Recent Advances in Visual Sensing and Machine Learning Techniques for
in-situ Plankton-taxa Classification
Abstract
The assessment of planktonic organisms is a prevailing task in marine
ecology and oceanography as planktons form the principal food source for
consumers at higher trophic levels. Reliable estimates on the production
at the lowermost trophic levels are thus an integral part for the
management of marine ecosystems. Traditional plankton sampling and
analysis are limited in their spatial and temporal context of the
organisms’ environment, which are often critical clues to a biologist
for its habitation. In addition, ship-based sampling as described leads
to a high level of uncertainty in the estimation, since point
measurements that are intermittent in space and time are used (Reid et
al 2003; Lermusiaux 2006; Vannier 2018). A disruptive change in approach
to tackle this problem is currently taking place, enabled by the use of
autonomous robots (Henthorn et al 2006) and augmented by visual sensing
for real-time analysis (Ohman et al 2019; AILARON 2019). Approaches
providing taxonomy estimates from time-series image analysis (Sosik and
Olson 2008) or via computer simulations (Roberts and Jaffe 2007), with
the recent advances in deep learning, enabled by the computational power
of multicore CPUs and GPUs, made possible processing and classification
of large datasets while learning higher level representations. Enhanced
traditional machine learning methods are driven by multiple kernel
learning, where general features are combined with robust features and
new types from multiple views are defined in order to generate multiple
classifiers (Py et al 2016; Dai et al 2016; Lee et al 2016; Moniruzzaman
et al 2017). In this paper, we present recent DL methods for microscopic
organisms’ identification and classification. A proposed DL architecture
(cf. figure 2) reported an accuracy of 95% as opposed to (90% - 93%
cf. table 2) achieved by the state-of-the-art networks: ZooplanktoNet,
VGGNet, AlexNet, ResNet, and GoogleNet, while training over a labeled
dataset of extracted objects from images of plankton organisms captured
in-situ (cf. table 1). COAPNet is embedded into a light-weight
autonomous vehicle (LAUV) for real-time in-situ plankton taxa
identification and classification. The LAUV in turn utilizes the
feedback from the image analysis to constantly update a probability
density map that further enables an adaptive sampling process.