The ZooCAM, a new in-flow imaging system for fast onboard counting, sizing and classification of fish eggs and metazooplankton

Abstract

In this paper we present the ZooCAM, a system designed to digitize and analyse on board large volume samples of preserved and living metazooplankton (i.e. multicellular zooplankton) and fish eggs > 300 µm ESD. The ZooCAM has been specifically designed to overcome the difficulties to analyse zooplankton and fish eggs in the framework of the PELGAS survey, and provide high frequency data. The ZooCAM fish eggs counts were comparable to those done with a dissecting microscope. The ZooCAM enabled the accurate prediction and fast on board validation of staged anchovy and sardine eggs in almost real time after collection. A comparison with the ZooScan, on a more complex zooplanktonic community, provided encouraging results on the agreement between the 2 instruments. ZooCAM and ZooScan enabled the identification of similar communities and produced similar total zooplankton abundances, size distributions, and size spectra slopes, when tested on the same samples. However these results need to be further refined due to the small number of samples used to compare the two instruments. The main ZooCAM drawback resides in a slight but sensible underestimation of abundances and sizes, and therefore individual and community biovolumes. The ZooCAM have been successfully deployed over 4 years, on numerous surveys without suffering any major failure. When used in line with the CUFES it provided high resolution maps of staged fish eggs and zooplanktonic functional groups. Hence the ZooCAM is an appropriate tool for the development of on board, high frequency, high spatial coverage zooplanktonic and ecosystemic studies. Highlights ► The ZooCAM is a new inflow imaging system for fast onboard counting, sizing and classification of fish eggs and metazooplankton. ► The ZooCAM has been used on-board for 4 years without suffering any failure and enabled the analysis ∼10,000 samples so far (CUFES, WP2 and other plankton nets). ► The ZooCAM provided staged fish eggs counts that were equivalent to those traditionally done by microscopic examination. These data were used for 2016 and 2017 anchovy and sardine stocks estimations in the Bay of Biscay (DEPM method) ► The ZooCAM enable the real time, on-board, imaging of complex communities zooplankton samples and provide results comparable to on-land, well established counterpart, the ZooScan. ► The ZooCAM is a valuable tool to improve zooplanktonic studies, in term of spatial coverage and temporal frequency, to perform ecosystemic studies.

Characterization of sound scattering layers in the Bay of Biscay using broadband acoustics, nets and video

“…This difficulty (here, one net out of two sampled them) can lead to an underestimation of pneumatophore size diversity and density. The use of ZooCAM imaging [35] was essential for detecting their presence and counting the small siphonophore pneumatophores, too small to be seen on in situ video recordings. The in situ video recordings were essential to ascertain the presence and count large siphonophores [59].…”

“…Micronekton and gelatinous zooplankton caught by the MIK nets were identified and measured immediately after collection, or later in the laboratory after formalin fixation (4%). Multinet mesozooplankton samples were also imaged immediately after collection using the ZooCAM in-flow imaging system [35]. Mesozooplankton between 1 and 3 mm from the MIK samples were imaged using a ZooScan [36] after formalin fixation (4%) in the laboratory.…”

Globally Consistent Quantitative Observations of Planktonic Ecosystems

“…When using proxies for particles and plankton properties (e.g., bio-optics and bio-acoustics), periodic ground-truth ensures biases are constrained. Colas et al, 2018), and the inter-comparison has often taken place long after the introduction of a new device (e.g., Schultes and Lopes, 2009;Reynolds et al, 2010;García-Comas et al, 2011;Forest et al, 2012;Thyssen et al, 2014;Le Bourg et al, 2015). 6.…”

Advancing Observation of Ocean Biogeochemistry, Biology, and Ecosystems With Cost-Effective in situ Sensing Technologies

“…For organisms larger than 100 µm, the number of available sensors has increased drastically over the last decade and several are available at reasonable costs (<$100k) with a high capacity of data production. The examples include the FlowCam macro (Sieracki et al, 1998), Video Plankton Recorder I and II (Batten et al, 2003), ZooSCAN (Gorsky et al, 2010), Underwater Vision Profiler (Picheral et al, 2010), and in situ Ichthyoplankton Imaging System (ISIIS) (Cowen and Guigand, 2008) and an onboard system (Colas et al, 2018). However, two identified main limits have high cost associated with operating the instruments, if not in the capital cost itself.…”