INTRODUCTION

Oak Orchard Creek is a major stream located in Orleans County, discharging into Lake Ontario at the town of Waterport, NY at Point Breeze.  As with other streams such as Sandy Creek, Genesee River, and the Oswego River, all have extensive marine traffic and commercial activities.  Oak Orchard Creek has over 300 private boat moorings along its banks extending from the Rt. 18 bridge and progressing north to its final discharge into Lake Ontario a total distance of 2.5 km.  Also located on this creek are three major marine commercial activities that deal with service and storage of these boats during the summer and winter months. 

These boats, for the vast majority, have had coatings applied to the under water parts of the hull.  These coatings are referred to as anti-fouling paint, or bottom paint.  These types of paints contain copper or tributyltin (TBT) as a biocide to retard or eliminate marine growth on the underside hulls of these vessels.

Growth of marine organisms on the hulls of ships causes increased drag, reducing ship speed and increasing fuel bills.  Shipís hulls are usually painted with specially designed paints containing toxic compounds that prevent the growth of these fouling organisms.  Anti-fouling paints rely predominantly on combinations of copper and TBT to control marine fouling.  TBT is considered the most effective anti-fouling to date; the lifespan of these anti-foul ants is seven years for TBT, in comparison with two to three years for copper-based paints.  On leaching from anti-fouling paints, TBT and copper are directly available in the water column. (Boat Tech )

TBT and copper affects marine organisms by interfering with biological functions such as growth, development, reproduction and immune response by acting on cell metabolism and causing malformations of the mitochondrial membranes.  Anti-fouling contaminants are non-specific and are toxic above threshold concentrations to many non-target marine organisms. (Birge, 1979) 

TBT and copper are moderately hydrophobic and after entering the aquatic environment are rapidly absorbed onto suspended particulate matter, sediments and sea grass.  TBT and copper are moderately persistent in sediment, with a half-life of months to years, being longer under anaerobic conditions.  Bioturbation, dredging, storms, anchors, and boat movement can all mobilize sediments and release anti-fouling contaminants back into the water column.

BACKGROUND

             Copper, or cuprous oxide, keeps marine flora and fauna from growing on the bottom of your boat.  Toxicants such as copper are the key to the effectiveness of these types of anti-fouling paints.  Not all anti-fouling paints are the same.  They contain different amounts of copper, have different ways of releasing the copper, and have different binders or the primary matrix in which the copper is held.  All copper based paints are usually released by a method called free association.  The biocide leaches freely from the matrix, and the initial release is rapid and uncontrolled.  As a result, boats that are just docked in a stream or river, are releasing the biocide.  Also, stream current or tides greatly enhance the release of the copper. 

            One difference in anti-fouling paints is the amount of copper the paint contains.  The secret to copperís effectiveness is how fast itís released.  The same holds true for TBT based anti-fouling paint.  This type of paint is released by a process called self polishing copolymer system.  The TBT is chemically bound within the matrix, and wears as the vessel is in motion.  This type of paint is currently used on all commercial vessels, and since these vessels operate in harbors with adequate tide flow, the paint is affective when the ship is moored. (ORTEP, 2001)

            The problem exists therefore, that these biocides are being released and being deposited in channel and harbor bottom sediments.  Commercial, as well as private marine facilities that are responsible for maintenance and hull preservation, routinely clean and repaint ships hulls.  This is done not only as a preservation step to reduce corrosion, but to remove any fauna or flora that would increase drag and reduce fuel consumption.  In the past, commercial dry docks would hydro blast, sandblast, and repaint the vessels and then wash the residual into the harbor.  This same practice is also conducted at all private marinas where pleasure boats are maintained and stored.  Oak Orchard Creek has three such marinas located on its banks.  Each year, several hundred boats are hauled out in the fall, washed down, and put up for storage.  The process of hydro blasting is done in close proximity to the launch ramps and runoff as a result of the washing flows into the creek. 

            TBT along with copper, exert an unusual toxicity both acute and chronic to marine life, especially shellfish.  Chronic effects including serious developmental and reproductive abnormalities have been documented.  Also, high concentrations of copper have affects on clam tissues and have impaired shell growth.  Copper also affects reproduction processes in most aquatic organisms.  Predator and prey recognition have also been documented.  Each species however, have different tolerances for both copper and TBT.  The fact remains, that copper, a biocide, is being introduced into the water at Oak Orchard Creek by present marine practices.  This introduction of copper therefore, must be becoming part of the bottom sediment at Oak Orchard Creek and an initial part of the food web.  Samples were taken along Oak Orchard Creek that were subject to bottom paint leeching and commercial injection.  (Birge, 1979)