The future of the northeast Atlantic benthic flora in a high CO₂ world

Abstract

Seaweed and seagrass communities in the northeast Atlantic have been profoundly impacted by humans, and the rate of change is accelerating rapidly due to runaway CO2 emissions and mounting pressures on coastlines associated with human population growth and increased consumption of finite resources. Here, we predict how rapid warming and acidification are likely to affect benthic flora and coastal ecosystems of the northeast Atlantic in this century, based on global evidence from the literature as interpreted by the collective knowledge of the authorship. We predict that warming will kill off kelp forests in the south and that ocean acidification will remove maerl habitat in the north. Seagrasses will proliferate, and associated epiphytes switch from calcified algae to diatoms and filamentous species. Invasive species will thrive in niches liberated by loss of native species and spread via exponential development of artificial marine structures. Combined impacts of seawater warming, ocean acidification, and increased storminess may replace structurally diverse seaweed canopies, with associated calcified and noncalcified flora, with simple habitats dominated by noncalcified, turf-forming seaweeds.

Potential and limitations of finite element modelling in assessing structural integrity of coralline algae under future global change

“…Consequently, a significant loss of rhodoliths from the North Atlantic by the year 2100 has been predicted (Brodie et al, 2014). However, laboratory experiments have shown highly varied responses to elevated levels of CO 2 .…”

The regulation of coralline algal physiology, an in situ study of <i>Corallina officinalis</i> (Corallinales, Rhodophyta)

“…Water temperature profoundly influences the survival, recruitment, growth and reproduction of macroalgal species (Breeman, 1988) and is a key factor governing both the small-and largescale distribution of species (Breeman, 1988;Luning, 1990;Jueterbock et al, 2013). With continued increases in water temperatures, some macroalgal species and populations may become chronically (gradual warming) or acutely (extreme events) stressed as temperatures exceed physiological thresholds (Brodie et al, 2014). With OA-driven increases in seawater dissolved organic carbon (DIC) concentrations, several studies have predicted a positive response of macroalgal photosynthesis (Marberly, 1990;Johnston et al, 1992), though with notable exceptions (Israel and Hophy, 2002).…”

“…The abilities to control ion transport across membranes and internal pH regulation are therefore likely to be major factors in determining calcified macroalgal responses to OA (Koch et al, 2013). It is therefore critical to constrain Corallina ecophysiology in relation to current environmental variability in order to aid projections under future climate scenarios (Nelson, 2009;Koch et al, 2013;Brodie et al, 2014;Hofmann and Bischof, 2014). It is also important to understand the present-day role of these dominant community members in coastal carbon cycles and how this may change into the future (van der Heijden and Kamenos, 2015).…”

The network BiodiversityKnowledge in practice: insights from three trial assessments

“…It was chosen because kelp-dominated assemblages play fundamental ecological roles in temperate and polar coastal areas around the world (Mann 2000;Steneck et al 2002), providing habitat, food and shelter for other organisms and supplying many ecosystem services (Duggins et al 1989;Norderhaug et al 2005;Reisewitz et al 2006). For this reason it is concerning that kelps are receding in several regions due to the impact of harvesting and other anthropogenic pressures (Smale et al 2013;Brodie et al 2014). While a number of local observations suggest that this may be the case also in Europe, the existing knowledge about the status and trends of European kelp forests and the ecosystems services they provide is limited and fragmented (Araújo et al 2013;Smale et al 2013).…”