Sea Cucumber Species Research Articles

Effects of anthropological factors on the metal accumulation profiles of sea cucumbers in near industrial and residential coastlines of İzmir, Turkey

ABSTRACTThis study details the metal and metalloid accumulation profiles of three species of sea cucumbers (Holothuriamammata, Holothuriapolii and Holothuriatubulosa) native to Aliağa and Ildır (İzmir, Turkey), two regions that are representative of industrial and residential districts, respectively. A total of 11 elements were analysed (Fe, Cu, Mn, Zn, Cr, Co, V, Ni, Cd, Pb and As) from gut and body wall tissues of holothurians and in sediment samples. The Mann–Whitney U analysis revealed statistical difference between locations and tissues. Accumulations of Aliağa samples were significantly higher than Ildır samples with respect to Zn, V, Mn, Cr, Fe and Co while accumulations were significantly higher in the gut than body wall regardless of the region for all elements tested. The correlation analysis showed more and stronger correlations in the gut than in the body wall. In addition, metal(loid) concentrations in the sediment were found to correlate strongly with these in the sea cucumber gut. The cluster analysis displayed totally different element accumulation pattern for Aliağa and Ildır in the both tissues which indicate that anthropogenic effects start to alter the bioaccumulation of metal(loids). Biota-sediment accumulation factors (BSAF) and metal contamination index were calculated to determine the extent of metal(loid) uptake and to compare total elemental accumulation at each region. Gut tissue elemental BSAF is higher than body wall for all elements at both areas. Cd has the highest value with 5.582 (gut tissue) and the lowest are Ni, V and Cr with 0.001 (body wall tissue). In addition, sediment results were compared with previous studies and sediment quality guidelines and found to exceed the lowest effect level (LEL) values for As and Ni.

KOMPOSISI SPESIES TERIPANG (Holothuroidea) DI PERAIRAN KAMPUNG KAPISAWAR DISTRIK MEOS MANSWAR KABUPATEN RAJA AMPAT

This study aimed to investigate the species and its composition of sea cucumber in the Kapisawar village of Meos Manswar District in Raja Ampat Regency. This research was conducted from March to April 2014. Descriptive method was applied directly through observations by using belt transects that consisted of three stations. Then, identification of species was done through spicula appearance of sea cucumbers. Results showed that from all research stations, 10 species of sea cucumbers were found, and these species derived from 3 families and 4 genera. The species of sea cucumbers are Holothuria scabra, H. leucospilota, H. rigida, H. sucosa, Bohadschia similis, B. marmorata, B. vitiensis, Synapta maculate, Opheodesoma grisea and Stichopus variegatus. The highest number of sea cucumber species was found in the station I which consisted of 9 species from 2 families and 4 genera, followed by station II (2 families and 3 genera), and the lowest at the station III of 3 species (2 families and 2 genera). Some of the sea cucumber found in the research station were economic importance, with the highest composition was at the station I because of its suitable habitat condition and the lowest in station III due to far from the village.

Short Communication: DNA barcoding reveals vulnerable and not evaluated species of sea cucumbers (Holothuroidea and Stichopodidae) from Kepulauan Seribu reefs, Indonesia

Madduppa H, Taurusman AA, Subhan B, Anggraini NP, Fadillah R, Tarman K. 2017. DNA barcoding reveals vulnerable and not evaluated species of sea cucumbers (Holothuroidea and Stichopodidae) from Kepulauan Seribu reefs, Indonesia. Biodiversitas 18: 893-898. DNA Barcoding is a tool in the molecular taxonomy which allows a rapid and precise identification. This tool is needed to mitigate difficulties in identifying species of sea cucumbers in Indonesia. This study was conducted to reveal species diversity in sea cucumbers (Holothuridae and Stichopodidae), commonly harvested in the Kepulauan Seribu reefs, northern Jakarta, Indonesia, by using mitochondrial DNA. Neighbor-joining phylogenetic trees were reconstructed using the Kimura-2 parameter with 1000 of bootstrap values. The genetic distance within and between species was investigated. Conservation and trade status of the species were determined using IUCN and CITES, respectively. DNA barcoding using mitochondrial Cytochrome oxidase 1 (COI) revealed 7 species from 96 samples, of which 4 species belonged to the Stichopodidae (Stichopus herrmanni, Stichopus ocellatus, Stichopus horrens, Stichopus monotuberculatus), and 3 species to the Holothuridae (Bohadschia bivittata, Actinopyga lecanora and Holothuria leucospilota). Phylogenetic analysis showed that the two families were separated with a high bootstrap value. The neighbor-joining tree supported the result of identification of the sea cucumber species. The ingroup haplotypes were clustered into four main clades. Stichopus herrmanni and S. ocellatus were identified as closely related, which matches their morphological characteristics. Bohadschia bivittata is the most distinct species from other species due to the formation of a separate clade in the phylogenetic tree. Stichopus. horrens and S. monotuberculatus were also identified as very closely related, which might explain the frequent morphological misidentification of both types. The conservation status determined one of the investigated species was categorized as vulnerable, one as least concern, one as not evaluated, and four species in data deficient. The population trend of S.s herrmanni was recorded to be decreasing, whereas it remained unknown for the other 6 species. Surprisingly, all identified species in this study were not evaluated yet by CITES. This study suggests that a proper field monitoring and the establishment of a valid list of commercial and scientific names for the sea cucumbers harvested in Kepulauan Seribu is necessary. This would be valuable for keeping trade records and managing and conserving the targeted sea cucumber species in the region.

New records of sea cucumbers inhabiting Mar Menor coastal lagoon (SE Spain)

Two sea cucumber species, Holothuria impatiens and Oestergrenia digitata, were reported officially on Mar Menor coastal lagoon (SE Spain). Seven specimens of the first species were identified, using traditional taxonomy and genetic barcoding, in Los Narejos (Mar Menor). However, only one belonging to O. digitata species was found in Los Urrutias (Mar Menor). These findings could support the ‘mediterranisation’ process of the lagoon favoured by the enlargement of the El Estacio inlet in 1972. In the last several years, there has been a decrease in salinity, a smoothing of the most extreme temperatures and many anthropogenic actions which have produced modifications in Mar Menor, affecting the seagrass and seaweed coverage and causing an increase of organic matter in sediments. These modifications, together with the current patterns, are favouring the colonisation of Mar Menor by Mediterranean species.

Nutritional Composition of Selected Species of Sea cucumbers from Waters around Jaffna Peninsula, Sri Lanka

Biochemical studies (protein, fat, moisture and ash) were done on five species of holothurians namely Holothuria leucospilota, Holothuria scabra, Holothuria spinifera, Stichopus naso and Thelenota anax , which were collected from the waters around Jaffna Peninsula during November 2013 to April 2014. Moisture, ash, protein and lipid contents of collected sea cucumbers were measured and recorded. The average moisture, protein, lipid and ash contents were 84.52±0.88%, 10.06±0.04%, 0.25±0.02% and 1.90±0.07% in H. leucospilota, 85.21±0.78%, 4.96±0.02%, 0.34±0.03% and 5.72±0.34% in H. scabra, 79.19±0.86%, 8.22±0.43%, 0.27±0.05% and 9.22±0.23% in H. spinifera , 92.55±0.66%, 3.00±0.04%, 0.33±0.01% and 1.62±0.02% in S. naso and 89.92±1.33%, 3.14±0.03%, 0.40±0.02% and 2.90±0.01% in T. anax , respectively. Marked significant differences (p H. leucospilota and H. spinifera possessed higher protein, T. anax possessed higher lipid and H. spinifera possessed higher ash contents than other investigated sea cucumber species. Among the five analyzed sea cucumber species, H. leucospilota is the most recommended as one of the healthiest food for human consumption as it has low fat content and high protein content.

Two fucosylated chondroitin sulfates from the sea cucumber Eupentacta fraudatrix

Two fucosylated chondroitin sulfates EF1 and EF2 were isolated from the sea cucumber Eupentacta fraudatrix. Separation of the polysaccharides was performed using anion-exchange chromatography on DEAE-Sephacel by elution of 0.75M and 1.0M NaCl solutions. The structures of biopolymers were determined by chemical and NMR spectroscopic methods. The backbone of EF1 was found to be composed of chondroitin sulfate A and E units in a ratio of about 1:1. The core of EF2 along with chondroitin sulfate A and E fragments contained unusual disaccharide repeating units →4)-β-d-GlcpA2S3S-(1→3)-β-d-GalpNAc6S-(1→. The main type of branches in both polysaccharides was α-l-Fucp3S4S unit attached to O-3 of GlcA residues. Another type of branches was found to be the disaccharide fragment α-l-Fucp-(1→2)-α-l-Fucp3S4S-(1→ linked to O-3 of GlcA. The presence of structurally different fucosylated chondroitin sulfates in one species of sea cucumber is rather unusual and has not been described previously.

Comparison of Fatty Acid and Proximate Composition between <i>Holothuria edulis</i> and <i>Holothuria scabra</i> Collected from Coastal Water of Sabah, Malaysia

The nutritional values of different species of sea cucumber are greatly concerned because of their dietary and curative properties. In this study, two species of sea cucumber, Holothuria edulis, a low-valued noncommercial species, and Holothuria scabra, a high-valued commercial species were selected to compare its proximate composition and fatty acids. H. edulis a prevalent species in coastal water of Sabah is not commercially importance like H. scabra. Sea cucumbers were captured live from the Sabah marine habitat. All samples were immediately eviscerated, freeze-dried and stored at 4°C in until analyzed. Silylating agent N, O-Bis(trimethylsilyl) trifluoroacetamide (BSTFA) was used to derivitization of fatty acid prior to gas chromatography-mass spectrometry (GC-MS) analysis. Proximate compositions (%), such as moisture, crude protein, crude lipids and ash were carried using standard methods. Major fatty acids in H. edulis and H. scabra were saturated fatty acid (SFA) accounted for 83.95% and 98.60%, respectively and dominated with Palmitic acids. Polyunsaturated fatty acid (PUFA), arachidonic acid of 16.05% was found only in H. edulis, but absent H. scabra. Proximate compositions (dry weight) were varied greatly within these two species. Moisture, crude protein, crude lipids and ash of 85.5%, 70.5%, 1.37% and 1.27% respectively were obtained in H. edulis. On the other hand 84.5% of moisture, 51.2% of crude protein, 0.27% of crude lipids and 4.44% of ashes were determined in H. scabra. Significantly higher protein (p < 0.05) content and detection of PUFA in H. edulis compare to H. scabra could be the choice of option for the utilization of this non commercial species as nutraceutical industry and also alternatives to reduce the pressure on heavily exploited species of H. scabra.

Surveillance study on the most common sea-cucumbers in some Egyptian coasts

Sea cucumbers depletion has become a threat to Egypt because of the extreme harvesting and utility of sea cucumbers for their direct value as food and as source for bioactive products. Therefore, it is necessary to have an updated overview about the current available species in Egyptian fauna, including distribution, anatomy and morphological analysis. Six species of sea-cucumbers were collected from Egyptian coasts (Mediterranean and Red Seas). One of these species, namely Holothuria polii is collected from Mediterranean Sea coasts (Abu-Qir and Miami regions, Alexandria) while, the other five species were found in Hurghada shores. The collected species were identified and separated according to morphometric analysis. The variation of morphological characters between collected samples and their distribution along Egyptian coasts were discussed. The obtained results revealed that Holothuria leucospilota, Holothuria edulis, Bohadschia marmorata and Actinopyga mauritiana can emit fine sticky mass named Cuvierian tubules from their anus while, Holothuria atra and Holothuria polii lack this tubule. In addition, there is a significant difference between Actinopyga mauritiana and other genera in the presence of five distinct teeth around the anus.

Optimum Dose of Sea Cucumber (Stichopus Chloronotus) Extract for Wound Healing

In Malaysia, sea cucumber is also known as Gamat. Among the Malays, Gamat is frequently used as a traditional or folk medicine to relieve pain, to treat wounds and burns. It is also used as a tonic to provide extra energy. Stichopus chloronotus is one of the species of sea cucumber which is found in Malaysia. An experimental study was carried out to determine the optimum dose of aqueous extract of Stichopus chloronotus on the healing of wounds in rat model. A series of concentrations 0.1%, 0.5% and 1% aqueous extract emulsifying ointment mixed with Stichopus chloronotus was applied once a day for 10 days on the excision wound model. Changes in the wound area were measured using a caliper and photographs were taken on day 1, 3, 6, 8 and 10 after the wound creation. The wound reduction rate and macroscopic observation were evaluated to determine the optimum dose concentration. Results demonstrated that percentage of wound reduction and macroscopic observation of 0.5% aqueous extract Stichopus chloronotus emulsifying ointment mixed group was significantly higher than the other groups from day 6 following wound creation. In conclusion, 0.5% aqueous extract of Stichopus chloronotus emulsifying ointment mixture demonstrated the best dose for wound healing in a rat model.

Timun Laut Teluk Ambon, Maluku

&lt;strong&gt;Sea Cucumbers of Ambon Bay, Maluku.&lt;/strong&gt; Research on the diversity of marine life in Indonesian waters, particularly in Ambon Bay, Maluku, had started in 1705 by G.E. Rumphius. In the period thereafter until the year 2000s there was a possibility in changes of environmental conditions or habitat in Ambon Bay waters. Therefore, a study on the status of marine life in the waters of Ambon Bay and surrounding areas needed to be done. The research aimed to inventory sea cucumbers in Ambon Bay, which was conducted in July–October 2009 at 12 research stations. The method used was a free hand picking collection using snorkeling and scuba equipment. The result showed 18 species of sea cucumbers, two species of which (Holothuria atra, Opheodesoma grisea) have a wide distribution and habitat preference since they found in four to five sampling stations. The results of this inventory coupled with the results of previous studies based on literatures from 1990 showed there were 46 species of sea cucumbers in Ambon Bay, which were about 13% of the estimated number of sea cucumber species in Indonesia (±350 species). Fluctuations in the number and composition of sea cucumber species that successfully inventoried during the period of 1990s to this study are discussed in detail in this paper. There is a possibility to obtain new records, even new species in this location, along with the increase of understanding in method selection and species identification. &lt;br /&gt;&lt;br /&gt;

Partial structural studies of fucosylated chondroitin sulfate (FuCS) using attenuated total reflection fourier transform infrared spectroscopy (ATR-FTIR) and chemometrics

The compound fucosylated chondroitin sulfate from three sea cucumber species Holothuria atra, Stichopus horrens, and Holothuria arenicola was extracted and purified using strong ion exchange chromatography. The structure and sulfation patterns on their fucose branches were partially characterized and compared using liquid, gas chromatography-mass spectrometry, infrared spectroscopy, and chemometrics. The monosaccharide composition was consistently a 1:1 molar ratio of glucuronic acid to N-acetylgalactosamine while the fucose molar ratio was statistically different among the three species. Normal IR spectra exhibited a broad band at the region of 850–830cm−1 assigned to the sulfate COS group. This band was resolved in the second derivative spectra into two or three bands corresponding to the difference of sulfation patterns among sea cucumber species. Principal component analysis (PCA) confirmed the difference in the sulfate substitution region with additional discrimination of the combination amide NH and CO group, sulfate SO region, and skeletal region 1050–980cm−1. The hierarchical clustering analysis (HCA) successfully grouped each sea cucumber FuCS in the same cluster. Nevertheless, the comparison of the FuCS structure was simplified using chemometrics analysis.

Growth of Hatchery‐reared Juveniles of the Australasian Sea Cucumber, Australostichopus mollis, Fed with Artificial and Natural Diets

AbstractAustralostichopus mollis is the most common and valuable sea cucumber species on the coasts of New Zealand and southern Australia. However, information supporting the development of artificial diets to advance the aquaculture of this species is scarce. In this study, the nutrient absorption, growth, pigmentation, and survival of small (111 mg) and large (434 mg) early juveniles were measured. The juveniles were fed with mussel biodeposits (MB); a commercial hatchery diet‐powdered macroalgae (HD); and artificial diets with different protein levels, 5% (5P) and 10% (10P), respectively. During the experiment, survival was greater than 66% in all diet treatments, with the juveniles feeding actively and absorbing all major macronutrients. The small juveniles, which were starting pigmentation, had higher growth rates (0.8–2.5%/d) than the large juveniles (0.2–1.2%/d), which were completing pigmentation. Growth was higher with the MB and HD diets than with the 5P and 10P diets, which could be explained by differences in the food consumption and nutrient absorption among the diet treatments. This study shows the feasibility of developing artificial diets without depending on naturally available ingredients; however, palatability and consumption need to be improved in order to make artificial diets for this species more effective and commercially available.

Extremely low genetic variability within and among locations of the greenfish holothurianStichopus chloronotusBrandt, 1835 in Okinawa, Japan

The greenfish sea cucumber Stichopus chloronotus is an economically and ecologically important sea cucumber species throughout its range. This species is widely distributed, inhabiting coral reefs of the Indo-Pacific Ocean. Our study evaluated population genetic structure and levels of genetic diversity in southern Japan. A total of 180 individuals were collected from eight locations from Okinawa and Okinoerabu Islands and sequenced using mitochondrial 16S ribosomal DNA (16S) and nuclear histone H3 (H3) gene. Only three 16S haplotypes were detected (518 bp) with haplotype diversity ranging from 0 to 0.56 and nucleotide diversity from 0 to 0.1%. H3 showed no variation among the studied locations. It is plausible that such results could be due to a shift to asexual reproduction. Additionally, the presence of the species on the east coast of Okinawa could only be detected in one location and all individuals consisted of a single haplotype. Genetic differences between the east and west coasts of Okinawa have been noticed in other coral reef organisms, and attributed to either ecological or biogeographical historical differences between the coasts due to differing levels of isolation during Pleistocene ice ages. Results from the present study should inform management and conservation policies of S. chloronotus in southern Japan.

Recovery rates for eight commercial sea cucumber species from the Fiji Islands

Determination of the original weight and length of sea cucumbers processed and dried to become bêche-de-mer (BDM), is an important tool in sea cucumber fishery management. The only management mechanism for the sea cucumber fishery in the Fiji Islands is a minimum length prescribed for BDM for export. However, different commercial species have different shrinkage rates during processing and previous studies have suggested modification of fisheries management for sea cucumbers to include species-specific minimum harvest size limits This study determined weight-based and length-based recovery rates (i.e. the length/weight of BDM recovered after processing from the initial length/weight of fresh sea cucumber), for eight commercial sea cucumber species following processing to BDM; White Teatfish (Holothuria fuscogilva), Black Teatfish (Holothuria whitmaei), Tigerfish (Bohadschia argus), Surf Redfish (Actinopyga mauritiana), Hairy Blackfish (Actinopyga miliaris), Stonefish (Actinopyga lecanora), Prickly Redfish (Thelenota ananas) and Sandfish (Holothuria scabra). Length and weight recovery rates varied between species and ranged from the highest recovery values of 54.9% for length and 11% for weight in Black Teatfish, to the lowest recovery values of 32.6% for length and 3.0% for weight in Sandfish and Tigerfish, respectively. Length-based and weight-based relationships were generated for each species through the various stages of processing from fresh to dried (BDM) allowing estimation of initial fresh weight/length from partially or fully processed BDM and vice versa. Information generated in this study provides a basis for developing more species-specific harvest size restrictions for sea cucumbers in the Fiji Islands, and has application in stock assessment studies, estimation of harvest data, monitoring of harvest size limits and standardizing catch data.

Substrate preference for burying and feeding of sandfish Holothuria scabra juveniles

Substrate preference for both burying and feeding of sandfish Holothuria scabra juveniles (3–6g wet body weight) and their associated daily behavior, growth and survival were investigated in laboratory and field experiments using different coastal substrate types (silty mud, sandy mud, and coarse sand) to determine the ideal habitat for potential grow-out culture, sea ranching or stock enhancement of this important sea cucumber species. During the peak hours of burying (03:00–09:00h) and feeding (15:00–03:00h), a significantly greater number of sandfish juveniles preferred to bury in (28.3%) and feed on (21.5%) sandy mud, typical of intertidal coastal sand flats. Silty mud was the least preferred substrate for feeding (13.5%) and burying (13.8%). Burying and feeding preferences of sandfish juveniles were not significantly influenced by the presence of seagrass (Thalassia hemprichii) on coarse sand. Growth of sandfish juveniles in the first two weeks of rearing in tanks was significantly greater on coarse sand (growth rate: 0.59gd−1 or 7.0% d−1), followed by sandy mud (0.34g d−1 or 4.72% d−1) while OM content of these sediments remain almost unchanged. On silty mud, sandfish juveniles constantly shrunk (−0.02g d−1 or −0.63% d−1) for 8 weeks while sediment OM content increased. In the field, silty mud substrate of a mangrove pond caused total mortality of sandfish within two weeks, while sandy mud substrate of a sand flat provided significantly higher growth than the control (no sediment), but not significantly different than coarse sand of a seagrass bed. Sandy mud to coarse sand substrates of intertidal sand flats were most preferred by sandfish juveniles while silty mud associated with muddy mangroves and culture ponds seems to be unsuitable that sandfish would opt to avoid. Our results will contribute to the selection of suitable sites for sandfish sea ranching and stock enhancement in coastal areas.

MiR210 modulates respiratory burst in Apostichopus japonicus coelomocytes via targeting Toll-like receptor

Immune responses of species in Echinodermata remains mysterious due to the lack of efforts made in the study of host defense mechanism in these species. More researches start focusing on this ancient immune system with the recognition the economic values of several species in this phylum, especially sea cucumbers. Here, we reported a study in the innate immunity of a sea cucumber species (Apostichopus japonicus) in response to infection of Vibrio splendidus. A novel differential expressed miRNA (miR-210) from the diseased sea cucumber coelomocytes was identified in our study. This miRNA molecule modulates Toll-like receptor gene (AjToll) expression via binding 3′UTR region from 906 nt to 930 nt. Upon the challenge of V. splendidus, coelomocytes in A. japonicas demonstrated a upregulation of AjToll but a downregulation of miR-210. Transfection of miR-210 agomirs in coelomocytes significantly depressed the expression of AjToll in cells. As a result of AjToll expression inhibition by miR-210, the AjToll downstream molecules involved in reactive oxygen species (ROS) were also altered in vivo. This ROS pathway alternation was consistent with that caused by knockdown of AjToll through small inference RNA (siRNA). Taken together, the results of this study demonstrated a novel immune regulatory pathway via miRN-210 in A. japonica, which provides basic knowledge in exploring innate immunity of Echinodermata, and also can be reference in disease control in sea cucumber culture industry.

Interactions and accumulation differences of metal(loid)s in three sea cucumber species collected from the Northern Mediterranean Sea

This study was conducted on Holothuria polii, Holothuria tubulosa, and Holothuria mammata collected from five stations with different depths in the Northern Mediterranean Sea. The body walls and guts of these holothurians were examined in terms of interactions of 10 metals (iron (Fe), copper (Cu), manganese (Mn), zinc (Zn), chromium (Cr), cobalt (Co), vanadium (V), nickel (Ni), cadmium (Cd), and lead (Pb)) and one metalloid (arsenic (As)) using a multivariate analysis, and interspecies differences were determined. The multivariate analysis of variance (MANOVA) revealed significant differences between the species in terms of metal(loid) accumulations. The principal component analysis (PCA) showed a more association between H. tubulosa and H. polii with regard to the accumulation. The cluster analysis (CA) located Pb concentrations of the guts to the farthest place from all elements regardless of the species. A correlation analysis displayed that the element concentrations of the guts were more closely related to each other compared with those of the walls. The most inconsistent element in terms of correlations was the gut Fe contents. Accordingly, while Fe concentrations of H. mammata and H. tubulosa were correlated with all elements (except Pb) in divalent metal transporter 1 (DMT1) (divalent cation transporter 1 (DCT1) or natural resistance-associated macrophage protein 2 (NRAMP2)) belonging to the NRAM protein family, this was not the case in H. polii. Consequently, significant relationships between accumulated metal(loid)s that changed by tissues and sea cucumber species were observed.

Long Non-Coding RNAs (lncRNAs) of Sea Cucumber: Large-Scale Prediction, Expression Profiling, Non-Coding Network Construction, and lncRNA-microRNA-Gene Interaction Analysis of lncRNAs in Apostichopus japonicus and Holothuria glaberrima During LPS Challenge and Radial Organ Complex Regeneration.

Long non-coding RNA (lncRNA) structurally resembles mRNA but cannot be translated into protein. Although the systematic identification and characterization of lncRNAs have been increasingly reported in model species, information concerning non-model species is still lacking. Here, we report the first systematic identification and characterization of lncRNAs in two sea cucumber species: (1) Apostichopus japonicus during lipopolysaccharide (LPS) challenge and in heathy tissues and (2) Holothuria glaberrima during radial organ complex regeneration, using RNA-seq datasets and bioinformatics analysis. We identified A. japonicus and H. glaberrima lncRNAs that were differentially expressed during LPS challenge and radial organ complex regeneration, respectively. Notably, the predicted lncRNA-microRNA-gene trinities revealed that, in addition to targeting protein-coding transcripts, miRNAs might also target lncRNAs, thereby participating in a potential novel layer of regulatory interactions among non-coding RNA classes in echinoderms. Furthermore, the constructed coding-non-coding network implied the potential involvement of lncRNA-gene interactions during the regulation of several important genes (e.g., Toll-like receptor 1 [TLR1] and transglutaminase-1 [TGM1]) in response to LPS challenge and radial organ complex regeneration in sea cucumbers. Overall, this pioneer systematic identification, annotation, and characterization of lncRNAs in echinoderm pave the way for similar studies and future genetic, genomic, and evolutionary research in non-model species.

Role of deposit‐feeding sea cucumbers in integrated multitrophic aquaculture: progress, problems, potential and future challenges

AbstractThere is significant commercial and research interest in the application of sea cucumbers as nutrient recyclers and processors of particulate waste in polyculture or integrated multitrophic aquaculture (IMTA) systems. The following article reviews examples of existing IMTA systems operating with sea cucumbers, and details the role and effect of several sea cucumber species in experimental and pilot IMTA systems worldwide. Historical observations and quantification of impacts of sea cucumber deposit‐feeding and locomotion are examined, as is the development and testing of concepts for the application of sea cucumbers in sediment remediation and site recovery. The extension of applied IMTA systems is reported, from basic piloting through to economically viable farming systems operating at commercial scales. The near‐global recognition of the ecological and economic value of deposit‐feeding sea cucumbers in IMTA applications within existing and developing aquaculture industries is discussed. Predictions and recommendations are offered for optimal development of sea cucumber IMTA globally. Future directions within the industry are indicated, and key areas of ecological, biological and commercial concern are highlighted to be kept in mind and addressed in a precautionary manner as the industry develops.

Effectiveness of two tagging devices in the sea cucumber Holothuria (Halodeima) grisea

A reliable and harmless mark–recapture method provides valuable information for the management of commercial sea cucumber species. Nevertheless, marking and tracking sea cucumbers is notoriously difficult and represents a serious challenge. In this study, we tested one external and one internal tag in the sea cucumber Holothuria grisea. A passive integrated transponder (PIT) tag was inserted into the coelomic cavity in one treatment, whereas a T-bar (external tag) was attached in the upper surface of the body wall in the other treatment; sea cucumbers were then followed for 17 weeks. The tagging procedure caused no evisceration in the experimental groups, nor was a significant difference in growth rate found between treatments. The retention of the PIT tag was low, with 100% lost by Week 9. Retention of T-bars was higher, with 90% still attached by the end of the Week 8, but retention decreased thereafter as T-bar absorption increased. No relationship was found between initial weight and the number of weeks PIT tags (r=–0.173, P=0.781) or T-bars (r=–0.220, P=0.652) were retained. Neither the T-bar nor the PIT tags fulfilled the requirements of high retention required for long-term studies. However, we do recommend the use of T-bars for short-term studies for H. grisea under laboratory conditions or in a habitat with low substrate complexity.