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Mussel and Sediment Survey Underway in the Big River, Missouri
Midwest Region, December 3, 2013
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Several members of the Region 3 Dive Team work in shallow water to delineate suitable freshwater mussel habitat on the Big River, Missouri.  Once the boundaries of these areas are defined, they are surveyed at a later time.
Several members of the Region 3 Dive Team work in shallow water to delineate suitable freshwater mussel habitat on the Big River, Missouri. Once the boundaries of these areas are defined, they are surveyed at a later time. - Photo Credit: Heather Garrison, USFWS
The federally endanged scaleshell filters water on the stream bottom on the Meramec River at a reference site outside of the Big River study area.  In Ozark streams, mussels require stable substrate that normally is composed of a mix of gravel and sand.
The federally endanged scaleshell filters water on the stream bottom on the Meramec River at a reference site outside of the Big River study area. In Ozark streams, mussels require stable substrate that normally is composed of a mix of gravel and sand. - Photo Credit: Andy Roberts, USFWS
Service Biologists sampling freshwater mussels at a sampling site on the Big River.  A square frame is placed on the stream bottom at 150 random locations per site.  At each location, the substrate is removed by hand from inside the frame to a depth of 10 cm, placed in the attached bag, brought to the surface, and sorted on a floating sieve to find mussels.  Mussels are then identified, measured, and returned to the stream.  This sampling method estimates the density of mussels living on the stream bottom.
Service Biologists sampling freshwater mussels at a sampling site on the Big River. A square frame is placed on the stream bottom at 150 random locations per site. At each location, the substrate is removed by hand from inside the frame to a depth of 10 cm, placed in the attached bag, brought to the surface, and sorted on a floating sieve to find mussels. Mussels are then identified, measured, and returned to the stream. This sampling method estimates the density of mussels living on the stream bottom. - Photo Credit: Andy Roberts, USFWS

Missouri Ecological Services and Fish and Wildlife Conservation offices are working together to study native freshwater mussel populations and how they might be affected by stream sediments contaminated with heavy metals from lead mining on the Big River in southeastern Missouri. In preparation for this task, we researched published literature and conducted interviews with preeminent mussel biologists to develop and implement the most statistically and scientifically defensible survey methodologies.

 

In the summer of 2013 we completed the first phase of the study, which is locating and delineating survey sites. To accomplish this task, we traveled over 68 miles of the river channel searching for suitable habitat and mussel beds. This represents the first time the river has been thoroughly explored to determine the full extent and distribution of suitable mussel habitat. In all, 76 sites were identified and evaluated as potential survey sites. Suitable habitat was found in 20 of these sites, and these areas were delineated for later sampling.

We now are currently working on the laborious process of returning to sites with suitable habitat to intensively survey mussel populations and collect habitat and sediment samples. To date, we have completed 16 sites. The remaining sites may be completed by early summer of 2014. The data from this study will help determine the effects of heavy metal contamination on aquatic resources and inform future restoration efforts of native mussel populations on the Big River.

Aside from the government shutdown in October, several compounding factors have made this second phase of the project challenging. Many of the sites are located in remote river reaches and the sampling is equipment-intensive including the need for SCUBA gear. Late summer brought dry conditions and low flow in the river. This required survey crews to drag boats laden with heavy sampling gear by hand through shallow reaches of the river while traveling several river miles to and from sites. The days were long given that a site takes between 6-10 hours to complete sampling and some sites take an hour or more to reach. However, this is a task our survey team tackled with an amazing amount of stamina and perseverance.


Contact Info: Andy Roberts, 573-876-1911, andy_roberts@fws.gov



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