Bay watch: Using unmanned aerial vehicles (UAV’s) to survey the box jellyfish Chironex fleckeri

Abstract

Biological investigations on free ranging marine species are regarded as challenging throughout the scientific community. This is particularly true for ‘logistically difficult species’ where their cryptic natures, low abundance, patchy distributions and difficult and/or dangerous sampling environments, make traditional surveys near impossible. What results is a lack of ecological knowledge on such marine species. However, advances in UAV technology holds potential for overcoming these logistical difficulties and filling this knowledge gap. Our research focused on one such logistically difficult species, the Australian box Jellyfish ( Chironex fleckeri ), and we investigated the capacity of consumer grade UAV technology to detect this, highly venomous, target species in the inshore waters of Northern Queensland Australia. At two sites in the Weipa area, we utilized video analysis, visual count comparisons with a netted animal tally, and evaluated the role of associated environmental conditions, such as wind speed, water visibility and cloud cover on jellyfish detection rates. In total fifteen, 70 meter transects were completed between two sites, with 107 individuals captured. Drone success varied between the two sites with a significant difference between field and post-field (laboratory) counts. Animal size and cloud cover also had significant effects on detection rates with an increase in cloud cover and animal size enhancing detection probability. This study provides evidence to suggest drone surveys overcome obstacles that traditional surveys can’t, with respect to species deemed logistically difficult and open scope for further ecological investigations on such species.

Genetic Detection and a Method to Study the Ecology of Deadly Cubozoan Jellyfish

“…These gaps are a result of the challenges associated with detecting and subsequently studying these animals in their natural environment, resulting from their spatial and temporal variability, transparency, cryptic nature and the fact that they commonly reside in waters of low visibility [13]. Multiple techniques have been utilised to detect jellyfish, including in situ visual observations [14,15], various styles/sizes of netting [16][17][18][19], light attraction techniques [19][20][21], acoustics [22,23], and most recently drones [24][25][26]. Each method has 2 of 20 benefits and limitations, depending on the application and ambient conditions.…”

Using Drones to Measure Jellyfish Density in Shallow Estuaries

“…Drone sampling should be conducted in good weather and only over calm water to reduce sun reflections and wave turbulence at the surface that may interfere with the detection of jellyfish [28]. Unrelated clutter is likely to either overestimate the density of jellyfish (when light spots are mistaken as jellyfish by the software) or underestimate it when a high brightness make the jellyfish barely visible from above.…”

“…The biomass of jellyfish can also be assessed from drone images with species that have a known size-weight relationship [27]. In addition, drones can overcome the limitations of traditional methods when studying cryptic and dangerous species [28] and could be a cost-effective alternative for observing large species [29].…”

Evaluating the effectiveness of drones for quantifying invasive upside-down jellyfish (Cassiopea sp.) in Lake Macquarie, Australia

“…Drones have been effectively used to monitor pelagic jellyfish, such as Catostylus mosaicus [ 36 ], Aurelia sp. [ 10 ] and Chironex fleckeri [ 37 ], and to detect the presence of Cassiopea in aquaculture systems [ 38 ]. However, the use of drones for long-term monitoring of sedentary Cassiopea in their natural environment has not yet been explored.…”