Prof Stephen Hawkins1,3, Prof Roger Herbert2, Dr Louise Firth3, Dr Mauricio Orostica4,5, Prof Stuart Jenkins4, Dr Sally Keith6, Dr Nova Mieszkowska7
1University of Southampton and Marine Biological Association of the UK, Southampton and Plymouth, UK, 2University of Bournemouth, Bournemouth, UK, 3University of Plymouth, Plymouth, UK, 4Bangor University, Bangor, UK, 5Universidad Adolfo Ibanez, Vina del Mar, , Chile, 6University of Lancaster, Lancaster, UK, 7University of Liverpool and Marine Biological Association of the UK, Liverpool and Plymouth, UK
Anthropogenic climate-change has been shown to drive the abundance and distribution of species; but it needs to be put into context of climate fluctuations as recent warming is not linear. Since initial broad-scale surveys by Crisp and Southward in the warm 1950s, both reduced abundance during the cooler 1960s, 1970s and early 1980s, and increased abundance and range expansions since the 1990s have been observed in warm-water invertebrate species towards their poleward limits in the English Channel. These increases in abundance and range extensions have continued since 2005, despite some cooler years (2009-2011, including coldest winter for 47 years). We also consider the underlying population dynamics of selected species. Ultimately warming drives increased reproductive output and hence recruitment, but it may increase probability of breaching barriers to spread. Range extensions have continued once proximate hydrographic barriers to dispersal were breached and habitat gaps crossed, despite recent cooling. Responses are highly idiosyncratic and aphasic reflecting dispersal capability and habitat requirements. Some species were detected spreading polewards from the early 2000s (Perforatus perforatus, Steromphala umbilicalis, Patella ulyssiponensis, Melaraphe neritoides, Phorcus lineatus – the latter further expanding from 2019), others more recently (Clibanarius 2016; Sabellaria alveolata 2020), some hardly at all as scattered individuals (Patella depressa 2012), or not at all (Chthamalus montagui and C.stellatus). Proliferating artificial habitat (S. umbilicalis, P.ulyssiponensis, M.neritoides, Phorcus lineatus) and relict Victorian Piers (P. perforatus) provide stepping-stones across habitat gaps. Counter-intuitively those species spreading least had longest larval lives, and that expanding the most had a short larval-life.
Presentation Slides – Stephen Hawkins
Biography:
Steve Hawkins has been researching rocky shores since 1975, taking an experimental approach to understand the role of biological interactions in determining community structure, plus biodiversity-ecosystem functioning relationships. He has been undertaking long-term and broad-scale observations in parallel to understand the interactions of climate-driven change with other impacts and processes determining biogeographic patterns. He also has worked on restoring disused dock basin ecosystems on highly urbanised coastlines and eco-engineering approaches for environmentally-sensitive sea defences. He has been attending ITRS since 1995. This may be his farewell tour…
