The phytoplankton of Guanabara Bay, Brazil: I. historical account of its biodiversity

Abstract

This is a historical account of the biodiversity of phytoplankton in Guanabara Bay, Brazil. It is based on 57 publications that refer to sampling carried out between 1913 and 2004. The publications included are those with direct microscopic identification. Although 80% of the studies focus on ecological issues that tend to mention only the most abundant species, 24 publications provide comprehensive check-lists at the species level, especially of taxa ≥ 20 µm. The inventory of species includes, to date, 308 taxa among 199 diatoms, 90 dinoflagellates, 9 cyanobacteria, 5 euglenophyceans, 1 chlorophycean, 1 prasinophycean, 1 silicoflagellate, and 2 ebriids. The most conspicuous species were the dinoflagellate Scrippsiella trochoidea and diatoms from the Skeletonema costatum complex. The first was the theme of the very first publication in the area (Faria 1914) that reported on its bloom associated with the mass mortality of fish due to oxygen depletion; it is still often found in high abundances (10 6 cell.L -1) in more protected areas. The second was long considered in the literature as a cosmopolitan and opportunistic species, until the recent discovery of cryptic species within the genus; taxonomic re-evaluation of local populations is, therefore, needed. Besides these two species, only other 25 species stood out in terms of frequency of occurrence and widespread distribution in the Bay, some known to be implicated in harmful blooms elsewhere. The biodiversity of dinoflagellates, especially within the Gymnodiniales, and that of other unidentified flagellates (Haptophyceae, Cryptophyceae, Prasinophyceae, Raphidophyceae) is largely underestimated because of the use of fixatives that distort/destroy diagnostic characters. From the initial inventory of 124 taxa published in 1917 and the subsequent additions in species numbers, one can have a false perception that the phytoplankton biodiversity has increased throughout the years, despite the overall increase in eutrophication observed in Guanabara Bay. The reason for this may be twofold: 1) it is an artifact caused by our progressively improving technical capability to detect and identify species and 2) the possible effects of eutrophication could be better perceived when the community structure is evaluated, that is, when space-time variations in the abundances of the populations (rather than just number of species) are also taken into account. Resumo: Este é o histórico dos estudos sobre a biodiversidade do fitoplâncton da Baía da Guanabara, Brasil, com base em 57 publicações relativas a amostras coletadas no período entre 1913 e 2004. Estão aqui incluídas apenas as investigações que identificaram espécies por microscopia. Apesar de 80% dos estudos serem de cunho ecológico, os quais tendem a citar apenas as espécies mais abundantes, 24 publicações incluem listas completas dos táxons identificados em nível específico, especialmente daqueles ≥ 20 µm. Atualmente, o inventário de espécies inclui 308 táxons dentre 199 diatomáceas, 90 dinoflagelados, 9 cianobac...

Phytoplankton community structure in one sector of Guanabara Bay (RJ, Brazil) during 2011 and 2012

“…Some taxa such as species of the genus Protoperidium and of the Order Gymnodiniales, considered heterotrophics (STEIDINGER; TANGEN, 1997), have also been frequently observed in samples. The high contribution of organisms of the Order Gymnodiniales to richness and abundance confirms VILLAC and TENENBAUM (2010) statement that Guanabara Bay dinoflagellates, although frequent and highly representative, are underestimated by virtue of the sampling and analysis procedures used in most of the studies. These dinoflagellates have extremely fragile cells that are deformed or destroyed by the commonly used fixative substances.…”

Spatial distribution of intertidal sandy beach polychaeta along an estuarine and morphodynamic gradient in an eutrophic tropical bay

“…The effect of hypereutrophic conditions in the western area of the bay is shown by phytoplankton assemblages, where a larger contribution of the autotrophic microplankton fraction and higher species numbers is found at the entry of the bay when compared to the west area (Villac and Tenembaum, 2010). One of the effects of the eutrophication impact is the depletion of oxygen levels, excluding aerobic organisms and the dominance of anaerobic bacteria populations that support the benthic microbial foodweb of the bay (Silva et al, 2008).…”

Estuary Adjacent to a Megalopolis as Potential Disrupter of Carbon and Nutrient Budgets in the Coastal Ocean

“…Chl-c is also a significant component of the photosynthesized pigments and such observation concurs with the reported abundance of dinoflagellates in the bay. 52,53 Heterotrophic bacteria are important for the structure and dynamics of food chains, as well as for the biogeochemical cycles, being responsible for the inter-conversion of DOC and POC in the carbon cycle. 54 Bacterioplankton (Table 1) although variations with tide were very intense as indicative of the heterogeneity of the system.…”