Gilberto Fonseca Barroso

The morphometry of Lake Palmas, a deep natural lake in Brazil.

Lake Palmas (A = 10.3km2) is located in the Lower Doce River Valley (LDRV), on the southeastern coast of Brazil. The Lake District of the LDRV includes 90 lakes, whose basic geomorphology is associated with the alluvial valleys of the Barreiras Formation (Cenozoic, Neogene) and with the Holocene coastal plain. This study aimed to investigate the relationship of morphometry and thermal pattern of a LDRV deep lake, Lake Palmas. A bathymetric survey carried out in 2011 and the analysis of hydrographic and wind data with a geographic information system allowed the calculation of several metrics of lake morphometry. The vertical profiling of physical and chemical variables in the water column during the wet/warm and dry/mild cold seasons of 2011 to 2013 has furnished a better understanding of the influence of the lake morphometry on its structure and function. The overdeepened basin has a subrectangular elongated shape and is aligned in a NW-SE direction in an alluvial valley with a maximum depth (Zmax) of 50.7m, a volume of 2.2×108 m3 (0.22km3) and a mean depth (Zmv) of 21.4m. These metrics suggest Lake Palmas as the deepest natural lake in Brazil. Water column profiling has indicated strong physical and chemical stratification during the wet/warm season, with a hypoxic/anoxic layer occupying one-half of the lake volume. The warm monomictic pattern of Lake Palmas, which is in an accordance to deep tropical lakes, is determined by water column mixing during the dry and mild cold season, especially under the influence of a high effective fetch associated with the incidence of cold fronts. Lake Palmas has a very long theoretical retention time, with a mean of 19.4 years. The changes observed in the hydrological flows of the tributary rivers may disturb the ecological resilience of Lake Palmas.

Integrated Ecosystem Management of River Basins and the Coastal Zone in Brazil

International society has begun to consider river basins and the coastal zone as one management unit that requires an ecosystem approach. Various countries have undertaken initiatives since the 1970s and have improved the approach to integrated coastal zone management. Brazil has not been one of them. Its sector-based approach to most environmental issues started in the 1980s with the National Environmental Policy Act (Law 6,938/1981). The National Coastal Zone Management Plan (NCZMP) was then approved by Law 7,661 in 1988. Shortly thereafter, the 1988 Brazilian Constitution was enacted, which established the environment as a common good to be used by the entire society but in such a way as to prevent environmental degradation and conserve its quality for present and future generations. The National Water Resources Policy (NWRP) was not enacted until 1997 (Law 9,433/1997). This law established that water resource management in Brazil must take into account estuarine ecosystems and the coastal zone, using an integrated approach. Only in 2006 did the National Water Resources Council (NWRC) create a technical chamber dedicated to developing regulatory measures for integrated management in Brazil. There has been substantial discussion and various proposals to implement it, as outlined in this article. This paper concludes with suggestions for implementing integrated river basin and coastal zone management in Brazil.

Morphometry and mixing regime of a tropical lake: Lake Nova (Southeastern Brazil)

Lake Nova (15.5 km2) is the second largest lake in the Lower Doce River Valley (Southeastern Brazil). A better understanding of ecosystem structure and functioning requires knowledge about lake morphometry, given that lake basin form influences water column stratification. The present study aims to contribute to the understanding of relationship between morphometry and mixing patterns of deep tropical lakes in Brazil. Water column profiles of temperature and dissolved oxygen were taken on four sampling sites along the lake major axis during 2011, 2012 and 2013. The bathymetric survey was carried out in July 2011, along 131.7 km of hydrographic tracks yield 51,692 depth points. Morphometric features of lake size and form factors describe the relative deep subrectangular elongated basin with maximum length of 15.7 km, shoreline development index 5.0, volume of 0.23 km3, volume development of 1.3, and maximum, mean and relative depths of 33.9 m, 14.7 m and 0.7 %, respectively. The deep basin induces a monomictic pattern, with thermal stratification during the wet/warm season associated with anoxic bottom waters (1/3 of lake volume), and mixing during dry and cool season. Based on in situ measurements of tributary river discharges, theoretical retention time (RT) has been estimated in 13.4 years. The morphometry of Lake Nova promote long water RT and the warm monomictic mixing pattern, which is in accordance to the deep tropical lakes in Brazil.

Fitoplâncton do lago terra alta, Linhares, ES: dinâmica espaço-temporal

Devido a importância da agua para a manutencao dos ecossistemas e para diversas atividades humanas, tornam-se prioritarios estudos sobre a ecologia de corpos hidricos. Assim sendo, o presente estudo teve como objetivo avaliar a distribuicao espaco-temporal do fitoplâncton no lago Terra Alta (Linhares-ES). Foram feitas oito coletas, quatro no periodo seco e quatro no periodo chuvoso, em tres pontos amostrais e em duas profundidades (superficie e Zeu), para analises qualitativas e quantitativas. Foram avaliados para a comunidade fitoplanctonica: densidade, biomassa, frequencia de ocorrencia, especies abundantes e dominantes, indice de estado trofico e indices de riqueza, diversidade, equitabilidade e dominância. Testes nao parametricos com nivel de significância de p<0,05 foram aplicados para verificar diferencas entre as estacoes amostrais, profundidades e periodos, seco e chuvoso. O lago apresentou estratificacao no periodo chuvoso e coluna d’agua mais homogenea no periodo seco. A comunidade fitoplanctonica esteve composta por 85 taxons, distribuidos em 10 Classes, sendo Chlorophyceae (35%) e Cyanophyceae (30%) as mais representadas. Entre as cianobacterias foram encontradas oito especies ja registrados como toxicos no Brasil. Os coeficientes biologicos mostraram eutrofizacao se acentuando no lago, tendo, de acordo com o indice aplicado, variado de oligotrofico a eutrofico. A densidade e a biomassa variaram de 18 e 51x103Ind.ml-1 e 1,59 e 12,37mg.L-1, respectivamente. A diversidade se mostrou relativamente elevada chegando a 4,42, porem com media de 2,94. Foi registrada variacao sazonal (seca/chuva), porem com homogeneidade espacial. Nao houveram efeitos na estrutura da comunidade fitoplanctonica nem nas variaveis limnologicas analisadas em relacao a piscicultura, no entanto novas amostragens sao necessarias para a possivel pressao seletiva da piscicultura intensiva sobre a comunidade fitoplanctonica do lago.

Spatial and temporal distribution of thermotolerant coliform in Canal de Passagem (Vitória - ES) - related to physico-chemical parameters and tide

O Canal de Passagem, Vitoria, ES, e um sistema estuarino em processo de degradacao ambiental devido a descarga de esgoto in natura e semitratado. Os usos da comunidade do entorno dos recursos locais estuarinos sao conflitantes com a qualidade ambiental, o que pode oferecer riscos para a saude publica. Os objetivos do presente trabalho foram: 1. avaliar a distribuicao de coliformes termotolerantes dentro do HCP (metodo dos tubos multiplos), relacionando-a com a distribuicao das fontes de poluicao fecal, a dinâmica de mares e parâmetros fisico-quimicos, e 2. avaliar os resultados dentro das leis brasileiras de limites sanitarios para os variados usos da agua e balneabilidade. Amostras foram feitas espacialmente e temporalmente, visando cobrir o ciclo de mares de sizigia no inverno, outono e primavera, e tambem cobrindo uma quadratura e uma sizigia na amostragem no verao. Foram considerados os parâmetros sanitarios - coliformes termotolerantes, fisicos e quimicos e a acao das mares. Correlacoes significativas foram encontradas com o regime das mares e distribuicao de coliformes. A conclusao retirada do trabalho foi que a distribuicao de coliformes termotolerantes esteve relacionada com as fontes pontuais de poluicao, e as concentracoes foram diferentes entre as mares de quadratura e sizigia. Variacao entre tais mares nao e observada ate o momento pela Legislacao Brasileira para as aguas balneaveis.