The influence of hydrodynamics on the spatial and temporal variation of phytoplankton pigments in a large, sub-tropical coastal lake (Brazil)

Abstract

This study evaluated the spatial and temporal distribution of phytoplankton pigments in Itapeva Lake and its relationship with hydrodynamic aspects. Regarding spatial distribution, a decreasing N→S gradient was generally observed for the pigments, except in summer. This inversion observed during the summer was influenced by the predominant fetch (N-E). The horizontal heterogeneity was proved (

Environmental quality evaluation of lakes in the Rio Grande do Sul coastal plain

“…Predominant direction of winds in one yearly cycle, from October 1997 to September 1998, was as follows: 2.04% North, 43.46% Northeast, 8.53% East, 11.03% Southeast, 4.36% South, 10.66% Southwest, 6.39% West and 13.53% Northwest. The data revealed a predominance of northeasterly winds in the region a result supported by several authors (Würdig 1984, Hasenack and Ferraro, 1989, Tomazelli and Willwock, 1991, Tabajara 1994, Cardoso, 2001and Cardoso and Marques, 2004. Water temperature varied in accordance with a regional climate pattern (summer average: 27.O o C in January and winter average, 11.3 o C in July), repeating a similar temperature pattern at all sampling stations.…”

Hydrodynamic Control of Plankton Spatial and Temporal Heterogeneity in Subtropical Shallow Lakes

“…Lake Mangueira has been sampled for several years, although for the modeling exercise reported here we used data also collected at three fixed sampling stations (North, Center and South) from 2000 to 2001. The sampling protocol as well as some results were published previously by , 2004a, 2004b, 2004c for Itapeva Lake, and by Crossetti et al (2007) andFragoso Jr. et al (2008) for Lake Mangueira. Environmental data (air temperature, precipitation, wind velocity and wind direction) from the meteorological station (DAVIS, Weather Wizard III, Weather Link) installed at the Center point were recorded every 30 min (beginning 24 h before each sampling event) throughout the period.…”

“…Because of this rapid response, the plankton communities showed correspondingly rapid changes in composition and abundance, especially the phytoplankton when the resources (light and nutrients) responded promptly to wind action. This interaction between wind on a daily scale (hours) and the shape of Itapeva Lake was a determining factor for the observed fluctuations in the rates of change for phytoplankton as well as for the spatial distribution of plankton communities (Cardoso & Motta Marques, 2004a, 2004b, 2004c. The rate of change in the phytoplankton was very high, indicating the occurrence of intense, rapid environmental changes, mainly in spring.…”

“…In this chapter, we present the results of comparative modeling of two subtropical shallow lakes where the wind, and derived hydrodynamics, and river flow act as the main factors controlling plankton dynamics on temporal and spatial scales. The basic hypothesis is that wind and wind derived-hydrodynamics are the main factor determining the spatial and temporal distribution of plankton communities , 2004a, 2004b, 2004c, in association with point incoming river flows. The spatial heterogeneity of phytoplankton in Lake Mangueira is influenced by hydrodynamic patterns, and identifying zones with a higher potential for eutrophication and phytoplankton patchiness (Fragoso Jr. et al, 2008).…”

Limnological patterns in northern pantanal lagoons

“…Whatever it could be, the chlorophyll a concentration was higher than in other lagoons in Brazil. For example, the Itapeva Lagoon, a subtropical lagoon in the south of Brazil presented a mean concentration of 34.7 µg.L -1 chlorophyll a in the spring and a mean value of 7.7 µg.L -1 chlorophyll in the summer (Cardoso and Marques, 2004) and the Carapebus Lagoon in Rio de Janeiro which showed a mean concentration of 19.9 µg.L -1 at pollution-free points (Attayde and Bozelli, 1999). In addition, the lack of the connection of the lagoons with the river during the drought in the Northern Pantanal temporarily isolates the cycling processes.…”