Ocean acidification represents a threat to marine species worldwide, and forecasting the ecological impacts of acidification is a high priority for science, management, and policy. As research on the topic expands at an exponential rate, a comprehensive understanding of the variability in organisms' responses and corresponding levels of certainty is necessary to forecast the ecological effects. Here, we perform the most comprehensive meta-analysis to date by synthesizing the results of 228 studies examining biological responses to ocean acidification. The results reveal decreased survival, calcification, growth, development and abundance in response to acidification when the broad range of marine organisms is pooled together. However, the magnitude of these responses varies among taxonomic groups, suggesting there is some predictable trait-based variation in sensitivity, despite the investigation of approximately 100 new species in recent research. The results also reveal an enhanced sensitivity of mollusk larvae, but suggest that an enhanced sensitivity of early life history stages is not universal across all taxonomic groups. In addition, the variability in species' responses is enhanced when they are exposed to acidification in multi-species assemblages, suggesting that it is important to consider indirect effects and exercise caution when forecasting abundance patterns from single-species laboratory experiments. Furthermore, the results suggest that other factors, such as nutritional status or source population, could cause substantial variation in organisms' responses. Last, the results highlight a trend towards enhanced sensitivity to acidification when taxa are concurrently exposed to elevated seawater temperature.

/pdf/impacts-of-ocean-acidification-on-marine-organisms-j52whpzuru.pdf

Impacts of ocean acidification on marine organisms: quantifying sensitivities and interaction with warming

Ocean acidification is a pervasive stressor that could affect many marine organisms and cause profound ecological shifts. A variety of biological responses to ocean acidification have been measured across a range of taxa, but this information exists as case studies and has not been synthesized into meaningful comparisons amongst response variables and functional groups. We used meta-analytic techniques to explore the biological responses to ocean acidification, and found negative effects on survival, calcification, growth and reproduction. However, there was significant variation in the sensitivity of marine organisms. Calcifying organisms generally exhibited larger negative responses than noncalcifying organisms across numerous response variables, with the exception of crustaceans, which calcify but were not negatively affected. Calcification responses varied significantly amongst organisms using different mineral forms of calcium carbonate. Organisms using one of the more soluble forms of calcium carbonate (high-magnesium calcite) can be more resilient to ocean acidification than less soluble forms (calcite and aragonite). Additionally, there was variation in the sensitivities of different developmental stages, but this variation was dependent on the taxonomic group. Our analyses suggest that the biological effects of ocean acidification are generally large and negative, but the variation in sensitivity amongst organisms has important implications for ecosystem responses.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1461-0248.2010.01518.x

Meta‐analysis reveals negative yet variable effects of ocean acidification on marine organisms

Global increases in atmospheric CO2 and temperature are associated with changes in ocean chemistry and circulation, altering light and nutrient regimes. Resulting changes in phytoplankton community structure are expected to have a cascading effect on primary and export production, food web dynamics and the structure of the marine food web as well the biogeochemical cycling of carbon and bio-limiting elements in the sea. A review of current literature indicates cell size and elemental stoichiometry often respond predictably to abiotic conditions and follow biophysical rules that link environmental conditions to growth rates, and growth rates to food web interactions, and consequently to the biogeochemical cycling of elements. This suggests that cell size and elemental stoichiometry are promising ecophysiological traits for modelling and tracking changes in phytoplankton community structure in response to climate change. In turn, these changes are expected to have further impacts on phytoplankton community structure through as yet poorly understood secondary processes associated with trophic dynamics.

https://www.mmab.ca/pubs/finkel-2010-jpr-changing-world-119.pdf

Phytoplankton in a changing world: cell size and elemental stoichiometry

Prediction of the impact of global climate change
on marine HABs is fraught with difficulties. However,
we can learn important lessons from the fossil
record of dinoflagellate cysts; long-term monitoring
programs, such as the Continuous Plankton Recorder
surveys; and short-term phytoplankton community
responses to El Nin˜o Southern Oscillation
(ENSO) and North Atlantic Oscillation (NAO) episodes.
Increasing temperature, enhanced surface
stratification, alteration of ocean currents, intensification
or weakening of local nutrient upwelling,
stimulation of photosynthesis by elevated CO2,
reduced calcification through ocean acidification
(‘‘the other CO2 problem’’), and heavy precipitation
and storm events causing changes in land runoff
and micronutrient availability may all produce contradictory
species- or even strain-specific responses.
Complex factor interactions exist, and simulated
ecophysiological laboratory experiments rarely allow
for sufficient acclimation and rarely take into
account physiological plasticity and genetic strain
diversity. We can expect: (i) range expansion of
warm-water species at the expense of cold-water species,
which are driven poleward; (ii) speciesspecific
changes in the abundance and seasonal
window of growth of HAB taxa; (iii) earlier timing of
peak production of some phytoplankton; and (iv)
secondary effects for marine food webs, notably
when individual zooplankton and fish grazers are differentially
impacted (‘‘match-mismatch’’) by climate
change. Some species of harmful algae (e.g., toxic
dinoflagellates benefitting from land runoff and ⁄ or
water column stratification, tropical benthic dinoflagellates
responding to increased water temperatures
and coral reef disturbance) may become more successful,
while others may diminish in areas currently
impacted. Our limited understanding of marine ecosystem
responses to multifactorial physicochemical
climate drivers as well as our poor knowledge of the
potential of marine microalgae to adapt genetically
and phenotypically to the unprecedented pace of
current climate change are emphasized. The greatest
problems for human society will be caused by being
unprepared for significant range expansions or the
increase of algal biotoxin problems in currently
poorly monitored areas, thus calling for increased
vigilance in seafood-biotoxin and HAB monitoring
programs. Changes in phytoplankton communities
provide a sensitive early warning for climate-driven
perturbations to marine ecosystems.

/pdf/ocean-climate-change-phytoplankton-community-responses-and-3vq5zutr9a.pdf

Ocean climate change, phytoplankton community responses, and harmful algal blooms: a formidable predictive challenge

The public health, tourism, fisheries, and ecosystem impacts from harmful algal blooms (HABs) have all increased over the past few decades. This has led to heightened scientific and regulatory attention, and the development of many new technologies and approaches for research and management. This, in turn, is leading to significant paradigm shifts with regard to, e.g., our interpretation of the phytoplankton species concept (strain variation), the dogma of their apparent cosmopolitanism, the role of bacteria and zooplankton grazing in HABs, and our approaches to investigating the ecological and genetic basis for the production of toxins and allelochemicals. Increasingly, eutrophication and climate change are viewed and managed as multifactorial environmental stressors that will further challenge managers of coastal resources and those responsible for protecting human health. Here we review HAB science with an eye toward new concepts and approaches, emphasizing, where possible, the unexpected yet promising new directions that research has taken in this diverse field.

https://www.whoi.edu/fileserver.do?id=201484&pt=2&p=28251

Progress in understanding harmful algal blooms: paradigm shifts and new technologies for research, monitoring, and management.

. Four strains of the coccolithophore E. huxleyi (RCC1212, RCC1216, RCC1238, RCC1256) were grown in dilute batch culture at four CO2 levels ranging from ~200 μatm to ~1200 μatm. Growth rate, particulate organic carbon content, and particulate inorganic carbon content were measured, and organic and inorganic carbon production calculated. The four strains did not show a uniform response to carbonate chemistry changes in any of the analysed parameters and none of the four strains displayed a response pattern previously described for this species. We conclude that the sensitivity of different strains of E. huxleyi to acidification differs substantially and that this likely has a genetic basis. We propose that this can explain apparently contradictory results reported in the literature.

/pdf/strain-specific-responses-of-emiliania-huxleyi-to-changing-2u3qq9bz83.pdf

J. Ly

Papers

Strain-specific responses of Emiliania huxleyi to changing seawater carbonate chemistry

Effect of changing carbonate chemistry on calcification of Emiliania huxleyi