Climate change refugia in the terrestrial biosphere are areas where species are protected from global environmental change and arise from natural heterogeneity in landscapes and climate. Within the ...marine realm, ocean acidification, or the global decline in seawater pH, remains a pervasive threat to organisms and ecosystems. Natural variability in seawater carbon dioxide (CO2) chemistry, however, presents an opportunity to identify ocean acidification refugia (OAR) for marine species. Here, we review the literature to examine the impacts of variable CO2 chemistry on biological responses to ocean acidification and develop a framework of definitions and criteria that connects current OAR research to management goals. Under the concept of managing vulnerability, the most likely mechanisms by which OAR can mitigate ocean acidification impacts are by reducing exposure to harmful conditions or enhancing adaptive capacity. While local management options, such as OAR, show some promise, they present unique challenges, and reducing global anthropogenic CO2 emissions must remain a priority.
Ocean acidification refugia (OAR) may exist due to natural spatial and temporal variability in seawater carbon dioxide (CO2) across marine ecosystems. Based on a literature review of biological responses to variable CO2, we identify two types of refugia, those that reduce harmful exposures to ocean acidification and those that boost the adaptive capacity of marine organisms. The conditions that shape OAR must persist through time and may benefit from additional management actions.
Phenotypic plasticity is expected to facilitate the persistence of natural populations as global change progresses. The attributes of fluctuating environments that favor the evolution of plasticity ...have received extensive theoretical investigation, yet empirical validation of these findings is still in its infancy. Here, we combine high-resolution environmental data with a laboratory-based experiment to explore the influence of habitat pH fluctuation dynamics on the plasticity of gene expression in two populations of the Mediterranean mussel, Mytilus galloprovincialis. We linked differences in the magnitude and predictability of pH fluctuations in two habitats to population-specific gene expression profiles in ambient and stressful pH treatments. Our results demonstrate population-based differentiation in gene expression plasticity, whereby mussels native to a habitat exhibiting a large magnitude of pH fluctuations with low predictability display reduced phenotypic plasticity between experimentally imposed pH treatments. This work validates recent theoretical findings on evolution in fluctuating environments, suggesting that the predictability of fluctuating selection pressures may play a predominant role in shaping the phenotypic variation observed across natural populations.
In the coastal ocean, temporal fluctuations in pH vary dramatically across biogeographic ranges. How such spatial differences in pH variability regimes might shape ocean acidification resistance in ...marine species remains unknown. We assessed the pH sensitivity of the sea urchin Strongylocentrotus purpuratus in the context of ocean pH variability. Using unique male–female pairs, originating from three sites with similar mean pH but different variability and frequency of low pH (pHT ≤ 7.8) exposures, fertilization was tested across a range of pH (pHT 7.61–8.03) and sperm concentrations. High fertilization success was maintained at low pH via a slight right shift in the fertilization function across sperm concentration. This pH effect differed by site. Urchins from the site with the narrowest pH variability regime exhibited the greatest pH sensitivity. At this site, mechanistic fertilization dynamics models support a decrease in sperm–egg interaction rate with decreasing pH. The site differences in pH sensitivity build upon recent evidence of local pH adaptation in S. purpuratus and highlight the need to incorporate environmental variability in the study of global change biology.
How ocean pH variability may shape pH sensitivities of marine organisms was investigated for sea urchin fertilization. Of three coastal locations with similar mean pH, but different pH variability exposures, urchins from the site with the narrowest pH variability exposures exhibited a greater pH sensitivity in fertilization dynamics compared to urchins from the sites with wider pH exposures. These results indicate that coastal ocean pH variability may influence how this species will respond to pH changes associated with future ocean acidification.
A successful integrated ocean acidification (OA) observing network must include 1) scientists and technicians from a range of disciplines (from physics to chemistry to biology to technology ...development) and across the globe; 2) government, private, and intergovernmental support; 3) regional cohorts working together on regionally specific issues; 4) publicly accessible data from the open ocean to coastal to estuarine systems; 5) close integration with other networks focusing on related measurements or issues including the social and economic consequences of OA; and 6) observation-based informational products useful for decision making such as management of fisheries and aquaculture. The Global Ocean Acidification Observing Network (GOA-ON), a key player in this vision, seeks to expand and enhance geographic extent and availability of coastal and open ocean observing data to ultimately inform adaptive measures and policy action, especially in support of the United Nations 2030 Agenda for Sustainable Development. GOA-ON works to empower and support regional collaborative networks such as the Latin American Ocean Acidification Network, supports new scientists entering the field with training, mentorship, and equipment, refines approaches for tracking biological impacts, and stimulates development of lower-cost methodology and technologies allowing for wider participation of scientists. GOA-ON seeks to collaborate with and complement work done by other observing networks such as those focused on carbon flux into the ocean, tracking of carbon and oxygen in the ocean, observing biological diversity, and determining short- and long-term variability in these and other ocean parameters through space and time.
The Southern Ocean, a region that will be an ocean acidification hotspot in the near future, is home to a uniquely adapted fauna that includes a diversity of lightly-calcified invertebrates. We ...exposed the larvae of the echinoid Sterechinus neumayeri to environmental levels of CO(2) in McMurdo Sound (control: 410 µatm, Ω = 1.35) and mildly elevated pCO(2) levels, both near the level of the aragonite saturation horizon (510 µatm pCO(2), Ω = 1.12), and to under-saturating conditions (730 µatm, Ω = 0.82). Early embryological development was normal under these conditions with the exception of the hatching process, which was slightly delayed. Appearance of the initial calcium carbonate (CaCO(3)) spicule nuclei among the primary mesenchyme cells of the gastrulae was synchronous between control and elevated pCO(2) treatments. However, by prism (7 days after the initial appearance of the spicule nucleus), elongating arm rod spicules were already significantly shorter in the highest CO(2) treatment. Unfed larvae in the 730 µatm pCO(2) treatment remained significantly smaller than unfed control larvae at days 15-30, and larvae in the 510 µatm treatment were significantly smaller at day 20. At day 30, the arm lengths were more differentiated between 730 µatm and control CO(2) treatments than were body lengths as components of total length. Arm length is the most plastic morphological aspect of the echinopluteus, and appears to exhibit the greatest response to high pCO(2)/low pH/low carbonate, even in the absence of food. Thus, while the effects of elevated pCO(2) representative of near future climate scenarios are proportionally minor on these early developmental stages, the longer term effects on these long-lived invertebrates is still unknown.
Predicting the potential for species adaption to climate change is challenged by the need to identify the physiological mechanisms that underpin species vulnerability. Here, we investigated the ...sensitivity to ocean acidification in marine mussels during early development, and specifically the trochophore stage. Using RNA and DNA sequencing and in situ RNA hybridization, we identified developmental processes associated with abnormal development and rapid adaptation to low pH. Trochophores exposed to low pH seawater exhibited 43 differentially expressed genes. Gene annotation and in situ hybridization of differentially expressed genes point to pH sensitivity of (1) shell field development and (2) cellular stress response. Five genes within these two processes exhibited shifts in allele frequencies indicative of a potential for rapid adaptation. This case study contributes direct evidence that protecting species’ existing genetic diversity is a critical management action to facilitate species resilience to climate change.
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•Marine mussel larval development and genetic adaptation in low pH seawater•RNA and DNA responses reveal impacts on shell field development and cell stress•Five genes exhibited both physiological sensitivity and long-term adaptive potential•Conserving standing genetic variation could bolster resilience to global change
Biological sciences; Evolutionary biology; Developmental biology; Omics
Abstract
Understanding how declining seawater pH caused by anthropogenic carbon emissions, or oceanacidification, impacts Southern Ocean biota is limited by a paucity of pH time-series. Here,we ...present the first high-frequency in-situ pH time-series in near-shore Antarctica fromspring to winter under annual sea ice. Observations from autonomous pH sensors revealed aseasonal increase of 0.3 pH units. The summer season was marked by an increase in temporalpH variability relative to spring and early winter, matching coastal pH variability observedat lower latitudes. Using our data, simulations of ocean acidification show a future periodof deleterious wintertime pH levels potentially expanding to 7–11 months annually by 2100.Given the presence of (sub)seasonal pH variability, Antarctica marine species have anexisting physiological tolerance of temporal pH change that may influence adaptation tofuture acidification. Yet, pH-induced ecosystem changes remain difficult to characterize inthe absence of sufficient physiological data on present-day tolerances. It is thereforeessential to incorporate natural and projected temporal pH variability in the design ofexperiments intended to study ocean acidification biology.
TAKING THE PULSE OF MARINE ECOSYSTEMS HOFMANN, GRETCHEN E.; BLANCHETTE, CAROL A.; RIVEST, EMILY B. ...
Oceanography (Washington, D.C.),
09/2013, Letnik:
26, Številka:
3
Journal Article
Recenzirano
Odprti dostop
Research programs that co-locate environmental sensors with "biology" can enable the linking of environmental data with changes in biological or ecological processes. The coastal and marine Long Term ...Ecological Research (LTER) programs use this strategy, measuring parameters such as air and sea temperature, wave and storm energy, and seawater chemistry along with biological responses to them. This investment in technology has proven to be valuable and a major scientific asset for understanding how climate change, and environmental change in general, might alter marine populations and communities. Such a strategy can also aid in studies of global change biology of critical species, helping to place laboratory experiments and predictions of response in a broader environmental context. This coupling of long-term physical and biological observations has already detected fingerprints of change in sites such as the Palmer LTER situated on the western Antarctic Peninsula. In addition, new autonomous pH sensors recently deployed at two marine LTERs—Santa Barbara Coastal and Moorea Coral Reef—are generating long-term data sets that highlight the responses of their marine communities to rapidly changing ocean conditions.
Eastern boundary current systems (EBCSs) experience dynamic fluctuations in seawater pH due to coastal upwelling and primary production. The lack of high-resolution pH observations in EBCSs limits ...the ability to relate field pH exposures to performance of coastal marine species under future ocean change (acidification, warming). This 3-yr study describes spatio-temporal pH variability across the northern Channel Islands, along a persistent temperature gradient (1–4°C) within the eastern boundary California Current System. pH and Conductivity, Temperature, Depth, and Oxygen sensors were deployed on island piers in eelgrass and kelp habitat and on a subtidal mooring. Due to event-scale primary production, the temperature gradient across the islands did not manifest in a pH gradient. We resolved spatial pH variability on diel (ΔpHT 0.05–0.2: photosynthesis), event-scale (ΔpHT <0.1–0.2: upwelling, phytoplankton blooms, wind relaxation), and seasonal (ΔpHT 0.06: warming) time frames. In the kelp forest, summer mean pHT (8.01–8.02) and magnitude of diel pHT cycles (ΔpHT 0.12–0.10) were comparable year-to-year, despite 2.1°C warming from 2012 to 2014. Compared to nearby mainland sites, the northern Channel Islands experienced few low pH events. The majority of pHT observations were > 7.9. The lowest pH observations (> 1 SD below mean pHT) occurred under either warm (respiration during warm nights) or cold (advection of upwelled water) temperatures. We emphasize the importance of incorporating site-specific environmental variability in studies of ocean change biology, particularly in the design of multistressor experiments.
Research assessing the biological impacts of global ocean change often requires a burdensome characterization of seawater carbonate chemistry. For laboratory-based ocean acidification research, this ...impedes the scope of experimental design. Honeywell Durafet® III pH electrodes provide precise and continuous seawater pH measurements. In addition to use in oceanographic sensor packages, Durafets can also be used in the laboratory to track and control seawater treatments via Honeywell Universal Dual Analyzers (UDA). Here we provide performance data, instructions, and step-by-step recommendations for use of multiple UDA-Durafets. Durafet pH measurements were within ± 0.005 units pHT of spectrophotometric measurements and agreement among eight Durafets was better than ± 0.005 units pHT. These results indicate equal performance to Durafets in oceanographic sensor packages, but methods for calibration and quality control differ. Use of UDA-Durafets vastly improves time-course documentation of experimental conditions and reduces person-hours dedicated to this activity. Due to the versatility of integrating Durafets in laboratory seawater systems, this technology opens the door to advance the scale of questions that the ocean acidification research community aims to address.
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