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Kelly J. Benoit-bird - One of the best experts on this subject based on the ideXlab platform.
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Nocturnal light and lunar cycle effects on Diel Migration of micronekton
Limnology and Oceanography, 2009Co-Authors: Kelly J. Benoit-bird, Daniel W. WisdomaAbstract:The roles of nocturnal light and lunar phase in the Diel Migration of micronekton from a nearshore scattering layer were examined. Migration patterns were measured over six complete lunar cycles using moored upwardlooking echosounders while nocturnal surface irradiance was recorded. We hypothesized that animals would remain at a constant isolume at night despite changes in nocturnal illumination between nights. The scattering layer migrated closer to the surface during dark nights than during well-lit ones. However, this movement was not enough to compensate for observed changes in light, and at night animals often remained at light levels higher than they experience at depth during the day. Light and lunar cycle were not completely coupled, allowing separation of the light and lunar phases. Contrary to the initial hypothesis, lunar phase accounted for substantially more of the variability in layer Migration than surface irradiance, showing strong effects on the scattering layer’s depth and animal density within the layer. Changes in layer depth and animal density were amplified a small amount by variations in light level but were minimized by the seafloor in shallow areas. The horizontal component of the scattering layer’s Migration was also affected by lunar phase, with animals remaining further offshore in deeper waters during nights near and during the full moon, even when these were not the nights with the highest light levels. These results suggest that moonlight may be a cue for an endogenous lunar rhythm in the process of Diel Migration rather than a direct cause. Diel vertical Migration of zooplankton and nekton, active movement from deep, dark waters where animals reside during the day to near-surface waters at night (Longhurst 1976), is thought to be ultimately driven by maximization of survival controlled by food, predators, and physiological costs (Zaret and Suffern 1976; Enright 1977). However, individual animals have limited means to follow predator and prey distributions in the water column. Therefore, environmental cues must be used as proxies. Light is one of the strongest environmental cues available to migrating animals and is hypothesized to serve as a proxy for the risk of predation by visual predators (see a review in Forward 1988). Light is generally accepted as playing an important role in controlling the timing of Diel vertical Migration since most Migrations occur at sunrise and sunset (Esterley 1911; see a review in Ringelberg 1995). Two mechanisms to explain how light may trigger vertical Migration have been examined: absolute light intensity and rate of light change. One hypothesis about absolute light levels suggests that animals remain at an optimum light level, following this constant level, or isolume, up and down in the water column as the surface irradiance changes (Michael 1911; Longhurst 1976). Alternatively, animals may use an absolute threshold value of light to trigger upward movement when light becomes lower than the threshold (Esterley 1911; Pearre 1973). The absolute level of light may be difficult for animals to detect, however. Instead, animals may use the rate of the change in light intensity to cue Migration (reviewed in Ringelberg 1995).
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Diel variation of zooplankton distributions in Hawaiian waters favors horizontal Diel Migration by midwater micronekton
Marine Ecology Progress Series, 2008Co-Authors: Kelly J. Benoit-bird, Marnie Jo Zirbel, Margaret A. McmanusAbstract:Micronekton in deep-scattering layers around the Hawaiian Islands undergo Diel Migrations with both vertical and horizontal components. We sought to determine whether resource availability provides an adaptive explanation for this Migration. We simultaneously measured the spatio-temporal patterns of micronekton, using acoustics and imaging optics, and of their potential zooplankton prey, using net tows, acoustics, and optics. Zooplankton biomass, density, and total abundance were higher at night than prior to sunset at nearshore sites, whereas relatively little Diel variation was observed offshore. All measures of zooplankton availability were 5 to 6 times higher nearshore than offshore during nighttime hours when migrating micronekton species were nearshore. There was no significant nearshore-offshore gradient in zooplankton prior to sunset, leading to 2 possible explanations for the day-night patterns in zooplankton: benthic emergence and vertical Migration coupled with horizontal motion. Analysis of taxonomic patterns from net tows did not support the benthic emergence hypothesis. All 3 zooplankton assessment techniques supported the conclusion that zooplankton distribution could favor horizontal Migration by micronekton given the pressures for micronketon to be in deep water during daylight to avoid predators. Recently pub- lished work has shown that small animals (2 to 10 cm in length) in scattering layers comprised of micronekton travel distances of at least 11 km roundtrip each night, often against currents, to obtain these increased food resources. The length and likely cost of the journey provides some insight about the importance of the potential feeding gains.
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Effects of scattering layer composition, animal size, and numerical density on the frequency dependence of volume backscatter
The Journal of the Acoustical Society of America, 2006Co-Authors: Kelly J. Benoit-birdAbstract:The mesopelagic boundary community around the Hawaiian Islands is a land‐associated, sound scattering layer that undergoes Diel Migrations with both a vertical and horizontal component. A video camera system was developed to quantitatively examine the numerical density, size, and taxonomic composition of micronekton. The camera system was combined with a four‐frequency vessel‐mounted echosounder system (38, 70, 120, and 200 kHz) to document the full Migration range of micronekton and describe the changes in composition and density throughout their Diel Migration. Migrating animals split into multiple, distinct layers at night with differences in micronekton density, composition, and size. These differences were correlated with differences in the frequency response of volume backscatter. The relationship between these variables and backscatter intensity relationship between frequencies is complex. The results suggest strong partitioning of habitat by these animals in space and time, which, along with the h...
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Light and lunar cycle as cues to Diel Migration of a sound-scattering layer
The Journal of the Acoustical Society of America, 2004Co-Authors: Kelly J. Benoit-birdAbstract:The Hawaiian mesopelagic boundary community is an island‐associated midwater scattering layer comprised of small fishes, shrimps, and squids that undergoes Diel vertical as well as horizontal Migrations. It has been hypothesized that light levels are an important cue or trigger for vertical Migration and presumably, horizontal Migration. The Migration pattern of the scattering layer was measured over complete lunar cycles while the incident light levels were recorded. Due to differences in the rise and set times of the moon and cloud cover, light and lunar cycle were not completely coupled, allowing separation of the light effects of moon phase and other cues associated with lunar cycle. Four calibrated echosounder moorings were deployed with approximately even spacing, perpendicular to the leeward coast of Oahu. Moorings were deployed for one complete lunar cycle at each of three locations, recording 10 echoes every 15 min. Light sensors measured the nocturnal light intensity at 30‐s intervals. Statistic...
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Diel Migration dynamics of an island-associated sound-scattering layer
Deep Sea Research Part I: Oceanographic Research Papers, 2004Co-Authors: Kelly J. Benoit-birdAbstract:The Hawaiian mesopelagic boundary community, consisting ofisland-associated, midwater sound-scattering layers, undergoes Diel Migrations with both vertical and horizontal components. To understand the dynamics ofthe community’s Migration at fine temporal scales, we utilized a bottom-mounted, 200-kHz active-acoustic mooring that transmitted 10 signals every 15 min, from dusk until dawn for 5 days. Five moorings were deployed 1.0–3.0 km from the leeward coast ofOahu in 0.5 km intervals. Two layers within the boundary community were observed to undergo simultaneous Diel vertical and horizontal Migration. The shallow layer came within 10 m ofthe surface and 1 km ofthe shoreline. The deeper layer remained 90 m from the surface and 2.5 km of the shoreline. Vertical Migration rates were measured at 0–1.7 m min –1 while the horizontal rate averaged 1.7 km h –1 , swamping the vertical movement. The turning point ofthe Migration pattern was observed 45 min bef ore the midpoint between sunset and sunrise. Until the Migration’s turning point, scattering strength increased relatively constantly as the animals migrated towards shore, with the highest scattering densities found in the shallowest areas at midnight. Total scattering strength measured at the leading and trailing edge ofthe layer support the hypothesis that increased animal densities nearshore are related to packing as mesopelagic animals avoid the surface and the bottom. We observed high levels of biomass moving rapidly, over a great distance, into shallow waters very close to shore providing insight into the significant link the mesopelagic boundary community provides between nearshore and oceanic systems. r 2004 Elsevier Ltd. All rights reserved.
Francois J. Saucier - One of the best experts on this subject based on the ideXlab platform.
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Modeling the interactions between the seasonal and Diel Migration behaviors of Calanus finmarchicus and the circulation in the Gulf of St. Lawrence (Canada)
Journal of Marine Systems, 2011Co-Authors: Frederic Maps, Bruno Zakardjian, Stéphane Plourde, Francois J. SaucierAbstract:The Gulf of St.-Lawrence (GSL) is a dynamic region supporting a productive pelagic ecosystem. This environment presents unique opportunities to study the interactions between the population dynamics of planktonic species and the variability of physical processes. The copepod Calanus finmarchicus is a dominant component of zooplankton biomass and abundance in the GSL We developed a 3-D coupled physical-biological numerical model in order to study the population dynamics of C. finmarchicus in the GSL for the year 1999. We coupled a life cycle model of C. finmarchicus representing the average properties of the population in terms of egg production, development, Migration behavior and mortality to a regional circulation model driven by realistic atmospheric, hydrological and oceanic forcing. The distribution and abundance patterns of C. finmarchicus were sensitive to the Migration behavior owing to the strong vertical and horizontal shears in the circulation. Both the timing of seasonal ontogenetic vertical Migrations and the Diel vertical Migrations appeared to be essential to produce simulation results similar to the observations and to ensure the perennial presence of a local population in the GSL. (C) 2011 Elsevier B.V. All rights reserved.
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Modeling the interactions between the seasonal and Diel Migration behaviors of Calanus finmarchicus and the circulation in the Gulf of St. Lawrence (Canada)
Journal of Marine Systems, 2011Co-Authors: Frederic Maps, Bruno Zakardjian, Stéphane Plourde, Francois J. SaucierAbstract:The Gulf of St.-Lawrence (GSL) is a dynamic region supporting a productive pelagic ecosystem. This environment presents unique opportunities to study the interactions between the population dynamics of planktonic species and the variability of physical processes. The copepod Calanus finmarchicus is a dominant component of zooplankton biomass and abundance in the GSL. We developed a 3-D coupled physical–biological numerical model in order to study the population dynamics of C. finmarchicus in the GSL for the year 1999. We coupled a life cycle model of C. finmarchicus representing the average properties of the population in terms of egg production, development, Migration behavior and mortality to a regional circulation model driven by realistic atmospheric, hydrological and oceanic forcing. The distribution and abundance patterns of C. finmarchicus were sensitive to the Migration behavior owing to the strong vertical and horizontal shears in the circulation. Both the timing of seasonal ontogenetic vertical Migrations and the Diel vertical Migrations appeared to be essential to produce simulation results similar to the observations and to ensure the perennial presence of a local population in the GSL.
Bruno Zakardjian - One of the best experts on this subject based on the ideXlab platform.
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Modeling the interactions between the seasonal and Diel Migration behaviors of Calanus finmarchicus and the circulation in the Gulf of St. Lawrence (Canada)
Journal of Marine Systems, 2011Co-Authors: Frederic Maps, Bruno Zakardjian, Stéphane Plourde, Francois J. SaucierAbstract:The Gulf of St.-Lawrence (GSL) is a dynamic region supporting a productive pelagic ecosystem. This environment presents unique opportunities to study the interactions between the population dynamics of planktonic species and the variability of physical processes. The copepod Calanus finmarchicus is a dominant component of zooplankton biomass and abundance in the GSL. We developed a 3-D coupled physical–biological numerical model in order to study the population dynamics of C. finmarchicus in the GSL for the year 1999. We coupled a life cycle model of C. finmarchicus representing the average properties of the population in terms of egg production, development, Migration behavior and mortality to a regional circulation model driven by realistic atmospheric, hydrological and oceanic forcing. The distribution and abundance patterns of C. finmarchicus were sensitive to the Migration behavior owing to the strong vertical and horizontal shears in the circulation. Both the timing of seasonal ontogenetic vertical Migrations and the Diel vertical Migrations appeared to be essential to produce simulation results similar to the observations and to ensure the perennial presence of a local population in the GSL.
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Modeling the interactions between the seasonal and Diel Migration behaviors of Calanus finmarchicus and the circulation in the Gulf of St. Lawrence (Canada)
Journal of Marine Systems, 2011Co-Authors: Frederic Maps, Bruno Zakardjian, Stéphane Plourde, Francois J. SaucierAbstract:The Gulf of St.-Lawrence (GSL) is a dynamic region supporting a productive pelagic ecosystem. This environment presents unique opportunities to study the interactions between the population dynamics of planktonic species and the variability of physical processes. The copepod Calanus finmarchicus is a dominant component of zooplankton biomass and abundance in the GSL We developed a 3-D coupled physical-biological numerical model in order to study the population dynamics of C. finmarchicus in the GSL for the year 1999. We coupled a life cycle model of C. finmarchicus representing the average properties of the population in terms of egg production, development, Migration behavior and mortality to a regional circulation model driven by realistic atmospheric, hydrological and oceanic forcing. The distribution and abundance patterns of C. finmarchicus were sensitive to the Migration behavior owing to the strong vertical and horizontal shears in the circulation. Both the timing of seasonal ontogenetic vertical Migrations and the Diel vertical Migrations appeared to be essential to produce simulation results similar to the observations and to ensure the perennial presence of a local population in the GSL. (C) 2011 Elsevier B.V. All rights reserved.
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A biophysical model of the interaction between vertical Migration of crustacean zooplankton and circulation in the Lower St. Lawrence Estuary
Canadian Journal of Fisheries and Aquatic Sciences, 1999Co-Authors: Bruno Zakardjian, Jeffrey A. Runge, Stéphane Plourde, Yves GrattonAbstract:As an essential step in modeling the influence of circulation on the population dynamics of marine planktonic copepods, we define a simple formulation of swimming behavior that can be used in both Eulerian and Lagrangian models. This formulation forces aggregation of the population toward a preferential depth and can be stage specific and time varying, thus allowing description of either diurnal or seasonal vertical Migration. We use the formulation to examine the interaction between the circulation and vertical distribution in controlling horizontal distribution of the common planktonic copepod Calanus finmarchicus in the Lower St. Lawrence Estuary, Canada. We first introduce Diel Migration into a simple one-dimensional model and then into a model of residual two-dimensional circulation patterns representative of conditions encountered in the Lower St. Lawrence Estuary. Results from the latter indicate that interactions between circulation and stage-specific swimming behaviors are the main mechanisms for...
J. L. Manuel - One of the best experts on this subject based on the ideXlab platform.
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Vertical Migration for horizontal transport while avoiding predators: II. Evidence for the tidal/Diel model from two populations of scallop (Placopecten magellanicus) veligers
Journal of Plankton Research, 1997Co-Authors: J. L. Manuel, Christopher M PearceAbstract:We examined the vertical Migration behavior of scallop (Placopecten magellanicus) veligers in mesocosms and in previously reported field studies. Evidence suggests that these bivalve veligers migTate in response to both tidal and diurnal stimuli in a manner similar to a proposed tidal/Diel model. Both populations have a diurnal response to solar cues. The response to tidal cues differs between the Georges Bank and Passamaquoddy Bay populations. Georges Bank veligers appear to utilize the differences in tidal phase that occur with depth to transport them in a northeasterly direction, thus maintaining the population on the bank. Passamaquoddy Bay veligers respond by swimming up at slack water (high and low tides) and down when currents are strongest. Such behavior would minimize dispersal on the strong tidal currents in the Bay of Fundy and thus also tend to maintain a population within an area. Horizontal transport resulting from vertical Migration is the most likely selective pressure to CTeate and maintain these different behaviors against the homogenizing effects of Migration between the two populations. The implications of inherited differences in behavior probably require consideration in the management of both wild and cultured populations. Common sampling practices that obscure the tidal part of tidal/Diel Migration, including averaging the results from several days of sampling, sampling too infrequently to perceive a tidal periodicity, and assuming that only behavior that changes at high and low tides will affect horizontal transport, need to be avoided in studies of vertical Migration.
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Vertical Migration for horizontal transport while avoiding predators: I. A tidal/Diel model
Journal of Plankton Research, 1997Co-Authors: J. L. Manuel, Ronald K. O’dorAbstract:Research into the vertical Migration behavior of scallop (Placopecten magellanicus) veligers has led us to examine whether these, and possibly other small zooplankters, may migrate in response to a combination of tidal and Diel stimuli. This paper uses Hill's (1991) model to evaluate the horizontal transport effects of such Migrations. We demonstrate that most types of vertical Migration behavior reported in the literature (e.g. nocturnal, twilight, midnight sink) appear at differ- ent phases of the lunar cycle. Moreover, migrating in response to both of these cues may provide hori- zontal transport advantages if the zooplankter is very small (unable to migrate the full water column depth) and/or has difficulty determining its position in the water column (especially if the behavior also holds it in regions of increased shear). Such behavior need not interfere with other advantages of vertical Migration, including avoiding predation, avoiding UV light, searching for patchy food, etc. Tidal/Diel Migration may have distinct advantages for occupying new habitats or coping with local changes associated with altered current regimes. Because averaging the results of several days, sam- pling less frequently than every 2 h or sequential sampling of different sites is likely to obscure the tidal portion of a tidal/Diel Migration, such behavior could be common without being obvious to researchers. Aliasing of the lunar and solar cycles (a 14.8 day period) may allow the detection of tidal period Migrations in long-term records with lower sampling frequencies.
Stéphane Plourde - One of the best experts on this subject based on the ideXlab platform.
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Modeling the interactions between the seasonal and Diel Migration behaviors of Calanus finmarchicus and the circulation in the Gulf of St. Lawrence (Canada)
Journal of Marine Systems, 2011Co-Authors: Frederic Maps, Bruno Zakardjian, Stéphane Plourde, Francois J. SaucierAbstract:The Gulf of St.-Lawrence (GSL) is a dynamic region supporting a productive pelagic ecosystem. This environment presents unique opportunities to study the interactions between the population dynamics of planktonic species and the variability of physical processes. The copepod Calanus finmarchicus is a dominant component of zooplankton biomass and abundance in the GSL. We developed a 3-D coupled physical–biological numerical model in order to study the population dynamics of C. finmarchicus in the GSL for the year 1999. We coupled a life cycle model of C. finmarchicus representing the average properties of the population in terms of egg production, development, Migration behavior and mortality to a regional circulation model driven by realistic atmospheric, hydrological and oceanic forcing. The distribution and abundance patterns of C. finmarchicus were sensitive to the Migration behavior owing to the strong vertical and horizontal shears in the circulation. Both the timing of seasonal ontogenetic vertical Migrations and the Diel vertical Migrations appeared to be essential to produce simulation results similar to the observations and to ensure the perennial presence of a local population in the GSL.
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Modeling the interactions between the seasonal and Diel Migration behaviors of Calanus finmarchicus and the circulation in the Gulf of St. Lawrence (Canada)
Journal of Marine Systems, 2011Co-Authors: Frederic Maps, Bruno Zakardjian, Stéphane Plourde, Francois J. SaucierAbstract:The Gulf of St.-Lawrence (GSL) is a dynamic region supporting a productive pelagic ecosystem. This environment presents unique opportunities to study the interactions between the population dynamics of planktonic species and the variability of physical processes. The copepod Calanus finmarchicus is a dominant component of zooplankton biomass and abundance in the GSL We developed a 3-D coupled physical-biological numerical model in order to study the population dynamics of C. finmarchicus in the GSL for the year 1999. We coupled a life cycle model of C. finmarchicus representing the average properties of the population in terms of egg production, development, Migration behavior and mortality to a regional circulation model driven by realistic atmospheric, hydrological and oceanic forcing. The distribution and abundance patterns of C. finmarchicus were sensitive to the Migration behavior owing to the strong vertical and horizontal shears in the circulation. Both the timing of seasonal ontogenetic vertical Migrations and the Diel vertical Migrations appeared to be essential to produce simulation results similar to the observations and to ensure the perennial presence of a local population in the GSL. (C) 2011 Elsevier B.V. All rights reserved.
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A biophysical model of the interaction between vertical Migration of crustacean zooplankton and circulation in the Lower St. Lawrence Estuary
Canadian Journal of Fisheries and Aquatic Sciences, 1999Co-Authors: Bruno Zakardjian, Jeffrey A. Runge, Stéphane Plourde, Yves GrattonAbstract:As an essential step in modeling the influence of circulation on the population dynamics of marine planktonic copepods, we define a simple formulation of swimming behavior that can be used in both Eulerian and Lagrangian models. This formulation forces aggregation of the population toward a preferential depth and can be stage specific and time varying, thus allowing description of either diurnal or seasonal vertical Migration. We use the formulation to examine the interaction between the circulation and vertical distribution in controlling horizontal distribution of the common planktonic copepod Calanus finmarchicus in the Lower St. Lawrence Estuary, Canada. We first introduce Diel Migration into a simple one-dimensional model and then into a model of residual two-dimensional circulation patterns representative of conditions encountered in the Lower St. Lawrence Estuary. Results from the latter indicate that interactions between circulation and stage-specific swimming behaviors are the main mechanisms for...