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Note: Session titles beginning with an asterisk (*) have student presenters.
AUTHORS: Wendell Haag, US Forest Service, Southern Research Station; Monte McGregor, Kentucky Department of Fish and Wildlife Resources; and Jacob Culp, Kentucky Division of Water
ABSTRACT: Mussels have disappeared from many streams that lack obvious, point-source impacts. These disappearances indicate substantial ecosystem impairment, but the sources of this impairment are poorly known. Advances in mussel culturing methods make available large numbers of juvenile mussels that can be used as direct indicators of stream conditions. We conducted a series of field experiments using in situ exposures of laboratory-reared juvenile mussels to assess potential sources of stream impairment and mechanisms of mussel declines. Experiments involved placing juvenile mussels in flow-through chambers (silos) in streams for 3-4 months and monitoring their survival and growth. Survival was high in all streams, indicating a lack of acute toxicity. However, mussels did not grow in streams that have previously lost their mussel faunas. Mussels grew well in streams that continue to support mussels, but growth was variable according to natural watershed characteristics such as alkalinity, temperature, and productivity. Low growth was associated with human-influenced factors including nitrates/nitrites and pesticides. Low growth was also associated with streams with extensive karst influence, suggesting that groundwater pollution may be an additional factor. Mussel food sources did not differ consistently among low-growth and high-growth streams, but low-growth mussels showed a characteristic metabolic profile indicative of starvation. These results show that growth inhibition may be a mechanism for mussel declines, and associations with water quality variables suggest potential causes. In situ exposures with juvenile mussels offer a powerful and easily implemented approach for natural resource managers to assess stream conditions and sources of impairment.
Wednesday November 1, 2017 10:40am - 11:00am EDT
Breathitt