ABSTRACT Size class dependent variations of growth and fecundity of three small land snails, Allopeas gracile (Hutton 1834) (Gastropoda: Subulinidae), Succinea daucina (Pfeiffer, 1855) (Gastropoda: Succineidae) and Glessula gemma (Reeve 1850) (Gastropoda: Subulinidae) were assessed in the laboratory condition. The field collected snails were segregated according to the size (shell length, in mm), and the frequency distribution of each size class was estimated. Subsequently, each size class was reared in the laboratory with continuous monitoring for the deposition of the eggs in the rearing terrarium for a period of six weeks using three replicates per size class. The growth rate of each species was highest in the smallest size class and declined gradually with the increment of shell length. The shell lengths of A. gracile and S. daucina at sexual maturity were 4–5 mm and 6–7 mm, respectively, and fecundity was positively linked with the size (shell length). G. gemma did not oviposit, except that the large size-class had given few small offspring. The results showed that growth and reproduction of three species varied significantly with size classes, which reflects the ability for these snails to colonize and establish in favourable habitats in short time period.

ABSTRACT Protocols for hirudiculture have not been fully established; many issues need to be investigated. The present study aimed to determine the effects of the cocoon incubation angle (CIA) on hatching success in hirudiculture, using leech species of Hirudo verbana. Cocoons were individually incubated in jars at three different angles, horizontally (0°), angled (45°), and vertically (90°) for one month. The rot in cocoons, which was 17.5% in cocoons incubated horizontally, decreased gradually as the CIA increased, was 2.5% in cocoons incubated vertically. The average number of offspring obtained from cocoons increased as the CIA increased. The optimum CIA was determined to be 78.73° and 60.63° for the lowest rot in cocoons and the highest number of offspring, respectively. The present study revealed that although not statistically significant the CIA is a variable affecting the hatching success of medicinal leeches during the incubation period. This result is thought to be because the air ventilation inside the cocoons is more efficient in cocoons positioned at an angle or in a vertical position compared to cocoons incubated in a horizontal position. For profitable hirudiculture, we recommend that cocoons be positioned at an angle close to vertically, more than 60° during incubation.

ABSTRACT We investigate the onset of morphological sexual maturity, sexual dimorphism and relative growth of the freshwater crab Fredius ibiapaba. We collected the specimens bimonthly between August 2017 and June 2018. We measured the crabs to obtain the following morphometric variables: carapace width (CW); pleon width (PLW); propodus length (PL); propodus height (PH) and propodus width (PW). A total of 175 specimens of F. ibiapaba were analysed. The onset of morphological sexual maturity was estimated at 31.7 mm for males, and at 35.2 mm for females. We observed sexual size dimorphism in CL and PLW, with females larger than males. Positive allometry of cheliped variables was observed in juvenile and adult males, while females showed positive allometry of PLW in juvenile and adult. Finally, the growth of the variables was different between adults and juveniles in both sexes. The ecological information obtained in our study is unprecedented for the genus Fredius. The sexual size dimorphism with females larger than males, probably resulting from their reproductive biology. Additionally, the energy expenditure in cheliped growth in males, may be associated with success during agonistic disputes and the use of these structures to position females during copulation, since they are larger in body size.

ABSTRACT We performed a comparative analysis of fecundity and reproductive effort of two hermit crab species, Clibanarius antillensis and Calcinus tibicen, distributed along the two marine provinces in Brazilian coast. Samples of both species were manually collected during spring low tides on a two-month basis, from February 2011 to January 2012 at locations separated by ~ 3000 km: North-eastern (NE) region – Pedra Rachada Beach (Ceará); South-eastern (SE) region – Araçá Beach and Grande Beach (São Paulo). The size of ovigerous females, as well as the fecundity values, egg volume, internal volume of occupied shells, and reproductive effort were analysed, and the results evidenced significantly higher values for females of both species collected in SE localities. In females collected NE, there was also the presence of aberrant eggs, which influenced the reproductive parameters analysed for these species, resulting in lower reproductive effort. Biomass invested in egg production varied between populations, but ovigerous females of SE invested a higher percentage of their weight in the production of its egg mass, showing significant differences in the reproductive effort. Variation in reproductive performance detected for both species may be related to latitudinal location and associated to the habitat’s characteristics.

ABSTRACT Sex steroid hormones occur in the bivalve tissues. Testosterone (T), various oestrogens, and progesterone have been reported in this group of organisms and the amounts of these hormones have been correlated with seasonal variation and reproduction. Yet, neither the role nor the origins of sex steroids are fully clarified. Thus, we tested the hypothesis that, apart from the esterification process, the aromatisation of androgens to oestrogens can help balance T levels during gonadal development in both sexes using Mytilus edulis trossulus as a model species. The highest testosterone concentrations were found in developed male and female gonads (IV reproductive stage of gametogenesis). The highest aromatisation efficiency was also found in the developed male and female gonads, but also in the gills. During the other stages of gametogenesis (II, III, V-I), a decrease in both testosterone concentration and aromatisation efficiency was observed in the gonads of males and females, as well as in the gills of males. However, the decrease in testosterone concentration did not affect the 17β-oestradiol concentration in mussel tissues. Thus, together with the esterification process, the ongoing aromatisation in bivalve tissues may help keeping balanced T levels.

ABSTRACT The present study determined the effect of different polychaete extracts, namely, total soluble fraction (TSF), neutral lipid fraction (NLF) and polar lipid fraction (PLF), in the maturation and sperm quality of male Penaeus indicus. Three levels (0.25, 0.50 and 1.00%) of extracts were included using a 3 × 3 factorial design. Groups fed the basal diet (BD) and fresh-frozen diet served as controls. Extracts in varying doses and control groups did not have a significant effect on broodstock survival (67–87%; p = 0.960), maturation rate (42–68%; p = 0.615), inter-spermatophore period (8–10 days; p = 0.505) or sperm viability (97–100%; p = 0.819). However, sperm counts of broodstock fed BD (11.70 × 106 ±1.05 × 106 per spermatophore) and those fed diets supplemented with polychaete extracts were significantly higher compared to that fed with control fresh diet at 0.73 × 106± .09 × 106 (p = 0.001). Spermatophore crude lipid was highest in groups fed 0.25% TSF and 0.25% PLF of broodstock (p =1.0 x10−6 ). Inclusion of TSF (0.25–1.00%) significantly increased the spermatophore crude protein content of broodstock compared to those fed with other diets (p = 1.20 × 10−5). These results demonstrate that NLF and TSF extracts are bioactive components of polychaete which when fed to male P. indicus, can stimulate aspects of sperm production.

ABSTRACT The leech Whitmania pigra is well known in traditional Chinese medicine for promoting human blood circulation and alleviating blood stasis. To evaluate its suitability as bait for this neonate leech, we investigate the reproductive efficiency of the snail Radix plicatula under laboratory conditions. Furthermore, the effects of the size of R. plicatula on the growth of newborn W. pigra were evaluated. Wild snails laid eggs in mid-March with body weight >0.223 g and peaked at the beginning of April to early May. The accumulated number of eggs was 1489.70 ± 895.98 and 2145.67 ± 694.47 separately for individual and paired snails (P = 0.083). The time elapsed up to the hatching of the first egg in the four collected egg masses ranged from 12 to 18 days, and the hatching percentage ranged from 97-% to 100-%  . The predation rate of the newborn W. pigra was significantly higher when feeding on small snails than on medium and large snails (P < 0.01). Furthermore, increased snail size resulted in decreased leech growth and survival rates. The investigations demonstrated that the snail R. plicatula could serve as a suitable living bait in the rearing of W. pigra to help alleviate the scarcity of leech on the market.

ABSTRACT We investigated the relative growth and sexual maturity (gonadal and morphometric) of Libinia spinosa. Crabs were sampled at Ubatuba from January to December 2000, using trawls. Based on allometric growth, males were grouped into juveniles (MJ), adolescents (MAd) and adults (MA) based on the relationship CPL (major cheliped propod length) vs. CW (cephalothorax width), all with positive allometric growth. For females, the relationship AW (abdomen width) vs. CW allowed segregating juveniles (FJ) from adults (FA), with positive allometric growth for FJ but isometric growth for FA. The morphometric maturity evidenced for MAd varied from 33.7 mm to 34.5 mm and for MA and FA. The size at which 50% of individuals reach the morphometric sexual maturity was L50 = 50.1 mm for males and L50 = 37.3 mm for females. Gonad maturity was L50 = 33.7 mm for males and L50 = 36.9 mm for females. Through relative growth analyses, we identified an adolescent male group (prepuberal phase). These individuals presented mature gonads, enabling them to copulate with females. These adolescent males may reproduce while avoiding competition with adult males, as it happens in other species of Majoidea that present more than two morphotypes in the population.

ABSTRACT The main Spondylus limbatus population parameters were estimated based on the analysis of individual growth and reproductive aspects of specimens collected monthly (n = 30) from January to December 2009 in the fishing area of Agua Verde, Gulf of California. The size structure determined from shell measurements was 82–167 mm and the direct reading of shell sections indicated ages of 1–14 years. The data were adjusted to the von Bertalanffy, Gompertz, logistic, Richards and Schnute (Type 1) growth models. The von Bertalanffy model provided the best fit to describe individual growth in this species (SH∞  = 142.7 mm, k = 0.47, t0 = −0.20 years). The spawning season was determined through gonadal histology, and the size and age at sexual maturity through a logistic model. Reproductive activity occurred from March to September, with spawning peaks in July and August. The size and age at sexual maturity were 10.8 mm and 2.7 years, respectively. This information provides the necessary knowledge to implement management measures in the area. We recommend independent studies to establish management measures for each fishing area.

ABSTRACT The giant freshwater prawn (Macrobrachium rosenbergii), which is widely distributed in Southeast Asia and the western Pacific, is an important commercial prawn species. However, the molecular mechanism of ovarian development is unclear, and available data on the ovarian transcriptome of M. rosenbergii are limited. In this study, we constructed transcriptomes of female (ZW) and super female (WW) of M. rosenbergii ovaries to discover genes and pathways related to ovarian development. A total of 71,555 unigenes were obtained, with an average length of 1,530 bp and N50 of 3001 bp, and 15,792 (29.3%) of them were annotated. A total of 13,610 differentially expressed genes (DEGs) were detected. KEGG pathway analysis showed that multiple pathways related to ovarian development were significantly regulated, such as retinol metabolism, notch signalling pathway, cell cycle, wnt signalling pathway, FoxO signalling pathway, and mTOR signalling pathway. In addition, 12 putative ovarian development-related genes, including FZD9, DDR2, PSMC3IP, CREBBP, DMC1, WBP2NL, DHRS4, SPO11, BCDO2, SDR16C5, CPEB, RDH5, were identified. Our findings will provide a valuable archive for future functional analysis of genes related to ovarian development and future discoveries of the underlying molecular mechanisms of ovarian development.