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Impacts of Seasonal Thermal Stress on Energetics of Popenaias popeii (Texas hornshell)




Pieper, Evelyn

Type of Degree

Master's Thesis


School of Fisheries, Aquaculture, and Aquatic Sciences

Restriction Status


Restriction Type

Auburn University Users

Date Available



Texas hornshell (Popenaias popeii) is a federally endangered mussel occurring in Texas, New Mexico, and Mexico. We examined temperature effects on energetic costs of feeding, and on scope for growth: the net energy balance available for reproduction and growth. Mussels were acclimated to experimental temperatures for ≥ 2 week and then subjected to energetic assays (i.e. respiration rate, clearance rate, and assimilation efficiency). Energetic costs of feeding and digestion were greatest at lowest (16℃) and highest (32℃) temperatures tested, but negligible at intermediate temperatures (20℃). Scope for growth peaked at 28℃ and rapidly fell as temperatures increased from 28 to 32℃. Riverine temperature profiles suggest that the primary growing season is in early summer and early fall, with declining surplus energy in mid-summer. Flow regulations to help minimize unfavorable temperatures during mid-summer may be critical for the long-term survival of this species.