(General Oceanics). These samples were used to determine the pH
of the water, dissolved oxygen and nutrient concentrations, and
thermotolerant coliform levels. Thermotolerant coliforms werealso
analyzed in samples of water collected from the Sonrisal stream on
Colares beach.
In the laboratory, dissolved oxygen was determined by the
Winkler method, as modified by Strickland and Parsons (1968) and
pH was measured using a pHmeter (Hanna HI 2221). Thermoto-
lerant coliform levels were determined using the method of the
American Public Health Association (APHA) (2012). The water
samples were vacuum-filtered through glass-fiber filters (Millipore
GF/F 0.7 m m, 47 mm), and then freeze-dried for dissolved nutrient
analyses. Dissolved inorganic nutrient (nitrite e NO 2 and nitrate e
NO 3 ) concentrations were determined by spectrophotometry,
following the procedures described by Strickland and Parsons
(1977) and Grasshoff, Emrhardt, and Kremling (1983). Filtered
water samples were also frozen for the subsequent analysis of
dissolved total phosphorus (TP) by applying an adaptation of the
simultaneous oxidation of nitrogen and phosphorus compounds
using an alkaline persulfate oxidizing solution (Grasshoff,
Kremling, & Ehrdardt, 1999).
5. Recreational carrying capacity of