Hydrology Affects Environmental and Spatial Structuring of Microalgal Metacommunities in Tropical Pacific Coast Wetlands

RESEARCH ARTICLE Hydrology Affects Environmental and Spatial Structuring of Microalgal Metacommunities in Tropical Pacific Coast Wetlands Carmen Rojo1*, Francesc Mesquita-Joanes1, Juan S. Monrós1, Javier Armengol1, Mahmood Sasa3, Fabián Bonilla3, Ricardo Rueda2, José Benavent-Corai1, Rubén Piculo1, M. Matilde Segura1 1 Cavanilles Institute for Biodiversity and Evolutionary Biology, Universidad de Valencia, Paterna, Spain, 2 Departamento de Biología, Facultad de Ciencia y Tecnología, Universidad Nacional Autónoma de Nicaragua, León, Nicaragua, 3 Instituto Clodomiro Picado, Facultad de Microbiología, Universidad de Costa Rica, San José, Costa Rica * OPEN ACCESS Citation: Rojo C, Mesquita-Joanes F, Monrós JS, Armengol J, Sasa M, Bonilla F, et al. (2016) Hydrology Affects Environmental and Spatial Structuring of Microalgal Metacommunities in Tropical Pacific Coast Wetlands. PLoS ONE 11(2): e0149505. doi:10.1371/journal.pone.0149505 Editor: João Miguel Dias, University of Aveiro, PORTUGAL Received: May 26, 2015 Accepted: February 2, 2016 Published: February 22, 2016 Copyright: © 2016 Rojo et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Data Availability Statement: Two excel files (environmental and microalgal information) are available from the RODERIC database (accession addresses http://roderic.uv.es/handle/10550/48506 http://roderic.uv.es/handle/10550/48507). Funding: The authors acknowledge financial support from the Agencia española de coperación y desarrollo (http://www.aecid.es/ES), grants A1024073/09, A/031019/10, C/032994/10, A3/ 036594/11 received by JSM, CR, JA, FMJ, MS, FB and RR. This study was also funded by the Vicerrectoría de Investigación Universidad de Costa Abstract The alternating climate between wet and dry periods has important effects on the hydrology and therefore on niche-based processes of water bodies in tropical areas. Additionally, assemblages of microorganism can show spatial patterns, in the form of a distance decay relationship due to their size or life form. We aimed to test spatial and environmental effects, modulated by a seasonal flooding climatic pattern, on the distribution of microalgae in 30 wetlands of a tropical dry forest region: the Pacific coast of Costa Rica and Nicaragua. Three surveys were conducted corresponding to the beginning, the highest peak, and the end of the hydrological year during the wet season, and species abundance and composition of planktonic and benthic microalgae was determined. Variation partitioning analysis (as explained by spatial distance or environmental factors) was applied to each seasonal dataset by means of partial redundancy analysis. Our results show that microalgal assemblages were structured by spatial and environmental factors depending on the hydrological period of the year. At the onset of hydroperiod and during flooding, neutral effects dominated community dynamics, but niche-based local effects resulted in more structured algal communities at the final periods of desiccating water bodies. Results suggest that climatemediated effects on hydrology can influence the relative role of spatial and environmental factors on metacommunities of microalgae. Such variability needs to be accounted in order to describe accurately community dynamics in tropical coastal wetlands. Introduction According to metacommunity theory, community assembly processes can follow a neutral model or be explained by differences among species related mainly to the adaptation to local environmental factors and to differential dispersal abilities [1–2]. In that sense, geographical spatial extent of observation would partly explain biodiversity distribution [3–4]. One well stablished idea is that aquatic communities may be more strongly PLOS ONE | DOI:10.1371/journal.pone.0149505 February 22, 2016 1 / 15 Factors Structuring Microalgal Communities in Tropical Pacific Wetlands Rica (http://www.vinv.ucr.ac.cr/); grant 741-B1-517 received by MS and FB. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing Interests: The authors have declared that no competing interests exist. structured at large spatial extents by dispersal-related processes, evolution, and historical events [5–6] than by local environmental factors and biotic interactions. If attention is focused on the types of organisms or their traits, then body size is found to be inversely related to dispersal because decreasing size increases the dispersal rate of passively dispersing species [7–8]. That is, communities of smaller species are more controlled by the local environment while those of larger species are more strongly affected by space [1,9]. In fact, variance in the distribution of very small aquatic microorganisms such as diatoms can be explained by both local conditions and geographical distance [10–13]. Moreover, structure of microalgal metacommunities depends not only on different fractions of body sizes but also on life forms [6,13–14]. However, there are still few studies of microalgal metacommunities and even less on the different responses that depend on functional groups within microalgae [14]. An overview of the studies dealing with spatial and environmental effects on microalgal assemblages reveals a bias towards temperate areas. In those regions, the thermal regime follows a seasonal pattern that is considered very important for the structuring processes (the classic view by [15]). However, most studies consist of snapshot surveys, with some exceptions such as that of [11], who emphasize intra-interannual effects on diatom structuring and encourage other authors to consider dynamics in their studies of metacommunities. Therefore, there is a major gap in the analysis of spatiotemporal structure of aquatic communities from climatic regions with severe intra-annual hydrological changes, such as Mediterranean or tropical dry forest regions [6,16–18]. Moreover, in the Pacific Coast of Central America there are losses of original area covered by seasonal wetlands due to severe anthropic transformations [19–20]. Climate and anthropic changes are reducing aquatic systems in one of the most vulnerable tropical ecosystem, the tropical dry forest whose biodiversity is highly dependent on their wetlands [21]. However, and despite their important role, there is currently little information available on the conservation status of wetlands in this region [22–23]. Lack of information on tropical plankton communities and their structuring processes in wetlands and ponds [24] is a major drawback in view of the effects that the ongoing climate change is having on the sensitive algae to warmer scenarios and on the hydrological functioning of tropical dry forest [25–26]. In agreement (...truncated)