Ecological guilds of epiphytic diatoms (Bacillariophyta) on Acrostichum danaeifolium Längst. &amp; Fisch in a subtropical wetland in southern Brazil

Vanessa Corrêa Da Rosa,Marinês Garcia

doi:10.1590/s2179-975x4214

Abstract

Abstract Aim: Seasonal patterns diatom community on Acrostichum danaeifolium were examined in a wetland in southern Brazil. Methods The adhered diatoms were removed from the plant, species identification and growth forms were performed, and determined physical-chemical parameters of water. Results In total, 96 taxa belonging to 46 genera were identified. Nitzschia frustulum, Pseudostaurosira brevistriata and Plagiogramma tenuissimum were abundant species. Distinct growth forms that formed low-and high-profile ecological guilds and a mobile guild were observed. Navicula and Nitzschia were the genera with the greatest number of species, and these diatoms formed mucilage tubes. The water temperature varied from 10-26 °C, the depth from 0.35-0.80 m, the transparency from 0.20-0.23 m, the flow from 9.4-42.12 m3 s–1, the pH from 7.08-8.89, the electrical conductivity from 0.65-15.83 mS cm–1, the total organic phosphorus from 0.03-0.11 mg L–1, and the total organic nitrogen from 0.29-0.49 mg L–1. In summer, marine species such as Thalassiosira eccentrica and Rhaphoneis castracanii were also present. Conclusions The high-profile guild prevailed in all seasons of the year, with higher number of growth forms in the guild in winter. The richness found on A. danaeifolium shows that this plant provide a favorable habitat for epiphytic diatoms in wetlands such as Lagoa Pequena.

Highlights

South America has large expanses of wetlands, and most of them (50%) are located in Brazil
The objective of this work was to determine the specific composition of epiphytic diatom community on A. danaeifolium and the ecological guilds that are present, as well as to determine which environmental factors influence the presence of these guilds
The Pseudônimo stream (31°40’16,4” S and 52°04’51,4” O) is a water course connected to the Patos Lagoon estuary and is associated with the spillway of Lagoa Pequena, a Brazilian subtropical wetland located in the coastal plain of Rio Grande do Sul (Figure 1)

Summary

Introduction

South America has large expanses of wetlands, and most of them (50%) are located in Brazil. In the State of Rio Grande do Sul, the Lagoa Pequena is a wetland designated as a conservation priority (Base de dados tropical, 2003). A. danaeifolium has been described in mangrove areas of Costa Rica, Puerto Rico and Mexico (Coll et al, 2001; Mehltreter & Palacios-Rios, 2003; Sharpe, 2010). The species occurs in the United States (Florida), Paraguay, Brazil (Mehltreter & Palacios-Rios, 2003), the inshore and Amazon regions of Peru (Leon & Young, 1996) and in the wetlands of Bolivia (Killen & Schulenberg, 1998). In the state of Rio Grande do Sul (Brazil), it occurs in the Tramandaí wetland (Sehnem, 1972)

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