倒刺鲃属三个种之间种间杂交的初步研究

采用人工催产和干法授精技术,进行了以中华倒刺鲃、倒刺鲃为母本与其父本及黑脊倒刺鲃雄鱼的种间杂交实验,获得4个杂交组合和2个自交组合,在(27±0.5)℃温度条件下,对其F₁卵膜径、受精率、孵化率、孵化时间、畸形率、子代早期形态特征与成活率进行了比较,同时,观察了胚胎发育及其异常现象,结果表明:以中华倒刺鲃为母本的F₁卵膜径差异不显著;以倒刺鲃为母本的F₁卵膜径,在多细胞期时差异不显著,在耳石期时,倒刺鲃♀×中华倒刺鲃♂F₁卵膜径显著大于母本(P<0.05)。杂种F₁的受精率、孵化时间与母本差异不显著,畸形率显著高于母本(P<0.05)。中华倒刺鲃杂种F₁的孵化率较高,与母本差异不显著(P<0.05)。倒刺鲃♀×中华倒刺鲃♂F₁的孵化率与母本之间差异不显著,倒刺鲃♀×黑脊倒刺鲃♂F₁的孵化率显著低于母本(P<0.05)。中华倒刺鲃杂种F₁仔鱼早期发育阶段存在死亡高峰期,成活率显著低于母本(P<0.05)。中华倒刺鲃种间杂交和倒刺鲃♀×黑脊倒刺鲃♂杂种F₁既具有父本特征,同时又具有母本特征,初步证明倒刺鲃属种间杂交是可行的。     

黑脊倒刺鲃的人工繁育技术

<正>倒刺鲃属鱼类属于鲤科鲃亚科,属内有5种,分别为黑脊倒刺鲃、中华倒刺鲃、倒刺鲃、云南倒刺鲃、多鳞倒刺鲃,其中黑脊倒刺鲃也叫光倒刺鲃,在福建俗称光鱼、粗鳞。此属鱼类易给人的错觉:被认为是草鱼。目前,有关倒刺鲃属鱼类的研究报道主要是前3种(黑脊倒刺鲃、中华倒刺鲃、倒刺鲃),分布于我国南方乃至西南地区诸水系。3个种各有特点:中华倒刺鲃生长速度中等,绝对怀卵量大,雌鱼性成熟年龄4龄~5龄;倒刺     

鄱阳湖通江水道越冬时期鱼类群落的栖息地适宜性分析

鄱阳湖通江水道是多种洄游性鱼类完成生活史过程的重要通道, 具有重要的生态功能, 对于长江中下游鱼类资源的养护及其多样性维持至关重要。为了解越冬时期鄱阳湖通江水道中不同体长鱼类资源的空间分布规律及栖息生境状况, 本研究将鱼类声学探测、生境遥感定量制图分析和三维水动力模拟相结合, 分别绘制出 3 种不同体长鱼类群落的水深(SI_D)、流速(SI_V)、坡度(SI_S)等单因子生境适宜度指数曲线, 并利用乘积法建立栖息地适宜性指数(habitat suitability index, HSI)模型, 对通江水道中不同水域的鱼类生境适宜度进行对比和评估。结果表明, 鄱阳湖通江水道越冬时期鱼类平均全长为(10.1±5.73) cm, 主要分布在屏峰山以北的湖口县、鞋山和屏峰附近 3 个水域; 小体长鱼类群组(1~20 cm)水深的生境适宜度曲线为双峰型, 最适宜水深包括 3.06~4.59 m 和 9.18~12.24 m 两个区间, 流速为 0.05~0.13 m/s, 坡度为 0~2.23°; 中等体长组(20~40 cm)及大体长组(＞40 cm)鱼类适宜的水深、流速和坡度的生境适宜度曲线均为单峰型, 其中中等体长组最适宜栖息的生境因子范围为水深 9.18~13.77 m、流速 0.05~0.13 m/s 和坡度 0~2.23°, 大体长组为 13.77~15.3 m、0.10~0.13 m/s 和 0~2.23°。     

不同光强和温度对长石莼（缘管浒苔）光合作用和叶绿素荧光参数的影响

利用脉冲振幅调制叶绿素荧光仪对不同光照和温度条件下长石莼（缘管浒苔）光合作用和培养条件进行了优化。结果表明，长石莼（缘管浒苔）在25 ℃和72 μmol/(m2·s)条件下，其F_v/F_m、F_m、F_v和α值最高，分别高达0.74、4 567、3 406和0.305，低于该点为光不饱和，高于该点为光抑制，偏离越大，下降越显著（P<0.01），其中在5 ℃和35 ℃时最小，分别是25 ℃最高值的32.24%~64.88%和22.99%~53.44%；光强为18 μmol/(m²·s)和216 μmol/(m²·s)时最小，其F_v/F_m、F_m、F_v和α值分别是25 ℃和72 μmol/(m²·s)条件下最高值的44.94%~82.62%和51.82%~76.72%。F₀变化不太明显，5~30 ℃为先上升后下降或再上升变化趋势，35 ℃为先下降后上升变化趋势。拟合参数α显示，长石莼（缘管浒苔）在达到光饱和点前通过增加光能吸收来增强光合作用，在光抑制后则迅速减少。rETR_maxDuncan检验表明，高温/低温和高光强对长石莼（缘管浒苔）光合作用影响显著（P<0.01）。总体上看，长石莼（缘管浒苔）光合作用和生长适宜条件为15~25 ℃和54~72 μmol/(m²·s)，过高或过低均不适宜。且温度排序为25>20>15>30>10>5>35 ℃，光照强度排序为72>54/108>36/162>18/216 μmol/(m²·s)。     

光强对多肋藻小孢子体生长及抗氧化生理的影响

在实验室条件下, 研究了多肋藻(Costaria costata)孢子体在不同光强下的生长、光合作用、营养成分以及抗氧化能力, 以期揭示多肋藻小孢子体对光强的适应性, 为多肋藻海区栽培提供参考。结果发现, 藻体在光照强度 30~120 μmol/(m² ·s)均具有较快的生长速率, 其中 60 μmol/(m² ·s)下相对生长速率(RGR)和藻体 PSII 最大光化学量子产量(F_v/F_m)均最高。总光合速率(P_t)和最大表观光合速率(P_nmax)在培养前期(5 d)随光强增加而上升, 随着培养时间的延长(10 d)在 60 μmol/(m² ·s)下最高; 在 60 μmol/(m² ·s)下, 藻体呼吸速率(R_d)较低。叶绿素 a (Chl a)、岩藻黄素 (Fucox)和类胡萝卜素(Car)的含量为低光组稍高于高光组(P＞0.05)。粗蛋白、脂肪和粗纤维的含量与光强具有一定的正相关性, 而碳水化合物含量则与光强呈负相关。结果表明, 60 μmol/(m² ·s)适宜多肋藻小孢子体的生长。在较低或较高光强下, 藻体呼吸作用均显著增强; 此外, 高光下, 可溶性蛋白含量显著上升, 低光下, 抗超氧阴离子自由基(ASAFR)、超氧化物歧化酶 SOD)、抗坏血酸过氧化物酶(APX)比活力较高, 过氧化氢酶(CAT)比活力则在低光和高光下均下降, 这些生理响应对多肋藻小孢子体适应不同光强具有重要的调节作用。     

辐射沙洲海域浮游动物特征和吕泗渔场的成因分析

为探讨辐射沙洲海域浮游动物饵料变化规律和吕泗渔场的形成机制,于2012年5月(春季)和2012年9月(秋季)采集了苏北浅滩辐射沙洲核心海域浮游动物样品,通过聚集强度、方差贡献、优势度及逐步回归等指标和方法,分析了苏北浅滩浮游动物时空分布与辐射沙洲地形等环境因子的关系。结果显示:春、秋两季,浮游动物的生物量和丰度分布均表现出沙脊水域高于潮沟水域,且存在明显的季节差异。春季不同水域平均生物量分别为沙脊水域606.63 mg/m³、沟底水域428 mg/m³、沟口水域为178.55 mg/m³,秋季为沙脊水域208.01 mg/m³、沟底水域181.30 mg/m³、沟口水域60.47 mg/m³;春季不同水域平均丰度分别为沙脊水域560.76个/m³、沟底水域389.39个/m³、沟口水域161.28个/m³,秋季为沙脊水域184.15个/m³、沟底水域56.42个/m³、沟口水域112.14个/m³。春、秋季桡足类均占绝对优势。研究表明:研究水域浮游动物分布特征与地形和潮波系统有关,沙脊水域的浮游动物数量高于潮沟水域,其原因一方面是潮沟地形造成沙脊上流速较小,潮沟中流速较大,另一方面东海前进潮波与南黄海旋转潮在沙脊线附近汇合,导致处于交汇处的沙脊水域水动力较弱,因此浮游动物容易在沙脊水域集聚和摄食。苏北浅滩潮沟系统海域的饵料水平远高于其他水域,其优势种群主体为桡足类,是经济鱼类主要的饵料组分,这是吕泗渔场成为我国著名渔场的重要环境因素。     

单环刺螠生物扰动对沉积物-水界面氮磷扩散通量的影响

为了解单环刺螠生物扰动作用对沉积物-水界面氮磷扩散通量的影响及其持续性,于2020年11—12月,采用室内实验生态学的方法,设置低密度 (LD,500 尾/m²)、中密度 (MD,2 500 尾/m²)、高密度 (HD,8 300 尾/m²)处理组和1个对照组 (CO,0 尾/m²),进行了2 d为一个实验时段,为期20 d的模拟实验。结果显示,处理组溶解无机氮(DIN)扩散通量变化范围为10.6~765.3 μmol/(m²·d),与对照组相比,低、中、高处理组的DIN通量分别提高了57%、76%、88%。NH₄⁺是DIN的主要贡献者,对DIN的贡献在低、中、高处理组中分别占55%、65%和80%。与对照组相比,低、中、高密度组的平均NH₄⁺通量分别提高了39%、111%和257%,与低、中密度处理组平均NH₄⁺通量相比,高密度处理组分别提高了43.7%和23.6%。在第2~10天,NH₄⁺通量处于持续增加的趋势。处理组PO₄³⁻通量变化范围为−7.85~6.42 μmol/(m²·d),第2~6天,处理组PO₄³⁻通量持续增加。研究表明,单环刺螠的生物扰动能够持续地促进DIN由沉积物向水体中扩散,且存在明显的密度效应。研究结果将为深入认识单环刺螠在水层-底栖系统耦合过程中的生态作用提供基础数据。     

鲤科鱼类的流速选择及其与食性的关系

为考察食性对鲤科鱼类流速选择行为的影响,本研究选择滤食性的鲢摘要可以不放拉丁学名,请补充在正文出现第一个的位置和鳙、草食性的草鱼和中华倒刺鲃、以及杂食性的鲫和锦鲫作为实验对象;在(25 ± 1) ℃条件下将单尾实验鱼置于梯度流速选择仪（流速范围为11.86-65 .45 cm/s,等距离划分为5个流速区域）中拍摄1 h,采用Ethovision XT19软件分析视频资料并计算六种实验鱼在不同流速区域平均停留时间（Pt,%）、平均进入频次（F,次 / h）和单次进入停留时间（T,s）等流速选择行为指标。结果显示：（1）六种实验鱼的流速选择行为均呈现出两种流速偏好趋势,一类表现为偏好缓流（或静水）（最低流速区域的Pt >50%）,被定义为Ⅰ型;另一类个体Pt随水流速度的变化出现不同程度的波动,最大Pt通常出现在某一中等流速区,则定义为Ⅱ型;（2）食性对鱼类流速偏好行为有显著影响,Ⅰ型个体中滤食性鱼类对静水或缓流偏好显著大于其他两种食性的鱼类,其中鳙和鲢的Ⅰ型个体在最低端流速区域Pt大于92%;滤食性鲢和鳙的Ⅱ型个体偏好流速高于杂食性的鲫和锦鲫。草食性的草鱼和中华倒刺鲃Ⅱ型流速偏好均不明显,但其在中间速流速区域F值最大。研究表明：六种鲤科鱼类的流速偏好行为存在Ⅰ型和Ⅱ型的表型分化并且差异明显,实验鱼的流速偏好行为与食性有关。     

2020年湘江长沙段仔稚鱼资源现状及其对水文环境的响应

为了解湘江下游长沙段仔稚鱼资源现状,2020年5-6月,在湘江下游长沙香炉洲江段(28°20′17″N ,112°53′5″E)进行为期57天的仔稚鱼资源调查。结果显示：(1)采集点共出现鱼苗汛7次,第一次为5月22日,最后一次为6月29日,7次鱼汛平均水温为26.5±0.57 ℃,网口平均流速为0.237±0.095m/s;(2)共采集仔稚鱼54.8万尾,分别隶属5目、8科、41种,其中,鲤科鱼类30种、占比73.2%,分析鱼卵类型和生态习性发现,主要以产沉性卵鱼类(23种)和广适性鱼类(24种)为主,分别占56.1%、58.5%,分析相对重要性指数发现,优势种为9种：子陵吻鰕鯱(Rhinogobius giurinus,2416.9)、飘(Pseudolaubuca sinensis,1507.0)、大鳍鱊(Acheilognathus macropterus,451.5)、银鲴(Xenocypris argentea,321.9)、鲤(Cyprinus carpio,314.6)、?(Hemiculter leucisculus,219.1)、黄尾密鲴(Xenocypris davidi,206.2)、鲫(Carassius auratus,179.9)和麦穗(Pseudorabora parva,158.7);(3)白天时段鱼苗总密度(0.093 ind/m_³)远低于夜间,约为夜间(0.567 ind/m_³)1/6,鲴类的昼夜差异更加明显,夜晚占比为白天的25倍,经Spearman检验,优势种及家鱼种类中,大鳍鱊、子陵吻鰕鯱、银鲴及草鱼(Ctenopharyngodon diellus)昼夜分布存在显著差异(P＜0.05);(4)分析发现,表层鱼苗密度(0.548 ind/m_³)为中下层(1.048 ind/m_³)的1/2,且子陵吻鰕鯱、银鲴、鲤鱼(Cyprinus carpio)及草鱼垂直分布存在显著差异(P＜0.05);(5)冗余分析(RDA)发现,流速对方差的贡献率为90.8%,与鱼苗总密度变化呈显著性相关(P=0.042),但与优势种及家鱼种类未表现出显著关系性,水温为9.2%,未表现出显著相关性。综上,湘江长沙段仔稚鱼资源丰富,且存在一定的昼夜垂直分布规律,应进一步完善湘江长沙段仔稚鱼资源的时空分布规律及其对水文环境的响应的调查研究,为长江十年禁渔效果评估提供理论依据和数据参考。     

安徽省无为县水产养殖场中华倒刺鲃引进养殖试验

<正>中华倒刺鲃(Spinibarbus denticulatus Oshima)隶属鲤形目,鲤科,倒刺鲃属,主要分布于我国长江上游及其支流,为嘉陵江重要的名贵经济鱼类之一,有个体大,生长快,食性杂,抗病能力强的特点,是我国名贵经济鱼类。中华倒刺鲃肉质细嫩、肥美多脂,富含各种氨基酸,深受消费者喜爱。近年来,由于江河生态环境破坏、过度捕捞、水质污染等原因,野生资源日趋枯竭,货源紧俏。我国长江上游省份,如四川、贵州、湖北等地已     

Habitat selection by rainbow trout Oncorhynchus mykiss in a California stream: implications for the Instream Flow Incremental Methodology

We quantified microhabitat selection of rainbow trout (Oncorhynchus mykiss) at 2 flows (low= 1.13 m³. s^?1 and high =4.95 m³. s^?1) in the Pit River, California. Flows were controlled by an upstream dam and habitat availability was similar during 4 sampling periods at low flow and 2 periods at high flow. A principal components analysis reduced 6 microhabitat variables to 3 new variables that explained 80% of the observed variance. The 3 components loaded heavily on velocity variables, depth variables and substrate. Microhabitat selection generally differed among macrohabitats (i. e., pools, runs, and riffles). Rainbow trout selected different microhabitats at high flow relative to low flow in response to the availability of deeper, faster water. At low flow, depth and velocity selection were positively correlated with seasonal temperature change for adults but not juveniles. Rainbow trout apparently sought shelter in interstitial spaces in the substrate of runs and riffles during the day in early winter. Generally, large rainbow trout were observed in pools, intermediate-sized fish in runs, and small trout in riffles. The largest fish occurred in slow, deep areas of pools, where they moved slowly without orientation to flow and were not observed feeding, whereas small fish generally faced upstream and fed in all habitat types. Foraging forays were directed up in the water column at velocities similar to the mean water column velocities at holding positions. Rainbow trout were the most abundant species in 76% of the population survey stations. Other species that might have influenced microhabitat selection by rainbow trout were uncommon.     

The effect of flow on the competition between the alien racer goby and native European bullhead

The racer goby is an invasive Ponto‐Caspian fish spreading throughout Europe. They threaten a native species of similar biology, the European bullhead, by displacing them from shelters. These shelters are necessary for reproduction as well as for protection against predators and hydrodynamic forces. However, abiotic conditions may strongly modify the outcome of an interspecific competition in the wild. Nevertheless, little is known of the effect of flow velocity on the competition between these rheophilic species, although this factor is crucial for their distribution in the field. We video‐recorded fish behaviour for 2 h in single‐species and mixed‐species pairs in the presence of single shelters at three flow velocities: 0, 10 (a velocity preferred by the racer goby) and 30 cm·s^?1 (a velocity greater than preferred by the racer goby) to determine whether the invader can deprive the native species of its shelter. At the flow of 0 and 10 cm·s^?1, the racer goby exhibited aggressive behaviour towards bullhead, and this restricted the time spent by the bullhead in the shelter. Moreover, although the flow of 30 cm·s^?1 inhibited racer goby aggression, the time spent by the bullhead in the shelter in interspecific competition was still reduced when compared to intraspecific controls. Our results suggest that under natural conditions, the racer goby displace bullheads from their shelters even at flow velocities greater than optimal for the racer goby.     

Development of Nursery Systems for Black Sea Bass Centropristis striata

Black sea bass (Centropristis striata) are territorial fish and cannibalism is a concern when rearing juveniles in intensive systems. Three studies were conducted to provide information for development of suitable tank nursery systems for juvenile black sea bass (3.6–4.5 cm; 0.8–1.7 g). Studies were performed at the Marine Resources Research Institute, Charleston, SC, using 1.5‐m diameter × 0.8 m deep tanks connected to recirculating seawater systems. The studies examined growth and survival at different stocking densities, selection and utilization of habitats, and, effects of water velocity on positioning and movement of fish. In study 1, fish were stocked at biomass densities of 126.7, 253.3, and 506.7 Wm³ and reared for 56 days with no habitats. No difference in growth was detected although fish reared at the lower densities had significantly lower mortality (mean 7.9%) as compared to those at the highest density (28.0%). At the highest density, cannibalism appeared to be a substantial cause of mortality. In study 2, three habitat types were used, (1) two‐tier structure constructed from plastic grating with 15 mm square openings (volume = 0.015 m³); (2) PVC pipe bundle (volume = 0.004 m³); (3) rock aggregate (volume = 0.008 m³). Of the habitats, the most utilized habitat (62.9%) was the two‐tier layered structure that allowed movement in all directions. The next utilized type was the pipe bundle (25.6%) with the openings inhabited by the largest juveniles in each tank. Overall, a mean of 18.2% of the fish were observed using habitats. Study 3 examined water velocities ranging from 0.01 to 0.12 m/sec. Most fish became concentrated in the tank bottom area having a water velocity in the range of 0.040.09 m/sec. At these velocities there were few aggressive interactions. Smaller fish inhabited the areas outside this velocity range. At the higher velocities, the small fish swam vigorously to maintain their position in the water column. At the low velocities, sporadic incursions of larger fish occurred presumably to attempt to cannibalize or to defend territory. Results from these studies help to define characteristics of nursery systems for rearing juvenile black sea bass.     

Assessing near‐bed velocity in a recruiting population of the endangered freshwater pearl mussel (Margaritifera margaritifera) in Ireland

相似文献   

草鱼洄游适宜流速条件与适应阈值

洄游通道的连通性及其水文条件,是制约鱼类正常洄游和产卵繁殖的关键因素,现有的生态流量相关研究更多侧重于产卵场栖息地模拟,忽略了鱼类洄游水流条件的重要性。为了探究流速条件对鱼类洄游上溯的影响,选取体长(55±5)cm的草鱼(Ctenopharyngodon idellus)为实验对象,通过搭建鱼类洄游仿真河道,营造不同的流速工况,观察不同情景方案下实验鱼群上溯洄游情况,并利用模糊逻辑法对鱼类上溯洄游率、平均上溯时间及上溯持续性等实验参数进行综合分析,探索草鱼洄游的适宜流速条件与适应阈值。结果显示,在流速0.20m/s以下时,草鱼基本无上溯行为;流速0.25～0.80m/s,70%样本在15min内完成上溯,但0.25～0.30m/s时,鱼群上溯缺乏明显的持续性;0.90～1.00m/s时,80%以上样本在5min快速完成上溯;流速超过1.1m/s时,上溯成功率明显降低。研究表明,实验草鱼洄游的适宜流速范围是0.40～1.00m/s,而刺激草鱼洄游的最小流速阈值是0.20m/s。相关结果可为河流生态水力学模拟和河流生态修复以及水利工程生态调度提供技术支撑。     

A simple method for assessing minimum flows in regulated rivers: the case of sea lamprey reproduction

• 1. The sea lamprey (Petromyzon marinus) is an anadromous species that occurs in some large Iberian rivers, such as the Tagus, and their tributaries. The sea lamprey populations of the River Tagus are threatened by habitat loss and overexploitation, which means that conservation measures, including maintenance of the spawning grounds, are urgent. Habitat loss is mainly due to hydroelectric and flood‐control dams that have affected the migration and spawning habitats of anadromous species. The main objective of this study was to use a simple, cost‐effective method to assess a minimum instream flow for the regulated River Tagus. The method used was based on the wetted perimeter–discharge relationship, but accounted for the habitat requirements of spawning sea lampreys.
• 2. In 1998, a habitat survey was conducted along a 30 km segment of the River Tagus downstream from Belver Dam (the first impassable obstacle for fish movements), a stretch that includes potential habitats for spawning sea lampreys. Four spawning areas were identified, and in each one a representative reach was selected along which to collect elevation and geo‐positional data. For a range of flows from 0 to 50 m³ s^?1, hydraulic modelling and studies of spawning habitat availability were conducted, both for each reach and for the total wetted area of the four reaches.
• 3. The availability of spawning habitat was limited by flow. Results showed that the present minimum flow downstream from Belver Dam (8 m³ s^?1) is insufficient to ensure suitable habitat conditions in a significant part of the segment studied; gains in wetted usable area were more substantial with discharges of up to 20 m³ s^?1, and thus a minimum flow of 10–20 m³ s^?1 was recommended. Potential spawning habitat could be improved by increasing instream flow to at least 50 m³ s^?1. The impacts of the Belver release regime on anadromous species are discussed and a more ‘ecologically oriented’ form of water management is suggested

. Copyright © 2004 John Wiley & Sons, Ltd.     

松花江梧桐河生态修复工程鱼类栖息地模拟及调查

通过对松花江一级支流梧桐河中下游河道栖息地模型模拟和实地鱼类调查,分析了修复工程丁坝的水动力变化对鱼类栖息地的改善作用。基于流量内增加法(IFIM),应用水生生物栖息地模型(River 2D),考虑鱼类栖息地的流速、水深、遮蔽回水面积比3项指标,定义栖息地为差、中、良3个等级,模拟从小到大4个不同流量条件下顺直河道和丁坝河道鱼类栖息地等级的分布及变化,并通过实地鱼类调查数据验证修复工程丁坝对鱼类栖息地质量的改善情况。结果表明,在不同流量条件下,顺直河道和丁坝河道鱼中等级栖息地占84%以上;从生态流量到多年平均流量的过程中,顺直河道和丁坝河道不同综合适宜性指数(Combined Suitable Indexes,CSI)等级的栖息地面积变化较大,其中两者CSI差等级的栖息地面积占比分别减少4.9%和4.8%,顺直河道CSI中等级的栖息地面积占比升高4.9%,丁坝河道CSI中等级的栖息地面积占比下降6.0%,丁坝河道CSI良等级的栖息地面积占比从0%升高到10.8%;当流量大于多年平均流量26.42 m~3/s时,各种等级的栖息地比例变化不大,多年平均流量对鱼类生长而言是最佳下限流量。从2016年和2017年9月两河段的鱼类调查情况来看,丁坝河段鲫(Carassius auratus)和蛇鮈(Saurogobio dabryi)的平均体重和平均体长更大,模拟和实测数据一致,说明丁坝在一定程度上改善了鱼类栖息地的质量。     

金沙江乌东德水电站生态调度目标鱼类筛选研究

生态调度是缓解水电工程对鱼类不利影响的有效措施之一,确定生态调度目标鱼类是制定生态调度方案的基础和前提。在野外调查和查阅相关文献资料的基础上,运用物种濒危系数、遗传价值系数和物种价值系数对金沙江乌东德坝址至白鹤滩坝址之间分布的53种土著鱼类进行生态调度需求次序的定量研究,结果表明,处于生态调度需求1级的鱼类有4种,为圆口铜鱼、长鳍吻鮈、中华金沙鳅和齐口裂腹鱼,这些鱼类均属长江上游特有鱼类,也是受水电开发影响较为显著的种类;处于生态调度需求2级的鱼类有14种,包括长江上游特有鱼类11种,这些鱼类产卵繁殖对流水生境均有一定需求;处于生态调度需求3级的鱼类有28种,这些鱼类以广适型种类为主,对水流条件的要求不高;处于生态调度需求4级的鱼类有7种,多为常见的小型鱼类,其产卵繁殖对生境要求不高。评价结果基本反映了乌东德坝下江段鱼类对生态调度的实际需求,考虑到产漂流性卵鱼类和产粘沉性卵鱼类繁殖需求的差异,综合确定圆口铜鱼和齐口裂腹鱼为乌东德水电站生态调度的主要目标鱼类,长鳍吻鮈、中华金沙鳅等作为兼顾目标鱼类。     

Water velocity in commercial RAS culture tanks for Atlantic salmon smolt production

An optimal flow domain in culture tanks is vital for fish growth and welfare. This paper presents empirical data on rotational velocity and water quality in circular and octagonal tanks at two large commercial smolt production sites, with an approximate production rate of 1000 and 1300 ton smolt/yr, respectively. When fish were present, fish density in the two circular tanks under study at Site 1 were 35 and 48 kg/m³, and that in four octagonal tanks at Site 2 were 54, 74, 58 and 64 kg/m³, respectively. The objective of the study was twofold. First, the effect of biomass on the velocity distribution was examined, which was accomplished by repeating the measurements in empty tanks under same flow conditions. Second, the effect of operating conditions on the water quality was studied by collecting and analysing the water samples at the tank’s inlet and outlet. All tanks exhibited a relatively uniform water velocity field in the vertical water column at each radial location sampled. When fish were present, maximum (40 cm/s) and minimum (25–26 cm/s) water rotational velocities were quite similar in all tanks sampled, and close to optimum swimming speeds, recommended for Atlantic salmon-smolt, i.e., 1–1.5 body lengths per second. The fish were found to decrease water velocity by 25% compared to the tank operated without fish. Flow pattern was largely affected by the presence of fish, compared to the empty tanks. Inference reveals that the fish swimming in the tanks is a major source of turbulence, and nonlinearity. Facility operators and culture tank designers were able to optimize flow inlet conditions to achieve appropriate tank rotational velocities despite a wide range of culture tank sizes, HRT’s, and outlet structure locations. In addition, the dissolved oxygen profile was also collected along the diametrical plane through the octagonal tank’s centre, which exhibits a close correlation between the velocity and oxygen measurements. All tanks were operated under rather intensive conditions with an oxygen demand across the tank (inlet minus outlet) of 7.4–10.4 mg/L. Estimates of the oxygen respiration rate in the tank appears to double as the TSS concentration measured in the tank increases from 3.0 mg/L (0.3 kg O₂/kg feed) up to 10–12 mg/L (0.7 kg O₂/kg feed). Improving suspended solids control in such systems may thus dramatically reduce the oxygen consumption and CO₂ production.