Spatio-temporal spawning and larval dynamics of a zebra mussel (Dreissena polymorpha) population in a North Texas Reservoir: implications for invasions in the southern United States

Christopher John Churchill

doi:10.3391/ai.2013.8.4.03

Abstract

long-term monitoring program were analyzed to determine if spatio-temporal zebra mussel spawning and larval dynamics were related to physicochemical water properties in Lake Texoma. Reproductive output of the local population was significantly related to water temperature and lake elevation. Estimated mean date of first spawn in Lake Texoma was approximately 1.5 months earlier and peak veliger densities were observed two months earlier than in Lake Erie. Annual maximum veliger density declined significantly during the study period (p < 0.0001). A population crash occurred as a result of thermal stress and variability of lake elevation. In summer 2011, water temperatures peaked at 34.3°C and lake elevation declined to the lowest level recorded during the previous 18 years, which resulted in desiccation of substantial numbers of settled mussels in littoral zones. Veliger spatial distributions were associated with physicochemical stratification characteristics. Veligers were observed in the deepest oxygenated water after lake stratification, which occurred in late spring. Results of this study indicate environmental conditions can influence variability of population sizes and spatial distributions of zebra mussels along the current southern frontier of their geographic range. Although the future population size trajectory and geographic range are uncertain, increased temperatures and intermittent, extreme droughts likely will affect spatio-temporal dynamics of established populations if zebra mussels spread farther into the southern and southwestern United States.

Highlights

Less than two decades after introduction into North America, zebra mussels (Dreissena polymorpha [Pallas, 1771]) achieved rapid transcontinental spread (Strayer 2009)
Results from the current study indicate water temperature, lake level variability, and physicochemical stratification regime influence variability of population sizes and spatial distributions of zebra mussels found near the current southern frontier of their geographic range west of Louisiana
Continued monitoring in Lake Texoma will determine if the zebra mussel population follows a stable cycle trajectory and recovers to pre-crash levels, stabilizes at reduced densities, follows a chaotic, unpredictable pattern, or if the population crash results in local extirpation

Summary

Introduction

Less than two decades after introduction into North America, zebra mussels (Dreissena polymorpha [Pallas, 1771]) achieved rapid transcontinental spread (Strayer 2009). Incipient detection of zebra mussel adults in Texas was in April 2009 in Lake Texoma, a reservoir in the Red River Basin along the Texas-Oklahoma border (Texas Parks and Wildlife Department 2009). In July 2012, zebra mussels were detected in Ray. Roberts Lake, a reservoir in the Trinity River basin near the Dallas-Fort Worth metropolitan area (Texas Parks and Wildlife Department 2012). Roberts Lake, a reservoir in the Trinity River basin near the Dallas-Fort Worth metropolitan area (Texas Parks and Wildlife Department 2012) In June 2013, zebra mussels were detected in a third reservoir in north Texas, Lake Lewisville (Texas Parks and Wildlife Department 2013a). In September 2013, an established population was detected in Belton Lake near Temple, Texas (Texas Parks and Wildlife Department 2013b)

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Discussion

Conclusion