Projecting the impacts of rising seawater temperatures on the distribution of seaweeds around Japan under multiple climate change scenarios

Abstract

Seaweed beds play a key role in providing essential habitats and energy to coastal areas, with enhancements in productivity and biodiversity and benefits to human societies. However, the spatial extent of seaweed beds around Japan has decreased due to coastal reclamation, water quality changes, rising water temperatures, and heavy grazing by herbivores. Using monthly mean sea surface temperature (SST) data from 1960 to 2099 and SST-based indices, we quantitatively evaluated the effects of warming seawater on the spatial extent of suitable versus unsuitable habitats for temperate seaweed Ecklonia cava, which is predominantly found in southern Japanese waters. SST data were generated using the most recent multiple climate projection models and emission scenarios (the Representative Concentration Pathways or RCPs) used in the Coupled Model Intercomparison Project phase 5 (CMIP5). In addition, grazing by Siganus fuscescens, an herbivorous fish, was evaluated under the four RCP simulations. Our results suggest that continued warming may drive a poleward shift in the distribution of E. cava, with large differences depending on the climate scenario. For the lowest emission scenario (RCP2.6), most existing E. cava populations would not be impacted by seawater warming directly but would be adversely affected by intensified year-round grazing. For the highest emission scenario (RCP8.5), previously suitable habitats throughout coastal Japan would become untenable for E. cava by the 2090s, due to both high-temperature stress and intensified grazing. Our projections highlight the importance of not only mitigating regional warming due to climate change, but also protecting E. cava from herbivores to conserve suitable habitats on the Japanese coast.

Projected 21st‐century distribution of canopy‐forming seaweeds in the Northwest Atlantic with climate change

“…It will also depend on the availability of suitable substrate, where rocky coasts are typical along western Greenland and the Canadian Archipelagos but can be limiting elsewhere in the Arctic (Filbee‐Dexter et al, ). Similar trends are expected for seaweed populations across the Northern Hemisphere in Europe (Assis, Araújo et al, ; Franco et al, ; Jueterbock et al, ; Raybaud et al, ), the Arctic (Jueterbock, Smolina, Coyer, & Hoarau, ), and in Japan (Takao, Kumagai, Yamano, Fujii, & Yamanaka, ). Yet future studies are needed for the west coast of North America as well as Africa and South America.…”

“…The projected range expansions in the NW-Atlantic are possible as land masses connect temperate and Arctic seas thereby facilitating dispersal (Krause-Jensen & Duarte, 2014). Northward expansions of seaweeds will depend on each species' dispersal ability, as long-distance dispersal is possible via rafting (Fraser et al, 2018;Kalvas & Kautsky, 1998;Olsen et al, 2010;Trowbridge & Todd, 1999) or kelp zoospores (Reed, Laur, & Ebeling, 1988 (Assis, Araújo et al, 2018a;Franco et al, 2018;Jueterbock et al, 2013;Raybaud et al, 2013), the Arctic (Jueterbock, Smolina, Coyer, & Hoarau, 2016), and in Japan (Takao, Kumagai, Yamano, Fujii, & Yamanaka, 2015). Yet future studies are needed for the west coast of North America as well as Africa and South America.…”

Predictions of kelp distribution shifts along the northern coast of Japan

“…The distribution of kelps expanded and contracted with glacial and interglacial cycles because of the influence of temperature fluctuations (Assis et al ). Ongoing water temperature increases with global climate change is predicted to shift kelp distribution toward higher latitudes, as revealed in this study and others (Assis et al ; Assis et al ; Assis et al ; Franco et al ; Khan et al ; Müller et al ; Raybaud et al ; Takao et al ). In fact, shifts in the global distribution of kelp species have already been observed over the last five decades (Araújo et al ; Assis et al ; Filbee‐Dexter et al ; Kumagai et al ; Krumhansl et al ; Wernberg et al ).…”

Projected distributions of Southern Ocean albatrosses, petrels and fisheries as a consequence of climatic change

“…Our results are also consistent with Hazen et al (2012) which predicted range increases and poleward shifts for three procellariiform species in the northern Pacific Ocean. Range contraction and poleward shifts have been projected for several groups of marine and terrestrial organisms, including seaweed (Takao et al 2015, Marzloff et al 2016, marine fish (Lenoir et al 2011, Hazen et al 2012, Jones et al 2013, Sunday et al 2015, marine invertebrates (Cheung et al 2009, Stuart-Smith et al 2015, Sunday et al 2015, Marzloff et al 2016, marine mammals (Hazen et al 2012), insects (Beaumont and Hughes 2002, Kwon and Lee 2015, ticks (Williams et al 2015), terrestrial birds (Araújo et al 2005), and trees (Morin andThuiller 2009, Goberville et al 2015). Such changes were also projected to reflect in spatial redistribution of biodiversity with consequences for ecosystem functioning (Constable et al 2014, García Molinos et al 2015, Stuart-Smith et al 2015.…”