Ecological effects of co-culturing the sea cucumber <Emphasis Type="Italic">Apostichopus japonicus</Emphasis> with the Chinese white shrimp <Emphasis Type="Italic">Fenneropenaeus chinensis</Emphasis> in an earthen pond

Using net enclosures in an earthen pond, we established three culture treatments with the sea cucumber Apostichopus japonicus and the Chinese white shrimp Fenneropenaeus chinensis: monoculture of sea cucumbers (C), monoculture of shrimp (S), and co-culture of the two species (CS). We measured levels of suspended particulate matter in the water column; total organic matter, total organic carbon, total nitrogen, and carbon/nitrogen ratios in both settling particles and the sediment; and chlorophyll a levels in the sediment. We then compared these variables between the three treatments. We also examined growth, survival, and yield of the two species in the different treatments. From June to September, the mean monthly suspended particulate matter sedimentation rates in the CS and S treatments were significantly (P<0.05) greater than those in the C treatment. From August to November, the mean monthly total organic matter, total organic carbon, total nitrogen, and chlorophyll a contents in the sediment in the CS and S treatments were significantly ( P <0.05) greater than those in the C treatment. Final wet weight, specific growth rate, survival rate, and total yield of sea cucumbers in co-culture were all significantly greater than those of sea cucumbers in monoculture. There were no significant differences among any of these variables for shrimp reared in the two systems. The bioturbation of the sediment and fecal production of the shrimp likely supplied natural food for the sea cucumbers. Co-culture of the two species is a viable option for increasing yield per unit area, maximizing use of the water body, and diversifying crop production.     

Ecological effects of co-culturing sea cucumber Apostichopus japonicus (Selenka) with scallop Chlamys farreri in earthen ponds

Monthly changes in sedimentation and sediment properties were studied for three different culture treatments: sea cucumber monoculture (Mc), sea cucumber and scallop polyculture (Ps-c) and scallop monoculture (Ms). Results indicated that the survival rate of sea cucumber was significantly higher in Ps-c cultures than in Mc cultures. Sea cucumber yield was 69.6% higher in Ps-c culture than in Mc culture. No significant differences in body weight and scallop shell length were found between Ps-c and Ms cultures. The mean sedimentation rate of total particulate matter (TPM) was 72.2 g/(m2 d) in Ps-c cultures, with a maximum of 119.7 g/(m2 d), which was markedly higher than that of Mc (mean value). Sedimentation rates of organic matter (OM), total organic carbon (TOC), total nitrogen (TN) and total phosphorus (TP) in Ps-c cultures were also significantly higher than those in Mc cultures. TOC and TN contents of sediment increased rapidly in the first 5 months in Ms cultures and remained at a high level. TOC and TN contents in Mc and Ps-c cultures decreased during sea cucumber feeding seasons and increased during sea cucumber dormancy periods (summer and winter). The study demonstrates that co-culture of sea cucumber and scallop in earthen ponds is an alternative way to alleviate nutrient loads and improve water quality in coastal aquaculture systems. Moreover, it provides the additional benefit of an increased sea cucumber yield.     

Effect of co-culture of Chinese shrimp (<Emphasis Type="Italic">Fenneropenaeus chinensis</Emphasis>) and sea cucumber (<Emphasis Type="Italic">Apostichopus japonicus</Emphasis> Selenka) on pond environment

Monoculture of sea cucumber (pond S) and polyculture of shrimp with sea cucumber (pond SS) were established to evaluate the effect of shrimp on the environmental conditions of sea cucumber farming pond. Contributions of sediment organic matter (SOM2) resuspended from benthic sediment and the suspended particulate organic matter (SPOM) deposited from the water column to the precipitated organic matter (SOM1) collected with sediment traps were estimated with carbon stable isotope analysis. The results showed that the levels of SPOM and SOM2 in pond SS significantly decreased in comparison with those in pond S at the end of experiment (P < 0.05), indicating that co-culturing shrimp in sea cucumber farming pond could purify the farming water. Carbon stable isotope analysis showed that the proportion of SOM2 in SOM1 in pond SS (84.97% ± 0.38%) was significantly lower than that in pond S (95.20% ± 0.30%) (P < 0.05), suggesting that the resuspension of organic matter from benthic sediment into overlying water was reduced in polyculture pond. In contrast, the proportion of SPOM in SOM1 in pond SS (15.03% ± 0.38%) was significantly higher than that in pond S (4.80% ± 0.30%) (P < 0.05), indicating that the sedimentation of SPOM from water column was enhanced in pond SS owing to the biodeposition effect of shrimp.     

MOLAR RATIOS OF C, N, P OF PARTICULATE MATTER AND THEIR VERTICAL FLUXES IN THE YELLOW SEA

The vertical fluxes and molar ratios of carbon, nitrogen and phosphorus of suspended particulate matter in the Yellow Sea were studied based on the analysis of suspended particulate matter,sediments and sinking particles obtained by use of moored sediment traps. The POC ： PON ratios indicate that most of the particulate organic matter in the Yellow Sea water column comes from marine life rather than the continent. The vertical fluxes of SPM, POC, PON and POP in the Yellow Sea are much higher than those in other seas over the world, and present a typical pattern in shallow epicontinental seas. The estimated residence time of the bioactive elements showed that the speed of the biogeochemical process of materials in the Yellow Sea is much shorter than that in the open ocean as there was high primary productivity in this region.     

Application of Wet Waste from Shrimp (Litopenaeus vannamei) with or Without Sea Mud to Feeding Sea Cucumber (Stichopus monotuberculatus)

In the present study, the applicability of the wet waste collected from shrimp(Litopenaeus vannamei) to the culture of sea cucumber(Stichopus monotuberculatus) was determined. The effects of dietary wet shrimp waste on the survival, specific growth rate(SGR), fecal production rate(FPR), ammonia- and nitrite-nitrogen productions of sea cucumber were studied. The total organic matter(TOM) level in the feces of sea cucumber was compared with that in corresponding feeds. Diet C(50% wet shrimp waste and 50% sea mud mash) made sea cucumber grow faster than other diets. Sea cucumber fed with either diet D(25% wet shrimp waste and 75% sea mud mash) or sole sea mud exhibited negative growth. The average lowest total FPR of sea cucumber occurred in diet A(wet shrimp waste), and there was no significant difference in total FPR between diet C and diet E(sea mud mash)(P > 0.05). The average ammonia-nitrogen production of sea cucumber in different diet treatments decreased gradually with the decrease of crude protein content in different diets. The average highest nitrite-nitrogen production occurred in diet E treatment, and there was no significant difference in nitrite-nitrogen production among diet A, diet B(75% wet shrimp waste and 25% sea mud mash) and diet C treatments(P > 0.05). In each diet treatment, the total organic matter(TOM) level in feces decreased to different extent compared with that in corresponding feeds.     

COMPARATIVE STUDIES ON NITROGEN BUDGETS OF CLOSED SHRIMP POLYCULTURE SYSTEMS＂

April to October, 1997 comparative studios on the nitrogen budgets of closed shrimp polyculture systems showed that, in all the studied polyculture systems, nitrogen from feeds and fertilizers were the main input items, which comprised 70.7% - 83.9% of the total input nitrogen, 3.2% - 7.4% of which was provided by nitrogen fixation. It was in monoculture enclosures (Y-4, Y-11 and Y-12) that the percentage reached the maximum value. The output nitrogen in harvested products comprised 10.8% - 24.6% of total input nitrogen, and the highest percentage, 24.6%, was found in shrimp-fish-tagelus polyculture systems. In shrimp monoculture and shrimp-fish polyculture systems, they were 19.1% and 21.9%, respectively. The nitrogen utilization efficiency was different and varied from 12.2% to 20.1%. The highest, 20.1%, was found in shrimp-fish-tagelus polycultttre systems, and the average of 20.0% was found in shrimp-tagelus polyculture systems. The lowest, 12.2%, was found in shrimp monoculture systems.All the nitrogen utilization efficiencies in shrimp-fish systems or shrimp-scallop systems seemed to be higher than that of the monoculture system, but they showed little statistical difference. The main outputs of nitrngen were found in sediment mud, and comprised 48.2% -60.8% of the total input, the lowest percentage was found in shrimp-fish-tagelus polyculture systems, and the highost percentage in shrimp-scallop systems.During the experiment, nitrogen lost through denitrification and ammonia volatilization comprised 1.9% - 6.2%, averaged 2.8%, of the total input, and the loss through seepage comprised 5.9% - 8.9% of the total.The estimated nitrogen attached to the enclosure wall comprised 3.7% - 13.3% of the total, and was highest in shrimp monoculture systems. Compared with the classic shrimp farming industry, the closed shrimp polycul-ture systems may improve the nitrogen utilization efficiency, and hence reduce the environmental impacts on coastal waters. The nitrogen discharging rates for all the studied polyculture systems ranged from 3.0% to 6.0% of total input nitrogen.     

Carbon cycle in shrimp polyculture mesocosm

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节水型斑节对虾养殖池环境质量监测与评价

用质量指数法评价节水型斑节对虾养殖池的环境质量.将对照池海水平均质量指数与微生物调控的试验池比较,硫化物、DO、磷酸盐、COD分别高71%、43%、24%、8.3%,但非离子氨、无机氮分别低229%、122%.综合来看,试验池的水质优于对照池,对照池水质有轻微污染,污染因子是磷酸盐、COD、BOD;底质环境未受有机物和硫化物的污染,对照池有机物含量高于试验池,对照池硫化物含量低于试验池.     

A new method for the estimation of fine-sediment resuspension ratios in estuaries-taking the turbidity maximum zone of the Changjiang(Yangtze) estuary as an example

Based on the principle of conservative matter removal in estuary,a new method is proposed for estimating the ratio of sediment resuspension in estuaries with fine suspended sediments in the turbidity maximum zone(TMZ) of the Changjiang(Yangtze) estuary during 2005.Results show that there was a range of 18.7%±27.9% to 73.9%±22.5% per annum of total suspended particulate matter(SPM),with an average of 49.2%.Nearly half of the particulate matter in the TMZ originates from sediment resuspension.This indicates that sediment resuspension is one of the major mechanisms involved in formation of the TMZ.Compared with traditional method for calculating these ratios in the estuary,this new method evaluates the dynamic variation of SPM content carried by river runoff from the river mouth to the ocean.The new method produced more reliable results than the traditional one and could produce a better estimation of resuspension flux for particulate matter in estuaries.     

Variations of the suspended matter and the particulate organic carbon in the entry of the Gironde Estuary,France

The effects of using different types of glass fiber filters (GF/F, GF/C) and of sample treatments were evaluated. Studies on the variation of suspended matter (SM) and particulate organic carbon (POC) showed that: 1) the transversal and day to night variations are important and must be taken into account in order to get a correct river flux; 2) no regular seasonal variations of SM and POC were observed, as they are controlled essentially by the climatological, hydrologic, physiochemical, biological, and geological conditions of the drainage area. Contribution No 2246 from the Institute of Oceanology, Chinese Academy of Sciences.     

Production of Pacific White Shrimp Polycultured with Swimming Crab at Different Densities,and Nutrient Budget in the Enclosure System

This study was to evaluate the effect of stocking densities on the nitrogen and phosphorus budgets for a polyculture of the crab Portunus trituberculatus and the Pacific white shrimp Litopenaeus vannamei.The shrimps(initial weight,0.012 g)were cultured at a density of 45 shrimp m^-2,and juvenile crabs(initial weight,0.024 g)were cultured at five densities of 0,3,6,9,and 12 crabs m^-2.The treatments were grouped as C0S45,C3S45,C6S45,C9S45,and C12S45,respectively.Water quality parameters,growth of shrimp and crabs,and nitrogen and phosphorus budget were measured.The results indicated that the shrimp performances in polyculture treatments C3S45 and C6S45 were superior to those in the crab-free treatment(C0S45).The crab in treatments C3S45 and C6S45 exhibited a significantly higher final mean weight and carapace width/length than those in treatments C9S45 and C12S45.The final size and survival of crabs had a negative correlation with the increasing crab stocking density.The contents of total phos-phorus and total nitrogen and the comprehensive contamination index values were higher in the C9S45 and C12S45 treatments than in the other treatments.The conversion ratios of nitrogen for crab and shrimp growth in treatment C3S45 were significantly higher than those in the crab-free treatment.These findings indicate that polyculturing shrimp with crabs at suitable densities can improve productivity,profitability,nutrient utilization,and the environmental quality.From the 60-day treatments,the optimal culture densi-ties were 3-6 crabs m^-2 and 45 shrimps m^-2.     

Tempo-spatial variations of sediment-associated nutrients and contaminants in the Ruxi tributary of the Three Gorges Reservoir,China

Ruxi River is a tributary of the Three Gorges Reservoir. This study examined the temporal and spatial dynamics in particle size characteristics and the associated nutrients and contaminants of the fluvial suspended and deposited sediments along the Ruxi River. Temporal variations in the particle size distribution of the suspended sediment are controlled mainly by differences in sediment source during different seasons. Total organic carbon(TOC), total nitrogen(TN) and total phosphorous(TP) in the 62μm fraction of the suspended sediment exhibit considerably higher concentrations in spring,indicating high probability of algal blooms in the backwater areas. Downstream trends in the nutrient contents of 62 μm deposited sediments imply the greatest potential for eutrophication in the backwater ends, where highest nutrient concentrations were detected. Assessment of metal contamination shows that the sediments deposited in the water-level fluctuation zone were moderately to strongly contaminated by Cadmium(Cd), with a considerably high potential ecological risk. The findings reported have emphasized the impacts of reservoir impoundment on aquatic and/or terrestrial environment in this region. More information on physical, chemical and biological processes of sediment and sediment-associated materials are needed for developing environmentally and ecologically sound policies of water and sediment management.     

VARIATIONS OF THE SUSPENDED MATTER AND THE PARTICULATE ORGANIC CARBON IN THE ENTRY OF THE GIRONDE ESTUARY, FRANCE

The effects of using different types of glass fiber filters (GF/F, GF/C) and of sample treatments evaluated. Studies on the variation of suspended matter (SM) and particulate organic carbon (POC) showed that: 1) the transversal and day to night variations are important and must be taken into account in order to get a corrcet river flux; 2) no regular seasonal variations of SM and POC observed, as they are controlled essentially by the climatological, hydrologic, physiochernical, biological, and geological conditions of the drainage area.     

Seasonal variations of riverine organic carbon contents in Makou and Hekou gauge stations of the Zhujiang River, China

Water samples were collected and analyzed in high water season (July 1997) and in middle water season (October, 1997) from two main lower reach gauge stations of the Zhujiang (Pearl) River, namely Hekou and Makou, respectively. Content of particulate organic carbon is always higher than that of dissolved organic carbon in both seasons, which is obviously different from the global average pattern, i.e. dissolved organic carbon is the dominant component of the transported riverine organic carbon. The content of dissolved and particulate organic carbon changes with the water levels in a direct ratio. The percentage of organic carbon in total suspended substance changes with the content of total suspended substance in an inverse ratio. The more intense is the soil erosion in the drainage, the more concentrated is the riverine organic carbon in the river. The contribution of autochthonous organic carbon is large in high water season than in middle water season. Fundation item: This project was supported financially by the National Natural Science Foundation of China (No. 49901002), the key funds of resources and eco-environmental research of the CAS (No. KZ952-J1-402), a funds of the state key laboratory of organic geochemistry, and Guangdong Province Science Funds (No. 984131). Biography: Gao Quan-zhou (1965 —), male, a native of Anhui Province, associate professor. His research interests are geomorphology and Quaternary geochemistry.     

Study on suspended matter in seawater in the Southern Yellow Sea

Distribution of suspended matter in seawater in the Southern Yellow Sea is investigated in five regions: 1) the Northern Jiangsu bank, the highest TSM (total suspended matter) content region; 2) the high TSM content region off the Changjiang River mouth; 3) the high TSM content region off the Chengshan Cape; 4) the low TSM region off Haizhou Bay; 5) the central part of the Southern Yellow Sea, a low TSM content region. The vertical distribution of TSM is mainly characterized by a spring layer of suspended matter, written as “suspended-cline” whose genesis is related to storms in winter. In this paper, non-combustible components and grain sizes in suspended matter, relationship between suspended matter and bottom sediments, and salinity in seawater are described. Investigation result shows that, in this area, suspended matter comes mainly from resuspended bottom sediment and secondarily from present discharge loads from rivers and biogenic materials. Discharged sediments from the Huanghe River move around the Chengshan Cape and affect the northwestern region of this area. Sediments from the Changjiang River affect only the southern part and have little or no direct influence on the central deep region. Wave is the main factor affecting distribution of suspended matter. Water depth controls the critical depth acted on by waves. The cold water mass in the central region limits horizontal and vertical dispersions of terrigenous materials. Suspended matter here has the transitional properties of the epicontinental sea. Its concentration and composition are different from those of a semi-closed sea (such as the Bohai Sea) and those of the East China Sea outer continental shelf or those near oceanic areas.     

Chronology and nutrients change in recent sediment of Taihu Lake,lower Changjiang River Basin,east China

Two short sediment cores named ZS and THS dated by the 210Pb or 137Cs method were collected from the northwest and southwest of Taihu Lake respectivly,and total organic carbon(TOC) and nutrients including total nitrogen(TN) and total phosphorus(TP) were determined to analyze the chronology and nutrients change in recent sediment.The results show that 137Cs activities are low(less than 15 Bq/kg) in the two cores,attributed to the 137Cs migration.Based on 210Pb constant rate of supply(CRS) model,the sedimentation accumulation rates range from 0.13 g/(cm2·yr) to 0.76 g/(cm2·yr) in the ZS core,and from 0.10 g/(cm2·yr) to 0.56 g/(cm2·yr) in the THS core.A remarkable increase in organic matter and nutrients has occurred in the two dated cores since the mid-1980s.The historical changes of organic matter and nutrients in the two cores are consisitent with the monitoring data for surface sediment after the 1960s.The TP accumulation rates after the early 1980s are 0.97 and 0.92 times higher than those from the 1950s to the 1980s in ZS and THS cores,respectively.Higher TP concentrations in the past two-decade deposits of Taihu Lake are due to both diagenetic factors and human activities.     

Soil organic carbon pool along different altitudinal level in the Sygera Mountains,Tibetan Plateau

Labile organic carbon (LOC) is one of the most important indicators of soil organic matter quality and dynamics elevation and plays important function in the Tibetan Plateau climate. However, it is unknown what the sources and causes of LOC contamination are. In this study, soil organic carbon (SOC), total nitrogen (TN), microbial biomass carbon (MBC), microbial biomass nitrogen (MBN) and LOC were analyzed based on different soil horizons and elevations using turnover time in an experimental site (3700 m to 4300 m area) in Sygera. SOC and LOC in higher-elevation vegetation types were higher than that of in lower-elevation vegetation types. Our results presented that the soil microbial biomass carbon (SMBC) and soil microbial biomass nitrogen (SMBN) were positively correlated with SOC. The content of easily oxidized carbon (EOC), particulate organic carbon (POC) and light fraction organic carbon (LFOC) decreased with depth increasing and the content were the lowest in the 60 cm to 100 cm depth. The total SOC, ROC and POC contents decreased with increasing soil horizons. The SOC, TN, MBC and MBN contents increased with increasing altitude in the Sygera Mountains. The MBC and MBN contents were different with the changes of SOC (p<0.05), meanwhile, both LFOC and POC were related to total SOC (p<0.05). The physical and chemical properties of soil, including temperature, humidity, and altitude, were involved in the regulation of SOC, TN, MBC, MBN and LFOC contents in the Sygera Mountains, Tibetan Plateau.     

Behavior of different phosphorus species in suspended particulate matter in the Changjiang estuary

Suspended particulate matter (SPM) collected in the Changjiang (Yangtze River) estuary in June 2006 was separated into five fractions via water elutriation: clay-very fine silt (<8 μm), fine silt (8–16 μm), medium silt (16–32 μm), coarse silt (32-63 μm) and sand (>63 μm). The SPM and fractionated particles were sequentially analyzed by a modified SEDEX sequential extraction method to obtain six species of phosphorus: exchangeable or loosely-sorbed P, organic P, Fe-bound P, authigenic P, detrital P and refractory P. The results indicated that all particulate phosphorus species except for detrital P were negatively correlated to particle size; a high detrital P content was found in coarse silt and very coarse silt. From the inside of the river mouth to the gate of the river mouth, organic P, Fe-bound P and refractory P in the suspended particles decreased and a higher amount of exchangeable P appeared around the gate of the river mouth. From the gate of the river mouth to the sea, exchangeable P and organic P in suspended particles increased distinctly. The total particulate P flux into the estuary from the Changjiang River was about 45.45×10⁸ μmol/s during sampling. Of this, about 8.27×10⁸ μmol/s was associated with the “truly suspended” fraction. The bio-available particulate P flux was about 13.58×10⁸ μmol/s. Of this, about 4.24×10⁸ μmol/s was transported by “truly suspended” particles.     

Geochemical characteristics of phosphorus near the Huanghe River estuary

INTRODUCTIONPhosphorus (P)isanimportantlimitingelementinglobaloceanicproductivity (Holland ,1 978) ,soknowledgeofPisakeytobetterunderstandingofthecyclingofcarbon ,nitrogen,sulfur,andothernu trientelements.Inasimplemassbalancemodel,thelevelofdissolvedPintheoceanisafunctionoftherateofinputviarivers,andtherateofoutputviadepositioninsediments.Inthepresentstudy,thefocusisontheriverinePinputbytheHuangheRiver (YellowRiver)totheBohaiSea,andespeciallyontheamountofPsolubilizedfromsolidphasesupo…     

Middle Holocene Organic Carbon and Biomarker Records from the South Yellow Sea: Relationship to the East Asian Monsoon

The East Asian monsoon system influences the sedimentation and transport of organic matter in East Asian marginal seas that is derived from both terrestrial and marine sources. In this study, we determined organic carbon (OC) isotope values, concentrations of marine biomarkers, and levels of OC and total nitrogen (TN) in core YSC-1 from the central South Yellow Sea (SYS). Our objectives were to trace the sources of OC and variations in palaeoproductivity since the middle Holocene, and their relationships with the East Asian monsoon system. The relative contributions of terrestrial versus marine organic matter in core sediments were estimated using a two-end-member mixing model of OC isotopes. Results show that marine organic matter has been the main sediment constituent since the middle Holocene. The variation of terrestrial organic carbon concentration (OCter) is similar to the EASM history. However, the variation of marine organic carbon concentration (OCmar) is opposite to that of the EASM curve, suggesting OCmar is distinctly influenced by terrestrial material input. Inputs of terrestrial nutrients into the SYS occur in the form of fluvial and aeolian dust, while concentrations of nutrients in surface water are derived mainly from bottom water via the Yellow Sea circulation system, which is controlled by the East Asian winter monsoon (EAWM). Variations in palaeoproductivity represented by marine organic matter and biomarker records are, in general, consistent with the recent EAWM intensity studies, thus, compared with EASM, EAWM may play the main role to control the marine productivity variations in the SYS.