Posts Tagged 'abundance'

Strong variation in sedimental antibiotic resistomes among urban rivers, estuaries and coastal oceans: evidence from a river-connected coastal water ecosystem in northern China

Sediment is thought to be a vital reservoir to spread antibiotic resistance genes (ARGs) among various natural environments. However, the spatial distribution patterns of the sedimental antibiotic resistomes around the Bohai Bay region, a river-connected coastal water ecosystem, are still poorly understood. The present study conducted a comprehensive investigation of ARGs among urban rivers (UR), estuaries (ES) and Bohai Bay (BHB) by metagenomic sequencing. Overall, a total of 169 unique ARGs conferring resistance to 15 antimicrobial classes were detected across all sediment samples. The Kruskal-Wallis test showed that the diversity and abundance of ARGs in the UR were all significantly higher than those in the ES and BHB (p < 0.05 and p < 0.01), revealing the distance dilution of the sedimental resistomes from the river to the ocean. Multidrug resistance genes contained most of the ARG subtypes, whereas rifamycin resistance genes were the most abundant ARGs in this region. Our study demonstrated that most antimicrobial resistomes were highly accumulated in urban river sediments, whereas beta-lactamase resistance genes (mainly PNGM-1) dramatically increased away from the estuary to the open ocean. The relative abundance of mobile genetic elements (MGEs) also gradually decreased from rivers to the coastal ocean, whereas the difference in pathogenic bacteria was not significant in the three classifications. Among MGEs, plasmids were recognized as the most important carriers to support the horizontal gene transfer of ARGs within and between species. According to co-occurrence networks, pathogenic Proteobacteria, Actinobacteria, and Bacteroidetes were recognized as potential and important hosts of ARGs. Heavy metals, pH and moisture content were all recognized as the vital environmental factors influencing the distribution of ARGs in sediment samples. Overall, the present study may help to understand the distribution patterns of ARGs at a watershed scale, and help to make effective policies to control the emergence, spread and evolution of different ARG subtypes in different habitats.

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Explosive volcanism periodicity past cycles record within the last 0.8 Mya evidenced by tephra and benthic foraminifera of IODP Hole U1485AA (Exp. 363 WPWP)

Volcanic eruptions with increase in the amount of carbon dioxide (CO2) and other gases are responsible for the extinction of many species because of decreased pH and carbonate availability which creates ocean acidification. Here we show how benthic foraminifera have evolved, by studying sediments from U1485A (1145 m water depth) core in the Papua New Guinea (PNG) collected during IODP Expedition 363 in the Western Pacific Warm Pool (WPWP), one of the warmest marine waters of the world. High-stressed environments dominated by low diversity of opportunistic species after volcanic activity was detected by the presence of tephra and volcanic ashes within the last 0.8 Mya. The decrease in the diversity patterns show an inverse correlation to the presence of tephra and ash right after Pleistocene volcanic eruptions in the past. Deep-water fauna is dominated by Cibicidoides pachiderma, from the early Oligocene through the Pleistocene, Uvigerina hispida from early Miocene through Pleistocene, U. prosbocidae from late Oligocene through Pleistocene, and an outer neritic upper bathyal Uvigerina mediterranea from high salinities, warm waters, low dissolved oxygen, and high organic matter. Bolivinita quadrilatera characteristic of 200-500m depth, Bolivina robusta from 3 to 900m, and the Rotalinoides compressiusculus, a shallow warm water species, from 2-37m depth show higher diversity peaks in interglacial cycles. High-stress conditions with mass extinction after volcanic eruptions leads to enhanced weathering, global warming and cooling afterwards, and ocean acidification, resulting in a crisis in the marine environment in terms of carbonate. Diversity gradients suggested that foraminiferal species responded to the cyclic pulses of volcanic eruptions, and its unstable ecological conditions created by the increase in the temperature and CO2. Here we show that tephra layers and ash record a periodicity of explosive volcanism within the last 0.8 Myr maintaining a strong 100 kyr periodicity, and that earth’s orbital cycles might trigger peaks of volcanic eruptions 41,000-year cycle.

Continue reading ‘Explosive volcanism periodicity past cycles record within the last 0.8 Mya evidenced by tephra and benthic foraminifera of IODP Hole U1485AA (Exp. 363 WPWP)’

Marine macroinvertebrate ecosystem services under changing conditions of seagrasses and mangroves


  • Overfishing and climate change show potential effects on MMI ES.
  • MMI regulating ES can be quantified using species richness and functional traits.
  • Digital platforms are valuable tools to retrieve data but have limitations.
  • Baseline data and information on environmental changes and MMI ES is provided.


This study aimed to investigate the impact of changing environmental conditions on MMI ES in seagrasses and mangroves. We used data from satellite and biodiversity platforms combined with field data to explore the links between ecosystem pressures (habitat conversion, overexploitation, climate change), conditions (environmental quality, ecosystem attributes), and MMI ES (provisioning, regulation, cultural). Both seagrass and mangrove extents increased significantly since 2016. While sea surface temperature showed no significant annual variation, sea surface partial pressure CO2, height above sea level and pH presented significant changes. Among the environmental quality variables only silicate, PO4 and phytoplankton showed significant annual varying trends. The MMI food provisioning increased significantly, indicating overexploitation that needs urgent attention. MMI regulation and cultural ES did not show significant trends overtime. Our results show that MMI ES are affected by multiple factors and their interactions can be complex and non-linear. We identified key research gaps and suggested future directions for research. We also provided relevant data that can support future ES assessments.

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Separate and combined effects of elevated pCO2 and temperature on the branching reef corals Acropora digitifera and Montipora digitata

Ocean acidification (OA) and warming (OW) are major global threats to coral reef ecosystems; however, studies on their combined effects (OA + OW) are scarce. Therefore, we evaluated the effects of OA, OW, and OA + OW in the branching reef corals Acropora digitifera and Montipora digitata, which have been found to respond differently to environmental changes. Our results indicate that OW has a greater impact on A. digitifera and M. digitata than OA and that the former species is more vulnerable to OW than the latter. OW was the main stressor for increased mortality and decreased calcification in the OA + OW group, and the effect of OA + OW was additive in both species. Our findings suggest that the relative abundance and cover of M. digitata are expected to increase whereas those of A. digitifera may decrease in the near future in Okinawa.

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Foraminiferal assemblages and test characteristics associated with natural low pH waters at Puerto Morelos reef lagoon springs, QR Mexico

Ocean acidification is expected to negatively affect many ecologically important organisms. Here we explored the response of Caribbean benthic foraminiferal assemblages to naturally discharging low-pH waters similar to expected future projections for the end of the 21st century. At low pH (~7.7 pH units) and low calcite saturation, agglutinated and symbiont-bearing species were relatively more abundant, indicating higher resistance to potential carbonate chemistry changes. Diversity and other taxonomical metrics declined steeply with decreasing pH, despite exposure of this ecosystem for millennia to low pH conditions, suggesting that tropical foraminifera communities will be negatively impacted under acidification scenarios SSP3-7.0 and SSP5-8.5. The species Archaias angulatus, a major contributor to sediment production in the Caribbean, was able to calcify at conditions more extreme than those projected for the late 21st century (7.1 pH units), but the calcified tests were of lower density than those exposed to higher-pH ambient conditions (7.96 pH units), indicating that reef foraminiferal carbonate budget might decrease. Smaller foraminifera were highly sensitive to decreasing pH and our results demonstrate their potential as indicators to monitor increasing OA conditions.

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Contrasting life cycles of Southern Ocean pteropods alter their vulnerability to climate change

Pteropods are a key part of biogeochemical cycling and epipelagic food webs in the Southern Ocean. However, shelled pteropods are vulnerable to climate change, due to their aragonite shells being particularly sensitive to ocean acidification. Currently our understanding of pteropod responses to environmental change is hindered by uncertainties surrounding their life cycles and population dynamics. In this study, we describe polar shelled pteropod diversity in the north-eastern Scotia Sea, inferring life history and population structures of the dominant pteropod species, Limacina rangii (formerly Limacina helicina antarctica) and Limacina retroversa. An annual timeseries of Limacina shell morphometrics was derived from individuals collected in a moored sediment trap at 400 m depth. We found that L. rangii and L. retroversa have contrasting life history strategies. L. rangii has a continuous spawning and recruitment period from November to March and can overwinter as juveniles and adults. L. retroversa has discrete spawning events from November to May, producing non–overlapping cohorts of juveniles and adults. Their development to the adult stage takes between two and five months, upon which they overwinter as adults. Our findings suggest different vulnerabilities of L. rangii and L. retroversa to a changing ocean. For example, since all life stages of L. rangii co-exist, vulnerability of one cohort is not detrimental to the stability of the overall population whereas, if one L. retroversa cohort fails to recruit, the entire population is threatened. Changes in pteropod populations could have cascading ramifications to Antarctic ecosystems and carbon cycling.

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Responses of biogenic dimethylated sulfur compounds to environmental changes in the northwestern Pacific continental sea

Continental seas are facing rapid environmental shifts, but how biogenic dimethylated sulfur compounds, including dimethylsulfide (DMS), dimethylsulfoniopropionate (DMSP), and dimethylsulfoxide (DMSO), will respond to these environmental changes remains poorly understood. Here we investigated the effects of nutrient input, ocean acidification, and dust deposition on the phytoplankton community and organic sulfur cycle in the East China Sea. Nutrient input promoted phytoplankton growth and increased the concentrations of DMS, DMSP, and DMSO. With sufficient nutrients, especially nitrate, the dissolved DMSP degradation was inhibited, and the bacterial DMSP-cleavage pathway (inferred by dddP gene abundance) was enhanced, causing increased DMS production. The sensitivity of phytoplankton biomass and DMS to ocean acidification varied with different initial nutrient levels, demonstrating insensitivity under eutrophic conditions and negative responses under nutrient-limited conditions. The ocean acidification promoted the dissolved DMSP degradation and bacterial DMSP-demethylation pathway (inferred by dmdA gene abundance) and weakened the DMS production, causing the decreases of DMS and DMSP. The nutrient from dust deposition (2 mg L−1) was identified as the key factor in enhancing phytoplankton biomass and the organic sulfur compounds concentrations, but trace metals input from dust deposition had no significant effect. This study has identified environmental drivers and suppressors of phytoplankton and biogenic dimethylated sulfur compounds in a changing marine environment, which will enable the effective modeling of future climate change.

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Effects of elevated temperature and acidification on sulfate assimilation and reduction of microalgae

Increased temperature and acidification are two important environmental factors affecting algal growth in marine ecosystems with the increase of atmospheric CO2. The dinoflagellate Amphidinium carterae and the diatom Phaeodactylum tricornutum were chosen to study the effect of warming and acidification on their sulfate assimilation and reduction processes by continuous incubation at different temperatures (15, 20 and 25 °C) and pHNBS values (8.10, 7.80 and 7.60). Variations in associated sulfur compounds, namely sulfate, dimethylsulfoniopropionate (DMSP), dimethylsulfide (DMS) and acrylic acid (AA) were observed. The largest sulfate uptake was at 25 °C for A. carterae and at 20 °C for P. tricornutum, however, the optimal growth temperature for both microalgae was 20 °C. The release of DMSP and DMS decreased in A. carterae while they increased in P. tricornutum under the condition of increased temperature. Seawater acidification increased the uptake of sulfate and promoted the growth of the microalgae. Acidification also reduced the release of DMSP, dissolved DMSP (DMSPd), DMS and AA from A. carterae with mean values of 55%, 22%, 9% and 40%, respectively. However, acidification increased the release of DMSP and DMSPd by P. tricornutum with mean values of 44% and 186%, the release of DMS was inhibited (25%) and with no significant difference in the release of AA (2%). Amino acids were found to inhibit the uptake of sulfate by the two microalgae, and the inhibitory effect of cysteine was found to be stronger than that of methionine. The inhibitory effect of amino acids was temperature sensitive and relatively weak at 20 °C. Besides, acidification could enhance the inhibitory effect and was evident in A. carterae. The sulfur metabolism intermediates (cysteine and methionine) have a feedback regulation effect on the sulfate absorption process of algae.

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Ocean warming and CO2-driven acidification can alter the toxicity of metal-contaminated sediments to the meiofauna community


  • Contamination interacted with warming but the effect on density was taxon dependent.
  • Warming increased metal effects in nematods and copepods, and decreased in acoelomorphs.
  • Copepod densities were lower, and acoelomorphs higher, in the high CO2/low pH scenario.
  • Global change studies should consider multispecies exposures in multi-stressor scenarios.


Interactive effects of trace metal contamination, ocean warming, and CO2-driven acidification on the structure of a meiofaunal benthic community was assessed. Meiofauna microcosm bioassays were carried out in controlled conditions in a full factorial experimental design which included three fixed factors: metal contamination in the sediment (3 levels of a mixture of Cu, Pb, Zn, and Hg), temperature (26 and 28 °C) and pH (7.6 and 8.1). Metal contamination caused a sharp decrease in the densities of the most abundant meiobenthic groups and interacted with temperature rise, exacerbating deleterious effects for Nematoda and Copepoda, but mitigating effects for Acoelomorpha. CO2-driven acidification resulted in increased acoelomorphs density, but only in sediments with lower levels of metals. Copepod densities, in turn, were lower in the CO2-driven acidification scenario regardless of contamination or temperature. The results obtained in the present study showed that temperature rise and CO2-driven acidification of coastal ocean waters, at environmentally relevant levels, interacts with trace metals in marine sediments, differently affecting the major groups of benthic biota.

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Coral persistence despite marginal conditions in the Port of Miami

Coral cover has declined worldwide due to anthropogenic stressors that manifest on both global and local scales. Coral communities that exist in extreme conditions can provide information on how these stressors influence ecosystem structure, with implications for their persistence under future conditions. The Port of Miami is located within an urbanized environment, with active coastal development, as well as commercial shipping and recreational boating activity. Monitoring of sites throughout the Port since 2018 has revealed periodic extremes in temperature, seawater pH, and salinity, far in excess of what have been measured in most coral reef environments. Despite conditions that would kill many reef species, we have documented diverse coral communities growing on artificial substrates at these sites—reflecting remarkable tolerance to environmental stressors. Furthermore, many of the more prevalent species within these communities are now conspicuously absent or in low abundance on nearby reefs, owing to their susceptibility and exposure to stony coral tissue loss disease. Natural reef frameworks, however, are largely absent at the urban sites and while diverse fish communities are documented, it is unlikely that these communities provide the same goods and services as natural reef habitats. Regardless, the existence of these communities indicates unlikely persistence and highlights the potential for coexistence of threatened species in anthropogenic environments, provided that suitable stewardship strategies are in place.

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Acidification scenario of Cox’s Bazar coast of the Bay of Bengal, Bangladesh and its influence on fish larvae abundance

Ocean acidification is caused mainly by atmospheric carbon dioxide stored in the ocean. Ocean acidification is considered a major threat to aquatic life, and how it influences the abundance of marine fish larvae is still unclear. This research was designed to measure the current ocean acidification scenario of the Cox’s Bazar coast of the Bay of Bengal, Bangladesh, and its probable influence on the abundance of fish larvae. Three research stations were selected: Bakkhali river estuary, Naf river estuary, and Rezu Khal. Monthly sampling was done, and larvae sample was collected from the surface water column (depth: 0.5 m) using a bongo net. Water parameters such as temperature, salinity, total alkalinity, and pH were determined using laboratory protocol. The seacarb package of the R programming language was used to determine ocean acidification factors. The Bakkhali river estuary showed the highest partial carbon dioxide (143.99 ± 102.27 μatm) and the lowest pH (8.27 ± 0.21). A total of 19 larvae families were identified, and the highest larval count was found in Rezu Khal (390 larvae/1000 m3), while the lowest was found in the Bakkhali river (3 larvae/1000 m3). ClupeidaeMyctophidae, and Engraulidae comprised more than 50% of the identified larvae. BlenniidaeCarangidae, Clupeidae, Engraulidae, and Gobiidae were found in all three seasons. Most of the larvae families showed the highest mean abundance under less pCO2. A negative correlation was observed between larvae and acidification factors such as pCO2, HCO3, and dissolved inorganic carbon (DIC). The study revealed that acidification parameters of the Cox’s Bazar coast were not in an acute state for the aquatic organisms’ survival, but fish larvae abundance could be declined with raises in the partial carbon dioxide. The results of this study may aid in developing a management plan for conserving Bangladesh’s marine and coastal fish.

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Calcification response of planktic foraminifera to environmental change in the western Mediterranean Sea during the industrial era (update)

The Mediterranean Sea sustains a rich and fragile ecosystem currently threatened by multiple anthropogenic impacts that include, among others, warming, pollution, and changes in seawater carbonate speciation associated to increasing uptake of atmospheric CO2. This environmental change represents a major risk for marine calcifiers such as planktonic foraminifera, key components of pelagic Mediterranean ecosystems and major exporters of calcium carbonate to the sea floor, thereby playing a major role in the marine carbon cycle. In this study, we investigate the response of planktic foraminifera calcification in the northwestern Mediterranean Sea on different timescales across the industrial era. This study is based on data from a 12-year-long sediment trap record retrieved in the in the Gulf of Lions and seabed sediment samples from the Gulf of Lions and the promontory of Menorca. Three different planktic foraminifera species were selected based on their different ecology and abundance: Globigerina bulloidesNeogloboquadrina incompta, and Globorotalia truncatulinoides. A total of 273 samples were weighted in both sediment trap and seabed samples.

The results of our study suggest substantial different seasonal calcification patterns across species: G. bulloides shows a slight calcification increase during the high productivity period, while both N. incompta and G. truncatulinoides display a higher calcification during the low productivity period. The comparison of these patterns with environmental parameters indicate that controls on seasonal calcification are species-specific. Interannual analysis suggests that both G. bulloides and N. incompta did not significantly reduce their calcification between 1994 and 2005, while G. truncatulinoides exhibited a constant and pronounced increase in its calcification that translated in an increase of 20 % of its shell weight. The comparison of these patterns with environmental data reveals that optimum growth conditions affect positively and negatively G. bulloides and G. truncatulinoides calcification, respectively. Sea surface temperatures (SSTs) have a positive influence on N. incompta and G. truncatulinoides calcification, while carbonate system parameters appear to affect positively the calcification of three species in the Gulf of Lions throughout the 12-year time series.

Finally, comparison between sediment trap data and seabed sediments allowed us to assess the changes of planktic foraminifera calcification during the late Holocene, including the pre-industrial era. Several lines of evidence indicate that selective dissolution did not bias the results in any of our data sets. Our results showed a weight reduction between pre-industrial and post-industrial Holocene and recent data, with G. truncatulinoides experiencing the largest weight loss (32 %–40 %) followed by G. bulloides (18 %–24 %) and N. incompta (9 %–18 %). Overall, our results provide evidence of a decrease in planktic foraminifera calcification in the western Mediterranean, most likely associated with ongoing ocean acidification and regional SST trends, a feature consistent with previous observations in other settings of the world’s oceans.

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Biocalcification crisis in the continental shelf under ocean acidification


  • An eight months’ ocean acidification (OA) simulation experiment was conducted.
  • The ecological and biological responses of benthic foraminifera to OA was studied.
  • Benthic foraminifera in nearshore area had more resistance to OA than offshore one.
  • Thinner and smaller shells in calcareous foraminifera were produced under OA.
  • There will be a biocalcification crisis in continental shelf under future OA.


Ocean acidification (OA) is a persistent challenge for humans and is predicted to have deleterious effects on marine organisms, especially marine calcifiers such as coral and foraminifera. Benthic foraminifera is an important component of sediment in the continental shelf, while little is known about the impact of ocean acidification on benthic foraminifera both at the community and individual level and associated calcium carbonate deposition. We conducted eight months continued culture experiment under the scenario of 400, 800, 1200 and 1600 ppm pCO2 gradients on living benthic foraminifera from four stations in the continental shelf of the West Pacific Ocean. Statistic results showed OA had a negative effect on the abundance of benthic foraminifera. In contrast, the diversity increased roughly under OA conditions implying OA might stimulate the emergence of rare species and promote community diversity to some extent. In addition, we confirmed that the offshore area wasn’t the refuge for benthic foraminifera while the nearshore one had more resistance to moderate acidification. Calcareous species Protelphidium tuberculatum was the dominant species occupying on average 75% in all treatments and its shell diameter, weight and thickness showed a decrease, indicating the decrease of calcification of benthic foraminifera. A relationship between the weight of P. tuberculatum and pCO2 (R2 = 0.96) was established. Based on the present work, calcareous benthic foraminifera deposited 8.57×104 t calcium carbonate per year and this might reduce by nearly half and 90% under 800 and 1200 ppm scenarios, which indicates a biocalcification crisis under ongoing OA. This work shows an analogy for palaeoceanic OA and also provides new insights into the sediment of calcium carbonate in the future.

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Assessing the impacts of simulated ocean alkalinity enhancement on viability and growth of cultures of near-shore species of phytoplankton

Over the past 250 years, atmospheric carbon dioxide concentrations have risen steadily from 277 ppm to 405 ppm, leading to the exacerbation of the effects of climate change. As a result, new technologies are being developed to remove carbon from the atmosphere, such as negative emission technologies (NETs). One proposed NET is Ocean Alkalinity Enhancement (OAE), which would mimic the ocean’s natural weathering processes and sequester carbon dioxide from the atmosphere. An analysis of published data investigating the effects of elevated pH on phytoplankton growth rate and experimental assessment of pH dependence of viability and growth rate was used to assess the potential impacts of OAE. Viability was assessed with a modified Serial Dilution Culture – Most Probable Number assay. Chlorophyll a fluorescence was used to test for changes in growth rates and photosynthetic competence. The results from this study suggest that there will be no significant impact on the viability or growth rates of Thalassiosira pseudonana or Pavlova lutheri with short-term (10 minute) exposure to elevated pH. However, when long-term (days) exposure occurs there is a significant decrease in growth rates with elevated pH. Short-term exposure is anticipated to more closely mirror the natural systems in which OAE will be implemented because of system flushing and replenishment of nutrients. These preliminary findings suggest that there will be little to no impact on a variety of taxonomic groups of phytoplankton when OAE occurs in naturally flushed systems.

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Addressing the joint impact of temperature and pH on Vibrio harveyi adaptation in the time of climate change

Global warming and acidification of the global ocean are two important manifestations of the ongoing climate change. To characterize their joint impact on Vibrio adaptation and fitness, we analyzed the temperature-dependent adaptation of Vibrio harveyi at different pHs (7.0, 7.5, 8.0, 8.3 and 8.5) that mimic the pH of the world ocean in the past, present and future. Comparison of V. harveyi growth at 20, 25 and 30 °C show that higher temperature per se facilitates the logarithmic growth of V. harveyi in nutrient-rich environments in a pH-dependent manner. Further survival tests carried out in artificial seawater for 35 days revealed that cell culturability declined significantly upon incubation at 25 °C and 30 °C but not at 20 °C. Moreover, although acidification displayed a negative impact on cell culturability at 25 °C, it appeared to play a minor role at 30 °C, suggesting that elevated temperature, rather than pH, was the key player in the observed reduction of cell culturability. In addition, analyses of the stressed cell morphology and size distribution by epifluorescent microscopy indicates that V. harveyi likely exploits different adaptation strategies (e.g., acquisition of coccoid-like morphology) whose roles might differ depending on the temperature–pH combination.

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Morpho-anatomical, and chemical characterization of some calcareous Mediterranean red algae species

Climatic changes are anticipated to have a detrimental effect on calcifying marine species. Calcareous red algae may be especially vulnerable to seasonal variations since they are common and essential biologically, but there is little research on the morpho-anatomical, and chemical characterization of such species. This study conducted the seasonal investigation of the three dominant Mediterranean calcified red algae. Morphological and 18S rRNA analysis confirmed the identification of collected species as Corallina officinalis, Jania rubens, and Amphiroa rigida. In general, C. officinalis was represented in the four seasons and flourishing maximum in autumn (70% of total species individuals). While J. rubens species was represented in winter, autumn, and spring and completely absent in summer. A. rigida was abundant only in the summer season by 40%. A full morphological and anatomical description of these species were examined, and their chemical compositions (carbohydrate, protein, lipid, pigments, and elements content) were assessed in different seasons, where carbohydrates were the dominant accumulates followed by proteins and lipids. Pearson correlation analysis confirmed a positive correlation between salinity level and nitrogenous nutrients of the seawater with the pigment contents (phycobiliproteins, carotenoids, and chlorophyll a) of the studied seaweeds. The results proved that calcified red algae were able to deposit a mixture of calcium carbonates such as calcite, vaterite, calcium oxalate, calcite-III I calcium carbonate, and aragonite in variable forms depending on the species.

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Ocean acidification has a strong effect on communities living on plastic in mesocosms

We conducted a mesocosm experiment to examine how ocean acidification (OA) affects communities of prokaryotes and eukaryotes growing on single-use drinking bottles in subtropical eutrophic waters of the East China Sea. Based on 16S rDNA gene sequencing, simulated high CO2 significantly altered the prokaryotic community, with the relative abundance of the phylum Planctomycetota increasing by 49%. Under high CO2, prokaryotes in the plastisphere had enhanced nitrogen dissimilation and ureolysis, raising the possibility that OA may modify nutrient cycling in subtropical eutrophic waters. The relative abundance of pathogenic and animal parasite bacteria also increased under simulated high CO2. Our results show that elevated CO2 levels significantly affected several animal taxa based on 18S rDNA gene sequencing. For example, Mayorella amoebae were highly resistant, whereas Labyrinthula were sensitive to OA. Thus, OA may alter plastisphere food chains in subtropical eutrophic waters.

Scientific Significance Statement

Plastic waste in the ocean is an urgent environmental concern and has given rise to a novel habitat, known as the “plastisphere.” Under ocean acidification (OA), changes in plastisphere community composition may alter plastic degradation, deposition, and passage through food webs, but these have not been studied yet. This is the first study about the effects of simulated high CO2 on the plastisphere using a mesocosm. We discovered that after 1 month the beta diversity of prokaryotic communities living on single-use plastic drinking bottles was significantly different under different carbon dioxide concentrations, with more pathogens at high CO2. Based on function prediction analysis, the relative abundance of bacterial taxa involved in nitrogen and nitrate respiration and ureolysis was significantly higher under simulated high CO2. We conclude that OA has significant effects on the plastisphere and its predicted functions.

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Benthic foraminiferal turnover and trait changes across the Palaeocene–Eocene Thermal Maximum (PETM) at ODP site 1265A, Walvis Ridge, SE Atlantic Ocean

Benthic foraminiferal turnover during the Palaeocene–Eocene Thermal Maximum (PETM) has been extensively studied but numerous questions remained unresolved, question such as why some foraminiferal species went into extinction at a particular location but survive in another or why some species survive in extremely low oxygen environment. Because foraminiferal community interaction with the environment is driven by biological traits instead of taxonomic composition, this study has adopted trait-based approach to provide insight into the life strategies of foraminifera that enables them to survive in extreme environmental conditions. The result from this study shows that traits such as test composition, perforation, ornamentation and living habits play an important role in the ecological functioning and adaptability of foraminifera in the environment. The faunal assemblage in the studied site is dominantly cosmopolitan taxa suggesting the environment was perturbed during the PETM. Foraminiferal composition is characterised by faunal turnover indicated in extensive mortalities and extinction of both planktonic and benthic fauna. The ordination (non-metric dimensional scaling) of faunal composition also indicated ecological disturbance. The planktonic community was relatively stable before and after PETM but experienced a high level of ecological perturbation during the carbon isotopic excursion (CIE). The benthic community showed higher evidence of perturbation as the fauna assemblage ordination indicated that ecological stress started before the PETM with the disarray of samples in the ordination diagram. Only the recovery interval experienced some level of ecological stability. The environmental disturbance noticed in the fauna composition reflected on the trait. Benthic foraminiferal traits indicated instability throughout the studied section. The evidence of environmental disturbance in the benthic community suggests that the source of the light carbon that caused the PETM may have originated beneath sea floor in the Atlantic Ocean.

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Abundance and size structure of Patella spp. (Mollusca, Gastropoda) under ocean acidification conditions at CO2 vents (Ischia Island, Italy)

Abundance and size structure of Patella spp. were studied at Ischia Island (Tyrrhenian Sea) in two populations living at CO2 vents off Castello Aragonese, under natural ocean acidification (OA) conditions (pH 7.4-7.9), and three control populations in sites characterized by normal pH conditions (pH 8.1). Both CO2 vent populations had 95% of heavily corroded shells and significant lower abundances than control populations, while the size structure showed individuals of higher dimensions (>2 cm), fewer small specimens (0-1 cm) and lack of new recruits in the vent’s populations subjected to OA conditions. These results confirm that, although with low densities, limpets thrive under OA conditions, and exhibit larger sizes, than in control areas, but a reduced recruitment of juveniles. This fact suggests a habitat selection only by adult specimens likely more robust to OA then juveniles, and the potential influence of other indirect factors, such as the amount and quality of the plant food (higher N content), which seems higher under OA conditions, or a reduced predation, that can explain the larger limpet’s size.

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High abundances of zooxanthellate zoantharians (Palythoa and Zoanthus) at multiple natural analogues: potential model anthozoans?

Whilst natural analogues for future ocean conditions such as CO2 seeps and enclosed lagoons in coral reef regions have received much recent research attention, most efforts in such locations have focused on the effects of prolonged high CO2 levels on scleractinian corals and fishes. Here, we demonstrate that the three species of zooxanthellate zoantharians, hexacorallian non-calcifying “cousins” of scleractinians, are common across five coral reef natural analogue sites with high CO2 levels in the western Pacific Ocean, in Japan (n = 2), Palau, Papua New Guinea, and New Caledonia (n = 1 each). These current observations support previously reported cases of high Palythoa and Zoanthus abundance and dominance on various impacted coral reefs worldwide. The results demonstrate the need for more research on the ecological roles of zooxanthellate zoantharians in coral reef systems, as well as examining other “understudied” taxa that may become increasingly important in the near future under climate change scenarios. Given their abundance in these sites combined with ease in sampling and non-CITES status, some zoantharian species should make excellent hexacoral models for examining potential resilience or resistance mechanisms of anthozoans to future high pCO2 conditions.

Continue reading ‘High abundances of zooxanthellate zoantharians (Palythoa and Zoanthus) at multiple natural analogues: potential model anthozoans?’

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