Posts Tagged 'mortality'

Potential for maternal effects on offspring CO2 sensitivities in the Atlantic silverside (Menidia menidia)

Highlights

• Offspring produced by different females varied in their sensitivity to high CO2 conditions.
• Specific fatty acids in eggs were correlated to the log-transformed CO2 response ratio of embryo survival and hatch length.
• Maternal provisioning might be an additional determinant of CO2 sensitivity in fish early life stages.

Abstract

For marine fish, the influence of maternal provisioning on offspring sensitivity to high carbon dioxide (CO2) conditions remains unknown. We separately reared offspring obtained from five wild-caught Atlantic silverside (Menidia menidia) females from fertilization to 16 days post hatch under contrasting CO2 conditions (ambient: ~ 400 μatm, acidified: ~ 2,300 μatm), testing whether average survival during the embryo and larval stage, hatch length, final length, and growth rates were affected by CO2, female identity, or their interaction. Average trait responses did not significantly differ between treatments (CO2 or female identity), however, significant CO2 × female identity interactions indicated that females produced offspring with different average CO2 sensitivities. We then examined whether differential egg provisioning with fatty acids (FA) may partially explain the observed differences in offspring CO2 sensitivities. Concentrations of 27 FAs in the unfertilized eggs of each female were measured. Cumulative absolute FA levels were negatively related to hatch length and to the log-transformed CO2 response ratio of hatch length. Eggs with lower concentrations of 20:1n9 and 22:5n3 resulted in offspring where embryo survival was negatively impacted by high CO2. Eggs with higher concentrations of 18:3n3, 18:4n3, and 22:6n3 produced shorter offspring at hatching under high CO2 conditions. These results indicate that maternal provisioning might be an additional determinant of CO2 sensitivity in fish early life stages. Acidification experiments should therefore utilize large numbers of parents from different natural conditions and, where possible, track heritage.

Continue reading ‘Potential for maternal effects on offspring CO2 sensitivities in the Atlantic silverside (Menidia menidia)’

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’

Effects of high pCO2 on early life development of pelagic spawning marine fish

The present study investigated the effect of elevated pCO2 on the development of early stages of the pelagic spawning marine fish Solea senegalensis, Diplodus sargus and Argyrosomus regius. Eggs and larvae were reared under control (pH 8.0, ~570 μatm) and two elevated pCO2 conditions (pH 7.8, ~1100 μatm; pH 7.6, ~1900 μatm) until mouth opening (3 days post-hatching). Egg size did not change with exposure to elevated pCO2, but hatching rate was significantly reduced under high pCO2 for all three species. Survival rate was not affected by exposure to increased pCO2, but growth rate was differently affected across species, with A. regius growing faster in the mid-level pCO2 treatment compared with control conditions. S. senegalensis and A. regius hatched with smaller yolk sacs under increased pCO2 but endogenous reserves of D. sargus were not affected. Otoliths were consistently larger under elevated pCO2 conditions for all the three species. Differences among egg batches and a significant interaction between batch and pCO2 suggest that other factors, such as egg quality, can influence the response to increased pCO2. Overall, the results support the occurrence of a species-specific response to pCO2, but highlight the need for cautious analysis of potential sensitivity of species from unreplicated observations.

Continue reading ‘Effects of high pCO2 on early life development of pelagic spawning marine fish’

Southern Ocean pteropods at risk from ocean warming and acidification

Early life stages of marine calcifiers are particularly vulnerable to climate change. In the Southern Ocean aragonite undersaturation events and areas of rapid warming already occur and are predicted to increase in extent. Here, we present the first study to successfully hatch the polar pteropod Limacina helicina antarctica and observe the potential impact of exposure to increased temperature and aragonite undersaturation resulting from ocean acidification (OA) on the early life stage survival and shell morphology. High larval mortality (up to 39%) was observed in individuals exposed to perturbed conditions. Warming and OA induced extensive shell malformation and dissolution, respectively, increasing shell fragility. Furthermore, shell growth decreased, with variation between treatments and exposure time. Our results demonstrate that short-term exposure through passing through hotspots of OA and warming poses a serious threat to pteropod recruitment and long-term population viability.

Continue reading ‘Southern Ocean pteropods at risk from ocean warming and acidification’

Responses of photosynthesis and CO2 concentrating mechanisms of marine crop Pyropia haitanensis thalli to large pH variations at different time scales

Highlights

• A pH of 4, 5, and 9 resulted in the death of Pyropia haitanensis thalli.
• A pH of 6 and 7 increased the growth of Pyropia haitanensis thalli.
• The CO2 concentrating mechanisms may play a role in intracellular pH homeostasis.
• Actual pH variation needs to be considered in relative studies.
Abstract

Wild and cultivated populations of Pyropia haitanensis have frequently experienced extremely low pH conditions in the last few decades. This could potentially threaten the development of the aquaculture of this economically important marine crop. To gain a broader perspective, we investigated the short- (4 h) and long- (7 days) term responses of CO2 concentrating mechanisms (CCMs) of P. haitanensis thalli to large variations in pH. Our study found that a pH of 4 and 5, which mimicked the decreased pH caused by acid rain, resulted in decreased photosynthesis and respiration while leading to the death of P. haitanensis thalli. Thus, acid rain would result in a decline in P. haitanensis production and threaten wild seaweed sources. However, a pH of 6 and 7 enhanced the growth of P. haitanensis thalli by > 30%, mainly because increased CO2 levels favored photosynthesis, while the algae need to effectively maintain intracellular pH homeostasis to support rapid growth rates. The contributions of extracellular carbonic anhydrases (eCAs) to photosynthetic rates remained at > 77% when pH ≥ 7, regardless of the treatment time. However, at pH 6, the contribution of eCAs to photosynthesis increased from 25% for a short-term treatment to 66% for a long-term treatment. Thus, except for work on carbon assimilation, this study proposes that the CCMs component involved in the movement and metabolism of inorganic carbon may play an important role in pH homeostasis. In addition, pH 9 also led to the death of P. haitanensis thalli, which is consistent with observations of the natural distribution of this algae and hints that P. haitanensis thalli prefer to use inorganic carbon via eCAs when pH ≥ 7. The present study suggested that the actual variation in pH experienced by marine organisms needs to be considered in the experimental design of related studies.

Continue reading ‘Responses of photosynthesis and CO2 concentrating mechanisms of marine crop Pyropia haitanensis thalli to large pH variations at different time scales’

Reproductive and trans-generational effect of ocean acidification and warming on the coral Stylophora pistillata in the Gulf of Aqaba

Global warming is threatening 75 % of the world’s coral reefs. The reproduction of corals is a driver for the development of the whole reef ecosystem. Then, it is essential to better understand the transgenerational mechanisms in the response of parents and offspring to elevated temperature and lowered pH. Colonies of Stylophora pistillata from the Gulf of Aqaba during their reproduction period were exposed to a 4°C increase in temperature and a pH of 7.6 for 36 days, then a 6°C increase for six days. Planulae were counted on seven consecutive nights, two times during the experiment period. Physiological characteristics of adult and planulae were assessed on four and five sampling points respectively, as well as the behaviour of the planulae through their incubation. Results show no effect of OWA on the reproduction, parents, and planulae physiology. They suggest that the natural resistance of corals in the Gulf of Aqaba is transmitted from parent to offspring. Data on planulae quantity, survival, settlement, and metabolism provides additional and useful information to understand the biology of this coral, specially in its early-life stage. This study’s outcome is adding evidences of the future development of corals reefs in this region, unlike several other tropical reefs in the world.

Continue reading ‘Reproductive and trans-generational effect of ocean acidification and warming on the coral Stylophora pistillata in the Gulf of Aqaba’

pH effects in the acute toxicity study of the crude oil-WAF (water accommodated fraction) in the whiteleg shrimp, Litopenaeus vannamei

Oil spillage can cause harmful risks to marine ecology in a short time period and may lead to devastating long-term impacts. Meanwhile, the trends of a pH decrease due to ocean acidification deteriorate spillages’ impact. This study evaluated the influence of pH on crude oil water accommodated fraction (WAF) toxicity to the whiteleg shrimp, Litopenaeus vannamei. Post larvae of the shrimps were exposed to the crude oil-WAF with concentrations of 0%, 25%, 50%, 75%, and 100% under pH concentrations of 6.5 and 8.5 for 72 hours to quantify their mortality. The polycyclic aromatic hydrocarbons (PAHs) of the WAF were analyzed using the GC-MS method, while the LC50 was determined using probit analysis. L. vannamei showed impaired swimming ability, loss of balance, comatose, and even death when the shrimp were acutely exposed to the crude oil WAF. The 72-h LC50 were slightly lower in pH 6.5 than that of 8.5 (101.7±9.6 mL L-1 and 114.67±11.7 mL L-1 respectively). There were 14 PAH compounds presented in the crude oil-WAF in which carcinogenic compound, benzo[a]pyrene, represented 25% of the total concentration of PAHs. The interaction among PAHs may lead synergistic effects that could increase the mortality of the shrimps. However, based on the US EPA’s LC50 scale, the crude oil-WAF is still practically non-toxic to the whiteleg shrimp, L. vannamei.

Continue reading ‘pH effects in the acute toxicity study of the crude oil-WAF (water accommodated fraction) in the whiteleg shrimp, Litopenaeus vannamei’


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