夏季桑沟湾养殖水域有机碳的平面分布特征及其来源分析

根据2012年8月对桑沟湾养殖海域18个站位取得的溶解有机碳(DOC)、颗粒有机碳(POC)和叶绿素a(Chl-a)数据,基于不同区域的养殖特点,分析了DOC和POC的平面分布特征,并对POC的来源进行了初步探讨。结果表明,整个调查海域表层DOC的浓度范围为1.70～2.82mg/L,平均值为2.03mg/L,大致呈自西向东递减的趋势。表层POC的浓度范围为0.04～1.33mg/L,平均值为0.55mg/L,大致呈自南向北逐渐递增的趋势。网箱养殖区表层DOC和POC含量最高,其次为桑沟湾近岸海域,而海带养殖区最低,这表明有机碳的含量与养殖品种和模式有直接的关系。根据POC/Chl-a比值对POC来源进行初步分析,表明贝类养殖区、海带养殖区、贝藻混养区、桑沟湾近岸海域以及外海对照点的POC主要来自活的浮游植物,而网箱养殖区存在降解的有机物质。     

桑沟湾养殖海域无机氮营养盐的分布与行为

调查结果表明，桑沟湾ＩＮ的垂直分布均匀；该海域受人类频繁活动的影响，其平面分布和量值都有显著的季节性差异；ＮＯ３－Ｎ是该海域ＩＮ的主要存在形式。在海带养殖期间，ＩＮ和ＩＮ／ＩＰ比值始终处于低水平，其季节变异明显受到该湾初级生产水平的制约，故ＩＮ必然成为桑沟湾初级生产的限制因素，另外，海带养殖也加速了其养殖期间湾内水体中ＩＮ的物质循环速率。     

同安湾浮游动物数量的平面分布和季节变动

本文主要研究2000年同安湾浮游动物的种类组成和数量分布，并就其与环境因子的关系进行了初步探讨。结果表明，在同安湾共记录到浮游动物69种及12种浮游幼虫，以近岸低盐种类为主。浮游动物数量季节分布呈现春季高，冬、夏季居中，秋季最低的特点。种类数的季节分布与水温的季节变化一致。浮游动物数量与养殖贝类、浮游植物细胞数密切相关，并与浮游植物数量呈显著的正相关关系。同安湾浮游动物的数量与邻近养殖水域西海域的相当，比马銮湾的低。与历史资料比较，同安湾浮游动物的次级生产力水平比1995年的有所上升，但恢复得较慢。     

桑沟湾养殖海域营养盐时空分布特征及富营养化评价

根据2014年10月、2015年3月、5月和8月在桑沟湾养殖水域开展的海洋调查所获取的营养盐状况调查数据,分析了营养盐含量的季节变化和平面分布,并对该水域营养水平状况进行了评价.结果显示,该海域秋季溶解无机氮(DIN)含量明显高于其他三个季节.夏季NO2-N的平均含量最高,秋季NO3-N的平均含量最高,春季NH4-N的平均含量最高,冬季PO4-P的平均含量最高.与海水水质标准相比,各季节DIN总体水平均低于海水一类标准值,春季和夏季PO4-P总体水平低于海水一类标准值,秋季和冬季PO4-P总体水平则高于海水一类标准值.从平面分布看,春季DIN含量呈湾内低、湾外高的趋势,夏季和秋季呈湾内高、湾外低的趋势,冬季呈自湾内南部水域向北逐渐降低的趋势.春季和冬季PO4-P含量均呈自湾内中部水域向外逐渐下降的趋势,夏季呈自湾内中部水域向外逐渐上升的趋势;秋季则呈湾内高、湾外低的趋势.春季、夏季和冬季N/P比值均高于Redfield比值,无机磷相对缺乏,而秋季N/P比值与Redfield比值基本一致.根据潜在性富营养化评价模式,桑沟湾养殖海域四个季节的营养水平较低,均属贫营养水平.与20世纪八九十年代相比,桑沟湾浮游植物生长的主要限制性因素已由整体的氮限制转变为春、夏季磷限制为主.     

桑沟湾多元养殖生态模型研究：Ⅱ生态环境模拟与生源要素循环

运用桑沟湾多元养殖生态模型,模拟得到了桑沟湾浮游植物和无机氮营养盐的年变化规律、水平分布的季节变化。结果表明,浮游植物生物量和无机氮营养盐浓度存在明显的季节变化,养殖活动的季节性增大了二者的季节变化幅度;桑沟湾浮游植物和无机氮营养盐的分布受大面积海带和贝类养殖的影响;外海营养盐补充是桑沟湾内无机氮营养盐的主要来源。     

桑沟湾浮游植物生态特征

根据2003年8月～2005年5月桑沟湾4个航次调查结果，对该海区浮游植物的种类组成、数量分布和群落结构进行分析。结果表明，调查海域共检出浮游植物32属72种。其中，硅藻29属60种，占83.3%。甲藻3属12种，占16.7%。浮游植物数量的变动范围为5.0×10^4～3416.0×10^4cell/m^3，浮游植物数量均值的最高值出现在2003年8月，最低值出现在2005年5月。经多样性指数、丰富度指数、均匀度指数和单纯度指数分析，调查海域浮游植物的群落结构随季节变化明显，秋季的种类数、多样性明显高于春季。综合评价表明，桑沟湾海域浮游植物种类个体数量分布不均匀，生物多样性一般。     

桑沟湾浮游植物粒径结构及其与环境因子的关系

于2017年4、7、11月和2018年1月4个航次调查了桑沟湾浮游植物粒径结构的时空分布，并分析了粒径结构与主要环境因子的关系。结果显示，桑沟湾海域表、底层Chl-a浓度的年变化范围分别为0.74?3.27和0.81?3.66 µg/L，平均值分别为(1.90±1.28)和(2.01±1.29) µg/L，存在极显著的季节差异(P<0.01)和空间分布的不均匀性。从粒径结构来看，小型浮游植物是春季表、底层浮游植物的主要贡献者，贡献率分别为54.05%和58.08%，夏、秋和冬季均是微型浮游植物占优势地位。冬季和春季微微型浮游植物的贡献率较小，但夏季和秋季的贡献率显著增多，夏季表、底层贡献率分别达24.46%和20.70%；秋季表、底层贡献率分别达35.88%和40.77%。冗余分析(Redundancy analysis, RDA)结果表明，温度(T)是影响浮游植物粒径结构的主要环境因子。溶解氧(DO)对微微型浮游植物占总浮游植物的比例有显著影响；微型浮游植物所占比例受亚硝酸盐(NO2?)、铵盐(NH4?)等影响显著；小型浮游植物对总浮游植物的贡献主要受温度影响，呈正相关。研究结果为深入认识桑沟湾养殖生态系统浮游植物的粒径结构、准确评估滤食性贝类的养殖容量提供了基础数据。     

桑沟湾养殖海域的水环境特征

本文研究了桑沟湾养殖海域的水环境特征，并与１０年前的历史资料作了比较。该湾各种化学指标的垂直分布均匀；受大面积高密度养殖影响，该湾水动力状况与１０年前相比发生了明显变化，营养物质输送和海水自净能力降低；各种化学指标、初级生产力、营养状况及类型等平面分布和季节性变化都有更加显著的差异。在海带养殖期间，ＩＮ和ＩＮ／ＩＰ始终处于低水平，其季节变化明显受该湾初级生产力制约，故ＩＮ必然成为桑沟湾初级生产的限制因素。另外，海带养殖也加速了其养殖期间湾内水体中ＩＮ的物质循环速率。     

栉孔扇贝对春季桑沟湾颗粒有机物的摄食压力

由于养殖密度和产量较高，滤食性扇贝的养殖活动对海洋碳循环的影响引起人们的关注。不仅收获贝类能够从海域中移出大量的颗粒有机碳（particle organic carbon,POC），而且，在贝类养殖过程中（滤食、呼吸、排粪等生理活动）也对养殖海区的POC产生较大的影响。目前，国内、外学者就贻贝养殖的碳氮通量、虾夷扇贝的碳收支情况、生物沉降及其对底栖生物群落的影响、养殖贝类对浮游植物和悬浮颗粒物的摄食等方面进行了广泛的研究。但是，养殖栉孔扇贝对我国主要养殖海区桑沟湾POC的摄食压力未见报道。     

虾塘养殖水环境中氮磷营养盐的存在特征与行为

根据现场调查结果，讨论了虾塘养殖水环境中氮磷营养盐的存在特征与行为，在该水环境中，ＩＰ的季节变化相对平稳，而ＩＮ则在养殖中后期变化幅度较大，ＩＮ和ＩＰ的垂直分布均匀；ＩＮ的形态分布有显著的季节变化，且与开阔浅海不同，ＮＯ２Ｎ也成为ＩＮ的主要存在形态，ＩＮ与ＩＰ比值始终较低，且ＩＮ在虾养殖期间的大部分时间内都处于贫瘠水平，从而构成该养殖水环境中初级生产的限制因素，而相对较高密度的浮游植物，则是缩短该     

Effect of temperature and phytoplankton concentration of Partitioned Aquaculture System water on freshwater mussel filtration

The freshwater mussel Elliptio complanata was provided green algal‐dominated water from a Partitioned Aquaculture System (PAS) over a range of water temperatures (6.1–32.4 °C) and suspended particulate organic carbon (POC) concentrations (<1–32.2 mg C L^?1) to determine filtration rates as mg POC kg^?1 wet tissue weight h^?1. The lowest filtration rates were observed at lowest temperatures and POC concentrations while the highest rates were at intermediate temperatures and the highest POC levels. The predicted filtration rate (PFR) in response to water temperature and POC concentrations was as follows: ln PFR=1.4352+0.1192 POC+0.1399 T?0.0001 T³. Within the experimental conditions, PFRs at any POC concentration increased with increased water temperature to a peak at 22 °C and then decreased. The maximum PFR occurred at 22 °C and 32 mg C L^?1 and the minimum PFR at 7 °C and 1 mg C L^?1. A model to describe the mussel filtration rate responses to PAS water conditions involves both water temperature and POC concentration.     

对虾池生态系统溶解有机碳及颗粒有机碳的周日动态

对两个海水养虾池溶解有机碳（ＤＯＣ）及颗粒有机碳（ＰＯＣ）的周日动态进行了研究,结果表明,ＤＯＣ的浓度,１４：００～１８：００下降,１８：００～２２：００升高,之后又下降,周日波动幅度为３．２２ｍｇ／Ｌ（１池）及１．２４ｍｇ／Ｌ（２池）ＰＯＣ浓度白天（６：００～１８：００）升高,夜间（１８：００～次日６：００）下降,周日波动幅度为１．２８ｍｇ／Ｌ（１池）及１．２６ｍｇ／Ｌ（２池）。ＰＯＣ浓度高的虾     

Filtration of Green Algae and Cyanobacteria by Freshwater Mussels in the Partitioned Aquaculture System

Abstract.— The freshwater mussel Elliptio complanata was provided water containing green algae and cyanobacteria delivered from the Partitioned Aquaculture System (PAS) at eight flow rates to determine algal filtration rates as mg of particulate organic carbon (POC)/kg wet tissue weight per h. The dominant taxon in cyanobacterial waters was Microcystis while the dominant taxa in green algal waters were Scenedesmus and Ankistrodesmus . The cell counts of Scenedesmus and Ankistrodesmus were the only algal taxa that were significantly different between the incoming water and water filtered by mussels. Filtration rates of POC obtained from green algal water were significantly greater than from cyanobacteria-dominated waters at all flow rates. A significant increase in mean filtration rate was observed as flow rates increased. The filtration rate of green algae increased as POC concentration increased, peaking at 28 mg C/L. A maximum filtration rate was not observed with cyanobacterial waters.     

Sedimentation and sediment characteristics in sea cucumber Apostichopus japonicus (Selenka) culture ponds

Annual sedimentation, re-suspension rates and contents of particulate organic carbon (POC), particulate organic nitrogen (PON) and total phosphorus (TP) in the sediment were investigated in two sea cucumber culture ponds at Rongcheng, Shandong Province, China. The results showed that the average flux of total particulate matter in the ponds was 22.1 g m² d⁻¹. The average re-suspension rate of the sediment in the ponds was 81.7%. The re-suspension rates in spring and autumn were higher than those in summer and winter. The mean contents of POC, PON and TP in the sediment of the ponds were 4.4, 0.5 and 0.6 (mg g⁻¹), respectively, and the mean contents of Chlorophyll a (Chl a) and pheophytin in the sediment were 8.1 and 12.1 μg g⁻¹ respectively. The POC, PON and TP contents in the sediment of the ponds increased during the period of sea cucumber aestivation (summer) and hibernation (winter), while they decreased during the feeding periods. The organic matter accumulation rate and the contents of POC, PON, TP, Chl a and pheophytin in the sediment were even lower than those in the pond without sea cucumber (P<0.05). The results demonstrated that sea cucumber culture can effectively stop nutrient accumulation at the bottom of the cucumber culture ponds.     

Trials on Pacific oyster (<Emphasis Type="Italic">Crassostrea gigas</Emphasis> Thunberg) rearing in the middle Adriatic Sea by means of different trays

The aim of this study was to compare the growth of juvenile Pacific oysters (mean weight 2.22 g; mean length 26.8 mm) reared with the suspended technique using three different types of trays fixed to long lines at a mussel farm located in the middle Adriatic Sea. Growth, mortality rate and quality traits of oysters cultured in a new type of tray (EXP) were compared to those of specimens reared in conventional trays (CON) and in “poches” (POC). Culture density was fixed at 0.03 oysters cm⁻² in all the tray types. After 11 months of growth, oysters reared in all the tray types reached marketable size, weighing between 94.08 and 110 g without significant differences. Length (98.8–103.3 mm), width (61.1–70.5 mm) and height (31.6–34.1 mm) did not show significant variations. The condition index showed differences among EXP (93.17%) compared to CON (81%) and POC oysters (72.87%), and significant differences were found between those reared at the surface and the bottom, regardless of tray type. Concerning mortality, the EXP group (7.5%) recorded significantly smaller losses than CON (18.4%) trays and POC (31.6%).     

Effect of temperature and phytoplankton concentration on Nile tilapia Oreochromis niloticus (L.) filtration rate

Nile tilapia Oreochromis niloticus (L.) held in timed‐pulse feeding chambers, were provided with algal‐rich water dominated by either green algae (Scenedesmus, Ankistrodesmus, Chlorella and Tetraedron) or cyanobacteria (Microcystis) to determine the effect of temperature and phytoplankton concentration on filtration rates. Green algae and cyanobacteria filtration rates were measured as suspended particulate organic carbon (POC) kg^?1 wet fish weight h^?1. Ivlev's filter‐feeding model described the relationships between filtration rates and suspended POC concentration of green algae and cyanobacteria. Filtration rates of both green algae and cyanobacteria increased linearly as water temperature increased from 17 °C to 32 °C and were significantly higher in the warm‐water regime (26–32 °C) than in the cool‐water regime (17–23 °C). Filtration rates at 95% saturation POC (FR₉₅) in green algal and cyanobacterial waters were 700 mg C kg^?1 h^?1 and 851 mg C kg^?1 h^?1 in the warm‐water regime and 369 mg C kg^?1 h^?1 and 439 mg C kg^?1 h^?1 in the cool‐water regime respectively. The FR₉₅ in warm water were achieved at lower POC concentrations than in cool water.     

Comparative Nile tilapia and silver carp filtration rates of Partitioned Aquaculture System phytoplankton

Nile tilapia (Oreochromis niloticus) and silver carp (Hypophthalmichthys molitrix) held in timed-pulse feeding chambers were provided water dominated either by green algae (Scenedesmus, Ankistrodesmus and Tetraedron) or by cyanobacteria (Microcystis) to compare filtration rates (FRs). FRs were expressed as suspended particulate organic carbon (POC)/kg wet fish weight/h and as phytoplankton units filtered based on counts. Nile tilapia and silver carp filtration significantly reduced phytoplankton number of both taxonomic groups with the larger phytoplankton being filtered proportionally more than the smaller phytoplankton. Nile tilapia FR of green algae was significantly higher than silver carp; however, silver carp FR of cyanobacteria was higher than Nile tilapia. Ivlev's 90% saturation FRs (FR₉₀) in green-algal and cyanobacterial water sources were 702 and 812 mgC/kg/h for Nile tilapia and 414 and 1028 mgC/kg/h for silver carp, respectively. Silver carp were observed to reach these FR₉₀ values at lower POC concentrations than Nile tilapia with both green algae and cyanobacteria.     

Microbial mineralization of organic matter in sinking particles,bottom sediments and seawater in a coastal fish culturing area

Microbial mineralization rates in sinking particles, bottom sediments and seawater were determined in a coastal fish (red sea bream Pagrus major) culturing area to clarify the mineralization process of organic matter (OM) in the entire water column. The mineralization rates of ¹⁴C‐labelled glutamate and glucose per unit volume were highest in the sinking particles and were 131–572 and 7–49 times higher than those of the seawater and bottom sediments respectively. The turnover time of glutamate tended to be shorter than that of glucose at all three sites of the water column. Bacteria appeared to prefer amino acids to monosaccharides because amino acids could be utilized as both energy and nitrogen sources. The sedimentation rate of particulate organic carbon (POC) derived from phytoplankton accounted for 9–61% of the total POC, and it was particularly high in early summer (61% and 50% at fish cage and non‐cage stations respectively). The present study clearly shows that sinking particles serve as an important site of microbial mineralization process of OM within the water column, and that phytoplankton production was another serious cause of organic pollution of the seafloor in addition to the organic wastes directly discharged from fish farms.     

Effect of Nile tilapia, Oreochromis niloticus (L.), size on phytoplankton filtration rate

Four different‐sized (390±3, 140±2, 40±2, 16±1 g) Nile tilapia, Oreochromis niloticus (L.), stocked at the same biomass in timed pulse feeding chambers were provided 27–29°C water dominated by Microcystis (82%) and Scenedesmus (18%) to determine the effect of fish size on filtration rates. The number of Microcystis and Scenedesmus units filtered from the water decreased significantly with increasing tilapia size. The shaping constants and maximum filtration rates for Ivlev's feeding model used to describe the relation between filtration rates and the suspended particulate organic carbon (POC) concentrations were significantly different among the four sizes. Filtration rates of 763, 671, 512 and 300 mg C kg^?1 h^?1, which correspond to 70%, 82%, 86% and 90% saturation levels, were achieved at POC levels of 30, 32, 32 and 33 mg C L^?1 for 16, 40, 140 and 390 g Nile tilapia respectively. Smaller tilapia achieved these rates at lower POC concentrations than larger tilapia.