Posts Tagged 'biological response'



Boron isotope composition of the cold-water coral Lophelia pertusa along the Norwegian margin: zooming into a potential pH-proxy by combining bulk and high-resolution approaches

High-latitude cold-water coral reefs are particularly vulnerable to climate change due to enhanced CO2 uptake in these regions. To evaluate their physiological functioning and potential application as pH archives, we retrieved both recent and fossil samples of Lophelia pertusa along the Norwegian margin from Oslofjord (59°N), over to Trondheimsfjord, Sula and Lopphavet (70.6°N). Boron isotope analyses (δ11B) were undertaken using solution-based and laser ablation multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS; LA-ICP-MS), and secondary ion mass spectrometry (SIMS). Epi-fluorescence microscopy was employed to provide a rapid pre-screening routine for structure-specific subsampling in the coral skeleton. This integrated approach enabled us to assess heterogeneities within single specimens, as well as to investigate the role of local environmental influences including recent and past variations. All three mass spectrometry methods show substantial differences in the δ11B of the theca wall (TW) and the centres of calcification (COC’s). Micro-bulk subsamples milled from the theca wall of modern specimens originating from different habitats but with comparable seawater pH (8–8.16) gave consistent δ11B values averaging 26.7 (±0.2‰, 2σ, n = 4), while COC subsamples systematically deviated towards lower B/Ca (by ~40%) and depleted δ11B values (minimum 22.7 ± 0.3‰, 2σ), implying a difference of at least 4‰ between TW and COC. SIMS and LA-ICP-MS measurements identified much larger internal heterogeneities with maximum variation of ~10‰ between the distinct skeletal structures; minimal SIMS δ11B values of ~17.3 ± 1.2‰ (2σ) were associated with the pure COC material. Our findings may be interpreted in terms of the occurrence of two main, but likely different, biomineralisation mechanisms in L. pertusa, with the COC’s generally exhibiting minimal pH up-regulation, potentially supporting the use of bicarbonate in the early stages of biomineralisation. Furthermore, we highlight the potential utility of L. pertusa for palaeo-proxy studies if targeting the compositionally homogenous TW zones devoid of COC admixtures, which appear to provide highly reproducible measurements.

Continue reading ‘Boron isotope composition of the cold-water coral Lophelia pertusa along the Norwegian margin: zooming into a potential pH-proxy by combining bulk and high-resolution approaches’

Ecosystem calcification and production in two Great Barrier Reef coral reefs: methodological challenges and environmental drivers

This thesis investigates the drivers of coral reef ecosystem metabolism and the abilities of the different methodologies and analytical approaches to accurately represent reef dynamics. It encompassed tracing natural nutrient additions through bird guano into a coral cay. Developing a new, automated system for measuring carbonate chemistry for coral reef metabolism and the effects of mass coral bleaching on ecosystem functioning were quantified. Overall, it showed that natural nutrient additions and bleaching differentially affect coral reef metabolism and that subtle differences in analytical methods, sampling approaches, and data interpretation techniques can cause significant variation in metabolic estimates.

Continue reading ‘Ecosystem calcification and production in two Great Barrier Reef coral reefs: methodological challenges and environmental drivers’

Pacific geoduck (Panopea generosa) resilience to natural pH variation

Pacific geoduck aquaculture is a growing industry, however little is known about how geoduck respond to varying environmental conditions, or how production might be impacted by low pH associated with ocean acidification. Ocean acidification research is increasingly incorporating multiple environmental drivers and natural pH variability into biological response studies for more complete understanding of the effects of projected ocean conditions. In this study, eelgrass habitats and environmental heterogeneity across four estuarine bays were leveraged to examine low pH effects on geoduck under different natural regimes, using proteomics to assess physiology. Juvenile geoduck were deployed in eelgrass and adjacent unvegetated habitats for 30 days while pH, temperature, dissolved oxygen, and salinity were monitored. Across the four bays pH was lower in unvegetated habitats compared to eelgrass habitats, however this did not impact geoduck growth, survival, or proteomic expression patterns. However, across all sites temperature and dissolved oxygen corresponded to growth and protein expression patterns. Specifically, three protein abundance levels (trifunctional-enzyme β-subunit, puromycin-sensitive aminopeptidase, and heat shock protein 90-⍺) and shell 16 growth positively correlated with dissolved oxygen variability and inversely correlated with mean 17 temperature. These results demonstrate that geoduck are resilient to low pH in a natural setting, 18 and other abiotic factors (i.e. temperature, dissolved oxygen variability) may have a greater 19 influence on geoduck physiology. In addition this study contributes to the understanding of how 20 eelgrass patches influences water chemistry.

Continue reading ‘Pacific geoduck (Panopea generosa) resilience to natural pH variation’

Sub-lethal and lethal toxicities of elevated CO2 on embryonic, juvenile, and adult stages of marine medaka Oryzias melastigma

Highlights

• Adverse effects of elevated CO2 varied cross developmental stages of marine medaka.

• Embryo developmental delay to elevated CO2 showed in concentration-dependent manner.

• Middle stage of development was the most sensitive period to CO2 exposure for mortality.

• Despite transfer to clean water, CO2 exposed embryos could not be recovered.

• Key symptoms by elevated CO2 exposure encompassed mortality and cardiac edema.

Abstract

The potential leakage from marine CO2 storage sites is of increasing concern, but few studies have evaluated the probable adverse effects on marine organisms. Fish, one of the top predators in marine environments, should be an essential representative species used for water column toxicity testing in response to waterborne CO2 exposure. In the present study, we conducted fish life cycle toxicity tests to fully elucidate CO2 toxicity mechanism effects. We tested sub-lethal and lethal toxicities of elevated CO2 concentrations on marine medaka (Oryzias melastigma) at different developmental stages. At each developmental stage, the test species was exposed to varying concentrations of gaseous CO2 (control air, 5%, 10%, 20%, and 30%), with 96 h of exposure at 0–4 d (early stage), 4–8 d (middle stage), and 8–12 d (late stage). Sub-lethal and lethal effects, including early developmental delays, cardiac edema, tail abnormalities, abnormal pigmentation, and mortality were monitored daily during the 14 d exposure period. At the embryonic stage, significant sub-lethal and lethal effects were observed at pH < 6.30. Hypercapnia can cause long-term and/or delayed developmental embryonic problems, even after transfer back to clean seawater. At fish juvenile and adult stages, significant mortality was observed at pH < 5.70, indicating elevated CO2 exposure might cause various adverse effects, even during short-term exposure periods. It should be noted the early embryonic stage was found more sensitive to CO2 exposure than other developmental stages of the fish life cycle. Overall, the present study provided baseline information for potential adverse effects of high CO2 concentration exposure on fish developmental processes at different life cycle stages in marine ecosystems.

Continue reading ‘Sub-lethal and lethal toxicities of elevated CO2 on embryonic, juvenile, and adult stages of marine medaka Oryzias melastigma’

An ocean acidification-simulated system and its application in coral physiological studies

Due to the elevated atmospheric carbon dioxide, ocean acidification (OA) has recently emerged as a research theme in marine biology due to an expected deleterious effect of altered seawater chemistry on calcification. A system simulating future OA scenario is crucial for OA-related studies. Here, we designed an OA-simulated system (OASys) with three solenoid-controlled CO2 gas channels. The OASys can adjust the pH of the seawater by bubbling CO2 gas into seawaters via feedback systems. The OASys is very simple in structure with an integrated design and is new-user friendly with the instruction. Moreover, the OASys can monitor and record real-time pH values and can maintain pH levels within 0.02 pH unit. In a 15-d experiment, the OASys was applied to simulate OA in which the expected target pH values were 8.00, 7.80 and 7.60 to study the calcifying response of Galaxea fascicularis. The results showed daily mean seawater pH values held at pH 8.00±0.01, 7.80±0.01 and 7.61±0.01 over 15 d. Correspondingly, the coral calcification of G. fascicularis gradually decreased with reduced pH.

Continue reading ‘An ocean acidification-simulated system and its application in coral physiological studies’

Sporophytic photosynthesis and gametophytic growth of the kelp Ecklonia stolonifera affected by ocean acidification and warming

Juvenile sporophytes and gametophytes of Ecklonia stolonifera were incubated in combinations of three pCO2 levels (360, 720 and 980 ppmv) and two temperatures (10 and 15°C for sporophytes; 15 and 20°C for gametophytes) to examine potential effects of climate change on photosynthesis and growth. Sporophytes had significantly higher maximum quantum yields (Fv/Fm) and maximum relative electron transport rates (rETRmax) at 720 ppmv than 360 and 980 ppmv. Also, these parameters were significantly lower at higher temperature of 15°C than at 10°C. Growth of female gametophytes was maximal at 360 ppmv rather than enriched pCO2 levels. Female gametophytes had significantly lower growth at higher temperature of 20°C than at 15°C. These results indicate effects of elevated pCO2 varied between generations: stimulating sporophytic photosynthesis and inhibiting gametophytic growth. Ocean acidification and warming would constitute a grave threat to seedling cultivation of E. stolonifera caused by growth inhibition of gametophytes at high pCO2 levels and temperatures.

Continue reading ‘Sporophytic photosynthesis and gametophytic growth of the kelp Ecklonia stolonifera affected by ocean acidification and warming’

Respuesta transgeneracional a la acidificación marina del copépodo Acartia Tonsa Dana, 1849 (in Spanish)

La acidificación oceánica producida por el aumento de la concentración de dióxido de carbono en el océano representa una amenaza para los ecosistemas marinos, porque provoca una disminución del pH y una alteración en la química del agua de mar. El copépodo calanoide marino Acartia tonsa Dana, 1849 es una especie ecológica y socioeconómicamente importante. Este trabajo se centra en cómo afecta el pH ácido al copépodo A. tonsa, determinando la tasa de supervivencia, reproducción y desarrollo a diferentes tratamientos de pH, e intenta averiguar si se produce una respuesta transgeneracional para contrarrestar los efectos de la acidificación oceánica.

Continue reading ‘Respuesta transgeneracional a la acidificación marina del copépodo Acartia Tonsa Dana, 1849 (in Spanish)’


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OA-ICC HIGHLIGHTS

Ocean acidification in the IPCC AR5 WG II

OUP book