Spatial and temporal distribution of stream macroalgae in a tropical river basin

Abstract

Spatial and temporal distribution of stream macroalgae in streams from southeastern Brazil were assessed for one year. The fluctuations in macroalgal species composition and environmental factors were monitored monthly. The region exhibit a tropical climate, with defined rainy and dry seasons. Nineteen species were found, with a predominance of Chlorophyta (52.7% of the species), followed by Cyanobacteria (26.3%), Ochrophyta and Rhodophyta (10.5% each). Scytonema arcangeli had the highest number of records (63.6%), while Mougeotia capucina occurred in all sampling sites. Community structure had low similarity (20-26%) and the environmental factors showed a weak contribution to the distribution pattern observed. Despite this, the light availability at the stream-bed seems to be a major influence on the macroalgal seasonal dynamics. We suggest that macroalgae communities are predominantly composed of rare species, and this could explain the lack of a clear spatial and temporal variation pattern of these organisms.

Tropical lotic primary producers: Who has the most efficient photosynthesis in low‐order stream ecosystems?

“…The regional climate is defined as tropical with rainy summers and dry winters (Max et al, 2003). These streams have been regularly used for experimental ecological studies involving benthic primary producers, especially the algal component (see Tonetto, Peres, Hirata, & Branco, 2015).…”

Soft-bodied benthic algae in pristine Brazilian streams: from acid to karst

“…Such spatial differences have been observed in several studies carried out in the southeastern/southern regions of Brazil (e.g. Branco et al 2008b;2009;Tonetto et al 2015).…”

“…According to McCune & Grace (2002, p. 31), "values of βw < 1 are rather low and βw > 5 can be considered high". Branco et al (2008b) and Tonetto et al (2015) also described low similarity in macroalgal communities from southeastern/southern Brazil, with most taxa restricted to a single sampling site. In a dataset composed of almost 500 temperate streams (New York State and Austria), Rott & Wehr (2016) also reported few widely distributed taxa, without any ubiquitous ones.…”

“…In this context, site C2, the richest one, had the "best of all worlds"; it presented abundant macrophyte cover on the rocky bed, in an unshaded area of "crystal clear" waters. Since light availability is also recognized as a determinant abiotic factor for algal communities (Tonetto et al 2015), algal development at site C2 was positively influenced by the combination of light and macrophyte cover in abundance.…”

“…Salomoni et al 2011;França et al 2017) or macroalgal communities (e.g. Branco et al 2001;2008a;Necchi Jr. et al 2008;Tonetto et al 2015;, and the majority of them are concentrated in the southeastern/southern regions. Microscopic attached algae from other taxonomical groups are less known, which may lead to underestimated numbers for general phycological diversity in such environments.…”