渤海南部牙鲆的食性及摄食的季节性变化

1051尾渤海南部牙鲆的胃含物分析表明,渤海南部牙鲆为捕食性(游泳生物食性)鱼类,其食物成分有30余种,以底栖虾类中的口虾蛄、鲜明鼓虾、日本鼓虾、脊尾褐虾,软体动物的日本枪乌贼及鱼类中的斑(鱼祭)、鳀鱼、黄鲫、六丝矛尾虾虎鱼及焦氏舌鳎等动物为主要食物。牙鲆除冬季外,其余时间均强烈摄食,而且其摄食的季节性变化明显:春季以鱼类(重量占80.9％)及甲壳类(18.6％)为主要食物;夏季以鱼类(83.5％)及软体动物类(13.1％)为主要食物;秋季主要摄食鱼类(87.9％);冬季则主要摄食鱼类(73.2％)及甲壳类(19.7％)。     

长江口东滩湿地斑尾刺虾虎鱼的栖息亚生境选择和食性差异

2015年7月至2016年6月每月在长江口东滩湿地西南水域的光滩、盐沼(以海三棱藨草为主)和潮沟3种亚生境进行斑尾刺虾虎鱼的样本采集,分析斑尾刺虾虎鱼的丰度和食性差异.结果表明:6—11月均采集到斑尾刺虾虎鱼样本,以幼鱼为主,其他月份未采集到.其中,7月采集数量最多,为71尾,11月仅采集到3尾.潮沟中共采集到93尾,分别是光滩和盐沼的5.2和4.9倍.6—11月斑尾刺虾虎鱼的平均体长和体质量均呈逐渐增加趋势.斑尾刺虾虎鱼主要摄食虾类、蟹类、昆虫类和多毛类等10大类30小类饵料生物.其中,虾类是最重要的饵料类别,并以安氏白虾等白虾属为主;蟹类以相手蟹属为主;昆虫类以小划蝽等蝽科昆虫成虫为主;鱼类饵料的质量百分比相对较高,但数量比例很低.不同亚生境斑尾刺虾虎鱼的饵料组成差异较大.7—11月斑尾刺虾虎鱼的摄食等级随体长增大而明显增大,秋末(11月)平均摄食等级可达3.不同亚生境间的斑尾刺虾虎鱼丰度差异与其摄食饵料不同有关.     

长江口盐沼植被生境内斑尾刺虾虎鱼食性特征

根据2015年5月至2016年4月在长江口东滩盐沼湿地水域采集的斑尾刺虾虎鱼样本数据,分析了该生境斑尾刺虾虎鱼的生物学和食性特征。结果表明:共采集到斑尾刺虾虎鱼186尾,其中6—8月采集的数量较高,而其他月份较低。约96%个体为幼体(平均体长109 mm),平均摄食等级为1.5。斑尾刺虾虎鱼主要摄食虾类(IRI(%)=69.05)、鱼类(IRI(%)=17.31)、蟹类(IRI(%)=11.51)和双壳类(IRI(%)=0.95)等11大类41小类饵料生物;虾类作为最重要的饵料类别,其生物量、数量和出现频次百分比均排列第一,以安氏白虾(Exopalaemon annandalei)、日本沼虾Macrobrachium nipponense)、长额刺糠虾(Acanthomysis longirostris)等虾类为主要饵料。鱼类饵料中,以大鳍弹涂鱼(Periophthalmus magnuspinnatus)、大弹涂鱼(Boleophthalmus valenciennes)等虾虎鱼科鱼类为主要饵料。各月平均饱满指数P(%)波动较大,6—11月呈逐渐增加趋势。随着体长的增加,饵料组成中鱼类的比例呈逐渐增高趋势,成体个体的饵料中鱼类的生物量比例达65%以上,虾类的比例则下降明显。6—8月斑尾刺虾虎鱼白天样本中鱼类饵料的重量百分比显著高于夜晚(P0.01),约是夜晚的8倍;但虾类则是夜晚显著高于白天(P0.01),约是白天的2倍,而蟹类饵料的昼夜差异不显著。从等级聚类(即组平均法)的分类方法可知,斑尾刺虾虎鱼各体长组食物组成在10%相似性水平上可分为3类,即41—60、61—180 mm和181—200 mm。从营养生态位宽度来看,41—60 mm体长组生态位宽度值为0.86,而61—120 mm体长组随着体长的增大而增大,但121—160 mm体长组生态位有所降低。盐沼生境丰富的饵料环境为斑尾刺虾虎鱼提供了良好的摄食场所,同时盐沼植被茂密的植株也可为幼体提供躲避捕食者的最佳庇护所,初步证明盐沼对于斑尾刺虾虎鱼具有重要的生境价值。     

基于线性混合模型研究海州湾六丝钝尾虾虎鱼摄食生态

随着我国近海多种传统经济渔业资源的衰退,六丝钝尾虾虎鱼已成为海州湾等海域的优势鱼种之一,并在海洋食物网中发挥着重要作用。本研究根据2011年和2013—2016年春季和秋季在海州湾及其邻近海域进行的渔业资源底拖网调查,基于线性混合模型研究了海州湾六丝钝尾虾虎鱼的摄食习性以及影响其摄食的主要因素,并对其摄食策略进行分析。结果表明: 海州湾六丝钝尾虾虎鱼以虾类、双壳类、端足类等14个饵料生物类群为食,其中端足类、虾类、双壳类、蛇尾类是其主要的饵料类群。从饵料生物种类来看,六丝钝尾虾虎鱼摄食的饵料种类有37种,优势饵料生物有钩虾、细螯虾、独眼钩虾、彩虹明樱蛤和鲜明鼓虾等。线性混合模型分析表明,海州湾六丝钝尾虾虎鱼的摄食强度受体长、水深、季节、底层盐度的显著影响,其中,摄食强度与水深和底层盐度呈显著负相关关系,而与体长呈显著正相关关系,且春季的摄食强度显著高于秋季。聚类分析表明,以体长70 mm为界,可将六丝钝尾虾虎鱼划分为食性差异较大的两个体长组,其摄食随体长的变化主要与自身摄食能力与饵料生物丰度的变化有关。摄食策略分析表明,六丝钝尾虾虎鱼的营养生态位具有较高的表型间成分,对食物的种内竞争较低。本研究将有助于揭示六丝钝尾虾虎鱼的生活史特征,并为其资源的可持续利用和科学管理提供参考依据。     

食性对草鱼消化道发育及三种消化酶活性的影响

草鱼(Ctenopharyngodon idellus)是我国主要的淡水养殖经济鱼类之一,其食性随着生长发育而改变,能利用植物性和动物性两类饵料。草鱼幼鱼期食性分为三个阶段:浮游动物食性、食性转变阶段和草食性。草鱼食性在其早期发育中变化很大。动物性饵料,如浮游动物、底栖无脊椎动物是早期生长发育阶段重要的饵料成分;随着草鱼的生长,浮游甲壳动物和摇蚊幼虫则成为较重要     

莱州湾鱼类群落同功能种团的季节变化

利用2011年5月、8月、10月和12月底拖网调查数据,对莱州湾海域鱼类同功能种团特征及其季节变化进行了研究。全年调查共渔获鱼类49种,全部为硬骨鱼类。根据鱼类的摄食习性,调查海域鱼类可划分为浮游动物食性种团、浮游动物/底栖动物食性种团、底栖动物食性种团、底栖动物/游泳动物食性种团、游泳动物食性种团、杂食性种团和碎屑食性种团共7个同功能种团,其中底栖动物食性种团种类数最多(14种),底栖动物/游泳动物食性种团次之(12种)。碎屑食性种团生物量在全年处于第一优势地位,占32.8%;其次为浮游动物食性种团,占31.6%;再次为底栖动物/游泳动物食性种团,占25.0%。同功能种团多样性(HFD)和种类多样性(Hs)季节变化趋势相同,均在夏季达到最高值,冬季达到最低值;两者关系使用指数方程拟合效果最佳。浮游动物食性种团平均营养级为3.71、浮游动物/底栖动物食性种团为3.83、底栖动物食性种团为3.43、底栖动物/游泳动物食性种团为3.75、游泳动物食性种团为3.86、杂食性种团为3.73、碎屑食性种团为3.34。与20世纪80年代、90年代调查结果相比,目前莱州湾碎屑食性种团比例明显上升,游泳动物食性种团比例大幅下;底栖动物食性种团和游泳动物食性种团的平均营养级明显下降,碎屑食性种团平均营养级有所上升。     

胶州湾六丝钝尾虾虎鱼的摄食生态特征

根据2011年2-11月在胶州湾海域进行的4个季节的底拖网调查,共收集624尾六丝钝尾虾虎鱼样品进行胃含物分析,对其摄食生态进行了初步研究.结果表明:六丝钝尾虾虎鱼摄食的饵料种类有40余种,其中优势饵料生物有日本鼓虾、经氏壳蛞蝓和细螯虾等.其食物组成存在明显的季节变化,除在4个季节均大量摄食虾类外,春季主要摄食腹足类,夏季主要以鱼类为食,秋季主要摄食虾类,冬季摄食桡足类和端足类等小型甲壳生物的比例较高,这主要与胶州湾饵料生物种类和数量的季节性变化有关.随着体长的增长,六丝钝尾虾虎鱼摄食的饵料生物由小型的桡足类逐渐转变为个体较大的经氏壳蛞蝓、绒毛细足蟹和日本鼓虾等,食物组成呈现出明显的体长变化.典范对应分析(CCA)表明,水温和盐度是影响六丝钝尾虾虎鱼摄食的主要因素,其次是体长和pH.     

浙江七星列岛海洋特别保护区主要鱼类功能群划分及生态位分析

为揭示七星列岛省级海洋特别保护区鱼类群落现状, 于2014年秋季(11月)和2015年春季(5月)进行底拖网调查。利用生态位测度、非度量多维标度排序和等级聚类等方法对该海域鱼类功能群组成及生态位特征进行了研究。结果表明, 该区鱼类可划分为浮游生物食性、底栖动物食性、游泳动物食性、浮游生物/底栖动物食性、底栖动物/游泳动物食性和杂食性6个功能群。浮游生物食性、底栖动物食性和底栖动物/游泳动物食性功能群是秋季优势功能群, 浮游生物食性、游泳动物食性和杂食性是春季优势功能群。秋季, 主要鱼类生态位宽度值变化范围为0.28-3.84, 其中龙头鱼(Harpodon nehereus)、六指马鲅(Polydactylus sexfilis)、赤鼻棱鳀(Thrissa kammalensis)、红狼牙鰕虎鱼(Odontamblyopus rubicundus)、海鳗(Muraenesox cinereus)、尖头黄鳍牙鱼或(Chrysochir aureus)和叫姑鱼(Johnius belengerii)的生态位宽度值较高; 春季生态位宽度值变化范围为0.36-3.16, 其中带鱼(Trichiurus lepturus)、日本鳀(Engraulis japonicus)、蓝圆鲹(Decapterus maruadsi)、刺鲳(Psenopsis anomala)、龙头鱼和镰鲳(Pampus echinogaster)的生态位宽度值较高。秋季, 主要鱼类生态位重叠值在0-0.94之间波动; 春季, 主要鱼类生态位重叠值在0-0.92之间波动。以丰度数据平方根为基础, 利用非度量多维标度排序和等级聚类分析, 主要鱼类秋季可以分为4组, 而春季可以分为3组。上述结果表明, 保护区鱼类群落的营养结构和空间结构较好。     

长江口及邻近海域高营养层次生物群落功能群及其变化

通过对2006年6、8和10月在长江口及邻近海域3次调查采集样品的分析,对该水域的高营养层次生物群落的功能群组成及其变化进行了研究.结果表明：长江口及邻近海域高营养层次生物群落包括鱼食性、蟹食性、虾食性、底栖动物食性、浮游生物食性和广食性6个功能群.由于受海洋环境变化以及鱼类洄游活动的影响,各月份长江口及邻近海域高营养层次生物群落的组成及营养级都有较大的变化.6月高营养层次以鱼类、毛虾类和蟹类为主,以浮游生物食性功能群为主要功能群,营养级最低,为3.06;8月高营养层次以鱼类为主,虾食性功能群为主要功能群,营养级达到最高,为3.78;10月高营养层次虽仍以鱼类为主,虾蟹类比例增大,功能群以浮游动物食性和底栖动物食性功能群为主,营养级为3.58.     

基于碳、氮稳定同位素研究胶州湾普氏栉虾虎鱼的摄食习性

普氏栉虾虎鱼属于小型暖温性底层鱼类,是胶州湾鱼类群落中的优势种之一,在胶州湾食物网和生态系统中发挥着重要作用.本文应用碳、氮稳定同位素技术,基于胶州湾渔业资源底拖网调查采集的样品,对普氏栉虾虎鱼的摄食习性进行了研究.结果表明: 胶州湾普氏栉虾虎鱼的δ¹⁵N值范围为11.24‰～13.99‰,平均值为(12.70±0.70)‰,δ¹³C值范围为-20.67‰～-18.46‰,平均值为(-19.08±0.36)‰;各体长组的营养级范围为3.49～3.76,平均营养级为(3.62±0.21),其δ¹⁵N值和营养级与体长呈显著负相关,δ¹³C值与体长无显著相关性.普氏栉虾虎鱼摄食的主要饵料生物类群为多毛类、虾类和软体动物,浮游动物和颗粒有机物(POM)的饵料贡献率较小.聚类分析结果表明,普氏栉虾虎鱼各体长组食物组成的相似性均在92%以上,相似性较高,说明其摄食习性随体长变化无明显差异.普氏栉虾虎鱼在胶州湾生态系统中属于中级消费者,其摄食各饵料生物类群比例的变化可能是其营养级与体长呈负相关关系的主要原因.     

Dietary habits of the fanray Platyrhina tangi (Batoidea: Platyrhinidae) in Ariake Bay, Japan

The dietary habits of the fanray Platyrhina tangi were investigated by analyzing the stomach contents of specimens collected in Ariake Bay, Japan. Of 334 stomach specimens, 324 contained food and 10 (3.0%) were empty. The mean percentage weight of stomach contents per unit of body weight was 0.59%. Thirty-seven taxonomic levels of prey were identified. The most common prey was shrimp, followed by fish and mysids. There were no differences in the composition of the diet between sexes, but an ontogenetic dietary shift was observed. Shrimps were the most common prey in all size classes. In addition, smaller individuals frequently ate mysids, and larger individuals often consumed fish. Dietary breadth values increased with size. Trophic level analysis revealed that trophic level increased with size; however, this species is consistently a secondary consumer. Dental sexual dimorphism was also observed. Specifically, mature males had much longer and sharper cusps than females and immature males. Since males and females had similar diets, dental sexual dimorphism may be related to their reproductive behaviour.     

Feeding habits of horse mackerel, Trachurus trachurus (Linneaus, 1758), from the central Adriatic Sea

The feeding habits of the horse mackerel, Trachurus trachurus, from the central Adriatic Sea were investigated with respect to fish size and season. Stomach contents of 1200 specimens 12.9–37.6 cm total length (TL) taken at monthly intervals (January–December 1995) were analyzed. Of the total number of stomachs examined, 597 were empty (49.7%). This percentage varied significantly with season; the maximum number of empty stomachs was observed during January (80%) and February (82%) and a minimum number observed during July (15%) and August (19%). A total of 30 different prey species belonging to five major groups: Crustacea (Euphausiacea, Mysidacea, Decapoda), Cephalopoda, and Teleostei was identified in the stomach contents. Euphausiids were the most important ingested prey in all seasons as well as in small‐ and medium‐size classes (<28 cm TL). Two species of euphausiids, Nyctiphanes couchii (%IRI = 36.0) and Euphausia krohni (%IRI = 12.9), were the most frequent prey. The proportion of teleosts in stomach contents increased with the increasing size class of horse mackerel and was 15.5% IRI in >30 cm TL individuals. The mean weight of stomach contents increased significantly for fish larger than 24.1 cm TL, while the mean number of prey items significantly declined in the large‐size classes.     

Feeding ecology of Mediterranean razorfish Xyrichthys novacula in the Tyrrhenian Sea (Central Mediterranean Sea)

The stomach contents of 196 razorfish ( Xyrichthys novacula ), collected in the Tyrrhenian Sea (Ponza Island, Italy) between July and December 1994, were examined in order to assess the diet and to analyse size-related dietary variation of the species. The diet of X. novacula showed a strict relationship with well-sorted fine sand (SFBC) benthic species, mostly Mollusca and Echinodermata, as pointed out by the analysis at the specific level of the stomach contents. Mollusca Pelecipoda, essentially Acanthocardium tuberculatum and Echinodermata, with Echinocardium cordatum , made up 90% of the volume of prey of X. novacula. Mysidacea and Gastropoda were frequent but volumetrically less important. The study showed that male and female X. novacula were not effectively segregated by trophic dimension in the study area. The niche overlap between males and females in prey composition was pronounced, as evidenced by the significantly high values of Schoener's index with larger males that showed a greater tendency towards predation of large prey. The increment in length (L.I.) in males, despite a decrease in the percentage body weight increment (B.W.I.), could represent the result of a male reproductive feature: the lack of sperm competition allows the males much more energy to devote to growth than do that of the females of this species.     

Feeding habits of the fishes Lutjanus peru and Lutjanus guttatus (Pisces: Lutjanidae) of Guerrero, México

Diet composition of the Pacific snapper (Lutjanus peru) 130-684 mm fork length (FL) and the spotted snapper (Lugjanus guttatus) 120-550 mm FL, was analyzed. Monthly samples were obtained from commercial landings in three regions off the coast of Guerrero, Mexico. Percentage by number (%N), percentage by weight (%W), and percentage of occurrence (%O) were calculated for each prey and summarized as the index of relative importance. Both species are polyphagous predators feeding on a variety of prey: Sixty-eight prey items, mainly fish (%W = 50.9), crustaceans (%W = 35.6), and mollusks (%W = 7.2), were found in the stomach contents of L. peru, while 88 components were identified in the diet of L. guttatus, the most important prey being fish (%W = 50.8) and crustaceans (%W = 43.4). Diet overlap between species is not significant (p<0.05), indicating that competition for food is unlikely. Based on published values of the relative importance index, the diets of these Lutjanidae were analyzed considering different regions of the Pacific coast of Mexico and Costa Rica, and similarities among sites and species were discussed. The cluster analysis showed that similarities among species inhabiting in the same area are more important than within organisms of the same species living in different zones. Results suggest that prey availability rather than food selectivity, conditions the feeding behavior of these fish species.     

A DNA-based method for identification of krill species and its application to analysing the diet of marine vertebrate predators

Accurate identification of species that are consumed by vertebrate predators is necessary for understanding marine food webs. Morphological methods for identifying prey components after consumption often fail to make accurate identifications of invertebrates because prey morphology becomes damaged during capture, ingestion and digestion. Another disadvantage of morphological methods for prey identification is that they often involve sampling procedures that are disruptive for the predator, such as stomach flushing or lethal collection. We have developed a DNA-based method for identifying species of krill (Crustacea: Malacostraca), an enormously abundant group of invertebrates that are directly consumed by many groups of marine vertebrates. The DNA-based approach allows identification of krill species present in samples of vertebrate stomach contents, vomit, and, more importantly, faeces. Utilizing samples of faeces from vertebrate predators minimizes the impact of dietary studies on the subject animals. We demonstrate our method first on samples of Adelie penguin (Pygoscelis adeliae) stomach contents, where DNA-based species identification can be confirmed by prey morphology. We then apply the method to faeces of Adelie penguins and to faeces of the endangered pygmy blue whale (Balaenoptera musculus brevicauda). In each of these cases, krill species consumed by the predators could be identified from their DNA present in faeces or stomach contents.     

Interannual study of Chinstrap penguin’s diet and reproductive success at Laurie Island, South Orkney Islands, Antarctica

Inter-annual variability in the diet of Chinstrap penguins (Pygoscelis antarctica) at Laurie Island, South Orkney Islands was examined based on stomach contents of adults coming ashore during the 1997/1998–2001/2002 breeding seasons. Krill (Euphausia superba) dominated the diet either as frequency of occurrence (in 100% of samples), number (>99%), and percentage contribution in weight (>99.5%). Other prey items were minor but did vary between years. The contribution in weight of fish, amphipods and cephalopods ranged between 0.01–0.5, <0.01–0.14 and 0–0.03, respectively. Although minor components varied slightly along the years, the weight of stomach contents was significantly different. It was found that for a given weight the maximum observed percentage of undigested krill resulted negatively correlated with the stomach contents total weight. The proportion of whole krill observed in individual penguins, expressed as a fraction of the maximum corresponding to its weight was used to characterize the prevailing conditions in each season.     

Gelatinous zooplankton (ctenophores,salps and medusae): an important food resource of fishes in the temperate SW Atlantic Ocean

This study quantifies the occurrence of gelatinous zooplankton in the stomach contents of fishes from the southwest Atlantic Ocean (33°–55°S). More than 69,000 fish stomachs belonging to 107 species were examined. A total of 39 fishes were documented as consumers of gelatinous zooplankton, 23 of which were newly discovered. Three gelatinous organism consumption categories are recognized: (1) very frequent consumers (10 species, six of which were exclusive); frequent consumers (five species); and occasional consumers (26 species). Three types of gelatinous prey (ctenophores, salps and medusae) were found in the stomach contents of fishes. Ctenophores were consumed at high levels across almost the entire continental shelves of Argentina and Uruguay. Salps were frequent prey on the slope and southern shelf. In contrast, medusae were consumed in coastal areas, slopes and the southern shelf. Classification methods (group average sorting of the Bray–Curtis similarity measures based on log (X?+?1)-transformed percentage data) determined six areas where fishes predated on gelatinous organisms. SIMPER (similarity percentages) analysis determined which fishes contributed more to the consumption of gelatinous organisms. Results revealed that two fish species (Stromateus brasiliensis and Squalus acanthias) had high gelatinous zooplankton predation rates throughout the entire study area, while another six species (Patagonotothen ramsayi, Helicolenus dactylopterus lahillei, Macrourus holotrachys, Merluccius hubbsi, Schroederichthys bivius, and Macruronus magellanicus), while widely distributed, seemed to have specific areas where consumption occurred. This study not only provides new knowledge about the importance of gelatinous zooplankton in the diet of numerous fishes, but might also be valuable for planning and managing local fisheries.     

Stomach evacuation rate in the planktivorous Antarctic fish Pagothenia borchgrevinki

Summary Specimens of the Antarctic fish Pagothenia borchgrevinki were collected from just below the sea-ice in McMurdo Sound over the period 5–16 November 1987. The stomach contents of 54 freshly captured fish were analysed and showed very strong similarities with an earlier, more extensive, dietary analysis conducted at the same location (Foster et al. 1987). There was as much variation in stomach contents from fish within a school, as there was between schools, contrary to the expectation that fish within a school would have shared a more common feeding history. Fish were maintained in holding tanks for up to 48 h after capture; groups were sacrificed at 6 h intervals and the stomach contents analysed to determine evacuation rates. Evacuation rates of total stomach contents and individual prey species were fitted with an exponential model of decay. The exponential time constant for decay of stomach contents was 32 h (Table 2), while time constants for individual prey species ranged from 12 h for small prey species to 49 h for the larger crustacea. The feeding rate of P. borchgrevinki on important prey species was calculated from the above data (Table 2). Low feeding rates, and the low numbers of P. borchgrevinki argue against removal by predation as being the explanation for the observed reduction in plankton numbers seen in shallow waters (Foster 1989).     

Application of DNA metabarcoding on faeces to identify European catfish Silurus glanis diet

In this study, the results of conventional stomach‐content analysis are compared with the recent DNA metabarcoding approach on faeces to identify fish species consumed by non‐native European catfish Silurus glanis in the Garonne River (south‐western France), with a special emphasis on anadromous prey. Fourteen prey species were identified in the stomach contents or faeces, including four anadromous fish species. Despite higher intestine than stomach emptiness, more species were identified through faecal analysis (11 of 14) than through stomach‐content analysis (five of 14) suggesting that DNA metabarcoding on faeces is an efficient, non‐intrusive technique to study the diet of predatory fishes.