Predicting episodic ammonium excretion by freshwater mussels via gape response and heart rate

Freshwater mussels are a viable option to detect real-time changes in water quality within aquatic ecosystems. Known as ecosystem engineers, freshwater mussels are constantly filtering particles and recycling nutrients in the benthic community. Therefore, identifying their physiological responses to alterations in water quality will enable mussels to not only serve as biomonitors but help model their impact on nitrogen cycle. This research focuses on identifying how mussel gape and heart rate respond to the addition of phytoplankton following a period of limited food availability. Immediately following phytoplankton addition, mussels show a decreased gape position linked with changes heart rate. As the gape returns to an open position, overlying ammonia concentrations increase showing an end of the metabolism process. As a result, pairing physiological changes with increased concentrations of phytoplankton, freshwater mussels' impact on ammonium concentrations can be accurately predicted. By inputting experimental excretion rates combined with variations in gape position, dynamic models will be simulate ammonium concentrations in the overlying water.