Female Crabs Research Articles

Physiological Effects of Limb Loss on the Asian Shore Crab, Hemigrapsus sanguineus

Invasive species pose a considerable threat to biodiversity and the functioning of the ecosystem. Hemigrapsus sanguineus (Asian Shore Crab) has outnumbered native crabs on the northeast coast of North America since shortly after its introduction in the late 1980s. Asian Shore Crabs occur in high densities along much of the Atlantic coast from Maine to North Carolina. Our research focused on the relationship between limb loss and energy use and storage in both male and female Asian Shore Crabs as a means of understanding their ability to reach high population densities. We sampled 154 crabs of both sexes from Odiorne Point State Park in Rye, NH. We then dissected the individual specimens and measured limb loss and the mass of the hepatopancreas (an energy storage organ) and gonads. Our findings reveal that limb loss has similarly limited impacts on male and female crabs in terms of both energy storage and reproductive effort. We conclude that despite a high frequency of injury, the energetics of Asian Shore Crabs were largely unaffected, and that this may be one reason why this species has been able to achieve sustained high densities throughout much of its invaded range.

The effect of Melastoma malabathricum leaf extract on growth and spawning of blue swimming crab (Portunus pelagicus)

The aim of this study was to evaluate the effect of Melastoma malabathricum leaf extract on growth and spawning of the blue swimming crab Portunus pelagicus. This research was conducted from March to May 2019 at the Hasanuddin University mini hatchery in Barru Regency, South Sulawesi Province, Indonesia. The study used five treatment doses of M malabathricum leaf extract: 0, 5, 10, 15, and 20μg/g of female crab body weight. The extract was dissolved in water and an aliquot of 0.1 mL was injected into each crab. The results showed that there was a decrease in growth in all treatments within the first 10 days after injection, but an increase after the 20th day. Doses of 15 and 20 ug/g resulted in the highest spawning rate, ie 100% after 30 days. Crabs with no extract treatment had the lowest spawning rate, which was only 33%. The conclusion of this study is that an appropriate dose of M. malabathricum leaf extract can be used to stimulate spawning of Portunus pelagicus.

Numerical studies on snow crab (Chionoecetes opilio) larval survival and transport in the Sea of Japan

The snow crab Chionoecetes opilio is an important fishery species in Japan. Hydrodynamics are vital to the distribution, recruitment and settlement of crab larvae in nursery areas. In this study, we developed a survival and transport model of snow crab larvae to investigate the interannual variability in larval settlement in three fishing areas: west of Toyama (region A), west of Niigata (region B) and west of Hokkaido (region C). We found that the female crab stock abundance determined the modeled number of zoea in regions A and B, whereas water temperature played a major role in the initial number of zoea in region C. As for larval settlement, the ocean current impacted settlement in region B, and water temperature was vital to settlement in region C. Both female crab abundance and hydrodynamics contributed to variability in settlement in region A. The results revealed contrasting recruitment patterns in the three fishing areas. Self-recruitment was the primary form in regions A and C, whereas both self-recruitment and recruitment from upstream sources were important in region B.

Sperm acquisition and storage dynamics facilitate sperm limitation in the selectively harvested blue crab Callinectes sapidus

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 629:87-101 (2019) - DOI: https://doi.org/10.3354/meps13104 Sperm acquisition and storage dynamics facilitate sperm limitation in the selectively harvested blue crab Callinectes sapidus Matthew B. Ogburn*, Kimberly D. Richie, Morgan A. Jones, Anson H. Hines Smithsonian Environmental Research Center, Edgewater, MD 21037, USA *Corresponding author: ogburnm@si.edu ABSTRACT: Selective harvest of male blue crabs Callinectes sapidus can reduce the operational sex ratio and alter male mating history and behaviors, reducing the quantity of sperm females acquire during mating. Females mate shortly after molting to maturity, storing sperm for at least 2 yr, and fertilize multiple broods of eggs. We combined field surveys, a mark-recapture experiment, and modeling in the most extensive study of sperm storage and use after mating in blue crabs evaluating (1) spatiotemporal patterns in sperm quantity acquired during mating, (2) the pattern and rate of decline of sperm during storage, (3) the quantity of sperm used for fertilization, and (4) the potential for sperm limitation. We also explored the spatial extent of spawning in Chesapeake Bay in comparison to the spawning sanctuary. Female crabs acquired up to 3 × 109 sperm, but sperm stores declined by 90-95% in the first 1-2 mo after mating. Sperm quantity differences between first- and second-year spawners indicated use of 4 sperm egg-1 during fertilization. Approximately 15% of spawning females were in their second spawning season, and remaining sperm stores were indicative of sperm limitation resulting in a 5-10% decrease in reproductive output of the spawning stock. The current spawning sanctuary encompassed 98% of ovigerous females and 100% of females with evidence of prior spawning. Although many females do not experience sperm limitation prior to harvest or natural mortality, reductions in the reproductive output of second-year spawners likely limits population resilience to inter-annual variation in spawning stock biomass. KEY WORDS: Sperm limitation · Population dynamics · Reproductive output · Selective harvest · Callinectes sapidus Full text in pdf format PreviousNextCite this article as: Ogburn MB, Richie KD, Jones MA, Hines AH (2019) Sperm acquisition and storage dynamics facilitate sperm limitation in the selectively harvested blue crab Callinectes sapidus. Mar Ecol Prog Ser 629:87-101. https://doi.org/10.3354/meps13104 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 629. Online publication date: October 24, 2019 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2019 Inter-Research.

Molecular characterization of yolk proteins in the female crab Neptunus pelagicus (A. Milne-Edwards, 1861) from the Mediterranean Sea of Alexandria, Egypt

This study aimed to characterize the morphological changes in the ovary of the female crab Neptunus pelagicus and to identify specific fractions of vitelloginin and vitelline molecules during primary and secondary vitellogenesis. Samples of the blue crab were collected from the Mediterranean Sea of Alexandria monthly during 2017. Ovaries and oocytes in primary and secondary vitellogenesis were detached and treated for histological test. Native polyacrylamide gel electrophoresis (PAGE) Bis-Tris Gels was applied to identify vitelloginin (VN) and vitelline (VL) molecules. Protein Analyses were done by PAGE-SDS. The initial degenerate primers were built regarding the conserved amino acid domains of the yolk proteins. Primary and secondary vitellogeneses consisted of 8 phases. Lipoprotein fraction with molecular weight 550 kDa was identified in the hemolymph in secondary vitellogenesis. Two protein fractions (VLI & VLII) were identified in secondary vitellogenic oocytes. The electrophoresis performed with extract of stage I oocyte showed two protein fractions with molecular weights 550 kDa and 460 kDa. In stage II and III oocyte, 4 subunits were presented of 180, 195, 140 and 120 kDa in VLI and 2 subunits with molecular weight of 110 kDa and 95 kDa in VLII. Another two fractions in stage V oocyte presented with molecular weights of 380 kDa and 360 kDa. Western blot analysis proved that both fractions were of four major polypeptide subunits with molecular weight of 180, 125, 90 and 85 kDa in each of the two VLs. The hybridization signal obtained by the Northern blot was detected in the hepatopancreas during ovarian cycle and in the ovary during secondary vitellogenesis. The result of the reverse transcription-polymerase chain reaction (RT-PCR) analysis showed that the mRNA that encodes the C-terminal region of the VN cDNA was found in the ovary in secondary vitellogenesis and in the hepatopancreas.

Encounters with predators fail to trigger predator avoidance in bumblebees, Bombus terrestris (Hymenoptera: Apidae)

Abstract Many species must learn to identify their predators, but little is known about the effect of direct encounters on the development of predator avoidance. We asked whether bumblebees, Bombus terrestris, learn to avoid predators, whether learning depends on the conspicuousness of predators and whether bumblebees learn to identify predators or simply to avoid dangerous patches. To answer these questions, we allowed bumblebees to forage in an enclosed meadow of 15 artificial flowers containing a yellow female crab spider, Thomisus onustus. Flowers were yellow in half of the trials and white in the other half. Spiders could remain at the same flower throughout the experiment or swap flowers between bee foraging bouts. Of the 60 bees used in the experiment, eight were killed by the spiders and nine stopped foraging without finishing the trial. Death or refusal to forage typically occurred early in the trial. Regardless of the treatment, the probability of landing at the spider-harbouring flower increased with time. Previous encounters with heterospecific individuals can therefore be a poor source of information about their predatory nature.

Borealis awards engineering services (EPCM) contract to Maire Tecnimont Group for new world-scale propane dehydrogenation plant in Belgium

Intestinal microflora, as a component of the host bacteria ecosystem, can influence the healthy growth of crab. The aim of this study was to determine the intestinal microflora of the juvenile Chinese mitten crab Eriocheir sinensis with different feeding modes. We investigated the bacterial communities of crab intestine resulting from three different feeding modes using high-throughput sequencing technology, including traditional, formulated, and mixture (combined traditional and formulated) diet feeding modes. Intestinal microbiota biodiversity and richness were not affected by the different feeding modes. The most dominant community members at the phylum level were Tenericutes, Bacteroidetes, Firmicutes, and Proteobacteria. Significant differences were only observed in the relative abundance of Tenericutes (P = 0.0390) and Proteobacteria (P = 0.0273) in the female crab intestines among different feeding modes. The seven most abundant genera in the intestine of male and female crabs included Candidatus Bacilloplasma, Candidatus Hepatoplasma, Prolixibacter, Vibrio, Dysgonomonas, Coprobacillus, and Lactovum. Moreover, high average similarity of the microbial community was observed in the intestine of male and female crabs among the three different feeding modes and also between male and female crabs within these feeding modes. The most abundant genera in the latter (>10%) were Candidatus Bacilloplasma, Candidatus Hepatoplasma, and Prolixibacter. In addition, unique microbial genera were found in male or female crab intestine among different feeding modes. Differences were also observed in the relative enrichment of the dominant bacteria in male and female crab intestine among different feeding modes. Nevertheless, these findings suggested that the microbial communities in the intestines of crabs showed overall high average similarity among the three feeding modes or between the sexes as reflected by the biodiversity, richness of intestinal microbiota, and the most dominant community members at the phylum and genera levels. The results of this study provide a theoretical reference regarding the diversity of intestinal bacteria in juvenile E. sinensis.

Lipid Peroxidation in Hepatopancreas, Gill, and Hemolymph of Male and Female Crabs Platyxanthus Orbignyi after Air Exposure

Levels of lipid peroxidation in hepatopancreas (HP), gill (G), and hemolymph (HYM) of stone violaceous crab Platyxanthus orbignyi (Milne Edwards and Lucas (1843)) were performed to examine the effect of short exposure to air. After four hours animals were collected, 14 from exposure to air and 10 from seawater were dissected and their lipid peroxidation (LPO) levels were evaluated using the ferrous oxidation-xylenol orange (FOX) method, in gill, hepatopancreas, and hemolymph. The total mortality of those crabs was evaluated after seven hours at 22 ± 1 °C on exposure to air conditions. Levels of LPO in hepatopancreas (female/male = 4.68 ± 1.60/5.12 ± 1.59 Eq-H2O2/g wet tissue) and hemolymph (female/male = 1.48 ± 1.42/1.28 ± 1.06 Eq-H2O2/g wet tissue) displayed no significant differences, in contrast, gills displayed significant differences (male/female = 5.63 ± 0.83/4.63 ± 0.44 Eq-H2O2/g wet tissue, p < 0.05). The results showed that air exposure in the short term in this study induces a different response in oxidative stress levels and damage could be accompanied by accumulation of peroxide lipids (LOOH). These results suggest that different organs can show different responses to oxidative stress between male and female crabs to this species.

Microbiota comparison in the intestine of juvenile Chinese mitten crab Eriocheir sinensis fed different diets

Intestinal microflora, as a component of the host bacteria ecosystem, can influence the healthy growth of crab. The aim of this study was to determine the intestinal microflora of the juvenile Chinese mitten crab Eriocheir sinensis with different feeding modes. We investigated the bacterial communities of crab intestine resulting from three different feeding modes using high-throughput sequencing technology, including traditional, formulated, and mixture (combined traditional and formulated) diet feeding modes. Intestinal microbiota biodiversity and richness were not affected by the different feeding modes. The most dominant community members at the phylum level were Tenericutes, Bacteroidetes, Firmicutes, and Proteobacteria. Significant differences were only observed in the relative abundance of Tenericutes (P = 0.0390) and Proteobacteria (P = 0.0273) in the female crab intestines among different feeding modes. The seven most abundant genera in the intestine of male and female crabs included Candidatus Bacilloplasma, Candidatus Hepatoplasma, Prolixibacter, Vibrio, Dysgonomonas, Coprobacillus, and Lactovum. Moreover, high average similarity of the microbial community was observed in the intestine of male and female crabs among the three different feeding modes and also between male and female crabs within these feeding modes. The most abundant genera in the latter (>10%) were Candidatus Bacilloplasma, Candidatus Hepatoplasma, and Prolixibacter. In addition, unique microbial genera were found in male or female crab intestine among different feeding modes. Differences were also observed in the relative enrichment of the dominant bacteria in male and female crab intestine among different feeding modes. Nevertheless, these findings suggested that the microbial communities in the intestines of crabs showed overall high average similarity among the three feeding modes or between the sexes as reflected by the biodiversity, richness of intestinal microbiota, and the most dominant community members at the phylum and genera levels. The results of this study provide a theoretical reference regarding the diversity of intestinal bacteria in juvenile E. sinensis.

Growling from the gut: co-option of the gastric mill for acoustic communication in ghost crabs.

Animal acoustic communication systems can be built upon co-opted structures that become specialized for sound production or morphological novelties. The ghost crab, Ocypode quadrata, evolved a novel stridulation apparatus on the claws that is used during agonistic interactions, but they also produce a rasping sound without their claw apparatus. We investigated the nature of these sounds and show that O. quadrata adopted a unique and redundant mode of sound production by co-opting the gastric mill (grinding teeth of the foregut). Acoustic characteristics of the sound are consistent with stridulation and are produced by both male and female crabs during aggressive interactions. Laser Doppler vibrometry localized the source of maximum vibration to the gastric region and fluoroscopy showed movement of the gastric mill that coincided with stridulation. The lateral teeth of the gastric mill possess a series of comb-like structures that rub against the median tooth to produce stridulation with dominant frequencies below 2 kHz. This previously undescribed gastric stridulation can be modulated and provide a means of assessment during aggressive interactions, similar to the use of the claw stridulation apparatus. This functional redundancy of stridulation in crabs offers unique insights into the mechanisms of evolution of acoustic communication systems.

Mitochondrial genotype influences the response to cold stress in the European green crab, Carcinus maenas.

Hybrid zones provide natural experiments in recombination within and between genomes that may have strong effects on organismal fitness. On the East Coast of North America, two distinct lineages of the European green crab (Carcinus maenas) have been introduced in the last two centuries. These two lineages with putatively different adaptive properties have hybridized along the coast of the eastern Gulf of Maine, producing new nuclear and mitochondrial combinations that show clinal variation correlated with water temperature. To test the hypothesis that mitochondrial or nuclear genes have effects on thermal tolerance, we first measured the response to cold stress in crabs collected throughout the hybrid zone, then sequenced the mitochondrial CO1 gene and two nuclear single nucleotide polymorphisms (SNPs) representative of nuclear genetic lineage. Mitochondrial haplotype had a strong association with the ability of crabs to right themselves at 4.5°C that was sex specific: haplotypes originally from northern Europe gave male crabs an advantage while there was no haplotype effect on righting in female crabs. By contrast, the two nuclear SNPs that were significant outliers in a comparison between northern and southern C. maenas populations had no effect on righting response at low temperature. These results add C. maenas to the shortlist of ectotherms in which mitochondrial variation has been shown to affect thermal tolerance, and suggest that natural selection is shaping the structure of the hybrid zone across the Gulf of Maine. Our limited genomic sampling does not eliminate the strong possibility that mito-nuclear co-adaptation may play a role in the differences in thermal phenotypes documented here. Linkage between mitochondrial genotype and thermal tolerance suggests a role for local adaptation in promoting the spread of invasive populations of C. maenas around the world.

Different biochemical composition and nutritional value attribute to salinity and rearing period in male and female mud crab Scylla paramamosain

Crabs show major differences in biochemical composition and nutritional value responding to various culture environments, growth stages and even sexes. In the present study, juvenile mud crab Scylla paramamosain (0.026 ± 0.010 g) were cultured at two earthen ponds with the respective salinity level of 25‰ and 5‰ for four months. The proximate composition, amino acid content and fatty acid profile in edible parts (muscle and hepatopancreas) of male and female crabs reared at different salinities and two rearing periods (three-month stage: 60–120 g and four-month stage: 150–300 g) were investigated and compared. Crabs at high salinity had significantly lower moisture contents in muscle and hepatopancreas, but had higher protein contents in muscle and higher ratio of n-3/n-6 highly unsaturated fatty acids (PUFA) in both edible parts, regardless of gender and rearing period. Additionally, significant differences in biochemical composition and nutritional value were also found between male and female crabs. For example, the contents of crude protein and most amino acids were higher in muscle and hepatopancreas of females, whereas males contained higher n-3 PUFA contents in both edible parts. Further, the contents of delicious amino acids (DAA) and essential amino acids (EAA) in muscle and the crude lipid content in hepatopancreas exhibited a higher trend at three-month stage than that at four-month stage. The results suggested that S. paramamosain reared at high salinity had better nutritional value than that at low salinity, while female and male crabs possess their respective advantages in terms of different nutritional composition. In addition, crabs had a better nutritional quality at three-month stage, even though they were at a smaller size.

Growth performance and survival rate of Portunus pelagicus (Linnaeus, 1758) broodstock females fed varying doses of amaranth extracts

Background: Formulated diets made from food waste enriched with amaranth extract largely determine the level of softshell crab production. The study was carried out to analyze the growth performance and survival rate of blue swimming crab Portunus pelagicus (Linnaeus, 1758) broodstock females fed formulated diets with different doses of amaranth extracts. Methods: The female crab samples were collected from the coastal region of Padang, West Sumatra. The method used in this study was a completely randomized design, with four treatments and five replications of amaranth extract-enriched diets (0, 250, 500, and 750 ng/g crab). Results: The results show that the enrichment of the formulated diet with amaranth extracts significantly affected (P < 0.05) the absolute weight gain (AWG), carapace length (ACL), and carapace width (ACW). Conclusions: A quadratic relationship existed between the amaranth extract dose in the formulated diet and the AWG, ACL and ACW.

Abundance and Growth Parameter of Mangrove Crab (Scylla serrata) in Estuary Water of Karang Gading, District Deli Serdang

Research about the abundance and growth parameter of mangrove crab Scylla serrata in the estuary water of Karang Gading, District Deli Serdang has been done. The aims of this research are to analyze the abundance, frequency distribution of wide carapace, and growth parameter of mangrove crab. This research use purposive sampling methods. Sampling of mangrove crab use bubu, and data analysis use the equation according to Bengen and Fish Stock Assesment Tool (FISAT II). The study obtained 146 individu of male crabs and 192 individu of female crabs. The abundance of male mangrove crabs is 88 ind m3-1 and female crabs 116 ind m3-1 . The highest value of mangrove crab abundance was found at station 4 of 68 ind m3-1 consisting of 17 male crabs and 51 female crabs, and the lowest in station 1 was 37 ind m3-1 consisting of 23 male crabs and 14 female crabs. Distribution of mud crab is included in the group distribution pattern. The male crabs takes 4 month to reach maximum carapace width, and female crab takes 5 month.

Condition Factor and Exploitation Rates of Scylla serrata in Karang Gading Sumatera Utara

Research about the condition factor and exploitation rates of Scylla serrata in Karang Gading Sumatera Utara has been done. The aims of the research are to measure and determine of S. serrata growth patterns, condition factors, the time needed for S. serrata to reach the maximum carapace width, and exploitation rates of S. serrata in Karang Gading Sumatera Utara. This research uses purposive sampling methods. Sampling of S. serrata use bubu, and data analysis use Fish Stock Assesment Tool (FISAT II). The study found that the growth pattern of S. serrata is allometric negative, meaning that the increase in body length is faster than weight gain. Based on the value of the condition factors, S. serrata in Karang Gading Sumatera Utara have a thin body. S. serrata of male take 5 months to reach a maximum carapace width of 13.2 cm, while female crab take 6 months to reach a maximum carapace width of 14.8 cm. The rate of exploitation of S. serrata in Karang Gading Sumatera Utara is still underfishing.

Reproductive biology of Charybdis (Goniohellenus) longicollis Leene, 1938 (Brachyura: Portunidae), in the north-eastern Mediterranean Sea, Turkey

The swimming crab, Charybdis (Goniohellenus) longicollis Leene, 1938, is a Lessepsian migrant into the Mediterranean and little is known about its biology in Iskenderun Bay, north-eastern Mediterranean, Turkey. The size of crabs, sex-ratio and spawning period of this species was defined from 951 specimens in order to understand their reproduction and development in the NE Mediterranean Sea. The crabs were found to occur throughout the year. Carapace width (CW) ranged between 7.22 to 100.60 mm and total weight ranged from 1.34 to 164.09 g. Male-female sex ratio was 0.6:1. Highest gonado-somatic index (GSI) was seen in March and September for females and in May for males. Ovigerous females were present throughout the year, with peak spawning activity in July and September. The CW of the ovigerous female crabs ranged between 23.71 and 95.93 mm. In winter months, GSI of males and females decreased. However, spawning season of C. (G.) longicolis in Yumurtalık Cove was observed throughout the year.

The sounds of fighting: contests between violet vinegar crabs, Episesarma versicolor (Tweedie, 1940) (Decapoda: Brachyura: Sesarmidae), are resolved through acoustic communication

Abstract Sound plays an important role in animal communication. Sesarmid crabs (family Sesarmidae) are semi-terrestrial crabs found in tropical and temperate regions, and are known to communicate through acoustic signals. The violet vinegar crab Episesarma versicolor (Tweedie, 1940) is a tree-climber known to possess sound-producing structures. The significance of sounds produced by E. versicolor during intraspecific contests, however, remains unknown. We investigated the context in which sound production occurs by staging 27 trials using male crabs. Three main types of acoustic behaviours were documented: rapping, leg stamping, and vibration. With the exception of vibration, these behaviours were also observed in female crabs. The air or the wood substrate was utilised to transmit acoustic signals, with each sound having unique spectral and temporal features serving different purposes. Rapping and leg stamping may be an advertisement of the sender’s resource-holding potential for territorial defence and asserting dominance during fights. Vibration is likely a victory display that discourages the contest loser as well as individuals in the vicinity from engaging the victor in another fight. Episesarma versicolor can therefore produce acoustic signals that may contain information about the sender, minimising costs associated with direct conflicts.

Cracking the cuisine: Invasive European shore crabs (Carcinus maenas) select a menu of soft-shelled mussels over cockles

The European shore crab, Carcinus maenas, is known to feed extensively on a variety of benthic species, and can affect commercially important bivalve fisheries. As a marine invasive species, predation by C. maenas can have ecological and commercial effects in its non-native range. We investigated potential predatory effects of non-indigenous C. maenas on native bivalves, and if shell strength of bivalve prey influenced predation susceptibility. The main prey species tested were ecosystem-engineering mussels (Mytilidae, Xenostrobus inconstans), and commercially valuable mud cockles (Veneridae, Katelysia peronii.). In separate field experiments, crabs were offered either a choice between both bivalve species or non-choice for each species separately. Male and female crabs equally consumed mussels across both choice and non-choice experiments. The proportion of cockles consumed was significantly lower than that of mussels in choice experiments, and no cockles were consumed in the non-choice experiment. Bivalve compressive shell strengths were tested separately with a universal testing machine. The breaking force required to crush shells of adult K. peronii was much higher than the claw strength of adult crabs, but the significantly lower shell-breaking forces required for X. inconstans make the mussels vulnerable prey. Additional compressive shell strength tests on other native bivalve species and juvenile Katelysia showed that they were susceptible to crab predation. Results indicate that predation by non-indigenous C. maenas on soft-shelled mussels and juvenile cockles could impact native bivalve abundances. Shell strength measurements of potential prey are a suitable approach to assess the risk for ecological and economic impacts of this globally invasive crab.

Record of Chaceon alcocki Ghosh & Manning, 1993 from the Arabian Sea, off Kollam, India

Abstract The deep-sea crab Chaceon alcocki Ghosh & Manning, 1993 was recorded from the Arabian Sea off the Kollam coast, Kerala, India, in November 2015. A single female crab with 156 mm carapace width (CW), 146 mm carapace length (CL) and a total weight (TW) of 655 g, was collected from multiday trawl landings at the Sakthikulangara landing centre, Kollam, Kerala state. This species was first described by Ghosh & Manning in 1993, and the holotype, also a female crab, is kept in the Zoological Survey of India, Kolkata [formerly known as Calcutta].

Defatted Haematococcus pluvialis meal can enhance the coloration of adult Chinese mitten crab Eriocheir sinensis

Defatted algal meal, a by-product of carotenoid extraction from Haematococcus pluvialis, still contains a certain level of astaxanthin and other nutrients, which is considered as a potential ingredient or additive for aquafeeds. This study was conducted to investigate the effects of dietary supplementation of defatted H. pluvialis on gonadal development, coloration, and antioxidant and immune capacity of adult Chinese mitten crab, Eriocheir sinensis. Three isonitrogenous (crude protein: 42% of dry diet) and isolipidic (crude lipid: 16% of dry diet) experimental diets were formulated to contain 1% defatted H. pluvialis meal (Diet 1), 0.2% whole H. pluvialis powder (Diet 2), and without supplementation of astaxanthin (Diet 3, control diet). Therefore, there were three treatments with four replicate tanks for each treatment, and each tank had 12 crabs (6 males and 6 females). For the color parameters, no significant differences were found between Diet 1 and 2 treatments. The values of hepatopancreas lightness (L* = 62.65) and carapace redness (a* = 20.29) of male crabs from Diet 1 treatment were significantly higher compared to those (L* = 53.94, a* = 17.87) of Diet 3 treatment; while the a* values of ovaries (a* = 26.28) and carapace (a* = 19.93) of female crabs from Diet 1 treatment were significantly higher than those (ovarian a* = 18.28, carapace a* = 16.30) of Diet 3 treatment. The total carotenoids contents in the hepatopancreas (243.73 mg kg −1 dry matter) and carapace (73.44 mg kg −1 dry matter) of male crabs fed Diet 1 were higher than those (133.50, 43.14 mg kg −1 dry matter) of Diet 3 treatment. The contents of total carotenoids in the ovaries (356.50 mg kg −1 dry matter), hepatopancreas (120.88 mg kg −1 dry matter) and carapace (79.61 mg kg −1 dry matter) of females fed Diet 1 were significantly higher than those (290.92, 76.04 and 61.77 mg kg −1 dry matter, respectively) of Diet 3 treatment; while the astaxanthin contents in the ovaries (174.69 mg kg −1 dry matter) and carapace (19.97 mg kg −1 dry matter) of females from Diet 1 treatment were significantly higher than those (25.65, 13.87 mg kg −1 dry matter) in the Diet 3 treatment. For the antioxidant capacity indices, the male crabs from Diet 1 treatment had the lower levels of superoxide dismutase, peroxidase, glutathione reductase and malondialdehyde in the serum as well as the activities of glutathione peroxidase and peroxidase in the hepatopancreas than those of Diet 3 treatment (P < .05), but no significant differences were found between Diet 1 and 2 treatments. For the immune indices, dietary supplementation with defatted H. pluvialis significantly increased the activities of acid phosphatase, alkaline phosphatase in the serum of male crabs as well as the levels of serum alkaline phosphatase, hemocyanin and nitric oxide of female crabs compared to Diet 3 treatment (P < .05). In conclusion, dietary supplementation of defatted H. pluvialis meal can enhance the coloration, antioxidant and immune capacity, and reduce the cost of a fattening diet for E. sinensis.