Posts Tagged 'performance'

Effect of elevated pCO2 on competition between the scleractinian corals Galaxea fascicularis and Acropora hyacinthus

Highlights

• The effect of high pCO2 on competitive mechanisms employed by corals was investigated.
• The corals Galaxea fascicularis and Acropora hyacinthus were studied in Monaco.
• The coral Galaxea fascicularis produced mesenterial filaments faster under high pCO2.
• Mesenterial filaments caused similar tissue damage in each pCO2 treatment after 7 days.

Abstract

Ocean acidification is expected to affect coral reefs in multiple ways, in part, by depressing the calcification of scleractinian corals. To evaluate how coral communities will respond to ocean acidification, research into the effects on ecological processes determining community structure is now needed. The present study focused on corals utilizing soft tissues (i.e., mesenterial filaments) as agonistic mechanism, and evaluated their ability to compete for space under ocean acidification. Using aquarium-reared specimens in Monaco, single polyps of Galaxea fascicularis were paired with branch tips of Acropora hyacinthus to stimulate competitive interactions, which were evaluated through the production and use of mesenterial filaments in causing tissue damage under ambient (~ 600 μatm) and elevated pCO2 (~ 1200 μatm). At 1200 μatm pCO2, and when paired with A. hyacinthus, the extrusion of mesenterial filaments from G. fascicularis occurred 2 days earlier than under ambient pCO2, although ultimately the mesenterial filaments caused the same amount of tissue necrosis on A. hyacinthus under both pCO2 regimes after 7 days. This outcome supports the hypothesis that some kinds of competitive mechanisms utilized by scleractinian corals (i.e., mesenterial filaments) will be unaffected by short exposure to pCO2 as high as 1200 μatm.

Continue reading ‘Effect of elevated pCO2 on competition between the scleractinian corals Galaxea fascicularis and Acropora hyacinthus’

An interplay between plasticity and parental phenotype determines impacts of ocean acidification on a reef fish

The impacts of ocean acidification will depend on the ability of marine organisms to tolerate, acclimate and eventually adapt to changes in ocean chemistry. Here, we use a unique transgenerational experiment to determine the molecular response of a coral reef fish to short-term, developmental and transgenerational exposure to elevated CO2, and to test how these responses are influenced by variations in tolerance to elevated CO2 exhibited by the parents. Within-generation responses in gene expression to end-of-century predicted CO2 levels indicate that a self-amplifying cycle in GABAergic neurotransmission is triggered, explaining previously reported neurological and behavioural impairments. Furthermore, epigenetic regulator genes exhibited a within-generation specific response, but with some divergence due to parental phenotype. Importantly, we find that altered gene expression for the majority of within-generation responses returns to baseline levels following parental exposure to elevated CO2 conditions. Our results show that both parental variation in tolerance and cross-generation exposure to elevated CO2 are crucial factors in determining the response of reef fish to changing ocean chemistry.

Continue reading ‘An interplay between plasticity and parental phenotype determines impacts of ocean acidification on a reef fish’

The effect of elevated carbon dioxide on the sinking and swimming of the shelled pteropod Limacina retroversa

Shelled pteropods are planktonic molluscs that may be affected by ocean acidification. Limacina retroversa from the Gulf of Maine were used to investigate the impact of elevated carbon dioxide (CO2) on shell condition as well as swimming and sinking behaviours. Limacina retroversa were maintained at either ambient (ca. 400 µatm) or two levels of elevated CO2 (800 and 1200 µatm) for up to 4 weeks, and then examined for changes in shell transparency, sinking speed, and swimming behaviour assessed through a variety of metrics (e.g. speed, path tortuosity, and wing beat frequency). After exposures to elevated CO2 for as little as 4 d, the pteropod shells were significantly darker and more opaque in the elevated CO2 treatments. Sinking speeds were significantly slower for pteropods exposed to medium and high CO2 in comparison to the ambient treatment. Swimming behaviour showed less clear patterns of response to treatment and duration of exposure, but overall, swimming did not appear to be hindered under elevated CO2. Sinking is used by L. retroversa for predator evasion, and altered speeds and increased visibility could increase the susceptibility of pteropods to predation.

Continue reading ‘The effect of elevated carbon dioxide on the sinking and swimming of the shelled pteropod Limacina retroversa’

Extreme ocean acidification reduces the susceptibility of eastern oyster shells to a polydorid parasite

Ocean acidification poses a threat to marine organisms. While the physiological and behavioural effects of ocean acidification have received much attention, the effects of acidification on the susceptibility of farmed shellfish to parasitic infections are poorly understood. Here we describe the effects of moderate (pH 7.5) and extreme (pH 7.0) ocean acidification on the susceptibility of Crassostrea virginica shells to infection by a parasitic polydorid, Polydora websteri. Under laboratory conditions, shells were exposed to three pH treatments (7.0, 7.5 and 8.0) for 3- and 5-week periods. Treated shells were subsequently transferred to an oyster aquaculture site (which had recently reported an outbreak of P. websteri) for 50 days to test for effects of pH and exposure time on P. websteri recruitment to oyster shells. Results indicated that pH and exposure time did not affect the length, width or weight of the shells. Interestingly, P. websteri counts were significantly lower under extreme (pH 7.0; ~50% reduction), but not moderate (pH 7.5; ~20% reduction) acidification levels; exposure time had no effect. This study suggests that extreme levels – but not current and projected near-future levels – of acidification (∆pH ~1 unit) can reduce the susceptibility of eastern oyster shells to P. websteri infections.

Continue reading ‘Extreme ocean acidification reduces the susceptibility of eastern oyster shells to a polydorid parasite’

Assessing the consequences of environmental impacts: variation in species responses has unpredictable functional effects

Many biological processes underpin ecosystem functioning and health. Determining changes in these processes following disturbance is crucial in assessing the wider impacts on ecosystem function and ultimately ecosystem services. Whilst the focus is often on whether disturbance drives changes in ecosystem function through mortality, sub-lethal effects on the physiology and behaviour of organisms may also have cascading effects on ecosystem processes, functions and services. In this mesocosm study, we investigated the effects of a severe short-term exposure (8 d) to a simulated environmental impact—a leak of a subsea geological CO2 capture and storage reservoir—on key biological processes (bioturbation), an ecosystem function (nutrient cycling) and on the functional group composition for 7 common benthic invertebrate species. We statistically allocated species to functional effect groups based on their measured functional effect relative to other species. Following exposure, we observed behavioural responses driving changes in bioturbation for several species and altered nutrient cycling. Responses were species specific and resulted in shifts in functional effect group composition for some key nutrients (nitrate and silicate). We show that the allocation of species to functional groups by measuring specified ecosystem processes and functions can change following environmental perturbations. This implies that whilst biodiversity and ecosystem functioning are intricately linked, maintaining species identities and abundances after environmental perturbation is no guarantee to maintaining ecosystem functions, as species alter their rate and mode of activity following an environmental stress.

Continue reading ‘Assessing the consequences of environmental impacts: variation in species responses has unpredictable functional effects’

Interactive effects of increased temperature, pCO2 and the synthetic progestin levonorgestrel on the fitness and breeding of the amphipod Gammarus locusta

Highlights

  • Combined effects of temperature, pCO2 and levonorgestrel on G. locusta were assessed.
  • G. locusta was strongly negatively affected under warming exposure (+4 °C).
  • Growth rates were significantly affected by the interactions of LNG with temperature and pCO2.
  • A negative effect of higher temperature and acidification on G. locusta fecundity was observed, contrarily to LNG.
  • Increased temperature and pCO2 were clearly more adverse for G. locusta than exposure to LNG.

Abstract

Given the lack of knowledge regarding climate change-chemical exposure interactions, it is vital to evaluate how these two drivers jointly impact aquatic species. Thus, for the first time, we aimed at investigating the combined effects of increased temperature, pCO2 and the synthetic progestin levonorgestrel on survival, growth, consumption rate and reproduction of the amphipod Gammarus locusta. For that, a full factorial design manipulating temperature [ambient temperature and warming (+4 °C)], pCO2 [normocapnia and hypercapnia (Δ pH 0.5 units)] and the progestin levonorgestrel (LNG: L1 – 10 ngLL−1 and L2 – 1000 ngLL−1, control – no progestin and solvent control – vehicle ethanol (0.01%)) was implemented for 21 days. G. locusta was strongly negatively affected by warming, experiencing higher mortality rates (50–80%) than in any other treatments. Instead, growth rates were significantly affected by interactions of LNG with temperature and pCO2. It was observed, in the short-term (7d) that under ambient temperature (18 °C) and hypercapnic conditions (pH 7.6), the LNG presence promoted the amphipod’s growth, while in the medium-term (21d) this response was not observed. Relative consumption rates (RCRs), during the first week were higher than in the third week. Furthermore, in the first week, RCRs were negatively affected by higher temperature while in the third week, RCRs were negatively affected by acidification. Furthermore, it was observed a negative effect of higher temperature and acidification on G. locusta fecundity, contrarily to LNG. Concluding, the impact of increased temperature and pCO2 was clearly more adverse for the species than exposure to the synthetic progestin, however, some interactions between the progestin and the climate factors were observed. Thus, in a future scenario of global change, the presence of LNG (and other progestins alike) may modulate to a certain level the effects of climate drivers (and vice-versa) on the gammarids fitness and reproduction.

Continue reading ‘Interactive effects of increased temperature, pCO2 and the synthetic progestin levonorgestrel on the fitness and breeding of the amphipod Gammarus locusta’

Local habitat influences on feeding and respiration of the intertidal mussels Perumytilus purpuratus exposed to increased pCO2 levels

Coastal ecosystems are exposed to changes in physical-chemical properties, such as those occurring in upwelling and freshwater-influenced areas. In these areas, inorganic carbon can influence seawater properties that may affect organisms and populations inhabiting benthic habitats such as the intertidal mussel Perumytilus purpuratus. Feeding and metabolic responses were measured in adult mussels from two geographic regions (central and southern Chile) and two local habitats (river-influenced and non-river-influenced) and three pCO2 levels (380, 750, and 1200 μatm pCO2 in seawater). The feeding rates of mussels tend to increase at high pCO2 levels in seawater; however this response was variable across regions and local habitats. In contrast, there was no difference in the respiratory rate of mussels between geographic areas, but there was a significant reduction of oxygen consumption at intermediate and high levels of pCO2. The results indicate that river-influenced organisms compensate for reductions in metabolic cost at elevated pCO2 levels by having their energy demands met, in contrast with non-river-influenced organisms. The lack of regional-scale variability in the physiological performance of mussels may indicate physiological homogeneity across populations and thus potential for local adaptation. However, the local-scale influences of river- and non-river-influenced habitats may counterbalance this regional response promoting intra-population variability and phenotypic plasticity in P. purpuratus. The plasticity may be an important mechanism that allows mussels to confront the challenges of projected ocean acidification scenarios.

Continue reading ‘Local habitat influences on feeding and respiration of the intertidal mussels Perumytilus purpuratus exposed to increased pCO2 levels’


Subscribe to the RSS feed

Powered by FeedBurner

Follow AnneMarin on Twitter

Blog Stats

  • 1,051,359 hits

OA-ICC HIGHLIGHTS

Ocean acidification in the IPCC AR5 WG II

OUP book