Sea Cucumber Australostichopus Research Articles

Physicochemical Properties, Functionalities, and Antioxidant Activity of Protein Extracts from New Zealand Wild Sea Cucumbers (Australostichopus mollis).

This study investigated the physicochemical properties, functionalities, and antioxidant capacities of protein extracts from wild sea cucumber Australostichopus mollis collected from four distinct locations in New Zealand. Protein was extracted from sea cucumber body walls using trypsin enzymatic extraction, followed by cold acetone precipitation. The amino acid analysis revealed high glycine (189.08 mg/g), glutamic acid (119.45 mg/g), and aspartic acid (91.91 mg/g) concentrations in all samples. The essential amino acid indexes of the protein extracts (62.96, average) were higher than the WHO/FAO standard references, indicating the excellent protein quality of A. mollis. Furthermore, protein extracts from A. mollis demonstrated superior emulsifying activity (202.3-349.5 m2/g average) compared to commercial soy and whey protein isolates under all tested pH conditions, and enhanced foaming capacity (109.9-126.4%) and stability (52.7-72%) in neutral and acidic conditions. The extracts also exhibited good solubility, exceeding 70% across pH 3-11. Antioxidant capacities (ABTS and DPPH free radical scavenging activity and ferric reducing antioxidant power) were identified in A. mollis protein extracts for the first time, with clear variations observed among different locations. These findings elucidate the advantageous functional properties of protein extracts from wild New Zealand A. mollis and highlight their potential application as high-quality antioxidant food ingredients.

Maternal investment and nutrient utilization during early larval development of the sea cucumber Australostichopus mollis

Echinoderms are widely used to investigate the relationship between egg size, energy content and larval developmental strategies in marine invertebrates; although there have been few studies on ophiuroids and holothuroids. In this paper, we provide the first detailed biochemical information on egg composition and utilization in the planktotrophic holothuroid, Australostichopus mollis. The egg ultrastructure, protein content (85.1 ng egg−1) and lipid:protein ratio of 0.42 were consistent with those of other planktotrophic echinoderms of similar egg size. However, the lipid content (35.6 ng egg−1) was outside the 95% prediction band for the relationship between egg size and lipid content for echinoderms. Triacylglycerol (TAG) was the main energetic lipid present in the egg, with ca 50% of the TAG being utilized to construct the feeding auricularia; the remaining TAG was estimated to be consumed over 114.8 h (4.8 days) of development. Feeding a microalgal diet during early larval development did not affect the rate of TAG utilization, but increased protein content in the 90-h auricularia. Biochemical information from A. mollis eggs/larvae suggests that TAG might be the ancestral maternally derived energetic lipid in the Echinodermata, but also that there may be different patterns of lipid utilization between different classes.

Biochemical composition of the Australasian sea cucumber, Australostichopus mollis, from a nutritional point of view

BackgroundSea cucumbers are highly prized seafood in Asia, where the demand for them has increased dramatically in recent years. However, nutritional information is only available for only a few of the commercially traded species.MethodsIn this study, the biochemical composition of the sea cucumber Australostichopus mollis was evaluated in terms of the major functional components: collagen, amino acid and fatty acid content using standard analytical procedures.ResultsThe collagen, mostly type I, formed a homogeneously clustered network constituting 1.4% of the wet weight of adult A. mollis which is lower than for some other species of sea cucumber. The collagen consisted of α1 and α2 chains (around 116 kDa), α chain dimers, β chains (around 212 kDa), and small amounts of γ components. The most abundant amino acids were glycine, alanine, threonine, serine and proline (lysine/arginine ratio of 0.1). Threonine was the most abundant essential amino acid, followed by methionine and valine, while glycine was the dominant non-essential amino acid. The sea cucumbers had a low lipid content (0.2 and 0.1% of wet weight for the viscera and body wall, respectively) which is below the range reported for most other species of sea cucumber. The lipid contained high levels of PUFA (54%) compared to MUFA (23%) and SFA (24%). The dominant PUFA was arachidonic acid in both the body wall and viscera, followed by eicosapentaenoic acid.ConclusionsOverall, the Australasian sea cucumber has strong potential as a functional food due to its high levels of PUFA and essential amino acids, comparing favourably with the most commercially valuable sea cucumbers.

Effects of waterborne cadmium on energy metabolism in the tropical sea cucumber, Stichopus horrens, and a comparison of tissue-specific cadmium accumulation with the temperate sea cucumber Australostichopus mollis

The sea cucumber Stichopus horrens is an important component of near-shore ecosystems, and in the Kingdom of Tonga it also comprises an important commercial and subsistence fishery. To assess the sensitivity of this species to the toxic trace metal cadmium (Cd), adult S. horrens were exposed for 96h to an environmental (15µgL−1) or effect (765µgL−1) concentration of waterborne Cd. The respiratory tree and intestine accumulated higher concentrations of Cd than the muscle and body wall, but there were no effects of Cd on tissue ions (sodium, potassium, magnesium, calcium). For comparison, Cd accumulation was also examined in the Australasian sea cucumber Australostichopus mollis. This species displayed a similar pattern of tissue-specific accumulation to S. horrens, but exhibited lower tissue Cd burdens, likely a consequence of lower experimental temperature. Effects on gonad ion content were also seen in this species. At the highest Cd exposure concentration, S. horrens showed impaired ammonia excretion rates and an increased molar oxygen:nitrogen ratio (O:N), indicative of a decreased reliance on protein metabolism. Overall, this study suggests that S. horrens is relatively tolerant of Cd exposure, but raises concerns regarding the subsistence fishery practice of consuming the viscera of this species.

Low coverage sequencing of three echinoderm genomes: the brittle star Ophionereis fasciata, the sea star Patiriella regularis, and the sea cucumber Australostichopus mollis

BackgroundThere are five major extant groups of Echinodermata: Crinoidea (feather stars and sea lillies), Ophiuroidea (brittle stars and basket stars), Asteroidea (sea stars), Echinoidea (sea urchins, sea biscuits, and sand dollars), and Holothuroidea (sea cucumbers). These animals are known for their pentaradial symmetry as adults, unique water vascular system, mutable collagenous tissues, and endoskeletons of high magnesium calcite. To our knowledge, the only echinoderm species with a genome sequence available to date is Strongylocentrotus pupuratus (Echinoidea). The availability of additional echinoderm genome sequences is crucial for understanding the biology of these animals.FindingsHere we present assembled draft genomes of the brittle star Ophionereis fasciata, the sea star Patiriella regularis, and the sea cucumber Australostichopus mollis from Illumina sequence data with coverages of 12.5x, 22.5x, and 21.4x, respectively.ConclusionsThese data provide a resource for mining gene superfamilies, identifying non-coding RNAs, confirming gene losses, and designing experimental constructs. They will be important comparative resources for future genomic studies in echinoderms.Electronic supplementary materialThe online version of this article (doi:10.1186/s13742-016-0125-6) contains supplementary material, which is available to authorized users.

Stereo‐imaging AUV detects trends in sea urchin abundance on deep overgrazed reefs

AbstractRemote underwater vehicles are cutting‐edge tools for mapping benthic habitats, yet their reliability for detecting patterns in abundance of benthic species remains largely unexplored. Here, we use a stereo‐imaging AUV to investigate changes in abundance of the overgrazing sea urchin, Centrostephanus rodgersii, which has undergone climate driven range‐extension to Tasmania. As part of ongoing bi‐yearly monitoring of urchin impacts (June 2009–2013), the benthic stereo‐imaging AUV (Sirius) surveyed fixed geo‐referenced 25 × 25 m plots (625 m2) on deep “urchin barrens” (25–30 m depth) and shallow barren/kelp transition zones (8–16 m) at two sites at St. Helens, northeast Tasmania (−41.25; 148.34). Coincident with initial AUV deployments, urchin abundance was also estimated in the same reef plots using conventional SCUBA diver belt‐transects; with comparison of AUV and diver sampling showing AUV‐derived estimates to be ∼ 40% lower; while additional AUV sampling at night (high risk for divers in deep water) detected abundances only ∼16% lower than that measured by daytime divers, demonstrating strong nocturnal emergence of C. rodgersii. Importantly, patterns in C. rodgersii abundance across reefs and depths were similar between methods; and long‐term population trends were concordant between diver and AUV methods. At finer‐scales, AUV detections were compromised where remnant kelp canopies obscured urchins, indicating divers to be superior for detecting early‐warning of population increases within intact kelp beds. Comparison of C. rodgersii with two other macro‐invertebrates (sea cucumber Australostichopus mollis and sea urchin Heliocidaris erythrogramma) revealed that while stereo‐imaging AUVs can detect space/time variability in macro‐invertebrate abundance, detectability is highly dependent on local ecologies and species‐specific behaviours.

Macronutrient selection, absorption and energy budget of juveniles of the Australasian sea cucumber,Australostichopus mollis, feeding on mussel biodeposits at different temperatures

This study was set up to examine the selection and absorption of macronutrients (lipid, protein and carbohydrate) of juveniles of the Australasian sea cucumber Australostichopus mollis, feeding on an effective natural feed (mussel waste) at different temperatures. Our results indicate that the juveniles select and absorb lipid more efficiently than carbohydrate and protein at all temperatures. However, the overall magnitude of absorption of carbohydrate and protein make them the main source of nutritional energy for juvenile sea cucumbers. Seawater temperature affects the feeding behaviour of the juveniles, reducing the selection efficiency of macronutrients, while increasing metabolic energy demand, resulting in less energy available for growth. These results show the importance of each macronutrient in the diet of A. mollis as a source of energy for growth, which opens up the possibility to replace more expensive nutrient sources, such as protein and lipid, with less costly carbohydrate to reduce costs of diet formulation.

Patterns of distribution and abundance of the temperate sea cucumber Australostichopus mollis on a rocky subtidal reef

Temperate species of sea cucumber found on rocky subtidal reefs often have a patchy distribution. If rocky reef complexity is important to the temperate sea cucumber Australostichopus mollis then this should be correlated with relative differences in their abundance along the coast. These temperate subtidal rocky reefs present a variety of possible habitat types that can be patchy in their distribution along the coast. Subtidal surveys were conducted along a 2.5-km stretch of coast and counts of A. mollis recorded along with changes in the composition of a number of physical features of reef structure. Abundance of A. mollis decreased from 1 individual/2 m2 in headland outcrops to 1 individual/20 m2 and 1 individual/100 m2 for coastal areas and inner bays respectively. This was associated with a decrease in percentage composition of large boulders, which were between 0.5 and 1 m along their longest diameter and were part of a predominantly rock and boulder substrate. Where sea cucumber abundance decreased for identified location types there was also a corresponding decrease in kelp cover and an increase in open rock faces of a ridged or corrugated structure. Physical features of temperate reef structure, their contribution to overall reef complexity, and location along the coast, are determining factors mediating the distribution and abundance of A. mollis.

Sea cucumber habitat differentiation and site retention as determined by intraspecific stable isotope variation

Stable carbon and nitrogen isotope ratios (δ13C/δ15N) were assessed as a means to ascertain the recent in situ feeding history of the common New Zealand sea cucumber Australostichopus mollis in relation to nutrient enrichment from a longline green-lipped mussel (Perna canaliculus) farm in Northern New Zealand. δ13C and δ15N isotopic signatures and the ratios of sea cucumbers sampled from within the impact footprint of the mussel farm were compared with those of sea cucumbers residing on adjacent natural reefs. Sea cucumbers from beneath mussel farming longlines had significantly different δ13C stable isotope signatures in comparison with sea cucumbers collected from neighbouring natural reef habitats. This difference supports the hypothesis that sea cucumbers in the same bay maintain distinctly different feeding histories, with those residing beneath mussel farming longlines deriving tissue carbon from sediment impacted by farming activities. This hypothesis is further supported by the finding that the isotope signature of sediment collected from beneath the mussel farm is consistent with the expectation that sea cucumbers were feeding on and consuming sediment enriched with bivalve waste (faeces and pseudo-faeces). In contrast, the nitrogen stable isotope signature (δ15N) was found to be similar between sites for both sea cucumbers and assumed food sources. Both findings lend support to the viability of future sea cucumber/green-lipped mussel farm polyculture systems. Sea cucumbers in different locations (mussel farm, natural reef) possessed distinctly different isotope signatures, suggesting that mixing of sea ranched sea cucumbers with natural reef populations would be negligible or non-existent. Similarities between the isotope signatures in low metabolic tissue of sea cucumbers residing at the mussel farm site to that of mussel farm-impacted sediment suggest that cucumbers beneath mussel farms appear to have high rates of retention at the farm site.

Do benthic sediment characteristics explain the distribution of juveniles of the deposit-feeding sea cucumber Australostichopus mollis?

Despite the economic importance of many deposit-feeding sea cucumbers, the ecology of their juveniles is poorly understood and factors influencing juvenile habitat selection remain largely unexplained. We investigated the importance of the characteristics of the available sediment in determining the highly localised distribution of juveniles of the deposit-feeding Australasian sea cucumber Australostichopus mollis. Wild-caught juveniles were displaced to non-juvenile habitats with surface sediments characterised by lower total organic content (TOM) and nitrogen content, higher chlorophyll- a content and coarser grain size profiles compared to juvenile sites. The growth of displaced individual animals was monitored over 9 months and compared to control animals caged in the juvenile habitats. Displaced juvenile sea cucumbers had high survival rates that did not differ significantly from juvenile habitats. Displaced juveniles exhibited significantly higher specific growth rate (SGR) than those at juvenile sites ( p < 0.001), although the growth of individuals was highly variable within individual cages and among sites. The lower TOM and nitrogen content, and coarser grain size profiles at non-juvenile sites did not result in reductions in juvenile survival or growth. Higher microphytobenthic activity may have resulted in the higher growth rates observed at shallow non-juvenile sites. The SGR of juveniles over the first 6 months of the experiment ranged between 0.45% d − 1 and 0.74% d − 1 for all sites. This was followed by marked growth limitation between 6 and 9 months either as a result of increasing juvenile biomass in cages or seasonal growth limitation. A subsequent reduction in juvenile density resulted in markedly increased growth over the following 3 month period. Juvenile A. mollis show an ability to exploit a variety of benthic sediment food sources, indicating that their highly localised distribution is not due to differences in the food quality of sediments, but is more likely to be due to other localised effects, such as larval settlement or predation.

Effect of sea cucumber (Australostichopus mollis) grazing on coastal sediments impacted by mussel farm deposition

Deposit-feeding holothurians are important processors of surface sediments in many coastal marine systems. The present study examined the effect of grazing by the sea cucumber Australostichopus mollis on sediment impacted by green-lipped mussel biodeposits (faeces and pseudofaeces) from coastal aquaculture activities. Grazing effects were investigated in a series of tank-based feeding experiments conducted over 1, 2, 4 and 8 week periods. Sediment quality indicators routinely applied to determine the impacts of coastal aquaculture were used to evaluate sediment health from grazed and ungrazed sediments. Sea cucumber grazing resulted in reductions in total organic carbon, chlorophyll a and phaeopigment, as well as chlorophyll a/phaeopigment ratio of impacted sediments. These results demonstrate that sea cucumber grazing significantly reduces the accumulation of both organic carbon and phytopigments associated with biodeposition from mussel farms. Sea cucumber grazing offers a means of constraining or reversing the pollutive impacts of coastal bivalve aquaculture.

The use of the waste from green-lipped mussels as a food source for juvenile sea cucumber, Australostichopus mollis

Improved knowledge of juvenile feeding behaviour in the sea cucumber Australostichopus mollis is essential to assist in raising hatchery reared juveniles, however, the feeding, nutrition and early growth of juvenile A. mollis remains undocumented. The survival and growth of juvenile sea cucumbers (22 ± 4 g SD, n = 90) on artificial feeds was assessed over three months. A natural sediment diet was provided at two separate feeding rates (1 kg base and 35 g d − 1 ), fresh mussel farm waste was fed at three incremented feeding rates (140 g d − 1 , 70 g d − 1 and 35 g d − 1 ), and dried Sargassum polycystum was fed at a single feeding rate (35 g d − 1 ). Juvenile sea cucumbers fed the highest rate mussel waste diet exhibited the greatest ( P < 0.01) overall specific growth rate (SGR), increasing in weight by an average of 30% (± 7.7 SD) over three months. Natural sediment diets resulted in negative SGR, while the S. polycystum diet and lower feeding rates of mussel waste produced intermediate SGRs. The growth performance of the different diets was also reflected in morphometric parameters (mean gutted weight, body wall and muscle band thickness) in the experimentally raised juvenile sea cucumbers. The results show that fresh mussel waste is a suitable artificial diet for juvenile sea cucumbers if provided in sufficient quantities. The results also indicate that rapid growth can be expected among juvenile sea cucumbers cultured beneath mussel farms provided sea cucumber stocking rates are managed appropriately to ensure an adequate supply of mussel waste.

The effect of food availability on phenotypic plasticity in larvae of the temperate sea cucumber Australostichopus mollis

Phenotypic plasticity in response to food availability results in either the achievement of larval metamorphic competence or exposing larvae to a reduced probability for survival. Larvae of the temperate aspidochirote sea cucumber, Australostichopus mollis fed the diatom Chaetoceros muelleri grew best in 3000 cells ml - 1 day - 1 , reaching a maximum length of 896 ± 22.8 μm by day 12 (mean ± SE). When shape was quantified independent of growth and size larvae were consistently shorter and wider in 300 but became longer and narrower in 3000 cells ml - 1 day - 1 . They were also consistently shorter and narrower in 6000 than those in 600 cells ml - 1 day - 1 , which became longer and wider. In both 300 and 6000 gut shape did not change whereas in 600 and 3000 cells ml - 1 day - 1 the gut became more oval shaped. By day 12 most in 3000 cells ml - 1 day - 1 were late auricularia whereas development was delayed in other feeding regimes. Although by day 18 in all feeding regimes larvae had 2 hyaline spheres in the posterior folds of the ciliated band, only those fed 600 and 3000 cells ml - 1 day - 1 had more. Of the surviving larvae in these feeding regimes, most were competent, undergoing, or likely to complete metamorphosis. Phenotypic plasticity or a change in shape allows larvae to moderate growth and form in response to food availability but it may also act as a selection mechanism in determining the contribution of larvae to subsequent generations by delaying development.

Metamorphosis in larvae of the temperate sea cucumber Australositchopus mollis

Summary Holothurian larvae that feed on phytoplankton during development exhibit a dramatic metamorphosis involving extensive reorganisation of all larval tissue before adopting a benthic existence and assuming the juvenile form. During this process in the temperate sea cucumber Australostichopus mollis the combined axohydrocoel differentiated into the coelomic lining of the buccal podia and radii, both appearing early. Although podia primordia appeared shortly after, the podia themselves appeared later. This process appeared associated with differentiation of oral cavity tissue and formation of the water vascular ring canal. Oral cavity tissue was displaced temporarily but was not evidence of axial torsion. Tissue differentiation of the reorganised alimentary canal occurred post settlement and the mouth of the benthic juvenile opened well after settlement to initiate feeding. These larvae exhibit a variable and protracted transition to the benthic juvenile form rather than an abbreviated sequence of progressive anatomical events as in indirect non-feeding developers.

Survivorship and growth of the sea cucumber Australostichopus (Stichopus) mollis (Hutton 1872) in polyculture trials with green-lipped mussel farms

The suitability of the common New Zealand sea cucumber Australostichopus mollis to polyculture with green-lipped mussels was investigated in a six-month field study. Sea cucumbers were caged at three densities (2.5, 5 and 15 ind m−2) on the seabed beneath an operating mussel farm and survivorship and growth (weight change) monitored on a monthly basis. The sea cucumbers transplanted to below an operating farm showed excellent survivorship (91.7% overall) over the period of the study and exhibited growth at densities exceeding observed natural densities. Growth was density-dependent and at the highest densities appeared to be constrained by food limitation. A. mollis held at 2.5 and 5 ind m−2 gained 15.37%±5.33 (mean±SE) and 13.16%±3.42 of their pre-caged body weight, respectively, while those caged at a density of 15 ind m−2 showed a 0.21%±2.12 weight loss over the six-month trial. In addition, the acceptability of mussel farm-impacted sediment as a food source was investigated in tank-based feeding experiments with wild-collected A. mollis. Adult A. mollis readily consumed mussel farm-impacted sediment in laboratory feeding experiments, consuming 6.70 g±1.59 (mean±SE) wet weight mussel sediment d−1. These results clearly indicate that A. mollis is an ideal candidate for polyculture with green-lipped mussel farms.

A genetic linkage map for Atlantic halibut (Hippoglossus hippoglossus)

The suitability of the common New Zealand sea cucumber Australostichopus mollis to polyculture with green-lipped mussels was investigated in a six-month field study. Sea cucumbers were caged at three densities (2.5, 5 and 15 ind m− 2) on the seabed beneath an operating mussel farm and survivorship and growth (weight change) monitored on a monthly basis. The sea cucumbers transplanted to below an operating farm showed excellent survivorship (91.7% overall) over the period of the study and exhibited growth at densities exceeding observed natural densities. Growth was density-dependent and at the highest densities appeared to be constrained by food limitation. A. mollis held at 2.5 and 5 ind m− 2 gained 15.37% ± 5.33 (mean ± SE) and 13.16% ± 3.42 of their pre-caged body weight, respectively, while those caged at a density of 15 ind m− 2 showed a 0.21% ± 2.12 weight loss over the six-month trial. In addition, the acceptability of mussel farm-impacted sediment as a food source was investigated in tank-based feeding experiments with wild-collected A. mollis. Adult A. mollis readily consumed mussel farm-impacted sediment in laboratory feeding experiments, consuming 6.70 g ± 1.59 (mean ± SE) wet weight mussel sediment d− 1. These results clearly indicate that A. mollis is an ideal candidate for polyculture with green-lipped mussel farms.

Mollisosides A, B1, and B2: Minor Triterpene Glycosides from the New Zealand and South Australian Sea Cucumber Australostichopus mollis

Three new monosulfated triterpene glycosides, mollisosides A (2), B(1) (3), and B(2) (4), have been isolated from the sea cucumber Australostichopus mollis. Their structures were determined by NMR and mass spectra. The presence of sulfated glycosides in sea cucumbers belonging to the family Stichopodidae is uncommon.