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.

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

scholarly journals Modelling the dispersal of riverine fish larvae: from a raster-based analysis of movement patterns within a racetrack flume to a rheoreaction-based correlated random walk (RCRW) model approach

2017 ◽  
Vol 74 (9) ◽  
pp. 1474-1489 ◽  
Author(s):  
Martin Glas ◽  
Michael Tritthart ◽  
Bernhard Zens ◽  
Hubert Keckeis ◽  
Aaron Lechner ◽  
...  
Keyword(s):  
Random Walk ◽  
Larval Fish ◽  
Fish Larvae ◽  
Movement Patterns ◽  
Release Site ◽  
Random Walk Model ◽  
Correlated Random Walk ◽  
Particle Tracing ◽  
Nursery Habitats ◽  
Chondrostoma Nasus

Recruitment of Chondrostoma nasus and similar fish species in rivers is related to spatiotemporal linkages between larval hatching and nursery habitats. Active swimming behaviour contradicts the assumption that passive particle tracing models can serve as a proxy for larval dispersal models. A racetrack flume with an inshore area of near-natural slope was created to observe individual larval trajectories. A new three-step, raster-based analysis was developed to distinguish four types of movement patterns: active upstream, active downstream, active–passive, and passive. Both larval developmental stage-specific and release site-specific occurrences of these movement patterns were experimentally found for nine flow velocity classes (≤0.225 m·s−1). These current-induced movement patterns, and evaluated durations within them, were used to develop a biased and correlated random walk model that includes rheoreaction — a key behavioural response of fish to flow within rivers. The study introduces the concept and application of a rheoreaction-based correlated random walk model, which coupled with a 3D hydrodynamic model, allows prediction of the spatiotemporal effects of various river discharges, morphologies, and restoration scenarios on larval fish dispersal.

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.

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.

The influence of discharge, current speed, and development on the downstream dispersal of larval nase (Chondrostoma nasus) in the River Danube

2018 ◽  
Vol 75 (2) ◽  
pp. 247-259 ◽  
Author(s):  
Aaron Lechner ◽  
Hubert Keckeis ◽  
Martin Glas ◽  
Michael Tritthart ◽  
Helmut Habersack ◽  
...  
Keyword(s):  
Developmental Stage ◽  
Release Site ◽  
Current Speed ◽  
Low Flow ◽  
Critical Conditions ◽  
Dispersal Patterns ◽  
Hydraulic Conditions ◽  
River Danube ◽  
Chondrostoma Nasus ◽  
Fish Activity

We investigated the mode (active versus passive) of larval downstream dispersal and its influencing factors in the nase carp (Chondrostoma nasus). Marked larvae (early and later stages), together with equivalent numbers of passive particles, were released in the main channel of the River Danube (Austria) at different flow (low, high) and current (over-critical, under-critical) conditions. Larvae and particles were recaptured with stationary nets at varying distances from release. We assumed that differences in the spatial dispersal patterns between larvae and particles were due to fish activity. We hypothesized that river discharge, developmental stage, current speed, and distance from release would influence these differences. We found that activity was independent of developmental stage or current speed at release, although activity was higher during low flow conditions. It may be that larvae deliberately enter the current during low flow, because the hydraulic conditions facilitate active dispersal. Furthermore, activity was greatest near the release site. This might be due to an intrinsically greater activity when fish are placed into novel surroundings or a result of rheoreaction. The discharge-dependent dispersal patterns observed represent an important ecological link between flow and recruitment and demonstrate the importance of inshore conditions for the early life stages of fish in large rivers, especially with regard to river modification and restoration schemes.

The diversity and longitudinal changes of zooplankton in the lower course of a large, regulated European river (the lower Vistula River, Poland)

Biologia ◽  
2013 ◽  
Vol 68 (6) ◽  
Author(s):  
Paweł Napiórkowski ◽  
Teresa Napiórkowska
Keyword(s):  
Species Diversity ◽  
Zooplankton Community ◽  
Abundant Species ◽  
Main Channel ◽  
Brachionus Calyciflorus ◽  
Longitudinal Variation ◽  
Zooplankton Species ◽  
Larval Stages ◽  
Vistula River ◽  
Brachionus Angularis

AbstractThe diversity and longitudinal variation of zooplankton in the lower Vistula River were analyzed. Samples were taken from 40 stations located along a 272-km long section of the lower river course. During the study the unique technique of taking samples from “the same water” was used. The zooplankton community was dominated by rotifers and nauplii — larval stages of copepods. The most abundant species were: Brachionus angularis, Brachionus calyciflorus and Brachionus budapestiensis. The zooplankton species diversity in the main channel of the lower Vistula River was similar to other large European rivers; however, its abundance was lower. The diversity, abundance and biomass of potamoplankton steadily decreased downstream. This could be related both to scarcity of storage zones for potamoplankton development in the river due to the extensive regulation processes, and changes in hydrological conditions of the main channel (by the straightening of riverbed) where the samples were collected.

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.

Diel and tidal abundance of fish larvae in a barrier-estuary channel in New South Wales

2001 ◽  
Vol 52 (7) ◽  
pp. 995 ◽  
Author(s):  
T. Trnski
Keyword(s):  
Larval Fish ◽  
Fish Larvae ◽  
New South ◽  
New South Wales ◽  
Common Species ◽  
South Wales ◽  
Marine Source ◽  
Nursery Habitats ◽  
Current Flows ◽  
June July

In four 24-h series of ichthyoplankton sampling during winter (June–July) 1996 in Swansea Channel (which connects Lake Macquarie with coastal waters of central New South Wales, Australia) 3367 fish larvae representing at least 77 species were collected. The larval fish community clustered by sampling date and by diel phase. Diel phase had a stronger influence on abundance of more common taxa than did tide phase, and also most influence on community structure. For most taxa there was no difference in abundance between flood and ebb tides, regardless of the estuarine or marine source of the eggs and larvae. All but two of 16 common species were present in Swansea Channel throughout their entire larval stage. The sparids Acanthopagrus australis and Rhabdosargus sarbawere present in the channel only at settlement-competent sizes. These two species showed evidence of selective presence in the channel during a particular diel or tidal phase, with A. australis apparently preferring night-flood tides, which would aid migration to the estuarine nursery habitats in Lake Macquarie. The ability or inclination to escape the strong bi-directional flows in channels seems limited to only a few taxa that appear to respond to physical cues and tidal current flows.

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.

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