Seaweeds are key species of the Baltic Sea benthic ecosystems. They are the substratum of numerous fouling epibionts like bryozoans and tubeworms. Several of these epibionts bear calcified structures and could be impacted by the high pCO2 events of the late summer upwellings in the Baltic nearshores. Those events are expected to increase in strength and duration with global change and ocean acidification. If calcifying epibionts are impacted by transient acidification as driven by upwelling events, their increasing prevalence could cause a shift of the fouling communities toward fleshy species. The aim of the present study was to test the sensitivity of selected seaweed macrofoulers to transient elevation of pCO2 in their natural microenvironment, i.e. the boundary layer covering the thallus surface of brown seaweeds. Fragments of the macroalga Fucus serratus bearing an epibiotic community composed of the calcifiers Spirorbis spirorbis (Annelida) and Electra pilosa (Bryozoa) and the non-calcifier Alcyonidium hirsutum (Bryozoa) were maintained for 30 days under three pCO2 conditions: natural 460±59 µatm, present-day upwelling1193±166 µatm and future upwelling 3150±446 µatm. Only the highest pCO2 caused a significant reduction of growth rates and settlement of S. spirorbis individuals. Additionally, S. spirorbis settled juveniles exhibited enhanced calcification of 40% during daylight hours compared to dark hours, possibly reflecting a day-night alternation of an acidification-modulating effect by algal photosynthesis as opposed to an acidification-enhancing effect of algal respiration. E. pilosa colonies showed significantly increased growth rates at intermediate pCO2 (1193 µatm) but no response to higher pCO2. No effect of acidification on A. hirsutum colonies growth rates was observed. The results suggest a remarkable resistance of the algal macro-epibionts to levels of acidification occurring at present day upwellings in the Baltic. Only extreme future upwelling conditions impacted the tubeworm S. spirorbis, but not the bryozoans.
Posts Tagged 'annelids'
Differential responses of calcifying and non-calcifying epibionts of a brown macroalga to present-day and future upwelling pCO2
Published 5 August 2013 Science ClosedTags: algae, annelids, Baltic, biological response, bryozoa, growth, laboratory, morphology, reproduction
Distribution of benthic marine invertebrates at northern latitudes ― an evaluation applying multi-algorithm species distribution models
Published 20 June 2013 Science ClosedTags: annelids, biological response, chemistry, cnidaria, crustaceans, field, multiple factors, North Atlantic
Different techniques of species distribution modeling were applied to evaluate the distribution of eight benthic marine species in Icelandic waters. The species examined were Symplectoscyphus tricuspidatus, Stegopoma plicatile (both Hydrozoa), Prionospio cirrifera, Amphicteis gunneri (both Polychaeta), Desmosoma strombergi, Eurycope producta (both Isopoda), Andaniella pectinata and Harpinia crenulata (both Amphipoda). Information on 13 environmental variables (temperature mean, temperature mean SD, temperature minimum, temperature maximum, salinity mean, salinity mean SD, oxygen content, particulate organic carbon, seasonal variation index, bottom roughness, sediment thickness, acidification) and records of occurrences of these eight species was collated in an ArcGIS project. Modeling methods applied were MARS, TreeNet, and MaxENT. According to Area under the receiver operating curve (AUC) model assessment values, models with moderate to outstanding discriminatory power were found for all species. There was a good overlap in the overall pattern of prediction for most species independent on the modeling technique. Among the three applied techniques MARS seemed to generalize most whereas TreeNet predictions very precisely reflected information from the training data set. The distribution of the selected benthic invertebrate species in Icelandic waters could be linked to a variety of environmental factors related to oceanography, seabed topography and human impact. Their multivariate interactions acted as a structuring force of species distribution, instead of just their one by one individual influence. The selected predictors varied between the different models for the same species. They substituted each other in different models. The expected distribution of the examined species was mapped for a seascape of known environmental settings. Such maps will serve as excellent references in future impact studies and enable the detection of changes in the distribution of benthic marine invertebrates.
Temperate reefs in a changing ocean: skeletal carbonate mineralogy of serpulids
Published 3 April 2013 Science ClosedTags: annelids, biological response, morphology, review
We present a review of the published data about serpulid skeletal carbonate geochemistry, augmented with new data from the Southern Hemisphere. We know something about skeletal carbonate mineralogy of 15 % of extant species (n = 52); and about half of extant genera (n = 25). Serpulid worm tubes vary in their skeletal mineralogy from entirely aragonitic (about 24 % of species) to entirely high-Mg calcite (40 %) to mixtures of the two. Mg in calcite ranges from 7 to 15 wt% MgCO3, with a mean of 11 wt% MgCO3. Little mineralogical variation within individuals or species can be found in aragonitic specimens, whereas high-Mg calcitic species show somewhat more variability in both calcite and Mg content, and those with mixed mineralogies are highly variable. These three groups correspond broadly with currently accepted clades. Given this strong phylogenetic signal, we analysed the data using phylogenetically independent contrasts, a statistical approach that separates genotypic from phenotypic variability; we found that variations which might be ascribed to environment were generally weak. The mineralogy of serpulid tubes makes them particularly vulnerable to ocean chemistry changes. While some serpulids appear to be able to adjust their tube mineralogy in order to adapt to sea-water chemistry, overall strength and elasticity may be sacrificed when they do. The biodiverse reef habitat provided by serpulids in some temperate regions may be the only complex solid habitat available, and loss or compromise of these temperate reefs will most likely have deleterious flow-on effects on temperate benthic communities.
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The response of abyssal organisms to low pH conditions during a series of CO2-release experiments simulating deep-sea carbon sequestration
Published 21 March 2013 Science ClosedTags: abundance, annelids, biological response, community composition, crustaceans, echinoderms, field, fish, mitigation, mollusks, nematodes, North Pacific, prokaryotes, survival
The effects of low-pH, high-pCO2 conditions on deep-sea organisms were examined during four deep-sea CO2 release experiments simulating deep-ocean C sequestration by the direct injection of CO2 into the deep sea. We examined the survival of common deep-sea, benthic organisms (microbes; macrofauna, dominated by Polychaeta, Nematoda, Crustacea, Mollusca; megafauna, Echinodermata, Mollusca, Pisces) exposed to low-pH waters emanating as a dissolution plume from pools of liquid carbon dioxide released on the seabed during four abyssal CO2-release experiments. Microbial abundance in deep-sea sediments was unchanged in one experiment, but increased under environmental hypercapnia during another, where the microbial assemblage may have benefited indirectly from the negative impact of low-pH conditions on other taxa. Lower abyssal metazoans exhibited low survival rates near CO2 pools. No urchins or holothurians survived during 30–42 days of exposure to episodic, but severe environmental hypercapnia during one experiment (E1; pH reduced by as much as ca. 1.4 units). These large pH reductions also caused 75% mortality for the deep-sea amphipod, Haploops lodo, near CO2 pools. Survival under smaller pH reductions (ΔpH<0.4 units) in other experiments (E2, E3, E5) was higher for all taxa, including echinoderms. Cephalopods, gastropods, and fish were more tolerant than most other taxa. The gastropod Mohnia vernalis and octopus Benthoctopus sp. survived exposure to pH reductions that episodically reached −0.3 pH units. Ninety percent of abyssal zoarcids (Pachycara bulbiceps) survived exposure to pH changes reaching ca. −0.3 pH units during 30–42 day-long experiments.
Mesozooplankton community development at elevated CO2 concentrations: results from a mesocosm experiment in an Arctic fjord (update)
Published 4 March 2013 Science ClosedTags: abundance, annelids, Arctic, biological response, community composition, crustaceans, field, mesocosms, mollusks, zooplankton
The increasing CO2 concentration in the atmosphere caused by burning fossil fuels leads to increasing pCO2 and decreasing pH in the world ocean. These changes may have severe consequences for marine biota, especially in cold-water ecosystems due to higher solubility of CO2. However, studies on the response of mesozooplankton communities to elevated CO2 are still lacking. In order to test whether abundance and taxonomic composition change with pCO2, we have sampled nine mesocosms, which were deployed in Kongsfjorden, an Arctic fjord at Svalbard, and were adjusted to eight CO2 concentrations, initially ranging from 185 μatm to 1420 μatm. Vertical net hauls were taken weekly over about one month with an Apstein net (55 μm mesh size) in all mesocosms and the surrounding fjord. In addition, sediment trap samples, taken every second day in the mesocosms, were analysed to account for losses due to vertical migration and mortality. The taxonomic analysis revealed that meroplanktonic larvae (Cirripedia, Polychaeta, Bivalvia, Gastropoda, and Decapoda) dominated in the mesocosms while copepods (Calanus spp., Oithona similis, Acartia longiremis and Microsetella norvegica) were found in lower abundances. In the fjord copepods prevailed for most of our study. With time, abundance and taxonomic composition developed similarly in all mesocosms and the pCO2 had no significant effect on the overall community structure. Also, we did not find significant relationships between the pCO2 level and the abundance of single taxa. Changes in heterogeneous communities are, however, difficult to detect, and the exposure to elevated pCO2 was relatively short. We therefore suggest that future mesocosm experiments should be run for longer periods.
The ecological effect of CO2 on the brown algae Fucus serratus and its epibionts: from the habitat to the organismic scale
Published 18 December 2012 Science ClosedTags: algae, annelids, Baltic, biological response, bryozoa, chemistry, field, growth, laboratory, photosynthesis, reproduction
Carbon dioxide plays a central role in the functioning of organisms and ecosystems. For autotrophs, it is the substrate for photosynthesis while for heterotrophs it is a waste product of respiration. For two centuries Human activities, are responsible for an increase from 280 to 380 μatm of the atmospheric pCO2. A further increase up to 1000 μatm is predicted for the 21th century. The ocean surface and the atmosphere are at the equilibrium for CO2. The CO2 dissolving in seawater reduces the pH and increase of corrosiveness of water for shells and skeletons made of calcium carbonates. Thus, this process of ocean acidification is expected to have detrimental effects on calcifying organism. On the contrary, marine autotrophs are supposed to (slightly) benefit from this extra supply of CO2. In this thesis, we aimed at assessing the influence of CO2 on members of the nearshore macrophytes meadows of the Baltic Sea, an ecosystem naturally exposed to elevated water acidity. In a first part, we investigated the natural variations of the carbonate system in a meadow during three weeks of July, August, and September 2011 in a sheltered bay of the Western Baltic. We observed important day night dynamics together with wider scale variations (days to weeks) of magnitude exceeding future climate change predictions. We were able to explain the variations by the action of light and wind speed and direction. Light drives the uptake and release of carbon by photosynthesis and respiration of the meadow and wind influences the upwelling of offshore hypercapnic seawater. In a second part, we investigated the growth response to elevated pCO2 of one of the main primary producer of the meadows, the brown algae Fucus serratus, in laboratory experiments. The algae were incubated under ambient pCO2, actual upwelling pCO2 and future upwelling pCO2. We observed an increase of growth of 20 % at the pCO2 expected for the year 2100 and up to 50 % at pCO2 possibly occurring during future upwelling events (4000 μatm). However, the effect was transient and a limitation of growth by nutrients occurred after about 20 days. In the third part, we tested the effect of at the same three pCO2 on the growth and recruitment of the main members of the sessile associated communities of Fucus serratus: the calcifying and non-calcifying bryozoan Electra pilosa and Alcyonidium hirsutum and the calcifying tubeworm Spirorbis spirorbis. We tested the hypothesis of greater sensitivity of calcifyers to acidification and found a resistance of all the tested organisms to the future ambient pCO2. In contrast, at the highest pCO2 tested (future upwelling), we observed in Spirorbis severe shell corrosion, reduction of growth and collapse of recruitment. The growth rates of the worm settlings were assessed at light and dark under the three experimental pCO2. A 40 % enhancement of growth was observed at light at any pCO2, possibly due to the algal photosynthetic reduction of pCO2 / increase of pH in the boundary layer surrounding the algal thallus. Our study illustrates the possibility of facilitation between species to resist ocean acidification.
Metal contamination increases the sensitivity of larvae but not gametes to ocean acidification in the polychaete Pomatoceros lamarckii (Quatrefages)
Published 29 October 2012 Science ClosedTags: annelids, biological response, laboratory, morphology, multiple factors, North Atlantic, reproduction, survival, toxicants
Ocean acidification is not happening in isolation but against a background of chronic low-level pollution for most coastal marine environments. The reproductive and larval stages of marine invertebrates can be highly sensitive to the impacts of both environmental pollutants and ocean acidification, but very little is currently known regarding the potential impacts of combined contaminant and high CO2 exposures on the health of marine organisms. Ocean acidification research to date has focused heavily on the responses of calcifying marine invertebrate larvae and algae, and as such the polychaetes as a group, despite their ecological importance, remain understudied. Here, we investigate the effects of elevated seawater CO2 (pH range 8.1–7.4, plus an extreme pH of 7.2 in the sperm motility experiments), in combination with the environmental pollutant copper (0.002 μM), on the early life history stages of the intertidal polychaete Pomatoceros lamarckii from two populations. P. lamarckii sperm appear to be robust to elevated seawater CO2. Whilst all three of the sperm motility end points measured showed a response to elevated CO2, these responses were small and not linear. The percentage of motile sperm and sperm curvilinear velocity were significantly reduced in the lower pH treatments of 7.4 and 7.2, whereas sperm straight-line velocity (VSL) was mostly unaffected except for an increased VSL at pH 8.0. Fertilisation success was investigated using two populations from the South West (UK), one from Torquay and one from Plymouth Sound. Fertilisation success was slightly but significantly reduced at the 7.6 and 7.4 pH treatments for both populations (a 9.0 % reduction in fertilisation success from pH 8.1 to 7.4 for Torquay), but with a greater effect observed in the population from Plymouth Sound (a 13.33 % reduction in fertilisation success). No additional impact of 0.002 μM copper exposure on fertilisation success was found. Larval survival was found to be much more sensitive to elevated CO2 than sperm function or fertilisation, and a significant interaction with copper exposure was observed. These results demonstrate the potential for polychaete larvae to be affected by predicted ocean acidification conditions and that chronic coastal pollutants, such as copper, have the potential to alter larval susceptibility to ocean acidification conditions.
Mesozooplankton community development at elevated CO2 concentrations: results from a mesocosm experiment in an Arctic fjord
Published 28 August 2012 Science ClosedTags: abundance, annelids, Arctic, biological response, BRcommunity, community composition, crustaceans, field, mesocosms, mollusks, zooplankton
The increasing CO2 concentration in the atmosphere caused by burning fossil fuels leads to increasing pCO2 and decreasing pH in the world oceans. These changes may have severe consequences for marine biota, especially in cold-water ecosystems due to higher solubility of CO2. However, studies on the response of mesozooplankton communities to elevated pCO2 are yet lacking. In order to test whether abundance and taxonomic composition change with pCO2, we have sampled nine mesocosms, which were deployed in Kongsfjorden, an Arctic fjord at Svalbard, and were adjusted to eight CO2 concentrations, initially ranging from 185 μatm to 1420 μatm. Samples were taken weekly over a six-week period with an Apstein net (55 μm mesh size) in all mesocosms and the surrounding fjord. In addition, sediment trap samples, taken every second day in the mesocosms, were analyzed to account for losses due to vertical migration and mortality. The taxonomic analysis revealed that meroplanktonic larvae (cirripeds, polychaetes, bivalves, gastropod, and decapods) dominated in the mesocosms while copepods (Calanus spp., Oithona similis, Acartia longiremis and Microsetella norvegica) were found in lower abundances. In the fjord copepods prevailed for most of our study. With time, abundance and taxonomic composition developed similarly in all mesocosms; the pCO2 had no significant effect on the overall community structure. However, single taxa responded to elevated CO2concentrations. The ratio of cirripedia nauplii to cypris larvae, the next developmental stage, in the sediment traps averaged over the entire experiment increased with pCO2 and this suggests that increased pCO2 may have delayed their development. Also, the number of bivalves, averaged over the experimental period, decreased significantly with increasing pCO2. The nature of the CO2 effect, either direct or indirect, remains open and needs to be addressed in future.
CO2-driven ocean acidification alters and weakens integrity of the calcareous tubes produced by the serpulid tubeworm, Hydroides elegans
Published 15 August 2012 Science ClosedTags: annelids, biological response, laboratory, morphology, North Pacific
As a consequence of anthropogenic CO2-driven ocean acidification (OA), coastal waters are becoming increasingly challenging for calcifiers due to reductions in saturation states of calcium carbonate (CaCO3) minerals. The response of calcification rate is one of the most frequently investigated symptoms of OA. However, OA may also result in poor quality calcareous products through impaired calcification processes despite there being no observed change in calcification rate. The mineralogy and ultrastructure of the calcareous products under OA conditions may be altered, resulting in changes to the mechanical properties of calcified structures. Here, the warm water biofouling tubeworm, Hydroides elegans, was reared from larva to early juvenile stage at the aragonite saturation state (ΩA) for the current pCO2 level (ambient) and those predicted for the years 2050, 2100 and 2300. Composition, ultrastructure and mechanical strength of the calcareous tubes produced by those early juvenile tubeworms were examined using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and nanoindentation. Juvenile tubes were composed primarily of the highly soluble CaCO3 mineral form, aragonite. Tubes produced in seawater with aragonite saturation states near or below one had significantly higher proportions of the crystalline precursor, amorphous calcium carbonate (ACC) and the calcite/aragonite ratio dramatically increased. These alterations in tube mineralogy resulted in a holistic deterioration of the tube hardness and elasticity. Thus, in conditions where ΩA is near or below one, the aragonite-producing juvenile tubeworms may no longer be able to maintain the integrity of their calcification products, and may result in reduced survivorship due to the weakened tube protection.
Predicted levels of future ocean acidification and temperature rise could alter community structure and biodiversity in marine benthic communities
Published 2 February 2011 Science ClosedTags: annelids, arthropoda, biological response, echinoderms, mollusks
A mesocosm experiment was conducted to quantify the effects of reduced pH and elevated temperature on an intact marine invertebrate community. Standardised faunal communities, collected from the extreme low intertidal zone using artificial substrate units, were exposed to one of eight nominal treatments (four pH levels: 8.0, 7.7, 7.3 and 6.7, crossed with two temperature levels: 12 and 16°C). After 60 days exposure communities showed significant changes in structure and lower diversity in response to reduced pH. The response to temperature was more complex. At higher pH levels (8.0 and 7.7) elevated temperature treatments contained higher species abundances and diversity than the lower temperature treatments. In contrast, at lower pH levels (7.3 and 6.7), elevated temperature treatments had lower species abundances and diversity than lower temperature treatments. The species losses responsible for these changes in community structure and diversity were not randomly distributed across the different phyla examined. Molluscs showed the greatest reduction in abundance and diversity in response to low pH and elevated temperature, whilst annelid abundance and diversity was mostly unaffected by low pH and was higher at the elevated temperature. The arthropod response was between these two extremes with moderately reduced abundance and diversity at low pH and elevated temperature. Nematode abundance increased in response to low pH and elevated temperature, probably due to the reduction of ecological constraints, such as predation and competition, caused by a decrease in macrofaunal abundance. This community-based mesocosm study supports previous suggestions, based on observations of direct physiological impacts, that ocean acidification induced changes in marine biodiversity will be driven by differential vulnerability within and between different taxonomical groups. This study also illustrates the importance of considering indirect effects that occur within multispecies assemblages when attempting to predict the consequences of ocean acidification and global warming on marine communities.
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The effect of CO2-induced ocean acidification on calcification rates and shell properties of two species of bimineralic marine calcifiers
Published 20 December 2010 Science ClosedTags: annelids, biological response, calcification, growth, laboratory, mollusks
Two-month laboratory experiments were conducted to investigate the effect of CO2-induced reductions in seawater CaCO3 saturation state on the calcification rate and skeletal properties of two bimineralic species of marine calcifiers: the serpulid tube worm Hydroides crucigera and the whelk Urosalpinx cinerea. The CaCO3 saturation states of the experimental seawaters, constrained by intercalibrated determinations of pH, alkalinity, and DIC, were attained with bubbled air-CO2 mixtures of 400 (ambient), 600, 900, and 2850 ppm pCO2, yielding Ω-aragonite of 2.5 (ambient), 2.0, 1.5, and 0.7, respectively. The organisms investigated in the present study accrete bimineralic shells of layered aragonite and calcite (whelk = low-Mg calcite; serpulid worm tube = high-Mg calcite). Buoyant weighing of the organisms at the beginning and end of the experiment revealed that their net rates of calcification decreased with increasing pCO2. A Ba-137 isotope spike added to the seawater and incorporated into the shell at the start of the experiment revealed that both species continued accreting new shell material along their zones of calcification under each of the 4 pCO2 treatments. However, linear extension rates measured relative to the Ba-137 spike declined with increasing pCO2. Powder X-ray diffraction (XRD) of the organisms’ bimineralic shells revealed increasing calcite:aragonite ratios with increasing pCO2. Synchrotron micro-XRD also revealed that the micron-scale distribution of calcite and aragonite within the shells of both organisms varied as a function of pCO2. Calcite Mg/Ca ratios, inferred from d-spacing of the calcite crystal lattice, increased with pCO2 for the high-Mg-calcite-accreting serpulid worms, yet were unaffected for the low-Mg-calcite-accreting whelks. Scanning electron microscopy (SEM) of the shells of both organisms revealed evidence of dissolution of the more soluble CaCO3 phases under the highest pCO2 treatment (2850 ppm). SEM images also revealed that CaCO3 crystal geometry and habit varied with pCO2. Biomechanical tests of the organisms’ shells revealed a decrease in both hardness and fracture resistance with increasing pCO2, which is likely attributable to partial dissolution of the more soluble phases of the organisms’ shells and/or changes in the geometry and habit of the shells’ constituent crystals. Most calcareous marine invertebrates and algae are thought to have evolved calcareous shells, tests, and skeletons to deter predation. Layered bimineralic shells, such as those produced by the whelk and serpulid worm investigated here, are thought to confer additional protection by interrupting crack-propagation and by dispersing loads throughout a more heterogeneous and complex matrix, which should effectively dissipate and/or dampen external forces. This work reveals that CO2-induced reduction in the CaCO3 saturation state of seawater not only reduces the rate at which these organisms accrete their protective shells, but also that it compromises the unique biomechanical properties of their layered bimineralic shells.
Effects of ocean acidification on invertebrate settlement at volcanic CO2 vents
Published 2 August 2010 Science ClosedTags: annelids, biological response, crustaceans, field, Mediterranean, mollusks, nematodes, protists
We present the first study of the effects of ocean acidification on settlement of benthic invertebrates and microfauna. Artificial collectors were placed for 1 month along pH gradients at CO2 vents off Ischia (Tyrrhenian Sea, Italy). Seventy-nine taxa were identified from six main taxonomic groups (foraminiferans, nematodes, polychaetes, molluscs, crustaceans and chaetognaths). Calcareous foraminiferans, serpulid polychaetes, gastropods and bivalves showed highly significant reductions in recruitment to the collectors as pCO2 rose from normal (336–341 ppm, pH 8.09–8.15) to high levels (886–5,148 ppm) causing acidified conditions near the vents (pH 7.08–7.79). Only the syllid polychaete Syllis prolifera had higher abundances at the most acidified station, although a wide range of polychaetes and small crustaceans was able to settle and survive under these conditions. A few taxa (Amphiglena mediterranea, Leptochelia dubia, Caprella acanthifera) were particularly abundant at stations acidified by intermediate amounts of CO2 (pH 7.41–7.99). These results show that increased levels of CO2 can profoundly affect the settlement of a wide range of benthic organisms.
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