In the latter part of 1989, the Marine Biological Laboratory located at Horseshoe Cove switched from manual sampling to an automated meteorological and oceanographic monitoring system. Installed at the same site, this system records temperature and salinity at the aquarium's water system intake located in a deep rocky channel on the northern headland of the cove. The manual and automated data sets overlapped in 1990 with good agreement, so the manual collections of samples subsequently ceased in 1991. The temperature and salinity values presented are, for the most part, the 0815 data point, and since the water is deep and the headland steep and rocky, these values are representative of the coastal water.