Archive for April, 2020

Researchers: dissolved oxygen and pH policy leave fisheries at risk

Stony Brook University’s Christopher J. Gobler, Endowed Chair of Coastal Ecology and Conservation, and Stephen J. Tomasetti, Science Teaching and Research to Inform Decisions (STRIDE) fellow, consider accumulating scientific evidence on the harmful effects of coastal hypoxia (low oxygen) and acidification (decreasing pH, increasing acidity) in coastal ecosystems in the April 24 issue of the journal Science.

In a Policy Forum, Dissolved oxygen and pH criteria leave fisheries at risk, the scientists suggest approaches that would address current policy shortfalls and facilitate improved protection of aquatic life.

Continue reading ‘Researchers: dissolved oxygen and pH policy leave fisheries at risk’

Ocean warming and acidification may drag down the commercial Arctic cod fishery by 2100

The Arctic Ocean is an early warning system for indicators and effects of climate change. We use a novel combination of experimental and time-series data on effects of ocean warming and acidification on the commercially important Northeast Arctic cod (Gadus morhua) to incorporate these physiological processes into the recruitment model of the fish population. By running an ecological-economic optimization model, we investigate how the interaction of ocean warming, acidification and fishing pressure affects the sustainability of the fishery in terms of ecological, economic, social and consumer-related indicators, ranging from present day conditions up to future climate change scenarios. We find that near-term climate change will benefit the fishery, but under likely future warming and acidification this large fishery is at risk of collapse by the end of the century, even with the best adaptation effort in terms of reduced fishing pressure.

Continue reading ‘Ocean warming and acidification may drag down the commercial Arctic cod fishery by 2100’

Dissolved oxygen and pH criteria leave fisheries at risk

Changes in human population centers and agricultural fertilizer use have accelerated delivery rates of nitrogen and phosphorus to coastal waters, often stimulating rapid accumulations of primary production (1). Whereas resulting eutrophication processes are of less environmental relevance in well-mixed, ocean ecosystems, when they occur in warm, stratified, and/or poorly mixed waters, they can result in hypoxia [depletion of dissolved oxygen (DO)] and acidification (decrease in pH), both of which individually can have adverse effects on aquatic life, affecting a suite of physiological processes and increasing mortality rates (2, 3). Only recently, however, have studies of aquatic hypoxia begun to consider coeffects of low pH (4). Many ecologically and/or economically important shellfish and finfish that experience decreased survival and/or growth when exposed to hypoxia are further impaired by concurrent acidification (4). Yet although scientific understanding of DO and pH variability and documentation of coastal hypoxic and acidification events have improved, regulatory reform has not kept pace. We suggest that more stringent DO and pH numeric criteria be considered to account for the negative effects of low pH on marine life and the combined impairment from low DO and low pH.

Continue reading ‘Dissolved oxygen and pH criteria leave fisheries at risk’

Planktonic stages of the ecologically important sea urchin, Diadema africanum: larval performance under near future ocean conditions

Diadema africanum is a recently described sea urchin from the Eastern Atlantic archipelagos, and adults play a major ecological role mediating the transition between two alternative ecosystem states: macroalgal beds and urchin barrens. The aim of this study was to describe for the first time the egg characteristics, fertilization and larval development. To determine basic life-history characteristics for this species, we reared larvae through to metamorphic competence under an energy shortage experiment and temperature–pH experiments to characterize the morphological plasticity of larval responses to actual and future oceanic conditions. D. africanum produces eggs that are larger both in diameter (82.7 μm) and volume (0.30 nl) than the eggs of both Diadema antillarum (70.0 μm, 0.18 nl) and Diadema mexicanum (68.0 μm, 0.16 nl). Larval development is similar to other species within the Family Diadematidae, with a Echinopluteus transversus larval type morphology. The combined effects of the climate change-related environmental factors resulted in a reduction in fitness of D. africanum at the warmer limit of its thermal range when combined with low pH. Results suggest that the egg and larval life-history characteristics of D. africanum may have evolved to facilitate long-distance oceanic transport; however, near-future oceanic conditions may compromise larval survival.

Continue reading ‘Planktonic stages of the ecologically important sea urchin, Diadema africanum: larval performance under near future ocean conditions’

Effects of ocean acidification on phenology and epiphytes of the seagrass Posidonia oceanica at two CO2 vent systems of Ischia (Italy)

Morphological features of the seagrass Posidonia oceanica (L.) Delile and its epiphyte community were studied in three acidified stations located in two CO2 vents systems and one control station under normal pH conditions off the island of Ischia (Italy) to highlight the possible effects of ocean acidification. Plant phenology was analyzed every two months for a year cycle (June 2016–April 2017), while epiphytes were studied in the period of highest development of both the leaf canopy and the epiphytic community (June, August, and October 2016). The shoot density of Posidonia beds in the acidified stations of the studied sites was significantly higher than that in the control area. Significant differences in the mean leaf length according to the pH condition, month, and the interaction of these two factors were observed (PERMANOVA); the mean leaf width differed also among pH conditions and months. We recorded lower leaf lengths and widths in the acidified stations in all the considered months, compared to those in the control station. These differences are consistent with the higher impact of grazing by the herbivorous fish Sarpa salpa observed on the leaves in the acidified stations. However, the overall leaf surface available for epiphytes was similar among stations because of the higher shoot density under ocean acidification conditions. Overall, the composition and structure of the epiphytic community on the Posidonia leaves showed significant differences in relation to acidification: in both acidified sites, all the calcareous forms, both encrusting red algae (Corallinales) and animals (bryozoans, foraminiferans, and spirorbids), disappeared or were strongly reduced, in favor of encrusting or erect fleshy algae, and non-calcifying invertebrates (hydrozoans, tunicates) which dominated the assemblage. Coralline algae are early species in the epiphytic colonization of P. oceanica and therefore their absence can further modify the pattern of leaf colonization by other species. Therefore, the changes found in the epiphyte community in low pH areas could have potential cascading effects on the seagrass trophic network and the functioning of the system.

Continue reading ‘Effects of ocean acidification on phenology and epiphytes of the seagrass Posidonia oceanica at two CO2 vent systems of Ischia (Italy)’

Sea urchins reveal how organisms respond to a changing marine environment

Coastal marine invertebrates are important around the world with regard to the ecosystem services and functions that they provide. Can these species adapt and evolve to cope with multiple stressors at the rate at which they are occurring due to climate change?

The world’s oceans are changing faster than at any other time over the last 300 million years. As a result, marine animals are being exposed to multiple rapid environmental changes. At the same time, seasonal and daily variability in environmental conditions such as temperature and ocean acidification are increasing.

Continue reading ‘Sea urchins reveal how organisms respond to a changing marine environment’

Abyssal oceanic circulation and acidification during the Middle Eocene Climatic Optimum (MECO)

The Middle Eocene Climatic Optimum (MECO) is a global warming event that occurred at around 40 Ma and lasted about 500 kyr. We study this event in an abyssal setting of the Tasman Sea, using the IODP Core U1511B-16R, collected during the expedition 371. We analyse magnetic, mineralogical, and chemical parameters to investigate the evolution of the sea bottom conditions at this site during the middle Eocene. We observe significant changes indicating the response to the MECO perturbation. Mn oxides, in which Mn occurs under an oxidation state around +4, indicate a high Eh water environment. A prominent Mn anomaly, occurring just above the MECO interval, indicates a shift toward higher pH conditions shortly after the end of this event. Our results suggest more acid bottom water over the Tasman abyssal plain during the MECO, and an abrupt end of these conditions. This work provides the first evidence of MECO at abyssal depths and shows that acidification affected the entire oceanic water column during this event.

Continue reading ‘Abyssal oceanic circulation and acidification during the Middle Eocene Climatic Optimum (MECO)’

Effects of pH on salicylic acid toxicity in terms of biomarkers determined in the marine gastropod Gibbula umbilicalis

Highlights

• Physiological alterations were enhanced under SA exposure at lower pH levels.

• Lipid peroxidation increased after seawater acidification.

• Neurotoxic effects were reported under SA exposure.

• Prostaglandins biosynthesis pathway inhibited by SA absorption at lower pH levels.

Abstract

Alterations of the physical-chemical properties of the oceans due to anthropogenic activities are, at present, one of the most concerning environmental issues studied by researchers. One of these issues is ocean acidification, mainly caused by overproduction and release of carbon dioxide (CO2) from anthropogenic sources. Another component of environmental degradation is related to the production and release of potential toxic compounds, namely active pharmaceutical ingredients, into the aquatic environment that, combined with oceanic acidification, can cause unpredictable and never before considered deleterious effects on non-target marine organisms. Regarding this issue, the hereby study used predictions of future ocean acidification to simulate realistic scenarios of environmental exposure to a common therapeutic drug, salicylic acid (SA), in the marine gastropod Gibbula umbilicalis under different pH values. This species was exposed to a range of pH values (8.2, 7.9 and 7.6), and to already reported environmentally realistic concentrations (5, 25 and 125 μg/L) of SA. To evaluate the effects of these environmental stressors, key physiological biomarkers (GSTs, CAT, TBARS, AChE and COX) and shell hardness (SH) were quantified. Results from the present study showed that CAT and GSTs activities were enhanced by SA under water acidification; increased lipid peroxidation was also observed in organisms exposed to SA in more acidic media. In addition, the hereby study demonstrated the neurotoxic effects of SA through the inhibition of AChE. Effects were also observed in terms of COX activity, showing that SA absorption may be affected by water acidification. In terms of SH, the obtained data suggest that SA may alter the physical integrity of shells of exposed organisms. It is possible to conclude that the combination of seawater acidification and exposure to toxic xenobiotics (namely to the drug SA) may be strenuous to marine communities, making aquatic biota more susceptible to xenobiotics, and consequently endangering marine life in an unpredictable extent.

Continue reading ‘Effects of pH on salicylic acid toxicity in terms of biomarkers determined in the marine gastropod Gibbula umbilicalis’

Ocean acidification partially mitigates the negative effects of warming on the recruitment of the coral, Orbicella faveolata

Ocean acidification and ocean warming constitute major threats to many calcifying reef organisms, including scleractinian corals. The combined effects of these two environmental stressors on the earliest life history stages of reef calcifiers remain poorly studied, particularly for Atlantic corals. Here, we investigate how acidification and warming influence the fertilization success, larval survivorship, and larval settlement of the threatened Atlantic coral, Orbicella faveolata. Gametes and larvae from O. faveolata were subjected to a factorial combination of warming (ambient versus + 1.5 °C) and acidification (ambient versus − 0.2 pH units) projected to occur by the year 2050. O. faveolata individuals were maintained in the same treatments throughout all early life history stages investigated. The fertilization success of O. faveolata was not affected by acidification, warming, or their combination. However, during larval development, warming caused complete mortality and prevented any subsequent settlement. Interestingly, these negative effects of warming were mitigated when combined with ocean acidification, such that both larval survivorship and settlement increased by 41% in the combined treatment relative to the isolated warming treatment. Our research suggests that temperature-induced increases in larval metabolism may be counterbalanced by acidification, which serves to reduce larval metabolism. Notwithstanding, larval survivorship and settlement were still reduced by 50% under combined acidification and warming relative to the ambient treatment, indicating that climate change will continue to serve as major stressor during the early life history stages of corals, jeopardizing the resilience of Caribbean reefs.

Continue reading ‘Ocean acidification partially mitigates the negative effects of warming on the recruitment of the coral, Orbicella faveolata’

Molecular response of a coral reef fish (Acanthochromis polyacanthus) to climate change

Marine ecosystems are already threatened by the effects of climate change through increases in ocean temperatures and pCO2 levels due to increasing atmospheric CO2. Marine fish living close to their thermal maximum have been shown to be especially vulnerable to temperatures exceeding that threshold, and even relatively small increases in elevated pCO2 levels have led to behavioral impairments with amplified predation risks. These ongoing threats highlight the need for further understanding of how these changes will impact fish and if any potential for adaptation or acclimation exists. The coral reef fish, Acanthochromis polyacanthus, has been well studied in response to singular environmental changes both through its phenotype and molecular expression profiles within and across generations. However, key questions regarding transgenerational heritability and molecular responses to multiple environmental changes have not been addressed. To further understand A. polyacanthus I examined the mechanisms behind heritability of behavioral tolerance to elevated pCO2 in an attempt to determine the maternal and paternal contributions to this phenotype. There was a strong impact of parental phenotype on the expression profiles of their offspring regardless of environmental exposure. Offspring from both parental pairs expressed mechanisms involved in tolerance to ocean acidification suggesting this phenotype is reliant on input from both parents. Creation of a new proteomic resource, a SWATH spectral library, delivered a closer examination of the link between phenotypic and expression changes. Analysis on different constructed libraries led to the use of an organism whole library combined with study specific data to analyze proteomic changes in A. polyacanthus under the combined environmental changes of ocean acidification and warming. With direct comparisons to transcriptomic changes in the same individuals I identified an additive effect of elevated pCO2 and temperature associated with decreases in growth and development. However, a strong role of parental identity on the expression profiles of offspring reinforced the high genetic variability of this species. This thesis provides novel insights into the heritability of phenotypic traits and the molecular responses to combined stressors in A. polyacanthus, as well as presenting a new resource for proteomic studies in this fish and other non-model species.

Continue reading ‘Molecular response of a coral reef fish (Acanthochromis polyacanthus) to climate change’


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