The impact of aragonite saturation variability on shelled pteropods: An attribution study in the California Current System.

Observations from the California Current System (CalCS) indicate that the long-term trend in ocean acidification (OA) and the naturally occurring corrosive conditions for the CaCO3 mineral aragonite (saturation state Ω < 1) have a damaging effect on shelled pteropods, a keystone group of calcifying organisms in the CalCS. Concern is heightened by recent findings suggesting that shell formation and developmental progress are already impacted when Ω falls below 1.5. Here, we quantify the impact of low Ω conditions on pteropods using an individual-based model (IBM) with life-stage-specific mortality, growth, and behavior in a high-resolution regional hindcast simulation of the CalCS between 1984 and 2019. Special attention is paid to attributing this impact to different processes that lead to such low Ω conditions, namely natural variability, long-term trend, and extreme events. We find that much of the observed damage in the CalCS, and specifically >70% of the shell CaCO3 loss, is due to the pteropods' exposure to naturally occurring low Ω conditions as a result of their diel vertical migration (DVM). Over the hindcast period, their exposure to damaging waters (Ω < 1.5) increases from 9% to 49%, doubling their shell CaCO3 loss, and increasing their mortality by ~40%. Most of this increased exposure is due to the shoaling of low Ω waters driven by the long-term trend in OA. Extreme OA events amplify this increase by ~40%. Our approach can quantify the health of pteropod populations under shifting environmental conditions, and attribute changes in fitness or population structure to changes in the stressor landscape across hierarchical time scales.

The modeling method for vibration characteristics analysis of composite laminated rotationally stiffened shell.

The composite laminated rotationally stiffened shell is widely applied in aviation, aerospace, ship, machinery and other fields. To investigate the vibration characteristics of composite laminated rotationally stiffened shells with varying elastic boundary conditions, a modeling method of composite laminated rotationally stiffened shells is established. Firstly, the first-order shear deformation theory (FSDT) and the modified Fourier series method are effectively applied to establish the allowable displacement function of the composite laminated rotationally stiffened shell. Secondly, the energy function of composite laminated rotationally stiffened shell is established, and the simulation of complex elastic boundary and coupling boundary is realized by using artificial virtual spring technology. Thirdly, the Rayleigh-Ritz method is used to solve the energy function. Finally, the vibration characteristics of composite laminated rotationally stiffened shells are obtained and analyzed. In the analysis of numerical results, the fast and uniform convergence of analysis modeling and the accuracy of the calculated results are verified. On this basis, the effect of some important parameters such as thickness-to-radius ratio and length-to-radius ratio of shell, boundary spring stiffness values, cone apex angle, thickness and width of laminated beams, number of stiffeners on the vibration characteristics of composite laminated rotationally stiffened shell is studied. In theory, it makes up for the vibration characteristics analysis of composite laminated rotationally stiffened shells. In practical application, it guides the noise reduction design of related structures.

Molluscs generate preferred crystallographic orientation of biominerals by organic templates, the texture and microstructure of Caudofoveata (Aplacophora) shells.

Caudofoveata are molluscs that protect their vermiform body with a scleritome, a mosaic of unconnected blade/lanceolate-shaped aragonite sclerites. For the species Falcidens gutturosus and Scutopus ventrolineatus we studied the crystallographic constitution and crystal orientation texture of the sclerites and the scleritome with electron-backscatter-diffraction (EBSD), laser-confocal-microscopy (LCM) and field-emission electron microscopy (FE-SEM) imaging. Each sclerite is an aragonite single crystal that is completely enveloped by an organic sheath. Adjacent sclerites overlap laterally and vertically are, however, not connected to each other. Sclerites are thickened in their central portion, relative to their periphery. Thickening increases also from sclerite tip towards its base. Accordingly, cross-sections through a sclerite are straight at its tip, curved and bent towards the sclerite base. Irrespective of curved sclerite morphologies, the aragonite lattice within the sclerite is coherent. Sclerite aragonite is not twinned. For each sclerite the crystallographic c-axis is parallel to the morphological long axis of the sclerite, the a-axis is perpendicular to its width and the b-axis is within the width of the sclerite. The single-crystalinity of the sclerites and their mode of organization in the scleritome is outstanding. Sclerite and aragonite arrangement in the scleritome is not given by a specific crystal growth mode, it is inherent to the secreting cells. We discuss that morphological characteristics of the sclerites and crystallographic preferred orientation (texture) of sclerite aragonite is not the result of competitive growth selection. It is generated by the templating effect of the organic substance of the secreting cells and associated extracellular biopolymers.

Activating Adsorption Sites of Waste Crayfish Shells via Chemical Decalcification for Efficient Capturing of Nanoplastics.

The property of being stubborn and degradation resistant makes nanoplastic (NP) pollution a long-standing remaining challenge. Here, we apply a designed top-down strategy to leverage the natural hierarchical structure of waste crayfish shells with exposed functional groups for efficient NP capture. The crayfish shell-based organic skeleton with improved flexibility, strength (14.37 to 60.13 MPa), and toughness (24.61 to 278.98 MJ m-3) was prepared by purposefully removing the inorganic components of crayfish shells through a simple two-step acid-alkali treatment. Due to the activated functional groups (e.g., -NH2, -CONH-, and -OH) and ordered architectures with macropores and nanofibers, this porous crayfish shell exhibited effective removal capability of NPs (72.92 mg g-1) by physical interception and hydrogen bond/electrostatic interactions. Moreover, the sustainability and stability of this porous crayfish shell were demonstrated by the maintained high-capture performance after five cycles. Finally, we provided a postprocessing approach that could convert both porous crayfish shell and NPs into a tough flat sheet. Thus, our feasible top-down engineering strategy combined with promising posttreatment is a powerful contender for a recycling approach with broad application scenarios and clear economic advantages for simultaneously addressing both waste biomass and NP pollutants.

The role of the carapace in the accumulation of metals from seawater in the green crab (Carcinus maenas): Studies with radio-labeled calcium, zinc, and nickel.

The role of the carapace in the uptake and storage of newly accumulated metals was investigated in the green crab exposed to environmentally relevant concentrations of calcium ([Ca] = 389 mg L-1 or 9.7 mmol L-1), zinc ([Zn] = 82 µg L-1 or 1.25 µmol L-1), and nickel ([Ni] = 8.2 µg L-1 or 0.14 µmol L-1) in 12 °C seawater, using radio-tracers (45Ca, 65Zn, 63Ni). After 24-h exposure, carapace exhibited the highest concentration of newly accumulated Ca, whereas carapace and gills exhibited the highest concentrations of both newly accumulated Zn and Ni relative to other tissues. For all three metals, the carapace accounted for >85 % of the total body burden. Acute temperature changes (to 2 °C and 22 °C) revealed the highest overall temperature coefficient Q10 (2.15) for Ca uptake into the carapace, intermediate Q10 for Ni (1.87) and lowest Q10 (1.45) for Zn. New Ca uptake into the carapace continued linearly with time for 24 h, new Zn uptake gradually deviated from linearity, whereas Ni uptake reached a plateau by 6 h. Attachment of a rubber membrane to the dorsal carapace, thereby shielding about 20 % of the total crab surface area from the external water, eliminated both new Zn and Ni incorporation into the shielded carapace, whereas 36 % of new Ca incorporation persisted. When recently euthanized crabs were exposed, new Zn uptake into the carapace remained unchanged, whereas Ca and Ni uptake were reduced by 89 % and 71 %, respectively. We conclude that the carapace is a very important uptake and storage site for all three metals. All of the uptake of new Zn and new Ni, and most of the uptake of new Ca into this tissue comes directly from the external water. For Zn, the mechanism involves only physicochemical processes, whereas for Ca and Ni, life-dependent processes make the major contribution.

Photocatalytic activity of ZnO doped Nano hydroxyapatite/GO derived from waste oyster shells for removal of Methylene blue.

Hydroxyapatite (HAp) stands as an inorganic compound, recognized as a non-toxic, bioactive ceramic, and its composition closely resembles that of bone material. In this study, nHAp was prepared from waste oyster shells, which are biowaste rich in calcium carbonate. nHAp with its unique catalytic property can be used as an adsorbent in various fields, including wastewater treatment. nHAp with an exceptional surface adsorbent with excellent chemical stability, enabling its catalytic function. Nano hydroxyapatite doped with Zinc oxide (ZnO) by wet chemical precipitation and made into a composite with Graphene oxide (GO) by modified hummers method followed by grinding, which was taken as 9:1 ratio (nHAp/ZnO and GO) of weight, enhances its tensile and mechanical strength. The energy band gap of nHAp photocatalyst was evaluated as 3.39 eV and that of the in nHAp/ZnO/GO photocatalyst was narrowed to 1.77 eV. The ternary nanocomposites are very efficient in generating the photogenerated electrons and holes, thereby improving the degradation potential of dye effluents to by-products such as CO2 and H2O. The nanocomposites photocatalyst were characterized by FTIR, XRD, SEM, TEM, EDS, XPS, DRS, and BET techniques. The UV-visible study shows the complete dye degradation efficiency of the prepared nanocomposites photocatalyst. In this study, the prepared nanocomposites nHAp/ZnO/GO have studied their efficiency for the removal of MB dye in a batch process by varying the dosage from 0.1 to 0.5 g, and the effects of dosage variations, pH, kinetic, scavenger study were evaluated at a time interval of 30 min. The removal of dye was found to be 99% at 150 min of 0.3 g dosage and pH = 12 is most favorable as it reached the same percentage at 90 min. The as-prepared nanocomposite nHAp/ZnO/GO fits the kinetic rate constant equation and shows a pseudo-first-order reaction model. This study indicates the suitability for dye removal due to the synergistic effect and electrostatic interaction of the synthesized ternary nanocomposite, which shows the potential, socially active, low-cost-effective, eco-friendly, and safe for photocatalytic degradation of MB from wastewater.

Dawn of diverse shelled and carbonaceous animal microfossils at ~ 571 Ma.

The Ediacaran-Cambrian transition documents a critical stage in the diversification of animals. The global fossil record documents the appearance of cloudinomorphs and other shelled tubular organisms followed by non-biomineralized small carbonaceous fossils and by the highly diversified small shelly fossils between ~ 550 and 530 Ma. Here, we report diverse microfossils in thin sections and hand samples from the Ediacaran Bocaina Formation, Brazil, separated into five descriptive categories: elongate solid structures (ES); elongate filled structures (EF); two types of equidimensional structures (EQ 1 and 2) and elongate hollow structures with coiled ends (CE). These specimens, interpreted as diversified candidate metazoans, predate the latest Ediacaran biomineralized index macrofossils of the Cloudina-Corumbella-Namacalathus biozone in the overlying Tamengo Formation. Our new carbonate U-Pb ages for the Bocaina Formation, position this novel fossil record at 571 ± 9 Ma (weighted mean age). Thus, our data point to diversification of metazoans, including biomineralized specimens reminiscent of sections of cloudinids, protoconodonts, anabaritids, and hyolithids, in addition to organo-phosphatic surficial coverings of animals, demonstrably earlier than the record of the earliest known skeletonized metazoan fossils.

Advancing responsible genomic analyses of ancient mollusc shells.

The analysis of the DNA entrapped in ancient shells of molluscs has the potential to shed light on the evolution and ecology of this very diverse phylum. Ancient genomics could help reconstruct the responses of molluscs to past climate change, pollution, and human subsistence practices at unprecedented temporal resolutions. Applications are however still in their infancy, partly due to our limited knowledge of DNA preservation in calcium carbonate shells and the need for optimized methods for responsible genomic data generation. To improve ancient shell genomic analyses, we applied high-throughput DNA sequencing to 27 Mytilus mussel shells dated to ~111-6500 years Before Present, and investigated the impact, on DNA recovery, of shell imaging, DNA extraction protocols and shell sub-sampling strategies. First, we detected no quantitative or qualitative deleterious effect of micro-computed tomography for recording shell 3D morphological information prior to sub-sampling. Then, we showed that double-digestion and bleach treatment of shell powder prior to silica-based DNA extraction improves shell DNA recovery, also suggesting that DNA is protected in preservation niches within ancient shells. Finally, all layers that compose Mytilus shells, i.e., the nacreous (aragonite) and prismatic (calcite) carbonate layers, with or without the outer organic layer (periostracum) proved to be valuable DNA reservoirs, with aragonite appearing as the best substrate for genomic analyses. Our work contributes to the understanding of long-term molecular preservation in biominerals and we anticipate that resulting recommendations will be helpful for future efficient and responsible genomic analyses of ancient mollusc shells.

Aplacophoran traits in the late Ordovician septemchitonid polyplacophorans.

A sample of phosphatized, originally calcareous, mollusk shells from the Katian age uppermost Mójcza Limestone at its type locality yielded a few hundred polyplacophoran plates. The chelodids are very rare among them. Three septemchitonid species dominate. They represent a gradation from underived steep roof-like plates to almost cylindrical ones, leaving only a narrow ventral slit for the foot. Apparently, this represents the first step toward the extremely derived 'segmented clam' Bauplan of the Silurian Carnicoleus, with plates completely closed at the venter except for the mouth and anal openings. To enable growth, the plates became thinner and more flexible (or perhaps resorbed) along the dorsum. The tendency toward reduction of the ventral gap of the plates in the early Paleozoic septemchitonid polyplacophorans implies their lack of ability to cling to the substrate with a muscular foot. In compensation, their plates changed toward a more efficient protective function, covering the animal body sides more and more completely. This may explain the origin of the ventral furrow of extant solenogasters hiding the rudimentary foot. An opposite route was chosen by the coeval Acaenoplax lineage, in which the plates did not contact each other, exposing much of the soft body on the dorsum. In both cases the animals appeared to be worm-like, perhaps representing different ways of evolution from the Paleozoic chitons to the extant aplacophorans.

Exploring the purity of chitin from crustacean sources using deep eutectic solvents: A machine learning approach.

OBJECTIVE: Chitin a natural polymer is abundant in several sources such as shells of crustaceans, mollusks, insects, and fungi. Several possible attempts have been made to recover chitin because of its importance in biomedical applications in various forms such as hydrogel, nanoparticles, nanosheets, nanowires, etc. Among them, deep eutectic solvents have gained much consideration because of their eco-friendly and recyclable nature. However, several factors need to be addressed to obtain a pure form of chitin with a high yield. The development of an innovative system for the production of quality chitin is of prime importance and is still challenging. METHODS: The present study intended to develop a novel and robust approach to investigate chitin purity from various crustacean shell wastes using deep eutectic solvents. This investigation will assist in envisaging the important influencing parameters to obtain a pure form of chitin via a machine learning approach. Different machine learning algorithms have been proposed to model chitin purity by considering the enormous experimental dataset retrieved from previously conducted experiments. Several input variables have been selected to assess chitin purity as the output variable. RESULTS: The statistical criteria of the proposed model have been critically investigated and it was observed that the results indicate XGBoost has the maximum predictive accuracy of 0.95 compared with other selected models. The RMSE and MAE values were also minimal in the XGBoost model. In addition, it revealed better input variables to obtain pure chitin with minimal processing time. CONCLUSION: This study validates that machine learning paves the way for complex problems with substantial datasets and can be an inexpensive and time-saving model for analyzing chitin purity from crustacean shells.

Insights into the mechanism of color formation of the freshwater prawn (Macrobrachium rosenbergii) revealed by de novo assembly transcriptome analysis.

Body color is an important visual indicator of crustacean quality and plays a major role in consumer acceptability, perceived quality, and the market price of crustaceans. The freshwater prawn (Macrobrachium rosenbergii) has two distinct phenotypic variations, characterized by dark blue and light yellow body colors. However, the underlying mechanisms regulating the body color of M. rosenbergii remain unclear. In this study, the composition of shell color parameters and pigment cells of raw and cooked dark blue and light yellow M. rosenbergii was investigated and the mechanisms associated with body color were elucidated by transcriptome analysis. The results showed significant differences in the raw shells of the dark blue and light yellow M. rosenbergii (L: 26.20 ± 0.53 vs. 29.25 ± 0.45; a: -0.88 ± 0.19 vs. 0.35 ± 0.18; b: 1.73 ± 0.20 vs. 3.46 ± 0.37; dE: 70.33 ± 0.53 vs. 67.34 ± 0.45, respectively, p = 0.000) as well as the cooked shells (L: 58.14 ± 0.81 vs. 55.78 ± 0.55; a: 19.30 ± 0.56 vs. 16.42 ± 0.40; b: 23.60 ± 0.66 vs. 20.30 ± 0.40, respectively, p < 0.05). Transcriptome differential gene analysis obtained 39.02 Gb of raw data and 158,026 unigenes. Comprehensive searches of the SwissProt, Nr, KEGG, Pfam, and KOG databases resulted in successful annotations of 23,902 (33 %), 40,436 (25.59 %), 32,015 (20.26 %), 26,139 (16.54 %), and 22,155 (14.02 %) proteins, respectively. By KEGG pathway analysis, numerous differentially expressed genes were related to pigmentation-related pathways (MAPK signaling pathway, Wnt signaling pathway, melanin production, tyrosine metabolism, and cell-cell communication process). Candidate DEGs that may be involved in body color included apolipoprotein D, crustacyanin, cytochrome P450, and tyrosinase, as verified by quantitative real-time PCR. The results of this study provide useful references to further elucidate the molecular mechanisms of color formation of M. rosenbergii and other crustaceans.

Elastic constants of biogenic calcium carbonate.

Living organisms form complex mineralized composite architectures that perform a variety of essential functions. These materials are commonly utilized for load-bearing purposes such as structural stability and mechanical strength in combination with high toughness and deformability, which are well demonstrated in various highly mineralized molluscan shell ultrastructures. Here, the mineral components provide the general stiffness to the composites, and the organic interfaces play a key role in providing these biogenic architectures with mechanical superiority. Although numerous studies employed state-of-the-art methods to measure and/or model and/or simulate the mechanical behavior of molluscan shells, our understanding of their performance is limited. This is partially due to the lack of the most fundamental knowledge of their mechanical characteristics, particularly, the anisotropic elastic properties of the mineral components and of the tissues they form. In fact, elastic constants of biogenic calcium carbonate, one of the most common biominerals in nature, is unknown for any organism. In this work, we employ the ultrasonic pulse-echo method to report the elasticity tensor of two common ultrastructural motifs in molluscan shells: the prismatic and the nacreous architectures made of biogenic calcite and aragonite, respectively. The outcome of this research not only provides information necessary for fundamental understanding of biological materials formation and performance, but also yields textbook knowledge on biogenic calcium carbonate required for future structural/crystallographic, theoretical and computational studies.

Middle through late Holocene long-distance transport of exotic shell personal adornments in Central West Patagonia (southern South America). The archaeomalacological assemblage of Baño Nuevo 1.

The exchange of information and social interactions on broad spatial scales between human groups in the past can be studied through the provenance of key indicators of distant origin recorded at archaeological sites. The remains of shells of mollusk species, especially when crafted as elements of personal ornaments, express aspects of the behaviors and valuations for the populations that selected, transformed, and exchanged such items. In the southern cone of South America, past hunter-gatherer groups traveled long distances and interacted with communities distributed throughout the territory to acquire goods for technological use, visual display or considered highly valued materials. When recorded at distant locations, these goods of extra local origin are very informative regarding the differences between commonly used home ranges and the occasional access to remote spaces. We present the results of the analysis of the archaeomalacological assemblage of the Baño Nuevo 1 site, a cave with exceptional preservation conditions in Central West Patagonia. This site has yielded a diverse group of artifacts made of shells with origins from multiple distances, as well as evidence of the use of marine, freshwater, and terrestrial species. Its deposits, which extend over the last 11,000 years, reveal an antiquity of at least the middle Holocene for the acquisition, manufacture, use and transport of goods as personal ornaments from shells in the macroregion.

Assessing phenotypic variation and plasticity of endemic gastropods from thermal water refugia using complex morphometric techniques: A case study of Lake Pețea melanopsids.

Understanding the underlying reasons for phenotypic plasticity and resulting morphological disparity is one of the key topics of evolutionary research. The phenotypic plasticity of extant and fossil melanopsids has been widely documented. Yet millennial-resolution, well-dated records from small aquatic habitats harboring endemics are scarce. The thermal spring-fed Lake Pețea is an ice age refugia harboring a unique endemic warm-water fauna. Subfossil melanopsids display incredible morphological variability from smooth to keeled, elongated to ribbed, shouldered forms. Numerous morphotypes have been considered as individual taxa with a fluent succession from the smooth elongated to the ribbed, shouldered types. This study presents an extensive morphometric analysis of subfossil melanopsids (ca. 3500 specimens) derived from stratified samples with an independent chronology. The aim was to separate morphotypes for investigations of temporal morphological disparity. Our results challenge the widely accepted hypothesis that proposes the evolution of shouldered, compressed, ribbed shells through a two-step process from smooth elongated spindle-shaped shells. Instead, it suggests that the subfossil shells belong to two distinct taxa present throughout the available stratigraphic data. The main components of shape variation, shape globularity, and shell coiling seem allometry-related. Ribs, striation, and keels appear randomly. High-spired spindle-shaped forms were considered to represent specimens of Microcolpia daudebartii hazayi. Bulkier low-spired and shouldered specimens represent phenotypes of Mi. parreyssii parreyssii. The collective and random distribution of morphotypes from the early stages of the lake's history also refutes the idea of a continuous transformation of the elongated forms into compressed, shouldered ones. Rather points to multiple events and environmental stimuli triggering development. Melanopsids appear in Late Glacial horizons, with Theodoxus prevostianus preferring temperatures above 23°C which may indicate the subordinate presence of hot water microhabitats in cooler waters.

Biomineral crystallographic preferred orientation in Solenogastres molluscs (Aplacophora) is controlled by organic templating.

Aplacophoran molluscs are shell-less and have a worm-like body which is covered by biomineralized sclerites. We investigated sclerite crystallography and the sclerite mosaic of the Solenogastres species Dorymenia sarsii, Anamenia gorgonophila, and Simrothiella margaritacea with electron-backscattered-diffraction (EBSD), laser-confocal-microscopy and FE-SEM imaging. The soft tissue of the molluscs is covered by spicule-shaped, aragonitic sclerites. These are sub-parallel to the soft body of the organism. We find, for all three species, that individual sclerites are untwinned aragonite single crystals. For individual sclerites, aragonite c-axis is parallel to the morphological, long axis of the sclerite. Aragonite a- and b-axes are perpendicular to sclerite aragonite c-axis. For the scleritomes of the investigated species we find different sclerite and aragonite crystal arrangement patterns. For the A. gorgonophila scleritome, sclerite assembly is disordered such that sclerites with their morphological, long axis (always the aragonite c-axis) are pointing in many different directions, being, more or less, tangential to cuticle surface. For D. sarsii, the sclerite axes (equal to aragonite c-axes) show a stronger tendency to parallel arrangement, while for S. margaritacea, sclerite and aragonite organization is strongly structured into sequential rows of orthogonally alternating sclerite directions. The different arrangements are well reflected in the structured orientational distributions of aragonite a-, b-, c-axes across the EBSD-mapped parts of the scleritomes. We discuss that morphological and crystallographic preferred orientation (texture) is not generated by competitive growth selection (the crystals are not in contact), but is determined by templating on organic matter of the sclerite-secreting epithelial cells and associated papillae.

Interpreting life-history traits, seasonal cycles, and coastal climate from an intertidal mussel species: Insights from 9000 years of synthesized stable isotope data.

Understanding past coastal variability is valuable for contextualizing modern changes in coastal settings, yet existing Holocene paleoceanographic records for the North American Pacific Coast commonly originate from offshore marine sediments and may not represent the dynamic coastal environment. A potential archive of eastern Pacific Coast environmental variability is the intertidal mussel species Mytilus californianus. Archaeologists have collected copious stable isotopic (δ18O and δ13C) data from M. californianus shells to study human history at California's Channel Islands. When analyzed together, these isotopic data provide windows into 9000 years of Holocene isotopic variability and M. californianus life history. Here we synthesize over 6000 δ18O and δ13C data points from 13 published studies to investigate M. californianus shell isotopic variability across ontogenetic, geographic, seasonal, and millennial scales. Our analyses show that M. californianus may grow and record environmental information more irregularly than expected due to the competing influences of calcification, ontogeny, metabolism, and habitat. Stable isotope profiles with five or more subsamples per shell recorded environmental information ranging from seasonal to millennial scales, depending on the number of shells analyzed and the resolution of isotopic subsampling. Individual shell profiles contained seasonal cycles and an accurate inferred annual temperature range of ~ 5°C, although ontogenetic growth reduction obscured seasonal signals as organisms aged. Collectively, the mussel shell record reflected millennial-scale climate variability and an overall 0.52‰ depletion in δ18Oshell from 8800 BP to the present. The archive also revealed local-scale oceanographic variability in the form of a warmer coastal mainland δ18Oshell signal (-0.32‰) compared to a cooler offshore islands δ18Oshell signal (0.33‰). While M. californianus is a promising coastal archive, we emphasize the need for high-resolution subsampling from multiple individuals to disentangle impacts of calcification, metabolism, ontogeny, and habitat and more accurately infer environmental and biological patterns recorded by an intertidal species.

Adsorption properties of Pb(II) and Cd(II) in acid mine drainage by oyster shell loaded lignite composite in different morphologies.

A new idea to alleviate environmental pollution is the development of low-cost adsorbents using natural minerals and fishery wastes to treat high concentrations of heavy metal pollutants in acid mine drainage (AMD). Adsorbent morphology, adsorptive and regenerative capacity, and application potential are limiting factors for their large-scale use. Oyster shells capable of releasing alkalinity were loaded on the surface of lignite to develop two composite adsorbents with different morphologies (powdery and globular) for the treatment of AMD containing Pb(II) and Cd(II). The results show that the ability of the adsorbent to treat AMD is closely related to its morphologies. The pseudo-second-order kinetic model and the Langmuir model are suitable to describe the adsorption process of OS-M(P), and the maximum adsorption saturation capacities of Pb(II) and Cd(II) are 332.6219 mg/g and 318.9854 mg/g, respectively. The pseudo-second-order kinetic model and the Freundlich model are suitable to describe the adsorption process of OS-M(G). A synergistic result of electrostatic adsorption, neutralization precipitation, ion exchange and complex reaction is achieved in the removal of Pb(II) and Cd(II) by two morphologies of adsorbents. The regeneration times (5 times) and recovery rate (75.75%) of OS-M(G) are higher than those of OS-M(P) (3 times) and recovery rate (20%). The ability of OS-M(G) to treat actual AMD wastewater is still better than that of OS-M(P). OS-M(G) can be used as a promising environmentally friendly adsorbent for the long-term remediation of AMD. This study provides a comprehensive picture of resource management and reuse opportunities for natural mineral and fishery wastes.

Modulation of host lipid metabolism by virus infection leads to exoskeleton damage in shrimp.

The arthropod exoskeleton provides protection and support and is vital for survival and adaption. The integrity and mechanical properties of the exoskeleton are often impaired after pathogenic infection; however, the detailed mechanism by which infection affects the exoskeleton remains largely unknown. Here, we report that the damage to the shrimp exoskeleton is caused by modulation of host lipid profiles after infection with white spot syndrome virus (WSSV). WSSV infection disrupts the mechanical performance of the exoskeleton by inducing the expression of a chitinase (Chi2) in the sub-cuticle epidermis and decreasing the cuticle chitin content. The induction of Chi2 expression is mediated by a nuclear receptor that can be activated by certain enriched long-chain saturated fatty acids after infection. The damage to the exoskeleton, an aftereffect of the induction of host lipogenesis by WSSV, significantly impairs the motor ability of shrimp. Blocking the WSSV-caused lipogenesis restored the mechanical performance of the cuticle and improved the motor ability of infected shrimp. Therefore, this study reveals a mechanism by which WSSV infection modulates shrimp internal metabolism resulting in phenotypic impairment, and provides new insights into the interactions between the arthropod host and virus.

Effects of crayfish shell powder and bamboo-derived biochar on nitrogen conversion, bacterial community and nitrogen functional genes during pig manure composting.

This study investigated the effects of crayfish shell powder (CSP) and bamboo-derived biochar (BDB) on nitrogen metabolism, bacterial community and nitrogen functional genes during pig manure composting. Four treatments were established: CP (with no additives), TP1 (5 % BDB), TP2 (5 % CSP) and TP3 (2.5 % BDB + 2.5 % CSP). Compared to CP, the germination index (GI) of TP reached > 85 % 10 days earlier. Meanwhile, TP3 reduced NH3 and N2O emissions by 42.90 % and 65.9 %, respectively, while increased TN (total nitrogen) concentration by 5.43 g/kg. Furthermore, additives changed the bacterial structure and formed a beneficial symbiotic relationship with essential N-preserving bacteria, thereby enhancing nitrogen retention throughout the composting process. Metagenomic analysis revealed that additives upregulated nitrification genes and downregulated denitrification and nitrate reduction genes, ultimately improving nitrogen cycling and mitigating NH3 and N2O emissions. In conclusion, the results confirmed that TP3 was the most effective treatment in reducing nitrogen loss.

Azithromycin removal using pine bark, oak ash and mussel shell.

Adsorption is considered an interesting option for removing antibiotics from the environment because of its simple design, low cost, and potential efficiency. In this work we evaluated three by-products (pine bark, oak ash, and mussel shell) as bio-adsorbents for the antibiotic azithromycin (AZM). Furthermore, they were added at doses of 48 t ha-1 to four different soils, then comparing AZM removal for soils with and without bio-adsorbents. Batch-type experiments were used, adding AZM concentrations between 2.5 and 600 µmol L-1 to the different bio-adsorbents and soil + bio-adsorbent mixtures. Regarding the bio-adsorbents, oak ash showed the best adsorption scores (9600 µmol kg-1, meaning >80% retention), followed by pine bark (8280 µmol kg-1, 69%) and mussel shell (between 3000 and 6000 µmol kg-1, 25-50% retention). Adsorption data were adjusted to different models (Linear, Freundlich and Langmuir), showing that just mussel shell presented an acceptable fitting to the Freundlich equation, while pine bark and oak ash did not present a good adjustment to any of the three models. Regarding desorption, the values were always below the detection limit, indicating a rather irreversible adsorption of AZM onto these three by-products. Furthermore, the results showed that when the lowest concentrations of AZM were added to the not amended soils they adsorbed 100% of the antibiotic, whereas when the highest concentrations of AZM were spread, the adsorption decreased to 55%. However, when any of the three bio-adsorbents was added to the soils, AZM adsorption reached 100% for all the antibiotic concentrations used. Desorption was null in all cases for both soils with and without bio-adsorbents. These results, corresponding to an investigation carried out for the first time for the antibiotic AZM, can be seen as relevant in the search of low-cost alternative treatments to face environmental pollution caused by this emerging contaminant.