Differences in fine-scale structure and composition of zooplankton between mixed and stratified regions of Georges Bank

Norrbin, Fredrika; Davis, Cabell S.; Gallager, Scott M.

doi:10.1016/s0967-0645(96)00046-x

Cited by 46 publications

(31 citation statements)

References 21 publications

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“…m -3 in Tokyo Bay. Abundance estimates based on VPR data have demonstrated high densities of small hydromedusae (Norrbin et al 1996, Broughton & Lough 2006. Broughton & Lough (2006) described depth distributions of Obelia sp.…”

Section: Discussionmentioning

confidence: 99%

“…Video plankton recorder (VPR) systems enable classification and quantification of plankton, and are useful in resolving distributional structures of plankton at a broad range of spatial scales (Davis et al 1992, Benfield et al 1996, Norrbin et al 1996. The VPR is a noninvasive sampling system, and delicate organisms like gelatinous zooplankton, egg-bearing copepods, and colonial plankton can be surveyed and quantified accurately in their natural orientations without being damaged.…”

Section: Introductionmentioning

confidence: 99%

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Fine-scale layer of hydromedusae is revealed by video plankton recorder (VPR) in a semi-enclosed bay in northern Norway

Jacobsen¹,

Norrbin²

2009

Mar. Ecol. Prog. Ser.

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High resolution images of zooplankton organisms were recorded in situ using a digital autonomous video plankton recorder (VPR) in a semi-enclosed bay in northern Norway. Data from vertical VPR profiles was used to estimate the depth distribution and abundance of zooplankton along a bay-wide grid. Images were recorded simultaneously with hydrographical data, and the spatial distribution of different organisms was related to several water column characteristics, such as chlorophyll a, density, and buoyancy frequencies. In June, unusually high abundances of hydromedusae (Rathkea octopunctata and Obelia sp.) were located in a fine-scale layer of a few metres thickness. This layer could be associated with relatively high buoyancy frequencies, reflecting a density gradient present throughout the entire sampling area. Aggregation of hydromedusae around density discontinuities may have enabled retention of medusae in the bay. Ctenophores and appendicularians were distributed above the medusae layer, while peaks of copepod abundance were found outside the layer boundaries. We suggest that the bloom of R. octopunctata was initially caused by liberation of new medusae from successful benthic hydroid colonies, and that proliferation of this species was sustained by asexual, manubrial budding in the medusae stage. KEY WORDS: Zooplankton · Hydromedusae · Video plankton recorder · Vertical distributionResale or republication not permitted without written consent of the publisher

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Fine-scale layer of hydromedusae is revealed by video plankton recorder (VPR) in a semi-enclosed bay in northern Norway

Jacobsen¹,

Norrbin²

2009

Mar. Ecol. Prog. Ser.

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“…Over the last decade, new optical imaging devices have been developed that are allowing high-resolution distributions of plankton taxa to be determined (Video Plankton Recorder, VPR, Davis et al 1992a,b;Underwater Video Profiler, Gorsky et al 1992, 2000Ichthyoplankton Recorder, Froese et al 1990, Lenz et al 1995FlowCam, Sieracki et al 1998;in situ video, Tiselius 1998;Shadow Image Particle Profiling Evaluation Recorder, SIPPER, Samson et al 2001). The VPR has been used to identify planktonic taxa in real time (Davis et al 2004(Davis et al , 2005, measure distributions nearly continuously over a broad range of scales , and quantify abundance and biomass of delicate plankton and particulate matter (Davis et al 1992b, Norrbin et al 1996, Ashjian et al 2001, in press a, in press b). Initial data from the VPR and other optical samplers required manual processing, a tedious and time-consuming effort.…”

Section: Introductionmentioning

confidence: 99%

Automatic plankton image recognition with co-occurrence matrices and Support Vector Machine

Hu¹,

Davis²

2005

Mar. Ecol. Prog. Ser.

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A long-standing problem in plankton ecology is sparseness of taxa-specific data. New optical imaging systems are becoming available which can acquire high-resolution data on the abundance and biomass of plankton taxa. The Video Plankton Recorder (VPR) has been designed and used for automatic sampling and visualization of major planktonic taxa at sea in real time, providing high-resolution data over a broad range of scales. Although these optical systems produce digital images of plankton that can be automatically identified by computer, the limited accuracy of automatic classification methods can reduce confidence in subsequent abundance estimates, especially in areas where a taxon is in low relative abundance. This paper describes an improved classification system for automatic identification of plankton taxa from digital images. Classifiers are trained from a set of images that were classified by human experts. The data set used to verify the classification system contains over 20 000 planktonic images manually sorted into 7 different categories. The new method uses co-occurrence matrices (COM) as the feature, and a Support Vector Machine (SVM) as the classifier. This new method is compared against a previous plankton recognition system, which used moment invariants, Fourier descriptors and granulometry as features and a learning vector quantization neural network as a classifier. The new method reduced the classification error rate from 39 to 28%. Subsequent plankton abundance estimates are improved by more than 50% in regions of low relative abundance. In general, the reduction in classification error was due to a combination of the use of COM and SVM.

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“…New insights into biological/physical mechanisms controlling plankton abundance have been made using the VPR (e.g., Ashjian et al accepted-a, 2001, accepted-b;Benfield et al 2000Benfield et al , 1996Benfield et al , 1998Davis et al 1996Davis et al , 1992bDavis et al , 2004Gallager et al 1996Gallager et al , 2004Norrbin et al 1996), and high abundance of fragile plankton (colonial algae and protozoa) have been found that significantly impact estimates of oceanic production and consumption (e.g., Dennett et al 2002;Sieracki et al 1998;Villareal et al 1999). The increased capabilities of the VPRII and its availability to the research community will foster further exploration of plankton ecology in marine and freshwater habitats.…”

Section: Discussionmentioning

confidence: 99%

A three-axis fast-tow digital Video Plankton Recorder for rapid surveys of plankton taxa and hydrography

Davis

Thwaites

Gallager

et al. 2005

Limnol. Oceanogr. Methods

135

101

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A new Video Plankton Recorder (VPRII) has been developed for rapid surveys of plankton and seston in the size range of 100µm-1cm. The VPRII system includes: 1) a high-resolution digital camera (1Mpixel, 10-bits, 30Hz frame-rate), 2) a fast towfish capable of tow speeds up to 12 knots and 3-axis motion for automatic undulation and ship-wake avoidance, small diameter tow cable and winch for deployment on coastal vessels, and 3) new interface software (Visual Plankton) for automatic identification of plankton to major taxa and visualization of these taxa together with hydrographic data in real time. Camera and strobe optics are laboratory-adjusted to select the field-of-view (5-20mm), and depth-of-field is objectively calibrated using a tethered organism (e.g., copepod) and automatic focus-detection software. The VPRII towfish comprises a fuselage, a fixed main wing, and three servo-controlled tail fins: port and starboard for dive, climb, and roll control and rudder for lateral movement. Placement of the strobe (starboard wing-tip), camera (fuselage nose), and cantilevered tow-bridle minimize disturbance of the imaged volume. Compared with typical net surveys in shelf areas, the VPRII counts more plankton per station, quantifies ubiquitous fragile forms, automatically identifies plankton to major taxa and measures their size, quantifies scales of patchiness down to a few cm, and displays high-resolution distributions of plankton taxa and hydrography while underway. The VPRII is available to researchers via the Woods Hole Oceanographic Institution ship instrumentation pool. AcknowledgmentsWe thank the officers and crew of the R/V Oceanus for their support during field tests of the new VPR system. Engineers Pierre Tillier, Ken Peal, Nick Witzel, Ed Hobart, and Steve Faluotico made valuable contributions to the design and construction of the new VPR. Others involved in this project include

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Differences in fine-scale structure and composition of zooplankton between mixed and stratified regions of Georges Bank

Cited by 46 publications

References 21 publications

Fine-scale layer of hydromedusae is revealed by video plankton recorder (VPR) in a semi-enclosed bay in northern Norway

Fine-scale layer of hydromedusae is revealed by video plankton recorder (VPR) in a semi-enclosed bay in northern Norway

Automatic plankton image recognition with co-occurrence matrices and Support Vector Machine

A three-axis fast-tow digital Video Plankton Recorder for rapid surveys of plankton taxa and hydrography

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