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Adrian Flynn - One of the best experts on this subject based on the ideXlab platform.
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Micronekton assemblages and bioregional setting of the Great Australian Bight: A temperate northern boundary current system
Deep-sea Research Part Ii-topical Studies in Oceanography, 2018Co-Authors: Adrian Flynn, Rudy J. Kloser, C. SuttonAbstract:Abstract A multi-disciplinary pelagic ecosystem study of the Great Australian Bight (GAB) examined the micronekton communities and bioregionalisation in this area that harbours significant predator populations. Micronekton community structure and biomass differed between the eastern and central regions of the GAB. Regional differences were mainly driven by relatively high abundance of krill (Nematoscelis megalops, Nyctiphanes australis and Euphausia similis) in east GAB and high abundance of Maurolicus australis and chaetognaths in central GAB. Central GAB was also characterised by relatively high abundance of gelatinous zooplankton and small-bodied cephalopods. Lanternfishes were used as a model pelagic group to investigate the bioregional setting of the GAB. The analyses indicated that the oceanic habitats of the GAB had bioregional affinities with the subtropical Indian Ocean. However, over the continental slope, the east GAB had bioregional affinities with the Subtropical Convergence and grouped with western and southern Tasmania and the southern Tasman Sea. Lanternfish assemblage groups were compared against existing regionalisations that are based on physicochemical variables and the Delphi Method. No single existing scheme suitably reflected Lanternfish assemblage distributions, but parsimonious boundaries from existing schema were identified. This study demonstrates that the central GAB, where oil-and-gas exploration occurs alongside Marine Protected Area management, needs to be considered as a separate bioregion to the east GAB for the purposes of identifying conservation values and monitoring requirements.
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Lanternfish (Myctophidae) zoogeography off eastern Australia: a comparison with physicochemical biogeography.
PloS one, 2013Co-Authors: Adrian Flynn, N. Justin MarshallAbstract:In this first attempt to model the distributions of a mesopelagic fish family at this scale in the eastern Australian region (10°S to 57°S), Lanternfish species occurrence data spanning a period from 1928 to 2010 were modelled against environmental covariates. This involved: (1) data collation and taxonomic quality checking, (2) classification of trawls into “horizontal” (presence-absence) and “oblique” (presence-only) types, and classification of vertical migration patterns using existing literature and the species occurrence database, (3) binomial GAMs using presence-absence data for representative temperate, subtropical and tropical species to examine depth interactions with environmental covariates and refine the selection of environmental layers for presence-only MAXENT models, (4) Presence-only MAXENT modelling using data from all trawls and the reduced environmental layers, and (5) Multivariate analysis (area-wise and species-wise) of the resulting matrix of logistic score by geographic pixel. We test the hypothesis that major fronts in the region (Tasman Front, Subtropical Convergence, Subantarctic Front) represent zoogeographic boundaries. A four-region zoogeographic scheme is hypothesised: Coral Sea region, Subtropical Lower Water region, Subtropical Convergence/South Tasman region and Subantarctic region. The Tasman Front, Subtropical Convergence and Subantarctic Front represented zoogeographic boundaries. An additional boundary at ~25°S (coined the ‘Capricorn’ boundary) was adopted to delineate the Coral Sea from Subtropical Lower Water regions. Lanternfish zoogeographic regions are congruent with some aspects of two prevailing physicochemical biogeographic schema in the region, but neither of these schema alone accurately predicts Lanternfish distributions. As Lanternfishes integrate vertical ocean processes, the hypothesised Lanternfish zoogeography may represent a useful model for a generalised pelagic biogeography that should be tested for other oceanic groups.
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Lanternfish pisces myctophidae biomass distribution and oceanographic topographic associations at macquarie island southern ocean
Marine and Freshwater Research, 2012Co-Authors: Adrian Flynn, Alan WilliamsAbstract:Lanternfishes, which are important prey for demersal and diving predators at Macquarie Island in the Southern Ocean, have spatial patterns of distribution over the Macquarie Ridge that suggest biomass is enhanced where the Subantarctic Front (SAF) interacts with a break in the topography of the Ridge (the ‘Ridge Gap’). The summertime Lanternfish assemblage, documented here for the first time, comprised 23 taxa, dominated by Krefftichthys anderssoni and Gymnoscopelus braueri. Mean Lanternfish biomass was highest (3.13 g 1000 m–3) in the Ridge Gap habitat. Lowest mean biomass (0.71 g 1000 m–3) was recorded up-current of the SAF over the Abyssal Plain and intermediate biomass (1.26 g 1000 m–3) was recorded over the Macquarie Ridge. At Ridge Gap, a high abundance of K. anderssoni was recorded in the shallowest stratum (0–250 m) during the day. We hypothesised that the oceanographic–topographic interaction between the SAF and Ridge Gap creates eddy systems and productivity fronts that passively entrain and/or actively attract Lanternfishes to the Ridge Gap area. This oceanographic–topographic interaction depends on the spatial stability of the SAF in relation to the Macquarie Ridge and Ridge Gap and is vulnerable to climate-mediated change that may have flow-on effects to predators with commercial and conservation significance.
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spawning aggregation of the Lanternfish diaphus danae family myctophidae in the north western coral sea and associations with tuna aggregations
Marine and Freshwater Research, 2012Co-Authors: Adrian Flynn, John R PaxtonAbstract:A spawning aggregation of the Lanternfish Diaphus danae in the Coral Sea, that is fed on by spawning aggregations of yellowfin and bigeye tuna, has been sampled by mid-water trawling for the first time. Males and females in the aggregation occurred at a ratio of 23 to 1 and occupied two non-overlapping size classes (males 71.2–95.1-mm standard length (SL), females 99.0–121.4-mm SL). Hydrated oocytes with single oil droplets, which indicated imminent spawning, were in higher proportion in the first trawl (2134 hours to 2234 hours) than in the final trawl (0324 hours to 0424 hours) through the aggregation. Maximum estimated female D. danae fecundity (25 803) and gonadosomatic index (34.01) were higher than for any other Lanternfish species recorded. Bigeye tuna (Thunnus obesus) individuals collected from aggregations were estimated to have 81–319 D. danae specimens in their stomachs. The annual Coral Sea D. danae aggregation is the only confirmed Lanternfish spawning aggregation in Australian waters. The D. danae spawning aggregation provides a rich, transient foraging resource for spawning bigeye and yellowfin tuna in the Coral Sea, these being the only known tuna spawning aggregations in the Eastern Tuna and Billfish Fishery.
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Map of sample collection locations.
2012Co-Authors: Anela C. Choy, Adrian Flynn, Peter C. Davison, Jeffrey C. Drazen, Elizabeth J. Gier, Joel C. Hoffman, Jennifer P. Mcclain-counts, Todd W. Miller, Brian N. Popp, Steve W. RossAbstract:Approximate capture locations for species of Lanternfish (closed symbols) and dragonfish (open symbols) specimens analyzed in this study, from five distinct and globally distributed regions (Tasman Sea (TAS), California Current (CA), Gulf of Mexico (GOM), Hawaii (HI), and the Mid-Atlantic Ridge (MAR)).
Ichiro Aoki - One of the best experts on this subject based on the ideXlab platform.
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Target strength of the Lanternfish, Stenobrachius leucopsarus (family Myctophidae), a fish without an airbladder, measured in the Bering Sea
ICES Journal of Marine Science, 2006Co-Authors: Hiroki Yasuma, Yoshimi Takao, Kouichi Sawada, Kazushi Miyashita, Ichiro AokiAbstract:Yasuma, H., Takao, Y., Sawada, K., Miyashita, K., and Aoki, I. 2006. Target strength of the Lanternfish, Stenobrachius leucopsarus (family Myctophidae), a fish without an airbladder, measured in the Bering Sea. e ICES Journal of Marine Science, 63: 683e692. This paper reports theoretical values of target strength (TS) for the Lanternfish Stenobrachius leucopsarus, a fish without an airbladder, which dominates the Subarctic marine mesopelagic fish community. Two models for liquid-like slender bodies, the general prolate-spheroid model (PSM) and the deformed-cylinder model (DCM), were used to compute the TS of the fish relative to its orientation. The relative mass density g and the sound speed h in seawater were measured and used in both models. To confirm the appropriateness of the models, tethered experimental measurements were carried out at 38 kHz for five specimens. The value of g measured by the density-bottle method was very low (1.002e1.009) compared with that of marine fish in general. The value of h measured by the time-average approach was 1.032e1.039 at the water temperature at which S. leucopsarus is found. TS-fluctuation patterns against fish orientation (the TS pattern) estimated from the DCM and PSM were in good agreement in the area of their main lobes. Both models reproduced the main lobes of the measured TS patterns in near-horizontal orientation (
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target strength of the Lanternfish stenobrachius leucopsarus family myctophidae a fish without an airbladder measured in the bering sea
Ices Journal of Marine Science, 2006Co-Authors: Hiroki Yasuma, Yoshimi Takao, Kouichi Sawada, Kazushi Miyashita, Ichiro AokiAbstract:Yasuma, H., Takao, Y., Sawada, K., Miyashita, K., and Aoki, I. 2006. Target strength of the Lanternfish, Stenobrachius leucopsarus (family Myctophidae), a fish without an airbladder, measured in the Bering Sea. e ICES Journal of Marine Science, 63: 683e692. This paper reports theoretical values of target strength (TS) for the Lanternfish Stenobrachius leucopsarus, a fish without an airbladder, which dominates the Subarctic marine mesopelagic fish community. Two models for liquid-like slender bodies, the general prolate-spheroid model (PSM) and the deformed-cylinder model (DCM), were used to compute the TS of the fish relative to its orientation. The relative mass density g and the sound speed h in seawater were measured and used in both models. To confirm the appropriateness of the models, tethered experimental measurements were carried out at 38 kHz for five specimens. The value of g measured by the density-bottle method was very low (1.002e1.009) compared with that of marine fish in general. The value of h measured by the time-average approach was 1.032e1.039 at the water temperature at which S. leucopsarus is found. TS-fluctuation patterns against fish orientation (the TS pattern) estimated from the DCM and PSM were in good agreement in the area of their main lobes. Both models reproduced the main lobes of the measured TS patterns in near-horizontal orientation (<� 20(), and they were considered to be effective in measuring the TS of S. leucopsarus in a horizontal (swimming) position. After these comparative experiments, we computed the TS of 57 fish (27.8e106.9 mm) at 38, 70, 120, and 200 kHz, using the DCM. A plot of body length (in log scale) against TS showed a non-linear relationship at all frequencies. S. leucopsarus had a very low TS (<� 85 dB, TScm), suggesting that acoustic assessment would be highly sensitive, especially when the proportion of small fish is high (e.g. L/l < 2), and an appropriate frequency should be considered that takes into account both the length composition and the depth of occurrence.
Stein Kaartvedt - One of the best experts on this subject based on the ideXlab platform.
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ORIGINAL PAPER Seasonal variations in vertical migration of glacier Lanternfish,
2016Co-Authors: Benthosema Glaciale, Eivind Dypvik, Anders Rostad, Stein KaartvedtAbstract:Abstract The seasonal variations in glacier Lanternfish (Benthosema glaciale) vertical distribution and diel vertical migration (DVM) were studied by use of a bottom-moun-ted upward-facing 38 kHz echo sounder deployed at 392 m depth and cabled to shore in Masfjorden (*60520N, *5240E), Norway. Acoustic data from July 2007–October 2008 were analyzed, and scattering layers below *220 m during daytime were attributed to glacier Lanternfish based on net sampling in this, and previous studies, as well as from analysis of the acoustic data. At these depths, three different diel behavioral strategies were apparent: normal diel vertical migration (NDVM), inverse DVM (IDVM), and no DVM (NoDVM). NoDVM was present all year, while IDVM was present in autumn and winter, and NDVM was present during spring and summer. The sea-sonal differences in DVM behavior seem to correlate with previously established seasonal distribution of prey. We hypothesize that in regions with seasonally migrating zooplankton, such as where calanoid copepods overwinter at depth, similar plasticity in DVM behavior might occur in other populations of Lanternfishes
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ORIGINAL PAPER Inverse vertical migration and feeding in glacier Lanternfish (Benthosema glaciale)
2016Co-Authors: Eivind Dypvik, Thor A Klevjer, Stein KaartvedtAbstract:sounder was deployed at *400 m and cabled to shore in Masfjorden (*60520N, *5240E), Norway. The scattering layers seen during autumn (September–October) 2008 were identified by trawling. Glacier Lanternfish (Benthosema glaciale) were mainly distributed below *200 m and displayed three different diel behavioral strategies: normal diel vertical migration (NDVM), inverse DVM (IDVM) and no DVM (NoDVM). The IDVM group was the focus of this study. It consisted of 2-year and older individuals migrating to *200–270 m during the daytime, while descending back to deeper than *270 m during the night. Stomach content analysis revealed increased feeding dur-ing the daytime on overwintering Calanus sp. We conclude that visually searching glacier Lanternfish performing IDVM benefit from the faint daytime light in mid-waters when preying on overwintering Calanus sp
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vertical migration and diel feeding periodicity of the skinnycheek Lanternfish benthosema pterotum in the red sea
Deep Sea Research Part I: Oceanographic Research Papers, 2013Co-Authors: Eivind Dypvik, Stein KaartvedtAbstract:The vertical migration and diel feeding periodicity of the skinnycheek Lanternfish (Benthosema pterotum) were studied by use of a hull-mounted 38 kHz echo sounder, ROV-deployments and net-sampling at two locations (� 24148 0N, � 361150E and � 211270N, � 38150E) in the central Red Sea. The mesopelagic zone of the Red Sea represents an unusual environment with very high temperatures ( � 22 1C) and low zooplankton concentrations (o 10 individuals m � 3 below 600 m). The skinnycheek Lanternfish performed normal diel vertical migration from � 500 to 750 m during daytime to the epipelagic zone (upper � 200 m) at night. A strict feeding periodicity occurred; with the skinnycheek Lanternfish foraging on zooplankton throughout the night, while rapidly digesting the preceding nocturnal meal in the warm mesopelagic region. We hypothesize that the constrained epipelagic distribution of zooplankton and the unusual warm waters of the Red Sea force the whole population to ascend and feed in epipelagic waters every night, as the prey-ration eaten each night is fully digested at mesopelagic depths during daytime.
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seasonal variations in vertical migration of glacier Lanternfish benthosema glaciale
Marine Biology, 2012Co-Authors: Eivind Dypvik, Anders Rostad, Stein KaartvedtAbstract:The seasonal variations in glacier Lanternfish (Benthosema glaciale) vertical distribution and diel vertical migration (DVM) were studied by use of a bottom-mounted upward-facing 38 kHz echo sounder deployed at 392 m depth and cabled to shore in Masfjorden (~60°52′N, ~5°24′E), Norway. Acoustic data from July 2007–October 2008 were analyzed, and scattering layers below ~220 m during daytime were attributed to glacier Lanternfish based on net sampling in this, and previous studies, as well as from analysis of the acoustic data. At these depths, three different diel behavioral strategies were apparent: normal diel vertical migration (NDVM), inverse DVM (IDVM), and no DVM (NoDVM). NoDVM was present all year, while IDVM was present in autumn and winter, and NDVM was present during spring and summer. The seasonal differences in DVM behavior seem to correlate with previously established seasonal distribution of prey. We hypothesize that in regions with seasonally migrating zooplankton, such as where calanoid copepods overwinter at depth, similar plasticity in DVM behavior might occur in other populations of Lanternfishes.
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inverse vertical migration and feeding in glacier Lanternfish benthosema glaciale
Marine Biology, 2012Co-Authors: Eivind Dypvik, Stein Kaartvedt, Thor A KlevjerAbstract:A bottom-mounted upward-facing 38-kHz echo sounder was deployed at ~400 m and cabled to shore in Masfjorden (~60°52′N, ~5°24′E), Norway. The scattering layers seen during autumn (September–October) 2008 were identified by trawling. Glacier Lanternfish (Benthosema glaciale) were mainly distributed below ~200 m and displayed three different diel behavioral strategies: normal diel vertical migration (NDVM), inverse DVM (IDVM) and no DVM (NoDVM). The IDVM group was the focus of this study. It consisted of 2-year and older individuals migrating to ~200–270 m during the daytime, while descending back to deeper than ~270 m during the night. Stomach content analysis revealed increased feeding during the daytime on overwintering Calanus sp. We conclude that visually searching glacier Lanternfish performing IDVM benefit from the faint daytime light in mid-waters when preying on overwintering Calanus sp.
Rudy J. Kloser - One of the best experts on this subject based on the ideXlab platform.
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Micronekton assemblages and bioregional setting of the Great Australian Bight: A temperate northern boundary current system
Deep-sea Research Part Ii-topical Studies in Oceanography, 2018Co-Authors: Adrian Flynn, Rudy J. Kloser, C. SuttonAbstract:Abstract A multi-disciplinary pelagic ecosystem study of the Great Australian Bight (GAB) examined the micronekton communities and bioregionalisation in this area that harbours significant predator populations. Micronekton community structure and biomass differed between the eastern and central regions of the GAB. Regional differences were mainly driven by relatively high abundance of krill (Nematoscelis megalops, Nyctiphanes australis and Euphausia similis) in east GAB and high abundance of Maurolicus australis and chaetognaths in central GAB. Central GAB was also characterised by relatively high abundance of gelatinous zooplankton and small-bodied cephalopods. Lanternfishes were used as a model pelagic group to investigate the bioregional setting of the GAB. The analyses indicated that the oceanic habitats of the GAB had bioregional affinities with the subtropical Indian Ocean. However, over the continental slope, the east GAB had bioregional affinities with the Subtropical Convergence and grouped with western and southern Tasmania and the southern Tasman Sea. Lanternfish assemblage groups were compared against existing regionalisations that are based on physicochemical variables and the Delphi Method. No single existing scheme suitably reflected Lanternfish assemblage distributions, but parsimonious boundaries from existing schema were identified. This study demonstrates that the central GAB, where oil-and-gas exploration occurs alongside Marine Protected Area management, needs to be considered as a separate bioregion to the east GAB for the purposes of identifying conservation values and monitoring requirements.
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Cross-basin heterogeneity in Lanternfish (family Myctophidae) assemblages and isotopic niches (δ13C and δ15N) in the southern Tasman Sea abyssal basin
Deep Sea Research Part I: Oceanographic Research Papers, 2012Co-Authors: Adrian Flynn, Rudy J. KloserAbstract:Abstract A cross-basin (longitudinal) study of Lanternfishes in the southern Tasman Sea abyssal basin during the austral winter of 2008 and 2009 found that mean biomass in the Western sector was higher than that in the Eastern sector, corresponding with cross-basin patterns in oceanographic heterogeneity and productivity. Dominant species over the abyssal basin differed from those previously recorded over the neighbouring continental slope. Vertical biomass profiles indicated diffuse night-time distributions in the Central sector and extensive diel vertical migrations in the Eastern sector. In the Western sector, macrocrustacean δ13C values were significantly higher, and δ15N significantly lower, than those in the Eastern sector. The results indicate a cross-basin difference in the primary productivity environment and 15N enrichment at the base of the foodweb. The cross-basin pattern in Lanternfish δ15N values mirrored that for macrocrustaceans and was not correlated with standard length. Lanternfish δ13C values did not differ between sectors, but there were depth-wise differences, with values in the shallowest stratum (0–200 m) significantly higher than those in the deepest stratum (800–1000 m). Calculated trophic levels (TLs) of Lanternfishes spanned the third trophic level and marked niche segregation was evident in the Eastern (mean TL 3.0–3.9) and Central (mean TL 2.5–3.6) sectors. Together, the results suggest that the Eastern and Western sectors are distinct sub-basin scale pelagic habitats, with implications for ecosystem modelling and future monitoring.
Hiroki Yasuma - One of the best experts on this subject based on the ideXlab platform.
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Target strength of the Lanternfish, Stenobrachius leucopsarus (family Myctophidae), a fish without an airbladder, measured in the Bering Sea
ICES Journal of Marine Science, 2006Co-Authors: Hiroki Yasuma, Yoshimi Takao, Kouichi Sawada, Kazushi Miyashita, Ichiro AokiAbstract:Yasuma, H., Takao, Y., Sawada, K., Miyashita, K., and Aoki, I. 2006. Target strength of the Lanternfish, Stenobrachius leucopsarus (family Myctophidae), a fish without an airbladder, measured in the Bering Sea. e ICES Journal of Marine Science, 63: 683e692. This paper reports theoretical values of target strength (TS) for the Lanternfish Stenobrachius leucopsarus, a fish without an airbladder, which dominates the Subarctic marine mesopelagic fish community. Two models for liquid-like slender bodies, the general prolate-spheroid model (PSM) and the deformed-cylinder model (DCM), were used to compute the TS of the fish relative to its orientation. The relative mass density g and the sound speed h in seawater were measured and used in both models. To confirm the appropriateness of the models, tethered experimental measurements were carried out at 38 kHz for five specimens. The value of g measured by the density-bottle method was very low (1.002e1.009) compared with that of marine fish in general. The value of h measured by the time-average approach was 1.032e1.039 at the water temperature at which S. leucopsarus is found. TS-fluctuation patterns against fish orientation (the TS pattern) estimated from the DCM and PSM were in good agreement in the area of their main lobes. Both models reproduced the main lobes of the measured TS patterns in near-horizontal orientation (
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target strength of the Lanternfish stenobrachius leucopsarus family myctophidae a fish without an airbladder measured in the bering sea
Ices Journal of Marine Science, 2006Co-Authors: Hiroki Yasuma, Yoshimi Takao, Kouichi Sawada, Kazushi Miyashita, Ichiro AokiAbstract:Yasuma, H., Takao, Y., Sawada, K., Miyashita, K., and Aoki, I. 2006. Target strength of the Lanternfish, Stenobrachius leucopsarus (family Myctophidae), a fish without an airbladder, measured in the Bering Sea. e ICES Journal of Marine Science, 63: 683e692. This paper reports theoretical values of target strength (TS) for the Lanternfish Stenobrachius leucopsarus, a fish without an airbladder, which dominates the Subarctic marine mesopelagic fish community. Two models for liquid-like slender bodies, the general prolate-spheroid model (PSM) and the deformed-cylinder model (DCM), were used to compute the TS of the fish relative to its orientation. The relative mass density g and the sound speed h in seawater were measured and used in both models. To confirm the appropriateness of the models, tethered experimental measurements were carried out at 38 kHz for five specimens. The value of g measured by the density-bottle method was very low (1.002e1.009) compared with that of marine fish in general. The value of h measured by the time-average approach was 1.032e1.039 at the water temperature at which S. leucopsarus is found. TS-fluctuation patterns against fish orientation (the TS pattern) estimated from the DCM and PSM were in good agreement in the area of their main lobes. Both models reproduced the main lobes of the measured TS patterns in near-horizontal orientation (<� 20(), and they were considered to be effective in measuring the TS of S. leucopsarus in a horizontal (swimming) position. After these comparative experiments, we computed the TS of 57 fish (27.8e106.9 mm) at 38, 70, 120, and 200 kHz, using the DCM. A plot of body length (in log scale) against TS showed a non-linear relationship at all frequencies. S. leucopsarus had a very low TS (<� 85 dB, TScm), suggesting that acoustic assessment would be highly sensitive, especially when the proportion of small fish is high (e.g. L/l < 2), and an appropriate frequency should be considered that takes into account both the length composition and the depth of occurrence.
