Archive for January, 2021

Research reveals genetic response of ocean warming and acidification in American lobster

Fisherman holding a lobster

A team of researchers from the University of Maine Darling Marine Center in Walpole, Bigelow Laboratory for Ocean Sciences in East Boothbay and Maine Department of Marine Resources in West Boothbay Harbor recently published their research on the effects of ocean warming and acidification on gene expression in the earliest life stages of the American lobster.

The work was published in the scientific journal Ecology and Evolution with collaborators from the University of Prince Edward Island and Dalhousie University in Canada.

Leading the study was recent UMaine graduate student Maura Niemisto, who received her master’s degree in marine science. Co-authors on the journal article were her advisers Richard Wahle, research professor in UMaine’s School of Marine Sciences and director of the Lobster Institute, and David Fields, senior research scientist at Bigelow Laboratory for Ocean Sciences. 

Continue reading ‘Research reveals genetic response of ocean warming and acidification in American lobster’

American lobster postlarvae alter gene regulation in response to ocean warming and acidification

Anthropogenic carbon emissions released into the atmosphere is driving rapid, concurrent increases in temperature and acidity across the world’s oceans. Disentangling the interactive effects of warming and acidification on vulnerable life stages is important to our understanding of responses of marine species to climate change. This study evaluates the interactive effects of these stressors on the acute response of gene expression of postlarval American lobster (Homarus americanus), a species whose geographic range is warming and acidifying faster than most of the world’s oceans. In the context of our experiment, we found two especially noteworthy results: First, although physiological end points have consistently been shown to be more responsive to warming in similar experimental designs, our study found gene regulation to be considerably more responsive to elevated pCO2. Furthermore, the combined effect of both stressors on gene regulation was significantly greater than either stressor alone. Using a full factorial experimental design, lobsters were raised in control and elevated pCO2 concentrations (400 ppm and 1,200 ppm) and temperatures (16°C and 19°C). A transcriptome was assembled from an identified 414,517 unique transcripts. Overall, 1,108 transcripts were differentially expressed across treatments, several of which were related to stress response and shell formation. When temperature alone was elevated (19°C), larvae downregulated genes related to cuticle development; when pCO2 alone was elevated (1,200 ppm), larvae upregulated chitinase as well as genes related to stress response and immune function. The joint effects of end‐century stressors (19°C, 1,200 ppm) resulted in the upregulation of those same genes, as well as cellulase, the downregulation of calcified cuticle proteins, and a greater upregulation of genes related to immune response and function. These results indicate that changes in gene expression in larval lobster provide a mechanism to respond to stressors resulting from a rapidly changing environment.

Continue reading ‘American lobster postlarvae alter gene regulation in response to ocean warming and acidification’

Impacts of hypoxic events surpass those of future ocean warming and acidification

Over the past decades, three major challenges to marine life have emerged as a consequence of anthropogenic emissions: ocean warming, acidification and oxygen loss. While most experimental research has targeted the first two stressors, the last remains comparatively neglected. Here, we implemented sequential hierarchical mixed-model meta-analyses (721 control–treatment comparisons) to compare the impacts of oxygen conditions associated with the current and continuously intensifying hypoxic events (1–3.5 O2 mg l−1) with those experimentally yielded by ocean warming (+4 °C) and acidification (−0.4 units) conditions on the basis of IPCC projections (RCP 8.5) for 2100. In contrast to warming and acidification, hypoxic events elicited consistent negative effects relative to control biological performance—survival (–33%), abundance (–65%), development (–51%), metabolism (–33%), growth (–24%) and reproduction (–39%)—across the taxonomic groups (mollusks, crustaceans and fish), ontogenetic stages and climate regions studied. Our findings call for a refocus of global change experimental studies, integrating oxygen concentration drivers as a key factor of ocean change. Given potential combined effects, multistressor designs including gradual and extreme changes are further warranted to fully disclose the future impacts of ocean oxygen loss, warming and acidification.

Continue reading ‘Impacts of hypoxic events surpass those of future ocean warming and acidification’

Effect of climate change on endocrine regulation of fish reproduction

Climate change is a serious concern for aquatic environment which alters physical and chemical properties of the water causing negative impacts on the aquatic organisms including fish. Temperature alteration, ocean acidification, and hypoxia are the major factors associated with climate change, which affects the endocrine regulation of fish reproduction profoundly. Fish being poikilothermic animals, the change in environmental temperature directly affects their body temperature. Seasonal change in temperature has either fastened the spawning process or delayed the process depending upon the species and their spawning window. Ocean acidification and hypoxia had caused threat to larval survival by impairing larval behavior and sensory capacity. Often climate change shows extreme effect of the demography of fishes by leading to a non-spawning season in some species. Depending upon species, geographic location, and spawning ground, exogenous factors possess significant threat on fish reproduction. The present chapter will provide baseline information on effect of different factors of climate change such as temperature, ocean acidification, and hypoxia on fish reproduction and early ontogenesis phase of fish.

Continue reading ‘Effect of climate change on endocrine regulation of fish reproduction’

Forecasting impacts of ocean acidification on marine communities: utilising volcanic CO2 vents as natural laboratories

Oceans have absorbed approximately 30% of anthropogenic CO2 emissions, causing a phenomenon known as ‘ocean acidification’. With surface ocean pH changing at a rapid pace, continued uptake of CO2 is expected to decrease ocean pH by 0.3 pH units as early as 2081, accompanied by a decrease in the saturation of calcium carbonate minerals needed to produce skeletons and shells (RCP 8.5 scenario, IPCC 2019).

Continue reading ‘Forecasting impacts of ocean acidification on marine communities: utilising volcanic CO2 vents as natural laboratories’

One-two punch against corals: how stress factors interact

A new study in the prestigious journal Science Advances shows that stress from rising water temperatures reduces ability of corals to adapt to ocean acidification.

About a quarter of the carbon emissions driving global warming are absorbed by the oceans, leading to lower pH values in the water and making it more acidic. Global warming is also causing water temperature in the oceans to rise, which leads to the bleaching of coral reefs worldwide. Now, a new study reveals that increased CO2 levels in the water and ocean warming can interact to threaten reef-building corals.

The international team of authors, led by the University of California, included Professor Hildegard Westphal and Dr. Claire Reymond from the Leibniz Centre for Tropical Marine Research (ZMT), as well as Professor Justin Ries, a former fellow of the Hanse-Wissenschaftskolleg and visiting scientist at the ZMT. Furthermore, researchers from the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI) in Bremerhaven and the Max Planck Institute for Marine Microbiology in Bremen were involved in the study.

Continue reading ‘One-two punch against corals: how stress factors interact’

Study demonstrates reductions in CO² could boost the recovery of marine life

World-leading experts in ocean acidification and warming monitored the effect differing ocean acidification had on different forms of algae

Making meaningful reductions in CO² emissions could help marine life damaged by increasingly acidified oceans to recover, according to new research.

An international team of scientists – world-leading experts in ocean acidification and warming from the University of Plymouth and the Shimoda Marine Research Center at the University of Tsukuba – placed a series of artificial tiles on the ocean floor off the coast of Japan.

Continue reading ‘Study demonstrates reductions in CO² could boost the recovery of marine life’

Interrelation of quality parameters of surface waters in five tidewater glacier coves of King George Island, Antarctica

Highlights

  • Repeated investigation in unprecedented proximity of 5 glacial fronts in Antarctica
  • Analysis of physical, chemical and biological water quality parameter interrelations
  • Correlations found between glacial meltwater and physicochemical parameter shifts
  • pH values shown rising with glacial meltwater presence
  • Varied biological parameter trends dependent on the distance from the glacial front

Abstract

For further understanding of glacial meltwater’s (GMW) impacts on marine environments, five coves adjacent to diverse glaciers of King George Island, Antarctica were investigated through surface measurements of water quality parameters. Measurements were conducted 49 times during January, February and March of 2019, with sampling performed in unprecedently close proximity to glacial fronts (< 50 m distance from glacier termini in each cove) to create a unique dataset. Four out of five of the coves were inspected through vertical profiling to show water-column stratification. The findings showed synchronized GMW influence causing decreases of salinity, temperature, and dissolved organic matter contents, combined with increased pH, turbidity, and dissolved oxygen values. GMW presence was most correlated with dissolved organic matter content (93% of the cases >0.5 correlation noted with either turbidity or salinity) and least correlated with water temperature (from 22% to 77% of the cases with >0.5 correlation, dependent on the cove). In contrast to previous studies, the pH values of seawater infused with GMW were higher than those of the surrounding water. GMW was shown to stay in the boundary surface layer of the water column. Phytoplankton pigment quantities depending on the localization, time and distance from the glacial termini presented varied response to GMW (positive, negative or ambivalent with hotspots of simultaneous high GMW and phytoplankton quantities). The positive response to glacial water input was more often noted in measurements of phycoerythrin (from 0 to 80% of the cases depending on the cove) rather than chlorophyll A (from 0 to 25%) and maximum quantities of both biological pigments were found at a depth of approximately 5-10 m.

Continue reading ‘Interrelation of quality parameters of surface waters in five tidewater glacier coves of King George Island, Antarctica’

Long-term thermal acclimation drives adaptive physiological adjustments of a marine gastropod to reduce sensitivity to climate change

Highlights

  • The effects of thermal history on thermal threshold and physiology were assessed.
  • Gastropods acclimated to warmer environments had higher thermal threshold (CTmax).
  • Warm-acclimated gastropods were metabolically less active than cool-acclimated ones.
  • Energy conservation appeared to be a strategy for thermal acclimation.
  • Long-term thermal acclimation may allow marine organisms to adjust to climate change.

Abstract

Ocean warming is predicted to challenge the persistence of a variety of marine organisms, especially when combined with ocean acidification. Whilst temperature affects virtually all physiological processes, the extent to which thermal history mediates the adaptive capacity of marine organisms to climate change has been largely overlooked. Using populations of a marine gastropod (Turbo undulatus) with different thermal histories (cool vs. warm), we compared their physiological adjustments following exposure (8-week) to ocean acidification and warming. Compared to cool-acclimated counterparts, we found that warm-acclimated individuals had higher thermal threshold (i.e. increased CTmax by 2°C), which was unaffected by the exposure to ocean acidification and warming. Thermal history also strongly mediated physiological effects, where warm-acclimated individuals adjusted to warming by conserving energy, suggested by lower respiration and ingestion rates, energy budget (i.e. scope for growth) and O:N ratio. After exposure to warming, warm-acclimated individuals had higher metabolic rates and greater energy budget due to boosted ingestion rates, but such compensatory feeding disappeared when combined with ocean acidification. Overall, we suggest that thermal history can be a critical mediator of physiological performance under future climatic conditions. Given the relatively gradual rate of global warming, marine organisms may be better able to adaptively adjust their physiology to future climate than what short-term experiments currently convey.

Continue reading ‘Long-term thermal acclimation drives adaptive physiological adjustments of a marine gastropod to reduce sensitivity to climate change’

The effect of acidified seawater on shell characteristics of blood cockle, Tegillarca granosa

Our ocean currently has been recorded to absorb about 25% of anthropogenic CO2 on an annual basis. This has estimated the global average sea surface pH to decrease from 8.2 to 8.1 units since the pre-industrial revolution and to further drop between 0.1 to 0.3 units by the end of the 21st century. This possesses a potential impact on wide range of marine organismschr(’39’) especially marine calcifiers where the CO32- is a fundamental mineral for shell and skeleton formation. In a 7-day experiment, this study investigated the effect of different pH treatments, which were pH 7.10, pH 7.50 and control pH (pH 7.81) on shell properties of the blood cockle, Tegillarca granosa. The shell weight and shell density of T. granosa was significantly reduced at pH 7.10. The smaller mean ratio for weight and density at pH 7.10 indicated there was a large difference between the initial and final value for weight and density. Furthermore, the scanning electron micrograph revealed the rough outer shell surface (periostracum) of T. granosa under decreased pH treatment (pH 7.10). However, the ocean acidification level of pH 7.50 which predicted to occur by the year 2300 showed no significant decrease in shell weight and shell density of T. granosa compared to the control pH treatment (pH 7.81).

Continue reading ‘The effect of acidified seawater on shell characteristics of blood cockle, Tegillarca granosa’

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Ocean acidification in the IPCC AR5 WG II

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