ZEBRA MUSSEL BIOFOULING CONTROL IN COTTAGE

AND OTHER SMALL VOLUME WATER SYSTEMS

PART A: Gerald L. Mackie, University of Guelph

SOME FACTS ABOUT ZEBRA AND QUAGGA MUSSELS

PART B: Barb Crosbie, Aquatic Sciences Inc.

AN INVESTIGATION INTO THE ABILITY OF

SIX DIFFERENT PRODUCTS TO

PREVENT ZEBRA MUSSELS FROM

INFESTING A SMALL VOLUME WATER SYSTEM

PART C: Report by Steering Committee

A CONSUMERS GUIDE TO EVALUATING THE DEVICES TESTED

THE GEORGIAN BAY ASSOCIATION

19 Edgecombe Avenue

Toronto, Ontario M5N 2X1

www.georgianbay.ca

Partially funded by:

The Greater Bay Area (G.B.A.) Foundation

48 Lesmill Road

Don Mills, Ontario M3B 2T5

TABLE OF CONTENTS PARTS A, B, C

EXECUTIVE SUMMARY

PART A:

A COTTAGER'S GUIDE TO UNDERSTANDING THEIR LAKE

INTRODUCTION A-1

SOME FACTS ABOUT ZEBRA AND QUAGGA MUSSELS A-2

PART B

BACKGROUND B-1

INTRODUCTION B-3

STUDY SITE B-4

METHODS B-4

RESULTS B-11

DISCUSSION B-19

PART C

ZEBRA MUSSEL REMOVAL/ELIMINATION C-1

TURBIDITY AND SUSPENDED MATERIAL REMOVAL C-2

MAINTENANCE C-3

INSTALLATION, AVAILABILITY AND COST C-4

(note: not all sections are included in this summary document version - for the complete report, download the .pdf file version)

EXECUTIVE SUMMARY

Zebra mussels (Dreissena polymorpha) were first discovered in Lake St. Clair in 1988. Since that time the mussel has spread throughout North America and has now invaded all the Great Lakes and over 50 Ontario lakes and rivers within the Great Lakes drainage basin. In addition, the quagga mussel (Dreissena bugensis), first discovered in 1990 in Lake Ontario, has spread throughout Lake Erie and Lake Ontario, with a few sightings on the Mississippi River. The impact on industries drawing water from the Great Lakes was rapid, and caused shutdowns due to severe flow reductions as mussels attached to intake structures and the insides of pipelines. The potential spread of mussels to more inland lakes and their impact on cottage intakes, and other small volume intake structures, were predictable.

This report provides cottagers with information to help prevent zebra and quagga mussels from plugging their intake structures. The report is divided into two parts. Part A describes three differences between zebra and quagga mussels that are needed to recognize them, such as:

(i) unlike zebra mussels, quagga mussels have an ability to live and reproduce in deep parts of lakes, so that cottage intakes at all depths will be affected

(ii) the zebra mussel is much more colourful than the quagga mussel and has alternating yellow, brown, black and/or white stripes

(iii) the zebra mussel has a much flatter bottom surface than does the quagga mussel whose bottom is more typically clam-shaped.

Part A also provides information that explains why zebra mussels are a problem (e.g., they have unique life cycle and they adhere to surfaces using byssal threads) and their potential impact on recreational activities and the ecology of the lake. Most importantly, cottagers are shown how to determine if zebra and quagga mussels will be a problem. For example, the cottager need not worry about infestations if:

(i) the pH is <7.0

(ii) the calcium level is <10 mg/L

(iii) water temperature is >15^oC for fewer than 7 to 10 days.

Cottagers would be wise to take action if:

(i) the pH is > 8.0

(ii) the calcium level is >20 to 25 mg/L

(iii) if water temperature is >15 to 18^oC for more than 20 to 30 days.

In Part A, the cottagers are also given some simple control methods to try before selecting a control device. If a control device is needed, the cottagers are told how to select an appropriate device, when to begin the control program and how to know if the control program is working.

The second part of this report, Part B, describes the performance of six different zebra mussel control methods under rigorous test conditions. The ability of these products to remove zebra mussels from the water column, preventing settlement in the test system, was the key parameter used to measure performance. The products were tested over a four month period, with each system receiving approximately 400 000 L of water. The configuration of the experimental test systems was intended to mimic that found in a cottage intake system.

The products tested in this trial included five filters and one small-scale chlorination treatment. The cost of the product, the ease with which it was installed, the level of maintenance required and its availability to the consumer were considered here in the performance evaluation. Part C compares the performance of the six devices tested here. The zebra mussel removal efficiency ranged from 73% to 100%, except for one product that experienced mechanical difficulties for the entire duration of the test. The filter products effectively removed zebra mussels from the water column and prevented settlement (>95%) in the test systems. However, several of these products required a high level of maintenance throughout the experiment. Also, the high cost associated with a number of these products would deter many consumers. A few of these products were difficult to install and would require either a professional assistance or a local handyman. The chlorination treatment, although eff ective in removing zebra mussels, would also be associated with high residual chlorine that may negatively impact non-target biota.

Background on Who Was Involved (Page B 2)

In early 1997 the Georgian Bay Association (GBA) facilitated the assembly of scientists and other experts in the zebra mussel field. The purpose of this group was to offer independent advice on the best zebra mussel control products for the 5,000 families in the GBA, on the eastern and northern shores of Georgian Bay and adjacent lakes and water bodies. It was hoped that the generation of such information would prove to be very helpful to all cottagers in zebra mussel infested areas across Ontario and eastern North America.

All known North American control product manufacturers were contacted to submit products. The cost of the testing was funded by the participating manufacturers while the scientific technical review and publishing of the report was funded by the Greater Bay Area (G.B.A.) Foundation – a registered Canadian Charity (#895811066 RR0001) that funds research and educational projects in the Georgian Bay area.

The members of the Zebra Mussel Control Product Testing Group (ZMCPTG) were:

*Used as a resource by this group

The group developed a schedule for their work as follows:

PART C

A CONSUMER'S GUIDE TO

EVALUATING THE DEVICES TESTED

REPORT BY STEERING COMMITTEE

Submitted

February 26, 1999

PART C TABLE OF CONTENTS

1.0 ZEBRA MUSSEL REMOVAL/ELIMINATION C-1

2.0 TURBIDITY AND SUSPENDED MATERIAL REMOVAL C-2

3.0 MAINTENANCE C-3

4.0 INSTALLATION, AVAILABILITY AND COST C-4

A CONSUMER'S GUIDE TO

EVALUATING THE PRODUCTS TESTED

February 26, 1999

The following discussion, generated from the data provided on Table 1, is intended for the reader to use when evaluating which product would be best for their situation. Device #6 (Zebra 12000) can only be evaluated for price and availability from the results of the experiment since the cage that supports the mesh bag collapsed early on in the experiment.

1. ZEBRA MUSSEL REMOVAL/ELIMINATION

The products tested here were capable of removing 73 to 90% of the zebra mussel veligers suspended in the water column, except for device #3 (Z-Eliminator) whose mode of action was chlorination, not filtration. The removal or elimination of settled zebra mussel larvae was much higher, ranging from 97 to 100%. The densities of mussels settling in the system was much lower than the densities suspended in the water column, indicating that the most of the mussels entering the system were not surviving and colonizing (devices #1, #2, #4, #5). Since the larger larval and juvenile zebra mussels (the settled fraction) pose a higher risk to the water system, the ability of these products to reduce settlement to 0-3% of the original population suggests that all are effective in preventing zebra mussel infestations in most small volume water systems. All products performed well in these waters; however, it is important to note that in waters with extremely high densities (i.e., greater th an 50 000/m3) the products that allow zebra mussels to settle may not be sufficient. Even though removal efficiencies are quite high for these products, it is important to realize that only device #3 (Z-Eliminator) was capable of completely eliminating zebra mussels from the water system. Despite its efficiency in eliminating zebra mussels, the use of chlorine in a cottage situation should be approached with caution and the local Ministry of Natural Resources office should be contacted prior to purchasing this unit for use in Canadian waters.

    TURBIDITY AND SUSPENDED MATERIAL REMOVAL

The location where the products were tested had turbidity levels ranging from 3 NTU to over 10 NTU, which translates into approximately 26 to 48 mg/L of total suspended solids. The total suspended solids level at the test station is quite high when compared to waters associated with most cottage areas (2 to 30 mg/L). Therefore, these performance trials acted as a worst-case scenario and tested the ability of these products to remove zebra mussels while dealing with high levels of suspended solids. In addition, this experiment also indicated how well each product could act as a pre-filter to water purification units found in many cottages.

The maximum amount of suspended material that these products were capable of removing was calculated by subtracting the minimum suspended solids concentration in each product from the maximum suspended solids concentration found in the control. These values ranged from a low of zero for device #3 (Z-Eliminator) to a high of 65% for device #4 (Zebra 5000). Device #2 (Aquastand) was capable of removing 38% of the suspended solids, where device #1 (Zebra Mussel Filter Systems, Inc.) removed 58% and device #5 (Z-Banc) removed 53%. The amount of material removed was related to the pore size of the filters, or absence of filter in device #3 (Z-Eliminator), filters with smaller-sized removing more suspended material.

The importance of suspended solid removal to the cottager should be based on the suspended solids concentration present in the water body, the way they use the water (ingestion vs. cleaning) and the volume of water used per season. For water bodies with high concentrations of suspended material, a product that has a relatively large pore size (i.e., device #2, Aquastand) would be the best choice for zebra mussel removal. A smaller portion of the suspended solids will be removed; however, the majority of the zebra mussels will be prevented from entering the system and clogging would be infrequent. Alternatively, the chlorine injection system (device #3, Z-Eliminator) could be used to control zebra mussel populations without substantial changes in the suspended solids concentrations or flow rates. In typical cottage waters with low concentrations of suspended solids, any of the products tested would work effectively, however, device #4 (Zebra 5000) would offer the most benefit, in te rms of removing suspended material prior to a water purification system. Device #1 (Zebra Mussel Filter Systems, Inc.) and device #5 (Z-Banã ) would be effective at removing over half of the suspended solids in the water column while keeping zebra mussel densities extremely low, providing a balanced trade-off between zebra mussel control and suspended solids reduction.

    MAINTENANCE

The amount of effort involved in keeping each test system operational during the performance trials was determined. The units requiring filter changes, chemical addition or alternate maintenance during the experiment were recorded to provide the consumer with an indication of possible problems that they may encounter.

Device #1 (Zebra Mussel Filter Systems, Inc.) did not require any maintenance throughout the experiment, nor is annual maintenance or removal required, according to the manufacturer. This unit is designed to be installed once with maintenance or filter changes performed by an underwater diver. A re-built unit is offered, at a reduced cost (US $350), to the owner if and when the original filters become clogged.

Device #2 (Aquastand) did not require maintenance during this experiment; however, the bag on the unit was shaken by the divers at the mid-way point in the test as it became laden with sediment. The required maintenance for this product is to wash the mesh bag at the end of the year when the unit is removed from the water (or if water flow rates decrease dramatically at the tap).

Device #3 (Z-Eliminator) requires the 25 cm nipple to be removed at the end of the cottage season, or late fall, to inject the calcium hypochlorite and initiate the chlorination. Other than this annual activity, no other maintenance was required in this experiment.

Device #4 (Zebra 5000) had to be serviced on three occasions during the experiment. The filters had become clogged with suspended material and water flow had decreased significantly. In these waters, the ability of this product to remove a large proportion of the suspended material resulted in maintenance problems. The manufacturer recommends that the filters be replaced at the end of each summer, when the unit is removed from the water. However, the results of this study indicate that if this unit is used in turbid waters, the filters will need to be changed more frequently.

Device #5 (Z-Banã) required maintenance on a number of occasions throughout the experiment, however, many of these instances were due to the setup of the water supply system and not necessarily the performance of the filter. Due to the extensive setup that was required to operate this system (holding tank and back-flush tanks, operated by switches connected to the pump), and the limited power source at the test site, many delays and interruptions were encountered. It is reasonable to assume that in a cottage with an existing water system and reliable power supply, these problems may not occur. The only problem that related directly to the unit's ability to remove zebra mussels was when the filter clogged.

    INSTALLATION, AVAILABILITY AND COST

The degree of effort required to install each of these products has been rated, based on the experience of the ASI field crew (technicians and divers). Device #2 (Aquastand), Device #3 (Z-Eliminator) and Device #4 (Zebra 5000) were easy to install due to their small size and light weight. In a cottage situation, one person would easily deploy these products off a dock or from a boat. Device #1 (Zebra Mussel Filter Systems, Inc.) was more difficult to deploy due to its large size and cumbersome shape. More than one person would be needed to deploy this product from a boat or off a dock. Alternately, and ideally, a diver could be used to install this device. The last two products, device #5 (Z-Banã ) and device #6 (Zebra 12000), both required submersed electrical wiring to operate and would require an electrician. Also, the large size of device #6 and its associated weight made it dif ficult to put in place. A diver would be required to deploy both devices to preserve their integrity. These last two systems would require professional assistance.

Except for device #6 (Zebra 12000) all products are readily available in Canada and/or the United States. The units stated as available in the United States could also be purchased in Canada; however, the installation of the units would not be included in these prices (as is presently the case when purchased in the United States). The distribution of these products ranges greatly, however, all are available directly from the manufacturer.

There was a wide range in price for the units tested in this experiment. The prices are provided in Table 1, in Canadian dollars, unless otherwise noted. The cost of the unit is provided, along with the price of the associated consumables. The cost associated with the latter represents an annual operating cost. When evaluating the cost of the unit to determine which product is best suited for their situation, the consumer should evaluate all other factors first. Also, the cost of the associated consumables should be incorporated into the final price, especially where annual costs are encountered.

Table 1. The performance of each device with respect to zebra mussel removal, cost, suspended material, installation, maintenance and availability.

*US $350 - for rebuilt unit to replace original