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.

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.

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.

scholarly journals Vertical Distribution of Particulates within the Near-Surface Layer of Dry Bulk Port and Influence Mechanism: A Case Study in China

2019 ◽  
Vol 11 (24) ◽  
pp. 7135 ◽  
Author(s):  
Jinxing Shen ◽  
Xuejun Feng ◽  
Kai Zhuang ◽  
Tong Lin ◽  
Yan Zhang ◽  
...  
Keyword(s):  
Vertical Distribution ◽  
Weather Conditions ◽  
Dust Suppression ◽  
Near Surface ◽  
Cargo Handling ◽  
Port Operation ◽  
Pm10 And Pm2.5 ◽  
The Impact ◽  
The Vertical Distribution ◽  
Porous Fence

Knowing the vertical distribution of ambient particulate matter (PM) will help port authorities choose the optimal dust-suppression measures to reduce PM concentrations. In this study, we used an unmanned aerial vehicle (UAV) to assess the vertical distribution (0–120 m altitude) of PM in a dry bulk port along the Yangtze River, China. Total suspended particulates (TSP), PM10, and PM2.5 concentrations at different altitudes were measured at seven sites representing different cargo-handling sites and a background site. Variations in results across sites make it not suitable to characterize the vertical distribution of PM concentration at this port using simple representative distributions. Bulk cargo particle size, fog cannon use, and porous fence all affected the vertical distribution of TSP concentrations but had only minor impacts on PM10 and PM2.5 concentrations. Optimizing porous fence layout according to weather conditions and cargo demand at port have the most potential for mitigating PM pollution related to port operation. As ground-based stations cannot fully measure vertical PM distributions, our methods and results represent an advance in assessing the impact of port activities on air quality and can be used to determine optimal dust-suppression measures for dry bulk ports.

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 DISTRIBUCIÓN Y DENSIDAD DE ICTIOPLANCTON EN EL ESTUARIO DE BAHÍA MÁLAGA, PACÍFICO COLOMBIANO (SEPTIEMBRE DE 2009-FEBRERO DE 2010)

2016 ◽  
Vol 43 (1) ◽  
Author(s):  
Diana Medina Contreras ◽  
Jaime Cantera ◽  
Eugenia Escarria ◽  
Luz M Mejía Ladino
Keyword(s):  
Fish Assemblages ◽  
Larval Fish ◽  
Fish Larvae ◽  
Larval Density ◽  
Temporal Distribution ◽  
Mesh Size ◽  
Temporal Variations ◽  
Taxonomic Composition ◽  
Total Density ◽  
The Relationship

The density, taxonomic composition, and spatial and temporal distribution of the estuarine ichthyoplankton of Bahía Málaga (Pacific coast of Colombia) are described, as well as the relationship between biological parameters and some physicochemical variables. Samples were collected at 12 stations along the principal navigation canal; these samples were taken in four areas following the design of Barletta-Bergan. Surface sweeps were carried out with a conical-cylindrical net (mesh size 500 µm, mouth diameter 0.6 m, length 3.5 m). Salinity and temperature were measured before each sweep. A total of 69019 larvae/1000 m³, representing 23 families, 36 genera and 40 species were collected during monthly sampling from September, 2009 to February, 2010. Carangidae (39.0%) was the most abundant family, followed by Sciaenidae (27.1%) and Engraulidae (20.1%). The most frequent families were Sciaenidae (26.6%), followed by Carangidae (22.8%) and Engraulidae (14.7%) which are important families in larval fish assemblages in tropical estuaries. Eighty percent of total density was provided by six species, of which Seriola morphotype 1 (Carangidae) and Cetengraulis mysticetus (Engraulidae) were the most abundant and dominant. No correlation was found between density and salinity (Spearman, R = 0.23) or temperature (Spearman, R = 0.51). Analysis of spatial and temporal variations of larval density shows significant differences among the months sampled (Anova, p = 0.0029; p < 0.05), but not among areas (Anova, p = 0.078), suggesting that Bahía Málaga offers adequate conditions for the presence of fish larvae.

scholarly journals Depth is Relative: The Importance of Depth on TEP in the Near Surface Environment

2019 ◽  
Author(s):  
Tiera-Brandy Robinson ◽  
Christian Stolle ◽  
Oliver Wurl
Keyword(s):  
Vertical Distribution ◽  
Spatial Scales ◽  
Small Scale ◽  
Surface Microlayer ◽  
Near Surface ◽  
Chl A ◽  
Sea Surface Microlayer ◽  
Carbon Transfer ◽  
The Vertical Distribution ◽  
Surface Environment

Abstract. Transparent exopolymer particles (TEP) are a major source for both organic matter (OM) and carbon transfer in the ocean and into the atmosphere. Consequently, understanding the vertical distribution of TEP and the processes which impact its movement are important in understanding the OM and carbon pools on a larger scale. Additionally, most studies looking at the vertical profile of TEP have focused on large depth scales from 5 to 1000s meters and have omitted the near surface environment. Results from a study of TEP enrichment in the sea surface microlayer (SML) in different regions (tropical, temperate) has shown that while there is a correlation between TEP abundance and primary production (PP) on larger or seasonal scales, such relationships break down on shorter time and spatial scales. Using a novel small-scale vertical sampler, the vertical distribution of TEP within the uppermost 2 meters was investigated. With a maximum variance of TEP abundance between depths (1.39 × 106 µg XG eq2 L-2) and a minimum variance of (6 × 102 µg XG eq2 L-2) the vertical distribution of TEP was found to be both heterogeneous and homogeneous at times. Results from the enrichment of TEP and Chl a between different regions has shown TEP enrichment to be greater in oligotrophic waters, when both Chl a and TEP abundance was low, suggesting the importance of abiotic sources for the enrichment of TEP in the SML. However, considering multiple additional parameters that were sampled, it is clear that no single parameter could be used as a proxy for TEP heterogeneity, other probable biochemical drivers of TEP transport are discussed.

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.

scholarly journals Interannual variation of larval fish assemblages in the Gulf of Cádiz (SW Iberian Peninsula) in relation to summer oceanographic conditions

2006 ◽  
Vol 49 (2) ◽  
pp. 287-296 ◽  
Author(s):  
Paulo Mafalda Júnior ◽  
Juan Perez de Rubín
Keyword(s):  
Fish Assemblages ◽  
Larval Fish ◽  
Fish Larvae ◽  
Water Discharge ◽  
Estuarine System ◽  
Interannual Variations ◽  
Gulf Of Cadiz ◽  
Engraulis Encrasicolus ◽  
Gulf Of Cádiz ◽  
Sardinella Aurita

Two ichthyoplankton surveys were conducted during July 1994 and July 1995 in the Gulf of Cádiz with the aim of describing composition, abundance, distribution patterns and interannual variations of larval fish assemblages. Interannual differences were found in this study. In 1994, higher salinities were observed at external sites, though in 1995, higher values were observed at intermediate sites. The upper water column was warmer in 1994 and had less fish larvae density. During 1994, Sardinella aurita and Engraulis encrasicolus were abundant but spatial location was opposite. In 1995, abundance of both species was very different, but with similar spatial pattern. Cluster analysis revealed well-defined groups of stations and assemblages of larvae, primarily related to bathymetry. The "inshore assemblage" occupied the shallow coast area; its characteristics species being closely related to the estuarine system, mainly comprising Engraulis encrasicolus and Gobiidae. The "shelf assemblage" occupied the continental shelf and its characteristics species consisted of larvae whose adults inhabited the shelf province and spawn in the same zone, like Sardinella aurita and Trachurus spp. Interannual variations in composition and extension of the subgroups could be attributed to the main circulation patterns, continental water discharge and spawning strategies of fishes.

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