Habitat Suitability Parameters for Invasive Mussels at Reclamation Managed Facilities and Waters

Project ID: 6714
Principal Investigator: Sherri Pucherelli
Research Topic: Invasive Species
Priority Area Assignments: 2013 (Zebra and Quagga Mussels), 2014 (Zebra and Quagga Mussels), 2015 (Zebra and Quagga Mussels)
Funded Fiscal Years: 2013, 2014 and 2015
Keywords: invasive mussels, water quality, habitat suitability, potential for infestation

Research Question

Reclamation is currently challenged with management of invasive mussel infestations and many facilities throughout the West. Challenges also exist for managers of facilities in areas where mussel infestations have not yet occurred in preventing and/or preparing for mussel establishment. The suitability of specific water bodies for invasive mussel infestation and the population density that it could support can be an important factor for these managers in prioritization, budgeting, and decision making processes. Published water quality parameters related to the proliferation of invasive mussels have proven to be inaccurate in the Western U.S. in several instances (i.e. highly infested water bodies with water quality features outside of the published parameters). Dense infestations of mussels occur at every major reservoir along the Lower Colorado River. However, similar infestations downriver of Parker Dam have not been reported. A recent visit to Senator Wash noted several adult mussels attached to substrates, but nowhere near the population densities seen at Lake Mead, Mojave, or Havasu (~1 mussel per 3 square meters vs. ~20,000 mussels per square meter). Similar low-density infestations have been noted in the Central Arizona Project. Recent sampling efforts have confirmed the presence of numerous larval mussels in the water column of the Lower Colorado River as far south as Senators Wash, but for some reason they are not establishing dense colonies such as seen upriver of Parker Dam.

The research questions for this project are:

A) What factors downstream of Parker Dam are prohibiting large-scale and dense infestations of mussels?

B) What are the implications of these factors to other Reclamation water bodies in terms of their suitability for mussel infestations, as well as the level of infestation they could support?

C) Can manipulation of suitability parameters be used to prevent settlement in small-scale systems at Reclamation facilities

Need and Benefit

The majority of the body of literature that describes out current understanding of the water quality parameters associated with dreissenid mussel habitat suitability is related to studies and distributional records of zebra mussels. However, quagga mussels are the dominant species infesting Western water bodies, and there is evidence that this species has different tolerances for certain environmental conditions than zebra mussels. In addition, the relatively sparse information specific to quagga mussels has some uncertainty due to detections of mussels in water bodies with water quality characteristics outside of the published parameters. As an example, the literature suggests that adult quagga mussels cannot survive at calcium levels (considered the most critical variable for Dreissenid survival and population density) below 10 mg/L, and there is little potential for larval development at 10-12 mg/L. However, quagga veligers have been found in three Colorado waters with calcium below these thresholds (3.5-11 mg/L Ca). While veliger detections in these water bodies are not necessarily indicators of a sustainable adult population, they do emphasize the notion that the current understanding of water quality parameters associated with invasive mussel habitat is limited or that local adaptations may be occurring.

Accurate information regarding the level of suitability for water bodies to support invasive mussel populations is highly useful to Reclamation managers in preparing for and preventing or minimizing the potential for infestation. Certainty in the knowledge of suitability levels would allow prioritization of budget allocation and decision processes for water bodies that are at high risk for problematic infestations.

In addition, an accurate understanding of habitat suitability could be used as a management tool in small-scale systems (e.g. cooling lines of hydropower generators). Water quality parameters could be artificially altered to be outside of the acceptable limits within these systems to prevent mussel settlement with minimal environmental impacts. Studies regarding manipulation of pH have shown some promise in this area, and this study may reveal other potential variables that could be used as management tools.

Contributing Partners

None

Research Products

Bureau of Reclamation Review

The following documents were reviewed by experts in fields relating to this project's study and findings. The results were determined to be achieved using valid means.

Habitat Suitability Parameters for Quagga Mussels in the Lower Colorado River System and at Reclamation Managed Facilities (final, PDF, 2.7MB)
By Sherri Pucherelli
Publication completed on September 30, 2015

Large populations of invasive dreissenid mussels can cause biofouling issues that are of specific concern to Reclamation facility managers. Accurate information regarding the level of suitability of Western water bodies to support invasive mussel populations is highly useful to Reclamation managers in preparing for and preventing or minimizing the potential for infestation. Dense infestations of mussels occur at every major reservoir along the lower Colorado River. However, similar infestations downriver of Parker Dam have not been reported. The objectives of this project were to investigate what factors downstream of Parker Dam are prohibiting large-scale and dense infestations of mussels. The results of this study indicate that increased temperature and total suspended solids (turbidity) at downstream sites are likely contributing to reduced mussel settlement and survival. Conductivity also increases at Southern sites, and experiments conducted at Davis Dam indicate that increased conductivity levels similar to those observed at Imperial Dam can lead to a slight decrease in settlement. Additional findings indicate that nutrient parameters may not be predictive of veliger survival and abundance in river systems. Utilizing one or a few parameters for habitat suitability predictions may not provide a clear understanding of waterbody suitability for mussel colonization. Therefore a complete assessment of site specific water quality, hydrology and geology will hopefully provide a better determination of risk.
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Last Updated: June 29, 2015