FTV: a sonar for tracking macrozooplankton in three dimensions

Jaffe, Jules S.; Reuss, Edward; McGehee, Duncan E.; Chandran, G.

doi:10.1016/0967-0637(95)00030-a

Cited by 38 publications

(22 citation statements)

References 14 publications

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“…An alternative approach uses acoustic methods to track and quantify individual particles. The FTV, 1.6-MHz echo sounder for in situ zooplankton studies (Table 1, Jaffe et al 1995) is a multibeam imaging system, designed to count and track individual targets (scatterers) in three-dimensional space. Major advantages of the FTV are higher acoustic frequency and high spatial and temporal resolution.…”

Section: Methodsmentioning

confidence: 99%

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Diel pattern with abrupt crepuscular changes of zooplankton over a coral reef

Yahel

Berman

et al. 2005

Limnology & Oceanography

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We studied zooplankton abundance and emergence patterns over coral reefs in the Gulf of Aqaba using highresolution acoustics (multibeam sonar, FTV, 1.6 MHz, and WH600 ADCP, 614 KHz), emergence traps, and an underwater pump, supplemented with field observations on feeding behavior of zooplanktivorous fish. The zooplanktonic community over coral reefs is a complex and highly dynamic mixture of pelagic plankton advected into the reef, larvae and eggs released by benthic animals, and demersal plankton. At sunset (0 Ϯ4 min, mean Ϯ95% confidence interval) acoustic back-scattering intensity and zooplankton biomass started to increase rapidly. In contrast with this ascent, the predawn decline began much earlier during the dark (82 Ϯ5 min before sunrise) and terminated before sunrise. This light-dependent diel behavior was highly consistent throughout the year, regardless of seasonal and environmental changes. Smaller zooplankters (500-700 m) ascended first and demersal zooplankton accounted for most of the increase in zooplankton soon after sunset. Surprisingly, the emergence of zooplankton occurred while large schools of diurnal zooplanktivorous fish were still foraging in the water column. However, at that time, prey-capture efficiency by the fish is greatly reduced and corals had not yet expanded their tentacles, producing an optimal window of opportunity of low risk for emergence.Diel vertical migration (DVM) is one of the most conspicuous features of zooplankton behavior, occurring in di-

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Section: Methodsmentioning

confidence: 99%

“…As a consequence, the final insonifying volume available for analysis was 0.082 m 3 . Signal processing was carried out as in Jaffe et al (1995) using a threshold of Ϫ95 dB.…”

Section: Acoustic Measurements By a Multibeam Sonar (Ftv)-atmentioning

confidence: 99%

Diel pattern with abrupt crepuscular changes of zooplankton over a coral reef

Yahel

Berman

et al. 2005

Limnology & Oceanography

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“…Technological advances (e.g. Jaffe et al 1995) should soon enable in situ swimming speeds of individual fish larvae to be determined without the immediate presence of an observer. Until then, observations on carefully chosen species by divers, such as those presented here, are the best, and seemingly a valid, measure of the swimming abilities of coral-reef fish larvae.…”

Section: But R2 Decreased To 035 This Reflects the Variability Inmentioning

confidence: 99%

In situ swimming speeds of the late pelagic larvae of some Indo-Pacific coral-reef fishes

Leis¹,

Carson-Ewart²

1997

Mar. Ecol. Prog. Ser.

189

173

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S\~lmrnlng speeds of the late-stage, pelaglc larvae of coral-leef flshes were measured in situ near Llzard Island on Australia's Great Barrler Reef, and Ranglroa Atoll, Tuamotu Islands, French Polynes~a d u n n g 1995-96 Larvae were captured w~t h llght traps and crest nets, and released indiv~du-ally In open water They were then followed by SCUBA d~v e r s , normally for 10 mm, and their speed was measured w~t h a m o d~f~e d plankton-net flow meter and a stop watch Swlmmlng speeds of 260 lalvae of 50 specles In 15 famll~es of mostly perclform reef f~s h e s are presented Most measurements were for pomacentnds (8 genera 16 specles, 127 ~n d~v i d u a l s ) , apogonids (1 genus, -5 specles, 18 1nd1-vlduals), chaetodontids (3 genera. 8 specles, 49 ~ndlviduals), lethrlnlds (1 genus, -4 specles, 11 lndivlduals), nemipterlds ( l genus, 2 specles, 10 ~ndlvlduals), serranlds (2 genera, 2 specles, 14 md~vlduals) and acanthurlds (2 genera, -4 specles 13 ~n d~v l d u a l s )Numbers of lndlvlduals per specles ranged from 1 to 25 Speeds were remarkably hlgh for such small flshes ( 0 7 to 5 5 cm) Average speed was 20 6 cm S ' (ranqe 2 to 65), or 13 7 body lengths s ' (range 2 to 34) SE fol specles wlth n > 4 ranged from 0 8 to 5 3 cm s ' 14 1 to 25 0 " 0 of mean speed), but speed of the fastest lndlvldual ot each specles averaged 144 "/o of mean speed A taxonom~c component was evident, with apogonlds the slowest (2 to 13 cm S l ) , followed by nemipterlds (10 cm s ') Speed of pomacentr~ds and chaetodontlds varled wldely among specles (7 to 35 cm s '), whereas acanthunds, lethrlnlds and s e r r a n~d s were fast ( l 9 to 55 cm S-') Except for apogonlds and nem~ptel-lds, nearly all specles had mean swlmming speeds greater than average ambient current speeds In the L~zard Island area Mean speed was positively correlated wlth size (slope 8 2, r2 = 0 43) when all taxa were lncluded but was not correlated wlth slze for the Pomacentndae and Chaetodontidae when each were considered alone The speeds reported here combined wlth data on swimming endurance recently reported by Stobutzk~ & Bellwood (1997. Mar Ecol Prog Ser 149 35-41) reveal remarkable swlmnling a b l h t~e s for late-stage pelaglc larvae of coral-reef flshes whlch could e~t h e r gleatly enhance d~spersal or eliminate it

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“…Two different acoustic instruments for observing behavior are the multibeam sonar, see, e.g., Jaffe et al ͑1995͒, and the split-beam echosounder ͑Brede et al, 1990;Ehrenberg and Torkelson, 1996͒. The multibeam sonar can handle several targets at a given range, but the resolution is limited by the number of beams and their opening angles.…”

Section: A the State Of The Artmentioning

confidence: 99%

Observing individual fish behavior in fish aggregations: Tracking in dense fish aggregations using a split-beam echosounder

Handegard

2007

The Journal of the Acoustical Society of America

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Acoustic instruments are important tools for observing the behavior of aquatic organisms. This paper presents a simple but efficient method for improving the tracking of closely spaced targets using a split-beam echosounder. The traditional method has been a stepwise approach from the detection of echoes, rejection of apparently multiple targets and then tracking the remainder. This is inefficient because the split-beam angles are not included in the initial detection; rather they are only used in the rejection criteria before the subsequent tracking. A simple track-before-detection method is presented, where the phase angles, echo intensities, ranges, and times are used simultaneously, resulting in better detection and tracking of the individual fish. Two test data sets were analyzed to determine the effectiveness of this method at discriminating individual tracks from within dense fish aggregations. The first data set was collected by lowering a split-beam transducer into a herring layer. The second data set, also collected with a split-beam transducer, was from a caged aggregation of feeding herring larvae. Results indicate the potential of target tracking, using a split-beam echosounder, as a tool for understanding interindividual behavior.

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FTV: a sonar for tracking macrozooplankton in three dimensions

Cited by 38 publications

References 14 publications

Diel pattern with abrupt crepuscular changes of zooplankton over a coral reef

Diel pattern with abrupt crepuscular changes of zooplankton over a coral reef

In situ swimming speeds of the late pelagic larvae of some Indo-Pacific coral-reef fishes

Observing individual fish behavior in fish aggregations: Tracking in dense fish aggregations using a split-beam echosounder

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