo 
Published: March 2022

&lt;p&gt;Mediterranean marine heatwaves (MHW), defined as prolonged periods of anomalously warm sea temperatures, have been occurring more frequently and with higher intensity in recent years resulting in a degradation of the status of marine ecosystems. This work, which is part of the Interreg-Med project SHAREMED, aims to spatially assess MHW pressures and impacts on the coralligenous of the North Adriatic Sea. Coralligenous refers to complex biogenic structures made by the outgrowth of encrusting calcareous algae on hard substrata in the mesophotic zone and by several invertebrates, mostly Cnidaria, Polychaeta, Porifera and Bryozoa (Ballesteros et al., 2006&lt;sup&gt;1&lt;/sup&gt;).&amp;#160; The responses of the coralligenous assemblages to MHW ranges from bleaching, tissue necrosis and mortality events (Kruzic et al., 2014&lt;sup&gt;2&lt;/sup&gt;, Cerrano et al., 2000&lt;sup&gt;3&lt;/sup&gt;). Data on the distribution of the species and on their responses to temperature anomalous events were obtained by literature review, and database analysis (EMODnet, Reef Check database, Obis). MHW analysis followed the Hobday et al. (2016&lt;sup&gt;4&lt;/sup&gt;, 2018&lt;sup&gt;5&lt;/sup&gt;) methodology using both satellite data (CMEMS-Multidecadal L4-gridded satellite SST measurements from 1989 till present) and numerical modelling output (CMEMS-Mediterranean Sea Physics Reanalysis; 1987-2019).&lt;/p&gt;&lt;p&gt;First, the exposure maps were created in order to identify the overlap between MHW occurrences (in terms of duration, frequency and intensity) and the coralligenous outcrops.&amp;#160;&lt;/p&gt;&lt;p&gt;The MHW index maps were analysed in comparison to the historical data of mass mortality events reported in the literature (Di Camillo et al., 2012&lt;sup&gt;6&lt;/sup&gt;; Sini et al., 2015&lt;sup&gt;7&lt;/sup&gt;; Kruzic et al., 2016&lt;sup&gt;8&lt;/sup&gt;) to test the occurrence of MHW impacts.&amp;#160; A vulnerability index for coralligenous to MHW was developed, taking into account site-specific features such as indexes of diversity, richness and connectivity (Falace et al., 2015&lt;sup&gt;9&lt;/sup&gt;; Bandelj et al., 2020&lt;sup&gt;10&lt;/sup&gt;), and then used to evaluate the degree of impact on coralligenous formations by MHW following the methodology by Halpern et al., 2008&lt;sup&gt;11&lt;/sup&gt;.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;&lt;sup&gt;References:&lt;/sup&gt;&lt;/p&gt;&lt;p&gt;&lt;sup&gt;1&lt;/sup&gt;doi:10.1201/9781420006391-7; &lt;sup&gt;2&lt;/sup&gt;doi:10.3354/meps10962; &lt;sup&gt;3&lt;/sup&gt;doi:10.1046/j.1461-0248.2000.00152.x; &lt;sup&gt;4&lt;/sup&gt;doi:10.1016/j.pocean.2015.12.014; &lt;sup&gt;5&lt;/sup&gt;doi:10.5670/oceanog.2018.205; &lt;sup&gt;6&lt;/sup&gt;doi:10.1007/s10750-011-0877-z; &lt;sup&gt;7&lt;/sup&gt;doi:10.1371/journal.pone.0126253; &lt;sup&gt;8&lt;/sup&gt;doi:10.1111/maec.12293; &lt;sup&gt;9&lt;/sup&gt;doi:10.1371/journal.pone.0140931; &lt;sup&gt;10&lt;/sup&gt;doi:10.1016/J.ECSS.2020.106978; &lt;sup&gt;11&lt;/sup&gt;doi:10.1126/science.1149345&lt;/p&gt;