Isotope ratios, trace elements and ultrastructure results of Mytilus galloprovincialis shells and experimental site data off Ischia (Italy)

Bivalve shells can provide excellent archives of past environmental change but have not been used to interpret ocean acidification events. We investigated carbon, oxygen and trace element records from different shell layers in the mussels Mytilus galloprovincialis combined with detailed investigations of the shell ultrastructure. Mussels from the harbour of Ischia (Mediterranean, Italy) were transplanted and grown in water with mean pHT 7.3 and mean pHT 8.1 near CO2 vents on the east coast of the island. Most prominently, the shells recorded the shock of transplantation, both in their shell ultrastructure, textural and geochemical record. Shell calcite, precipitated subsequently under acidified seawater responded to the pH gradient by an in part disturbed ultrastructure. Geochemical data from all test sites show a strong metabolic effect that exceeds the influence of the low-pH environment. These field experiments showed that care is needed when interpreting potential ocean acidification signals because various parameters affect shell chemistry and ultrastructure. Besides metabolic processes, seawater pH, factors such as salinity, water temperature, food availability and population density all affect the biogenic carbonate shell archive.

Experimental evaluation of seaweeds as a vector for microplastics into marine food webs, supplementary material

The ingestion of microplastics has been shown for a great variety of marine organisms. However, benthic marine mesoherbivores such as the common periwinkle Littorina littorea have been largely disregarded in studies about the effects of microplastics on the marine biota, probably because the pathway for microplastics to this functional group of organisms was not obvious. In laboratory experiments we showed that the seaweed Fucus vesiculosus retains suspended microplastics on its surface. The numbers of microplastics that adhered to the algae correlated with the concentrations of suspended particles in the water. In choice feeding assays L. littorea did not distinguish between algae with adherent microplastics and clean algae without microplastics, indicating that the snails do not recognize solid nonfood particles in the submillimeter size range as deleterious. In periwinkles that were feeding on contaminated algae, microplastics were found in the stomach and in the gut. However, no microplastics were found in the midgut gland, which is the principle digestive organ of gastropods. Microplastics in the fecal pellets of the periwinkles indicate that the particles do not accumulate rapidly inside the animals but are mostly released with the feces. Our results provide the first evidence that seaweeds may represent an efficient pathway for microplastics from the water to marine benthic herbivores.

Neogene planktonic foraminifera of DSDP Leg 41 holes

During Leg 41 Neogene sediments were recovered from five sites off northwest Africa. On the Sierra Leone Rise (Site 366), Neogene sediments consist of nanno oozes, nanno chalk, and calcareous clays 230 meters thick, resting conformably on the late Oligocene sediments. The common succession of zones occurs with two hiatuses. The lower gap corresponds to an interval around the lower/middle Miocene boundary (the Praeorbulina glomerosa and Orbulina suturalis-Globorotalia peri-pheroronda zones are absent) and the upper gap coincides with an interval around the middle/upper Miocene boundary (the Sphaeroidinellopsis sub-dehiscens-GIobigerina druryi, Globigerina nepenthes-Globorotalia siakensis and Globorotalia conlinuosa zones are missing). In the Cape Verde Basin (Site 367) deep-water Neogene turbidites (about 200-250 m thick) contain poor fauna of redeposited and sorted Cretaceous, Eocene, Oligocene, and Neogene species. On the Cape Verde Rise (Site 368) the Neogene section starts with slightly calcareous and non-calcareous clays with poor planktonic foraminifers of the lower Miocene. Later on this area was uplifted and clayey sediments have been replaced upsection in order by more shallow-water clayey nanno and nanno-foraminifer oozes and marls and pure calcareous oozes. In the middle Miocene, planktonic foraminifers are still not diverse, but since the level of the Globigerina nepenthes-Globorotalia siakensis Zone, almost all Neogene zones have been traced. The minimum thickness of the Neogene sediments is about 230 meters. On the continental slope off Spanish Sahara (Site 369) monotonous calcareous pelagic sediments of Neogene age (164 m thick) overlie the late Oligocene comformably, or with a small time gap. A set of zones beginning from the Globigerinoides primordis-Globorotaiia kugleri Zone up to the Globorotalia fohsi fohsi Zone has been revealed with a gap corresponding to the Globigerinita stainforthi and the Globigerinatella insueta-Globigerinoides irilobus zones. Above that follow sediments with heterogeneous microfauna which result from redeposition or mixing of sediments during drilling. The section ends with sediments of the late Miocene and lower Pliocene with abundant planktonic foraminifers. The latter are unconformably overlain by the Quaternary ooze. In the Morocco basin (Site 370) deep-water marls and calcareous clays of the lower Miocene contain poor assemblages of planktonic foraminifers. The middle and upper Miocene are represented by turbidites (alternation of nanno oozes, clays, siltstones, and sands) with heterogeneous microfauna. Total thickness of Neogene is up to 200 meters. In general the Neogene foraminifer microfauna of the area studied includes the majority of species which developed within the tropical-subtropical belt. The entire succession of the Miocene and Pliocene foraminifer zones occurs. The only exclusion is the Sphaeroidinellopsis subdehiscens-Globigerina druryi Zone of the middle Miocene. The distribution of species is shown on three tables. Comments are given for 47 species and subspecies of foraminifers (stratigraphic ranges, peculiarities of morphology, and ultrastructure of the shell wall).

Stomach content and parasite characteristics of M. scorpius from Frobisher Bay, Baffin Island

Shorthorn sculpin (Myoxocephalus scorpius) from Frobisher Bay, Baffin Island, is a slow growing long-lived species. A wide range of diet items were present in the stomachs of the shorthorn sculpins sampled but 2-3 diet items (amphipod species) comprised 99.5 % of total food consumed. These amphipods were present in the stomachs in similar proportions among all age classes of shorthorn sculpin. Several new host records for parasites were reported and mean numbers of parasite species increased with shorthorn sculpin age. The increased diversity of parasite species and higher d15N values in older/larger individuals suggest that their diets were more diverse and the prey items consumed had higher d15N values. By contrast, the value of d13C in dominant diet items masked the d13C values of minor diet items. We conclude that parasites and stable isotope values provide complementary data on feeding patterns of the shorthorn sculpin. The ubiquitous marine acanthocephalan, Echinorhynchus gadi, was found at high prevalences (87-100 %) and mean intensities (28-35), and were localized in the midgut. In contrast to other studies on acanthocephalans, E. gadi did not influence fish condition as measured by condition factor, liver somatic and gonado-somatic indices.

CO2-driven ocean acidification alters and weakens integrity of the calcareous tubes produced by the serpulid tubeworm, Hydroides elegans

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 (Omega A) 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 Omega A 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.

Temperature Dependent Effects of Elevated CO2 on Shell Composition and Mechanical Properties of Hydroides elegans: Insights from a Multiple Stressor Experiment

The majority of marine benthic invertebrates protect themselves from predators by producing calcareous tubes or shells that have remarkable mechanical strength. An elevation of CO2 or a decrease in pH in the environment can reduce intracellular pH at the site of calcification and thus interfere with animal's ability to accrete CaCO3. In nature, decreased pH in combination with stressors associated with climate change may result in the animal producing severely damaged and mechanically weak tubes. This study investigated how the interaction of environmental drivers affects production of calcareous tubes by the serpulid tubeworm, Hydroides elegans. In a factorial manipulative experiment, we analyzed the effects of pH (8.1 and 7.8), salinity (34 and 27), and temperature (23°C and 29°C) on the biomineral composition, ultrastructure and mechanical properties of the tubes. At an elevated temperature of 29°C, the tube calcite/aragonite ratio and Mg/Ca ratio were both increased, the Sr/Ca ratio was decreased, and the amorphous CaCO3 content was reduced. Notably, at elevated temperature with decreased pH and reduced salinity, the constructed tubes had a more compact ultrastructure with enhanced hardness and elasticity compared to decreased pH at ambient temperature. Thus, elevated temperature rescued the decreased pH-induced tube impairments. This indicates that tubeworms are likely to thrive in early subtropical summer climate. In the context of climate change, tubeworms could be resilient to the projected near-future decreased pH or salinity as long as surface seawater temperature rise at least by 4°C.

Seawater carbonate chemistry and biological processes of oysters Crassostrea virginica during experiments, 2010

Estuarine organisms are exposed to periodic strong fluctuations in seawater pH driven by biological carbon dioxide (CO2) production, which may in the future be further exacerbated by the ocean acidification associated with the global rise in CO2. Calcium carbonate-producing marine species such as mollusks are expected to be vulnerable to acidification of estuarine waters, since elevated CO2 concentration and lower pH lead to a decrease in the degree of saturation of water with respect to calcium carbonate, potentially affecting biomineralization. Our study demonstrates that the increase in CO2 partial pressure (pCO2) in seawater and associated decrease in pH within the environmentally relevant range for estuaries have negative effects on physiology, rates of shell deposition and mechanical properties of the shells of eastern oysters Crassostrea virginica (Gmelin). High CO2 levels (pH ~7.5, pCO2 ~3500 µatm) caused significant increases in juvenile mortality rates and inhibited both shell and soft-body growth compared to the control conditions (pH ~8.2, pCO2 ~380 µatm). Furthermore, elevated CO2 concentrations resulted in higher standard metabolic rates in oyster juveniles, likely due to the higher energy cost of homeostasis. The high CO2 conditions also led to changes in the ultrastructure and mechanical properties of shells, including increased thickness of the calcite laths within the hypostracum and reduced hardness and fracture toughness of the shells, indicating that elevated CO2 levels have negative effects on the biomineralization process. These data strongly suggest that the rise in CO2 can impact physiology and biomineralization in marine calcifiers such as eastern oysters, threatening their survival and potentially leading to profound ecological and economic impacts in estuarine ecosystems.

Ocean acidification reduces the crystallographic control in juvenile mussel shells

Global climate change threatens the oceans as anthropogenic carbon dioxide causes ocean acidification and reduced carbonate saturation. Future projections indicate under saturation of aragonite, and potentially calcite, in the oceans by 2100. Calcifying organisms are those most at risk from such ocean acidification, as carbonate is vital in the biomineralisation of their calcium carbonate protective shells. This study highlights the importance of multi-generational studies to investigate how marine organisms can potentially adapt to future projected global climate change. Mytilus edulis is an economically important marine calcifier vulnerable to decreasing carbonate saturation as their shells comprise two calcium carbonate polymorphs: aragonite and calcite. M. edulis specimens were cultured under current and projected pCO2 (380, 550, 750 and 1000 µatm), following 6 months of experimental culture, adults produced second generation juvenile mussels. Juvenile mussel shells were examined for structural and crystallographic orientation of aragonite and calcite. At 1000 µatm pCO2, juvenile mussels spawned and grown under this high pCO2 do not produce aragonite which is more vulnerable to carbonate under-saturation than calcite. Calcite and aragonite were produced at 380, 550 and 750 µatm pCO2. Electron back scatter diffraction analyses reveal less constraint in crystallographic orientation with increased pCO2. Shell formation is maintained, although the nacre crystals appear corroded and crystals are not so closely layered together. The differences in ultrastructure and crystallography in shells formed by juveniles spawned from adults in high pCO2 conditions may prove instrumental in their ability to survive ocean acidification.

(Table 1) Strontium isotope data for marine barnacles, ODP Hole 178-1103A

Strontium isotope ratios from multiple plates of two barnacle fragments from Site 1103 (Ocean Drilling Program Leg 178) provide maximum age estimates for the oldest glacial sedimentary package drilled. Three moderately preserved barnacle fragments from 262.63 meters below seafloor (mbsf) yielded a mean best-fit age of 7.4 Ma. A single, well-preserved fragment from the same horizon yielded a best-fit age of 12.2 Ma. Two moderately preserved fragments from 262.98 mbsf yielded a mean best-fit age of 7.8 Ma. The calculated mean strontium ages of 7.8 and 7.4 Ma agree well with the diatom estimates of 8.68 to 5.89 Ma for the underlying sediments.