Oral Presentation Society for Freshwater Science 2025 Annual Meeting

Diatoms from the two Puerto Rican NEON stream sites with contrasting ecological integrity: Similarity and natural variability, species replacement, and contribution to ecosystem functioning (118406)

Marco Cantonati 1 2 , Don F. Charles 2 , Rosalina Christova 3 , María Cid Rodríguez 4 , Ionel Ciugulea 5 , Kalina Manoylov 6 , Daniel Spitale 7 , Flavia Tromboni 1 8
  1. Alma Mater Studiorum - University of Bologna - UniBO, Department of Biological, Geological and Environmental Sciences - BiGeA, -, Italy
  2. Academy of Natural Sciences, Drexel University, Philadelphia, PA, US
  3. Department of Environmental Science & Policy, George Mason University, Woodbridge, VA, US
  4. Department of Ecology and Animal Biology, University of Vigo, Vigo, Spain
  5. Algae Consulting Inc., -, TX, US
  6. -, Georgia College & State University , , Milledgeville, GA, US
  7. -, BMT Biomonitoring Team, Tre Ville (TN), Italy
  8. -, Rheinland-Pfälzische Technische Universität Kaiserslautern-Landau, Kaiserslautern, Germany

To contribute to a more thorough documentation and understanding of tropical freshwater diatoms, we studied 82 samples of epilithic diatoms, collected on 11 sam­pling dates in the different seasons from 2015 to 2016 from Rio Cupeyes and Rio Guilarte (southwest Puerto Rico) subjected to different degrees of anthropogenic impacts. On each sampling date, a primary (riffle) and, usually, a second­ary habitat (run in Cupeyes and pool in Guilarte) were sampled. The samples were  taken in the frame of the National Ecological Observatory Network (NEON). The detailed data on spatial (and temporal) natural variability will be discussed, in particular in relation to the similarity standards imposed to diatom-based assessments by quality control procedures. A clear species replacement in all the main diatom genera was noted in the two streams in relation to the impact of nutrient enrichment. We will also use available NEON data, such us PAR, dissolved oxygen, quantitative measures of periphyton etc. to start outlining the relevance of epilithic diatoms in overall stream metabolism and their contribution to ecosystem functioning. A more in depth understanding of the structure and function of diatom communities in tropical stream ecosystems is important  because they are highly vulnerable to changes in land use and vegetation in their catchments.