Citation: Newcomer, K., Tracy, B.M., Chang, A.L., Ruiz, G.M., 2019. Evaluating Performance of Photographs for Marine Citizen Science Applications. Frontiers in Marine Science 6. https://doi.org/10.3389/fmars.2019.00336
Large scale research efforts can be challenging due to time, financial and personnel constraints. However, long-term monitoring is important to observe environmental changes that may occur over longer periods of time. In addition, there is a growing need to monitor coastal communities for threats from climate change, pollution and invasive species. Citizen scientists can help with these large-scale efforts. Citizen science is the involvement of the general public in collecting and analyzing scientific data. As scientists realize the value of involving the general public in their work, engagement with citizen scientists continues to rise.
The authors of this study discuss how citizen science engagement is likely to be high if the method is easily repeatable and quickly executed. Lucky for them, examining photographs fits this bill. In this technology-aged world, citizen science involvement using photography is relatively easy because anyone with a camera can contribute to science. In fact, the authors explain how monitoring for invasive species is an excellent opportunity for citizen scientists to make significant contributions. Have you heard of the lionfish? Or the zebra mussel? They are the poster children for invasive species. Non-native species continue to be a leading threat to ecosystems across the globe; however, it is difficult for scientists to keep track of organisms on every coastline of the world. Thus, citizen scientists provide the human power to keep tabs on those pesky invaders!
In previous studies, citizen scientists have participated in photographic analyses like the ones described in this study. However, the authors note these past studies have relied solely on these photographic analyses without comparing them to live examinations by trained scientists. Here, the authors evaluate the use of photographs to accurately characterize marine invertebrate communities in order to develop a citizen science program with two main goals: 1) detecting arrivals of invasive species and 2) documenting community response to change. They compared the accuracy of photographs to live, field-based analyses and determined which research questions were best answered by volunteers without specific taxonomic expertise.
The how and what…
A common method to study marine invertebrates and invasions is to use settlement panels as passive sampling devices. These panels are good because most marine invertebrates live on hard substrate habitats, so the panels act as an extension of their home. Panels are also very easy to photograph and deploy. In this study, panels were hung from various points in the water around SF Bay and deployed for three months. Upon retrieval, three measurement methods were compared on each of the 200 panels: live point counts, photo-based point counts, and an exhaustive live search. For the live point counts, the panels were examined with a point count grid under a microscope. This means that there is a grid laid over the panel and each time there is an intersection in the grid, the organisms below this point is identified and counted.
The same procedure was done for the photo-based point counts except that the photographs were used with a point count grid instead of the live panels. Lastly, for the exhaustive live search, a trained taxonomist surveyed the entire plate and identified each organism they found.
Across the 5-year observational study, the authors identified four non-native target taxa that are known to occur in SF Bay and are spreading to other global regions. Target taxa, in other words refers to species of interest to scientists and policy makers. These target taxa spanned across four functional groups, or collection of organisms included : “Encrusting Byozoa”, “Soft Bryozoa”, “Solitary Tunicata”, and “Colonial Tunicata”. The authors used various models to analyze their data. Overall, they found that photo-based analyses produced lower species richness counts than field-based analyses. In addition, across all years analyzed, 31 species were observed in the field that were not identified in photographs. There was a good match between photographic analyses and live examination for the four target taxa functional groups identified by the authors. This matchup of photographs to live counts for target taxa is especially helpful for policy makers as invasive species continue to spread. So if citizen scientists can help identify these invaders, then they are able to make substantial contributions to invasive species research efforts.
The authors found that examining live organisms in the field provided more accurate data, with higher richness and diversity measurements than photographic measurements. Unfortunately, species-specific measurement tools such as diversity and richness cannot be reliably approximated from photographs for marine invertebrates. However, photographic analyses were able to capture the number of highly recognizable target taxa and are thus good for broad scale comparisons of functional groups. In addition, the presence/absence trends were the same between photos and live analyses. This means that if an organism was found on the live plate, it was also found in the photograph. Or vice versa: if it wasn’t found on the live plate, it also wasn’t found in the photo. Community composition analyses rely heavily on abundance information and are easily obtainable from photographs, so for community level observations, photographs are a great tool to engage with citizen scientists.
To sum it up…
In this study, the authors found that the most reliable uses for photographic analyses are 1) the identification of specific target taxa that are known invasive species and 2) the documentation of large shifts in community composition that may serve as indicators of environmental change. It is also important to note that the two “best uses” for photographs reduce the expectation of citizen scientists to become expert taxonomists. Even though photographic analyses can help long-term environmental monitoring efforts, photographs will continue to miss many rare and small species, even with increased effort. Thus, the authors recommend that citizen scientists focus on collecting data on species within well-sampled, large and easily-identifiable groups. They encourage scientists who want to engage with citizen scientists to carefully design questions that do not rely on species level community analysis.
I love writing of all kinds. As a PhD student at the Graduate School of Oceanography (URI), I use using genetic techniques to study phytoplankton diversity. I am interested in understanding how environmental stressors associated with climate change affect phytoplankton community dynamics and thus, overall ecosystem function. Prior to graduate school, I spent two years as a plankton analyst in the Marine Invasions Lab at the Smithsonian Environmental Research Center (SERC) studying phytoplankton in ballast water of cargo ships and gaining experience with phytoplankton taxonomy and culturing techniques. In my free time I enjoy making my own pottery and hiking in the White Mountains (NH).