Sérgio de Melo

Bio: Sérgio de Melo is an academic researcher from Federal University of Rio de Janeiro. The author has contributed to research in topics: Phytoplankton & Eutrophication. The author has an hindex of 5, co-authored 5 publications receiving 1667 citations.

Towards a functional classification of the freshwater phytoplankton

Abstract: This paper considers the structure of freshwater phytoplankton assemblages and promotes a scheme of vegetation recognition', based upon the functional associations of species represented in the plankton. These groups are often polyphyletic, recognizing commonly shared adaptive features, rather than common phylogeny, to be the key ecological driver. Thirty-one such associations are outlined and the basic pattern of their distinctive ecologies is outlined. An invitation to other plankton scientists to assist in the development of this scheme is issued.

Phytoplankton in an Amazonian flood-plain lake (Lago Batata, Brasil): diel variation and species strategies

Abstract: Phytoplankton diel variations in an Amazonian flood-plain lake (Lago Batata) were studied quarterly for 1 year, according to the hydrometric level fluctuation of the Trombetas river (39.7-47.0 m over sea level), to which the lake is permanently connected. Hydrological and hydro- graphic conditions determined mixing patterns of the water column and phytoplankton distribution. When the lake is deep (>4.0 m), sparse phytoplankton communities are found at the bottom, by thermal discontinuities, and may remain so for a short duration (days). When the lake is shallow (<4.0 m), mixing of the waters ensures a nearly even distribution of organisms throughout the water column. The weak stability of stratification is a major influence on the distribution of phytoplankton popu- lation densities in this shallow flushed lake. The highest phytoplankton densities during the second part of the day, mentioned in the literature, are observed only during decreasing water level. During the other phases of the hydrological cycle (increasing, high and low water levels), no differences in phytoplankton population density were observed throughout the diel cycle. Assemblages, or groups of descriptor species of systems having similar features, have recently been proposed. Assemblages of flushing-tolerant nano-algae (X1) and of mixing-dependent species (T, S) have shown that the physical properties of the environment were often the strongest determinants of the phytoplankton strategies.

Phytoplankton species composition is more sensitive than OECD criteria to the trophic status of three Brazilian tropical lakes

Abstract: We compared the structure and function of the phytoplankton community in three tropical systems in Brazil: an oligo-mesotrophic floodplain lake; an eutrophic reservoir; and a hypereutrophic coastal lagoon. Phytoplankton biomass increased along this trophic gradient averaging 2.6, 6.2 and 31.6 mm3 1−1 in the lake, reservoir and lagoon, respectively. Similarly, production increased from 427 to 918 gC m−2 y−1. Along the trophic gradient, diversity and species richness of phytoplankton decreased. There was, however, no relationship between trophy and rates of change of phytoplankton communities or the ratio of maximum/mean biomass. Phytoplankton size varied between systems with small algae (2–20 μm) dominating in the hypereutrophic lagoon and larger algae (20–200 μm) dominating in the other systems. Many of the trophic indices developed for temperate areas could not be applied to these tropical systems since there was no clear relationship between Secchi depth, chlorophyll, or TP and trophic status. Phytoplankton species may be more useful than these trophic indices to the classification of the condition of tropical lakes.

Taxonomy and ecology of Synedropsis roundii sp. nov. (Bacillariophyta) from a tropical brackish coastal lagoon, south-eastern Brazil

Abstract: A new Synedropsis species is described from a coastal tropical lagoon in south-eastern Brazil. This species has a single chloroplast in both views of the valve, apical pore fields composed of three slits, and uniseriate striae. It is planktonic and was found in brackish water. Synedropsis roundii is the eighth Synedropsis species to be described and the first to be found in a tropical region. We studied the seasonal dynamics of S. roundii, which can form blooms in the coastal Imboassica Lagoon, Rio de Janeiro stale, Brazil. Continuous mixing of this shallow environment is suggested to be an important physical factor determining the success of the species. Availability of soluble reactive silicon is thought to be the main factor regulating the large biomass fluctuations. In the classification of Reynolds in 1997 (Vegetation processes in the pelagic: a model for ecosystem theory. Ecology Institute, Oldendorf, Germany, 371 pp.), S. roundii appears to belong to D-assemblage, a set of small and fast-g...

Pseudo-nitzschia brasiliana (Bacillariophyceae), uma diatomácea oportunista da costa do estado do Rio de Janeiro, Brasil

Abstract: The occurrence of Pseudo-nitzschia brasiliana Lundholm, Hasle & Fryxell, a recently described marine diatom, is reported for two distinct environments on the coast of the state of Rio de Janeiro, Brazil, during the El Nino-ENSO summer of 1998. These occurrences took place almost simultaneously, as a bloom event, which is defined here not only through high cell abundance, but also in terms of high relative contribution to total cell numbers. The booms occurred at times when each one of these environments was under a specific stress, suggesting an opportunistic behavior for this diatom. In Sepetiba Bay, P. brasiliana was the first species to dominate (2.8 x 106 cells l-1; 85% of the microphytoplankton fraction) after a bloom of the raphidophyte Chattonella sp. was subsiding in early February. In Imboassica Lagoon, a oligohaline coastal system ca. 150km north of Sepetiba Bay, P. brasiliana was the dominant species (1.3 - 3.6 x 107 cells l-1; 90% of total phytoplankton) after the lagoon-sea connection was forced opened in mid-February, which allowed the contribution of more saline waters into the lagoon, that probably carried out a seed-stock of P. brasiliana present along the coast during this period.

The Ecology of Phytoplankton

Abstract: Communities of microscopic plant life, or phytoplankton, dominate the Earth's aquatic ecosystems. This important new book by Colin Reynolds covers the adaptations, physiology and population dynamics of phytoplankton communities in lakes and rivers and oceans. It provides basic information on composition, morphology and physiology of the main phyletic groups represented in marine and freshwater systems and in addition reviews recent advances in community ecology, developing an appreciation of assembly processes, co-existence and competition, disturbance and diversity. Although focussed on one group of organisms, the book develops many concepts relevant to ecology in the broadest sense, and as such will appeal to graduate students and researchers in ecology, limnology and oceanography.

Towards a functional classification of the freshwater phytoplankton

Abstract: This paper considers the structure of freshwater phytoplankton assemblages and promotes a scheme of vegetation recognition', based upon the functional associations of species represented in the plankton. These groups are often polyphyletic, recognizing commonly shared adaptive features, rather than common phylogeny, to be the key ecological driver. Thirty-one such associations are outlined and the basic pattern of their distinctive ecologies is outlined. An invitation to other plankton scientists to assist in the development of this scheme is issued.

Trait-Based Community Ecology of Phytoplankton

Abstract: Trait-based approaches are increasingly used in ecology. Phytoplankton communities, with a rich history as model systems in community ecology, are ideally suited for applying and further developing these concepts. Here we summarize the essential components of trait-based approaches and review their historical and potential application to illuminating phytoplankton community ecology. Major ecological axes relevant to phytoplankton include light and nutrient acquisition and use, natural enemy interactions, morphological variation, temperature sensitivity, and modes of reproduction. Tradeoffs between these traits play key roles in determining community structure. Freshwater and marine environments may select for a different suite of traits owing to their different physical and chemical properties. We describe mathematical techniques for integrating traits into measures of growth and fitness and predicting how community structure varies along environmental gradients. Finally, we outline challenges and future directions for the application of trait-based approaches to phytoplankton ecology.

Use and misuse in the application of the phytoplankton functional classification: a critical review with updates

Abstract: Since its publication, the article ‘Towards a functional classification of the freshwater phytoplankton’ (Reynolds et al., J Plankton Res 24: 417–428, 2002), has attracted the attention of dozens of phytoplankton ecologists worldwide. These numerous applications of the functional classification to describe phytoplankton patterns in various aquatic ecosystems allowed the recognition of some uncertain features of this concept originating from various reasons. In this article, we attempt to facilitate the application of the functional classification, by providing a detailed description of the typical misplacements and by modifying some of the original habitat templates and species allocations. Furthermore, we discuss in this review those coda that were additionally described after the publication of the original article, and attempt giving an overview, as complete as possible, of the state of art.