Abstract
Science is addressing global societal challenges, and due to limitations in research financing, scientists are turning to the public at large to jointly tackle specific environmental issues. Citizens are therefore increasingly involved in monitoring programs, appointed as citizen scientists with potential to delivering key data at near to no cost to address environmental challenges, therein fostering scientific knowledge and advising policy- and decision-makers. One of the first and most successful examples of marine citizen science in the Mediterranean is represented by the integrative and collaborative implementation of several jellyfish-spotting campaigns in Italy, Spain, Malta, and Tunisia starting in 2009. Altogether, in terms of time coverage, geographic extent, and number of citizen records, these represent the most effective marine citizen science campaigns thus far implemented in the Mediterranean Sea. Here, we analyzed a collective database merging records over the above four countries, featuring more than 100,000 records containing almost 25,000 observations of jellyfish specimens collected over a period of 3 to 7 years (from 2009 to 2015) by citizen scientists participating in any of the national citizen science programs included in this analysis. Such a wide citizen science exercise demonstrates a valuable and cost-effective tool to understanding ecological drivers of jellyfish proliferation over the Western and Central Mediterranean basins, as well as a powerful contribution to developing tailored adaptation and management strategies; mitigating jellyfish impacts on human activities in coastal zones; and supporting implementation of marine spatial planning, Blue Growth, and conservation strategies.
Highlights
Jellyfish have been acknowledged as a natural component of marine ecosystems since antiquity, as the fossil record shows that gelatinous blooms were already occurring several hundred millions of years ago [1,2]
In order to analyze which variables have a higher important role affecting the spatio-temporal dynamics of jellyfish, we focused on the average variable importance among the three machine learning algorithms
Sub-basin scale, our results demonstrate the potential of citizen science data for the unraveling of jellyfish temporal dynamics, as well as the identification of potential blooming areas of the most abundant jellyfish species, through habitat-modeling
Summary
Jellyfish have been acknowledged as a natural component of marine ecosystems since antiquity, as the fossil record shows that gelatinous blooms were already occurring several hundred millions of years ago [1,2]. Some coastal marine ecosystems may have been undergoing a long-term increase in jellyfish biomass proliferation in recent decades (e.g., the Mediterranean Sea [4,16,18,19,20]) This lack of data on gelatinous zooplankton is partly due to the fact that jellyfish were not targeted species in fisheries or oceanographic research, as they were poorly known by scientists and considered ecologically unimportant. Another reason behind such data deficiency is that the fragility of most gelatinous species and their patchy distribution makes conventional plankton nets inadequate for sampling this taxon: gelatinous organisms may be damaged beyond recognition, critically limiting the resulting information on species composition, abundance, and distribution [21,22]. Recent surveys and research campaigns on jellyfish relied on non-traditional data collection methods, including citizen science, to assess patterns of jellyfish diversity, abundance, seasonality, and distribution (e.g., shoreline surveys and stranding observations, aerial surveys, or interviews to stakeholders, among others [22,23,24,25,26,27])
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