Downeast Maine Rivers Chronically Low pH and High Organic Aluminum Experimental (Pilot) Clam Shell Addition Project Assessing shell degradation rates over a range of stream influences Discarded clam shells at shucking facility Free Calcium to increase stream pH! 5kg aliquots 3@ 5kg bags of clam shells Stream Variables: Water Temp pH Velocity High Velocity site Weighing bags

Sample Locations in Machias (7) and East Machias Rivers (1) * Inferred from Robinson et al. 2003

How “Big” are They? Dry Weight Density Kg/m3 ½ shell Composition; 88-92% CaCO3 Dry Weight Density How “Big” are They? Kg/m3 ½ shell

In Vitro Analysis Bucket with 387.4 g of shells- no flow! Ambient pH pH Just after Filling Bucket “pH” 24 hours after Filling Bucket? No Agitation End Weight 386.5 g 8.50 6.59 6.58

In Situ Methods Placed 5 (5 kg) bags of clam shells per stream Duration Sept 2nd through November 21st (80 days) Sampled weekly through Oct 21st Recorded -Visual Shell Loss -Insect Colonization (very few observed) -pH -Water Temp -Water Velocity Transformed Shell Loss data to “Normalize Distribution” Log (238+ g/day shell loss)

Log (238+ g/day shell loss) Omit these from further analysis Log (238+ g/day shell loss) Nominal Variables: 0 No visible loss 1 Small particle loss 2 Medium particle loss 3 Large particle loss

After removing all data where shell loss was observed Assessed Degradation with 3 Independent Nominal Variables Stream Velocity pH Time-Temperature

statistically significant Summary: Statisticians have not yet resolved the high degree of variability within the data set- The jury is still out on these interactions! Degradation ~22 g/day (0.5%/day) ~193 days to “Disappear” Although not statistically significant Stream Velocity, pH & Date-Temp may effect degradation rates

Air Temps and Discharge Old Stream USGS Gage 01021480

Maine DEP Sonde “pH” Data Data courtesy Mark Whiting