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Mussels of the Altamaha presentation by Glynn Environmental Coalition

Spiney Mussels

Rare Altamaha mussel proposed for endangered species listing
By Gail Krueger, ARK Communications Director and Jimmy Rickard, U.S.F.W

Casual visitors rarely see one of the most intriguing animals of the Altamaha watershed yet its presence—or absence—is an important indicator of the health of the river.

Spiney MolluskThe Altamaha spinymussel (Elliptio spinosa) is a type of pearly mussel found nowhere else except in the Altamaha. It's large—a full grown one would fill your hand--dark brown, shinny and has one to five distinctive spines on its upper and lower shells. If you see one, you won't mistake it for any other kind of mussel.

On June 13, the spinymussel was listed as a candidate for the endangered species list. But full federal protection is not expected anytime soon because many other candidate species must be evaluated first.

The Georgia Department of Natural Resources is also concerned about the unique mussel and is partnering with The Nature Conservancy to develop a species conservation agreement with private landholders and other interested parties. These types of agreements offer more flexibility for implementing conservation program and avoid some of the regulatory requirement for list species, said Mike Harris, chief of the DNR Wildlife & Natural Heritage Section.

The Altamaha spinymussel was described from the Altamaha near its mouth at Darien in 1836. It is found in stable, coarse to fine sandy sediments of sandbars and sloughs and is restricted to swiftly flowing water. It lives buried approximately 2 to 4 inches below the substrate surface.

Jimmy Rickard, a Fish and Wildlife biologist from Athens, says the spinymussel is in trouble.

He recently completed a report about its status. The Altamaha Riverkeeper organization provided much of the pollution case histories needed to support the effort to get the mussel listed.

The historical range of the spinymussel is restricted to the Coastal Plain portion of the Altamaha River, and the lower portions of its three major tributaries, the Oconee, Ocmulgee, and Ohoopee Rivers. Since its description, many collectors have sought the unique spinymussel—another factor that can contribute to its decline. It has no commercial value.

Recent searches for the mussel have revealed a dramatic decline in the number of populations and number of individuals throughout the species historical range.

In the Ocmulgee River, the spinymussel was known historically from its confluence with the Oconee River to an area about 35 miles upstream, near Jacksonville, Georgia.

There are few historical records of spinymussels from the Oconee River. However, the species has not been taken there since the late 1960's and is probably gone from the system.

Although spinymussels were found in the past two years in the Ocmulgee and Altamaha Rivers, the recent surveys reveal some disturbing trends, Rickard wrote.

First, there were no spinymussels found in the Ohoopee River. Second, most of the historical collection sites on the Ocmulgee and Altamaha rivers no longer have spinymussels. Further, the historical locations that still had spinymussels had significantly reduced populations. Fewer than 25 live mussels were found in over 250 person hours of searching throughout the historical range. This is in sharp contrast to historical collections where as many as 60 individuals were found in a single bed. Third, although juvenile mussels are generally difficult to find, historic surveys were successful at finding some juvenile spinymussels. Recent surveys utilized the same sampling techniques as previous surveys yet failed to find many juveniles. This indicates that little recruitment is occurring within the population,'' Rickard wrote.

It seems that the range and numbers of the Altamaha spinymussel have sharply dropped over the past 30 years. It may be gone altogether from the Ohoopee and Oconee Rivers and is struggling to survive in the Ocmulgee and the Altamaha.

So, what's happening to the spinnymussels?

No one knows for sure, but several things seem to be contributing to its decline including the degradation of its habitat due to a number of reasons, Rickard says. Improper wastewater discharge, sedimentation, contaminants, declining populations of potential host species, over withdrawal of surface water, low baseline flow of the rivers, and traffic from all terrain vehicles (ATV's) within the stream channels could all be contributing to the declining population of spinymussels.

Numerous municipal wastewater treatment plants discharge large quantities of effluent into the Altamaha River or its tributaries. The scale and cumulative effect of so many waste facilities may also be impacting the spinymussel, Rickard says.

For example Bibb County, Georgia, which includes the City of Macon, was permitted to discharge 39.70 MGD of domestic wastewater into the Ocmulgee River in 1990. The wastewater treatment discharge from Reidsville State Prison enters the Ohoopee River about six miles upstream of the largest historical population of spinymussels known from that river. ARK has reported fecal coliform discharges from there as being out of compliance with their NPDES permit.

The Altamaha Riverkeeper is monitoring as many of these wastewater facilities as possible.

The Oconee, Ocmulgee, and Ohoopee River systems contain significant acreage in cotton and onion farming. One of the most important pesticides used in cotton farming, malathion, is known to inhibit physiological activities of mussels that may decrease the ability of a mussel to respire and obtain food.

Another issue is Plant Hatch. While the current operation of Plant Hatch may degrade the habitat, the greatest concern for the spinymussel is the expansion of operations at Plant Hatch and the proposed dredging to expand the intake basin at the plant. That could destroy more mussel habitat.

Non-indigenous species such as the flathead catfish (Pylodictis olivaris) and the Asian clam (Corbicula fluminea) have been introduced to the Altamaha Basin and may be having an adverse effect on the spinymussel as well as other native species. Some native fish act as host for mussel larvae—fewer host fish mean fewer mussels And Asian clams may be out eating our native mussels.

The effects of water withdrawal combined with the drought have left the river with very low flow rates that may have a direct impact to the spinymussel. These problems are compounded by ATV usage and the resulting increased concentrations of contaminants. The prolonged drought has opened the riverbed for ATV and four-wheel drive access. Mussels that might have survived the drought are in danger of being directly crushed by heavy vehicular traffic in the riverbed itself. Additionally, the low flow rates that have resulted provide lower volumes of water to dilute potential contaminant and therefore, effectively increase the concentration of contaminants in the river.

Rickard and others concerned about the mussel ask that people report illegal dumping, pollution discharges and erosion problems to the Riverkeeper and appropriate agencies so the mussel can be better protected. He also ask the people maintain adequate stream buffers and discourage ATV rider from crossing streambeds.

Mussels of the Altamaha presentation by Glynn Environmental Coalition

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