DOI: 10.5061/dryad.83bk3j9t8
title: Data for: Forecasting shifts in habitat suitability of three marine predators suggests a rapid decline in inter-specific overlap under future climate change

description: Aim: To estimate spatiotemporal changes in habitat suitability and
 inter-specific overlap among three marine predators: Baltic grey seals
 (Halichoerus grypus grypus), harbour seals (Phoca vitulina), and harbour
 porpoises (Phocoena phocoena) under contemporary and future conditions.
 Location: The southwestern region of the Baltic Sea, including the Danish
 Straits and the Kattegat, one of the fastest-warming semi-enclosed seas in
 the world. Methods: Location data (&gt;200 tagged individuals) were
 analysed within the maximum entropy (MaxEnt) algorithm to estimate changes
 in total area size and overlap of species-specific habitat suitability
 between 1997-2020 and 2091-2100. A total of eleven candidate predictor
 variables were considered representing anthropogenic activity,
 environmental, and climate sensitive oceanographic conditions in the area.
 Sea surface temperature and salinity data were taken from representative
 concentration pathways [RCPs] scenarios 6.0 and 8.5 to forecast potential
 climate change effects. Results: Model output suggests that habitat
 suitability of Baltic grey seals will decline drastically over space and
 time, largely driven by changes in sea surface salinity and a loss of
 currently available haulout sites following sea level rise in the future.
 A similar though weaker response was observed for harbour seals, while
 suitability of habitat for harbour porpoises was predicted to remain
 fairly stable over space and time. Inter-specific overlap in highly
 suitable habitat was predicted to increase slightly under RCP scenario 6.0
 when compared to contemporary conditions but to largely disappear under
 RCP scenario 8.5. Main conclusions: Marine predators in the southwestern
 Baltic Sea and adjacent waters may respond differently to future climatic
 conditions, leading to divergent shifts in habitat suitability that are
 likely to decrease inter-specific overlap. We, therefore, conclude that
 climate change can lead to a marked redistribution of area use by marine
 predators in the region, which may influence local food-web dynamics and
 ecosystem functioning.
description: Location data
 of Baltic grey seals
 (<em>Halichoerus
 grypus grypus</em>),
 harbour seals (<em>Phoca vitulina</em>), and harbour porpoises
 (<em>Phocoena
 phocoena</em>)
 were collected using GPS
 and ARGOS tags between 1997-2020 in the southwestern region
 of the Baltic Sea, including the Danish Straits and the
 Kattegat.  A total
 of eleven candidate predictor variables were generated
 representing anthropogenic
 activity, environmental, and climate sensitive oceanographic conditions in
 the area. Sea surface temperature and salinity data were taken from representative concentration pathways [RCPs]
 scenarios 6.0 and 8.5 to
 forecast potential climate
 change effects.
description: Data files with the extension .txt can be opened with a text
 editor, MS Excel and/or the open-source statistical program R.
 Data files with the extensions .gri and .grd are raster files
 that can be opened with QGIS, ArcGIS and /or the open-source statistical
 program R. Software files with the extension .R are
 code for statistical analyses of the data and can be opened with the
 open-source statistical program R.