Expansion of vegetated coastal ecosystems in the future Arctic

Abstract

Warming occurs particularly fast in the Arctic and exerts profound effects on arctic ecosystems. Sea ice-associated ecosystems are projected to decline but reduced arctic sea ice cover also increases the solar radiation reaching the coastal seafloors with the potential for expansion of vegetated habitats, i.e., kelp forests and seagrass meadows. These habitats support key ecosystem functions, some of which may mitigate effects of climate change. Therefore, the likely expansion of vegetated coastal habitats in the Arctic will generate new productive ecosystems, offer habitat for a number of invertebrate and vertebrate species, including provision of refugia for calcifiers from possible threats from ocean acidification, contribute to enhance CO 2 sequestration and protect the shoreline from erosion. The development of models allowing quantitative forecasts of the future of vegetated arctic ecosystems requires that key hypotheses underlying such forecasts be tested. Here we propose a set of three key testable hypotheses along with a research agenda for testing them using a broad diversity of approaches, including analyses of paleo-records, space-for-time substitutions and experimental studies. The research agenda proposed would provide a solid underpinning to guide forecasts on the spread of marine macrophytes onto the Arctic with climate change and contribute to balance our understanding of climate change impacts on the arctic ecosystem through a focus on the role of engineering species. Anticipating these changes in ecosystem structure and function is key to develop managerial strategies to maximize these ecosystem services in a future warmer Arctic.

Climate Change Impacts on Seagrass Meadows and Macroalgal Forests: An Integrative Perspective on Acclimation and Adaptation Potential

“…How fast and far warm-temperate range edges will retract toward higher latitudes largely depends on the macrophytes' ability to rapidly acclimatize or adapt to warm temperature extremes. In contrast, how fast and far poleward range-edges will extend into polar regions does not only depend on suitable temperatures for reproduction, but also on the macrophytes' ability to adapt to the extreme polar light conditions with month-long winters of constant darkness, and month-long summers of constant light (Krause-Jensen and Duarte, 2014;Berge et al, 2015).…”

Long photoperiods sustain high pH in Arctic kelp forests

“…The potential threat to calcifiers has led to efforts to understand the controls on pH in their habitats, which include kelp forests and seagrass meadows ( 4 ). Calcifiers, such as bivalves, brittle stars, and sea urchins, thrive in coastal vegetated ecosystems ( 5 ), which not only provide them with food and shelter but also affect their pH environment ( 4 , 6 ). …”

“…Hence, it follows that the relative duration of the positive (day) versus the negative (night) period, that is, the photoperiod, should determine the overall effect. We therefore hypothesized that photoperiod should constrain diurnal fluctuations in pH and CO 2 and, hence, the potential role of vegetated habitats as buffers or amplifiers of OA effects ( 6 , 21 ). However, the role of photoperiod in constraining the effects of marine macrophytes on pH and CO 2 remains untested.…”

Survival of early life history stages of Arctic kelps (Kongsfjorden, Svalbard) under multifactorial global change scenarios

“…Brown algae of the order Laminariales (kelps) form subtidal forests along temperate and polar coasts and are among the most valuable and most productive ecosystems This article belongs to the special issue on the ''Kongsfjorden ecosystem -new views after more than a decade of research'', coordinated by Christian Wiencke and Haakon Hop. worldwide (Costanza et al 1997;Graham et al 2007;Krause-Jensen and Duarte 2014). In Arctic, western Svalbard kelp forests are composed of the biomass-dominant species Alaria esculenta (Linnaeus) Greville; Saccharina latissima (Linnaeus) C. E. Lane, C. Mayes, Druehl and G. W. Saunders; and Laminaria digitata (Hudson) J. V. Lamouroux (e.g.…”