Vertical Migrations and Transport of Larval Fish in a Partially Mixed Estuary

1983 ◽  
Vol 40 (10) ◽  
pp. 1543-1555 ◽  
Author(s):  
L. Fortier ◽  
W. C. Leggett
Keyword(s):  
Vertical Distribution ◽  
Large Scale ◽  
Larval Fish ◽  
Fish Larvae ◽  
Longitudinal Velocity ◽  
Clupea Harengus ◽  
Vertical Position ◽  
Diel Vertical Migrations ◽  
Clupea Harengus Harengus ◽  
The Vertical Distribution

The effect of diel or semidiurnal vertical migrations on the horizontal dispersal of fish larvae in a partially mixed estuary, and the external stimuli triggering these migrations, were investigated. The vertical distribution of ichthyoplankton and microzooplankton was estimated at 1-h intervals for 129 h, at a fixed station of the St. Lawrence upper estuary. With increasing length, capelin (Mallotus villosus) larvae congregated closer to the surface. This resulted in a length-dependent acceleration of the seaward drift of this species. Larger capelin developed a weak but significant pattern of diel vertical migrations limited to the surface (0–20 m) layer. The average vertical position of early postlarval Atlantic herring (Clupea harengus harengus) was close to the depth of null longitudinal velocity. Vertical migrations about this average level followed a semidiurnal cycle which brought the postlarvae toward the surface during flood. This synchronization minimized seaward tidal drift linked to incursions within the surface layer. The large-scale cyclonic circulation prevailing at depth appears responsible for the maintenance of early postlarval herring in the upper estuary. Both the average depth and the semidiurnal migrations of this species were closely related to the vertical distribution of prey.

Small-Scale Covariability in the Abundance of Fish Larvae and Their Prey

1984 ◽  
Vol 41 (3) ◽  
pp. 502-512 ◽  
Author(s):  
L. Fortier ◽  
W. C. Leggett
Keyword(s):  
Large Scale ◽  
Larval Fish ◽  
Fish Larvae ◽  
Spatial Scales ◽  
Low Frequency ◽  
Clupea Harengus ◽  
Differential Mortality ◽  
Small Scale ◽  
Capelin Mallotus Villosus ◽  
Clupea Harengus Harengus

We studied the covariability in the abundance of larval fish and rnicrozooplankton at a fixed station of the St. Lawrence upper estuary. Hourly sampling during 129 h combined with net and tidal circulations allowed us to resolve spatial scales of approximately 2 km to several tens of kilometres. Low-frequency fluctuations in the abundance of larval capelin (Mallotus villosus) and larval Atlantic herring (Clupea harengus harengus) reflected the advection past the station of successive cohorts. Large-scale horizontal gradients in abundance and length were apparently formed at the emergence of the larvae from the spawning beds. The majority of capelin larvae we sampled had not yet completely exhausted their yolk reserves. There was no indication that differential mortality or active swimming had produced a concordance between the distribution of this species and the distribution of microzooplankton. Herring larvae resorbed their yolk sac and began mandatory exogenous feeding during the period of sampling. Tidal and subtidal patterns of variation in the abundance of this species and microzooplankton became significantly coherent after the resorption of the vitelline reserves. The possible mechanisms giving rise to coherence at these two different scales are considered in light of published information on the feeding behavior and swimming capacity of herring larvae.

scholarly journals Influence of the Seasonal Thermocline on the Vertical Distribution of Larval Fish Assemblages Associated with Atlantic Bluefin Tuna Spawning Grounds

Oceans ◽  
2021 ◽  
Vol 2 (1) ◽  
pp. 64-83
Author(s):  
Itziar Alvarez ◽  
Leif K. Rasmuson ◽  
Trika Gerard ◽  
Raul Laiz-Carrion ◽  
Manuel Hidalgo ◽  
...  
Keyword(s):  
Vertical Distribution ◽  
Fish Assemblages ◽  
Larval Fish ◽  
Fish Larvae ◽  
Bluefin Tuna ◽  
Vertical Position ◽  
Near Surface ◽  
Atlantic Bluefin Tuna ◽  
Seasonal Thermocline ◽  
The Vertical Distribution

Temperature is often an important variable influencing the vertical position of fish larvae in the water column. The same species may show different vertical distributions in areas with a strong near-surface seasonal thermocline compared to isothermal near-surface regions. In areas with a strong surface thermocline, tuna larvae show a significant preference for the near-surface warmer layers. Little is known regarding larval tuna vertical distribution in isothermal waters and on the vertical distribution of the associated larval fish assemblages. We conducted vertical stratified sampling using the same methodology and fishing device (MOCNESS) in the two major spawning areas of Atlantic bluefin tuna (BFT): western Mediterranean Sea (MED), characterized by a surface thermocline, and the Gulf of Mexico (GOM) which lacks thermal stratification. Tuna larvae occupied the upper 30 m in both areas, but the average larval depth distribution was consistently deeper in the GOM. In the MED, vertical distribution of larval fish assemblages was explained by temperature, and species such as BFT, Thunnus alalunga, and Ceratoscopelus maderensis, among others, coexist above the thermocline and are separated from species such as Cyclothone braueri and Hygophum spp. (found below the thermocline). In the GOM, the environmental correlates of the vertical distribution of the larvae were salinity and fluorescence. Mesopelagic taxa such as Ceratoscopelus spp. and Cyclothone spp., among others, had a shallower average distribution than Lampanyctus spp., Hygophum spp., and Myctophum spp.

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 ANALYSIS OF THE VERTICAL DISTRIBUTION OF THE ABUNDANCE OF SMALL PELAGIC FISH LARVAE IN THE GULF OF CALIFORNIA USING SUBMARINE VIDEOCAMERAS

2009 ◽  
Vol 24 (2) ◽  
pp. 153
Author(s):  
G. Aceves-Medina ◽  
C. J. Robinson ◽  
R. Palomares-García ◽  
J. Gómez-Gutierrez
Keyword(s):  
Vertical Distribution ◽  
Gulf Of California ◽  
Fish Larvae ◽  
Pelagic Fish ◽  
Small Pelagic Fish ◽  
Sardinops Sagax ◽  
Etrumeus Teres ◽  
Engraulis Mordax ◽  
The Vertical Distribution

Análisis de la distribucion vertical de la abundancia de larvas de peces pelágicos menores en el Golfo de California mediante videocámaras submarinas Se utilizaron dos tipos de videocámaras submarinas para estudiar la distribución y abundancia vertical de larvas de los peces pelágicos menores Engraulis mordax, Etrumeus teres y Sardinops sagax a 1 m de resolución, en una localidad en el norte del Golfo de California con condiciones de calma y alta densidad de sardinas adultas. La mayor abundancia promedio (900 larvas m -1 min -1 ) se encontró inmediatamente arriba de la termoclina (33 m) y la picnoclina (36 m), aparentemente no asociada al máximo de clorofila detectado en superficie, ni a la mayor densidad de peces adultos (10 -20 m). Las observaciones con video permitieron determinar la distribución vertical a una resolución imposible de obtener mediante muestreos con redes; sin embargo, esta es una técnica poco útil en zonas con elevada velocidad de las corrientes.

Interactions multispécifiques: répartition spatio-temporelle des larves de capelan (Mallotus villosus), d'éperlan (Osmerus mordax) et de hareng de l'Atlantique (Clupea harengus harengus) an sein de la communauté planctonique de l'estuaire moyen du Saint-Laurent

1982 ◽  
Vol 39 (8) ◽  
pp. 1164-1174 ◽  
Author(s):  
R. Courtois ◽  
M. Simoneau ◽  
J. J. Dodson
Keyword(s):  
Fish Larvae ◽  
Clupea Harengus ◽  
Temporal Organization ◽  
Physical Factors ◽  
Osmerus Mordax ◽  
Mallotus Villosus ◽  
Saint Lawrence River ◽  
Capelin Mallotus Villosus ◽  
Clupea Harengus Harengus ◽  
Species Specific

The study of the spatial and temporal organization of the planktonic community of the middle estuary of the Saint Lawrence River revealed that fish larvae were distributed in such a way as to minimize interactions between species. Smelt (Osmerus mordax) larvae were distributed upstream whereas capelin (Mallotus villosus) and Atlantic herring (Clupea harengus harengus) larvae were found downstream in June 1979. Capelin larvae were more abundant at the surface (0–20 m) whereas herring larvae were concentrated in deeper waters (20–60 m). The ecological separation observed was maintained by multiple physical factors and appeared to be the consequence of species-specific reproductive strategies. The abundance of chaetognaths, euphausiids, and amphipods in deeper waters suggests that these forms could be important predators of fish larvae. Herring larvae may be particularly vulnerable because of their distribution in deep water. Capelin larvae which are very abundant in June could also be vulnerable to predation during the diurnal migrations of the macroplankton. Smelt larvae appear to be little affected by predation from these forms as a result of their distribution in fresher waters.

Seasonal vertical distribution and diel migration of zooplankton in a temperate stratified lake

Biologia ◽  
2011 ◽  
Vol 66 (2) ◽  
Author(s):  
Evangelia Doulka ◽  
George Kehayias
Keyword(s):  
Vertical Distribution ◽  
Zooplankton Community ◽  
Abiotic Factor ◽  
High Concentration ◽  
Diel Migration ◽  
Four Seasons ◽  
Diel Vertical Migrations ◽  
Vertical Segregation ◽  
And Migration ◽  
The Vertical Distribution

AbstractThe investigation of the vertical distribution of the zooplankton community in the temperate Lake Trichonis during four seasons in 2005, showed the existence of vertical segregation among species, ontogenetic stages and sexes within and between the major groups. In each season, the two or three more abundant rotifer species distributed at separate depth layers, while this feature was maintained during the entire 24 h period, since no diel vertical migrations (DVM) were performed. In contrast, the crustacean community, comprised mainly by the calanoid copepod Eudiaptomus drieschi and the cladoceran Diaphanosoma orghidani, showed various patterns of DVM, being more pronounced in spring and summer. Females of E. drieschi distributed deeper than males, while the copepod nauplii were found mainly in the surface layer in all four seasons. Temperature was the most important abiotic factor affecting directly and indirectly the vertical distribution and migration of various species. During stratification, the metalimnion was the most productive layer in Lake Trichonis, having maximum values of dissolved oxygen and low transparency due to high concentration of organic matter and phytoplankton. The DVM patterns of the crustaceans indicate that the metalimnion acts probably as a daylight refuge against predation by Atherina boyeri, which is the dominant planktivorous fish in the lake.

Vertical Distribution of Northern Shrimp (Pandalus borealis) Larvae in the Gulf of St Lawrence; Implications for Trophic Interactions and Transport

1994 ◽  
Vol 51 (1) ◽  
pp. 123-132 ◽  
Author(s):  
Patrick Ouellet ◽  
Denis Lefaivre
Keyword(s):  
Vertical Distribution ◽  
Water Column ◽  
Suspended Particle ◽  
Stage I ◽  
Vertical Position ◽  
Pandalus Borealis ◽  
Northern Shrimp ◽  
Residual Transport ◽  
Larval Emergence ◽  
The Vertical Distribution

In the northwestern Gulf of St. Lawrence in spring 1987 and 1988, stage I and II northern shrimp (Pandalus borealis) larvae were concentrated in the upper (<30 m) layers above the permanent pycnocline and coincident with subsurface chlorophyll a and suspended particle concentration maxima; this was above other macrozooplankton taxa in the daytime. Shrimp larvae maintained their vertical position relative to the maximum density gradient in the water column in daytime but moved towards the surface at night. Estimation of larval residual transport (~66 km) during the first developmental stage (12 d) corresponded to the horizontal scale of patches of stage I shrimp larvae in the northwest sector of the Gulf. The result is consistent with the suggestion of localized and short-duration larval emergence in the sector. The direction of mass transport and current speed were similar throughout the upper layers of the water column; consequently, the direction and magnitude of larval shrimp transport were not dependent on their vertical position. We suggest that the vertical distribution maintained by shrimp larvae is a mechanism to ensure maximum food availability and to optimize development time in the stratified water of the northwestern Gulf of St. Lawrence.

scholarly journals Sinking microplastics in the water column: simulations in the Mediterranean Sea

Ocean Science ◽  
2021 ◽  
Vol 17 (2) ◽  
pp. 431-453
Author(s):  
Rebeca de la Fuente ◽  
Gábor Drótos ◽  
Emilio Hernández-García ◽  
Cristóbal López ◽  
Erik van Sebille
Keyword(s):  
Vertical Distribution ◽  
Mediterranean Sea ◽  
Water Column ◽  
Large Scale ◽  
Circulation Model ◽  
Small Scale ◽  
The Mediterranean ◽  
Scale Turbulence ◽  
Non Gaussian ◽  
The Vertical Distribution

Abstract. We study the vertical dispersion and distribution of negatively buoyant rigid microplastics within a realistic circulation model of the Mediterranean sea. We first propose an equation describing their idealized dynamics. In that framework, we evaluate the importance of some relevant physical effects (inertia, Coriolis force, small-scale turbulence and variable seawater density), and we bound the relative error of simplifying the dynamics to a constant sinking velocity added to a large-scale velocity field. We then calculate the amount and vertical distribution of microplastic particles on the water column of the open ocean if their release from the sea surface is continuous at rates compatible with observations in the Mediterranean. The vertical distribution is found to be almost uniform with depth for the majority of our parameter range. Transient distributions from flash releases reveal a non-Gaussian character of the dispersion and various diffusion laws, both normal and anomalous. The origin of these behaviors is explored in terms of horizontal and vertical flow organization.

Diel vertical distribution of fish larvae during the winter-mixing period in the Northwestern Mediterranean

2004 ◽  
Vol 61 (8) ◽  
pp. 1243-1252 ◽  
Author(s):  
A. Sabatés
Keyword(s):  
Vertical Distribution ◽  
Water Column ◽  
Fish Species ◽  
Fish Larvae ◽  
Distribution Patterns ◽  
Diel Variation ◽  
Surface Layers ◽  
Light Levels ◽  
Vertical Distributions ◽  
The Vertical Distribution

Abstract The vertical distributions of the larvae of shelf and oceanic fish species that spawn during the winter-mixing period in the Mediterranean are described from 22 vertically stratified plankton tows. Diel differences in the vertical distribution patterns in relation to physical data and potential prey abundance throughout the water column were examined. Even in absence of stratification, the larvae of the various fish species showed different patterns of vertical distribution and diel changes. The larvae of shelf-dwelling species were found in the surface layers, mainly above 50-m depth, and with some exceptions, with very little diel variation in depth distribution. Therefore, the vertical distribution of the larvae of these species coincided with the maximum concentrations of their potential food, nauplii and copepodite stages of copepods. The larvae of mesopelagic fishes showed deeper distributions in the water column and most of these species were located closer to the surface during the day than at night. Given the homogeneity of the physical characteristics throughout the water column, except for light, this behaviour may be determined not only by the higher concentration of prey in the surface layers but also by adequate light levels for feeding.

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