TABLE 2.
Levels of indicator and pathogenic bacteria in water during the four sampling eventsa
| Indicator or pathogenic bacteria (detection method) | Sample location | Concnb |
|||
|---|---|---|---|---|---|
| Day 1 |
Day 2 |
||||
| Low tide, morning | High tide, afternoon | Low tide, afternoon | High tide, morning | ||
| Enterococci (MF) | a | 1 (1) | 2 (3) | <2 | 110 (12) |
| b | 3 (4) | 1 (1) | <2 | 77 (25) | |
| c | 3 (3) | 10 (6) | 8 (6) | 37 (10) | |
| Wet | 4 (6) | 4 (3) | 8 (11) | 8 (12) | |
| Dry | 152 (52) | 45 (87) | 1,088 (381) | 63 (51) | |
| Enterococci (chromogenic substrate) | a | <10 | <10 | <50 | 100 |
| b | 10 | 30 | <50 | 50 | |
| c | 31 | 40 | <50 | <50 | |
| Wet | 3 | 1 | 3 | 1 | |
| Dry | 39 | 6 | 1,006 | 34 | |
| Enterococci (qPCR) | a | 13 | 37 | 40 | 144 |
| b | 17 | 55 | 42 | 157 | |
| c | 18 | 48 | 36 | 128 | |
| Wet | 1,033 | 680 | 276 | 140 | |
| Dry | 1,383 | 22,100 | Inhibited | 74 | |
| E. coli (MF) | a | 2 | <2 | <2 | 218 |
| b | <2 | <2 | <2 | 147 | |
| c | <2 | 4 | <2 | 27 | |
| Wet | <5 | <5 | 2 (1)c | 2 | |
| Dry | <5 | <5 | 4 (1) | 29 (35) | |
| Fecal coliforms (MF) | a | 2 | <2 | <2 | 275 |
| b | 4 | 4 | 2 | 213 | |
| c | 4 | 22 | <2 | 107 | |
| Wet | <5 | 13 (21) | 3 (1) | 26 (40) | |
| Dry | 387 (165) | 26 (10) | 20 (12) | 1,421 | |
| Presumptive S. aureus (MF)c | a | <2 | 11 | 11 | 21 |
| b | <2 | <2 | <2 | 32 | |
| c | 2 | 4 | 12 | 12 | |
| Wet | 14 (6) | 24 (6) | 20 (7) | 13 (14) | |
| Dry | 188 | 31 (51) | 1,048 | 132 (14) | |
| C. perfringens (MF) | a | <2 | 2 | 2 | 4 |
| b | 8 | 6 | <2 | 13 | |
| c | <2 | 4 | <2 | 8 | |
| Wet | 7 (2) | 6 (2) | 6 (3) | 3 (2) | |
| Dry | 38 (19) | 64 (24) | 11 (3) | 44 (5) | |
Sample locations a, b, and c are water sample locations at different distances from the sampling transect, and the wet and dry locations are sand sample locations in and above the intertidal zone, respectively, as shown in Fig. 1. For water, three samples were obtained for each enterococcus method and one or two samples were obtained for the other indicator and pathogenic bacteria. For sand, 5 to 10 samples were obtained for enterococci, 2 to 5 samples were obtained for presumptive S. aureus and C. perfringens, and 3 or 4 samples were obtained for E. coli and fecal coliforms.
The values obtained by the MF, chromogenic substrate, and qPCR methods are expressed in CFU, MPN, and genome equivalents, respectively, per 100 ml for water and per gram for sand. The values for each type of sample were averaged to obtain the results reported. The numbers in parentheses are standard deviations.
None of the presumptive S. aureus results were confirmed. No organisms were determined to be cocci by Gram staining, and none of the organisms grew on sheep blood agar of ORSAB media.