As they emerge from freshwater ecosystems and take flight, aquatic insects play an important role for the surrounding terrestrial ecosystem. This pulse of resources out of the aquatic system and into the surrounding terrestrial ecosystem creates a rich food source for birds living near the water. With these important cross ecosystem subsidies, unfortunately, also come aquatic contaminants, such as mercury. The intricacies of these connections are often not well understood by non-scientists. In June and July 2018, we collected aquatic, terrestrial and emerged aquatic insects at four sites in Acadia National Park (Maine, USA). We worked with park visitors to collect invertebrates, allowing an opportunity to teach about the connection between emergent aquatic insects, contaminants and riparian areas. Our objectives were to 1) quantify abundance, diversity, and biomass of terrestrial and aquatic insects throughout the spring and summer using citizen scientists to collect data, 2) compare the data collected qualitatively by citizen scientists to researcher-collected quantitative invertebrate samples to determine if citizen scientists can collect representative samples 3) correlate riparian songbird mercury contamination with availability of emergent aquatic prey in the riparian zone, along with songbird diet assessed through fecal metabarcoding.
Results/Conclusions
Over 13 individual sampling days, citizen scientists collected 1832 individual aquatic invertebrates and 4021 terrestrial invertebrates. Their qualitative data collection (which was designed to allow a wide range of ages, experience and enthusiasm levels to participate) tracked the major seasonal changes in invertebrate diversity, as assessed through our paired quantitative sampling. While some citizen scientists did focus on certain large bodied invertebrates, we believe that the positive impact of including park visitors in data collection outweighs the negatives of their more biased samples. We additionally sampled 44 riparian songbirds for blood mercury and fecal invertebrate DNA. Mercury concentrations ranged from 0.029 ppm to 0.563 ppm (ww). Preliminary results show that sites with high insect emergences generally have higher Hg concentrations in riparian songbirds. Documenting, understanding, and protecting cross-ecosystem subsidies now is critical as we manage for resilient ecosystems in the second century of stewardship at Acadia.