Water Resources Research Act Program

Details for Project ID 2020CT028B

Paleolimnology and molecular investigation to understand blooms of Didymosphenia hullii, Didymosphenia geminata, and Cymbella janischii; nuisance stalk-forming diatoms in the West Branch of the Farmington River, Connecticut, USA.

Institute: Connecticut
Year Established: 2020 Start Date: 2020-02-28 End Date: 2021-02-25
Total Federal Funds: $10,683 Total Non-Federal Funds: $33,519

Principal Investigators: Diba A. Khan-Bureau

Abstract: Diatoms are ubiquitous microscopic algae found wherever there is water, including in lotic or lentic ecosystems, the ocean and in moist sands. Diatoms form significant components of most aquatic ecosystems, especially as primary producers in rivers. In recent years and for reasons not fully understood, stalk-forming diatoms are believed to have expanded their global range. This expansion and other unknown processes have triggered prolific blooms with thick mats of long filamentous stalk material causing adverse conditions to river ecosystems worldwide. These conditions include the biological deterioration of habitats, loss of biodiversity and significant negative impacts on the sport fishing industry. Until recently, these nuisance diatom species have not posed problems for rivers in Connecticut. However, three especially problematic and nuisance stalk-forming species are now known to be actively growing in the West Branch of the Farmington River, in Connecticut. The first species, Cymbella janischii, is documented as regionally endemic in the Pacific Northwest. The second species, Didymosphenia hullii, was recently described from the West Branch of the Farmington River. The third recently confirmed species is Didymosphenia geminata. This taxon is globally distributed and has caused undesirable impacts to countless river ecosystems. The distribution of these problematic species, and the extent to which they could spread, poses a potential risk not only for the West Branch of the Farmington River, but other rivers in the state, which boasts an economic value of millions of dollars annually from fishing and fishing related activities. Didymosphenia taxa are known to grow abundantly in stable flowing, regulated, cold, oligotrophic waters, which are similar conditions to portions of the West Branch of the Farmington River where they grow today. During the drought summers of 2015–2017, these species expanded their range within the river. Preliminary data indicated changes in size and morphology of D. hullii, but this later was determined to be due to the presence of an additional species, D. geminata. Cymbella janischii grows more prolifically further downstream of the Didymosphenia taxa, in slightly warmer waters with higher levels of nutrients. However, all three taxa were found sporadically together. Will these diatoms continue to migrate to other rivers in Connecticut and the Northeast? This study will examine the three stalk-forming diatom phylogenetic relationships using DNA analyses, verify whether the three taxa historically have been present, but are rare or absent in the West Branch of the Farmington River, assess the expansion of their geographical range in the river and evaluate what environmental and anthropogenic factors triggers these diatoms to bloom. We will use core samples to examine presence or absence of these taxa. Core sampling has been used successfully to examine paleo-records of frustules from lakes, though hasn’t been frequently used in rivers because of limitations and challenges of flow and sedimentation. However, preliminary core samples may provide enough information to determine the historical presence or absence of these nuisance stalk-forming diatoms. The core samples can be archived for future lead-210 dating.