Is citizen science a valid tool to monitor the occurrence of jellyfish? The spot the jellyfish case study from the Maltese Islands

Abstract

The potential of citizen science in monitoring transient biological phenomena occuring over large spatial scales, such as the blooming of jellyfish species, has received increased acknowledgement in recent years. The Spot the Jellyfish citizen science campaign was launched by the International Ocean Institute and by the University of Malta in the summer of 2010, with thousands of jellyfish spotting reports having been submitted by sea-users through the campaign website, social media site, smart phone app or even through email, since then. The 2011-2015 submitted jellyfish reports were analysed, besides a number of water quality parameters (temperature, salinity, chlorophyll a content, nutrient and phytoplankton concentration), whose values were gleaned for the marine area of interest through online satellite water quality data portals. The main aim of this exercise was to seek to identify possible relationships, through a variety of univariate and multivariate statistical techniques, between the distribution of submitted campaign jellyfish records and the same water quality parameters. Possible bias introduced in the report database through artefacts such as differences in bay frequentation were addresses through normalisation procedures. Spatial differences in the abundance of jellyfish reports submitted along different part of the Maltese coastline emerged, with the highest number of such reports having been submitted along the north-eastern coastline of the island of Malta, and jellyfish sighting reports correlated well with the values of the selected water quality values. Despite this, our results indicate that besides the selected water quality parameters, other forces, possibly hydrodynamic ones, were contributing to the recorded spatial variability in jellyfish occurrence.