Distribution of early life history stages of fishes in selected pools of the Upper Mississippi River

Effective management of the fishery resources of the Upper Mississippi River and successful mitigation of the loss of critical habitat depend in part on an understanding of the reproductive and early life history requirements of the affected fishes. However, little is known about the use of nursery areas by fishes in the river. Of the nearly 130 species identified in the adult ichthyofauna, only a few are represented proportionally in the available data on early life stages because study designs have not included consideration of the early stages, collection gears have not adequately sampled the young, and eggs and larvae of some species are difficult to sample by conventional approaches. For the species collected, information is available on seasonal variations in total densities, composition, and catch among different habitat types. However, the data are most accurate for species with buoyant early life stages, such as freshwater drum (Aplodinotus grunniens) and gizzard shad (Dorosoma cepedianum). Eggs and larvae of freshwater drum dominate collections made in the main channel, whereas other larval fishes are usually most abundant in backwater habitats. The species found there usually deposit eggs on the substrate or on vegetation. Habitat preferences (as indicated by relative abundance) often shift as development proceeds and physical and behavioral changes occur in the larvae. Only limited information is available on the distribution of larvae within habitats, but it is clear that variations within habitats are significant.     

Life cycle of Gnathostoma nipponicum Yamaguti, 1941.

The life cycle of Gnathostoma nipponicum was examined by field survey and by experimental infection of animals with the larvae. Naturally infected larval G. nipponicum were found in loaches, catfish, and snakes. Experimentally, loaches, killifishes, frogs, salamanders, mice, and rats were successfully infected with the early third-stage larvae of G. nipponicum obtained from copepods (the first intermediate host), whereas snakes, quails, and weasels were not. Frogs, snakes, quails, and rats were experimentally infected with the advanced third-stage larvae (AdL3) from loaches. These results reveal that some species of fishes, amphibians and mammals can act as the second intermediate host and that some species of reptiles, birds and mammals can act as a paratenic host. The life cycle was completed in weasels, the definitive host, which were infected with AdL3 from loaches and started to evacuate eggs of G. nipponicun in faeces on days 65-90 postinfection.     

Intraspecific variation in diet, growth, and morphology of landlocked Galaxias maculatus during its larval period: the role of food availability and predation risk

Food availability and predation risk have been shown to affect phenotypes during early life history of fishes. Galaxias maculatus, a small fish widely distributed around the southern hemisphere, clearly exhibits a complex trade-off between feeding and predation avoidance during growth over the larval period. We studied the effect of different environmental variables on diet, growth, mortality, and morphology through field surveys and data revision in the literature for limnetic G. maculatus larvae in five oligotrophic lakes of Patagonia. Both number of food categories and prey ingested by larvae were directly related to zooplankton density. Larval growth rate was related with zooplankton density and temperature. Lakes with high zooplankton densities and low predation risk had larvae with deeper bodies and shorter caudal peduncles, while in lakes with less food and high predation risk larvae were slender with shallower bodies and longer peduncles. Food availability and predation risk seem to operate on the swimming performance of G. maculatus larvae through the slenderness of the body and the length of the caudal peduncle. The observed phenotypic variation in growth and morphology could be a key feature that has allowed this species to successfully colonize a wide variety of environments in the southern hemisphere.     

Polyploidy in fishes: patterns and processes

Fishes are the most speciose group of vertebrates, with more than 24 000 species. They are characterized by great diversity in ecology, morphology, life history, behaviour and physiology. Here, the phylogenetic patterns of orders in which polyploidy has been recorded are considered, with special reference to patterns of species richness and hybridization: these orders include such phylogenetically diverse taxa as the Lepidosireniformes (lungfish) and the Perciformes (perch). Examples, predominantly drawn from the Cyprinidae and Salmonidae, are used to illustrate attributes of polyploidy in fishes. It is concluded (i) that polyploidy may have been of considerable importance in the evolution of fishes, and (ii) that fishes, with their diverse life histories, represent a useful model system with which to test theories relating to the origin and consequences of polyploidy that have been derived from work on plants.  © 2004 The Linnean Society of London, Biological Journal of the Linnean Society , 2004, 82 , 431–442.     

Fish, Flows and Flood Plains: Links between Freshwater Fishes and their Environment in the Murray-Darling River System, Australia

Knowledge of the biology of native fishes of the Murray-Darling Basin is based largely on studies conducted under hatchery conditions and on a limited number of recreationally important species. From observations that increases in water level in aquaculture ponds initiate spawning in some species, and from limited studies of wild fishes and studies in overseas floodplain river systems, a perception has emerged of the importance of flooding and the flood plain in the life cycles of Murray-Darling fishes in general. However, there is little confirmatory evidence of the use of temporary floodplain habitats by larvae, juveniles or adults. The significance of in-channel habitats, especially for rearing, has received little attention. Murray-Darling fish species can be placed into three life history modes, based mainly on spawning style and time and developmental intervals of larvae at first feeding. Fish in each group may be able to take advantage of floods if the timing is right and prey are plentiful, however, the larvae of some species are able to recruit under non-flood conditions within the main river channel. This forms the basis of the low flow recruitment hypothesis, which attempts to explain why some species spawn during the warmest months and lowest flows and how they are able to recruit under these conditions. This hypothesis is then placed in the context of the current state of knowledge of the relationships between flow and the biology of Murray-Darling fishes, specifically cues for spawning, movement and recruitment. The lack of widespread evidence for floodplain use by any life history interval of fish may be due to a paucity of study, however, there are some fundamental factors, such as the predictability of timing and duration of high flow events as well as the lack of coincidence of high flows and high temperatures in some regions of the Basin, which may be important in determining the use of floodplain habitats by fish.     

Trophic relationships between the larvae of two freshwater mussels and their fish hosts

Freshwater mussels of the order Unionoida have life cycles that include larval attachment to and later metamorphosis on suitable host fishes. Information on the trophic relationship between unionoid larvae and their host fishes is scarce. We investigated the trophic interaction between fish hosts and encysted larvae of two species of freshwater mussels, Margaritifera margaritifera and Unio crassus, using stable isotope analyses of larvae and juvenile mussels as well as of host fish gill and muscle tissues before and after infestation. Due to different life histories and durations of host‐encystment, mass and size increase in M. margaritifera during the host‐dependent phase were greater than those of U. crassus. δ¹³C and δ¹⁵N signatures of juvenile mussels approached isotopic signatures of fish tissues, indicating a parasitic relationship between mussels and their hosts. Shifts were more pronounced for M. margaritifera, which had a five‐fold longer host‐dependent phase than U. crassus. The results of this study suggest that stable isotope analyses are a valuable tool for characterizing trophic relationships and life history strategies in host–parasite systems. In the case of unionoid mussels, stable isotopic shifts of the larvae are indicative of the nutritional versus phoretic importance of the host.     

长江口鳗苗网兼捕鱼类物种多样性及其群聚结构

为探明长江口鳗苗网兼捕鱼类的物种多样性及其群聚结构,文章分析了2017—2019年鳗苗汛期用定置张网采集的11870网次鱼类样本。结果显示,样本中包含兼捕鱼类114388尾,经鉴定有54种,隶属13目27科46属。其中,鲈形目占总种数的40.74%,海洋性、肉食性、底层和小型鱼类分别占总种数的44.44%、74.07%、70.37%和48.15%。拉氏狼牙虾虎鱼(Odontamblyopus lacepedii)为第一优势种,数量占比达77.07%;焦氏舌鳎(Cynoglossus joyneri)、刀鲚(Coilia nasus)和斑鰶(Konosirus punctatus)也是个别年份的优势种。根据各月份间鱼类的群聚差异可将3月和4月、1月和2月各组合成1个组,两者的主要特征种分别有5种和6种,主要分歧种有10种。兼捕鱼类的平均体长仅(73.77±38) mm,早期资源占总样本数的96.65%,许多是当地经济鱼类的幼体。样本中有鳗苗16470尾, 3年平均的兼捕损伤率7.58,高于6年前的损伤率,鳗苗捕捞对其他鱼类幼体的损伤应引起重视。     

Proposed life cycle of Ascarophis marina (Nematoda: Cystidicolidae) in Argentine waters

The life history of Ascarophis marina in Argentina is proposed on the basis of morphometric features of larval and adult specimens, as well as of trophic relationships among invertebrate and vertebrate hosts in the same geographic area. Adult and larval specimens of A. marina were found in the alimentary tract of the teleost fishes Parona signata (Carangidae) and Urophycis brasiliensis (Gadidae). Third-stage larvae ocurred in the shrimps Peisos petrunkevitchi (Sergestidae) and Artemesia longinaris (Penaeidae).     

The predation gauntlet: early post-settlement mortality in reef fishes

Most marine fishes have pelagic larvae that settle to benthic juvenile/adult habitats. Ecologists have argued that mortality rates are particularly high during the settlement transition, but relevant data have been sparse. Recently, researchers have used several novel techniques to estimate the magnitude of predation mortality during the settlement transition. We used meta-analysis to determine that for 24 taxonomically diverse species in geographically widespread locations, an estimated 55.7% (CI: 43.0–65.5%) of juveniles were consumed within 1–2 days of settlement. Such high mortality highlights this brief period as a key phase in the life history of fishes and supports the view that these communities are strongly influenced by predation. Additionally, we argue that because predators have such strong effects on juvenile survival, the population and community dynamics of reef fishes may be linked to human exploitation of reef predators.     

A review on the early life history and ecology of Japanese sea bass and implication for recruitment

Recruitment in marine fishes is regulated largely by the demographic changes that occur during the early life stages; therefore, a thorough understanding of early life stages is essential for predicting recruitment variability in fishes. Japanese sea bass (JSB), Lateolabrax japonicus, is a coastal marine fish distributed in East Asian coastal waters, and is regarded as highly important for commercial and recreational fisheries, for marine and brackish water aquaculture as well as for stock enhancement. JSB is a typical estuarine dependent temperate fish, which spawns in shelf areas and coastal embayments and the larvae and juveniles are dispersed and transported into shallow nearshore habitats and estuaries where they spend the early life. In this paper, we provide insight into the early life history and ecology of JSB through a revision of the available information and using the data we obtained from a relatively long-term research. We review and discuss the distribution and habitat use, food and feeding, age and growth, mortality and recruitment of larval and juvenile JSB in coastal waters around Japan. We extend our discussions in all available dimensions: habitat-specific, ontogenetic, and spatio-temporal, and highlight the importance of nursery habitats. We also discuss the implications of early life history for recruitment of JSB as well as the possible effects of climate change. At the end, we point out potential areas for future research.     

Life History of Chauliognathus lugubris (F.) (Coleoptera: Cantharidae) in Tasmanian Forests

Aspects of the life history of Chauliognathus lugubris , a predator of eggs and early stage larvae of the Eucalyptus leafbeetle, Chrysophtharta bimaculata , were studied in southern Tasmania. In the laboratory (ambient temperature 15-25°and artificial diet), the egg to adult period was about 10 months with seven larval stages. Advanced larvae (5th-7th instar) were collected in the field from soil litter during mid-winter. Adults were most common in the spring and early summer. with regular field collections suggesting adult longevity of 2-3 months. Based on the pattern of ovarian development of field-caught adults, in combination with the long larval development times, it appeared that C. lugubris has only one generation a year.     

Prepared for the future: A strong signal of evolution toward the adult benthic niche during the pelagic stage in Labrid fishes

The morphology of organisms reflects a balance between their evolutionary history, functional demands, and biomechanical constraints imposed by the immediate environment. In many fish species, a marked shift in the selection regime is evident when pelagic larvae, which swim and feed in the open ocean, settle in their adult benthic habitat. This shift is particularly dramatic in coral‐reef fishes, where the adult habitat is immensely complex. However, whether the adult trophic ecotype affects the morphology of early‐life stages is unclear. We measured a suite of 26 functional‐morphological traits in the head and body of larvae from an ontogenetic series of 16 labrid species. Using phylogenetic comparative methods, we reconstructed the location of adaptive peaks of larvae whose adults are associated with different trophic ecotypes. We found that the morphospace occupation in these larvae is largely driven by divergent adaptations to the adult benthic habitats. The disparity between adaptive peaks is achieved early and does not monotonically increase with size. Our findings thus refute the notion that larvae rapidly acquire the trophic‐specific traits during a metamorphic period immediately prior to settlement. This early specialization might be due to the highly complex musculoskeletal system of the head that cannot be rapidly modified.     

沈阳地区国槐尺蠖发生规律研究

通过室内饲养和田间观察,对国槐尺蠖Semiothisa cinerearia Bremer et Grey各虫态(成虫、卵、幼虫、蛹)特征进行了详细的描述。对国槐尺蠖的行为习性、生活史以及田间种群消长规律进行了深入的研究。研究结果表明,国槐尺蠖在沈阳一年发生3代,无世代重叠,以蛹在树下松软土壤中越冬。国槐尺蠖幼虫共有7龄,1～4龄取食量小,5龄以后食量大增,进入暴食期,取食量占全幼虫期的80%～90%,而且随着虫龄的增长,其存活率增加。国槐尺蠖幼虫发生期为5月到9月,6月上旬、中旬至7月下旬为幼虫为害盛期,9月以后种群呈递减趋势,老熟幼虫开始入土化蛹越冬。     

Life history evolution and comparative developmental biology of echinoderms

Evolutionary biologists studying life history variation have used echinoderms in experimental, laboratory, and field studies of life history evolution. This focus on echinoderms grew originally from the tradition of comparative embryology, in which echinoderms were central. The tools for obtaining and manipulating echinoderm gametes and larvae were taken directly from comparative embryological research. In addition, the comparative embryologists employed a diverse array of echinoderms, not a few model species, and this diversity has led to a broad understanding of the development, function, and evolution of echinoderm larvae. As a result, this branch of life history evolution has deep roots in comparative developmental biology of echinoderms. Here two main aspects of this relationship are reviewed. The first is a broad range of studies of fertilization biology, dispersal, population genetics, functional morphology, and asexual reproduction in which developmental biologists might take a keen interest because of the historical origins of this research in echinoderm comparative embryology. The second is a similarly broad variety of topics in life history research in which evolutionary biologists require techniques or data from developmental biology in order to make progress on understanding patterns of life history variation among echinoderm species and higher taxa. Both sets of topics provide opportunities for interaction and collaboration.     

Near-reef elemental signals in the otoliths of settling Pomacentrus amboinensis (Pomacentridae)

Coral Reefs - Settlement is a key life history transition for coral reef fishes, and how long a fish spends close to a reef prior to settlement is poorly understood. We used laser ablation...     

槐小卷蛾生物学研究

通过室内饲养和野外调察,明确了槐小卷Cydia trasias(Meyrick)在山东泰安的发生规律,结果表明:该虫在泰安1年3代,以幼虫蛀食国槐(Sophora japonicaL.)等槐属的叶柄及果荚,一头幼虫危害9～12个叶柄,群体爆发时造成大量叶柄脱落、秃枝、果荚变黑,影响国槐的观赏和经济价值。10月份以老熟幼虫在原蛀孔、树皮缝、果荚内越冬。     

Ontogenic migration of Pleuronectes flesus larvae in the eastern English Channel

Along the French coast of the eastern English Channel there is a strong separation in the hydrology, zooplankton community and ichthyoplankton assemblages, between a coastal ecosystem of continental influence and an offshore ecosystem of Atlantic influence. During April and May 1995, two surveys (60 stations) were conducted to describe the early life history of fishes in this area, and especially the influence of hydrodynamics on Pleuronectes flesus larval transfer from the spawning grounds to the nurseries. Ontogenic changes in larval distributions were described by variograms and path analysis. P. flesus eggs and young larvae were found in the southern offshore area. Their distributions were mainly influenced by sediment and cold temperature found in the central part of the Channel. Older larvae were found at more northern stations, showing a clumped distribution near estuaries, in areas of low salinity. Apparently, young stages of this species were transported from the south central spawning area to coastal waters by residual currents. Behavioural changes in older larvae facilitate the move to nurseries along the French coast.     

Re-colonization of Atlantic and Pacific rivers by anadromous fishes: linkages between life history and the benefits of barrier removal

The last two decades have seen a rapid increase in barrier removals on rivers of the Northern Hemisphere, often for the explicit purpose of expanding the abundance, spatial distribution, and life history diversity of migratory fishes. However, differences in life history such as seasonal timing of migration and reproduction, iteroparity versus semelparity, and the extent of natal homing are likely to affect the capacity for expansion and re-colonization by taxa such as alosines, lamprey, and salmonids. We first review some basic life history traits that may affect re-colonization by migratory fishes, and then present selected examples from Atlantic and Pacific basins to illustrate these patterns and their implications for the success of barrier removal as a measure to advance the goal of fish conservation. We conclude that diadromous fishes have the capacity to rapidly re-colonize newly available habitats, though the life history patterns of each species, the proximity to source populations in the same or nearby river systems, and the diversity of habitats available may control the patterns and rates of re-colonization.     

Kinship affects innate responses to a predator in bluegill Lepomis macrochirus larvae

Naïve kin groups and mixed-family groups of bluegill Lepomis macrochirus larvae were exposed to a novel predator cue. The larvae responded by increasing shoal cohesiveness in kin groups but not in mixed-family groups; moreover, larvae sired by males of the 'cuckolder' life history tended to have an enhanced ability to respond to direct cues of kinship v . larvae sired by males of the 'parental' life history, which instead appeared to respond to cues of life history rather than relatedness per se . The increased shoal cohesion among related individuals probably confers a survival benefit and indicates that the antipredatory shoaling response is innate in L. macrochirus .     

Adaptations of Cave Fishes with some Comparisons to Deep-sea Fishes

I provide my retrospective and prospective views on adaptations of cave fishes. I emphasize the history of my insights into cave adaptation from 45 years of research using surface, cave-spring, and cave species of amblyopsid fishes. My approach has been to use natural experiments and to always consider multiple hypotheses. To clarify evolutionary adaptations, I show the importance of a broad comparative approach which includes studies of morphology, metabolic physiology, foraging behavior, life history, and ecology. And I show that the most important agents of selection, of darkness and attendant low food supply, are best understood in the context of rigor, variability, and predictability. I also present my insights from what I consider the most insightful contributions on deep-sea fishes. The contributions are those of Marshall in studies of morphology in relation to energy economy of pelagic and benthic species, Childress in studies of physiological and biochemical adaptations with depth for pelagic species, and Koslow in studies on population biology and life history of bathybenthic and benthic sea-mount species. Compared to caves, I suggest that the extremes of metabolic and life history adaptations of deep-sea fish are explained by a longer evolutionary history and a much greater habitat range, food supply, and predation risk. Finally, I take a retrospective view of what we have learned about cave fishes. I discuss possible evolutionary mechanisms that can explain the trends with increasing cave adaptation in amblyopsid fishes, especially progenesis and the pleiotropic effects of the stress resistance syndrome. Finally, based on insights from deep-sea fishes, and emerging new techniques, I suggest what cave fish biologists should do in the future.