Ocean acidification impacts on coastal ecosystem services due to habitat degradation

Abstract

The oceanic uptake of anthropogenic carbon dioxide emissions is changing seawater chemistry in a process known as ocean acidification. The chemistry of this rapid change in surface waters is well understood and readily detectable in oceanic observations, yet there is uncertainty about the effects of ocean acidification on society since it is difficult to scale-up from laboratory and mesocosm tests. Here, we provide a synthesis of the likely effects of ocean acidification on ecosystem properties, functions and services based on observations along natural gradients in pCO2. Studies at CO2 seeps worldwide show that biogenic habitats are particularly sensitive to ocean acidification and that their degradation results in less coastal protection and less habitat provisioning for fisheries. The risks to marine goods and services amplify with increasing acidification causing shifts to macroalgal dominance, habitat degradation and a loss of biodiversity at seep sites in the tropics, the sub-tropics and on temperate coasts. Based on this empirical evidence, we expect ocean acidification to have serious consequences for the millions of people who are dependent on coastal protection, fisheries and aquaculture. If humanity is able to make cuts in fossil fuel emissions, this will reduce costs to society and avoid the changes in coastal ecosystems seen in areas with projected pCO2 levels. A binding international agreement for the oceans should build on the United Nations Sustainable Development Goal to ‘minimise and address the impacts of ocean acidification’.

Diatoms Dominate and Alter Marine Food-Webs When CO2 Rises

“…Increasing CO 2 levels were accompanied by a shift from diverse benthic communities of corals and macroalgae to a diatom turf community. Similar general patterns are seen at CO 2 seeps in tropical, sub-tropical, and temperate coastal systems with algal dominance, habitat degradation, and loss of biodiversity in acidified areas [66]. Diatom and turf algal blooms have been observed at other CO 2 seeps, for example, at the temperate White Island CO 2 seep in New Zealand where turf algae outcompete kelp [61].…”

Effects of Ocean Acidification on Marine Photosynthetic Organisms Under the Concurrent Influences of Warming, UV Radiation, and Deoxygenation

“…under controlled conditions, and data on the effects of OA on complex communities in natural environments are relatively limited (Riebesell and Gattuso, 2015;Boyd et al, 2018), although experiments at volcanic seeps and using mesocosms have shown that increased pCO 2 benefits some algae more than others and that lower carbonate saturation states harm some algae more than others. So while most benthic algae are tolerant of OA conditions, changes in carbonate chemistry cause large changes in algal community composition and ecosystem function (Hofmann et al, 2012;Hall-Spencer and Harvey, 2019). The combined effects of OA with other drivers, such as warming, increased UV exposure or deoxygenation, are expected to alter marine communities with effects that differ regionally.…”

Combined salinity and acidity stressors alterDaphnia magnapopulation growth and structure under severe absence of photoperiod

“…In fact, CO2-dependent freshwater acidification is a major new challenge for zooplankton; shown by Weiss et al (2018) to lead to impairment of Daphnia detection of predators with consequences for the entire freshwater ecosystem [70]. Those impacts may worsen when ‘acidified’ saltwater intrudes the land by rising sea levels [71,72].…”

“…, acid rain [81] alongside with organic acids from land catchments and acid deposition on a local scale [78], pond draining [82] and drainage waters particularly in areas with soils originated from granite or weathering-resistant mineral aggregates [77,83], atmospheric and soil deposition of sulphur [78,80, 84], land use and management policies [80,83], afforestation [80] and mobilisation of acid anions, via heavy rain, following forest fires and draughts [80,85–87], use of nitrogen-based fertilisers [88], melt of snow rich in sulphuric and nitric compounds [81,83,84], and increased levels of carbon dioxide and pCO2 in water [70,89,90]. Indeed, water acidification are projected to lead to alarming ecological consequences overtime [70–72,75,89–91].…”