Date of Completion

2016

Document Type

Honors College Thesis

Department

Biology

Type of Thesis

Honors College, College of Arts and Science Honors

First Advisor

Brent Lockwood

Keywords

zebra mussels, thermal tolerance, filtration rate, climate change, Lake Champlain

Abstract

Zebra mussels (Dreissena polymorpha) are an invasive and widespread species in North America, where they have large ecological and economic impacts. In the context of global climate change, it is uncertain how higher temperatures will affect the invasive success of zebra mussels. I tested the effects of acclimation temperature on thermal tolerance and filtration (i.e. feeding) rates of zebra mussels in Lake Champlain to shed light on the future success of this species in the lake and offer potential insight on how lake ecology may be affected with continued climate warming. Mussels were acclimated to four temperatures (10, 15, 22, 30°C) for a period of 1.5 weeks. Following this acclimation treatment, filtration rate was measured via absorbance spectrophotometry. Acute heat tolerance was scored by assaying mussel mortality during a heat ramp, in which temperature was increased at a rate of 0.15°C/min for 2.5 hours. I found no significant effect of acclimation temperature on filtration rate, although there was a trend in which filtration rate increased with temperature until 22°C after which filtration rate declined. Acclimation temperature did significantly affect survival after an acute heat shock event. The acute lethal temperature at which 50% of the mussels died (LT50) was approximately 37°C, and acclimation to 30°C led to an increase in LT50 of 0.65°C. My results indicate that zebra mussels have a heat tolerance that far exceeds the warmest temperatures likely to be experienced in Lake Champlain and therefore will successfully survive warming waters induced by climate change. However, increased temperatures do cause a decline in filtration rate, which may affect zebra mussel growth and reproductive capabilities and change the way they impact phytoplankton community composition and nutrient availabilities potentially exacerbating harmful cyanobacteria blooms, which are projected to occur with increasing frequency. These results offer insight on the response of Lake Champlain zebra mussels to thermal stress and the potential consequences to lake ecology due to climate change.

Creative Commons License

Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 License.

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