Posts Tagged 'crustaceans'

Early life stages of Northern shrimp (Pandalus borealis) are sensitive to fish feed containing the anti-parasitic drug diflubenzuron


• Diflubenzuron is used in salmon aquaculture to remove parasitic lice.
• Salmon feed containing diflubenzuron increased mortality of shrimp larvae.
• Additive effects of diflubenzuron and ocean acidification/warming on mortality.
• More serious sublethal effects of diflubenzuron under future climate conditions.
• Use of diflubenzuron in salmon farms is a threat to non-target crustaceans.


Increasing use of fish feed containing the chitin synthesis inhibiting anti-parasitic drug diflubenzuron (DFB) in salmon aquaculture has raised concerns over its impact on coastal ecosystems. Larvae of Northern shrimp (Pandalus borealis) were exposed to DFB medicated feed under Control conditions (7.0 °C, pH 8.0) and under Ocean Acidification and Warming conditions (OAW, 9.5 °C and pH 7.6). Two weeks’ exposure to DFB medicated feed caused significantly increased mortality. The effect of OAW and DFB on mortality of shrimp larvae was additive; 10% mortality in Control, 35% in OAW, 66% in DFB and 92% in OAW + DFB. In OAW + DFB feeding and swimming activity were reduced for stage II larvae and none of the surviving larvae developed to stage IV. Two genes involved in feeding (GAPDH and PRLP) and one gene involved in moulting (DD9B) were significantly downregulated in larvae exposed to OAW + DFB relative to the Control. Due to a shorter intermoult period under OAW conditions, the OAW + DFB larvae were exposed throughout two instead of one critical pre-moult period. This may explain the more serious sub-lethal effects for OAW + DFB than DFB larvae. A single day exposure at 4 days after hatching did not affect DFB larvae, but high mortality was observed for OAW + DFB larvae, possibly because they were exposed closer to moulting. High mortality of shrimp larvae exposed to DFB medicated feed, indicates that the use of DFB in salmon aquaculture is a threat to crustacean zooplankton.

Continue reading ‘Early life stages of Northern shrimp (Pandalus borealis) are sensitive to fish feed containing the anti-parasitic drug diflubenzuron’

pH controls spermatozoa motility in the Pacific oyster (Crassostrea gigas)

Investigating the roles of chemical factors stimulating and inhibiting sperm motility is required to understand the mechanisms of spermatozoa movement. In this study, we described the composition of the seminal fluid (osmotic pressure, pH, and ions) and investigated the roles of these factors and salinity in initiating spermatozoa movement in the Pacific oyster. The acidic pH of the gonad (5.82 ± 0.22) maintained sperm in the quiescent stage and initiation of flagellar movement was triggered by a sudden increase of spermatozoa external pH (pHe) when released in seawater (SW). At pH 6.4, percentage of motile spermatozoa was three times higher when they were activated in SW containing 30 mM NH4Cl, which alkalinizes internal pH (pHi) of spermatozoa, compared to NH4Cl-free SW, revealing the role of pHi in triggering sperm movement. Percentage of motile spermatozoa activated in Na+-free artificial seawater (ASW) was highly reduced compared to ASW, suggesting that change of pHi triggering sperm motility was mediated by a Na+/H+ exchanger. Motility and swimming speed were highest in salinities between 33.8 and 42.7‰ (within a range of 0 to 50 ‰), and pH values above 7.5 (within a range of 4.5 to 9.5).

Continue reading ‘pH controls spermatozoa motility in the Pacific oyster (Crassostrea gigas)’

Warming and pCO2 effects on Florida stone crab larvae


• Elevated pCO2 reduced larval survivorship by 37%, but elevated temperature   had a greater effect reducing larval survival by 71%.
• Combined stressors reduced larval survivorship to megalopae by 80%.
• Larval morphology and ash free dry weight were not different among treatments.
•  Variability among broods suggests there is potential for adaptation within the species.


Greenhouse gas emissions are increasing ocean temperatures and the partial pressure of pCO2, resulting in more acidic waters. It is presently unknown how elevated temperature and pCO2 will influence the early life history stages of the majority of marine coastal species. We investigated the combined effect of elevated temperature (30 °C control and 32 °C treatment) and elevated pCO2 (450 μatm control and 1100 μatm treatment) on the (i) growth, (ii) survival, (iii) condition, and (iv) morphology of larvae of the commercially important Florida stone crab, Menippe mercenaria. At elevated temperature, larvae exhibited a significantly shorter molt stage, and elevated pCO2 caused stage-V larvae to delay metamorphosis to post-larvae. On average, elevated pCO2 resulted in a 37% decrease in survivorship relative to the control; however the effect of elevated temperature reduced larval survivorship by 71%. Exposure to both elevated temperature and pCO2 reduced larval survivorship by 80% relative to the control. Despite this, no significant differences were detected in the condition or morphology of stone crab larvae when subjected to elevated temperature and pCO2 treatments. Although elevated pCO2 could result in a reduction in larval supply, future increases in seawater temperatures are even more likely to threaten the future sustainability of the stone-crab fishery.

Continue reading ‘Warming and pCO2 effects on Florida stone crab larvae’

Ecological complexity buffers the impacts of future climate on marine consumers

Ecological complexity represents a network of interacting components that either propagate or counter the effects of environmental change on individuals and communities1,2,3. Yet, our understanding of the ecological imprint of ocean acidification (elevated CO2) and climate change (elevated temperature) is largely based on reports of negative effects on single species in simplified laboratory systems4,5. By combining a large mesocosm experiment with a global meta-analysis, we reveal the capacity of consumers (fish and crustaceans) to resist the impacts of elevated CO2. While individual behaviours were impaired by elevated CO2, consumers could restore their performances in more complex environments that allowed for compensatory processes. Consequently, consumers maintained key traits such as foraging, habitat selection and predator avoidance despite elevated CO2 and sustained their populations. Our observed increase in risk-taking under elevated temperature, however, predicts greater vulnerability of consumers to predation. Yet, CO2 as a resource boosted the biomass of consumers through species interactions and may stabilize communities by countering the negative effects of elevated temperature. We conclude that compensatory dynamics inherent in the complexity of nature can buffer the impacts of future climate on species and their communities.

Continue reading ‘Ecological complexity buffers the impacts of future climate on marine consumers’

Long-term exposure to acidification disrupts reproduction in a marine invertebrate

Climate change research is advancing to more complex and more comprehensive studies that include long-term experiments, multiple life-history stages, multi-population, and multi-trait approaches. We used a population of the barnacle Balanus improvisus known to be sensitive to short-term acidification to determine its potential for long-term acclimation to acidification. We reared laboratory-bred individuals (as singles or pairs), and field-collected assemblages of barnacles, at pH 8.1 and 7.5 (≈ 400 and 1600 μatm pCO2 respectively) for up to 16 months. Acidification caused strong mortality and reduced growth rates. Acidification suppressed respiration rates and induced a higher feeding activity of barnacles after 6 months, but this suppression of respiration rate was absent after 15 months. Laboratory-bred barnacles developed mature gonads only when they were held in pairs, but nonetheless failed to produce fertilized embryos. Field-collected barnacles reared in the laboratory for 8 months at the same pH’s developed mature gonads, but only those in pH 8.1 produced viable embryos and larvae. Because survivors of long-term acidification were not capable of reproducing, this demonstrates that B. improvisus can only partially acclimate to long-term acidification. This represents a clear and significant bottleneck in the ontogeny of this barnacle population that may limit its potential to persist in a future ocean.

Continue reading ‘Long-term exposure to acidification disrupts reproduction in a marine invertebrate’

No maternal or direct effects of ocean acidification on egg hatching in the Arctic copepod Calanus glacialis

Widespread ocean acidification (OA) is transforming the chemistry of the global ocean and the Arctic is recognised as the region where this transformation will occur at the fastest rate. Moreover, many Arctic species are considered less capable of tolerating OA due to their lower capacity for acid-base regulation. This inability may put severe restraints on many fundamental functions, such as growth and reproductive investments, which ultimately may result in reduced fitness. However, maternal effects may alleviate severe effects on the offspring rendering them more tolerant to OA. In a highly replicated experiment we studied maternal and direct effects of OA predicted for the Arctic shelf seas on egg hatching time and success in the keystone copepod species Calanus glacialis. We incubated females at present day conditions (pHT 8.0) and year 2100 extreme conditions (pHT 7.5) during oogenesis and subsequently reciprocally transplanted laid eggs between these two conditions. Statistical tests showed no effects of maternal or direct exposure to OA at this level. We hypothesise that Cglacialis may be physiologically adapted to egg production at low pH since oogenesis can also take place at conditions of potentially low haemolymph pH of the mother during hibernation in the deep.

Continue reading ‘No maternal or direct effects of ocean acidification on egg hatching in the Arctic copepod Calanus glacialis’

Transgenerational responses of a gammarid amphipod to ocean acidification: effects on reproductive traits, mate detection and metabolism

Ocean acidification (OA) poses a global threat to marine biodiversity. The rise in atmospheric carbon dioxide (CO2) concentration, resulting from anthropogenic activities, is responsible for the increase in the dissolved state of this gas in the oceans. The consequent changes in pH and seawater carbonate chemistry are responsible for the disruption of several biological processes (e.g. impairing survival and the maintenance of fitness-enhancing, physiological and behavioural, mechanisms) in certain marine groups. Disruption at the individual level, can originate negative cascading effects at higher levels of biological organization (i.e. populations and communities), which in turn can alter the underlying dynamics that control an ecosystem’s structure and overall function. Current theories suggest that marine organisms might be able to maintain their performance in future OA conditions, either through acclimation or through evolutionary adaptation. Surprisingly, the effects of prolonged high-CO2 exposure in crustaceans are still poorly known. The present dissertation investigates, for the first time, the transgenerational effects (i.e. over two generations) of ocean acidification in the physiology, behaviour (e.g. male mate-attraction) and reproductive traits (e.g. female investment, fecundity, mate-guarding and embryonic development) of the gammarid amphipod Gammarus locusta. Significant effects of ocean acidification were found for most reproductive traits. Although OA may initially stimulate female investment, transgenerational exposure led to an overall reduction in egg number and fecundity. The duration of mate-guarding behaviours was also diminished under high-CO2 exposure. Individuals from the second generation (F1) exhibited metabolic depression (i.e. reduced oxygen consumption rates), and males also displayed a reduced ability to accurately identify and track the origin of female scent cues, thus hinting at a possible disruption of chemosensory abilities. Overall, negative transgenerational (i.e. parental) effects were observed for all reproductive traits, as well as survival, in the acidified lineage. The present findings suggest that exposure to a future ocean acidification scenario will likely lead to a reduction in the fitness of the natural populations of G. locusta.

Continue reading ‘Transgenerational responses of a gammarid amphipod to ocean acidification: effects on reproductive traits, mate detection and metabolism’

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Ocean acidification in the IPCC AR5 WG II

OUP book