Feeding behaviour of larval Ambystoma mexicanum

2011 ◽  
Vol 32 (4) ◽  
pp. 509-517 ◽  
Author(s):  
Diego de Jesus Chaparro-Herrera ◽  
S. Nandini ◽  
S.S.S. Sarma ◽  
Luis Zambrano
Keyword(s):  
Prey Species ◽  
Fish Larvae ◽  
Natural Habitat ◽  
Ambystoma Mexicanum ◽  
Larval Stages ◽  
Conservation Effort ◽  
Consistent Increase ◽  
Zooplankton Consumption ◽  
Oviparous Fish ◽  
Heterocypris Incongruens

Abstract The Axolotl, Ambystoma mexicanum, endemic to the freshwater lakes, Xochimilco and Chalco in Mexico City, feeds on zooplankton during its larval stages. We evaluated the functional response over eight weeks of A. mexicanum fed different prey items found in its natural habitat (rotifers: Brachionus havanaensis, B. calyciflorus, B. rubens and Plationus patulus; cladocerans: Moina macrocopa, Macrothrix triserialis, Alona glabra and Simocephalus vetulus; and ostracods: Heterocypris incongruens). Zooplankton consumption by A. mexicanum varied in relation to the prey species and age of the larvae. Unlike oviparous fish larvae which often feed preferentially on rotifers in the first few weeks, A. mexicanum larvae fed more on cladocerans and ostracods. Among the cladocerans offered, larval A. mexicanum consumed higher numbers of M. triserialis and M. macrocopa. Feeding on the largest cladoceran tested, S. vetulus, increased after the fifth week. There was a consistent increase in the number of ostracods Heterocypris incongruens, consumed with age, from 4 to 169 prey per larva over eight weeks. The results are discussed with relation to the importance of zooplankton diet in conservation effort of this endangered species in Lake Xochimilco.

Fickian Transport and the Dispersal of Fish Larvae in Estuaries

1982 ◽  
Vol 39 (8) ◽  
pp. 1150-1163 ◽  
Author(s):  
L. Fortier ◽  
W. C. Leggett
Keyword(s):  
Vertical Distribution ◽  
Fish Larvae ◽  
Sampling Period ◽  
Clupea Harengus ◽  
Tidal Mixing ◽  
Larval Abundance ◽  
Lawrence Estuary ◽  
Larval Stages ◽  
Diel Vertical Migrations ◽  
Average Size

We studied the regulation of ichthyoplankton dispersion in the two-layer circulation of the St. Lawrence upper estuary by determining larval abundance and vertical distribution during high frequency sampling at three stations in May, June, and July, 1979. Monthly variations in capelin (Mallotus villosus) and Atlantic herring (Clupea harengus harengus) abundance were in agreement with the seasonal trends previously reported. Capelin larvae were concentrated in the surface layer, a situation which resulted in seaward drift. No significant growth was observed over the 60-d sampling period indicating continuous recruitment to, and removal from, the sampling area. Herring larvae were concentrated in the deep layer and were carried landward. The average size of herring larvae increased from the downstream to the upstream stations. Short-term fluctuations in the abundance and vertical distribution of the two species were interpreted in terms of the Fickian representation of transport for partially mixed estuaries. The major source of variation in abundance, at a given station, was the tidal advection of horizontal gradients. Capelin larvae and herring larvae smaller than 10 mm did not actively cross the pycnocline and were not submitted to the diffusive effect of the vertical current shear. The dispersal of these larvae was apparently passive. Herring larvae larger than 10 mm performed diel vertical migrations across the pycnocline and were dispersed in the horizontal plane at a faster rate than a passive contaminant of the environment. We conclude that the Fickian approach can be profitably applied to studies of dispersal and mortality of early larval stages of fish in estuaries.Key words: ichthyoplankton, St. Lawrence estuary, dispersion, transport, vertical distribution, diel migrations, variability, abundance, tidal mixing, Fickian

Kinematics and efficiency of steady swimming in adult axolotls (Ambystoma mexicanum)

1997 ◽  
Vol 200 (13) ◽  
pp. 1863-1871 ◽  
Author(s):  
K D'Août ◽  
P Aerts
Keyword(s):  
Swimming Speed ◽  
High Speed ◽  
Natural Habitat ◽  
Total Body Length ◽  
Ambystoma Mexicanum ◽  
The Body ◽  
Entire Body ◽  
Amplitude Profile ◽  
Wide Range ◽  
Tail Tip

The kinematics of steady swimming at a wide range of velocities was analysed using high-speed video recordings (500 frames s-1) of eight individuals of Ambystoma mexicanum swimming through a tunnel containing stationary water. Animals in the observed size range (0.135­0.238 m total body length) prefer to swim at similar absolute speeds, irrespective of their body size. The swimming mechanism is of the anguilliform type. The measured kinematic variables ­ the speed, length, frequency and amplitude (along the entire body) of the propulsive wave ­ are more similar to those of anguilliform swimming fish than to those of tadpoles, in spite of common morphological features with the latter, such as limbs, external gills and a tapering tail. The swimming speed for a given animal size correlates linearly with the tailbeat frequency (r2=0.71), whereas the wavelength and tail-tip amplitude do not correlate with this variable. The shape of the amplitude profile along the body, however, is very variable between the different swimming bouts, even at similar speeds. It is suggested that, for a given frequency, the amplitude profile along the body is adjusted in a variable way to yield the resulting swimming speed rather than maintaining a fixed-amplitude profile. The swimming efficiency was estimated by calculating two kinematic variables (the stride length and the propeller efficiency) and by applying two hydrodynamic theories, the elongated-body theory and an extension of this theory accounting for the slope at the tail tip. The latter theory was found to be the most appropriate for the axolotl's swimming mode and yields a hydromechanical efficiency of 0.75±0.04 (mean ± s.d.), indicating that Ambystoma mexicanum swims less efficiently than do anuran tadpoles and most fishes. This can be understood given its natural habitat in vegetation at the bottom of lakes, which would favour manoeuvrability and fast escape.

scholarly journals Molecular identification of Auxis spp. larvae (Pisces: Scombridae) from the Gulf of California: Solving morphological identification limits

2018 ◽  
Vol 53 (2) ◽  
pp. 157 ◽  
Author(s):  
María J. Ochoa-Muñoz ◽  
Noé Díaz-Viloria ◽  
Laura Sánchez-Velasco ◽  
Sylvia P. A. Jiménez-Rosenberg ◽  
Ricardo Pérez-Enríquez
Keyword(s):  
Molecular Identification ◽  
Gulf Of California ◽  
Fish Larvae ◽  
Morphological Characteristics ◽  
Species Level ◽  
Morphological Identification ◽  
Larval Stages ◽  
Marine Fish Larvae ◽  
Coi Sequences ◽  
First Time

The larvae of the Auxis genus are abundant in the Gulf of California during summer; however, their identification to the species level by morphological methods is a challenge. The goal of this study was to identify A. thazard and A. rochei larvae for first time, through molecular markers using COI sequences of mtDNA, and look for distinctive morphological characteristics between species, mainly in pigmentation patterns. Larvae were obtained by zooplankton tows in 3 oceanographic cruises in the southern Gulf of California and adjacent waters. The presence of A. thazard and A. rochei larvae was genetically confirmed. The sequences of 7 larvae showed genetic divergences lower than 1% when were compared to sequences of A. thazard adults, while 15 larvae showed genetic divergences lower than 2% when where compared to sequences of A. rochei adults. Genetic divergences between both Auxis species were higher than 2%. These results suggest the spawning of both species in the Gulf of California. On the other hand, pigmentation patterns and morphometric characteristics, in all larval stages, did not permit the secure differentiation between species. Thus, the use of molecular identification by COI is recommended to identify Auxis larvae to the species level, as well as in other marine fish larvae collected in other regions of the world, that have identification troubles.

Materials on multicellular parasites fauna of the ruffe Gymnocephalus cernuus Linnaeus, 1758 (Pisces: Percidae) from the Saratov water basin

2016 ◽  
Vol 3 (1) ◽  
pp. 16-23 ◽  
Author(s):  
Минеева ◽  
O. Mineeva
Keyword(s):  
Natural Habitat ◽  
Parasite Fauna ◽  
Middle Part ◽  
Reservoir Host ◽  
The Body ◽  
Infection Rates ◽  
Saratov Reservoir ◽  
Gymnocephalus Cernuus ◽  
Larval Stages ◽  
Nicolla Skrjabini

Objective of research. Data on the species composition of the fauna of multicellular parasites and the infection rates of the pope ruffe Gymnocephalus cernuus Linnaeus, 1758 from Mordovian floodplain of the Saratov reservoir (the middle part) are pesented. Materials and methods. 53 ruffe individuals were investigated in spring and summer 2012 – 2015 by incomplete parasitological post-mortem examination (Bykhovskaya-Pavlovskaya, 1985). 19 species of multicellular parasites belonging to 7 classes: Monogenea - 1, Cestoda - 1, Trematoda - 11, Nematoda - 3, Acanthocephala - 1, Bivalvia - 1, Crustacea – 1 were registered. The largest group are flukes; more than half of species (8) are larval forms, which is the result of bottom living of the host. The significant diversity of larval stages of helminths (8 species of trematodes and 2 species of nematodes) shows the involvement of the ruffe as an intercalary, supplementary and/or reservoir host in the circulation of parasites in fish, birds and mammals. 7 species of parasites infest the ruffe on the food chain; 12 species – using the active infestation way. Results and discussion. The studied parasite fauna contains one species narrowly specific for the ruffe (monogenea D. amphibothrium (Wagener, 1857) and 2 species typical for percoid fishes (cestoda Proteocephalus percae (Müller, 1780) and trematoda Bunodera luciopercae (Müller, 1776). 2 alien species Nicolla skrjabini (Iwanitzky, 1928) (marita) and Apophallus muehlingi (Jägerskiöld, 1898) (mtc.) whose natural habitat is limited by the rivers of the Azov-Black Sea and Baltic Sea were registered in the fauna of multicellular parasites of the ruffe from the Saratov reservoir. The most common ruffe parasites are Diplostomum and Ichthyocotylurus metacercariae metacercaria infesting fish by penetrating through the body covers. These metacercariae as well as Apophallus muehlingi metacercariae are pathogenic to fish.

scholarly journals Coral reef fish populations can persist without immigration

2015 ◽  
Vol 282 (1819) ◽  
pp. 20151311 ◽  
Author(s):  
Océane C. Salles ◽  
Jeffrey A. Maynard ◽  
Marc Joannides ◽  
Corentin M. Barbu ◽  
Pablo Saenz-Agudelo ◽  
...  
Keyword(s):  
Reproductive Success ◽  
Reef Fish ◽  
Egg Production ◽  
Fish Larvae ◽  
Sampling Period ◽  
Mortality Rates ◽  
Island Population ◽  
Larval Stages ◽  
Empirical Estimates ◽  
Annual Mortality

Determining the conditions under which populations may persist requires accurate estimates of demographic parameters, including immigration, local reproductive success, and mortality rates. In marine populations, empirical estimates of these parameters are rare, due at least in part to the pelagic dispersal stage common to most marine organisms. Here, we evaluate population persistence and turnover for a population of orange clownfish, Amphiprion percula , at Kimbe Island in Papua New Guinea. All fish in the population were sampled and genotyped on five occasions at 2-year intervals spanning eight years. The genetic data enabled estimates of reproductive success retained in the same population (reproductive success to self-recruitment), reproductive success exported to other subpopulations (reproductive success to local connectivity), and immigration and mortality rates of sub-adults and adults. Approximately 50% of the recruits were assigned to parents from the Kimbe Island population and this was stable through the sampling period. Stability in the proportion of local and immigrant settlers is likely due to: low annual mortality rates and stable egg production rates, and the short larval stages and sensory capacities of reef fish larvae. Biannual mortality rates ranged from 0.09 to 0.55 and varied significantly spatially. We used these data to parametrize a model that estimated the probability of the Kimbe Island population persisting in the absence of immigration. The Kimbe Island population was found to persist without significant immigration. Model results suggest the island population persists because the largest of the subpopulations are maintained due to having low mortality and high self-recruitment rates. Our results enable managers to appropriately target and scale actions to maximize persistence likelihood as disturbance frequencies increase.

Movement patterns and rheoreaction of larvae of a fluvial specialist (nase, Chondrostoma nasus): the role of active versus passive components of behaviour in dispersal

2018 ◽  
Vol 75 (2) ◽  
pp. 193-200 ◽  
Author(s):  
Bernhard Zens ◽  
Martin Glas ◽  
Michael Tritthart ◽  
Helmut Habersack ◽  
Hubert Keckeis
Keyword(s):  
Current Velocity ◽  
Water Movement ◽  
Fish Larvae ◽  
Movement Patterns ◽  
Swimming Activity ◽  
Natural Habitats ◽  
Larval Stages ◽  
Larval Behaviour ◽  
Upstream Direction

The dispersal of fish larvae in rivers might result from water movement but also from larval behaviour. Although potentially crucial for dispersion, knowledge of the role of behaviour is still fragmentary. This study intends to contribute to the question of how riverine fish larvae drift or move. All dispersal-relevant movement patterns of larvae of a characteristic rheophilic species were analyzed based on the parameters (i) swimming activity, (ii) direction of movement, and (iii) the orientation towards the current vector. Experiments were conducted in a novel flume mesocosm at three different flow scenarios covering the current velocity range of natural habitats. Mean current velocities in these scenarios were under, near, and over the “critical current velocity”, above which fish larvae are not able to constantly hold their position in the water column. Three consecutive larval stages were tested to account for possible ontogenetic shifts in movement behaviour, both during the day and at night. Our results strongly suggest that the assumption of mainly passively drifting larvae has to be refused; in total, 92.6% of all observed movement events were characterized by swimming activity and directed orientation, whereas only 7.4% could be assigned to passive drift. During downstream movement, a significant portion of movement events (57.1%) was attributed to larvae that orientated in an upstream direction and performed active swimming movements.

Estuarine Ichthyoplankton Ecology in Relation to Hydrology and Zooplankton Dynamics in salt-wedge Estuary

1996 ◽  
Vol 47 (2) ◽  
pp. 99 ◽  
Author(s):  
GM Newton
Keyword(s):  
Water Temperature ◽  
Fish Larvae ◽  
River Estuary ◽  
Extended Period ◽  
Salt Wedge ◽  
Larval Stages ◽  
Black Bream ◽  
Stable Conditions ◽  
Maximum Water Temperature ◽  
High Concentrations

The ichthyoplankton assemblage of the Hopkins River estuary, Victoria, was dominated by estuarine taxa that included demersal (goby, gudgeon) and pelagic (black bream, estuary perch, anchovy) species. The two seasonal peaks in fish larvae abundance were related to (1) the spring/summer zooplankton increase that occurred after flooding of the estuary and was comprised predominantly of copepod nauplii, thereby providing a good prey field for very young fish larvae, and (2) the autumn zooplankton maxima, which would provide a wide selection of copepod stages and meroplankton and promote dietary partitioning and flexibility among older larval stages. The two peaks in fish larvae abundance occurred well before and well after the attainment of maximum water temperature in the estuary. Goby, gudgeon, estuary perch and anchovy larvae were in the plankton over an extended period coinciding with the more stable conditions of salt-wedge presence and maximum zooplankton densities. The spawning of black bream and anchovies in the estuary was clearly related to physical conditions, such as salinity and water temperature, and habitat-although spawning of both species also occurred at times of high concentrations of potential prey organisms for their larvae. Adults of all the above fish species appear to have evolved spawning strategies that are adapted to the average hydrological and biological conditions in the estuary that would lead to the enhanced survival of their larvae. With the exception of the black bream, it appears that a ubiquitous and prolonged rather than a synchronous and confined spawning strategy is more widely used by estuarine-spawning fishes in the Hopkins River estuary. This type of spawning strategy, combined with the generally high density of food available to fish larvae in estuaries, suggests that the match-mismatch hypothesis of Cushing may be less relevant in the estuarine than in the marine environment.

scholarly journals Shoreline configurations affect dispersal patterns of fish larvae in a large river

2013 ◽  
Vol 71 (4) ◽  
pp. 930-942 ◽  
Author(s):  
Aaron Lechner ◽  
Hubert Keckeis ◽  
Elisabeth Schludermann ◽  
Franz Loisl ◽  
Paul Humphries ◽  
...  
Keyword(s):  
Fish Larvae ◽  
Local Population ◽  
Sampling Period ◽  
Large River ◽  
Main Channel ◽  
Dispersal Patterns ◽  
Larval Stages ◽  
Nursery Habitats ◽  
Chondrostoma Nasus ◽  
Gravel Bar

Abstract The dispersal patterns of marked larvae of the nase carp (Chondrostoma nasus L.) were observed alongside dissimilar shoreline configurations in the main channel of the free-flowing Austrian Danube and compared with those of floating particles to investigate the mode of dispersal (active–passive). Individuals of different larval stages and floats at similar densities were released at an artificial rip-rap with groynes and a rehabilitated gravel bar. In both habitats, marked individuals were recaptured during the sampling period of 4 d after release. Relevant shoreline attributes for larval dispersal, such as the accessibility of nursery habitats, connectivity between adjacent habitats, and retention potential, were more pronounced at the gravel bar than at the rip-rap. At the gravel bar, larvae moved upstream and downstream within the connected bankside nurseries and displayed longer residence times. Larvae settled in groyne fields along the rip-rap as well; however, longitudinal dispersal was disrupted by groynes, forcing larvae to enter the main channel. Rather than settling in subsequent groyne fields, we assume that these larvae are displaced downstream and potentially lost from the local population.

scholarly journals The Range of Prey Size of the Royal Bengal Tiger of Sundarbans

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Subrat Mukherjee ◽  
Neera Sen Sarkar
Keyword(s):  
Prey Species ◽  
Prey Availability ◽  
Natural Habitat ◽  
Secondary Data ◽  
Relative Number ◽  
Second Phase ◽  
Data Sets ◽  
Significant Difference ◽  
Bengal Tiger ◽  
The Difference

Relatively little is known about the feeding habit of the Royal Bengal Tiger of Sundarbans and the relative biomass of individual prey base species that the predator consumes during each kill. This is the first attempt to collect such data from the study area. Data sets of two phases have been used. Identification of undigested remains of 214 tiger scat samples was carried out. A comparison with Sundarbans tigers in zoo has been made. In its natural habitat, the tiger consumes more of spotted deer, followed by wild boar, rhesus monkey, and water monitor. Though the tiger consumes a relatively low proportion of small prey species to meet its dietary requirements, it gains importance in the present perspective. Significant increase is noted in the relative number of prey species consumed in the second phase, which correlates well with increased prey availability. Hypotheses formulated to find the difference in prey biomass and relative number of prey consumed have been tested statistically. A significant difference in terms of relative number of prey consumed only was derived which has been qualitatively correlated with the positive effect of increased vigilance, as revealed by secondary data, on conserving tiger habitat vis-a-vis the increased prey availability in Sundarbans.

Home range and activity patterns measured with GPS collars in spotted-tailed quolls

2015 ◽  
Vol 63 (6) ◽  
pp. 424 ◽  
Author(s):  
Gerhard Körtner ◽  
Nerida Holznagel ◽  
Peter J. S. Fleming ◽  
Guy Ballard
Keyword(s):  
Sexual Dimorphism ◽  
Home Range ◽  
Natural Habitat ◽  
Activity Patterns ◽  
Home Ranges ◽  
Population Densities ◽  
Gps Collars ◽  
Daytime Activity ◽  
Unidirectional Movement ◽  
Conservation Effort

The spotted-tailed quoll (Dasyurus maculatus) is the largest marsupial carnivore on mainland Australia. It usually occurs at relatively low population densities and its cryptic nature makes it exceedingly difficult to observe in its natural habitat. On the mainland the species is also listed as nationally endangered and more information is needed to direct any meaningful conservation effort. In this study we aimed to elucidate quolls’ spatial requirements and activity patterns using GPS collars on 10 males and 4 females. Quolls were predominantly nocturnal but some individuals showed pronounced daytime activity. There was no apparent seasonal shift in the timing of activity. The movement of quolls appeared to be confined to home ranges that were relatively large for predators of their size. Furthermore, males used home ranges about three times as large as that of the smaller females. There appeared to be some spatial segregation between not only females, which have been considered territorial, but also males. Overall, it is likely that the larger areas used by males is partly caused by the sexual dimorphism in body mass that entails differences in prey requirements and spectrum, but probably is also a function of a promiscuous mating system. All of these could explain the observed more unidirectional movement and larger distances travelled per day by males.

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