砂粒粒径与砂层厚度对单体筐养养殖系统中三疣梭子蟹(Portunus trituberculatus)幼蟹摄食行为与生长特性的影响研究

在三疣梭子蟹(Portunus trituberculatus)的单体筐养养殖系统中, 试验了生态掩体(砂盒)中不同的砂粒粒径大小以及砂层厚度对梭子蟹幼蟹摄食行为与生长特性的影响。砂粒粒径设三个水平,分别为: >2mm、<0.2mm 以及混合砂; 砂层厚度有0cm、2cm、5cm、8cm 四个水平。试验共进行6天, 结果表明: 砂粒粒径及砂层厚度对梭子蟹幼蟹的摄食与生长都有明显的影响。从砂粒粒径看, 幼蟹在细砂(SPS)中挖洞休息, 蟹体与砂面呈30—45°角, 仅露眼睛及触角在外。一天内有3—6 次进食,总进食时间为(142.7±22.52)min, 在摄食次数、总进食时间、平均摄食量[(0.2427±0.0137) g/gBW]、以及蜕皮及成活率都远高于其它粒径组, 该组中幼蟹的体重增长最快, 增加了(0.814±0.113)g, 增长率为91.5%±3.43%; 而该组的饵料系数(FCR)最低为1.17±0.11。因此, 筐养养殖系统砂掩体的砂粒粒径最好为0.2 mm 以下。砂层厚度也有类似结果, 5 cm 以上厚度养殖效果最佳。平均摄食量为(0.2087±0.0046) g/gBW, 该厚度下, 幼蟹无死亡、100%蜕皮, 体重也增加最快, 增加了(0.791±0.121)g, 增长率为88.9%±3.74%, 饵料系数(FCR)达到1.37±0.23, 表明筐养系统掩体中砂层厚度要在5 cm 以上。三种保护性酶类(SOD, POD, CAT)活性随着砂粒粒径变小和砂层厚度增加而降低, 而消化酶类(淀粉酶、蛋白酶、脂酶)活性则表现与保护性酶类相反特性。从两类酶的活性变化也能证实, 在优选条件下(细砂、厚度>5 cm), 幼蟹所受的胁迫在降低。     

Population succession and feeding of scyphomedusae, Aurelia aurita, in a eutrophic tropical lagoon in Taiwan

Seasonal dynamics and feeding of scyphomedusae, Aurelia aurita, were investigated monthly from 1999 to 2002 in relation to environmental conditions in Tapong Bay, a eutrophic tropical lagoon in southwestern Taiwan. Medusae appeared throughout the year but exhibited seasonal dynamics that were correlated with hydrographic features in the bay. Most ephyrae of A. aurita occurred mainly in the lower flushed and eutrophic inner bay, and during the cold, dry season between November and February. They grew to young medusae with a maximum abundance in spring (March–May), but their numbers abruptly decreased during the warm and rainy summer season in June–September. The remaining medusae then grew rapidly to a maximal size of 29 cm. Mature females spawned in the following autumn when precipitation decreased but zooplankton food was still abundant. These mature individuals decreased in size after spawning and in winter. Gut content analysis revealed that A. aurita fed mainly on copepods and copepod nauplii and less on bivalve larvae and fish eggs. Prey selectivity indices indicated that larger medusae selected positively for copepods while small size medusae preferred copepod nauplii. The overall feeding effect of A. aurita on the standing stock of zooplankton was significant (27%) in the bay. Our results suggest that tidal flow and dense oyster culture pens were the two most important factors influencing the spatial distribution pattern of A. aurita in the bay, while precipitation affected the population abundance seasonally; decreasing water temperature coincided with the mass release of ephyra in late autumn and winter.     

Trophic interactions in the coastal ecosystem of Sri Lanka: An ECOPATH preliminary approach

This study attempts to assemble and summarize existing information in order to build a general representation of the trophic interactions within the shallow coastal ecosystem of Sri Lanka. A multispecific ecosystem-based approach on trophic relationships and their possible variations was performed using ECOPATH. Thirty-nine functional groups were considered representing all trophic levels in the food web.     

Dietary shift and feeding intensity of <Emphasis Type="Italic">Stenobrachius leucopsarus</Emphasis> in the Bering Sea

The food habits of the dominant myctophid Stenobrachius leucopsarus were examined in the central basin of the Bering Sea in relation to oceanographic conditions, in summer 2002 and 2003 and spring 2006. S. leucopsarus exhibited an ontogenetic and seasonal dietary shift. In spring, small fish (≤40 mm) preyed mainly on Neocalanus flemingeri/plumchrus whereas large fish fed mainly on Neocalanus cristatus. In summer, small fish preyed mainly on Metridia pacifica whereas large fish fed mainly on euphausiids (Thysanoessa spp.). In the summer of 2003, when water temperature in the epipelagic layer (≤100 m) was warmer, reflecting the prevalence of the Alaskan Stream, small-sized S. leucopsarus showed a higher stomach content index, perhaps reflecting the greater abundance of M. pacifica. Thus, the present study shows that the physical variability in the epipelagic layer affects not only diets but also feeding performance of micronekton.     

Preliminary studies on the role of protozoa in the food web of Donghu Lake

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双棘黄姑鱼早期发育阶段的摄食习性与生长特性

2002年5~6月,在集美大学水产学院水产试验场,采用生态学方法对人工培育的双棘黄姑鱼(Nibeadiacanthus(Lacpde))仔、稚、幼鱼的摄食习性与生长特性进行分析。结果表明,在人工培育条件下,双刺黄姑鱼仔、稚、幼鱼的摄食率达93.1%,摄食量占体质量的4.09%~21.07%,日摄食量占体质量的23.67%~57.24%;摄食具明显的昼夜节律,黄昏为摄食高峰。摄食量与体质量的关系式为y=0.1267x0.7878,全长与日龄的关系式为L=1.8603e0.0723D,体质量与日龄的回归方程为M=0.0203e0.2484D。全长与体质量的回归方程为M=0.0024L3.4633。     

文蛤稚贝的摄食、呼吸和排泄研究

利用实验生态学的方法研究了在25℃下文蛤稚贝对4种单细胞藻类的摄食率和不同温度对文蛤稚贝呼吸、排泄的影响。研究结果表明,单位质量的文蛤稚贝在单位时间内滤食4种藻类的质量和个数差异极为显著;温度对文蛤稚贝的耗氧率、排氨率也有显著影响,在12~32℃范围内,耗氧率、排氨率随着温度的升高而增大,O∶N值也随之而升高;在3组试验温度下呼吸Q10的平均值为6.06,排泄Q10的平均值为2.59。     

饥饿对日本囊对虾幼体发育、摄食及存活的影响

本实验研究了饥饿对日本囊对虾蚤状幼体Ⅰ期发育、摄食及存活的影响。结果表明．饥饿对对虾幼体的变态存活有显著影响，饥饿时间与变态率及变态时间呈线性关系．饥饿对日本囊对虾幼体首次摄食影响显著。本实验中，日本囊对虾的蚤Ⅰ幼体的PNR100应为40h。     

台湾海峡及邻近海域主要无脊椎动物食性特征及其食物关系研究

对台湾海峡及邻近海域14种主要经济无脊椎动物的胃含物进行了鉴定分析。结果表明：这些无脊椎动物对饵料生物无明显的选择性，均为混合食性。其食性类型可分为：游泳生物食性类型、游泳动物和底栖动物混合食性类型、底栖生物和浮游动物食性类型、底栖生物食性类型、浮游动物和游泳动物食性类型。10种甲壳动物和4种头足类的营养级范围分别为1．64～2．60级和2．04～2．88级。除周氏新对虾(Metapenaeus joyneri)、角突仿对虾(Parapenaeopsis cornuta)和鹰爪虾(Trachypenaeus curdrostris)属第二营养层次的杂食性动物外，其它的均属第三营养层次的肉食性动物。拥剑梭子蟹(Portunus haanii)、秀斑好(Caarybdis feriatus )、哈氏仿对虾(Parapenaeopsis harduickii)和杜氏枪乌贼(Loligo duvaucelii)的食物生境宽度较大，它们对各种饵料生物的利用更趋均衡。4种头足类之间、3种蟹类之间食物重叠显著。长尾类、短尾类、鱼类和腹足类是台湾海峡主要无脊椎动物营养层次能量传递中的关键功能类群。