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Two field experiments were carried out using a custom built flow-through laboratory to test the effect of elevated pH on dreissenid musselsas a potential control method. Both experiments tested the ability of dreissenid pediveligers to settle under conditions of elevated pH and thelong-term survival of adult dreissenids under the same conditions. The two experimental sites had different water quality and differentspecies of dreissenids present. The settlement of quagga mussel pediveligers at the lower Colorado River was inhibited with increasing pH.At the maximum achieved pH of 9.1, there was approximately 90% reduction compared to the maximum settlement observed in the controls.Since the settlement was almost as low in pH 8.9 as at pH 9.1, the inhibition in settlement may have been due to the presence of a precipitateformed under high pH conditions rather than the increase in background pH. No mortality of quagga mussel adults was observed in theexperimental pH levels at the lower Colorado River. At San Justo Reservoir, zebra mussel settlement decreased with increasing pH. Newsettlement was almost entirely absent at the highest pH tested (pH 9.6). The observed mortality of adult zebra mussels was low, but did tendto increase with increasing pH. We also tested the response of adult zebra mussels to short-term exposure to very high pH levels (i.e. pH 10,11, and 12). Adult mussels in poor physical condition experienced 90% mortality after 12 hours at pH 12. For unstressed adult zebra mussels,90% mortality was reached after 120 hours at pH 12. Significant mortalities were also observed both at pH 10 and pH 11. From this study,we conclude that pH elevation could be used both as a preventative treatment to eliminate settlement by dreissenid mussels and as an end ofseason treatment to eliminate adults. The high pH treatment would have to be tailored to the site water quality to prevent formation ofprecipitate during treatment and to minimize corrosive action on materials of construction

Allometric relationships between calcified structures and total length of round goby Neogobius melanostomus were determined from a sample of fish ranging in total length from 53 to 152 mm. Each of the 10 allometric equations gave coefficients of determination (r2) that were greater than 0.80 and highly significant. The equations with the most predictive ability were those relating total length to cleithral, opercular, mouth, and pharyngeal bone measurements. Round goby remains were found in the stomachs of 10 predator species from the Bay of Quinte, Lake Ontario. Round goby were ingested most often by yellow perch Perca flavescens (40% of the stomachs examined) and largemouth bass Micropterus salmoides (27%) and less frequently by other predators. Round goby calcified structures most frequently found in the stomachs of predators were mouth parts (premaxilla and dentary), pharyngeal bones (dentigerous plate and pharyngobranchial plates), and otoliths. The predictive equations, diagnostic features of calcified structures, and list of predatory species in this study may serve as helpful tools for future analyses of round goby predator diets.