Trans-generational plasticity (TGP) represents a primary mechanism for guaranteeing species persistence under rapid global changes. To date, no study on TGP responses of marine organisms to global change scenarios in the ocean has been conducted on phylogenetically closely related species, and we thus lack a true appreciation for TGP inter-species variation. Consequently, we examined the tolerance and TGP of life-history and physiological traits in two annelid species within the genus Ophryotrocha: one rare (O. robusta) and one common (O. japonica). Both species were exposed over two generations to ocean acidification (OA) and warming (OW) in isolation and in combination (OAW). Warming scenarios led to a decrease in energy production together with an increase in energy requirements, which was lethal for O. robusta before viable offspring could be produced by the F1. Under OA conditions, O. robusta was able to reach the second generation, despite showing lower survival and reproductive performance when compared to control conditions. This was accompanied by a marked increase in fecundity and egg volume in F2 females, suggesting high capacity for TGP under OA. In contrast, O. japonica thrived under all scenarios across both generations, maintaining its fitness levels via adjusting its metabolomic profile. Overall, the two species investigated show a great deal of difference in their ability to tolerate and respond via TGP to future global changes. We emphasize the potential implications this can have for the determination of extinction risk, and consequently, the conservation of phylogenetically closely related species.
Posts Tagged 'annelids'
Within- and trans-generational responses to combined global changes are highly divergent in two congeneric species of marine annelids
Published 13 March 2020 Science ClosedTags: annelids, biological response, growth, laboratory, Mediterranean, morphology, mortality, multiple factors, physiology, reproduction, temperature
Cascading effects of climate change on plankton community structure
Published 26 February 2020 Science ClosedTags: abundance, algae, annelids, biological response, BRcommunity, communityMF, crustaceans, laboratory, multiple factors, North Atlantic, otherprocess, phytoplankton, review, temperature, zooplankton
Plankton communities account for at least half of global primary production and play a key role in the global carbon cycle. Warming and acidification may alter the interaction chains in these communities from the bottom and top of the food web. Yet, the relative importance of these potentially complex interactions has not yet been quantified. Here, we examine the isolated and combined effects of warming, acidification, and reductions in phytoplankton and predator abundances in a series of factorial experiments. We find that warming directly impacts the top of the food web, but that the intermediate trophic groups are more strongly influenced by indirect effects mediated by altered top-down interactions. Direct manipulations of predator and phytoplankton abundance reveal similar strong top-down interactions following top predator decline. A meta-analysis of published experiments further supports the conclusion that warming has stronger direct impacts on the top and bottom of the food web rather than the intermediate trophic groups, with important differences between freshwater and marine plankton communities. Our results reveal that the trophic effect of warming cascading down from the top of the plankton food web is a powerful agent of global change.
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Regulation of calcification site pH is a polyphyletic but not always governing response to ocean acidification
Published 30 January 2020 Science ClosedTags: annelids, biogeochemistry, biological response, calcification, corals, crustaceans, echinoderms, laboratory, mollusks, physiology
The response of marine-calcifying organisms to ocean acidification (OA) is highly variable, although the mechanisms behind this variability are not well understood. Here, we use the boron isotopic composition (δ11B) of biogenic calcium carbonate to investigate the extent to which organisms’ ability to regulate pH at their site of calcification (pHCF) determines their calcification responses to OA. We report comparative δ11B analyses of 10 species with divergent calcification responses (positive, parabolic, threshold, and negative) to OA. Although the pHCF is closely coupled to calcification responses only in 3 of the 10 species, all 10 species elevate pHCF above pHsw under elevated pCO2. This result suggests that these species may expend additional energy regulating pHCF under future OA. This strategy of elevating pHCF above pHsw appears to be a polyphyletic, if not universal, response to OA among marine calcifiers—although not always the principal factor governing a species’ response to OA.
Clam feeding plasticity reduces herbivore vulnerability to ocean warming and acidification
Published 22 January 2020 Science ClosedTags: abundance, algae, annelids, biological response, BRcommunity, community composition, communitymodeling, laboratory, modeling, mollusks, multiple factors, North Atlantic, otherprocess, performance, phytoplankton, temperature
Ocean warming and acidification affect species populations, but how interactions within communities are affected and how this translates into ecosystem functioning and resilience remain poorly understood. Here we demonstrate that experimental ocean warming and acidification significantly alters the interaction network among porewater nutrients, primary producers, herbivores and burrowing invertebrates in a seafloor sediment community, and is linked to behavioural plasticity in the clam Scrobicularia plana. Warming and acidification induced a shift in the clam’s feeding mode from predominantly suspension feeding under ambient conditions to deposit feeding with cascading effects on nutrient supply to primary producers. Surface-dwelling invertebrates were more tolerant to warming and acidification in the presence of S. plana, most probably due to the stimulatory effect of the clam on their microalgal food resources. This study demonstrates that predictions of population resilience to climate change require consideration of non-lethal effects such as behavioural changes of key species.
The effect of elevated CO2 on the production and respiration of a Sargassum thunbergii community: a mesocosm study
Published 11 December 2019 Science ClosedTags: abundance, algae, annelids, biological response, BRcommunity, community composition, crustaceans, field, laboratory, mesocosms, mollusks, North Pacific, otherprocess, photosynthesis, primary production, zooplankton
Approximately one‐third of anthropogenic carbon dioxide is absorbed into the ocean and causes it to become more acidic. The Intergovernmental Panel on Climate Change (IPCC) suggested that the surface ocean pH, by the year 2100, would drop by a further 0.3 and 0.4 pH units under RCP (Representative Concentration Pathway) 6.0 and 8.5 climate scenarios. The macroalgae communities that consisted of Sargassum thunbergii and naturally attached epibionts were exposed to fluctuations of ambient and manipulated pH (0.3–0.4 units below ambient pH). The production and respiration in S. thunbergii communities were calculated from dissolved oxygen time‐series recorded with optical dissolved oxygen sensors. The pH, irradiance, and dissolved oxygen occurred in parallel with diurnal (day/night) patterns. According to net mesocosm production – photosynthetically active radiation (PAR) model, the saturation and compensation PAR, the mean maximum gross mesocosm production (GMP), and daily mesocosm respiration were higher in the CO2 enrichment, than in the ambient condition, while the mean of photosynthetic coefficient was similar. In conclusion, elevated CO2 stimulated oxygen production and consumption of S. thunbergii communities in the mesocosm. Furthermore, the sensitivity of the GMP of the S. thunbergii community to irradiance was reduced, and achieved maximum production rate at higher PAR. These positive responses to CO2 enrichment suggest that S. thunbergii communities may thrive in under high CO2 conditions.
Behavioral responses to ocean acidification in marine invertebrates: new insights and future directions
Published 2 December 2019 Science ClosedTags: annelids, biological response, bryozoa, cnidaria, crustaceans, echinoderms, mollusks, review
Ocean acidification (OA) affects marine biodiversity and alters the structure and function of marine populations, communities, and ecosystems. Recently, effects of OA on the behavioral responses of marine animals have been given with much attention. While many of previous studies focuses on marine fish. Evidence suggests that marine invertebrate behaviors were also be affected. In this review, we discussed the effects of C02-driven OA on the most common behaviors studied in marine invertebrates, including settlement and habitat selection, feeding, anti-predatory, and swimming behaviors, and explored the related mechanisms behind behaviors. This review summarizes how OA affects marine invertebrate behavior, and provides new insights and highlights novel areas for future research.
Recoverable impacts of ocean acidification on the tubeworm, Hydroides elegans: implication for biofouling in future coastal oceans
Published 22 November 2019 Science ClosedTags: annelids, biological response, growth, laboratory, morphology, North Pacific
Ocean uptake of anthropogenic CO2 causes ocean acidification (OA), which not only decreases the calcification rate, but also impairs the formation of calcareous shells or tubes in marine invertebrates such as the dominant biofouling tubeworm species, Hydroides elegans. This study examined the ability of tubeworms to resume normal tube calcification when returned to ambient pH 8.1 from a projected near-future OA level of pH 7.8. Tubeworms produced structurally impaired and mechanically weaker calcareous tubes at pH 7.8 compared to at pH 8.1, but were able to recover when the pH was restored to ambient levels. This suggests that tubeworms can physiologically recover from the impacts of OA on tube calcification, composition, density, hardness and stiffness when returned to optimal conditions. These results help understanding of the progression of biofouling communities dominated by tubeworms in future oceans with low pH induced by OA.
Influence of physico-chemical parameters and pCO2 concentration on mangroves-associated polychaetes at Pichavaram, southeast coast of India
Published 11 November 2019 Science ClosedTags: annelids, biological response, BRcommunity, chemistry, field, Indian
Studies related to partial pressure of carbon dioxide (pCO2) concentration linking with polychaete diversity in mangrove ecosystems are limited in time and space. Therefore, the present study was conducted during July 2017–June 2018 on a monthly interval and reported the concentration of pCO2 coupled with physico-chemical parameters in relation to polychaetes diversity in Pichavaram mangroves ecosystem, southeast coast of India. Totally, 41 species were identified and the most dominant species were Prionospio cirrifera, P. cirrobranchiata, P. sexoculata, Prionospio sp. and Capitella capitata. Among the stations, higher polychaete diversity was found in marine zone compared to other zones. The correlation reflected a significant positive linear relationship between dissolved inorganic carbon (DIC), dissolved organic carbon (DOC), particulate organic carbon (POC) and CO2 versus pCO2. The carbon species DIC, DOC, POC and pCO2 concentration ranged from 1100.1 to 2053.3(µmol/kg), 165.7–1954.0(µmol/kg), 4.5–89.2(µmol/kg) and 184.7–3763.1(µatm), respectively. Further, the statistical analyses revealed that there was a strong correlation among carbon species with distribution of polychaete species in various zones of mangroves and thus indicating pivotal role in occurrence of polychaetes in mangroves.
Epibenthic community variation along an acidified tropical estuarine system
Published 22 October 2019 Science ClosedTags: abundance, annelids, biological response, BRcommunity, community composition, field, mollusks, North Pacific, otherprocess
The benthic communities associated with hard substrata in tropical estuaries (rocky surfaces and mangrove roots) are underexplored compared to sediment-associated communities. Being unaffected by within-sediment chemistry, rocky surface communities are exposed to water-column chemistry. Natural and anthropogenic acidic inflows into estuaries are common, yet understanding of how low pH estuarine water impacts communities is limited. This study investigated variation in a rocky substratum benthic community along a steep pH and carbonate saturation gradient in a tropical estuary. Samples (n=72) samples were collected from four stations in the Brunei estuarine system, South East Asia (pH 5.78 – 8.1, salinity 0.1 – 29.5 psu). Species richness, diversity and abundance were greatest at the seaward end of the estuary (where pH and salinity were high), reduced in the middle estuary, and relatively high again in the upper estuary. A total of 34 species were recorded, with station abundances varying between 95 and 336 individuals/100 cm2. At a coarse taxonomic level (class/order), multivariate analyses revealed three distinct communities, a tanaid–polychaete dominated community, a mussel–dipteran community, and a mussel–amphipod–dipteran community. The observed shift from amphipod-dominance to polychaete-dominance along a decreasing pH gradient is consistent with the community changes seen in open ocean systems influenced by elevated pCO2. This study is the first description of community structure variation for hard-substratum invertebrates in an old-world tropical estuary. It shows that acidified estuaries offer insights into community-level responses to marine acidification in general.
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Stress across life stages: impacts, responses and consequences for marine organisms
Published 15 October 2019 Science ClosedTags: annelids, biological response, BRcommunity, laboratory, morphology, multiple factors, oxygen, performance, reproduction, review
Highlights
• The published data were analysed to assess carry-over effects on marine organisms.
• The capacity of larvae to recover from early starvation and hypoxia was tested.
• Food limitation is the main driver of negative carry-over effects on juvenile growth.
• Larvae can recover from the early stress without negative imprints as juveniles.
• Carry-over effects depend on the duration of stress relative to larval period.
Abstract
Population dynamics of marine organisms are strongly driven by their survival in early life stages. As life stages are tightly linked, environmental stress experienced by organisms in the early life stage can worsen their performance in the subsequent life stage (i.e. carry-over effect). However, stressful events can be ephemeral and hence organisms may be able to counter the harmful effects of transient stress. Here, we analysed the published data to examine the relative strength of carry-over effects on the juvenile growth of marine organisms, caused by different stressors (hypoxia, salinity, starvation, ocean acidification and stress-induced delayed metamorphosis) experienced in their larval stage. Based on 31 relevant published studies, we revealed that food limitation had the greatest negative carry-over effect on juvenile growth. In the laboratory, we tested the effects of short-term early starvation and hypoxia on the larval growth and development of a model organism, polychaete Hydroides elegans, and assessed whether the larvae can accommodate the early stress to maintain their performance as juveniles (settlement and juvenile growth). Results showed that early starvation for 3 days (∼50% of normal larval period) retarded larval growth and development, leading to subsequent reduced settlement rate and juvenile growth. When the starvation period decreased to 1 day, however, the larvae could recover from early starvation through compensatory growth and performed normal as juveniles (c.f. control). Early exposure to hypoxia did not affect larval growth (body length) and juvenile growth (tube length), but caused malformation of larvae and reduced settlement rate. We conclude that the adverse effects of transient stress can be carried across life stages, but depend on the duration of stressful events relative to larval period. As carry-over effects are primarily driven by energy acquisition, how food availability varies over time and space is fundamental to the population dynamics of marine organisms.
Future ocean climate homogenizes communities across habitats through diversity loss and rise of generalist species
Published 16 July 2019 Science ClosedTags: abundance, algae, annelids, biological response, BRcommunity, chordata, community composition, field, mesocosms, multiple factors, nematodes, otherprocess, porifera, South Pacific, temperature, zooplankton
Predictions of the effects of global change on ecological communities are largely based on single habitats. Yet in nature, habitats are interconnected through the exchange of energy and organisms, and the responses of local communities may not extend to emerging community networks (i.e. metacommunities). Using large mesocosms and meiofauna communities as a model system, we investigated the interactive effects of ocean warming and acidification on the structure of marine metacommunities from three shallow‐water habitats: sandy soft‐bottoms, marine vegetation and rocky reef substrates. Primary producers and detritus – key food sources for meiofauna – increased in biomass under the combined effect of temperature and acidification. The enhanced bottom‐up forcing boosted nematode densities but impoverished the functional and trophic diversity of nematode metacommunities. The combined climate stressors further homogenized meiofauna communities across habitats. Under present‐day conditions metacommunities were structured by habitat type, but under future conditions they showed an unstructured random pattern with fast‐growing generalist species dominating the communities of all habitats. Homogenization was likely driven by local species extinctions, reducing interspecific competition that otherwise could have prevented single species from dominating multiple niches. Our findings reveal that climate change may simplify metacommunity structure and prompt biodiversity loss, which may affect the biological organization and resilience of marine communities.
Ocean acidification affects calcareous tube growth in adult stage and reared offspring of serpulid polychaetes
Published 19 June 2019 Science ClosedTags: annelids, biological response, dissolution, growth, laboratory, Mediterranean, morphology, reproduction
The energetically costly transition from free-swimming larvae to benthic life stage and maintenance of a calcareous structure can make calcifying marine invertebrates vulnerable to ocean acidification. The first goal of this study was to evaluate the impacts of ocean acidification on calcified tube growth for two Serpulidae polychaete worms. Spirorbis sp. and Spirobranchus triqueter were collected at 11 m depth from the Northwest Mediterranean Sea and maintained for 30 and 90 d, at three mean pHT levels (total scale) of 8.1 (ambient), 7.7, and 7.4. Moderately decreased tube elongation rates were observed in both species at a pHT of 7.7 while severe reductions occurred at pHT 7.4. There was visual evidence of dissolution and tubes were more fragile at lower pH but, fragility was not attributed to changes in fracture toughness. Instead, it appeared to be due to the presence of larger alveoli covered in a thinner calcareous layer. The second objective of the study was to test for effects in offspring development of the species S. triqueter. Spawning was induced, and offspring were reared in the same pH conditions the parents experienced. Trochophore size was reduced at the lowest pH level but settlement success was similar across pH conditions. Post-settlement tube growth was most affected. At 38 d post-settlement, juvenile tubes at pHT of 7.7 and 7.4 were half the size of those at pHT 8.1. Results suggest future carbonate chemistry will negatively affect initiation and persistence of both biofouling and epiphytic polychaete tube worms.
Multiple stressor effects on macrobenthic communities in Corpus Christi Bay, Texas, U.S.A.
Published 2 May 2019 Science ClosedTags: abundance, annelids, BRcommunity, crustaceans, field, mollusks, morphology, North Atlantic, otherprocess
At any moment in nature, organisms are likely being exposed to multiple stressors, the effects of which are difficult to separate. Often, however, environmental stressors are considered on an individual basis. In southeastern Corpus Christi Bay, TX, declines in benthic macrofaunal community abundance, biomass, diversity, species richness, and species evenness have largely been attributed to the occurrence of hypoxia, a condition of low dissolved oxygen (DO). This study proposes that multiple stressors contribute to these observed benthic macrofaunal declines in southeastern Corpus Christi Bay. Therefore, a 30-year time series of water quality data (salinity, temperature, DO, pH, phosphate, ammonium, nitrite+nitrate, sulfate) and benthic community data (abundance, biomass, species richness, species evenness) was analyzed to describe 1) water quality dynamics of the region and 2) relationships between water quality dynamics and benthic macrofaunal response. Principal component analysis indicated that a large variability in the water quality dataset (63%) could be summarized by three principal components representing a multiple stressor index, a nutrient index, and an acidification index. Seasonality was found to be confounded with the multiple stressor index but not the nutrient or acidification indexes. Spearman rank-order correlations indicated both the multiple stressor and acidification indexes were inversely related to benthic macrofaunal community abundance, biomass, and species richness. A stepwise multiple linear regression analysis on individual water quality variables specified DO, and possibly temperature, to be leading explanatory variables for predicting benthic abundance. Temperature, pH, and nitrite+nitrate were indicated as leading explanatory variables for predicting benthic biomass. Temperature was indicated to be the only leading explanatory variable for predicting species richness. Results demonstrate that multiple stressors, including high temperature, high salinity, and low DO concentrations, are collectively acting on benthic communities in southeastern Corpus Christi Bay.
The influence of simulated global ocean acidification on the toxic effects of carbon nanoparticles on polychaetes
Published 12 February 2019 Science ClosedTags: annelids, biological response, laboratory, otherprocess, physiology
Highlights
• Slighter aggregation and more suspended carbon nanomaterials in acidified seawater
• Under pH acidified both carbon nanomaterials generated greater oxidative stress in polychaetes.
• Functionalized carbon nanomaterials increased oxidative stress and neurotoxicity under both pHs.
• Ocean acidification may cause a higher risk of carbon nanomaterials to marine ecosystems.
Abstract
Ocean acidification events are recognized as important drivers of change in biological systems. Particularlly, the impacts of estuarine acidification are severe than surface ocean due to its shallowness, low buffering capacity, low salinity and high organic matter from land drainage. Moreover, because they are transitional areas, estuaries can be seriously impacted by any number of anthropogenic activities and in the last decades, carbon nanomaterials (CNMs) are considered as emerging contaminants in the estuarine ecosystem. Considering all these evidences, chronic experiment was carried out trying to understand the possible alteration on the chemical behaviour of two different CNMs (functionalized and pristine) in predicted climate change scenarios and consequently, how these alterations could modify the sensitivity of one the most common marine and estuarine organisms (the polychaeta Hediste diversicolor) assessing a set of biomarkers related to polychaetes oxidative status as well as the metabolic performance and neurotoxicity. Our results demonstrated that all enzymes worked together to counteract seawater acidification and CNMs, however oxidative stress in the exposed polychaetes to both CNMs, especially under ocean acidification conditions was enhanced. In fact, although the antioxidant enzymes tried to cope as compensatory response of cellular defense systems against oxidative stress, the synergistic interactive effects of pH and functionalized CNMs indicated that acidified pH significantly increased the oxidative damage (in terms of lipid peroxidation) in the cotaminated organisms. Different responses were observed in organisms submitted to pristine CNMs under pH control, where the lipid peroxidation did not increase along with the increasing exposure concentrations. The present results further demonstrated the neurotoxicity caused by both CNMs, especially noticeable at acidified conditions. The mechanism of enhanced toxicity could be attributed to slighter aggregation and more suspended NMs in acidified seawater (demonstrated in the DLS analysis). Therefore, ocean acidification may cause a higher risk of CNMs to marine ecosystems.
Effects of short-term and long-term exposure to ocean acidification on carbonic anhydrase activity and morphometric characteristics in the invasive polychaete Branchiomma boholense (Annelida: Sabellidae): a case-study from a CO2 vent system
Published 30 January 2019 Science ClosedTags: annelids, biological response, field, Mediterranean, morphology, physiology, vents
Highlights
• Carbonic anhydrase activity remained unchanged after 30-days exposure to high pCO2.
• A significant decrease in weight was observed under short-term acclimatization to low pH.
• Enzyme activity and protein content showed a 50% increase under chronic exposure to OA.
• A significant variation in wet weight was detected under long-term exposure to low pH.
Abstract
The aim of this study was to test the effects of short- and long-term exposure to high pCO2 on the invasive polychaete Branchiomma boholense (Grube, 1878), (Sabellidae), through the implementation of a transplant experiment at the CO2 vents of the Castello Aragonese at the island of Ischia (Italy). Analysis of carbonic anhydrase (CA) activity, protein tissue content and morphometric characteristics were performed on transplanted individuals (short-term exposure) as well as on specimens resident to both normal and low pH/high pCO2 environments (long-term exposure). Results obtained on transplanted worms showed no significant differences in CA activity between individuals exposed to control and acidified conditions, while a decrease in weight was observed under short-term acclimatization to both control and low pH, although at low pH the decrease was more pronounced (∼20%). As regard individuals living under chronic exposure to high pCO2, the morphometric results revealed a significantly lower (70%) wet weight of specimens from the vents with respect to animals living in high pH/low pCO2 areas. Moreover, individuals living in the Castello vents showed doubled values of enzymatic activity and a significantly higher (50%) protein tissue content compared to specimens native from normal pH/low pCO2. The results of this study demonstrated that B. boholense is inclined to maintain a great homeostatic capacity when exposed to low pH, although likely at the energetic expense of other physiological processes such as growth, especially under chronic exposure to high pCO2.
Antioxidant efficiency of Platynereis spp. (Annelida, Nereididae) under different pH conditions at a vent’s system
Published 28 January 2019 Science ClosedTags: annelids, biological response, field, Mediterranean, physiology, vents
Marine organisms are exposed to a pH decrease and to alteration of carbonate chemistry due to ocean acidification (OA) that can represent a source of oxidative stress which can significantly affect their antioxidant defence systems efficiency. The polychaetes Platynereis dumerilii and P. massiliensis (Nereididae) are key species of the benthic community to investigate the effect of OA due to their physiological and ecological characteristics that enable them to persist even in naturally acidified CO2 vent systems. Previous studies have documented the ability of these species to adapt to OA after short- and long-term translocation experiments, but no one has ever evaluated the basal antioxidant system efficiency comparing populations permanently living in habitat characterized by different pH conditions (acidified vs. control). Here, individuals of both Platynereis species, sampled from a natural CO2 vent system and from a nonventing “control” site in three different periods (April 2016, October 2016, and February 2017), were compared highlighting signals which suggested the ability of both species to acclimatize to high pCO2–low pH with slight seasonal variations of their antioxidant efficiency and the absence of disturbances of the oxidative status of Platynereis spp. tissues.
The weakest link: sensitivity to climate extremes across life stages of marine invertebrates
Published 17 December 2018 Science ClosedTags: annelids, arthropoda, biological response, chordata, cnidaria, echinoderms, mollusks, mortality, review
Predicting the effects of climate change on Earth’s biota becomes even more challenging when acknowledging that most species have life cycles consisting of multiple stages, each of which may respond differently to extreme environmental conditions. There is currently no clear consensus regarding which stages are most susceptible to increasing environmental stress, or ‘climate extremes’. We used a meta‐analytic approach to quantify variation in responses to environmental stress across multiple life stages of marine invertebrates. We identified 287 experiments in 29 papers which examined the lethal thresholds of multiple life stages (embryo, larva, juvenile, and adult) of both holoplanktonic and meroplanktonic marine invertebrates subjected to the same experimental conditions of warming, acidification, and hypoxia stress. Most studies considered short acute exposure to stressors. We calculated effect sizes (log response ratio) for each life stage (unpaired analysis) and the difference in effect sizes between stages of each species (paired analysis) included in each experiment. In the unpaired analysis, all significant responses were negative, indicating that warming, acidification and hypoxia tended to increase mortality. Furthermore, embryos, larvae, and juveniles were more negatively affected by warming than adults. The paired analysis revealed that, when subjected to the same experimental conditions, younger life stages were more negatively affected by warming than older life stages, specifically among pairings of adults vs. juveniles and larvae vs. embryos. Although responses to warming are well documented, few studies of the effects of acidification and hypoxia met the criteria for inclusion in our analyses. Our results suggest that while most life stages will be negatively affected by climate change, younger stages of marine invertebrates are more sensitive to extreme heating events.
Rapid bioerosion in a tropical upwelling coral reef
Published 21 September 2018 Science ClosedTags: annelids, biogeochemistry, biological response, chemistry, corals, crustaceans, field, mollusks, North Pacific
Coral reefs persist in an accretion-erosion balance, which is critical for understanding the natural variability of sediment production, reef accretion, and their effects on the carbonate budget. Bioerosion (i.e. biodegradation of substrate) and encrustation (i.e. calcified overgrowth on substrate) influence the carbonate budget and the ecological functions of coral reefs, by substrate formation/consolidation/erosion, food availability and nutrient cycling. This study investigates settlement succession and carbonate budget change by bioeroding and encrusting calcifying organisms on experimentally deployed coral substrates (skeletal fragments of Stylophora pistillata branches). The substrates were deployed in a marginal coral reef located in the Gulf of Papagayo (Costa Rica, Eastern Tropical Pacific) for four months during the northern winter upwelling period (December 2013 to March 2014), and consecutively sampled after each month. Due to the upwelling environmental conditions within the Eastern Tropical Pacific, this region serves as a natural laboratory to study ecological processes such as bioerosion, which may reflect climate change scenarios. Time-series analyses showed a rapid settlement of bioeroders, particularly of lithophagine bivalves of the genus Lithophaga/Leiosolenus (Dillwyn, 1817), within the first two months of exposure. The observed enhanced calcium carbonate loss of coral substrate (>30%) may influence seawater carbon chemistry. This is evident by measurements of an elevated seawater pH (>8.2) and aragonite saturation state (Ωarag >3) at Matapalo Reef during the upwelling period, when compared to a previous upwelling event observed at a nearby site in distance to a coral reef (Marina Papagayo). Due to the resulting local carbonate buffer effect of the seawater, an influx of atmospheric CO2 into reef waters was observed. Substrates showed no secondary cements in thin-section analyses, despite constant seawater carbonate oversaturation (Ωarag >2.8) during the field experiment. Micro Computerized Tomography (μCT) scans and microcast-embeddings of the substrates revealed that the carbonate loss was primarily due to internal macrobioerosion and an increase in microbioerosion. This study emphasizes the interconnected effects of upwelling and carbonate bioerosion on the reef carbonate budget and the ecological turnovers of carbonate producers in tropical coral reefs under environmental change.
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Ocean acidification drives community shifts towards simplified non-calcified habitats in a subtropical−temperate transition zone
Published 27 July 2018 Science ClosedTags: algae, annelids, biological response, BRcommunity, chemistry, community composition, corals, crustaceans, field, mollusks, North Pacific, otherprocess, vents
Rising atmospheric concentrations of carbon dioxide are causing surface seawater pH and carbonate ion concentrations to fall in a process known as ocean acidification. To assess the likely ecological effects of ocean acidification we compared intertidal and subtidal marine communities at increasing levels of pCO2 at recently discovered volcanic seeps off the Pacific coast of Japan (34° N). This study region is of particular interest for ocean acidification research as it has naturally low levels of surface seawater pCO2 (280–320 µatm) and is located at a transition zone between temperate and sub-tropical communities. We provide the first assessment of ocean acidification effects at a biogeographic boundary. Marine communities exposed to mean levels of pCO2 predicted by 2050 experienced periods of low aragonite saturation and high dissolved inorganic carbon. These two factors combined to cause marked community shifts and a major decline in biodiversity, including the loss of key habitat-forming species, with even more extreme community changes expected by 2100. Our results provide empirical evidence that near-future levels of pCO2 shift sub-tropical ecosystems from carbonate to fleshy algal dominated systems, accompanied by biodiversity loss and major simplification of the ecosystem.
