Relationships among vertically structured in situ
 measures of turbulence, larval fish abundance and feeding success and copepods on Western Bank, Scotian Shelf

Many streams and large rivers present higher ichthyoplankton densities at night. However, in some rivers this does not occur and larvae are equally abundant during the day. Larval drift diel variation is an important information for planning sampling programs for evaluating larval distribution and production. The aim of this study was to test whether the abundance of larval fish was different at either period. We tested it by comparing day and night densities of characiform, clupeiform and siluriform larvae during five years in the Amazon and one year in Rio Negro. We found that larvae of three species of characiform and larvae of siluriform were equally abundant during day and night in the Amazon. Conversely, the catch of Pellona spp. larvae was significantly higher during the day. In Rio Negro, however, larval abundance was higher during the night. These results imply that day samplings estimate adequately the abundance of these characiform and siluriform larvae in the Amazon, but not Pellona larvae. Evaluations of larved densities of Rio Negro will have to consider night sampling.

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Larval fish diversity on the Scotian Shelf

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f00-111 ◽

2000 ◽

Vol 57 (9) ◽

pp. 1747-1760 ◽

Cited By ~ 12

Author(s):

N L Shackell ◽

K T Frank

Keyword(s):

Larval Fish ◽

Diversity Indices ◽

Fish Diversity ◽

Calanoid Copepods ◽

Scotian Shelf ◽

Genus Richness ◽

Using Data ◽

Negative Exponential ◽

Number Of Individuals ◽

The Relationship

We examined larval fish diversity on the Scotian Shelf using data, representing 91 genera, collected during the Scotian Shelf Ichthyoplankton Program from 1978 to 1982. Two diversity indices (genus richness (GR) and Shannon's entropy (H)) were relatively lower from December to February-March and relatively higher and stable from April to September-October. Taxon composition changed seasonally. Total median log abundance (log10(number of individuals + 1)·1000 m-3) was low from December to February, increased in March, was stable from April to June, and declined from July to October. Our results suggest that the abundance trends of most taxa were not coincident with either a spring or fall bloom of calanoid copepods. Log GR was significantly positively related to H (r = 0.62, p < 0.001, n = 1853). A negative exponential best described the relationship between log GR and log abundance (R2 = 0.77; log GR = 1.37(1 e-(1.13)(log abundance)), p < 0.001, n = 2357). Shannon's H was not related to log abundance in winter or in summer-fall and was negatively correlated in spring-summer (r = -0.12, p = 0.003, n = 593). Thus, diversity increases with abundance but the composition is dominated by relatively fewer genera at higher levels of abundance. Western - Sable Island banks had higher levels of GR and abundance in all seasons. Additional banks were diverse and productive during warmer months.

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Towards a balanced presentation and objective interpretation of acoustic and trawl survey data, with specific reference to the eastern Scotian Shelf

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/cjfas-2016-0113 ◽

2016 ◽

Vol 73 (12) ◽

pp. 1914-1921 ◽

Cited By ~ 4

Author(s):

J. Michael Jech ◽

Ian H. McQuinn

Keyword(s):

Atlantic Cod ◽

Management Strategies ◽

Pelagic Fish ◽

Trophic Levels ◽

Fish Abundance ◽

Forage Fish ◽

Specific Reference ◽

Trawl Survey ◽

Scotian Shelf ◽

Eastern Canada

A debate has developed over the ecosystem consequences following the collapse of Atlantic cod throughout the coastal waters of eastern Canada. The explosive increase in pelagic fish abundance in scientific bottom-trawl catches on the eastern Scotian Shelf has been interpreted as being due to either (i) a “pelagic outburst” of forage fish abundance resulting from predator release or conversely (ii) a change in pelagic fish vertical distribution leading to a “suprabenthic habitat occupation” thereby increasing their availability to bottom trawls. These two interpretations have diametrically opposing ecological consequences and suggest different management strategies for these important forage fish species. We argue that an objective evaluation of the available evidence supports the hypothesis that the abundance of forage fish has not increased in response to the demise of cod and other top predators, and the reliance on a single sampling gear with low catchability has biased and will continue to bias the interpretation of demographic trends of pelagic fish populations. We advocate that multiple sampling technologies providing alternative perspectives are needed for the monitoring and management of the various trophic levels if we are to achieve a balanced and objective understanding of marine ecosystems.

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Tidal and diurnal variations in larval fish abundance in an estuarine inlet in Ariake Bay, Japan: implication for selective tidal stream transport

Ecological Research ◽

10.1007/s11284-006-0001-4 ◽

2006 ◽

Vol 22 (1) ◽

pp. 165-171 ◽

Cited By ~ 19

Author(s):

Md. Shahidul Islam ◽

Manabu Hibino ◽

Masaru Tanaka

Keyword(s):

Larval Fish ◽

Diurnal Variations ◽

Fish Abundance ◽

Ariake Bay ◽

Tidal Stream ◽

Selective Tidal Stream Transport ◽

Stream Transport

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Assessing the performance of a multi-nested ocean circulation model using satellite remote sensing and in situ observations

Satellite Oceanography and Meteorology ◽

10.18063/som.2016.01.004 ◽

2016 ◽

Vol 1 (1) ◽

Cited By ~ 5

Author(s):

Shiliang Shan ◽

Jinyu Sheng ◽

Kyoko Ohashi ◽

Mathieu Dever

Keyword(s):

Remote Sensing ◽

Nova Scotia ◽

Ocean Circulation ◽

Satellite Remote Sensing ◽

Coastal Upwelling ◽

Circulation Model ◽

Tidal Mixing ◽

Scotian Shelf ◽

Ocean Circulation Model

This study presents a multi-nested ocean circulation model developed recently for the central Scotian Shelf. The model consists of four submodels downscaling from the eastern Canadian Shelf to the central Scotian Shelf. The model is driven by tides, river discharges, and atmospheric forcing. The model results are validated against observations, including satellite remote sensing data from GHRSST and Aquarius and in situ measurements taken by tide gauges, a marine buoy, ADCPs and CTDs. The ocean circulation model is able to capture variations of sea level, hydrography and the Nova Scotia Current on timescales of days to seasons over the central Scotian Shelf. Model results are used in a process study to examine the effect of tidal mixing and wind-driven coastal upwelling in the formation of cold surface waters along the coast of Nova Scotia.

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Hydrodynamic regime determines the feeding success of larval fish through the modulation of strike kinematics

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2017.0235 ◽

2017 ◽

Vol 284 (1853) ◽

pp. 20170235 ◽

Cited By ~ 16

Author(s):

Victor China ◽

Liraz Levy ◽

Alex Liberzon ◽

Tal Elmaliach ◽

Roi Holzman

Keyword(s):

High Speed ◽

Sparus Aurata ◽

Larval Fish ◽

Reynolds Numbers ◽

Early Ontogeny ◽

Hydrodynamic Regime ◽

Physical Growth ◽

Larval Feeding ◽

Feeding Success ◽

Order Of Magnitude

Larval fishes experience extreme mortality rates, with 99% of a cohort perishing within days after starting to actively feed. While recent evidence suggests that hydrodynamic factors contribute to constraining larval feeding during early ontogeny, feeding is a complex process that involves numerous interacting behavioural and biomechanical components. How these components change throughout ontogeny and how they contribute to feeding remain unclear. Using 339 observations of larval feeding attempts, we quantified the effects of morphological and behavioural traits on feeding success of Sparus aurata larvae during early ontogeny. Feeding success was determined using high-speed videography, under both natural and increased water viscosity treatments. Successful strikes were characterized by Reynolds numbers that were an order of magnitude higher than those of failed strikes. The pattern of increasing strike success with increasing age was driven by the ontogeny of traits that facilitate the transition to higher Reynolds numbers. Hence, the physical growth of a larva plays an important role in its transition to a hydrodynamic regime of higher Reynolds numbers, in which suction feeding is more effective.

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