Food habits of fishes in the mangrove estuary of Urauchi River,Iriomote Island,southern Japan

The food habits of 67 fish species collected from the mangrove estuary of the Urauchi River, Iriomote Island, southern Japan were investigated using gut content analysis. Ontogenetic changes in food preference were recognized in nine species, including mugilids, gerreids, mullids, gobiids and tetraodontids. In most cases, juveniles of these species fed mostly on small crustaceans (e.g. calanoid and cyclopoid copepods and gammaridean amphipods) or detritus. With their subsequent growth, larger prey items (e.g. crabs and polychaetes) became dominant. A cluster analysis based on dietary overlaps showed that the mangrove fish assemblage comprised eight trophic groups (zooplankton, small benthic crustacean, large benthic crustacean, polychaete, fish, detritus, plant and insect feeders). Of these, large and small benthic crustacean feeders, which consumed mainly crabs and gammaridean amphipods, respectively, were the most abundantly represented in terms of species, whereas polychaete and insect feeders were each represented by only two species.     

Food habits of small fishes in seagrass habitats in Trang,southern Thailand

To clarify the feeding habits of seagrass fishes, we examined the gut contents from 42 fish species collected in seagrass habitats in Trang. Thirteen species showed ontogenetic and/or seasonal changes in food-use patterns. Smaller individuals generally preyed on small planktonic items (e.g., copepod larvae) or small benthic/epiphytic crustaceans (e.g., harpacticoid copepods), with subsequent changes to other prey items (e.g., shrimps, crabs, detritus and filamentous algae) with growth. The most important dietary items for the seagrass fish assemblages comprised benthic/epiphytic crustaceans, detritus, and planktonic copepods. Cluster analysis based on dietary overlaps showed that the seagrass fishes comprised eight feeding guilds (large benthic/epiphytic crustacean, detritus, planktonic animal, small benthic/epiphytic crustacean, mollusc, invertebrate egg, polychaete, and fish feeders). Of these, the first three guilds were the most abundantly represented, whereas the last three were each represented by only a single species.     

Microhabitat differences in crab assemblage structures in a subtropical mangrove estuary on Iriomote Island,southern Japan

Crab assemblage structures in sandy flat, muddy flat and mangrove forest microhabitats in a mangrove estuary of the Urauchi River, Iriomote Island, southern Japan, differed clearly among the three microhabitats, species and individual numbers being greater inside the mangrove forest than on the flats. A similarity index showed distinct differences in species composition among the microhabitat assemblages, primarily due to the differential distributions of dominant species, such as the soldier crab Mictyris guinotae, sentinel crab Macrophthalmus convexus and sesarmid crab Perisesarma bidens. A canonical correspondence analysis indicated that the differences likely arose from among-microhabitat differences in the physical environment, the mangrove forest being characterized mainly by structurally complex mangrove roots, lower soil porewater temperatures and higher relative substrate elevation, the sandy flat by lower organic content of the sediment and higher porewater oxygen amount, and the muddy flat by higher levels of sediment water and organic material. The findings suggested that microhabitat-related physical differences are important factors determining crab distribution patterns in mangrove estuaries.     

Effects of mangrove deforestation on fish assemblage at Pak Phanang Bay,southern Thailand

Daytime sampling using a seine net was conducted at Pak Phanang Bay (Nakhon Si Thammarat Province, Thailand) in February and July 2006, to determine differences in fish assemblage structures between a mangrove site and an adjacent site completely cleared of mangroves. The overall numbers of fish species and individuals were significantly higher at the mangrove site than the cleared site in both months. Although benthic crustacean feeders showed more species and individual numbers at the mangrove site in both months, the opposite was found for zooplankton feeders. A cluster analysis, based on the abundance of each species, demonstrated that the fish assemblage structures were distinctly different between the two sites. In addition, significant differences in length frequency distributions for each of the four most abundant species were found between the sites in February and/or July. Small individuals of Scatophagus argus, Ambassis nalua, and Tetraodon nigroviridis were more common at the mangrove site, and of Chelon subviridis at the cleared site. These results suggest that mangrove deforestation exerts marked effects on fish assemblages.     

Comparison of microbial community structures in intensive and extensive shrimp culture ponds and a mangrove area in Thailand

ABSTRACT:   A pelagic bacterial community structure was examined in experimental intensive shrimp culture ponds that have a shrimp–mangrove complex aquaculture system, an extensive shrimp culture pond and a mangrove area in Thailand by denaturant gradient gel electrophoresis analysis of polymerase chain reaction amplified partial 16S rRNA genes. Bacterial community structure in the intensive shrimp culture ponds was distinguishable from that of the mangrove area. In the extensive shrimp culture pond, the bacterial community structure resembled that in the mangrove area, but bacterial abundance was as great as that in the intensive shrimp culture ponds. Among the intensive shrimp culture ponds, the bacterial community structure was different between a closed culture system and a shrimp–mangrove complex culture system. Moreover, the bacterial community structure in mangrove planted ponds was close to those in the intensive shrimp culture ponds when shrimp culture was conducted, but it was close to those in the mangrove areas without shrimp culture. These results suggest that intensive shrimp culture with shrimp feed input affects the bacterial community structures in pond water.     

Differences in fish assemblage structures between fragmented and continuous seagrass beds in Trang,southern Thailand

Fish assemblage structures in fragmented and continuous seagrass habitats in Trang Province, Thailand, were examined in detail to elucidate the effects of habitat fragmentation. The assemblage structures clearly differed: fish species diversity was apparently higher in the fragmented seagrass beds, although total fish numbers did not differ between them. A total of 37 fish species were collected, including 24 and 34 species from the continuous and fragmented beds, respectively. Thirteen species were restricted to the fragmented beds, compared with three restricted to the continuous beds. In addition, eight species were more abundant in the fragmented beds and only two in the continuous beds. Such differences may have arisen, at least in part, from differences in microhabitat diversity and the relative amounts of microhabitats between the two habitat types, as well as specific microhabitat preferences of the resident fishes. Although fragmented beds supported greater fish species diversity at the present study sites, it is axiomatic that habitat fragmentation caused by anthropogenic disturbance is unacceptable, with seagrass-habitat conservation being essential for both the preservation of high overall biodiversity and the successful management of local fisheries.     

Selection of spawning habitat by several gobiid fishes in the subtidal zone of a small temperate estuary

We examined the spawning sites of several gobiid fishes in the subtidal zone of a small temperate estuary and determined the relationship of the nest abundance of each species with several environmental conditions, including water temperature, salinity, median particle size, proportion of silt and clay, current width, maximum water depth, distance from each site to the river mouth, and density of objects (boulders, cobbles, empty oyster shells, and empty clam shells) in the water. During this study, we found 115 nests belonging to the following six species: Favonigobius gymnauchen, Tridentiger obscurus, Leucopsarion petersii, Acanthogobius lactipes, Rhinogobius giurinus, and Tridentiger trigonocephalus. Stepwise multiple regression analysis, which was used to determine the best model for the nest abundance of all species, revealed that the nest abundance of each species clearly increased with an increase in the density of spawning substrates, such as cobbles and bivalve shells. These results show that the density of spawning substrates is a crucial factor affecting the selection of spawning habitats by each species.     

Assemblage structure and habitat use of fishes in a Central European submontane stream: a patch-based approach

Abstract –  We examined macrohabitat patch level assemblage composition and habitat use patterns of fishes over four seasons in a second-order submontane stream (Danube drainage, Hungary). Rainfall data indicated that our study included both high- and low-water periods, and hence our results may be applicable to broader time scales. Principal component analysis of physical habitat data from 13 macrohabitat patches indicated that these patches represented a riffle-pool continuum. Correspondence analysis of fish assemblage structure data from these patches identified a continuum in assemblage composition that was positively correlated with the habitat continuum. The riffle fauna was dominated by stone loach ( Barbatula barbatula ), whereas chub ( Leuciscus cephalus ) were most abundant in pool patches. We detected little evidence of seasonality in either fish assemblage structure or habitat use. Fish density did not differ significantly among macrohabitat patches in two (summer and autumn 1999) of three seasonal samples, although riffle patches displayed significantly higher fish abundance in late spring 2000. This difference primarily was due to higher abundance of juvenile stone loach in riffles. Two species, stone loach and minnow ( Phoxinus phoxinus ), displayed generalized habitat use patterns, whereas chub and rare species (i.e., gudgeon, Gobio gobio ; dace, Leuciscus leuciscus ; Barbus petenyi ; and burbot, Lota lota ) were significantly over-represented in pool habitats. We hypothesized that pool specialists (i.e., chub and rare species) were responding primarily to the increased depth of these habitats. Nevertheless, our data did not demonstrate the presence of separate pool and riffle habitat guilds. In conclusion, we believe that our understanding of stream fish ecology will be greatly facilitated by use of a 'patch-based approach'.     

The conservation implications of spatial and temporal variability in the diurnal use of Bahamian tidal mangrove creeks by transient predatory fishes

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Demography of southern Australian bottlenose dolphins living in a protected inverse estuary

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台州南部近岸海域春秋季主要鱼类生态位及其种间联结性

根据2016年秋季(10月)和2017年春季(4月)台州南部近岸海域的渔业资源调查资料,将2次调查中分别出现的优势种及重要种定义为主要鱼类,并采用相对重要性指数、生态位测定、方差比率、卡方检验、Pearson相关检验和Spearman秩相关检验等方法分析主要鱼类间的生态位和种间关系。结果显示,秋季主要鱼类8种,春季11种,2季共有主要鱼类5种。秋季主要鱼类的生态位宽度值与生态位重叠值总体上略高于春季,秋季广生态位种(Bi≥2.40)、中生态位种(1.60≤Bi<2.40)和窄生态位种(Bi<1.60)依次有4种、3种和1种,春季则依次有4种、5种和2种;秋季生态位重叠显著(Oik≥0.6)的种对数占总种对数的32.14%,春季则仅占12.73%。秋季,总体联结性分析结果显示主要鱼类间总体上呈显著负关联,卡方检验、Pearson相关检验和Spearman秩相关检验显示群落中正负关联比依次为1.50、1.33和2.11,其检验显著率依次约为0%、17.86%和10.71%。春季,总体联结性分析结果结果显示主要鱼类间总体上呈不显著负关联,卡方检验、Pearson相关检验和Spea...     

长江口渔场鱼类组成和多样性

利用2000年在长江口渔场4个季节的调查资料,对该渔场的鱼类组成和多样性进行了研究。结果表明:共捕获鱼类73种,隶属于11目,40科,62属。季度出现频数F=1~4的鱼类种数分别为38、9、12、14种。所有出现种类的适温性以暖温性和暖水性基本相当,在所出现的海洋性种类、河口性(低盐性)种类、河海洄游性种类三种生态类型中,以海洋性种类占绝对优势,河海洄游性种类相对较少。根据优势度曲线可以看出夏季优势种最突出,秋季优势种最不明显。通过相似性指数的分析表明,季节间的相似性以春季和冬季较为相似,夏季和秋季差异较大。各个季节的多样性指数D、H'、J以春季和冬季较接近,夏季和秋季相差较大,并且四个季节中以秋季较高。在4个季节的调查中,各站鱼类多样性指数相差较大,可能是因为出现频率小且数量少的偶见种相对较多     

Phenology and spatial and temporal distribution of larval fishes in a partially channelized warmwater stream

We studied the phenology and spatial and temporal dynamics of larval fish abundance with light traps from 5 locations along the length of Luxapalilia Creek, a partially channelized warmwater stream in northeastern Mississippi over 2 spawning seasops (March through August 1992 and 1993). The dominant, early spring spawners were catostomids (early-April to late-May) and darters (mid-March to early-June) whereas summer spawners were mainly cyprinids (mid-May to August) and centrarchids (late-May to August). The relative abundance of larvae collections differed based on: 1) site, 2) location, 3) date, 4) year, and 5) in larval stage. Total numbers of larvae and CPUE were high in mid- to late summer in downstream locations in both years when: 1) temperatures were high, 2) water velocities were low, and 3) depths were shallow compared to upstream locations. More mature larvae (meso- and metalarvae) were more common in the downstream locations whereas less mature larvae (yolk-sac and protolarvae) were more abundant at the upstream locations. The downstream channelized portion of Luxapalila Creek resembled a lentic habitat with littoral zones characterized by slow water velocities, shallow depths, fine sediments, and vegetation. Larvae of darters (Etheostorna and Pcrcina), which require gravel bars and swift currents, were not collected in great numbers downstream, although members of the Ictiobinae (Carpoides and Ictiobus), cyprinidae and centrarchidae (Lepomis spp., Pomoxis spp. and Micropterus spp.) were more abundant downstream than upstream. This suggests that the natural, upstream locations acted as sources of larvae for the channelized downstream location.     

The culture of the southern bay scallop in Tampa Bay, an urban Florida estuary

Bay scallop, Argopecten irradians concentricus (Say), stocks were collected from a Homosassa (Florida) population in 1991 and were kept in seawater from Bayboro Harbor on Tampa Bay, an urban Florida estuary. They were fed with Isochrysis galbana and Tetraselmis sp. Spawning was allowed to occur after the scallops became ripe. The hatching rate of the F1 eggs to D-shaped larvae was 72%. Settlement and metamorphosis began 11 days after fertilization. When spat reached a shell height of 0.8 mm in the laboratory, they were placed with substrates into 300 and 800 m mesh bags, and later in lantern nets, suspended from a dock in Bayboro Harbor. The F1 scallops successfully survived to gonad maturity in the fall of 1992, with mean (sd) shell height of 49.8 (4.0) mm on 6 September 1992. The scallops experienced heavy mortality during the summer, partially as a result of heavy fouling. From early August to October of 1992, F1 scallops grown in Bayboro Harbor were successfully spawned in the laboratory. Growth and survival of the F2 scallops were comparable to those of the F1 scallops. Results have shown that bay scallops can complete an entire life cycle in an urban estuary such as Tampa Bay, and a hatchery for bay scallops on the estuary can assist in the restoration of the population. Fouling represents a possible severe limitation and alternatives to caging for grow-out should be considered.     

胶州湾5种虾虎鱼类的营养和空间生态位

应用Shannon-Wiener指数和Pianka重叠指数分析了胶州湾5种虾虎鱼类的食物组成、营养生态位宽度、空间生态位宽度及其重叠,通过计算营养空间二维生态位重叠指数探讨了5种虾虎鱼类种间食物竞争与空间分布的关系。结果表明,胶州湾的5种虾虎鱼均属底栖动物食性,其中斑尾刺虾虎鱼(Synechogobius ommaturus)主要以虾类、多毛类和鱼类为食,而六丝钝尾虾虎鱼(Amblychaeturichthys hexanema)、红狼牙虾虎鱼(Odontamblyopus lace-pedii)、纹缟虾虎鱼(Tridentiger trigonocephalus)和钟馗虾虎鱼(Tridentiger barbatus)则主要摄食桡足类、钩虾、涟虫等小型底栖甲壳动物。在5种虾虎鱼中,六丝钝尾虾虎鱼的营养生态位宽度最高(2.65),纹缟虾虎鱼的空间生态位宽度最高(2.01),而红狼牙虾虎鱼的营养生态位宽度和空间生态位宽度均最低(分别为1.26和0.97)。5种虾虎鱼之间的营养生态位重叠指数在0.03~0.64之间,其中六丝钝尾虾虎鱼与钟馗虾虎鱼的营养生态位重叠指数最高(0.64);空间生态位重叠指数在0.08~0.91之间,最高值出现在红狼牙虾虎鱼与钟馗虾虎鱼之间(0.91);营养空间二维生态位重叠指数在0.0032~0.3648之间,其中钟馗虾虎鱼与六丝钝尾虾虎鱼的营养空间二维生态位重叠指数最高(0.3648),因此最有可能出现激烈的食物竞争,其他鱼种之间则通过营养或空间生态位的分化而降低了种间竞争的程度。     

Vertical distributions of two herbivorous cichlid fishes of the genus Tropheus in Lake Tanganyika, Africa

The vertical distributions of two herbivorous cichlid fishes, Tropheus moorii and Tropheus duboisi, were studied on the rocky slope at Luhanga and Bemba, 12 km apart, in Lake Tanganyika, Zaire, Africa. At Luhanga, where T duboisi were not present, T. moorii ranged from the shoreline to a site 30 m deep. At Bemba, T moorii occupied areas less than 18 m and T duboisi areas between 5 and 30 m. In the overlapping zone, 5–18 m depth, each fish held an intra- and interspecific feeding territory, involving size-dependent dominance relationship between neighbors irrespective of species. We indicate that the vertical distributions of these species are restricted by competitive interactions.     

Effect of shrimp farming organic waste on food availability for deposit feeder crabs in a mangrove estuary, based on stable isotope analysis

We have investigated the impact of shrimp farming waste on benthic invertebrates in a mangrove estuary in southern Thailand. Stable carbon and nitrogen isotope analyses were used to assess the contribution of aquaculture feed as a nutrient source for benthic invertebrates (fiddler crabs Uca annulipes, U. bengali, and U. forcipata) and to compare the organic origin of sediments in tributaries with and without a shrimp farm. The isotopic contributions of shrimp feed to crabs varied between the tributaries: in the tributary with the farm, the crabs had higher contributions from shrimp feed, whereas there was only a small contribution from aquaculture feed in crabs from the reference tributary. In contrast, the contribution of shrimp feed to the sediment did not differ between the tributaries, the contributions to sediments from aquaculture feed were, in general, quite low. Based on these results, we suggest that, in mangrove estuaries, changes in the food sources of several surface feeder invertebrates would be an effective indicator of the possibility that aquaculture waste was affecting the benthic ecosystem.     

南黄海三种石首鱼类的食性

根据2000—2002年秋季和冬季在南黄海进行的定点底拖网调查,利用多元统计分析方法,研究了黑鳃梅童(Collichthys niveatus)、皮氏叫姑鱼(Jobnius belengerii)和小黄鱼(Pseudosciaena polyactis)的食物组成及其差异,摄食随海区、季节和体长的变化,以及3种石首鱼类摄食器官的形态差异对摄食的影响。结果表明：(1)3种鱼的优势饵料生物各不相同,食物组成存在显著差异;(2)3种鱼的食物组成均随海区和季节的不同而有显著的差异;(3)3种鱼的食物组成和饵料多样性都有明显体长变化,黑鳃梅童和皮氏叫姑鱼的饵料多样性随体长的增大而升高,小黄鱼则相反;(4)黑鳃梅童和小黄鱼种内不同体长问的食物重叠指数较高,而皮氏叫姑鱼则较低,3种鱼的种问食物重叠指数位于0．50～0．56;(5)主成分分析(PCA)表明,黑鳃梅童和小黄鱼摄食器官的形态特征与皮氏叫姑鱼存在一定的差异。     

Distribution and feeding habits of juvenile and young John's snapper Lutjanus johnii in the Matang mangrove estuary, west coast of Peninsular Malaysia

ABSTRACT:   The aim of the present paper was to provide some information on the distribution pattern and feeding habits of juvenile and young Lutjanus johnii in the Matang mangrove estuary on the west coast of Peninsular Malaysia. Sampling was carried out at five sites using otter trawl nets from October 1998 to January 2000. Ninety-three individuals of juvenile and young L. johnii were collected during the research period. The range in total length varied from 3.4 to 21.1 cm, and the gonads of all fish were at the immature stage. Fish were caught at the river mouth and neighboring sites in Matang at a water depth of 1.6–7.5 m, salinity of 12.4–28.3, and temperature of 27.3–31.6°C. Individuals fed mainly on Natantia and Mysidacea, although the type of food varied with size. Large-sized individuals fed mainly on Natantia, and small-sized individuals on Mysidacea.     

Composition and spatial organization of fish assemblages in the lower Guadiana basin, southern Iberia

Abstract— A survey of fish assemblages (composition and spatial organization) was made in the lower Guadiana basin (southern Iberia) during the summer of 1994. A total of 6937 specimens belonging to 18 species were collected in 44 channel units and 30 sites (i. c. a series of channel units), comprising all the freshwater species previously recorded in the area except the exotic Esox lucius and the endemic endangered cyprinid Anaecypris hispanica. The endemic cyprinids Chondrostoma lemmingii and Barbus sclateri were rarely encountered, whereas the exotic Lepomis gibbosus was the predominant species found. The lower Guadiana fish community changed in space from assemblages characterized by the high relative abundances of Leuciscus pyrenaicus , smaller size-classes of Barbus spp. and Tropidophoxinellus alburnoides (all Iberian endemisms), to assemblages characterized by the high relative abundances of L. gibbosus, Micropterus salmoides, Cichlasoma facetum (all exotic species) and the larger size-classes of Barbus comiza and Barbus microcephalus . The former assemblages used smaller (i. e., narrow and shallow) sites and channel units, usually in tributaries and closer to headwaters, with smaller L. pyrenaicus being dominant in sites located in the tributaries discharging to the brackish Guadiana. This group was also related to channel units rich in emergent macropthytes. The latter assemblages were related to the largest sites and channel units, typically found in the main river or in tributary sites far from the source. Besides these two groups, some species were associated to noticeable environmental conditions; Blennius fluviatilis to channel units with current velocity and heterogeneous substrate, typically found in the main river, and Cobitis paludica to channel units with heterogeneous substrate.