Archive Page 232

Species turnover underpins the effect of elevated CO2 on biofilm communities through early succession

Published 22 July 2021 Science Closed
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Highlights

  • High CO2 conditions profoundly affected biofilm community composition
  • Species turnover explained differences in community composition
  • Biofilm communities were more homogeneous under high CO2 conditions
  • Toxin producing and turf-forming algae were enriched under high CO2 conditions

Abstract

Biofilms harbour a wealth of microbial diversity and fulfil key functions in coastal marine ecosystems. Elevated carbon dioxide (CO2) conditions affect the structure and function of biofilm communities, yet the ecological patterns that underpin these effects remain unknown. We used high-throughput sequencing of the 16S and 18S rRNA genes to investigate the effect of elevated CO2 on the early successional stages of prokaryotic and eukaryotic biofilms at a CO2 seep system off Shikine Island, Japan. Elevated CO2 profoundly affected biofilm community composition throughout the early stages of succession, leading to greater compositional homogeneity between replicates and the proliferation of the potentially harmful algae Prymnesium sp. and Biddulphia biddulphiana. Species turnover was the main driver of differences between communities in reference and high CO2 conditions, rather than differences in richness or evenness. Our study indicates that species turnover is the primary ecological pattern that underpins the effect of elevated CO2 on both prokaryotic and eukaryotic components of biofilm communities, indicating that elevated CO2 conditions represent a distinct niche selecting for a distinct cohort of organisms without the loss of species richness.

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Simplification, not “tropicalization”, of temperate marine ecosystems under ocean warming and acidification

Published 22 July 2021 Science Closed
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Ocean warming is altering the biogeographical distribution of marine organisms. In the tropics, rising sea surface temperatures are restructuring coral reef communities with sensitive species being lost. At the biogeographical divide between temperate and tropical communities, warming is causing macroalgal forest loss and the spread of tropical corals, fishes and other species, termed “tropicalization”. A lack of field research into the combined effects of warming and ocean acidification means there is a gap in our ability to understand and plan for changes in coastal ecosystems. Here, we focus on the tropicalization trajectory of temperate marine ecosystems becoming coral-dominated systems. We conducted field surveys and in situ transplants at natural analogues for present and future conditions under (i) ocean warming and (ii) both ocean warming and acidification at a transition zone between kelp and coral-dominated ecosystems. We show that increased herbivory by warm-water fishes exacerbates kelp forest loss and that ocean acidification negates any benefits of warming for range extending tropical corals growth and physiology at temperate latitudes. Our data show that, as the combined effects of ocean acidification and warming ratchet up, marine coastal ecosystems lose kelp forests but do not gain scleractinian corals. Ocean acidification plus warming leads to overall habitat loss and a shift to simple turf-dominated ecosystems, rather than the complex coral-dominated tropicalized systems often seen with warming alone. Simplification of marine habitats by increased CO2 levels cascades through the ecosystem and could have severe consequences for the provision of goods and services.

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Climate mitigation averts corrosive acidification in the upper ocean

Published 22 July 2021 Science Closed
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The invasion of anthropogenic carbon into the global ocean poses an existential threat to calcifying marine organisms1–4. Observations indicate that conditions corrosive to aragonite shells, unprecedented in the surface ocean, are already occurring in mesoscale upwelling features of the North Pacific2,5,6 and Southern Ocean7, and modeling experiments indicate that large volumes of the global ocean8 including the polar ocean’s surface might become corrosive to aragonite by 20304,9–13. Such changes are expected to compress important marine habitats, but the pathways by which habitat compression manifests over global scales, and their sensitivity to mitigation, remain unexplored. Using a suite of large ensemble projections from an Earth system model14,15, we assess the effectiveness of climate mitigation for averting habitat loss at the ecologically-critical horizon of the base of the ocean’s euphotic zone. We find that without mitigation, 40-42% of this sensitive horizon experiences conditions corrosive to aragonite by 2100, with moderate mitigation this reduces to 16-19%, and with aggressive mitigation to 6-7%. Mitigation has a stronger effect on the eastern relative to western domains of the northern extratropical ocean with some of the greatest benefits in the ocean’s most productive Large Marine Ecosystems, including the California Current and Gulf of Alaska. This work reveals the significant impact that mitigation efforts compatible with the Paris Agreement target of 1.5°C could have upon preserving marine habitats that are vulnerable to ocean acidification.

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Low-oxygen waters off Washington, Oregon coasts risk becoming large ‘dead zones’

Published 22 July 2021 Web sites and blogs Closed
Low-oxygen waters off Washington, Oregon coasts risk becoming large 'dead zones'

Oceanic measurements collected during a scientific cruise on NOAA Ship Ronald H. Brown last week confirmed that a large area of poorly oxygenated water is growing off the coast of Washington and Oregon. 

Oxygen-depleted bottom waters occur seasonally along the continental shelf of Washington and Oregon when strong winds blowing along the coast in spring and summer trigger upwellings that bring deep, cold, nutrient-rich water to the surface. These waters fuel blooms of plankton that feed small animals like krill, which are food for many marine creatures. When these blooms die off, they sink to the bottom, where their decomposition consumes oxygen, leaving less for organisms such as crabs and bottom-dwelling fish.

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Earliest onset in 35 years

“Low dissolved oxygen levels have become the norm ion the Pacific Northwest coast, but this event started much earlier than we’ve seen in our records,” said Oregon State University Professor Francis Chan, director of the NOAA cooperative institute CIMERS. “This is the earliest start to the upwelling season in 35 years.” Typically, hypoxic conditions don’t appear until  late June or early July, he said.  

This map shows the location of transect lines that are being sampled during the 2021 West Coast Ocean Acidification Cruise. Measurements taken in coastal Washington and Oregon waters confirm the presence of a large area of bottom water that has low dissolved oxygen levels. Credit: CICOES
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Ocean warming, acidification shift temperate coastal reefs into simpler ecosystems

Published 21 July 2021 Press releases Closed

The once common kelp forests and abalone fisheries of the Shikine Island in Japan have now vanished. Scientists from Japan identified that these temperate coastal marine ecosystems are transforming into much “simpler” ones, deprived of their biodiversity aesthetic values and complexity.

Ocean Warming, Acidification Shift Temperate Coastal Reefs into Simpler EcosystemsResearchers from the University of Tsukuba find that the combined effects of ocean warming and acidification in temperate marine ecosystems are resulting in a loss of kelp habitat and a shift to a simple turf-dominated ecosystem. Such changes will lead to a loss of the ecosystem services provided by productive macroalgal forests or tropicalized coral-dominated reefs. These results highlight the need for reductions in greenhouse gas emissions. Image Credit: University of Tsukuba.

Scientists from the University of Tsukuba along with their international collaborators investigated the combined effects of ocean warming and acidification on the temperate coastal marine ecosystems.

Coral reefs are synonymous with the tropical coastal seas. When the ocean temperatures cool in the direction of the poles, corals yield to kelp as the main habitat-forming species. This shift from coral to kelp can be seen evidently on the 2000 km coastline of Japan, where modifications to these ecosystems are ongoing.

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New insights from transcriptomic data reveal differential effects of CO2 acidification stress on photosynthesis of an endosymbiotic dinoflagellate in hospite

Published 21 July 2021 Science Closed
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Ocean acidification (OA) has both detrimental as well as beneficial effects on marine life; it negatively affects calcifiers while enhancing the productivity of photosynthetic organisms. To date, many studies have focused on the impacts of OA on calcification in reef-building corals, a process particularly susceptible to acidification. However, little is known about the effects of OA on their photosynthetic algal partners, with some studies suggesting potential benefits for symbiont productivity. Here, we investigated the transcriptomic response of the endosymbiont Symbiodinium microadriaticum (CCMP2467) in the Red Sea coral Stylophora pistillata subjected to different long-term (2 years) OA treatments (pH 8.0, 7.8, 7.4, 7.2). Transcriptomic analyses revealed that symbionts from corals under lower pH treatments responded to acidification by increasing the expression of genes related to photosynthesis and carbon-concentrating mechanisms. These processes were mostly up-regulated and associated metabolic pathways were significantly enriched, suggesting an overall positive effect of OA on the expression of photosynthesis-related genes. To test this conclusion on a physiological level, we analyzed the symbiont’s photochemical performance across treatments. However, in contrast to the beneficial effects suggested by the observed gene expression changes, we found significant impairment of photosynthesis with increasing pCO2. Collectively, our data suggest that over-expression of photosynthesis-related genes is not a beneficial effect of OA but rather an acclimation response of the holobiont to different water chemistries. Our study highlights the complex effects of ocean acidification on these symbiotic organisms and the role of the host in determining symbiont productivity and performance.

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Mechanisms driving decadal changes in the carbonate system of a coastal plain estuary

Published 21 July 2021 Science Closed
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Abstract

Understanding decadal changes in the coastal carbonate system is essential for predicting how the health of these waters responds to anthropogenic drivers, such as changing atmospheric conditions and riverine inputs. However, studies that quantify the relative impacts of these drivers are lacking. In this study, the primary drivers of decadal trends in the surface carbonate system, and the spatiotemporal variability in these trends, are identified for a large coastal plain estuary: the Chesapeake Bay. Experiments using a coupled three-dimensional hydrodynamic-biogeochemical model highlight that, over the past three decades, the changes in the surface carbonate system of Chesapeake Bay have strong seasonal and spatial variability. The greatest surface pH and aragonite saturation state (ΩAR) reductions have occurred in the summer in the middle (mesohaline) Bay: −0.24 and −0.9 per 30 years, respectively, with increases in atmospheric CO2 and reductions in nitrate loading both being primary drivers. Reductions in nitrate loading have a strong seasonal influence on the carbonate system, with the most pronounced decadal decreases in pH and ΩAR occurring during the summer when primary production is strongly dependent on nutrient availability. Increases in riverine total alkalinity and dissolved inorganic carbon have raised surface pH in the upper oligohaline Bay, while other drivers such as atmospheric warming and input of acidified ocean water through the Bay mouth have had comparatively minor impacts on the estuarine carbonate system. This work has significant implications for estuarine ecosystem services, which are typically most sensitive to surface acidification in the spring and summer seasons.

Plain Language Summary

Seawater pH, a measure of how acidic or basic water is, is a crucial water quality parameter influencing the growth and health of marine organisms, such as oysters, fishes and crabs. Decreasing pH, commonly referred to as acidification, is a severe environmental issue that has been exacerbated by human activities since the industrial revolution. In the open ocean, elevated atmospheric carbon dioxide is the key driver of acidification. However, in coastal environments the drivers are particularly complex due to changing human influences on land. In this study the primary drivers of acidification in the Chesapeake Bay over the past three decades are identified via the application of a three-dimensional ecosystem model. Increased atmospheric CO2 concentrations and decreased terrestrial nutrient inputs are two primary drivers causing nearly equal reductions in pH in surface waters of the Bay. The pH reductions resulting from decreased nutrient loads indicate that the system is reverting back to more natural conditions when human-induced nutrient inputs to the Bay were lower. As nutrient reduction efforts to improve coastal water quality continue in the future, controlling the emissions of anthropogenic CO2 globally becomes increasingly important for the shellfish industry and the ecosystem services it provides.

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Impact of anthropogenic pH perturbation on dimethyl sulfide cycling: a peek into the microbial black box

Published 21 July 2021 Science Closed
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The objective of this study was to assess experimentally the potential impact of anthropogenic pH perturbation (ApHP) on concentrations of dimethyl sulfide (DMS) and dimethylsulfoniopropionate (DMSP), as well as processes governing the microbial cycling of sulfur compounds. A summer planktonic community from surface waters of the Lower St. Lawrence Estuary was monitored in microcosms over 12 days under three pCO2 targets: 1 × pCO2 (775 µatm), 2 × pCO2 (1,850 µatm), and 3 × pCO2 (2,700 µatm). A mixed phytoplankton bloom comprised of diatoms and unidentified flagellates developed over the course of the experiment. The magnitude and timing of biomass buildup, measured by chlorophyll a concentration, changed in the 3 × pCO2 treatment, reaching about half the peak chlorophyll a concentration measured in the 1 × pCO2 treatment, with a 2-day lag. Doubling and tripling the pCO2 resulted in a 15% and 40% decline in average concentrations of DMS compared to the control. Results from 35S-DMSPd uptake assays indicated that neither concentrations nor microbial scavenging efficiency of dissolved DMSP was affected by increased pCO2. However, our results show a reduction of the mean microbial yield of DMS by 34% and 61% in the 2 × pCO2 and 3 × pCO2 treatments, respectively. DMS concentrations correlated positively with microbial yields of DMS (Spearman’s ρ = 0.65; P < 0.001), suggesting that the impact of ApHP on concentrations of DMS in diatom-dominated systems may be strongly linked with alterations of the microbial breakdown of dissolved DMSP. Findings from this study provide further empirical evidence of the sensitivity of the microbial DMSP switch under ApHP. Because even small modifications in microbial regulatory mechanisms of DMSP can elicit changes in atmospheric chemistry via dampened efflux of DMS, results from this study may contribute to a better comprehension of Earth’s future climate.

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SEA MATE Program reducing acid in oceans, CO2 in the atmosphere

Published 21 July 2021 Projects , Web sites and blogs Closed
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A team of researchers called SEA MATE, led by Stony Brook University professor Matthew Eisaman, is using electricity to remove acid from the ocean while also taking carbon dioxide from the atmosphere.

Continually increasing carbon dioxide concentrations in the atmosphere have already led to changes in the climate as well as the acidification of the oceans. This increased acidity of the oceans is analogous to a slow motion “spill” of acid, so just as oil spills need to be cleaned up, so do these acid spills.

Eisaman m
Matthew Eisaman, professor of Electrical and Computer Engineering.

The approach of SEA MATE (Safe Elevation of Alkalinity for the Mitigation of Acidification Through Electrochemistry) uses carbon-free electricity and electrochemistry to effectively pump this excess acid out of the ocean and then sells the acid for useful purposes. This acid removal restores the ocean chemistry such that the remaining ions in the ocean react with atmospheric carbon dioxide, safely locking it up for 10,000 – 200,000 years as oceanic bicarbonate. The net effect of SEA MATE is the reversal of ocean acidification along with the net removal of carbon dioxide from the atmosphere.

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Early deployments will likely partner with existing marine industries such as seawater desalination, aquaculture, maritime transport, and offshore wind. As an example, performing the SEA MATE process on the waste effluent from desalination plants would provide value to these plants by reducing their environmental impact, while also mitigating ocean acidification and decreasing the concentration of atmospheric carbon dioxide.

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UN Ocean Decade endorses several AOML collaborative initiatives

Published 21 July 2021 Program , Projects , Web sites and blogs Closed
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In 2017, the United Nations General Assembly proclaimed the time frame of 2021-2030 as the UN Decade of Ocean Science for Sustainable Development, also known as the “Ocean Decade,” to address the degradation of the ocean and encourage innovative science initiatives to better understand and ultimately reverse its declining health. 

Several collaborative initiatives featuring work by scientists at NOAA’s Atlantic Oceanographic Meteorological Laboratory (AOML) have recently been endorsed in the first Ocean Decade Actions announcement, made by the United Nations Intergovernmental Oceanographic Commission (IOC) of UNESCO in 2021. 

Scientists at AOML are collaborating with national and international partners and stakeholders to carry out research that supports the vision of the UN Ocean Decade through initiatives such as the Observing Air-Sea Interactions Strategy (OASIS), the Ocean Biomolecular Observing Network (OBON), the Global Ocean Biogeochemistry Array (GO-BGC), and the Ocean Acidification Research for Sustainability (OARS) program.

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Chapter one – Physiological impacts of ocean acidification on marine invertebrates

Published 20 July 2021 Science Closed
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Since the Industrial Revolution, the massive amount of anthropogenic carbon dioxide (CO2) generated has elevated the atmospheric CO2 concentration. About one-fourth to one-third of the anthropogenic CO2 has been absorbed by the ocean, which leads to reductions in both oceanic pH and carbonate ion concentrations, a process known as “ocean acidification” (OA). Theoretically, OA will pose a great threat to a variety of marine invertebrates by influencing the skeletal formation and the chemical properties of habitats. Since invertebrates play a significant role in the marine ecosystem and many marine invertebrates are economically important aquaculture species, the effects of OA on marine invertebrates have been a hotspot for research in recent years. In this chapter, the current knowledge of the physiological influences of OA on marine invertebrates, including gametic traits, fertilization success, embryonic development, biomineralization, metabolism, growth, and immune responses, was summarized. In addition, the potential underlying affecting mechanisms were discussed. The authors hope that the contents of this chapter provide some basic information and guidance for readers who are interested in this area and plan to carry out future studies on this topic.

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Chapter two – Physiological impacts of ocean acidification on marine vertebrates

Published 20 July 2021 Science Closed
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Human activities and global climate change give rise to the increasing concentration of carbon dioxide (CO2) in the atmosphere, which is subsequently absorbed by the ocean surface, leading to ocean acidification (OA). At present, the global OA driven by CO2 is becoming more and more serious, which poses a great threat to marine ecosystems. A lot of investigations have shown that OA has disrupted various trophic levels of the food chain in marine ecosystems, including marine invertebrates and vertebrates. These impacts are harmful to the health and stability of marine ecosystems. As a typical representative of marine vertebrates, marine teleosts are suffering from the environmental stresses caused by OA, but our understanding of the impacts of OA on these species is not profound. This chapter systematically summarizes the effects of OA on marine teleosts, including acid–base and ion regulation, fertilization, embryonic development, growth, metabolism, reproduction, behaviors, and many other aspects. By analyzing the relevant research progress, we expect to deeply understand the responses of marine vertebrates such as teleosts to OA and the related underlying mechanisms, which will be conducive to effectively avoiding the threat of global climate change and providing theoretical references for formulating effective coping strategies against OA.

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Chapter three – Behavioral impacts of ocean acidification on marine animals

Published 20 July 2021 Science Closed
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Behavioral modification is the distinct response exhibited by marine animals to stressors. Exposure to oceanic environmental changes can alter the behaviors of aquatic animals, such as foraging, antipredation, habitat selection, and social hierarchy. Ocean acidification (OA) can alter the animal behaviors of a single species and thereby affect the structure and function of marine populations, communities, and ecosystems. Recently, the effects of OA on the behavioral responses of marine animals have received much attention. Considering the essential ecological functions and fishery value of marine living resources, we need to remain vigilant about the subsequent risk of OA. Here, we provide a systematic review including some classical case studies to highlight the effects of CO2-driven OA on the most common behaviors studied in marine animals and synthesize the current understanding of how OA may impact marine animal behaviors.

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Chapter four – Potential mechanisms underpinning the impacts of ocean acidification on marine animals

Published 20 July 2021 Science Closed
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Oceanic uptake of atmospheric CO2 is reducing seawater pH and shifting seawater carbonate chemistry—a process known as ocean acidification (OA). Studies have demonstrated that OA would affect a broad range of biological processes and physiological functions of marine organisms, including fertilization, larval development, calcification, metabolism, immune responses, growth, and behavior. However, there have been fewer detailed investigations of OA’s impacts on the physiological processes of marine organisms at the biochemical and cellular levels; therefore the mechanisms responsible for these effects remain largely unclear. The present chapter reviews the potential mechanisms underpinning the impacts of OA on marine animals, which include the following: (1) disturbance of acid–base homeostasis and energy reallocation by OA; (2) alteration in the normal function of neurotransmitters due to OA; (3) interference with the transduction of neural signals by OA; and (4) OA’s influence on the expression patterns of genes and proteins involved in key biological processes.

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Chapter five – Interactive effects of ocean acidification and other environmental factors on marine organisms

Published 20 July 2021 Science Closed
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In recent decades, the marine environment has been seriously affected by various anthropogenic activities (e.g., deforestation, fossil fuel combustion, and disordered discharges of pollutants). As a consequence, a range of changes in seawater environmental factors have taken place in oceans around the world, including increased temperature, reduced pH and dissolved oxygen, salinity fluctuation, and many other anomalous alterations in environmental factors, and these changes have aroused concerns from scientists. It has been widely reported that these changes in environmental factors would impact marine organisms severely. Meanwhile, it is worth noting that the environmental stressors mentioned above are rarely occurring independently in nature. Thus marine organisms are usually threatened by many different environmental stressors, and there would be complex and unpredicted interactions among the stressors. Generally, the interactive effects varied among additive (total effect equal to the sum of individual effects), synergistic (total effect greater than the sum of individual effects), or antagonistic (total effect less than the sum of individual effects), depending on the species and life stages of the studied organism, and the nature of the stressors themselves. It is necessary to figure out the interactive effects among various environmental stressors on specific marine organisms to accurately predict their physiological states and population dynamics under future climate scenarios. Therefore in this chapter, we summarize the related experiments in the last 20 years to discuss the interactive effects of ocean acidification (OA) combined with four other typical environmental stressors, namely ocean warming, hypoxia, salinity fluctuation, and heavy metal pollution, on marine organisms according to previously published studies. The authors hope that the contents of this chapter provide some basic information about the interactive effects of OA and the other four environmental factors for readers who are interested in this subject area.

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Chapter six – A brief summary of what we know and what we do not know about the impacts of ocean acidification on marine animals

Published 20 July 2021 Science Closed
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In the past decades, the impacts of ocean acidification (OA) on marine animals have gained much attention. To date, numerous works in the literature have shown that OA can affect a variety of biological processes of marine animals, and our knowledge about its effects on marine organisms is mainly focused on the following aspects: (1) fertilization and early development; (2) biomineralization, metabolism, and growth; and (3) immunity and behaviors. However, there are still some limitations that currently exist in research on OA, which include (1) performing experiments with “constant acidification” rather than natural pH fluctuations that may not fully reflect their future true living conditions; (2) using pCO2 levels that were predicted to be reached in a hundred years in the future for experiments with relatively short exposure times, thus overlooking marine organisms’ potential for genetic adaptation or acclimation to the acidified seawater; (3) large amounts of experiments examining OA’s physiological impacts while leaving the potential affecting mechanisms largely unstudied; and (4) a lack of experiments investigating indirect effects of OA on marine organisms and the whole ecosystem. After providing a summary of the current knowledge of OA’s impacts on marine animals, this review aims to highlight potential directions for future studies.

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Decadal dynamics of the CO2 system and associated ocean acidification in coastal ecosystems of the North East Atlantic Ocean

Published 19 July 2021 Science Closed
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Weekly and bi-monthly carbonate system parameters and ancillary data were collected from 2008 to 2020 in three coastal ecosystems of the southern Western English Channel (sWEC) (SOMLIT-pier and SOMLIT-offshore) and Bay of Brest (SOMLIT-Brest) located in the North East Atlantic Ocean. The main drivers of seasonal and interannual partial pressure of CO2 (pCO2) and dissolved inorganic carbon (DIC) variabilities were the net ecosystem production (NEP) and thermodynamics. Differences were observed between stations, with a higher biological influence on pCO2 and DIC in the near-shore ecosystems, driven by both benthic and pelagic communities. The impact of riverine inputs on DIC dynamics was more pronounced at SOMLIT-Brest (7%) than at SOMLIT-pier (3%) and SOMLIT-offshore (<1%). These three ecosystems acted as a weak source of CO2 to the atmosphere of 0.18 ± 0.10, 0.11 ± 0.12, and 0.39 ± 0.08 mol m–2 year–1, respectively. Interannually, air-sea CO2 fluxes (FCO2) variability was low at SOMLIT-offshore and SOMLIT-pier, whereas SOMLIT-Brest occasionally switched to weak annual sinks of atmospheric CO2, driven by enhanced spring NEP compared to annual means. Over the 2008–2018 period, monthly total alkalinity (TA) and DIC anomalies were characterized by significant positive trends (p-values < 0.001), from 0.49 ± 0.20 to 2.21 ± 0.39 μmol kg−1 year−1 for TA, and from 1.93 ± 0.28 to 2.98 ± 0.39 μmol kg–1 year–1 for DIC. These trends were associated with significant increases of calculated seawater pCO2, ranging from +2.95 ± 1.04 to 3.52 ± 0.47 μatm year–1, and strong reductions of calculated pHin situ, with a mean pHin situ decrease of 0.0028 year–1. This ocean acidification (OA) was driven by atmospheric CO2 forcing (57–66%), Sea surface temperature (SST) increase (31–37%), and changes in salinity (2–5%). Additional pHin situ data extended these observed trends to the 2008–2020 period and indicated an acceleration of OA, reflected by a mean pHin situ decrease of 0.0046 year–1 in the sWEC for that period. Further observations over the 1998–2020 period revealed that the climatic indices North Atlantic Oscillation (NAO) and Atlantic Multidecadal Variability (AMV) were linked to trends of SST, with cooling during 1998–2010 and warming during 2010–2020, which might have impacted OA trends at our coastal stations. These results suggested large temporal variability of OA in coastal ecosystems of the sWEC and underlined the necessity to maintain high-resolution and long-term observations of carbonate parameters in coastal ecosystems.

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Scaling the effects of ocean acidification on coral growth and coral–coral competition on coral community recovery

Published 19 July 2021 Science Closed
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Ocean acidification (OA) is negatively affecting calcification in a wide variety of marine organisms. These effects are acute for many tropical scleractinian corals under short-term experimental conditions, but it is unclear how these effects interact with ecological processes, such as competition for space, to impact coral communities over multiple years. This study sought to test the use of individual-based models (IBMs) as a tool to scale up the effects of OA recorded in short-term studies to community-scale impacts, combining data from field surveys and mesocosm experiments to parameterize an IBM of coral community recovery on the fore reef of Moorea, French Polynesia. Focusing on the dominant coral genera from the fore reef, Pocillopora, Acropora, Montipora and Porites, model efficacy first was evaluated through the comparison of simulated and empirical dynamics from 2010–2016, when the reef was recovering from sequential acute disturbances (a crown-of-thorns seastar outbreak followed by a cyclone) that reduced coral cover to ~0% by 2010. The model then was used to evaluate how the effects of OA (1,100–1,200 µatm pCO2) on coral growth and competition among corals affected recovery rates (as assessed by changes in % cover y−1) of each coral population between 2010–2016. The model indicated that recovery rates for the fore reef community was halved by OA over 7 years, with cover increasing at 11% y−1 under ambient conditions and 4.8% y−1 under OA conditions. However, when OA was implemented to affect coral growth and not competition among corals, coral community recovery increased to 7.2% y−1, highlighting mechanisms other than growth suppression (i.e., competition), through which OA can impact recovery. Our study reveals the potential for IBMs to assess the impacts of OA on coral communities at temporal and spatial scales beyond the capabilities of experimental studies, but this potential will not be realized unless empirical analyses address a wider variety of response variables representing ecological, physiological and functional domains.

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Discrete carbonate system parameter measurements in Middle Tampa Bay, Florida and the Eastern Gulf of Mexico, USA

Published 19 July 2021 Science Closed
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This dataset contains carbonate system data collected by scientists from the U.S. Geological Survey (USGS) St. Petersburg Coastal and Marine Science Center to investigate the effects of carbon cycling, coastal and ocean acidification on the Tampa Bay estuary located in west central Florida and eastern Gulf of Mexico. Discrete seawater samples were collected periodically (every few weeks to months) at repeat monitoring locations. Water samples were analyzed by the USGS Carbon Analytical Laboratory in St. Petersburg Florida. This dataset contains time series measurements of carbonate system parameters including: water temperature (Celsius, C), salinity, dissolved oxygen (milligrams/L), total alkalinity (TA, micromoles/kg), dissolved inorganic carbon (DIC, micromoles/kg), pHT (pH on the total scale), nitrate + nitrite (NO3+NO2, micromoles/L), nitrite (NO2, micromoles/L), silicate (SIL, micromoles/L), ammonium (NH4, micromoles/L) and phosphate (PO4, micromoles/L).

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Morphological response accompanying size reduction of belemnites during an Early Jurassic hyperthermal event modulated by life history

Published 19 July 2021 Science Closed
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One of the most common responses of marine ectotherms to rapid warming is a reduction in body size, but the underlying reasons are unclear. Body size reductions have been documented alongside rapid warming events in the fossil record, such as across the Pliensbachian-Toarcian boundary (PToB) event (~ 183 Mya). As individuals grow, parallel changes in morphology can indicate details of their ecological response to environmental crises, such as changes in resource acquisition, which may anticipate future climate impacts. Here we show that the morphological growth of a marine predator belemnite species (extinct coleoid cephalopods) changed significantly over the PToB warming event. Increasing robustness at different ontogenetic stages likely results from indirect consequences of warming, like resource scarcity or hypercalcification, pointing toward varying ecological tolerances among species. The results of this study stress the importance of taking life history into account as well as phylogeny when studying impacts of environmental stressors on marine organisms.

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