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Studies on the Effects of Bio-deposition and Related Ecological Effects in Different Polyculture Mode of Sea Cucumber Apostichopus Japonicus (Selenka) Culture Pond

Author: RenZuoChao
Tutor: DongShuangLin
School: Ocean University of China
Course: Aquatic organisms
Keywords: Apostichopus japonicus Parastichopus californicus Integrated farming Pond water Sediment Participation artificial reef Artificial breeding Microalgae bait
CLC: S968.9
Type: PhD thesis
Year: 2012
Downloads: 4
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Abstract

In order to establish a muti-trophic integrated aquaculture system with sea cucumber, the sedimentation and ite related ecological effects in different sea cucumber co-culture ponds were investigatd. Especially, the water quality and primary production, particulate deposition and sediment characteristics in co-culture pond of sea cucumber with other organisms (e.g. scallop, jellyfish and shrimp), and the biochemical process on biofilm of sea cucubmer reef/substrates were estimated in field. The present study was targeted to make full use of the water space and the culture season, and help to establish methodologies for ingegrated muti-trophic aquaculture (IMTA). In order to develop new holothurian species for aquaculture, the present study first explored to rear red giant sea cucumber Parastichopus californicus in the hatchery. We conducted a series of experiments to figure out the effects of exogenous factors (e.g. quatity and quality of microalgal diets, larval stocking density and diet ration, temperature) to the growth, survival and metamorphosis for larval P. californicus. The results obtained in the present study will obviously help to establish protocols for the hatchery-rearing of P. californicus in near future.1. Water quality in sea cucumber culture pondIn the present study, the structure and biomass of phytoplankton community and the changes of chlorophyll content and primary production were assessed in the water and sediment, respectively. There62species in44generas belonging to seven phylum of phytoplankton were identified during the experiment, and it indicated that the phytoplankton in the present study were dominated by diatoms in sea cucumber pond. The dinoflagellate concentration in the water was higher during summer time. The sediment content of chlorophyll and pheophytin reached the maximum during sea cucumber aestivation period. The results indicated that the water of sea cucumber culture pond had lower biomass of phytoplankton but higher diversity index. It is suggested to improve the primary production level and the accelerate sedimentation rate with the purpose to supply more natural food resource and energy for the sea cucumber pond.2. Bio-deposition, re-suspension and sediment properties in sea cucumber monoculture pondSedimentation of total particulate matter (TPM) and sediment chemical change (carbon, nitrogen and phosphorous) were first examined in sea cucumber monoculture pond. The results showed that the sinking particles in the sea cucumber culture pond are origined from exogenous input, newly born in the water and resuspension of the sediment. The sedimentation rate of TPM in the pond water was25.4g/m2d, in which sedimentation rate of total organic carbon (TOC), total nitrogen (TN) and total phosphorous (TP) was925.7mg/(m2·d),66.8mg/(m2-d) and25.0mg/(m2·d), respectively. Sedimentation rate of chlorophyll and pheophytin in the sinking particles was913.9μg/(m2·d) and1139.1p.g/(m2·d), respectively. The resuspension rate of sinking particles in the pond reached75-94%. Resuspension rate of sinking particles was higher in spring and autumn than those in summer and winter. The mean sediment content of TOC, TN, TP, chlorophyll and pheophytin was2.6mg/g,1.3mg/g,1.0mg/g,1.0μg/g and4.6μg/g, respectively.3. Benthic-pelagic couplings and the their effects to sea cucumber in different co-culture systemIntegtated aquaculture plays important role in modern aquaculture industry. The present study investigated bio-deposition and its effects to the sediment in three different polyculture systems, i.e., sea cucumger polyculture with scallop, sea cucumber polyculture with shrimp and sea cucumber polyculture with jellyfish. The results showed that the mean TPM sedimentation rate in sea cucumber and scallop polyculture system was70.1g/m2d, the maximal reaching119.7g/m2d, and mean sedimentation rate of TPM in sea cucumber and jellyfish polyculture system was75.6g/m2d. TPM sedimentation rate in sea cucumber and shrimp polyculture system was ranged from21.6to57.7g/m2d. The sedimentation rates of TPM, TOC, TN and TP in sea cucubmer polyculture system were all higher than those in sea cucumber monoculture system (P<0.05). The faeces and pseudofaeces produced by scallop termed as biodeposites as a result of filter feeding effect accelerated sedimentation of total particles from the water layer to the bottom. Jellyfish was able to transfer the productivity from the water to the bottom more efficiently. The activity of Chinese shrimp at the bottom could cause the resuspension of benthic sediment, accelerate the inorganic matter back to the water, meanwhile, shrimp excretion would fertilize the mud sediment which increased benthic diatoms biomass. The co-culture significantly increased the organic matter in the sediment supporting higher growth and suvival rate of sea cucubmer. Meanwhile, sea cucubmer feeding had the potential to alleviate hight nutrition loadings at the pond bottom.4. Biofilm on the sea cucubmer reefs and its ecological effectThe artificial reefs are widely used in sea cucumber aquaculture industry to supply habitat for sea cucubmer. The present study investigated the ecological effects of artificial reefs. The results showed that the biomass and diversity of benthic animals were liigher in spring than in autumn. The benthic animals were mainly assemblaged in the gap of reefs, indicating the reefs supply shelters for sea cucumber. The aggregates of organic detritus and benthic diatoms on the reef supplied food source for sea cucumber. The Chi α/Pheophytin ratio of particulate matter on the reef was greater than1in spring period which indicated more living microalga, however, the ratio of Chl a/Pheo of particulate matter on the reef was lower than1in autumn indicating more degraded matter. The artificial reefs in pond acted as shelters for sea cucumbers and the biofilm on the reef contained high nutrition. Furture, the biofilm increased the bottom area of pond inhancing the stablity of the culture system, and absorb more nutrition from the water. The sedimentation in the water of different culture mode were significantly different, and it might cause different nutrition content on reef.5. Integrated aquaculture with sea cucumberIn order to make full use of the water source in sea cucumber culture pond, a new integrated culture mode of spatialformula and staggeredform were established. In the integrated culture mode, the juvenile sea cucumber was released to the pond in spring, juvenile shrimp and jellyfish are stocked in summer time when the sea cucumber being in aestivation, after the shrimp and jellyfish being harvested, scallop were hanged-culture in pond until next spring. The results showed that the newly designed integrated aquaculture system was able to yield more sea cucumber product. Further, we obtained extra cash crop by harvesting the commercial product of scallop, shrimp and jellyfish. Sea cucumber feeding on the biodeposits effectively alleviated organic loading in the seidment.6. Effects of exogenous factors to the growth, survival and metamorphosis of Parastichopus californicusThe body length, survival, and metamorphosis of auricularia larval Parastichopus californicus were tested respectively by feeding eight single species of microalgal diets, following the single diet trial, five superior single species were selected and mixed in binary to test the "synergistic" or "non-additive" effect to the growth, survival and metamorphosis of larval P. californicus. In single diet trial, the mono-species of Cc provided a superior diet for P. californicus larvae, yielding a survival rate of72.3%and the highest metamorphic rate of62.8%. Single3H and Ts contain really poor food value diet for P. californicus larvae, resulting in the lowest survival rate of59.3%and55.7%, final body length of681.8-μm and714.0-μm, and metamorphic rate of0.5%and0.7%, respectively. The microalgal mixtures with Cc showed no significant (P<0.05) differences in metamorphic rate compared with

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