The microbial quality of a marine tidal pool on South Africa's Atlantic coast was found to be inferior to that of the adjoining seawater (the latter complying with various water quality guidelines, the tidal pool failing). This seems to be due to pollution from the bathers using the pool.
Research Article|March 01 1995
Microbial quality of a marine tidal pool
Water Sci Technol (1995) 31 (5-6): 299-302.