scholarly journals Perspectives on Larval Behaviour in Biophysical Modelling of Larval Dispersal in Marine, Demersal Fishes

Oceans ◽  
2020 ◽  
Vol 2 (1) ◽  
pp. 1-25
Author(s):  
Jeffrey M. Leis
Keyword(s):  
Fish Larvae ◽  
Behavioural Change ◽  
Larval Fishes ◽  
Larval Behaviour ◽  
Key Issues ◽  
Modelling Effort ◽  
Validation Research ◽  
Vertical Positioning ◽  
Study Species ◽  
Demersal Fishes

Biophysical dispersal models for marine fish larvae are widely used by marine ecologists and managers of fisheries and marine protected areas to predict movement of larval fishes during their pelagic larval duration (PLD). Over the past 25 years, it has become obvious that behaviour—primarily vertical positioning, horizontal swimming and orientation—of larvae during their PLD can strongly influence dispersal outcomes. Yet, most published models do not include even one of these behaviours, and only a tiny fraction include all three. Furthermore, there is no clarity on how behaviours should be incorporated into models, nor on how to obtain the quantitative, empirical data needed to parameterize models. The PLD is a period of morphological, physiological and behavioural change, which presents challenges for modelling. The present paper aims to encourage the inclusion of larval behaviour in biophysical dispersal models for larvae of marine demersal fishes by providing practical suggestions, advice and insights about obtaining and incorporating behaviour of larval fishes into such models based on experience. Key issues are features of different behavioural metrics, incorporation of ontogenetic, temporal, spatial and among-individual variation, and model validation. Research on behaviour of larvae of study species should be part of any modelling effort.

Temporal patterns in distributions of tropical fish larvae on the North West Shelf of Australia

2004 ◽  
Vol 55 (5) ◽  
pp. 473 ◽  
Author(s):  
A. Sampey ◽  
M. G. Meekan ◽  
J. H. Carleton ◽  
A. D. McKinnon ◽  
M. I. McCormick
Keyword(s):  
Southern Oscillation ◽  
Fish Larvae ◽  
Early Stage ◽  
Larval Survival ◽  
Zooplankton Biomass ◽  
Tropical Fish ◽  
North West ◽  
Larval Fishes ◽  
The North ◽  
Abundance And Diversity

Information on the temporal distributions of tropical fish larvae is scarce. Early stage larval fishes were sampled using towed bongo plankton nets at sites on the southern North West Shelf of Australia (21°49′S, 114°14′E), between October and February of 1997/98 and 1998/99. The first summer was characterised by El Niño–Southern Oscillation-driven upwelling and high primary productivity, whereas in the second summer water temperatures were warmer and primary production was lower. Benthic percoid shorefishes dominated surface assemblages in both summers and this pattern may be typical of tropical shelf environments.The abundance and diversity of larval fishes were lowest in October and increased from November through to February. Assemblages displayed weak cross-shelf patterns, with a few taxa being more abundant at inshore sites (e.g. monacanthids), whereas others were more abundant offshore (e.g. scombrids). Although the composition of assemblages remained relatively consistent, many taxa (e.g. pomacentrids and carangids) showed differences in abundance between summers. Multivariate analyses found no relationships between abundance patterns of larval fishes and biophysical variables, such as temperature, salinity, and zooplankton biomass. Thus, seasonal changes in abundance may reflect differences in the spawning activities of adult fishes and/or larval survival.

scholarly journals Effects of climate change on fish reproduction and early life history stages

2011 ◽  
Vol 62 (9) ◽  
pp. 1015 ◽  
Author(s):  
Ned W. Pankhurst ◽  
Philip L. Munday
Keyword(s):  
Climate Change ◽  
Elevated Temperatures ◽  
Endocrine System ◽  
Developmental Rate ◽  
Early Life History ◽  
Egg Survival ◽  
Life History Stages ◽  
Larval Fishes ◽  
Larval Behaviour ◽  
Temperature Ranges

Seasonal change in temperature has a profound effect on reproduction in fish. Increasing temperatures cue reproductive development in spring-spawning species, and falling temperatures stimulate reproduction in autumn-spawners. Elevated temperatures truncate spring spawning, and delay autumn spawning. Temperature increases will affect reproduction, but the nature of these effects will depend on the period and amplitude of the increase and range from phase-shifting of spawning to complete inhibition of reproduction. This latter effect will be most marked in species that are constrained in their capacity to shift geographic range. Studies from a range of taxa, habitats and temperature ranges all show inhibitory effects of elevated temperature albeit about different environmental set points. The effects are generated through the endocrine system, particularly through the inhibition of ovarian oestrogen production. Larval fishes are usually more sensitive than adults to environmental fluctuations, and might be especially vulnerable to climate change. In addition to direct effects on embryonic duration and egg survival, temperature also influences size at hatching, developmental rate, pelagic larval duration and survival. A companion effect of marine climate change is ocean acidification, which may pose a significant threat through its capacity to alter larval behaviour and impair sensory capabilities. This in turn impacts on population replenishment and connectivity patterns of marine fishes.

scholarly journals A conventional approach for comparing vertical reference frames

2012 ◽  
Vol 2 (4) ◽  
pp. 319-324
Author(s):  
C. Kotsakis
Keyword(s):  
Reference Frames ◽  
Optimal Estimation ◽  
Transformation Model ◽  
Practical Implementation ◽  
Height Determination ◽  
Vertical Datum ◽  
Key Issues ◽  
Perturbation Parameters ◽  
Physical Height ◽  
Vertical Positioning

AbstractA conventional transformation model between different realizations of a vertical reference system is an important tool for geodetic studies related to precise vertical positioning and physical height determination. Its fundamental role is the evaluation of the consistency for colocated vertical reference frames that are obtained from different observation techniques, data sources or optimal estimation strategies in terms of an appropriate set of “vertical datum perturbation” parameters. Our scope herein is to discuss a number of key issues related to the formulation of such a transformation model and to present some simple examples from its practical implementation in the comparison of existing vertical frames over Europe.

scholarly journals Hydrodynamic regime drives flow reversals in suction feeding larval fishes during early ontogeny

2019 ◽  
Author(s):  
Krishnamoorthy Krishnan ◽  
Asif Shahriar Nafi ◽  
Roi Gurka ◽  
Roi Holzman
Keyword(s):  
Numerical Simulations ◽  
High Speed ◽  
Prey Capture ◽  
Sparus Aurata ◽  
Larval Fish ◽  
Fish Larvae ◽  
Numerical Models ◽  
Hydrodynamic Regime ◽  
Suction Feeding ◽  
Larval Fishes

AbstractFish larvae are the smallest self-sustaining vertebrates. As such, they face multiple challenge that stem from their minute size, and from the hydrodynamic regime in which they dwell. This regime of intermediate Reynolds numbers (Re) was shown to affect the swimming of larval fish and impede their ability to capture prey. Numerical simulations indicate that the flow fields external to the mouth in younger larvae result in shallower spatial gradients, limiting the force exerted on the prey. However, observations on feeding larvae suggest that failures in prey capture can also occur during prey transport, although the mechanism causing these failures is unclear. We combine high-speed videography and numerical simulations to investigate the hydrodynamic mechanisms that impede prey transport in larval fishes. Detailed kinematics of the expanding mouth during prey capture by larval Sparus aurata were used to parameterize age-specific numerical models of the flows inside the mouth. These models reveal that, for small larvae that slowly expand their mouth, not all the fluid that enters the mouth cavity is expelled through the gills, resulting in flow reversal at the mouth orifice. This efflux at the mouth orifice was highest in the younger ages, but was also high (>8%) in slow strikes produced by larger fish. Our modeling explains the observations of “in-and-out” events in larval fish, where prey enters the mouth but is not swallowed. It further highlights the importance of prey transport as an integral part in determining suction feeding success.

Fine-scale larval fish distributions and predator-prey dynamics in a coastal river-dominated ecosystem

2020 ◽  
Vol 650 ◽  
pp. 37-61 ◽  
Author(s):  
KE Axler ◽  
S Sponaugle ◽  
C Briseño-Avena ◽  
F Hernandez ◽  
SJ Warner ◽  
...  
Keyword(s):  
Water Column ◽  
Fish Larvae ◽  
Spatial Scales ◽  
Wind Forcing ◽  
Strong Wind ◽  
Fine Scale ◽  
High Discharge ◽  
Predator Prey ◽  
Larval Fishes ◽  
Multiple Pulses

River plumes discharging into continental shelf waters have the potential to influence the distributions, predator-prey relationships, and thus survival of nearshore marine fish larvae, but few studies have been able to characterize the plume environment at sufficiently fine scales to resolve the underlying mechanisms. We used a high-resolution plankton imaging system and a sparse convolutional neural network to automate image classification of larval fishes, their planktonic prey (calanoid copepods), and gelatinous planktonic predators (ctenophores, hydromedusae, and siphonophores) over broad spatial scales (km) and multiple pulses of estuarine water exiting Mobile Bay (Alabama, USA) into the northern Gulf of Mexico from 9-11 April 2016. Fine-scale (1 m) plankton distributions were examined to analyze predator-prey relationships across 3 distinct plume regimes that varied by degree of wind-forcing and mixing rates. In calm wind conditions, the water column was highly stratified, and fish larvae and zooplankton were observed aggregating in a region of river plume-derived hydrodynamic convergence. As winds strengthened, the water column was subjected to downwelling and highly turbulent conditions, and there was decreasing spatial overlap between larval fishes and their zooplankton prey and predators. Our results indicate that high-discharge plume regimes characterized by strong wind-forcing and turbulence can rapidly shift the physical and trophic environments from favorable to unfavorable for fish larvae. Multiple pathways for both nearshore retention and advective dispersal of fish larvae were also identified. Documenting this variability is a first step toward understanding how high discharge events and physical forcing can affect fisheries production in river-dominated coastal ecosystems worldwide.

Evaluation of in situ Enclosures for Larval Fish Studies

1987 ◽  
Vol 44 (1) ◽  
pp. 54-65 ◽  
Author(s):  
Yves de Lafontaine ◽  
William C. Leggett
Keyword(s):  
Larval Fish ◽  
Fish Larvae ◽  
Low Cost ◽  
Experimental Studies ◽  
Size Composition ◽  
Surrounding Water ◽  
Larval Fishes ◽  
Plastic Bags ◽  
Capelin Mallotus Villosus

Two in situ enclosure designs intended for use in larval fish studies were evaluated for their capability to reproduce and track the physical properties of the surrounding water and to maintain the behavioral characteristics of enclosed organisms. The enclosures, which were constructed of porous material, allowed near instantaneous response to natural variations in temperature, salinity, and dissolved oxygen at all depths. Phytoplankton biomass inside the enclosures was less variable than that observed outside and its size composition was related to the porosity of the material used. Particle sinking rates inside the enclosures were much lower than those previously reported for plastic bags, suggesting a higher degree of turbulence in our enclosures. Newly hatched larval capelin (Mallotus villosus) and Zooplankton stocked into the enclosures exhibited diel migration of amplitude similar to that observed in the field. Zooplankton were more homogeneously distributed than fish larvae although heterogeneity decreased at night for both taxa. Low cost, ease of handling, environmental reproducibility, and quality of replication provided by the enclosures make them particularly appropriate for replicated experimental studies of the interactions between larval fishes, their predators, and prey.

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.

Changing with the tides: fine-scale larval fish prey availability and predation pressure near a tidally modulated river plume

2020 ◽  
Vol 650 ◽  
pp. 217-238 ◽  
Author(s):  
K Swieca ◽  
S Sponaugle ◽  
C Briseño-Avena ◽  
MS Schmid ◽  
RD Brodeur ◽  
...  
Keyword(s):  
Imaging System ◽  
Prey Availability ◽  
Fish Larvae ◽  
River Plume ◽  
Fine Scale ◽  
River Plumes ◽  
Temporal Scales ◽  
Spatial Overlap ◽  
Larval Fishes ◽  
Spatio Temporal

Tidally controlled river plumes form distinct frontal boundaries that can alter the spatial distributions of larval fishes and their planktonic prey and predators. Variable in nature, they may expose larval fishes to different trophic environments over small spatio-temporal scales, with unknown consequences for survival and recruitment. In the northern California Current, the Columbia River Plume is strongly influenced by twice-daily freshwater injections that create a highly dynamic coastal environment. Using the In situ Ichthyoplankton Imaging System, we examined changes in the fine-scale horizontal and vertical distributions of larval fishes, their prey, and their predators over space and time (ebb/flood tide). In total, 6095 fish larvae and ~1.5 million prey/predator zooplankton were imaged and measured. Plume regions provided substantially higher concentrations of prey and enhanced spatial overlap between larval fishes and their prey relative to oceanic waters. The functionality of river plumes as a refuge from predators was less clear. Predator concentrations were also higher in plume regions, but overlap with larval fishes was taxon-specific and varied with the tide. Notably, regions of high zooplankton concentrations did not necessarily confer high spatial overlap on small scales (meters vertical, kms horizontal) relevant to trophic interactions. Surface salinity and chlorophyll a were the most important factors influencing the spatial overlap of zooplankton with larval fishes. In the vicinity of river plumes, larval fishes experience a diversity of unique prey and predator fields over short spatio-temporal scales, which likely contribute to variable growth and mortality patterns at much finer scales than previously thought.

Consequences of plume encounter on larval fish growth and condition in the Gulf of Mexico

2020 ◽  
Vol 650 ◽  
pp. 63-80 ◽  
Author(s):  
KE Axler ◽  
S Sponaugle ◽  
F Hernandez ◽  
C Culpepper ◽  
RK Cowen
Keyword(s):  
Gulf Of Mexico ◽  
Continental Shelf ◽  
Prey Capture ◽  
Larval Fish ◽  
Fish Larvae ◽  
Fish Growth ◽  
Frequency Distributions ◽  
Larval Fishes ◽  
River Estuarine ◽  
Anchoa Hepsetus

Freshwater input into nearshore continental shelf waters from coastal river-estuarine plumes can greatly alter the physical and trophic environments experienced by fish larvae. However, the biological consequences of plume encounter on larval fish survival remain equivocal, largely due to the extreme variability of these systems but also because traditional sampling techniques alone are too coarse to effectively characterize the dynamic biophysical environment at spatiotemporal scales relevant to individual larvae. Using a multidimensional approach, we simultaneously collected in situ imagery and net samples of larval fishes and zooplankton from the Mobile Bay plume (Alabama, USA) and ambient continental shelf waters during a high discharge event (8-11 April 2016). We measured the effects of plume encounter on growth and condition of larval striped anchovy Anchoa hepsetus and sand seatrout Cynoscion arenarius, 2 prominent nearshore species in the northern Gulf of Mexico. Size-frequency distributions of both species indicated that larger individuals were present in shelf waters but absent from plume waters. Otolith microstructure analysis revealed that recent growth of both focal species was significantly lower for plume-collected larvae during the last few days prior to capture. Furthermore, plume larvae were in poorer morphometric condition (skinnier at length) than their shelf counterparts, despite the fact that there were higher concentrations of zooplankton prey in plume water masses. Taken together, these results suggest that elevated prey concentrations do not necessarily translate to higher growth and condition. High turbulence and turbidity within the plume may physically inhibit the prey capture ability and feeding success of fish larvae.

scholarly journals Modelling larval fish navigation: the way forward

2013 ◽  
Vol 71 (4) ◽  
pp. 918-924 ◽  
Author(s):  
Erica Staaterman ◽  
Claire B. Paris
Keyword(s):  
Ocean Circulation ◽  
Large Scale ◽  
Larval Fish ◽  
Fish Larvae ◽  
Three Dimensional ◽  
Environmental Signals ◽  
Biophysical Models ◽  
Larval Behaviour ◽  
Sea Fish ◽  
Insight Into

Abstract Recent advances in high-resolution ocean circulation models, coupled with a greater understanding of larval behaviour, have increased the sophistication of individual-based, biophysical models used to study the dispersal of larvae in the sea. Fish larvae, in particular, have the ability to swim directionally and increasingly fast during ontogeny, indicating that they may not only disperse, but also migrate using environmental signals. How and when larvae use local and large-scale cues remains a mystery. Including three-dimensional swimming schemes into biophysical models is becoming essential to address these questions. Here, we highlight state-of-the-art modelling of vertical and horizontal migrations of fish larvae, as well as current challenges in moving towards more realistic larval movements in response to cues. Improved understanding of causes for orientation will provide insight into the evolutionary drivers of dispersal strategies for fish and marine organisms in general.

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