Ocean acidification (OA) is today considered one of the most pervasive stressors for marine biota at the level of species, communities and ecosystems. Naturally acidified systems, such as the CO2 vents, represent suitable laboratories to study the effects of OA on benthic organisms. An analysis of the colonization pattern of epibionts settled on artificial leaves (mimics) of Posidonia oceanica in relation to ocean acidification at the shallow CO2 vents off the island of Ischia, is here presented. Mimics of Posidonia oceanica artificial leaves (dark green flexible PVC stripes 1 cm wide x 36 cm long) were placed from September 2009 to September 2010 along a gradient of OA of the Ischia vent’s system at six stations (3 on the south and 3 on the north side of the study area), located at extreme low pH (mean pH 7.5), low pH (7.8), and control, normal pH conditions (8.12). Six artificial leaves per station were collected every three months and analysed for taxa identification and estimates of coverage (algae and sessile clonal invertebrates) and number of individuals (not clonal taxa). Patterns of colonization in control stations showed a progressive increase in time in coverage values of many organisms, mainly calcifying forms as coralline algae, which represent the dominant taxon, spirorbids and bryozoans. Colonization of artificial leaves located in low pH stations followed a similar temporal pattern as control conditions, but with lower coverage and higher patchiness of calcareous forms at 12 months of colonization. Epibionts in extreme low pH conditions were dominated by filamentous green/brown algae, with the occurrence of a few coralline algae, spirorbids and bryozoans, especially in the early months of colonization (3 and 6 months). Colonization at 9 and 12 months showed the disappearance of even these rare calcareous organisms and occurrence only of filamentous turf and fleshy algae, with a very simplified epibiont assemblage, remaining at an early, young colonization stage. These results indicate a strong selection of calcareous forms and the lack of successional stages in extreme low pH conditions, while the few calcifiers settled at short exposure time (3-6 months) do not seem to survive at longer exposure to critical values of OA.
Posts Tagged 'annelids'
Forever young… Colonization pattern of epibionts on Posidonia oceanica artificial leaves in relation to ocean acidification
Published 12 May 2015 Science ClosedTags: abundance, algae, annelids, biological response, BRcommunity, bryozoa, community composition, field, Mediterranean, otherprocess
Effects of low seawater pH on the marine polychaete Platynereis dumerilii
Published 4 May 2015 Science ClosedTags: annelids, biological response, laboratory, molecular biology, physiology
An important priority for any organism is to maintain internal cellular homeostasis including acid–base balance. Yet, the molecular level impacts of changing environmental conditions, such as low pH, remain uncharacterised. Herein, we isolate partial Na+/H+exchangers (NHE), carbonic anhydrase (CA), and calmodulin (CaM) genes from a polychaete, Platynereis dumerilii and investigate their relative expression in acidified seawater conditions. mRNA expression of NHE was significantly down-regulated after 1 h and up-regulated after 7 days under low pH treatment (pH 7.8), indicating changes in acid–base transport. Furthermore, the localisation of NHE expression was also altered. A trend of down regulation in CA after 1 h was also observed, suggesting a shift in the CO2 and HCO3− balance. No change in CaM expression was detected after 7 days exposure to acidified seawater. This study provides insight into the molecular level changes taking place following exposure to acidified seawater in a non-calcifying, ubiquitous, organism.
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Effects of seawater acidification on a coral reef meiofauna community
Published 27 April 2015 Science ClosedTags: abundance, annelids, biological response, BRcommunity, community composition, corals, crustaceans, laboratory, mesocosms, nematodes, otherprocess, platyhelminthes, South Atlantic, zooplankton
Despite the increasing risk that ocean acidification will modify benthic communities, great uncertainty remains about how this impact will affect the lower trophic levels, such as members of the meiofauna. A mesocosm experiment was conducted to investigate the effects of water acidification on a phytal meiofauna community from a coral reef. Community samples collected from the coral reef subtidal zone (Recife de Fora Municipal Marine Park, Porto Seguro, Bahia, Brazil), using artificial substrate units, were exposed to a control pH (ambient seawater) and to three levels of seawater acidification (pH reductions of 0.3, 0.6, and 0.9 units below ambient) and collected after 15 and 30 d. After 30 d of exposure, major changes in the structure of the meiofauna community were observed in response to reduced pH. The major meiofauna groups showed divergent responses to acidification. Harpacticoida and Polychaeta densities did not show significant differences due to pH. Nematoda, Ostracoda, Turbellaria, and Tardigrada exhibited their highest densities in low-pH treatments (especially at the pH reduction of 0.6 units, pH 7.5), while harpacticoid nauplii were strongly negatively affected by low pH. This community-based mesocosm study supports previous suggestions that ocean acidification induces important changes in the structure of marine benthic communities. Considering the importance of meiofauna in the food web of coral reef ecosystems, the results presented here demonstrate that the trophic functioning of coral reefs is seriously threatened by ocean acidification.
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Ocean acidification effects on stable isotope signatures and trophic interactions of polychaete consumers and organic matter sources at a CO2 shallow vent system
Published 20 April 2015 Science 4 CommentsTags: adaptation, algae, annelids, biogeochemistry, biological response, chemistry, field, Mediterranean, otherprocess, physiology
Stable carbon and nitrogen isotope analysis (SIA) was used to examine trophic interactions in a naturally acidified shallow coastal CO2 area in the Mediterranean Sea. SIA was helpful to determine the potential effects of ocean acidification (OA) on the interactions of organic matter sources and polychaete consumers, which appear to be tolerant to high pCO2. Mesoherbivore consumers, represented by three polychaete species, Platynereis dumerilii (Audouin and Milne Edwards, 1834) (Nereididae), Polyophthalmus pictus (Dujardin, 1839) (Opheliidae) and Syllis prolifera Krohn, 1852 (Syllidae), are abundant in the low pH conditions of the CO2 vents. Samples of consumers and potential organic matter sources (macroalgae, seagrass and epiphytes) were collected in two periods (May-June and Oct-Nov 2012) in two acidified areas (Castello Aragonese CO2 vents, off Ischia, Italy) and in two control areas. Results suggest a substantial effect of high pCO2 on isotopic composition of both organic matter sources and consumers. The recurring 13C depletion observed in the acidified sites is probably due to an increase in carbon availability and to the exploitation of volcanic-derived dissolved inorganic carbon (DIC) present in the area. The nutritional quality of organic matter sources was higher in low pH stations, where indeed C:N ratios decreased. Despite the occurrence of these effects, the trophic habit of high pCO2 tolerant polychaete consumers seems not to be dramatically affected. Our findings shed the light on how some benthic organisms may respond well to near-future OA conditions, exhibiting high plasticity also in their feeding habits, without being subject to dramatic ecological changes.
The effects of water acidification, temperature and salinity on the regenerative capacity of the polychaete Diopatra neapolitana
Published 6 March 2015 Science ClosedTags: annelids, biological response, laboratory, morphology, mortality, North Atlantic, performance
Changes in seawater pH, temperature and salinity are expected to occur in the near future, which can be a threat to aquatic systems, mainly for marine coastal areas, and their inhabiting species. Hence, the present study proposes to evaluate the effects of temperature shifts, pH decrease and salinity changes in the tissue’s regenerative capacity of the polychaete Diopatra neapolitana. This study evidenced that D. neapolitana individuals exposed to lower pH exhibited a significantly lower capacity to regenerate their body, while with the increase of temperature individuals showed a higher capacity to regenerate their tissues. Furthermore, the present work demonstrated that individuals exposed to salinities 28 and 35 did not present significant differences between them, while salinities 21 and 42 negatively influenced the regenerative capacity of D. neapolitana. At the end of regeneration, comparing all conditions, high salinity (42) seemed to have a greater impact on the regenerative capacity of individuals than the other factors, since under this condition individuals took longer to completely regenerate. Overall, this study demonstrated that variations in abiotic factors can strongly affect D. neapolitana’s performance.
Acidification effects on biofouling communities: winners and losers
Published 29 January 2015 Science ClosedTags: abundance, algae, annelids, biogeochemistry, biological response, BRcommunity, chordata, community composition, laboratory, molecular biology, morphology, North Atlantic, otherprocess, porifera
How ocean acidification affects marine life is a major concern for science and society. However, its impacts on encrusting biofouling communities, that are both the initial colonizers of hard substrata and of great economic importance, are almost unknown. We showed that community composition changed significantly, from 92% spirorbids, 3% ascidians and 4% sponges initially to 47% spirorbids, 23% ascidians and 29% sponges after 100 days in acidified conditions (pH 7.7). In low pH, numbers of the spirorbid Neodexiospira pseudocorrugata were reduced ×5 compared to controls. The two ascidians present behaved differently with Aplidium sp. decreasing ×10 in pH 7.7, whereas Molgula sp. numbers were ×4 higher in low pH than controls. Calcareous sponge (Leucosolenia sp.) numbers increased ×2.5 in pH 7.7 over controls. The diatom and filamentous algal community was also more poorly developed in the low pH treatments compared to controls. Colonization of new surfaces likewise showed large decreases in spirorbid numbers, but numbers of sponges and Molgula sp. increased. Spirorbid losses appeared due to both recruitment failure and loss of existing tubes. Spirorbid tubes are comprised of a loose prismatic fabric of calcite crystals. Loss of tube materials appeared due to changes in the binding matrix and not crystal dissolution, as SEM analyses showed crystal surfaces were not pitted or dissolved in low pH conditions. Biofouling communities face dramatic future changes with reductions in groups with hard exposed exoskeletons and domination by soft-bodied ascidians and sponges.
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Fabriciidae (Annelida, Sabellida) from a naturally acidified coastal system (Italy) with description of two new species
Published 30 December 2014 Media coverage ClosedTags: abundance, annelids, biological response, field, Mediterranean, otherprocess
Polychaete worms are known to thrive in extreme environmental conditions, however little is known about how polychaete species will respond to major climatic stressors, such as ocean acidification. Here, we examined the distribution of Fabriciidae (Annelida, Sabellida) species along a gradient of ocean acidification, caused by carbon dioxide (CO2) vent emissions in a shallow, coastal system off the island of Ischia (Tyrrhenian Sea, Italy). A total of 265 specimens of Fabriciidae, representing six species from five genera, were collected along the gradient. Most of the species were found across the entire CO2 gradient, suggesting polychaetes may have a high tolerance for ocean acidification in the future. Two of the species were new to science, and two of the genera were previously unrecorded in the Mediterranean. A full description of the new species Brifacia aragonensis sp. nov. andParafabricia mazzellae sp. nov. is given, both of which were most abundant in the most acidified areas (pH 6.6–7.2). The geographical distribution and ecology of the new taxa, as well as of the other fabriciid species collected, is discussed. Taxonomic keys to identify the Fabriciidae species currently recorded in the Mediterranean Sea are also provided.
Weakening mechanisms of the serpulid tube in a high CO2 world
Published 17 November 2014 Science ClosedTags: annelids, biological response, laboratory, morphology, performance
Many benthic marine organisms produce calcium carbonate (CaCO3) structures for mechanical protection through a biologically controlled calcification process. However, the oceans are becoming unfavorable for calcification because of the stress associated with ocean acidification (OA) and asscoaited chemical changes such as declining saturation state of CaCO3 and seawater pH. This work studies the impacts of OA driven decreased pH on the calcareous tubes produced by the serpulid tubeworm, Hydroides elegans. Tubes grown under control and OA experimental conditions were measured for structural and mechanical properties; and their mechanical properties were further interpreted using finite element analysis (FEA). The near-future predicted pH value of 7.8 altered tube ultrastructure, volume and density, and decreased the mean tube hardness and elasticity by ~80% and ~70%, respectively. The crushing force required for breaking the tube was reduced by 64%. The FEA results demonstrated how a simulated predator attack may alter structural and mechanical properties and consequently shift the stress development and distribution in the tubes, causing a more concentrated stress distribution; and therefore leading to a lower ability to withstand attacks.
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Benthic infaunal community structuring in an acidified tropical estuarine system
Published 11 November 2014 Science ClosedTags: abundance, annelids, biological response, BRcommunity, chemistry, community composition, crustaceans, field, otherprocess, South Pacific, zooplankton
Background
Recent studies suggest that increasing ocean acidification (OA) should have strong direct and indirect influences on marine invertebrates. While most theory and application for OA is based on relatively physically-stable oceanic ecological systems, less is known about the effects of acidification on nearshore and estuarine systems. Here, we investigated the structuring of a benthic infaunal community in a tropical estuarine system, along a steep salinity and pH gradient, arising largely from acid-sulphate groundwater inflows (Sungai Brunei Estuary, Borneo, July 2011- June 2012).
Results
Preliminary data indicate that sediment pore-water salinity (range: 8.07 – 29.6 psu) declined towards the mainland in correspondence with the above-sediment estuarine water salinity (range: 3.58 – 31.2 psu), whereas the pore-water pH (range: 6.47- 7.72) was generally lower and less variable than the estuarine water pH (range: 5.78- 8.3), along the estuary. Of the thirty six species (taxa) recorded, the polychaetes Neanthes sp., Onuphis conchylega, Nereididae sp. and the amphipod Corophiidae sp., were numerically dominant. Calcified microcrustaceans (e.g., Cyclopoida sp. and Corophiidae sp.) were abundant at all stations and there was no clear distinction in distribution pattern along the estuarine between calcified and non-calcified groups. Species richness increased seawards, though abundance (density) showed no distinct directional trend. Diversity indices were generally positively correlated (Spearman’s rank correlation) with salinity and pH (p <0.05) and negatively with clay and organic matter, except for evenness values (p >0.05). Three faunistic assemblages were distinguished: (1) nereid-cyclopoid-sabellid, (2) corophiid-capitellid and (3) onuphid- nereid-capitellid. These respectively associated with lower salinity/pH and a muddy bottom, low salinity/pH and a sandy bottom, and high salinity/pH and a sandy bottom. However, CCA suggested that species distribution and community structuring is more strongly influenced by sediment particle characteristics than by the chemical properties of the water (pH and salinity).
Conclusions
Infaunal estuarine communities, which are typically adapted to survive relatively acidic conditions, may be less exposed, less sensitive, and less vulnerable than epibenthic or pelagic communities to further acidification of above-sediment waters. These data question the extent to which all marine infaunal communities, including oceanic communities, are likely to be affected by future global CO2-driven acidification.
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Spatio-temporal variability of polychaete colonization at volcanic CO2 vents indicates high tolerance to ocean acidification
Published 30 October 2014 Science ClosedTags: abundance, annelids, biological response, field, Mediterranean, otherprocess
Ocean acidification is predicted to have negative effects on marine biota, resulting in the loss of biodiversity and changes in marine ecosystem structure and function. However, some species and life stages may be capable of thriving in low pH conditions, either due to their natural ability to tolerate stressful low pH–high pCO2 conditions and/or alteration of species interactions caused by changes in pH profiles, or due to evolutionary trade-offs. A better understanding of which species may be capable of tolerating ocean acidification can guide future research into the mechanisms for physiological and ecological resilience to future carbon dioxide (CO2) conditions. We investigated the colonization of selected polychaete species along a pH gradient originating from shallow, coastal volcanic CO2 vents (Ischia, Italy). Colonization was quantified by exposing artificial invertebrate collectors attached to the substratum for 30 days during different periods of the year (late spring, fall and late winter). Three species, Amphiglena mediterranea, Platynereis dumerilii and Syllis prolifera, were present and abundant along the gradient throughout the year. All three species were significantly more abundant in the most acidified areas, confirming their high tolerance and capacity to cope with very low pH. Abundances of all three species were compared to data previously collected via collectors suspended in the water column. More individuals were found in the collectors attached to the substratum, suggesting that abundances may have previously been underestimated. This is likely due to the close proximity of these collectors with the natural rocky substratum. All three species exhibited similar temporal variability, consistent with their life cycle and reproductive biology. Our results demonstrate high tolerance of the species for low and variable pH and corroborate their use as robust models to explore the capacity to cope with low pH–high pCO2 conditions, both in the natural vent systems and in the laboratory.
The impacts of ocean acidification on sperm swimming behaviour and fertilization success of key Australian marine invertebrates
Published 19 May 2014 Science ClosedTags: annelids, biological response, echinoderms, laboratory, performance, reproduction, South Pacific
Ocean acidification is increasingly threatening marine biodiversity. Marine organisms face intense selection pressure for phenotypes that are robust to rapidly acidifying oceans. Greater variability among phenotypes provides greater scope for selection. This variability is a central determinant of the capacity for adaptation, and – if traits that drive robustness are heritable – may ameliorate impacts of ocean acidification. Critical early life history stages possess few protective functions against changing environmental conditions, making broadcast spawning species particularly vulnerable. I explored the extent of inter- and intra-specific variation in responses of gametes to future ocean acidification across five sea urchin species and one polychaete species from Southeast Australia. Flow cytometry and sperm motility analyses were combined to investigate the relation between sperm swimming and mitochondrial function under ocean acidification. All species showed extensive between-male variability in sperm swimming responses to ocean acidification, but sperm of some species (Heliocidaris tuberculata, Tripneustes gratilla) were more robust than others Centrostephanus rodgersii,
Heliocidaris erythrogramma, Holopneustes purpurascens, Galeolaria caespitosa). Enhanced sperm swimming under acidified conditions in some males is likely to increase their reproductive success, supporting the concept of ‘winners’ and ‘losers’ of climate change at an individual level. Acidification-induced reductions in sperm mitochondrial activity in C. rodgersii were not reflected in similar reductions in sperm swimming behaviour. Collectively, these data suggest that capacity for selection of robust sperm phenotypes is present in all species, but that the adaptive benefits of this selection will depend on the degree of heritability of acidification-resistance traits. Shifts in the proportional contribution of robust vs susceptible males to offspring production may severely shift the genetic composition of subsequent generations, with flow-on consequences for species fitness and competitive ability. This may, in turn, alter competitive interactions between species and lead to species-dependent impacts on ecosystem structure and composition.
Settlement pattern of Posidonia oceanica epibionts along a gradient of ocean acidification: an approach with mimics
Published 24 March 2014 Science ClosedTags: abundance, algae, annelids, biological response, BRcommunity, bryozoa, chordata, cnidaria, community composition, crustaceans, field, Mediterranean, morphology, otherprocess, phanerogams, reproduction
Effects of ocean acidification (OA on the colonization/settlement pattern of the epibiont community of the leaves and rhizomesof the Mediterranean seagrass,Posidoniaoceanica, have been studied at volcanic CO2vents off Ischia (Italy), using “mimics”as artificial substrates. The experiments were conducted in shallowPosidoniastands (2-3 m depth), in three stations on the northand three on the south sides of the study area, distributed along a pH gradient. At each station, 4 rhizome mimics and 6 artificialleaves were collected every three months (Sept 2009-Sept 2010). The epibionts on both leaf and rhizome mimics showed clearchanges along the pH gradient; coralline algae and calcareous invertebrates (bryozoans, serpulid polychaetes and barnacles) weredominant at control stations but progressively disappeared at the most acidified stations. In these extremely low pH sites theassemblage was dominated by filamentous algae and non calcareous taxa such as hydroids and tunicates. Settlement pattern onthe artificial leaves and rhizome mimics over time showed a consistent distribution pattern along the pH gradient and highlightedthe peak of recruitment of the various organisms in different periods according to their life history.Posidoniamimics at theacidified station showed a poor and very simplified assemblage where calcifying epibionts seemed less competitive for space. Thisprofound difference in epiphyte communities in low pH conditions suggests cascading effects on the food web of the meadow and,consequently, on the functioning of the system.
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The path of most resilience
Published 23 January 2014 Science ClosedTags: adaptation, annelids, biological response, field, Mediterranean, molecular biology, morphology, physiology
Human activities are changing ecosystems around the world. Some species take these environmental changes in stride and are capable of surviving, or even thriving, in an altered landscape. However, other species are more sensitive, and decline or disappear. This variation in resilience to environmental change is a puzzle for scientists. Why there is such variation among species?
There are two possible paths to resilience in the face of environmental change. The first is for individuals to acclimatize, and alter their physiology so that they are better able to handle the new environment. The other path to resilience is through adaptation of the population, where only individuals that are suited to the altered environment survive and reproduce. So how do hardy species manage? Do they acclimatize or adapt?
Proteomic response of marine invertebrate larvae to ocean acidification and hypoxia during metamorphosis and calcification
Published 11 December 2013 Science ClosedTags: annelids, biological response, calcification, laboratory, multiple factors, otherprocess, oxygen, physiology
Calcifying marine invertebrates with complex life cycles are particularly at risk to climate changes as they undergo an abrupt ontogenetic shift during larval metamorphosis. Although our understanding of the larval response to climate changes is rapidly advancing, the proteome plasticity involved in a compensatory response to climate change is still unknown. In this study, we investigated the proteomic response of metamorphosing larvae of the tubeworm Hydroides elegans, challenged with two climate change stressors, ocean acidification (OA; pH 7.6) and hypoxia (HYP; 2.8 mg O2 l−1), and with both combined. Using a two-dimensional gel electrophoresis (2-DE)-based approach coupled with mass spectrometry, we found that climate change stressors did not affect metamorphosis except under OA, but altered the larval proteome and phosphorylation status. Metabolism and various stress and calcification-related proteins were downregulated in response to OA. In OA and HYP combined, HYP restored the expression of the calcification-related proteins to the control levels. We speculate that mild HYP stress could compensate for the negative effects of OA. This study also discusses the potential functions of selected proteins that might play important roles in larval acclimation and adaption to climate change.
Temperature dependent effects of elevated CO2 on shell composition and mechanical properties of hydroides elegans: insights from a multiple stressor experiment
Published 21 November 2013 Science ClosedTags: annelids, biological response, laboratory, morphology, multiple factors, North Pacific, salinity, temperature
The majority of marine benthic invertebrates protect themselves from predators by producing calcareous tubes or shells that have remarkable mechanical strength. An elevation of CO2 or a decrease in pH in the environment can reduce intracellular pH at the site of calcification and thus interfere with animal’s ability to accrete CaCO3. In nature, decreased pH in combination with stressors associated with climate change may result in the animal producing severely damaged and mechanically weak tubes. This study investigated how the interaction of environmental drivers affects production of calcareous tubes by the serpulid tubeworm, Hydroides elegans. In a factorial manipulative experiment, we analyzed the effects of pH (8.1 and 7.8), salinity (34 and 27‰), and temperature (23°C and 29°C) on the biomineral composition, ultrastructure and mechanical properties of the tubes. At an elevated temperature of 29°C, the tube calcite/aragonite ratio and Mg/Ca ratio were both increased, the Sr/Ca ratio was decreased, and the amorphous CaCO3 content was reduced. Notably, at elevated temperature with decreased pH and reduced salinity, the constructed tubes had a more compact ultrastructure with enhanced hardness and elasticity compared to decreased pH at ambient temperature. Thus, elevated temperature rescued the decreased pH-induced tube impairments. This indicates that tubeworms are likely to thrive in early subtropical summer climate. In the context of climate change, tubeworms could be resilient to the projected near-future decreased pH or salinity as long as surface seawater temperature rise at least by 4°C.
Sperm swimming in the polychaete Galeolaria caespitosa shows substantial inter-individual variability in response to future ocean acidification
Published 18 November 2013 Science ClosedTags: annelids, biological response, laboratory, reproduction, South Pacific
The rapidity of ocean acidification intensifies selection pressure for resilient phenotypes, particularly during sensitive early life stages. The scope for selection is greater in species with greater within-species variation in responses to changing environments, thus enhancing the potential for adaptation. We investigated among-male variation in sperm swimming responses (percent motility and swimming speeds) of the serpulid polychaete Galeolaria caespitosa to near- (ΔpH −0.3) and far-future ocean acidification (ΔpH −0.5). Responses of sperm swimming to acidification varied significantly among males and were overall negative. Robust sperm swimming behavior under near-future ocean acidification in some males may ameliorate climate change impacts, if traits associated with robustness are heritable, and thereby enhance the potential for adaptation to far-future conditions. Reduced sperm swimming in the majority of male G. caespitosa may decrease their fertilization success in a high CO2 future ocean. Resultant changes in offspring production could affect recruitment success and population fitness downstream.
Decreased pH does not alter metamorphosis but compromises juvenile calcification of the tube worm Hydroides elegans
Published 6 September 2013 Science ClosedTags: annelids, biological response, growth, laboratory, morphology, North Pacific, reproduction
Using CO2 perturbation experiments, we examined the pre- and post-settlement growth responses of a dominant biofouling tubeworm (Hydroides elegans) to a range of pH. In three different experiments, embryos were reared to, or past, metamorphosis in seawater equilibrated to CO2 values of about 480 (control), 980, 1,480, and 2,300 μatm resulting in pH values of around 8.1 (control), 7.9, 7.7, and 7.5, respectively. These three decreased pH conditions did not affect either embryo or larval development, but both larval calcification at the time of metamorphosis and early juvenile growth were adversely affected. During the 24-h settlement assay experiment, half of the metamorphosed larvae were unable to calcify tubes at pH 7.9 while almost no tubes were calcified at pH 7.7. Decreased ability to calcify at decreased pH may indicate that these calcifying tubeworms may be one of the highly threatened species in the future ocean.
Long-term effects of warming and ocean acidification are modified by seasonal variation in species responses and environmental conditions
Published 29 August 2013 Science ClosedTags: annelids, biological response, growth, multiple factors, performance, temperature
Warming of sea surface temperatures and alteration of ocean chemistry associated with anthropogenic increases in atmospheric carbon dioxide will have profound consequences for a broad range of species, but the potential for seasonal variation to modify species and ecosystem responses to these stressors has received little attention. Here, using the longest experiment to date (542 days), we investigate how the interactive effects of warming and ocean acidification affect the growth, behaviour and associated levels of ecosystem functioning (nutrient release) for a functionally important non-calcifying intertidal polychaete (Alitta virens) under seasonally changing conditions. We find that the effects of warming, ocean acidification and their interactions are not detectable in the short term, but manifest over time through changes in growth, bioturbation and bioirrigation behaviour that, in turn, affect nutrient generation. These changes are intimately linked to species responses to seasonal variations in environmental conditions (temperature and photoperiod) that, depending upon timing, can either exacerbate or buffer the long-term directional effects of climatic forcing. Taken together, our observations caution against over emphasizing the conclusions from short-term experiments and highlight the necessity to consider the temporal expression of complex system dynamics established over appropriate timescales when forecasting the likely ecological consequences of climatic forcing.
Adaptation and acclimatization to ocean acidification in marine ectotherms: an in situ transplant experiment with polychaetes at a shallow CO2 vent system
Published 26 August 2013 Science ClosedTags: adaptation, annelids, biological response, field, Mediterranean, molecular biology, morphology, physiology
Metabolic rate determines the physiological and life-history performances of ectotherms. Thus, the extent to which such rates are sensitive and plastic to environmental perturbation is central to an organism’s ability to function in a changing environment. Little is known of long-term metabolic plasticity and potential for metabolic adaptation in marine ectotherms exposed to elevated pCO2. Consequently, we carried out a series of in situ transplant experiments using a number of tolerant and sensitive polychaete species living around a natural CO2 vent system. Here, we show that a marine metazoan (i.e. Platynereis dumerilii) was able to adapt to chronic and elevated levels of pCO2. The vent population of P. dumerilii was physiologically and genetically different from nearby populations that experience low pCO2, as well as smaller in body size. By contrast, different populations of Amphiglena mediterranea showed marked physiological plasticity indicating that adaptation or acclimatization are both viable strategies for the successful colonization of elevated pCO2 environments. In addition, sensitive species showed either a reduced or increased metabolism when exposed acutely to elevated pCO2. Our findings may help explain, from a metabolic perspective, the occurrence of past mass extinction, as well as shed light on alternative pathways of resilience in species facing ongoing ocean acidification.
