Benthic soft-bodied algae as bioindicators of stream water quality

Knowledge and Management of Aquatic Ecosystems (2016) 417, 15 c R. Stancheva and R.G. Sheath, published by EDP Sciences, 2016  DOI: 10.1051/kmae/2016002 Knowledge & Management of Aquatic Ecosystems www.kmae-journal.org Journal fully supported by Onema Review Open Access Benthic soft-bodied algae as bioindicators of stream water quality R. Stancheva and R.G. Sheath Department of Biological Sciences, California State University San Marcos, San Marcos, 333 S. Twin Oaks Valley Rd., California 92096-0001, USA Received December 13, 2015 – Revised January 21, 2016 – Accepted January 25, 2016 Abstract – This review presents the state-of-the-art of benthic soft-bodied algae as biondicators of stream and river water quality, with emphasis on bioassessments set by the legislation (e.g., European Water Framework Directive, USA Clean Water Act) to promote the restoration and ensure ecological sustainability of water resources. The advantages and shortcomings of a variety of bioassessment field and laboratory methods for algae are discussed. The increasing use of soft-bodied algae in biotic indices to assess individual anthropogenic stressors, and in multimetric indices of biotic integrity to evaluate ecological condition in streams is summarized. Rapid microscopic and molecular approaches for inferring nutrient supply with heterocystous cyanobacteria and other sensitive algae are proposed. The need of better understanding of soft-bodied algae as bioindicators is discussed and suggestions are made for obtaining meaningful bioassessment information with cost-efficient efforts. Key-words: Bioassessment / water quality / benthic soft-bodied algae / stream / river Résumé – Les algues benthiques à corps mou comme bioindicateurs de la qualité de l’eau en rivière. Cette revue présente l’état de l’art des algues benthiques à corps mou comme bioindicateurs de la qualité de l’eau en rivière, avec un accent sur l’évaluation biologique fixée par la législation (par exemple, la directive européenne cadre sur l’eau, le Clean Water Act USA) pour promouvoir la restauration et assurer la durabilité écologique des ressources en eau. Les avantages et les inconvénients de diverses méthodes de bioévaluation de terrain et de laboratoire pour les algues sont discutés. L’utilisation croissante des algues à corps mou dans les indices biotiques pour évaluer les facteurs de stress anthropiques, et les indices multimétriques d’intégrité biotique pour évaluer l’état écologique des cours d’eau est présentée. Les approches rapides microscopiques et moléculaires avec des cyanobactéries hétérocystées et d’autres algues sensibles pour déduire l’apport de nutriments sont proposées. La nécessité d’une meilleure compréhension des algues à corps mou comme bioindicateurs est discutée et des suggestions sont faites pour obtenir de bonnes données de bioévaluation d’un bon rapport coût-efficacité. Mots-clés : évaluation biologique / qualité de l’eau / algues benthiques à corps mou / courant / rivière 1 Introduction In streams, benthic algae are one of the most species-rich organism groups (Meyer, 2007) and the rationale for their use in bioassessments has been summarized in previous reviews (see Whitton and Kelly, 1995; Lowe and Pan, 1996; Stevenson and Smol, 2003; Stevenson, 2014). The most important advantages of benthic algae over other stream organisms as bioindicators are outlined as follows: (a) benthic algae are sessile, or have limited movement, and they cannot avoid potential pollution through migration or other means, and thus they must either tolerate the ambient environment or perish; (b) the generation time ranges from a few days for unicellular organisms to several months for larger multicellular, filamentous and colonial soft-bodied algae (belonging to all non-diatom algal taxonomic groups, including cyanobacteria) and thus short- and long-term shifts in environmental conditions can be observed (Jarlman, 1996; Whitton, 2012); (c) algae have  Corresponding author: species-specific environmental tolerances and preferences and directly respond to water chemistry (such as nutrient levels, salinity, pH, organic pollution, herbicides, etc.); (d) benthic algal communities are typically species-rich and spatially compact, so a few square centimeters of substratum may support over a hundred species, each one with specific environmental requirements, and thus represents an information-rich system for environmental monitoring (modified from Lowe and Pan, 1996). Compared to macroinvertebrates and fish, algae are better suited for local-scale or upstream-downstream studies and better indicate water chemistry and land use that alters water quality, because of their position at the base of food webs and restricted motility (Johnson, 2006; Resh, 2008). Due to their desiccation tolerance, algae could be the only water quality bioindicator in intermittent streams in more arid areas. Ecological indicators, which are measurable structural or functional characteristics of the ecosystems, including biological conditions (USEPA, 2002) are central to bioassessment, with their primary role being to evaluate ecosystem responses This is an Open Access article distributed under the terms of the Creative Commons Attribution License CC-BY-ND (http://creativecommons.org/licenses/by-nd/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. If you remix, transform, or build upon the material, you may not distribute the modified material. R. Stancheva and R.G. Sheath: Knowl. Manag. Aquat. Ecosyst. (2016) 417, 15 to anthropogenic stress (i.e., deviation from ecological integrity, Niemi and McDonald, 2004). Algae are bioindicators of both structural components of ecological integrity (taxonomic composition) and functional integrity (biomass, rates, pattern and relative importance of processes) (Dolédec and Statzner, 2010). The water-quality criteria in countries around the world are established by legislation and large-scale bioassessment projects are designed to evaluate the stream health and to support water resource management decisions. The goal of the USA Clean Water Act (CWA, 1972) is to restore and maintain the physical, chemical, and biological integrity of water resources and to have surface waters with biological integrity, defined as “the capability to support and maintain a balanced, integrated, adaptive community of organisms having species composition, diversity, and functional organization comparable to that of natural habitat of the region” (Frey, 1977). Biological condition is usually measured in terms of deviation from a natural or minimally disturbed condition, and reference conditions for biological integrity refers to the “naturalness” of the structure and function of the biota in the absence of significant human disturbance or alteration (Stoddard et al., 2006). Similar water-quality governmental policies and guidance are developed in (...truncated)