Oral Presentation Society for Freshwater Science 2025 Annual Meeting

Biodiversity Recovery in Restored Streams: The Promise of Human-Assisted Translocation. (118626)

Ibrahim R Fagbohun 1 , Daniel Allen 1 , Jon Sweetman 1
  1. Pennsylvania State University, State College, PENNSYLVANIA, United States

Stream restoration has attracted multi-billion-dollar investments from federal and state agencies in the United States over the past three decades. While this huge investment has resulted in positive improvements in the physicochemical and hydrologic conditions of urban streams, biological recovery has in some cases, lagged. One cause could be the inability of organisms from suitable source populations to disperse to restored streams and become established, either due to distance or limited dispersal ability of freshwater fauna, especially macroinvertebrates. “Human-assisted translocation” of macroinvertebrates could improve biodiversity in restored streams by bridging the gap between source population and restored streams. However, we do not know if taxa from a pristine source population would survive at a restored stream site. We thus tested the survivability of translocated benthic macroinvertebrates using six streams in the Baltimore, Maryland area of the Chesapeake Bay. Three pristine reference streams were selected as the donor sites while three restored streams with depleted benthic macroinvertebrate diversity were selected as recipient streams. In each of the donor streams, 10 pairs of macroinvertebrate cages containing rock or leaf substrates were installed in the streambed for macroinvertebrate colonization. After four weeks, five pairs of the macroinvertebrate cages were randomly selected, removed, and sampled – while the other five pairs were removed and transported to the paired recipient stream for transplantation. To assess survivability potential, the macroinvertebrate cages were placed in mesh bags and left in the stream for four weeks, after which they were removed and sampled. This experiment was conducted in both Fall 2024 and Spring 2025. We will present the results from the Fall 2024 experiment and assess whether they suggest larger translocation efforts could be effective for achieving the required biodiversity uplift in restored streams.