Bending and branching of calcite laths in the foliated microstructure of pectinoidean bivalves occurs at coherent crystal lattice orientation.

Foliated calcite is widely employed by some important pteriomorph bivalve groups as a construction material. It is made from calcite laths, which are inclined at a low angle to the internal shell surface, although their arrangement is different among the different groups. They are strictly ordered into folia in the anomiids, fully independent in scallops, and display an intermediate arrangement in oysters. Pectinids have particularly narrow laths characterized by their ability to change their growth direction by bending or winding, as well as to bifurcate and polyfurcate. Electron backscatter analysis indicates that the c-axes of laths are at a high, though variable, angle to the growth direction, and that the laths grow preferentially along the projection of an intermediate axis between two a-axes, although they can grow in any intermediate direction. Their main surfaces are not particular crystallographic faces. Analyses done directly on the lath surfaces demonstrate that, during the bending/branching events, all crystallographic axes remain invariant. The growth flexibility of pectinid laths makes them an excellent space-filling material, well suited to level off small irregularities of the shell growth surface. We hypothesize that the exceptional ability of laths to change their direction may be promoted by the mode of growth of biogenic calcite, from a precursor liquid phase induced by organic molecules.

The demographic consequences of growing older and bigger in oyster populations.

Structured population models, particularly size- or age-structured, have a long history of informing conservation and natural resource management. While size is often easier to measure than age and is the focus of many management strategies, age-structure can have important effects on population dynamics that are not captured in size-only models. However, relatively few studies have included the simultaneous effects of both age- and size-structure. To better understand how population structure, particularly that of age and size, impacts restoration and management decisions, we developed and compared a size-structured integral projection model (IPM) and an age- and size-structured IPM, using a population of Crassostrea gigas oysters in the northeastern Pacific Ocean. We analyzed sensitivity of model results across values of local retention that give populations decreasing in size to populations increasing in size. We found that age- and size-structured models yielded the best fit to the demographic data and provided more reliable results about long-term demography. Elasticity analysis showed that population growth rate was most sensitive to changes in the survival of both large (>175 mm shell length) and small (<75 mm shell length) oysters, indicating that a maximum size limit, in addition to a minimum size limit, could be an effective strategy for maintaining a sustainable population. In contrast, the purely size-structured model did not detect the importance of large individuals. Finally, patterns in stable age and stable size distributions differed between populations decreasing in size due to limited local retention and populations increasing in size due to high local retention. These patterns can be used to determine population status and restoration success. The methodology described here provides general insight into the necessity of including both age- and size-structure into modeling frameworks when using population models to inform restoration and management decisions.

Hemolymph chemistry and histopathological changes in Pacific oysters (Crassostrea gigas) in response to low salinity stress.

This study described seasonal differences in the histopathological and hemolymph chemistry changes in different family lines of Pacific oysters, Crassostrea gigas, in response to the stress of an abrupt change to low salinity, and mechanical grading. The most significant changes in pallial cavity salinity, hemolymph chemistry and histopathological findings occurred in summer at low salinity. In summer (water temperature 18°C) at low salinity, 9 (25.7% of full salinity), the mean pallial cavity salinity in oysters at day 3 was 19.8±1.6 (SE) and day 10 was 22.8±1.6 (SE) lower than oysters at salinity 35. Associated with this fall in pallial cavity salinity, mean hemolymph sodium for oysters at salinity 9 on day 3 and 10 were 297.2mmol/L±20(SE) and 350.4mmol/L±21.3(SE) lower than oysters at salinity 35. Similarly mean hemolymph potassium in oysters held at salinity 9 at day 3 and 10 were 5.6mmol/L±0.6(SE) and 7.9mmol/L±0.6 (SE) lower than oysters at salinity 35. These oysters at low salinity had expanded intercellular spaces and significant intracytoplasmic vacuolation distending the cytoplasm of epithelial cells in the alimentary tract and kidney and hemocyte infiltrate (diapedesis) within the alimentary tract wall. In contrast, in winter (water temperature 8°C) oyster mean pallial cavity salinity only fell at day 10 and this was by 6.0±0.6 (SE) compared to that of oysters at salinity 35. There were limited histopathological changes (expanded intercellular spaces and moderate intracytoplasmic vacuolation of renal epithelial cells) in these oysters at day 10 in low salinity. Mechanical grading and family line did not influence the oyster response to sudden low salinity. These findings provide additional information for interpretation of non-lethal, histopathological changes associated with temperature and salinity variation.

Taxonomic review, palaeoecological, and palaeobiogeographical significances of Campanian Tethyan oysters from the North Eastern Desert, Egypt.

The Late Cretaceous was a time of high eustatic sea level that enabled extensive epicontinental seaways and carbonate platforms across the Tethyan Realm, providing favorable habitats for oyster communities to flourish. This study focuses on the Campanian Tethyan oysters from the North Eastern Desert of Egypt regarding taxonomy, palaeoecology, and palaeobiogeography. Three oyster species, Nicaisolopha nicaisei (Coquand, 1862), Pycnodonte (Phygraea) vesicularis (Lamarck, 1806), and Ambigostrea bretoni (Thomas and Peron, 1891), were identified from the Campanian succession in two studied sections. The sampled specimens of the genus Nicaisolopha have undergone a systematic palaeontological revision. As a result, N. tissoti (Thomas and Peron, 1891) is considered herein a junior synonym of N. nicaisei (Coquand, 1862). Palaeobiogeographically, the likely primary migration pattern of the studied oysters suggests an east-west trend along the Southern Tethys margin. All identified oysters in this study exhibit a Tethyan affinity and are primarily abundant in two main provinces: the Southern Tethys and the Western Tethys. The macrofaunal contents are categorized into two fossil associations: the Nicaisolopha nicaisei association of the middle-late Campanian age and the Pycnodonte vesicularis association of the late Campanian age. These macrofaunal associations indicate a deepening trend during the middle-late Campanian age, suggesting a transition from shallow inner neritic to middle neritic environments. Additionally, it is observed that Pycnodonteinae tend to grow larger under eutrophic conditions, low-energy environments, and nutrient-rich waters with high carbonate contents.

The recycling of oyster shells: an environmental analysis using Life Cycle Assessment.

Oysters represent a substantial fraction of the world's overall intensive aquaculture production. In Brazil, oyster aquaculture is still in the deployment phase but has the potential for growth and, likewise other aquaculture products, generate environmental impacts over their life cycle. Special attention should be devoted to the disposal or processing of the oyster shells, whose high calcium carbonate content (80-95%) gives them the potential for use as raw material for several other products. The objective of this study was to conduct a cradle-to-grave Life Cycle Assessment (LCA) of 1 kg of oysters produced in southern Brazil, incorporating the recycling of the oyster shells on the LCA. Two scenarios were considered. The first scenario (termed scenario A) assumed that the oyster shells were deposited in a landfill, whereas the second scenario (scenario B) assumed that the shells were processed to make them available as raw material as a source of CaCO(3). We used Eco-indicator 99 H/A to perform the impact assessment. Scenario A had an overall impact of 93.71 mPt, whereas scenario B had an overall impact of 58.97 mPt. The latter scenario had lower environmental impacts, however they were depended strongly on the distance between the source of the shells (restaurant) and the shell-processing facility. This distance must not be greater than 323 km to yield overall environmental benefits. Moreover, it is hypothesized that the environmental benefits would be even higher than predicted because there is no evidence that all post-consumer shell residues would receive proper waste management, as assumed for scenario A (landfill).

Composted oyster shell as lime fertilizer is more effective than fresh oyster shell.

Physio-chemical changes in oyster shell were examined, and fresh and composted oyster shell meals were compared as lime fertilizers in soybean cultivation. Structural changes in oyster shell were observed by AFM and FE-SEM. We found that grains of the oyster shell surface became smoother and smaller over time. FT-IR analysis indicated the degradation of a chitin-like compound of oyster shell. In chemical analysis, pH (12.3+/-0.24), electrical conductivity (4.1+/-0.24 dS m(-1)), and alkaline powder (53.3+/-1.12%) were highest in commercial lime. Besides, pH was higher in composted oyster shell meal (9.9+/-0.53) than in fresh oyster shell meal (8.4+/-0.32). The highest organic matter (1.1+/-0.08%), NaCl (0.54+/-0.03%), and moisture (15.1+/-1.95%) contents were found in fresh oyster shell meal. A significant higher yield of soybean (1.33 t ha(-1)) was obtained by applying composted oyster shell meal (a 21% higher yield than with fresh oyster shell meal). Thus composting of oyster shell increases the utility of oyster shell as a liming material for crop cultivation.

Regression of the level of different heavy metals to size of marine organisms harvested from the "Jiyeh" oil spill zone of the eastern Mediterranean Sea.

This study aimed to establish a baseline data on regression of the levels of Lead (Pb), Nickel (Ni) and Vanadium (V) to specific size dimensions of selected marine organisms harvested from an oil spill zone of the Eastern Mediterranean Sea. Twenty samples of each of Siganus rivulatus, Mullets and oysters were collected from each of six harvest sites. A total of 1, 3, and 3 respective significant regression equations (p < 0.01) were established between Pb, Ni, V and specific size dimensions of the selected marine organisms. The significant correlation associated with the highest R (2) value was obtained between the Pb (y) level and the width (x) of the Siganus rivulatus (y = -86.833x + 417.72). The other six statistically significant correlations were associated with lower values of R (2) ranging between 0.338 and 0.380. This baseline data will be used in the future to evaluate the self-purification process of pollutants in different sizes of indicator-marine organisms in this part of the Mediterranean Sea.

Morphology of nutrient storage cells in the gonadal area of the Pacific oyster, Crassostrea gigas (Thunberg, 1793).

Successful gametogenesis in invertebrates is tightly associated with functioning of specific nutrient-storing cells. In oysters, cells of vesicular connective tissue (VCT-cells), also referred to as storage cells, which form a meshwork around gonadal acini, are the major population of cells that accumulate and provide nutrients for developing gametes. During the annual reproductive cycle, populations of developing germ cells and VCT-cells demonstrate the inversely proportional size dynamics: the larger the acini, the smaller the VCT-cells. In the present study, the morphology of VCT-cells in the Pacific oyster, Crassostrea gigas, at the active gametogenesis stage of reproductive cycle has been studied using light and transmission electron microscopy. At this stage, VCT-cells are big, irregularly shaped cells containing large nucleus with a single large nucleolus. The cytoplasm contains weakly developed endoplasmic reticulum, mitochondria in the perinuclear area and at periphery of the cell, numerous lipid droplets, and glycogen particles. Ultrastructure of VCT-cells is similar to the organization of brown adipocytes in mammals. The surface of cells has numerous cytoplasmic processes that are presumably associated with the transport function and provide close interaction with adjacent cells. The spatial relationship between VCT-cells and myoepithelial elements of the gonad area is demonstrated and discussed.

Distribution of butyltin and derivatives in oyster shells and trapped sediments of two estuaries in Cantabria (Northern Spain).

Distribution of butyltin compounds (BTs) and derivatives (monobutyltin, MBT; dibutyltin, DBT and tributyltin, TBT) was analysed in Crassostrea gigas oyster shells and the sediments trapped in the shell chambers, from two different estuaries in Cantabria (Northern Spain), with very different environmental conditions, where previous data have not been reported. Inorganic tin analysis in oyster shells was performed in order to study the degradation of BTs. Shell thickening and losses in biological growth are related with the presence of TBT, and were determined using three morphological indexes. Total BTs concentrations, expressed as Sn, ranged from 18.0 ng g(-1) to 176.7 ng g(-1) in sediments, and from 2.4 ng g(-1) to 11.1 ng g(-1) in oyster shells. Total inorganic tin concentrations ranged from 1775.0 ng g(-1) to 4781.3 ng g(-1) in oyster shells. The amount of BTs in oyster shells has been associated with the concentrations in the sediments trapped in the shell chambers. Partition coefficients between oyster sediments and oyster shells show the affinity of BTs by the sediments and the higher inorganic tin in oyster shells does not seem to be related to the BTs pollution.

cDNA cloning and characterization of a novel calmodulin-like protein from pearl oyster Pinctada fucata.

Calcium metabolism in oysters is a very complicated and highly controlled physiological and biochemical process. However, the regulation of calcium metabolism in oyster is poorly understood. Our previous study showed that calmodulin (CaM) seemed to play a regulatory role in the process of oyster calcium metabolism. In this study, a full-length cDNA encoding a novel calmodulin-like protein (CaLP) with a long C-terminal sequence was identified from pearl oyster Pinctada fucata, expressed in Escherichia coli and characterized in vitro. The oyster CaLP mRNA was expressed in all tissues tested, with the highest levels in the mantle that is a key organ involved in calcium secretion. In situ hybridization analysis reveals that CaLP mRNA is expressed strongly in the outer and inner epithelial cells of the inner fold, the outer epithelial cells of the middle fold, and the dorsal region of the mantle. The oyster CaLP protein, with four putative Ca(2+)-binding domains, is highly heat-stable and has a potentially high affinity for calcium. CaLP also displays typical Ca(2+)-dependent electrophoretic shift, Ca(2+)-binding activity and significant Ca(2+)-induced conformational changes. Ca(2+)-dependent affinity chromatography analysis demonstrated that oyster CaLP was able to interact with some different target proteins from those of oyster CaM in the mantle and the gill. In summary, our results have demonstrated that the oyster CaLP is a novel member of the CaM superfamily, and suggest that the oyster CaLP protein might play a different role from CaM in the regulation of oyster calcium metabolism.

There Is More than One Way to Crack an Oyster: Identifying Variation in Burmese Long-Tailed Macaque (Macaca fascicularis aurea) Stone-Tool Use.

We explored variation in patterns of percussive stone-tool use on coastal foods by Burmese long-tailed macaques (Macaca fascicularis aurea) from two islands in Laem Son National Park, Ranong, Thailand. We catalogued variation into three hammering classes and 17 action patterns, after examining 638 tool-use bouts across 90 individuals. Hammering class was based on the stone surface used for striking food, being face, point, and edge hammering. Action patterns were discriminated by tool material, hand use, posture, and striking motion. Hammering class was analyzed for associations with material and behavioural elements of tool use. Action patterns were not, owing to insufficient instances of most patterns. We collected 3077 scan samples from 109 macaques on Piak Nam Yai Island's coasts, to determine the proportion of individuals using each hammering class and action pattern. Point hammering was significantly more associated with sessile foods, smaller tools, faster striking rates, smoother recoil, unimanual use, and more varied striking direction, than were face and edge hammering, while both point and edge hammering were significantly more associated with precision gripping than face hammering. Edge hammering also showed distinct differences depending on whether such hammering was applied to sessile or unattached foods, resembling point hammering for sessile foods and face hammering for unattached foods. Point hammering and sessile edge hammering compared to prior descriptions of axe hammering, while face and unattached edge hammering compared to pound hammering. Analysis of scans showed that 80% of individuals used tools, each employing one to four different action patterns. The most common patterns were unimanual point hammering (58%), symmetrical-bimanual face hammering (47%) and unimanual face hammering (37%). Unimanual edge hammering was relatively frequent (13%), compared to the other thirteen rare action patterns (<5%). We compare our study to other stone-using primates, and discuss implications for further research.

Interface between bone and nacre implants in sheep.

We have investigated the interface between bone and chronic implants of nacre in sheep. There was no foreign body reaction over the period of 10 months and the implants were not broken down. Light microscopy indicated activity within an osteoprogenitor cellular layer lining the implant, resulting in a complete sequence of new bone formation. Nacre appeared to bind directly to newly formed bone without any intervening fibrous tissue. Scanning electron microscopy and energy dispersive photon X-microanalysis showed calcium and phosphate ions lining the nacre within the osteoprogenitor tissue. These studies show a dynamic activity of the bone/nacre interface, leading to continuity between the nacre and the bone.

Storage metabolism in the Pacific oyster (Crassostrea gigas) in relation to summer mortalities and reproductive cycle (west coast of France).

We describe seasonal changes in the biochemical composition of digestive gland, adductor muscle and gonad and surrounding mantle area in Crassostrea gigas from the Western Atlantic coast of France. Seasonality in histology of storage tissues and glycogen storage capacity in isolated vesicular cells were also studied. Proteins, the main muscle components did not contribute to the gametogenetic effort. Glycogen and lipids were stored in the digestive gland, gonad and surrounding mantle area during the wintering period and the gonad and surrounding mantle area represented the main storage compartment supplying the reproductive effort. Gametogenesis in spring and summer was associated with an increase in lipid and protein contents and took place at the expense of glycogen reserves. Histological study of storage tissue in the gonad led us to define four seasonal stages of storage tissue development. In vitro, glycogen storage capacity in isolated vesicular cells was high from November to March and markedly reduced during gametogenesis, decreasing below detectable levels after spawning. This physiological state should be taken into account with relation to summer mortalities occurring in commercial growing areas.

Environmental impact of TBT: the French experience.

The deleterious effects of TBT released by antifouling paints were first documented in Arcachon Bay (France) at the end of the 1970s. As a result of the high level of water contamination, the production of Pacific oysters was severely affected by a complete lack of reproduction and the appearance of calcification anomalies which were responsible for a strong decline in the marketable value of the remaining stock. Regulations that had been successively adopted from January 1982 had positive effects on the recovery of the oyster grounds by reducing ambient water concentrations. Most antifouling paints act by releasing toxicants into the water which avoid the fixation of the organisms responsible for fouling. The use of these paints results in significant inputs of biocides in the waters. The harmful effects on non-target organisms were first evidenced in the bay of Arcachon (France) where the most acute disturbances were recorded following tributyltin (TBT) contamination.

Evaluation of environmental levels and biological impact of TBT in Malta (central Mediterranean).

Chemical monitoring for butyltins in bulk seawater, surface microlayer and superficial sediments determined that the two main local sources of marine contamination by tributyltin (TBT) compounds in Malta are ship-repairing dockyards and marinas. In bulk seawater, TBT values ranged from below the detection limit of 5 ng Sn l(-1) to 300 ng Sn l(-1); in sediments derived from the most polluted areas, TBT concentrations as high as 1500 ng Sn g(-1) were measured. At TBT levels found in local harbours, several sublethal biological responses are possible and were observed, including a significant reduction in MFO enzyme system activities of fish; digestive cell atrophy in the oyster Ostrea edulis; and induction of imposex in the snail Hexaplex trunculus. The latter two responses are evident at TBT concentrations below the environmental quality standard (20 ng TBT l(-1)). The ecological implications of these results are discussed and it is concluded that exposure of marine organisms to TBT in local harbours may be expected to lead to a reduction in the long-term survival of a number of such organisms. For these reasons, both the use of TBT-based antifouling paints for pleasure boats as well as drydock practices need to be controlled by appropriate regulations and their enforcement.

[Somatic production of two species: Crassostrea virginica and Ischadium recurvum Bivalvia in Mecoacán, Tabasco, México]. / Producción somática de dos especies de Crassostrea virginica e Ischadium recurvum (Bivalvia) en Mecoacán, Tabasco, México.

The Mexican oyster fishery, 90% supported by the coastal lagoons of the Gulf of Mexico, has decreased drastically in the last six years as a result of anthropogenic pollution and improper management. The mussel Ischadium recurvum has proliferated and competes with oysters for space and probably food. Crassostrea virginica and Ischadium recurvum were studied to evaluate somatic production with biometry and physiological condition indices (PCI's) during an annual cycle. A random sample of 200 organisms was taken montly for each species. Condition indices wet flesh weigth: wet shell weight ratio (WFW/WSW), dry flesh weight: wet flesh weight ratio (DFW/WFW), dry flesh wet: dry shell weight ratio (DFW/DSW), and ash free dry weight: tissue dry weight (AFDW/TDW) were calculated. In order to stablish physiological condition and temporal variability, these indices were compared between species and months. The somatic production of mussels was higher than in oysters. This enhancement in production could be explained by: 1) Mussel uses less energy for shell production, 2) a constant recruitment of mussel almost year-round, and 3) the mesohalin lagoon was more favourable to the mussel.

[Availabilty of juveniles from natural sources of the oyster Pteria colymbus (Bivalvia: Mytilidae), in the Gulf of Cariaco, Venezuela]. / Disponibilidad de juveniles por captación natural de la ostra Pteria colymbus (Bivalvia: Pteriidae) en el Golfo de Cariaco, Venezuela.

We examined the spat availability the oyster Pteria colymbus at 6-8 and 19-21 m depths for 15 months (March 1993-June 1994) in Turpialito, Golfo de Cariaco, Venezuela. Spats were trapped using artificial collectors (plastic filaments in bags, 30 x 60 mm), suspended from a long line. Each collector was replaced by a replica monthly to analyse abundance, shell dimension and mass of P. colymbus. Intraweekly, the temperature, salinity, oxygen and food availability (Chlorophyll a, total seston, organic and inorganic seston) were determinated. There is juvenile recruitment all year, suggesting continuous reproduction. Spat counts were higher at 6-8 m (generally 50-230 juveniles per collector) with peaks in August and December 1993 (April and June 93 at 19-21 m). The length-weigh mass relation was higher at 19-21 m, suggesting greater food availability because of lower organism density (including P. colymbus) and a greater water flux. Phytoplanktonic abundance and temperature were correlated (r2=0.38) with juvenile abundanc; this relationship and the association of juvenile abundance with higher temperature and Chlorophyll a levels, suggest that spat abundance was higher at the beginning of the water stratification period, when phytoplankton biomass is high.

Metagenomic characterization of oyster shell dump reveals predominance of Firmicutes bacteria.

Metagenomic analyses were conducted to evaluate the biodiversity of oyster shell bacteria, under storage conditions, on the basis of 16s rDNA sequences. Temperature was recorded during a one year storage period, and the highest temperature (about 60 degrees C) was observed after five months ofstorage. Bacterial diversity was greatest in the initial stage sample, with 33 different phylotypes classified under seven phyla (Proteobacteria, Bacteroidetes, Firmicutes, Actinobacteria, Planctomycetes, Verrucomicrobia and unclassified bacteria), with 42.22% ofphylotypes belonging to Proteobacteria. The lowest diversity was found in the high temperature (fermentation) stage sample, with 10 different phylotypes belonging to Firmicutes (78.57%) and Bacteroidetes. In the final stage sample, bacteria were found belonging to Proteobacteria, Bacteroidetes, and Firmicutes, and some were unclassified bacteria. Of the bacteria constituting the final stage metagenome, 69.70% belonged to Firmicutes. Our results show that bacteria belonging to phylum Firmicutes were predominant during fermentation, and during the final stages of oyster shell storage, which suggests that these bacteria supposed to be the key players for oyster shell biodegradation.

[Asymmetry and growth rate of the shell valves in juveniles of Crassostrea gigas Thünberg]. / Dissymétrie et taux de croissance des valves de la coquille chez les jeunes huîtres de Crassostrea gigas Thünberg.

Thanks to a sampling of juvenile oysters with different growth rates (slow, medium and fast), a subtle biometrical study of their shell evolution is described distinguishing the two valves. We conclude that all the phenomena are dominated by the early establishment of a directional asymmetry, which rapidly becomes so large that we should consider dissymmetry. The clearest relationship is revealed to be that between the weakness of the growth rate and the degree of the relative dissymetry between the weights of the valves. This result is to be compared with the highly debated relationship between the asymmetry and the growth rate. The existence and interpretation of both of these phenomena have led to many publications.