Posts Tagged 'biological response'

Exploring coastal acidification and oyster restoration activities on the United States Atlantic coast

Executive Summary

The global ocean mediates the effect of climate change and anthropogenic carbon emissions by absorbing atmospheric carbon dioxide (Ellis et al., 2017). The ocean’s absorption of carbon dioxide results in a change in ocean chemistry and decline in seawater pH known as ocean acidification (Kapsenberg and Cyronak, 2018). Changes in ocean chemistry and pH may also be driven by primary production activity, upwelling, and river runoff into marine environments (Richards et al., 2014). Ocean acidification has the potential to adversely affect numerous marine organisms (Kapsenberg and Cyronak, 2018), however, it can be especially problematic for calcifying shellfish species (Swezey et al., 2020) like the Eastern Oyster and larval or juvenile stage organisms (Mangi et al., 2018). Temperature, salinity, dissolved oxygen levels, and acidification impact the health and longevity of oysters and oyster reefs. Oyster reefs offer numerous ecosystem services. These reefs provide habitat for benthic invertebrates, seabirds and fish that rely on reefs for feeding, nursery, and breeding grounds (Burrows et al., 2005). The Eastern Oyster (Crassostrea virginica) is a native oyster species of the U.S. Atlantic Coast. Although oysters reefs support coastal livelihoods and offer numerous ecosystem services, many reefs have been degraded by anthropogenic activities (Burrows et al., 2005). Pollution, over-harvest, and an increase in loading of suspended sediments are key threats to oyster reef health (Burrows et al., 2005). Oyster reef restoration projects focus on returning reefs to their natural state. Given the role of oysters as ecosystem engineers, and the many benefits that may be derived from healthy oyster reefs, restoration projects are a priority for communities throughout the U.S. Atlantic Coast.

Cooley et al. 2016 recommends several effective community actions that may be taken to help address ocean acidification today. This project focuses on two non-legislative actions discussed by Cooley et al. 2016. These are public education related to coastal acidification and resilience management through oyster reef restoration projects. The purpose of this project is to support coastal resource-reliant communities on the U.S. Atlantic Coast in preparing for the potential future impacts of ocean acidification on C. virginica. The project examines trends in the oyster reef restoration projects presently underway at the state and local level along the U.S. Atlantic Coast, and it considers how coastal acidification may affect the longevity of the region’s oyster reefs. Finally, the project considers the future research and management considerations needed to adequately protect oyster reefs under changing climatic conditions.

Continue reading ‘Exploring coastal acidification and oyster restoration activities on the United States Atlantic coast’

Exposure time modulates the effects of climate change-related stressors on fertile sporophytes and early-life stage performance of a habitat-forming kelp species

Highlight

  • Ocean warming (OW) reduced the sorus photosynthetic performance.
  • OW reduced meiospore germination rate.
  • OW and ocean acidification reduced meiospore release (MR).
  • MR is more sensitive to temperature changes than to pCO2 changes.
  • Longer exposure to OW increased the negative effects on germination rate.

Abstract

Understanding the impact of increases in pCO2 (OA) and extreme changes in temperature on marine organisms is critical to predicting how they will cope with climate change. We evaluated the effects of OA as well as warming and cooling trend temperature on early reproductive traits of Lessonia trabeculata, a foundation kelp species. Sori discs were maintained for an exposure time (ET) of 3 (T3) and 7 (T7) days to one of two contrasting pCO2 levels (450 and 1100 μatm). In addition, at each pCO2 level, they were subjected to three temperature treatments: 15 °C (control), 10 °C (cool) and 19 °C (warm). Subsequently, we compared sorus photosynthetic performance (Fv/Fm), the number of meiospores released (MR) and their germination rate (GR) after 48 h of settlement, with values obtained from sori discs not exposed (DNE) to the treatments. The Fv/Fm measured for DNE was lower than at T3 and T7 at 10 and 15 °C but not at 19 °C. Regardless of temperature, we found no significant differences between MR measured at T0 and T3 were found. MR at T7 was significantly lower at 19 °C than at 10 and 15 °C. We found only aA significant reduction in MR in response to elevated pCO2 was only found at T3. The GR of meiospores released by DNE and then maintained for 48 h to 19 °C decreased significantly by ∼33 % when compared with those maintained for the same time at 10 and 15 °C. A similar, but more drastic reduction (∼54 %) in the GR was found in meiospores released by sori discs exposed for T3 and maintained for 48 h to 19 °C. We suggest that OA and warming trend will threaten the early establishment of this species with further consequences for the functioning of the associated ecosystem.

Graphical abstract

Under laboratory conditions were investigated the combined effect of pCO2, temperature and the exposure time on sorus photosynthetic performance (Fv/Fm) and meiospore performance (release and germination rate) of a habitat-forming kelp Lessonia trabeculata. The results suggest that important traits such as sorus photosynthetic performance, meiospores released and germination rate can be affected by those stressors and by the extent to which the sori are exposed. We concluded that ocean warming and ocean acidification might threaten the early establishment of this species with further consequences for the ecosystem functioning, goods and services in coastal environments.

Continue reading ‘Exposure time modulates the effects of climate change-related stressors on fertile sporophytes and early-life stage performance of a habitat-forming kelp species’

Differential responses in anti-predation traits of the native oyster Ostrea edulis and invasive Magallana gigas to ocean acidification and warming

Ocean acidification and warming (OAW) pose a threat to marine organisms, with particular negative effects on molluscs, and can jeopardize the provision of associated ecosystem services. As predation is an important factor shaping populations in the marine environment, the ability of organisms to retain traits valuable in predation resistance under OAW may be decisive for future population maintenance. We examine how exposure to seawater temperature (control: 16.8°C and warm: 20°C) and atmospheric pCO2 (ambient [~400], ~750, and ~1000 ppm) conditions affects traits linked to predation resistance (adductor muscle strength and shell strength) in two ecologically and economically important species of oysters (Magallana gigas and Ostrea edulis) and relate them to changes in morphometry and fitness (condition index, muscle and shell metrics). We show that O. edulis remained unimpacted following exposure to OAW scenarios. In contrast, the adductor muscle of M. gigas was 52% stronger under elevated temperature and ~750 ppm pCO2, and its shell was 44% weaker under combined elevated temperature and ~1000 ppm pCO2. This suggests greater resistance to mechanical predation toward the mid-21st century, but greater susceptibility toward the end of the century. For both species, individuals with more somatic tissue held an ecological advantage against predators; consequently, smaller oysters may be favoured by predators under OAW. By affecting fitness and predation resistance, OAW may be expected to induce shifts in predator-prey interactions and reshape assemblage structure due to species and size selection, which may consequently modify oyster reef functioning. This could in turn have implications for the provision of associated ecosystem services.

Continue reading ‘Differential responses in anti-predation traits of the native oyster Ostrea edulis and invasive Magallana gigas to ocean acidification and warming’

Coastal pH variability and the eco-physiological and behavioural response of a coastal fish species in light of future ocean acidification

Ocean acidification (OA) is a global phenomenon referring to a decrease in ocean pH and a perturbation of the seawater carbonate system due to ever-increasing atmospheric CO2 concentrations. In coastal environments, identifying the impacts of OA is complex due to the multiple contributors to pH variability by coastal processes, such as freshwater inflow, upwelling, hydrodynamic processes, and biological activity. The aim of this PhD study was to quantify the local processes occurring in a temperate coastal embayment, Algoa Bay in South Africa, that contribute to pH and carbonate chemistry variability over time (monthly and 24-hour) and space (~10 km) and examine how this variability impacts a local fish species, Diplodus capensis, also commonly known as ‘blacktail’. Algoa Bay, known for its complex oceanography, is an interesting location in which to quantify carbonate chemistry variability. To assess this variability, monitoring sites were selected to coincide with the Algoa Bay Sentinel Site long-term ecological research (LTER) and continuous monitoring (CMP) programmes. The average pH at offshore sites in the bay was 8.03 ± 0.07 and at inshore sites was 8.04 ± 0.15. High pH variability (~0.55–0.61 pH units) was recorded at both offshore (>10 m depth) and inshore sites (intertidal surf zones). Many sites in the bay, especially the atypical site at Cape Recife, exhibit higher than the average pH levels (>8.04), suggesting that pH variability may be biologically driven. This is further evidenced by high diurnal variability in pH (~0.55 pH units). Although the specific drivers of the high pH variability in Algoa Bay could not be identified, baseline carbonate chemistry conditions were identified, which is necessary information to design and interpret biological experiments. Long-term, continuous monitoring is required to improve understanding of the drivers of pH variability in understudied coastal regions, like Algoa Bay.

Continue reading ‘Coastal pH variability and the eco-physiological and behavioural response of a coastal fish species in light of future ocean acidification’

Geographical variation in phenotypic plasticity of intertidal sister limpet’s species under ocean acidification scenarios

Ocean Acidification (OA) can have pervasive effects in calcifying marine organisms, and a better understanding of how different populations respond at the physiological and evolutionary level could help to model the impacts of global change in marine ecosystems. Due to its natural geography and oceanographic processes, the Chilean coast provides a natural laboratory where benthic organisms are frequently exposed to diverse projected OA scenarios. The goal of this study was to assess whether a population of mollusks thriving in a more variable environment (Talcaruca) would present higher phenotypic plasticity in physiological and morphological traits in response to different pCO2 when compared to a population of the same species from a more stable environment (Los Molles). To achieve this, two benthic limpets (Scurria zebrina and Scurria viridula) inhabiting these two contrasting localities were exposed to ocean acidification experimental conditions representing the current pCO2 in the Chilean coast (500 μatm) and the levels predicted for the year 2100 in upwelling zones (1500 (μatm). Our results show that the responses to OA are species-specific, even in this related species. Interestingly, S. viridula showed better performance under OA than S. zebrina (i.e., similar sizes and carbonate content in individuals from both populations; lower effects of acidification on the growth rate combined with a reduction of metabolism at higher pCO2). Remarkably, these characteristics could explain this species’ success in overstepping the biogeographical break in the area of Talcaruca, which S. zebrina cannot achieve. Besides, the results show that the habitat factor has a strong influence on some traits. For instance, individuals from Talcaruca presented a higher growth rate plasticity index and lower shell dissolution rates in acidified conditions than those from Los Molles. These results show that limpets from the variable environment tend to display higher plasticity, buffering the physiological effects of OA compared with limpets from the more stable environment. Taken together, these findings highlight the key role of geographic variation in phenotypic plasticity to determine the vulnerability of calcifying organisms to future scenarios of OA.

Continue reading ‘Geographical variation in phenotypic plasticity of intertidal sister limpet’s species under ocean acidification scenarios’

The Bouraké semi-enclosed lagoon (New Caledonia). A natural laboratory to study the life-long adaptation of a coral reef ecosystem to climate change-like conditions

According to current experimental evidence, coral reefs could disappear within the century if CO2 emissions remain unabated. However, recent discoveries of diverse and high cover reefs that already thrive under extreme conditions seem to contradict these projections. Volcanic CO2 vents, semi-enclosed lagoons and mangrove estuaries are unique study sites where one or more ecologically relevant parameters for life in the oceans are close or even worse than currently projected for the year 2100. These natural analogues of future conditions hold new hope for the future of coral reefs and provide unique natural laboratories to explore how reef species could keep pace with climate change. To achieve this, it is essential to characterize their environment as a whole, and accurately consider all possible environmental factors that may differ from what is expected in the future and that may possibly alter the ecosystem response.

In this study, we focus on the semi-enclosed lagoon of Bouraké (New Caledonia, SW Pacific Ocean) where a healthy reef ecosystem thrives in warm, acidified and deoxygenated water. We used a multi-scale approach to characterize the main physical-chemical parameters and mapped the benthic community composition (i.e., corals, sponges, and macroalgae). The data revealed that most physical and chemical parameters are regulated by the tide, strongly fluctuate 3 to 4 times a day, and are entirely predictable. The seawater pH and dissolved oxygen decrease during falling tide and reach extreme low values at low tide (7.2 pHT and 1.9 mg O2 L−1 at Bouraké, vs 7.9 pHT and 5.5 mg O2 L−1 at reference reefs). Dissolved oxygen, temperature, and pH fluctuates according to the tide of up to 4.91 mg O2 L−1, 6.50 °C, and 0.69 pHT units on a single day. Furthermore, the concentration of most of the chemical parameters was one- to 5-times higher at the Bouraké lagoon, particularly for organic and inorganic carbon and nitrogen, but also for some nutrients, notably silicates. Surprisingly, despite extreme environmental conditions and altered seawater chemical composition, our results reveal a diverse and high cover community of macroalgae, sponges and corals accounting for 28, 11 and 66 species, respectively. Both environmental variability and nutrient imbalance might contribute to their survival under such extreme environmental conditions. We describe the natural dynamics of the Bouraké ecosystem and its relevance as a natural laboratory to investigate the benthic organism’s adaptive responses to multiple stressors like future climate change conditions.

Continue reading ‘The Bouraké semi-enclosed lagoon (New Caledonia). A natural laboratory to study the life-long adaptation of a coral reef ecosystem to climate change-like conditions’

Impact on fertility rate and embryo-larval development due to the association acidification, ocean warming and lead contamination of a sea urchin Echinometra lucunter (echinodermata: echinoidea)

Ocean warming and acidification can cause deleterious effects on marine biota, which may be potentialized when associated with metal pollution. Thus, the aim of this work was to evaluate the effects of pH decrease, temperature increase and lead contamination on fertility rate and embryo-larval development of Echinometra lucunter. Gametes and embryos were exposed at pH 8.2 (control) and 7.5; at 26°C (control) and 28°C; and at lead concentrations of 0 (control), 125, 250 and 500 μg/L. These conditions were tested individually and in combination. The fertilization rate of E. lucunter was only significantly reduced in the treatments where temperature was increased and in the treatment where pH decreased. However, the development rate of the pluteus larvae was significantly affected in the majority of treatments: metal contamination in the higher concentration; decreased pH in all metal concentrations; increased temperature in the highest metal concentration; decreased pH and increased temperature and all variables combined, which is decreased pH, increased temperature and metal contamination in relation to the control group (C). The development test was shown to be more sensitive than the fertilization test in all the studied scenarios. In general, the present study suggests that pH decrease, temperature increase and metal pollution may have a significant impact on E. lucunter reproductive cycle.

Caetano L. S., Pereira T. M., Envangelista J. D., Cabral D. S., Coppo G. C., Alves de Souza L., Anderson A. B., Heringer O. A. & Chippari-Gomes A. R., in press. Impact on fertility rate and embryo-larval development due to the association acidification, ocean warming and lead contamination of a sea urchin Echinometra lucunter (echinodermata: echinoidea). Bulletin of Environmental Contamination and Toxicology. Article (subscription required).

Tidal action and macroalgal photosynthetic activity prevent coastal acidification in an eutrophic system within a semi-desert region

Highlights

  • Macroalgal photosynthesis (MP) controls daily pH variability during low tide.
  • Environmental factors control pH variability at seasonal scale.
  • Ulva lactuca photosynthetic activity increased the pH of seawater.
  • Macrotidal action and MP prevent coastal acidification in an eutrophic system.

Abstract

Nutrient input drive macroalgal blooms and increases in photosynthetic activity in coastal ecosystems. An intense macroalgal photosynthetic activity can increase the surrounding pH and it could prevent the acidification that often follows an eutrophication process. We tested this hypothesis with field sampling and experiments in a macrotidal (up to 9 m in amplitude) coastal system within a semi-desert region with contrasting eutrophic conditions and Ulva lactuca blooms in the northern Argentinean Patagonia (San Antonio Bay). Our results indicate that daily pH variability during low tide could be controlled by the photosynthetic activity of Ulva lactuca under eutrophic conditions. At seasonal scale, the pH variations were related to environmental features, particularly seawater temperature. Both environmental (i.e. high solar radiation, negligible freshwater inputs and, large tidal action) and anthropogenic nutrient inputs into the studied area promote the Ulva lactuca blooms, which in turn increases the surrounding pH in well oxygenated seawater through the intense photosynthetic activity. Our study shows that eutrophication instead of being a driver of acidification, could contribute to its prevention in well oxygenated marine coastal systems located within semi-desert regions.

Continue reading ‘Tidal action and macroalgal photosynthetic activity prevent coastal acidification in an eutrophic system within a semi-desert region’

Climate change impacts on pollutants mobilization and interactive effects of climate change and pollutants on toxicity and bioaccumulation of pollutants in estuarine and marine biota and linkage to seafood security

Highlights

  • Climate change would enhance the mobilization of pollutants.
  • Toxicity of pollutants to aquatic biota can increase with increasing climate change stressors.
  • Combined effects of climate change and pollutants can enhance bioaccumulation of pollutants in seafood organisms.

Abstract

This article provides an overview of the impacts of climate change stressors (temperature, ocean acidification, sea-level rise, and hypoxia) on estuarine and marine biota (algae, crustaceans, molluscs, corals, and fish). It also assessed possible/likely interactive impacts (combined impacts of climate change stressors and pollutants) on pollutants mobilization, pollutants toxicity (effects on growth, reproduction, mortality) and pollutants bioaccumulation in estuarine and marine biota. An increase in temperature and extreme events may enhance the release, degradation, transportation, and mobilization of both hydrophobic and hydrophilic pollutants in the estuarine and marine environments. Based on the available pollutants’ toxicity trend data and information it reveals that the toxicity of several high-risk pollutants may increase with increasing levels of climate change stressors. It is likely that the interactive effects of climate change and pollutants may enhance the bioaccumulation of pollutants in seafood organisms. There is a paucity of literature relating to realistic interactive effects of climate change and pollutants. Therefore, future research should be directed towards the combined effects of climate change stressors and pollutants on estuarine and marine bota. A sustainable solution for pollution control caused by both greenhouse gas emissions (that cause climate change) and chemical pollutants would be required to safeguard the estuarine and marine biota.

Continue reading ‘Climate change impacts on pollutants mobilization and interactive effects of climate change and pollutants on toxicity and bioaccumulation of pollutants in estuarine and marine biota and linkage to seafood security’

Combined effects of ocean acidification and elevated temperature on feeding, growth, and physiological processes of Antarctic krill Euphausia superba

Antarctic krill Euphausia superba is a key species in the Southern Ocean, where its habitat is projected to undergo continued warming and increases in pCO2. Experiments during 2 summer field seasons at Palmer Station, Antarctica, investigated the independent and interactive effects of elevated temperature and pCO2 (decreased pH) on feeding, growth, acid-base physiology, metabolic rate, and survival of adult Antarctic krill. Ingestion and clearance rates of chlorophyll were depressed under low pH (7.7) compared to ambient pH (8.1) after a 48 h acclimation period, but this difference disappeared after a 21 d acclimation. Growth rates were negligible and frequently negative, but were significantly more negative at high (3°C, -0.03 mm d-1) compared to ambient temperature (0°C, -0.01 mm d-1) with no effect of pH. Modest elevations in tissue total CO2 and tissue pH were apparent at low pH but were short-lived. Metabolic rate increased with temperature but was suppressed at low pH in smaller but not larger krill. Although effects of elevated temperature and/or decreased pH were mostly sublethal, mortality was higher at high temperature/low pH (58%) compared to ambient temperature/pH or ambient temperature/low pH (>90%). This study identified 3 dominant patterns: (1) shorter-term effects were primarily pH-dependent; (2) krill compensated for lower pH relatively quickly; and (3) longer-term effects on krill growth and survival were strongly driven by temperature with little to no pH effect.

Continue reading ‘Combined effects of ocean acidification and elevated temperature on feeding, growth, and physiological processes of Antarctic krill Euphausia superba’

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Ocean acidification in the IPCC AR5 WG II

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