Maximum Shell Research Articles

Growth and Longevity of the „Living fossil”Congeria kusceri(Bivalvia: Dreissenidae) from the Subterranean Dinaric Karst of Croatia

The present study analyzed growth and longevity of the endemic cave dwelling bivalve Congeria kusceri obtained from the pit Jama u Predolcu, Croatia. A water temperature of 13–14°C constituted the lower limit for shell growth of C. kusceri. Obtained data also indicated that enhanced calcium uptake by C. kusceri during its summer growth and reproductive phases coincided with a decrease in alkalinity of the pit water. An analysis of shell growth rings in C. kusceri has identified an impressive longevity of 53 years. Calculations of growth rate suggested maximum theoretical shell lengths (L∞) of 16.7 mm for males and 18.7 mm for females and a growth constant of 0.04 year-1 for both sexes. Congeria kusceri can, however, grow to a shell length of > 24 mm, suggesting that longevity of this species could be greater than that identified in this study. The obtained results add to our understanding of how colonisation and continued and successful occupation of a subterranean freshwater habitat has been achieved.

Effect of the deflection strain on the atomic and electronic structure of a graphene nanoparticle

The results of numerical simulation of the deflection strain of a graphene nanoparticle 36.9 A long and 41.18 A wide are presented. The nanoparticle is deflected by nanoindentation. A platinum pyramid with the face-centered cubic lattice is considered as an atomic-force microscope tip. It is found that the graphene nanoparticle withstands a force of 437.83 nN, and its tensile strength is 126 GPa. It is shown that the nanoparticle deflection improves its emission properties. The particle conductivity remains almost unchanged with increasing deflection. The maximum π-electron shell overlap and the significant redistribution of the electron charge density are characteristic of atoms of the graphene nanoparticle with the largest curvature.

Use of probiotic bacteria to improve growth and survivability of farmed New Zealand abalone (Haliotis iris)

The effects of two probiotic feeds containing two and three bacterial isolates were evaluated on the growth performance of New Zealand abalone (Haliotis iris). Probiotic bacteria were isolated from the guts of healthy adult abalone. The isolates were screened qualitatively and quantitatively according to their ability to hydrolyse nutrients (i.e. proteins, starch and alginate), produce acid and resist bile salts. Based on the screening results, we developed a multi-strain conglomerate of 2- and 3- probiotic bacterial strains that were supplemented into a commercial abalone feed to use in our experiments. The 2-probiotic conglomerate consisted of Exiguobacterium JHEb1 and Vibrio JH1, and the 3-probiotic conglomerate consisted of Exiguobacterium JHEb1, Vibrio JH1 and Enterococcus JHLDc. The probiotic feeding trial involved abalone juveniles (20–30 mm in maximum shell length). Both probiotic feeds significantly improved abalone growth compared to that of the unsupplemented feed. The 3-probiotic supplemented feed produced a significant shell length increase of 20.9%, a wet weight gain of 19.8% and a five-fold reduction in mortality compared to the controls. The 2-probiotic supplemented feed resulted in significant increases in shell length (15.4%) and reduced mortality (five-fold), but not in weight gain, compared to controls.

Testing the effects of temporal data resolution on predictions of the effects of climate change on bivalves

The spatial–temporal scales on which environmental observations are made can significantly affect our perceptions of ecological patterns in nature. Understanding potential mismatches between environmental data used as inputs to predictive models, and the forecasts of ecological responses that these models generate are particularly difficult when predicting responses to climate change since the assumption of model stationarity in time cannot be tested. In the last four decades, increases in computational capacity (by a factor of a million), and the evolution of new modeling tools, have permitted a corresponding increase in model complexity, in the length of the simulations, and in spatial–temporal resolution. Nevertheless, many predictions of responses such as shifts in range boundaries are often based on coarse spatial and temporal data, for example monthly or yearly averages. Here we model the effects of environmental change on the physiological response of an ecologically and commercially important species of mussel, the fitness of which can have a cascading influence on ecosystem levels. Using a Dynamic Energy Budget (DEB) model integrated with climatic data produced from IPCC-A1B scenarios, we investigated the effect of temporal resolution of physical data on predictions of the growth and reproductive output of the mussel Mytilus galloprovincialis. We ran models using five different temporal scales, 6, 4, 3, 2 and 1h (derived by interpolating between 6h points), at 5 Italian locations in the Central Mediterranean Sea, for the period ranging from 2006 to 2009. Results from these models were further compared against the results from a DEB model that used hourly environmental data recorded at the five locations as inputs. Model outputs included estimates of life history traits relevant to ecological performance as well as parameters related to Darwinian fitness. Results showed that predictions of maximum theoretical shell length were similar regardless of which source of environmental data was used. However, while the DEB model using 1-h modeled data produced predictions of reproductive output very similar to those obtained using recorded (hourly) environmental data from the same time period, results using coarser resolution modeled data greatly underestimated reproductive output. Thus, the use of modeled weather data can yield predictions similar to those generated from measured data, but only when data are provided at relatively high frequency. Our results suggest that metrics of model skill can diverge significantly when physical outputs of climate models are applied to biological questions, and that the temporal resolution of environmental data can strongly alter predictions of biological responses to environmental change.

Population structure of the protected fan musselPinna nobilisin the south Aegean Sea (eastern Mediterranean)

Pinna nobilisis an endemic Mediterranean species of high economic and cultural importance. Nowadays, it is under strict protection as a dramatic decline in its populations has been recognized, assigned to the combined effect of fisheries and habitat degradation. This study attempts to evaluate, by non-destructive sampling, the current status ofP. nobilispopulations in the south Aegean Sea (Dodecanese island complex), where they have been affected for centuries by practically uncontrolled harvesting. Population density and total length of individuals was estimated by diving along strip transects at six islands. Two stations were randomly selected per island, and two depth zones were surveyed per station. Additionally, temporal sampling was carried out at Astypalaia Island from March 2004 to June 2006, to assess relevant trends in density of individuals and size structure of the population. In total 1372P. nobilisindividuals were measuredin situto estimate maximum shell length. The studied populations showed increased density in the shallower depth zone and sheltered sites; small-scale environmental regimes are proposed as shaping factors ofP. nobilisdistribution. Increased density was also detected during the cold period of the year, probably related to recruitment success. In the lower depth zone theP. nobilispopulation consisted of larger individuals. A significant decrease in size was detected temporally as mean length was smaller in December 2004; in the same month the presence of small-sized juveniles was depicted in a left-shift in size–frequency distribution. These observations are probably related to the reproductive biology of the species.

Evaluation of Some Mulberry Varieties for Rearing Performance and Economic Traits of Silkworm (Bombyx Mori L)

The studies on Disease free eggs of silkworm hybrids MY 1 x CSR 2 were utilized. The treatments were V-1, Kanva-2, BER-1, BER-779, Mizosava, A-1, S-30, S-34, S-36, and S-54. Observations on the different economic traits of silkworm Bombyx mori L. were taken. Larval weight varied in the range of 33.77 g to 40.67 g. Variety V-1 (40.67 g), Larval duration was observed in the range of 21.04 days to 22.28 days. Variety BER-1 (21.04 days), Single cocoon weight 1.664 g to 1.863 g. The highest single cocoon weight was V-1 (1.863 g), Single shell weight 0.297 g to 0.364 g. Maximum shell weight V-1 (0.364 g), Shell percentage 17.60 per cent to 19.82 per cent. Maximum yield variety V-1 (18.63 kg), was observed significantly superior, Cocoon filament length in the range of 680.00 m to 836.66 m. Longest filament length variety V-1 (836.66 m). These findings will help the sericulturists in finding suitable variety for getting more economic returns from silkworm rearing. It is observed that V-1 is becoming popular in Marathwada region.

Finite element analysis of filament-wound composite pressure vessel under internal pressure

In this study, finite element analysis (FEA) of composite overwrapped pressure vessel (COPV), using commercial software ABAQUS 6.12 was performed. The study deals with the simulation of aluminum pressure vessel overwrapping by Carbon/Epoxy fiber reinforced polymer (CFRP). Finite element method (FEM) was utilized to investigate the effects of winding angle on filament-wound pressure vessel. Burst pressure, maximum shell displacement and the optimum winding angle of the composite vessel under pure internal pressure were determined. The Laminae were oriented asymmetrically for [00,00]s, [150,-150]s, [300,-300]s, [450,-450]s, [550,-550]s, [600,-600]s, [750,-750]s, [900,-900]s orientations. An exact elastic solution along with the Tsai-Wu, Tsai-Hill and maximum stress failure criteria were employed for analyzing data. Investigations exposed that the optimum winding angle happens at 550 winding angle. Results were compared with the experimental ones and there was a good agreement between them.

Population structure, growth and production of a recent brachiopod from the Chilean fjord region

AbstractMagellania venosa, the largest recent brachiopod, occurs in clusters and banks in population densities of up to 416 ind m−2 in Comau Fjord, Northern Chilean fjord region. Below 15 m, it co‐occurs with the mytilid Aulacomya atra and it dominates the benthic community below 20 m. To determine the question of why M. venosa is a successful competitor, the in situ growth rate of the brachiopod was studied and its overall growth performance compared with that of other brachiopods and mussels. The growth in length was measured between February 2011 and March 2012 after mechanical tagging and calcein staining. Settlement and juvenile growth were determined from recruitment tiles installed in 2009 and from subsequent photocensus. Growth of M. venosa is best described by the general von Bertalanffy growth function, with a maximum shell length (L∞) of 71.53 mm and a Brody growth constant (K) of 0.336 year−1. The overall growth performance (OGP index = 5.1) is the highest recorded for a rynchonelliform brachiopod and in the range of that for Mytilus chilensis (4.8–5.27), but lower than that of A. atra (5.74). The maximal individual production (PInd) is 0.29 g AFDM ind−1 year−1 at 42 mm shell length and annual production ranges from 1.28 to 89.25 g AFDM year−1 m−2 (1–57% of that of A. atra in the respective fjords). The high shell growth rate of M. venosa, together with its high overall growth performance may explain the locally high population density of this brachiopod in Comau Fjord. However, the production per biomass of the population (‐ratio) is low (0.535) and M. venosa may play only a minor role in the food chain. Settling dynamics indicates that M. venosa is a pioneer species with low juvenile mortality. The coexistence of the brachiopod and bivalve suggests that brachiopod survival is affected by neither the presence of potential brachiopod predators nor that of space competitors (i.e. mytilids).

Evaluating the efficacy of land snail survey techniques in Hawaii: implications for conservation throughout the Pacific

Terrestrial micromolluscs (snails with an adult maximum shell dimension <5 mm) constitute a considerable proportion of the land snail fauna of the Pacific. However, micromolluscs are often underestimated in biological surveys because of size bias. It has been argued that visual searches are preferable on Pacific islands because: (1) size biases are limited based on the understanding that most native Pacific island land snails are very small, and (2) amount of labor is less than other methods such as soil surveys and adequate for inventory purposes (though not for abundance assessments). To test whether visual surveys and soil surveys were accurately recording all taxa, land snail inventories were completed in three forest reserves (5 sampling sites in each) on the island of Oahu, Hawaii. Visual surveys involved 30-min visual search in a 10 m2 site; soil surveys involved sieving leaf litter and topsoil from four 0.3 m2 quadrats and extracting snails with the aid of a microscope. The data indicate a size and microhabitat bias associated with both techniques. Visual surveys consistently collected large arboreal and litter-dwelling species but missed a significant portion of micromolluscs, while soil surveys collected micromolluscs but missed larger snails. Because of such biases, employing both methods is critical for collecting all taxa at a survey location. As such, we recommend that future land snail surveys on Pacific Islands incorporate both survey techniques. Obtaining a complete inventory is critical if we are to understand species distributions and patterns of diversity and make well-informed conservation recommendations.

Environmental factors controlling the distribution patterns and abundance of sclerobionts on the shells of Tridacna maxima from the Egyptian Red Sea coast

The living Tridacna maxima shell provides an example of a good substrate for many colonizing marine organisms (sclerobionts). Many factors affect the colonization choices of these organisms, such as morphology and size of the host shell, water depth (related to light penetration), suspended particulate load, and turbidity, among others. In addition to these factors, contamination plays an important role in the colonization choice along the coast of the Red Sea in Egypt. In the present study, 25 specimens of T. maxima shells of different sizes were collected at different depths from eight sites along the Egyptian Red Sea coast. There are two types of contamination at these sites. The first type results from anthropogenic activities, such as tourism, fishing, landfilling, shipping, renewal of ship operations, shipyards, dredging, and petroleum production; this type is represented by the El-Esh area, Hurghada Harbor, Safaga Harbor, and Quseir Harbor. The second type results from the natural inputs from wadis and is represented by the El-Esh area, Quseir Harbour, and Wadi El-Gemal, while the Abu Galawa Lagoon, the Abu Ghusun, and the Hamata Reefs represent uncontaminated areas (control areas). The present study documents the colonization phenomena on T. maxima shells at all of the study sites. These phenomena differed from one another in the abundance and diversity of sclerobionts, and unexpectedly, the contaminated areas recorded the highest abundance and diversity of colonizing organisms.

Late Pleistocene–Holocene environmental conditions in Lanzarote (Canary Islands) inferred from calcitic and aragonitic land snail shells and bird bones

Aragonitic and calcitic land snails from carbonate-rich paleosols in northwestern Lanzarote (Canary Islands) were analyzed for 13C/12C and 18O/16O ratios to deduce the Pleistocene–Holocene transition in the westernmost Sahara zone. Modern, mid-late Holocene (~2.1–5.5calka BP) and late Pleistocene (~23.3–24.0calka BP) aragonitic shells exhibited respective values of −9.5±1.6‰, −7.7±1.5‰, and −2.3±2.8‰ for δ13C; and +0.3±0.3‰, +0.1±0.7‰, and +2.5±0.4‰ for δ18O. Holocene and Pleistocene calcitic shells of the endemic slug Cryptella canariensis showed respective values of −0.7±2.6‰ and −8.5±2.5‰ for δ13C; and +0.8±1.5 and +3.6±0.4‰ for δ18O. Both aragonitic and calcitic shells showed equivalent temporal isotopic trends. Higher δ13C values during ~23.3–24.0calka BP suggest higher abundance of C4 and/or CAM plants, likely associated with drier conditions and/or lower atmospheric CO2 concentration. Maximum shell δ18O values during ~23.3–24.0calka BP opposes minimal values of Greenland ice cores and probably reflect the combined effects of (1) higher rain δ18O values linked to higher glacial seawater δ18O values and/or larger snail activity during summer seasons; (2) relative humidity values similar or slightly lower than at present; (3) higher evaporation rates; and (4) cooler temperatures. Bone remains of the extinct Dune Shearwater Puffinus holeae were only recovered from the Holocene bed. Collagen δ13C and δ15N values (−13.5±0.2‰[PDB] and +13.7±1.0‰[air], respectively) match with the signature of a low trophic level Macaronesian seabird that fed upon local fish. Bone carbonate δ13C (−7.4±1.0‰[PDB]) and phosphate δ18O (+18.2±0.4‰[SMOW]) values exhibited pristine signals denoting their potential value in future paleoenvironmental studies in the region. The age of P. holeae (~2.1–2.7calka BP) supports that the aboriginal population possibly caused its extinction. In contrast, the extinction of the endemic helicid Theba sp. (~23.3–24.0calka BP) was likely caused by environmental change.

Modelling the effects of recreational boating on self-purification activity provided by bivalve mollusks in a lowland river

Self-purification is a key ecosystem service provided by riverine biota that is particularly important in polluted water bodies serving multiple societal uses, but the extent to which self-purification may be influenced by human uses is unknown. We studied a eutrophic lowland river used for drinking water and recreation to identify the maximal sustainable extent of human use. We recorded filtration by mussels and modeled the disturbance to mussels caused by wave action induced from recreational boating. Filtration was significantly affected by shear stress produced from boats down to a depth of 2.7 m. Threshold values for the intensity of wave disturbance ranged from 0.21 N/m2 (Unio tumidus) to 0.43 N/m2 (Anodonta anatina) for moderate effects and from 0.02 N/m2 (U. tumidus) to 0.13 N/m2 (Dreissena polymorpha) for no effects on filtration. Anodonta anatina and D. polymorpha showed a significantly lower degree of shell closing and a higher predicted medium-effect shear stress (the shear stress associated with 50% of the maximum shell closing duration) than U. tumidus and Unio pictorum, which probably results from differences in the species position in and above the sediment. Coupled hydraulic–ecological modeling showed that typical boating activity may reduce self-purification activity by mussels, with the extent of disturbance depending on mussel species, river depth, boating frequency, and cruising speed. Single passages of boats reduced daily mussel filtration rates by 0.02% for muscle-driven boats, 0.45% for yachts, 0.68% for motor boats, and 0.69% for motorized rafting and rowing boats. Depending on total daily boat traffic and hydrological conditions, a reduction in the daily filtration rate by mussel populations within the studied river section was estimated at 6.9%. We conclude that self-purification activity of this lowland river section is not significantly affected by recreational boating, but might be affected by more intense recreational boating under altered river flow conditions.

Facile Synthesis of Monodispersed In2O3 Hollow Spheres and Application in Photocatalysis and Gas Sensing

Monodispersed, agglomerate‐free In2O3 hollow spheres have been prepared via a simple synthetic route involving permeation and anchoring of In3+ ions with carbonyl groups of swollen commercial polymer beads in tetrachloroethylene solvent followed by thermal removal of the template cores in ambient air. The as‐synthesized hollow spheres exhibit a narrow size distribution with tunable particle size (0.5–1.2 μm) and shell thickness (62–230 nm) over the process variables examined, i.e., InCl3 precursor concentration (4.5 × 10−3–6.7 × 10−2 M), reaction temperature (55°C–95°C), and reaction time (1–6 h). Kinetics calculation reveals that the formation of permeating In3+‐rich shell in the swollen template beads becomes energetically less favorable to proceed as the reaction time increases. This limits the maximum shell thickness attainable at the given process variables. The shell is nanoporous with a Horvath‐Kawazoe (HK) pore size of ~3 nm, which remains essentially unchanged as the process variables alter. The In2O3 hollow spheres with an increased Brunauer‐Emmett‐Teller (BET) surface area (up to 329 m2/g) show an improved capability in photodegradation of aqueous methylene blue (MB) dye under UV exposure as well as an increased sensitivity for CO‐gas detection. This metal‐implantation scheme is general and can be extended to the synthesis of other hollow materials in various solvent liquids.

Effects of Suspended Sediments on Seston Food Quality for Zebra Mussels in Lake Markermeer, The Netherlands

Until 1992, zebra mussels (Dreissena polymorpha) were an important food source for diving ducks in Lake Markermeer (The Netherlands). After 1993, the mussel biomass sharply declined, and the current population is in poor condition (maximum shell length <15 mm) compared to populations from adjacent Lake IJsselmeer. Lake Markermeer is characterized by high concentrations of total suspended matter (TSM), including 70% inorganic suspended sediments (ISS) affected by wind-driven resuspension, which may influence the food uptake by the mussels. We assessed whether the poor condition of the zebra mussels in Lake Markermeer could be attributed to the high TSM concentrations, and especially the fraction of ISS. In situ measurements of near-bottom TSM concentrations were linked to wind-driven wave action, and experiments were carried out using increasing natural sediment (NS) concentrations combined with a fixed concentration of a green alga (Scenedesmus obliquus) to determine the clearance rates (CR) of adult and juvenile zebra mussels. CR on NS particles decreased with increasing NS concentrations. The CR on S. obliquus, however, increased with an increasing NS concentration up to 0.75 g L−1 for adult mussels, indicating that zebra mussels can tolerate relatively high TSM concentrations and selectively graze on phytoplankton. Zebra mussels eventually reduce their CR at high TSM concentrations; the CR of juvenile mussels on S. obliquus collapsed at NS concentrations >0.5 g L−1. The NS concentrations used in this study are high, but analyses of the near-bottom TSM concentrations show that these values occur frequently and may be partly responsible for the poor mussel status in Lake Markermeer.

Crecimiento del mejillón verde &lt;i&gt;Perna viridis&lt;/i&gt; (Bivalvia: Mytilidae) bajo sistema de cultivo de fondo en la ensenada de Turpialito, Golfo de Cariaco, Venezuela

Mussels represent one of the most important mollusk species for culture activities around the world, and their growth may depend on the culture system used and locality. In this study, we evaluated the growth of Perna viridis in bottom culture to test its performance when using natural food, and to decide its use as a culture species in the Gulf of Cariaco. For this, mussel seeds (35.81 +/- 1.41 mm in length) were obtained in the locality of Guaca (North coast of Sucre state) and transferred to the Hydrobiological Station of Turpialito, Gulf of Cariaco, Sucre state, Venezuela, where they were planted in "Spanish baskets" to evaluate their growth between July 2007 and February 2008. Monthly survival was determined and the maximum shell length, dry mass of muscle and remains tissues of the gonad. The environmental parameters (water temperature, salinity, dissolved oxygen, chlorophyll a, total seston and organic fraction), in the cultivation area were determined every 15 days. Monthly measurements were made of proteins, lipids and carbohydrates to seston. During the entire study the mussels showed continued growth, ultimately reaching a maximum length of 78.7 +/- 4.43 mm. However, the growth rate of the dry mass of somatic (muscle, other tissue) and reproductive tissues showed variability throughout the study, and observed a significant increase by the end of the experiment. The observed variations in the growth rate of the reproductive tissue mass depended on the reserves accumulated and food offered by the environment. The organic seston throughout the experience showed an independence of temperature and chlorophyll a values; this one maintained values above 1 mg/L, thus forming the main food resource for mussels. The high content of proteins, lipids and carbohydrates observed in the seston at the end of the study, might be mainly associated with coastal upwelling, which provides a great food contribution of phytoplankton and organic type. The high survival rate (>80%), increase in the length of the shell and the high gonad production, suggests an excellent physiological condition of P. viridis, related to the availability and quality of food particularly the organic type present in the medium. We concluded that the bottom culture can provide an alternative aquaculture production in the Gulf of Cariaco.

Description of a new species of Calliostoma (Gastropoda, Calliostomatidae) from Southeastern Brazil

Calliostoma tupinamba isa new species from Southeastern Brazil, ranging from southern Rio de Janeiro to northern São Paulo, and found only on coastal islands, on rocks and sessile invertebrates at 3 to 5 meters of depth. Shell and soft part morphology is described here in detail. Calliostoma tupinamba is mainly characterized by a depressed trochoid shell; eight slightly convex whorls; a sharply suprasutural carina starting on the third whorl and forming a peripheral rounded keel; and a whitish, funnel-shaped and deep umbilicus, measuring about 5%–10% of maximum shell width. Calliostoma tupinamba resembles Calliostoma bullisi Clench & Turner, 1960 in shape, but differs from it in being taller and wider, having a smaller umbilicus and lacking a strong and large innermost spiral cord at its base. Finally, an identification key of Brazilian Calliostoma species is presented.

Acetabular Cup Design Influences Deformational Response in Total Hip Arthroplasty

Press-fit acetabular components are susceptible to deformation in an underreamed socket, with excessive deformation of metal-on-metal (MOM) components potentially leading to increased torsional friction and micromotion. Specifically, however, it remains unclear how cup diameter, design, and time from implantation affect shell deformation. We asked whether (1) changes in component geometry and material altered maximum shell deformation and (2) time-dependent deformational relaxation processes occurred. Diametral deformation was quantified after press-fit implantation of metal shells into a previously validated polyurethane model. Experimental groups (n=6-8) consisted of 48-, 54-, 60-, and 66-mm MOM cups of 6-mm wall thickness, 58-mm cups of 10-mm wall thickness, and CoCrMo and Ti6Al4V 58-mm modular cups. Greater cup diameter, thinner wall construction, and Ti6Al4V modular designs generated conditions for maximum shell deformation ranging from 0.047 to 0.267mm. Relaxation (18%-32%) was observed 120 hours postimplantation in thin-walled and modular designs. Our findings demonstrate a reduction of shell deformation over time and suggest, under physiologic loading, early component deformation varies with design. Component deformation should be a design consideration regardless of bearing surface. Designs neglecting to adequately address deformational changes in vivo could be susceptible to diminished cup survival, increased wear, and premature revision.

Maturation and age in queen conch (Strombus gigas): Urgent need for changes in harvest criteria

The queen conch (Strombus gigas) is a large economically important gastropod that has been severely depleted throughout much of the Caribbean region. The species has determinate growth and reaches maximum shell length before sexual maturation; thereafter the shell grows only in thickness. In this study, queen conch were collected in the Exuma Cays, Bahamas, to evaluate maturity with respect to shell length (SL) (170–255mm) and shell lip thickness (LT) (2–42mm). Soft tissue weight and gonad weight increased with SL, but these same variables, along with the gonadosomatic index (gonad weight/soft tissue weight), all had dome-shaped distributions with LT and decreased slightly with LT>22mm. This indicates some loss of fecundity with age; however, no loss of reproductive capability was evident in histological data. Gonad maturity lagged substantially behind first formation of the shell lip. Minimum LT for reproductive maturity was 12mm for females and 9mm for males, and 50% maturity for the population was achieved at 26mm LT for females and 24mm LT for males, higher than previous estimates. A review of fishing regulations indicates that immature queen conch are being harvested legally in most Caribbean nations, providing at least a partial explanation for widespread depletion. While relationships between shell lip thickness, age, and maturity vary geographically, sustainable management of queen conch will require a minimum shell lip thickness for harvest no less than 15mm, along with other urgently needed management measures.

The distribution, size and age compositions, and growth of the scallop Mizuhopecten yessoensis (Bivalvia: Pectinidae) in the northwestern Tatar Strait

The distribution patterns, size, age structure, and growth of the scallop Mizuhopecten yessoensis were studied in the northwest of the Tatar Strait, Sea of Japan. We determined that the northern boundary of the species range occurred in the region of Tabo Bay, at 51°37′ N. The distribution of the mollusk, depending on latitude, depth, substrate, and age, was determined. The maximum depth of M. yessoensis habitat is 138 meters, the maximum shell height is 200 mm, and the maximum age is 14 years. The differences in the growth rate of the Japanese scallop in different areas are discussed in relation to the conditions of its habitat in the northern part of its range.

The Effects of Sex and Season on Patterns of Thermoregulation in Blanding's Turtles (Emydoidea blandingii) in Ontario, Canada

When preparing management plans for species at risk, conservation practitioners need information on the habitat requirements of those species. In environmental extremes, the fitness of ectotherms is tightly linked to thermoregulation, as all physiological processes are temperature dependent. In an effort to better quantify the habitat requirements of Blanding's turtles (Emydoidea blandingii), a species at risk, at the northern extreme of their range, we quantified the thermoregulation patterns of adult males and gravid females during the active season. Turtles exploited their thermal environment significantly more in early season than in late season. Although basking allowed turtles to reach the highest daytime temperatures, surface water was the habitat with the highest thermal quality overall. Although not statistically significant, gravid females tended to maintain higher mean and maximum shell temperatures throughout the active season. Gravid females also spent substantially more time basking than males throughout the active season. Our results highlight the importance of stratifying field observations and thermoregulation data by reproductive class and time. Differences in behavior and thermal habitat requirements between reproductive classes and season must be considered in management plans for conservation efforts to be effective.