photographing the river, conducting bathymetry and seismology studies,
and characterizing channel sediment changes. Within the
study area, the Penobscot River channel in both flowing and impounded reaches
is dominated by coarse sediment with a predominately sand matrix. This is in
striking contrast to fine-grained sediment storage noted in many impoundments. Click to learn more: Geological Survey work
Water Quality/Insect Diversity
The Penobscot Indian Nation Water Resources Program monitors aquatic benthic
macroinvertebrates from seven specific locations and characterize water quality conditions via water samples and measurements from 10 sites. Water quality parameters collected include dissolved oxygen, temperature, conductivity, BOD, bacteria, turbidity, secchi
transparency, total suspended solids, pH, chlorophyll, and total phosphorous.
Researchers collect samples throughout the system that are
used for stable isotope analysis to provide
information on nutrient cycling and feeding habits of the various
species at different places and times throughout the system. Stable isotope
studies are based on the idea that "you are what you eat" because isotope
signatures of consumers reflect the isotope values of their prey, which in turn
can be used to infer food chain level and habitat associations (in this case
marine vs. freshwater). Pre-dam removal data collected in 2009-2011 shows
strong isotopic distinctions between the freshwater and marine food webs.
SONAR systems are used to monitor fish presence, abundance and movements in rivers, estuaries, and oceans. Our goal is to measure and understand changes in fish populations before and after the Penobscot River Restoration Project. We have been developing a standardized approach for long-term SONAR monitoring, and collecting pre-restoration data that will be the baseline for comparison in subsequent years following restoration activities. When correlated with other data, it is hoped that hydroacoustics will provide accurate estimates not only of biomass, but also of fish species.
Riparian Zone and Wetlands
Researchers are collecting data on the recolonization of the riparian zone of the river with specific attention on native and invasive plants, as well as wetland characterization.
Atlantic salmon adults
and other species including river herring and American shad,
are being tracked as they move past dams on their upstream migration. PIT (Passive Integrated Transponder) technology allows fish to be tracked via loops of wire (antennas) tagged fish must swim through located near the entrances
and exits of fishways. This allows researchers to determine if a fish
entered a fishway, and, if so, if it was successful in passing upstream.
Atlantic salmon smolt, both hatchery and wild, are being tagged and tracked as they descend the river, passing over and through dams, to the Atlantic. Several years of
results indicate that in the Penobscot River, migrating salmon move more
quickly through areas without dams than those with dams. Survival is markedly
higher in river reaches without dams.
assessing habitat and spawning of two species of sturgeon (shortnosesturgeon
and Atlantic sturgeon) in the Penobscot River. The presence of reproductive
females and suitable spawning habitat in the upper river has been documented.
Reproductive females from the Penobscot River have been tracked moving to the
Kennebec River, potentially indicating a complex reproductive migration pattern. Click to learn more: spotlight on sturgeon
Researchers are electrofishing to provide detailed information on species, total fish biomass, and abundance. Pre-removal many diadromous species were restricted to tidal waters below Veazie Dam, although Atlantic salmon, sea lamprey, and American eel were observed upstream. These data indicate that the restoration of connectivity through dam removal will likely result in predictable shifts in fish assemblages.
Meet the Scientist!: Steve Coghlan describes the impact of dam removal on sea-run fish and his work investigating fish communities pre-dam removal.