The mesozooplankton of the Patos Lagoon Estuary, Brazil: trends in community structure and secondary production

Our study examines community structure and nymphal biology (life cycles and secondary production) of stoneflies in two adjacent mountain streams with different degree of forest cover in the Prosiečanka River Basin (Chočské Vrchy Mts., West Carpathians). One of the streams has non-forested catchment, converted to meadows and pastures, while the other one has catchment with 60% covered by spruce forest. Differences in forest cover and in thermal regime of the streams were reflected by the difference of stonefly communities at their structural and functional level. Species Nemoura cinerea and Leuctra aurita created stonefly assemblage in non-forested stream, whereas Nemoura cinerea also occurred in naturally forested stream together with species Leuctra armata, Leuctra nigra, Leuctra prima, Siphonoperla neglecta and Arcynopteryx dichroa. All examined species had maximally annual life cycle and in eudominant species Nemoura cinerea one month shift was found in nymphal hatching and adult emergence between streams. Total secondary production of stoneflies in undisturbed stream (126.46 mg DW m-2 y-1) was more than two times higher than the production in non-forested stream (47.39 mg DW m-2 y-1).

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Trophic quality of waters in the Patos Lagoon estuary: a comparison between its margins and the port channel located in Rio Grande, RS, Brazil

Acta Limnologica Brasiliensia ◽

10.1590/s2179-975x10716 ◽

2017 ◽

Vol 29 (0) ◽

Cited By ~ 4

Author(s):

Rafela Neves Marreto ◽

Maria da Graça Zepka Baumgarten ◽

Mônica Wallner-Kersanach

Keyword(s):

Water Flow ◽

Effluent Treatment ◽

Trophic State Index ◽

Patos Lagoon ◽

Nitrogenous Compounds ◽

Hydrological Conditions ◽

Quality Of Waters ◽

Patos Lagoon Estuary ◽

State Index

Abstract: Aim This study aimed to evaluate the Trophic State Index (TSI) at the margin and in the channel of the Patos Lagoon estuary, considering different hydrological conditions. Methods Surface and bottom water samples were collected in three sites in the channel (margin and center) and in two sites at the Saco da Mangueira in different hydrological conditions in 2011. Results Waters at the Saco da Mangueira are very contaminated by phosphate and nitrogenous compounds. The TSI classifies these waters as being hypereutrophic, the consequence of both the release of effluents which were poorly treated and the low water flow in the inlet. Contamination was mild at the margins of the channel, where waters were classified as being eutrophic and mesotrophic. Trophic balance (mesotrophic waters - oligotrophic surface - bottom) was found in the center of the channel as a consequence of strong water flow and dilution of contaminants coming from the margins. Conclusions Spatial variation in the TSI value enabled clear distinction to be observed between the areas at the margins and in the channel, because it reflected the punctual presence of anthropogenic input in the marginal waters, mainly in the Saco da Mangueira. Effluent treatment must be required in order to control severe trophic imbalance in the waters at the margins of the city. Variations of the proposed index are a useful tool to identify sources of phosphate compounds in other aquatic environments.

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