The International Mussel Watch 



1 .7. 10 Bivalve Sampling Position Log 



Under "Sampling Location", sections are provided for documentation of three types of 

 sampling techniques: subtidal use of fork, tongs or rake; subtidal dredge sampling and intertidal 

 sampling. If only one sampling location is applicable to the bivalves collected for the station(s) 

 referenced, the number 1 is entered on the line following "Sampling Location". If more than one 

 location is sampled for the station(s) referenced, additional Bivalve Sampling Position Logs should 

 be completed and numbered accordingly. 



1 .7. 1 1 Bivalve Observations Log 



Field observations and types of bivalve samples collected are recorded on the Bivalve 

 Observations Log. Where possible LORAN coordinates are preferable for site location recordings. 

 Otherwise, accurate long/lats records with compass bearings of prominent land marks will be 

 acceptable. 



Due to variation in propagating conditions, losses and irregularities over the signal path and 

 internal receiver conditions, LORAN position resolution and accuracy degrades with increasing 

 distance from transmitung stations. Distance from the transmitter generally affects LORAN 

 accuracies according to the following relationship. 



Distance from Transmitter LORAN Offset 



200 mi (370 km) 15- 90 m 



500 mi (975 km) 60 -210m 



750 mi (1390 km) 90 - 340 m 



1000 mi (1850 km) 150 -520 m 



Precision is greatly influenced by the quality, condition and calibration of the receiver. 

 LORAN-C generally provides precision repeatability of a recorded fix taken several times at a 

 known location within 15 - 91 m (Maloney, 1978). 



Positioning accuracy is ensured through the daily calibration or position offset 

 compensation of the LORAN receiver relative to charted landmarks of Coast Guard aids to 

 navigation. Corrected LORAN time differences and latitude/longitude conversions are to be 

 recorded at all site centers. 



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