Systematic Analysis of Hydrogeomorphic Influences on Native Freshwater Mussels

Science Center Objects

Conservation and Restoration of Native Freshwater Mussels

Over the past 50 years, about 20 native freshwater mussel species have been lost or greatly diminished from the Upper Mississippi River System and overall abundance of mussels has substantially declined in many portions of the river. While factors contributing to these declines are largely unknown, native mussels appear to be responsive to variation in hydrophysical and geomorphic features. Federal and state resource managers are interested in understanding the physical, hydraulic, and geomorphic factors that might drive the distribution and abundance of freshwater mussels. A better understanding of the geomorphic metrics that associate with dense and diverse mussel assemblages can guide the designs of future habitat rehabilitation enhancement projects to support and provide new and improved habitats for mussel assemblages.

Image of a diver sampling for mussels in the Navigation Pool 8 of the Upper Mississippi River

Image of a diver sampling for mussels in the Navigation Pool 8 of the Upper Mississippi River

(Credit: Teresa Newton, USGS-Upper Midwest Environmental Sciences Center. Public domain.)

The overall objective of this project is to identify geomorphic drivers that influence the distribution and abundance of native mussels. This information will help resource managers to understand what constitutes mussel habitat in large rivers and to evaluate the effects of management actions (e.g., habitat rehabilitation and enhancement projects, drawdowns) on this imperiled faunal group. The following three objectives will help to accomplish this:

  1. Estimate the distribution, abundance, diversity, and recruitment of native mussels in two navigation pools (Pools 8 and 13) of the Upper Mississippi River (UMR).
  2. Identify geomorphic gradients using physical habitat metrics across six navigation pools of the UMR.
  3. Assess if geomorphic indices are predictive of the distribution, abundance, diversity, and recruitment of native mussels across six pools in the UMR.

Objective 1. Using SCUBA divers, mussels were surveyed at about 250 systematically selected sites in each pool. These data provide information
on the number and types of species present, total and species-specific abundance, abundance of adults and juveniles, age, length, diversity, and evidence of recent recruitment (percent of population ≤ 5 y of age). Some preliminary data can be found in the table below.

Objective 1. Using SCUBA divers, mussels were surveyed at about 250 systematically selected sites in each pool. These data provi

(Public domain.)

Objectives 2 and 3. Using spatial analyses, we will explore a series a mussel response variables and a suite of geomorphic indices (see table below) to determine which indicators of geomorphic condition may have the most influence on mussel populations.

Objectives 2 and 3. Using spatial analyses, we will explore a series a mussel response variables and a suite of geomorphic indic

(Public domain.)