3.1. Spatial distribution of salinity, temperature, and CDOM absorption coefficient Spatial distribution of mean salinity, temperature, and CDOM absorption coefficient along transect with station 1 being a marine water end member while station 15 being a freshwater end member is illustrated in Figure 3. It is characterized by surface mean salinity gradient, ranging from (12.04±4.23) psu to (7.18±5.73) psu in spring, (24.26±0.91) psu to (0.31±0.30) psu in summer, (23.81±2.47) psu to (5.35±0.92) psu in fall, and (23.75±5.86) psu to (6.87±5.09) psu in winter from station 1 to station 15, respectively (Table 1). Weak salinity gradient in spring indicated influence of fresh water from the north to the south while …show more content…
Seasonal variability in temperature, salinity and aCDOM-355 at station 1 and station 15.
Season Station-01 (South of Barataria Bay) Station-15 (North of Barataria Bay) Salinity
(°C) aCDOM-355 (m⁻¹) Salinity
(°C) aCDOM-355 (m⁻¹)
Spring 12.04±4.23 24.58±3.09 3.42±0.35 7.18±5.73 27.94±3.40 7.41±0.63
Summer 24.26±0.91 30.05±0.75 1.84±0.30 0.31±0.30 29.8 6.87±0.85
Fall 23.81±2.47 27.13±1.62 1.65±0.36 5.35±0.92 27.03±2.35 6.41±0.98
Winter 23.75±5.86 16.6±3.69 2.11±0.77 6.87±5.09 15.31±3.21 7.68±1.8
Figure 3. Spatial and seasonal distribution of mean salinity, temperature and CDOM absorption coefficient in Barataria Bay. Station 1 is marine end member while station-15 is freshwater end member. Seasonal variability is illustrated by different symbols with summer (filled circles), winter (open circles), spring (inverted triangles), and fall (open triangle).
2.2. Seasonal variability of aCDOM, slope, salinity and …show more content…
Lower bay includes station 1 to 5 and those are likely to be influenced by marine environment while station 11 to 15 are part of upper bay and those are mainly characterized by fresh water environment. The central bay contains station 6 to 10 and it has intermediate properties of both marine and fresh water end members. In the lower bay, the lowest salinity (13.3±4.2) psu observed in spring while it was relatively higher in winter (29.5±5.8) psu. The wide salinity range in lower bay is likely due to seasonal variability in river discharge, wind stress and tidal exchange between the bay and shelf waters. Similarly, high aCDOM-355 (4.2±1.1 m-1) was apparent in spring with approximately 55%, 75% and 68% higher values compare to summer, fall and winter, respectively and it reflects influence of MR water during high flow condition. The lower bay experienced high water temperatures (29.6±0.6 °C) in summer likely due to increased solar insolation, reduced river flow and intrusion of warm shelf water, whereas relatively low water temperature (16.4±3.6 °C) in winter indicated influence of strong winds corresponding to high-pressure system and decreased solar insolation. Small CDOM slope (S275-295) values indicated supply of fresh CDOM likely due to river flow in spring and wind forcing during winter while large