Relative Growth Relationship between Different Body Parts of the Bivalve Gari virescens and its Shell Length — Allometric Formulas for Shell Length Size Reconstruction

Mass production method on artificial seedling production of hard clam Meretrix petechialis was developed indoor culture system. Spawning of adult clam (SL 65.8 ± 8.4 mm) was induced using the combined method of air exposure and water temperature raising. The fertilized eggs were developed to D-shaped larvae after 17.7 hours at 27℃ and hatching rate was 6.1%. Shell length (SL) of D-shaped larvae was measured to be 131.4 ± 2.6 μm and thereafter the larvae grew to the settled spats with SL 190.2 ± 7.5 μm in 4 days. Estimated survival rate of settled spats was 48.1%. Spat collection on 130,000 spats with SL 0.19 ± 0.01 mm performed conducted by sand bottom circulation filtering method. Collected spats grew up to 3.1 ± 0.8 mm in 46 days, 6.6 ± 1.8 mm in 87 days, and 10.5 ± 0.9 mm in 114 days. The relative growth between SL and shell height (SH) was calculated to be SH = 0.8501SL + 0.0196 (R 2 = 0.9987) during the whole spat period. During spats rearing, they were suffered from one time of mass mortality at SL 3.1 mm, but 51,000 spats were finally survived with the rate of 39.2% at 114 days of spat rearing in indoor tank system.

Growth of the smooth clam, Callista chione (Linnaeus, 1758) (Bivalvia: Veneridae) from the Thracian Sea, northeastern Mediterranean

The present study reports and discusses population structure and morphometric relationships of muricid <em>Reishia bitubercularis</em> in two populations from Ambon Island, Maluku. Field sampling was conducted at two locations with typical hard substrate i.e. Ambon Bay and Central Maluku, where each location comprises three different stations. Morphometric relationships were analyzed for shell dimensions i.e., shell length (SL), shell width (SW), shell height (SH) and total weight (TW). A total of 496 individuals of <em>R. bitubercularis </em>were collected in both locations. SL ranged from 7.07 to 42.38 mm in Ambon Bay, and 12.45 to 42.69 mm in Central Maluku. The highest number of individuals in Ambon Bay and Central Maluku was in size 26-28 mm and 30-32 mm, respectively. The mean SW/SL ratio ranged from 0.67 mm to 0.73 mm. Sex ratio was significantly different from 1:1, with females outnumbered males in both locations. Morphometric relationships indicated SL grows faster than SW in both locations and faster than SH and TW in Central Maluku. While the growth rate between SL vs SH; and TW vs SL are relatively similar in Ambon Bay. Overall, both Ambon Bay and Central Maluku have a similar variation of abiotic factors which also play an important role in shell morphometrics and relative growth of muricids, especially related to the exposed area in the rocky intertidal zone where sampling was conducted.

Nitrite is a common pollutant in marine environments and can cause mortality in crustaceans and bivalves. The purpose of the current study is to understand nitrate’s toxicity to juvenile clams due to its potential impact on aquaculture and marine ecosystems. Juvenile sunray surf clams (Mactra chinensis Philippi) (1.00 ± 0.10 cm shell length, 0.75 ± 0.04 cm shell height) were exposed to varying concentrations of nitrite for 96 h and 20 days, respectively. The LC50 for survival at 96 h was 37 mg/L NO2-N. Histological evaluations were made on juvenile clams exposed at 30 mg/L after 20 d of exposure. Epithelial cells and digestive diverticulum are the best sub-lethal effect indicators. Shell length and antioxidant enzyme activities were measured at the beginning of the experiment and then observed 10 and 20 days after exposure. A logarithmic relationship was obtained between the relative growth rate (based on the shell length) of juvenile M. chinensis and the nitrite concentration. Compared to the control, activity suppression of superoxide dismutase and catalase activity was detected from the concentration of 1 mg/L NO2-N. It is recommended that nitrite concentrations remain below 1 mg/L to prevent stress during the early developmental stages of clams.

Spatiotemporal distribution and growth pattern of Venus nux (Gmelin, 1791) in the Gulf of Cádiz (Southern Spain)

Effects of three light intensities on the survival, growth performance and biochemical composition of two size giant clams Tridacna crocea in the Southern China Sea

The present study reports morphometric relationships and discusses the relative growth in the banded murex (Hexaplex trunculus) and the purple dye murex (Bolinus brandaris) from the Ria Formosa lagoon (southern Portugal). A total of 11 morphometric parameters (eight linear variables: shell length, shell width, total aperture length, aperture length, aperture width, spire length, spire width and siphonal canal length; three ponderal variables: total weight, soft parts weight and shell weight) were analysed in both species. The analyses comprised numerous individuals of both sexes and with broad size ranges (H. trunculus: 10.7–82.8 mm shell length;B. brandaris: 14.6–107.7 mm shell length), fairly representative of the populations from the Ria Formosa lagoon. In general,B. brandarisexhibited greater morphological plasticity and higher variability in shell shape compared withH. trunculus. In both species, the vast majority of morphometric relationships displayed positive allometries, distantly followed by negative allometries and by isometries. AlthoughH. trunculusandB. brandarisare known to lack external sexual dimorphism, several morphometric relationships revealed significant differences in the type of growth between sexes, which should be further confirmed using more powerful techniques, such as geometric morphometric analyses of shell shape.

This study reports the morphometric relationships and relative growth of 20 uncommon bivalve species collected along the Algarve coast (southern Portugal). Morphometric relationships were established between three linear variables (shell length, height and width) and one ponderal variable (total weight) and the relative growth between variables (isometryvsallometry) was analysed in order to assess their variation throughout ontogeny. In addition, morphometric indices (elongation, compactness, convexity and density) based on ratios of those linear and ponderal variables were calculated in order to further characterize morphologically the bivalve species. A total of 2512 individuals belonging to nine bivalve families were analysed, comprising specimens with broad ranges in both shell length (11.8–109.0 mm SL) and total weight (0.2–354.6 g TW). All morphometric relationships were highly significant (P< 0.001) and displayed invariably high correlation coefficients (r= 0.727–0.998). Among a total of 60 morphometric relationships, 27 isometries, 25 positive allometries and 8 negative allometries were registered. The morphometric indices displayed a remarkable variation among taxa, reflecting the high morphological diversity of these miscellaneous bivalve species. Discriminant analysis provided a spatial visualization of the species morphometric variables that further evidenced their main shape features, the distinctness between some species and families (e.g. Pharidae and Cardiidae) and the morphological resemblance among some species belonging to other families (e.g. Veneridae and Tellinidae). Overall, this information is useful and has practical application in diverse research fields, including studies on systematics and taxonomy, physiology, biology, ecology, fisheries assessment and management.

Evaluating whether velar lobe size indicates food limitation among larvae of the marine gastropod Crepidula fornicata.

The optimal tide height at which the intertidal oyster bed system (IOBS) should be installed to cultivate Crassostrea corteziensis in Boca de Camichín (BC), Nayarit, Mexico, during the intermediate grow-out stage (39.3–60.2 mm in shell length) was determined. Temperature, salinity, chlorophyll a (Chla), and turbidity were recorded 3 times a day. A trophic state index (TSI) was calculated with Chla and turbidity data. Three treatments corresponding to tide levels were tested: (1) high level (14 cm above mean sea level [MSL], emersion time [ET] = 56.4% of the total duration of the experiment), (2) intermediate level (MSL, ET = 48.6%), and (3) low level (41 cm below MSL, ET = 32.1%). Gross growth rates and absolute and relative monthly growth rates were calculated to identify periods with highest growth relative to environmental conditions. Finally, the effect of the treatments on the dimensions and weight of the oysters was studied. The results indicate that BC water was mesotrophic in April–June and eutrophic in July–August. The low tide level was the best for IOBS operation, with growth rates of 0.15, 0.10, and 0.07 mm·d–1 in shell length, width, and thickness, respectively, and 0.204 g·d–1 wet weight. Cumulative mortality was lower in the low (18.5%) and intermediate (16.4%) treatments. Shell thickness was significant reduced (P < 0.05) in the high treatment and total wet weight was reduced in the high and intermediate treatments. The results of this study offer a viable and different alternative to the cultivation of C. corteziensis in strings that is currently carried out in Boca de Camichín, Nayarit, Mexico.

속성장을 위한 선발 1세대 전복 (Selected abalone : SA)의 성장률을 조사하기 위하여 동일 사육 환경 조건에서 대조구 전복 (Control abalone : CA) 과 비교실험을 하였다. 그 결과 각 성장형질 (각장, 각폭 및 중량) 은 SA구가 CA구보다 유의하게 빠른 것으로 나타났다. 45일째 및 90일째의 평균 각장에 있어 SA구가 CA구 보다 각각 31.7% 및 17.8% 빠르게 나타났으며, 중량에 있어서도 각각 43.7% 및 25.6% 빠른 것으로 나타났다. 더욱이 90일째의 각장과 중량의 상대성장 비교에 있어서도 SA구가 CA구 보다 유의적으로 높은 상관관계를 나타내었다. 이러한 결과는 선발육종기술을 이용하여 양식 전복의 성장률을 증대할 수 있는 가능성을 시사하고 있다. The growth rates of offspring of selected abalone (SA), Haliotis discus hannai, population for rapid growth were compared to those of offsping of the control abalone (CA) at bred under the same condition. The growth traits (shell length, shell breadth and total weight) of SA were significantly faster than those of CA at this experiment. At the 45th day and 90th day, the growth rates in shell length of SA were estimated 31.7% and 17.8% faster than those of CA, total weight of SA were estimated 43.7% and 25.6%, respectively. Moreover, the relative growth rate between shell length and total weight of SA showed significant differences higher than one in CA at 90th day. The results suggest a possibility of improving the growth rate of cultured abalone using selection techniques.

The present study reports weight-length (W-L) relationships and discusses the relative growth of the banded murex (Hexaplex trunculus) from intertidal and offshore areas of the Gulf of Gabes (southern Tunisia). Overall, 9634 H. trunculus were sampled (6608 from intertidal and 3026 from offshore), with both populations comprising broad ranges in shell length (intertidal: 13.6–78.5 mm; offshore: 22.9–91.1 mm) and total weight (intertidal: 0.2–63.8 g; offshore: 0.6–92.5 g). In both populations, W-L relationships were highly significant and the morphometric parameters were highly correlated (intertidal: r = 0.967; offshore: r = 0.973). Relative growth was significantly different between populations, with intertidal H. trunculus displaying a negative allometry (b = 2.962) and offshore H. trunculus exhibiting isometric growth (b = 3.013). Factors influencing total weight (soft-body weight and shell weight) and potentially responsible for differences in W-L relationships and relative growth between populations were discussed. In addition, a useful comparative analysis for fisheries biology, assessment and management purposes was performed with analogous information from other populations of H. trunculus from the Mediterranean Sea and the Atlantic Ocean.

This study analysed and compared the shell shape, morphometrics and relative growth of four sympatric limpet species (Patella depressa,Patella ulyssiponensis,Patella vulgataandSiphonaria pectinata) collected at Praia da Luz in Lagos (Algarve coast – southern Portugal). Morphometric relationships were established through regression analysis between linear (shell length, width and height), ponderal (total weight), area (shell base and surface areas) and volume variables (shell internal and total volumes). Relative growth (isometryvsallometry) was analysed to assess variation in the growth rate of morphometric variables throughout the species ontogeny. In addition, morphometric indices (ellipticity, conicity, density, surface area and volumetry) were calculated to further characterize shell shape. Overall, 1482 individuals with broad size and weight ranges were analysed (P. depressa= 354;P. ulyssiponensis= 306;P. vulgata= 408;S. pectinata= 414). All regressions were highly significant (P< 0.001) and the morphometric variables were strongly correlated (r= 0.761 to 0.994). Among 28 morphometric relationships, there were 14 isometries, 13 positive allometries and only one negative allometry. The morphometric indices revealed clear morphological differences between species and were mostly size-dependent, reflecting gradual changes in shell shape during growth. The main results are compared with a compilation of analogous data reported for these limpet species throughout their distributional range. Overall, the general trends in relative growth are discussed in terms of the species life habits, main traits and functional morphology.

Relative growth and the reproductive cycle of the date mussel Lithophaga lithophaga were studied from September 2002 to October 2003 in the Bizerte Bay (Northern Tunisia). Relationships between shell length and shell width, shell height as well as volume-related variables (shell dry weight, soft tissues dry weight and total wet weight) showed negative allometries in both sexes except for shell width in males (isometry) and shell height in both sexes (positive allometry). The sex ratio was unbalanced, within the length range of 6–48 mm, 49.43 % of the animals were males, 24.39 % females and 26.17 % sexually undifferentiated; within the length range of 49–92 mm, the respective values were 41.19, 52.7 and 6.1 %. Histological investigations as well as analyses of the condition index and the gonadosomatic index (CI and GSI) revealed the presence of a single reproductive cycle per year. Spawning occurred at the end of August and early September and was associated with a decrease in seawater temperature and salinity. A resting phase occurred in winter, coinciding with the lowest water temperatures. Histological examinations of the gonads of a total of 130 specimens revealed only two cases of hermaphroditism. The present study constitutes a useful baseline for a sustainable management of local wild stocks of L. lithophaga.

The Indian rock oysters, Crassostrea cattuckensis (80-90 mm shell length) were exposed to sub lethal levels of zinc for 15 days and 30 days for metal accumulation and next 15 days for metal depuration. The oysters, which served as experimental control after 15 days showed high amount of lipid (mg/100 mg) in hepatopancreas ( 3.32) followed by gills (3.20), mantle (3.08), gonad (2.90), adductor muscle (2.78) and siphon (2.11). During 15 days metal exposed oysters to (0.65) and (0.94) ppm concentrations there was changes observed in different body parts when compared to experimental control. The decreased rate upon 15 days in (0.65 ppm) concentrations was in mantle (2.96), than gill (2.22), hepatopancreas (1.72), gonad (1.59), siphon (1.51) and adductor muscle (1.50). While in (0.94 ppm) the protein was decreased in adductor muscle (2.51), gonad (1.61), siphon (1.44), gill (1.42) and it increased in mantle (3.90) and hepatopancreas (3.34) when it was compared to experimental control. Whereas upon 30 days exposure the lipid content increased among body parts in both concentration except the gills (1.35), gonads (1.97) and hepatopancreas (1.66) in higher concentration when compared with experimental control. The lipid increased in (0.65 ppm) from gonad (2.29), hepatopancreas (2.25), adductor muscle (2.22), gills (2.20), mantle (2.14) and siphon (1.44). While in (0.94 ppm) lipid increase trend was from mantle (4.27), adductor muscle (2.46) and siphon (1.42) and decreased from gonad (1.97), hepatopancreas (1.66) and gills (1.35) when compared with 30 days experimental control. During detoxification process the lipid content was increased in both concentrations except gill (2.11) in low and adductor muscle (0.99), siphon (0.74) in high concentrations when compared with respective concentrations of 15 days exposed oysters. The increase rate in low concentration was from mantle (4.32) than from adductor muscles (4.12), gonad (3.60), hepatopancreas (2.46) and siphon (1.05). In high concentration it was more in hepatopancreas (4.93) than gonad (4.42), gills (4.08) and mantle (4.01).