The Marine Biodiversity and Climate Change Project (MarClim) is a UK and Ireland-wide project that periodically monitors and reports on the biogeographical distributions of intertidal species in the context of ongoing climate change. The 2014-2015 and 2020-2022 studies repeated studies in 2002 and 2010 sites along the entire rocky coastline of Scotland. The 2014/15 survey was extended to include the Shetland Islands.
The main aim of the study was to look for changes in the geographical distribution and abundance of species in the context of recent climate change – principally temperature change – on both short- and long-term timescales. During 2020-2022 the project aimed to detect ongoing change in the biota of intertidal rocky shores around Scotland by conducting surveys at 167 locations over three summer seasons. The first phase began in late summer of 2020 following relaxation of Covid 19 travel restrictions and ended in late 2021 having completed a circuit of coastal sites in mainland Scotland, the Inner Hebrides (Mull and Skye) and Outer Hebrides (Barra to Lewis). The second phase took place from June to September 2022 and extended the survey domain to Orkney and Shetland, and the islands of Islay, Coll and Tiree in the Inner Hebrides. At each site, surveyors made categorical abundance estimates (ExSACFOR) of conspicuous species using a pre-defined checklist of taxa. Surveys also included digital images of shore views and of replicates areas of substratum at low, mid and high shore levels: smaller 40cm2 areas and 0.25m2 quadrats. Images were catalogued and retained for further species identification and quantification if required. Changes observed relative to earlier surveys included a small shift in community composition towards greater dominance by warm affinity species, but with a mix of increases and decreases in cold affinity species. The dataset provides the benchmark for ongoing assessments of change in biodiversity on rocky shores in Scotland.
