TAXONOMY AND SPECIES COMPOSITION OF EPIPHYTIC ALGAE IN STA. CRUZ RIVER, LAGUNA (PHILIPPINES) Eldrin DLR. Arguelles*1, Rosario G. Monsalud1 Address(es): 1Philippine National Collection of Microorganisms, National Institute of Molecular Biology and Biotechnology (BIOTECH), University of the Philippine Los Baños, College, Laguna, Philippines, 4031. *Corresponding author: [email protected] https://doi.org/10.15414/jmbfs.2039 ARTICLE INFO ABSTRACT Received 15. 8. 2019 Algal epiphytes attached on three dominant aquatic macrophytes (Pistia striatotes, Eichhornia crassipes and Ipomoea aquatic) were Revised 7. 8. 2021 investigated as part of a preliminary study on the ecological assessment of Sta. Cruz River, which has been used primarily for Accepted 12. 8. 2021 agriculture and fishery. In total, 22 algal taxa were identified on the studied macrophytes: 8 Chlorophyta, 4 Cyanobacteria, 7 Published xx.xx.201x Bacillariophyta, and 3 Euglenophyta. The taxa in this paper represent 8 classes, 16 orders, 20 families, 22 genera and 22 species based on the latest algal taxonomical nomenclature. Among these taxa, the existence of a rare filamentous cyanobacteria, Planktothrix compressa (Utermöhl) Anagnostidis et Komárek is described for the first time in the Philippines. A species of diatom is also reported in Regular article this study for the first time based on recent algal taxonomic nomenclature and this is Ulnaria ulna (Nitzsch) Compère that is based on the former name of Synedra ulna (Nitzsch) Ehrenberg. These taxonomic records proved that aquatic macrophytes represents a unique habitat for novel and diverse types of algal flora, which demands further investigations in the country. Keywords: Epiphytic algae, macrophytes, Philippines, river, taxonomy INTRODUCTION nutrients within the vertical expanse of the water column, inhibiting algal epiphytes as well as other submerged macrophytes from acquiring enough Macrophytes are aquatic and amphibious plants found in the littoral zones of resources for growth and survival (Schramm & Jirka, 1989). Moreover, running waters (eg. rivers, streams, and the like) and shallow lakes contributing morphology of several macrophyte species, specifically the length of stem and largely to the autochthonous carbon pool and oxygen budget of the aquatic leaves, may limit the growth and proliferation of algal epiphytes by releasing ecosystem (Janauer & Dokulil, 2006). These plants have a significant function inhibitory substances (allelochemicals) (Tunca et al., 2014). Thus, development in water biocenoses, hydrology and sediment dynamics, biochemical cycles, of algal epiphyton community as well as its distribution and abundance depend structuring and altering the physico-chemical features (of an aquatic ecosystem) largely on macrophyte host species. On the other hand, in situations where there by photosynthesis, mineralization, and decomposition (Jeppesen et al., 2002; is an evident increased in algal epiphyte population, it is observed that there is a Joniak et al., 2007; Špoljar et al., 2012). Macrophytes have diverse species of reduction in the total macrophyte biomass density due to restriction in nutrient microalgae attached to submerged plant parts which have been shown to be an diffusion from the water to host plant (Fawzy, 2016). In the Philippines, important productive component of the aquatic ecosystem (Sheldon & Boylen, taxonomic studies of algal epiphytes associated to different macrophytes were 1975). Algal epiphytes form a matrix system of microalgae and cyanobacteria done only to those plant species inhabiting Laguna de Bay (Rañola, et al., 1990; attached to submerged aquatic macrophytes. These algae are regarded as primary Arguelles, 2019 a,b,c; Arguelles, 2020a). To date, a total of 82 taxa of algal species in different lotic water systems and are involved in maintaining epiphytes associated with four dominant aquatic macrophytes (Hydrilla ecological balance among the different groups of macrophytes and aquatic verticilata, Nymphaea pubescens, Eichhornia crassipes and Ipomoea aquatic) organisms (Hassan, et al., 2014; Fawzy, 2016). It is widely recognized that these found in Laguna de Bay were documented in in the Philippines. These taxonomic organisms supply food to invertebrates, fish, and in other aquatic fauna in the surveys reported the occurrence of five rare microalgae – namely, Cryptoglena littoral zone and contributes an estimated of 0.2% to 41% of the total primary skujae Marin and Melkonian, Pseudanabaena minima (G.S. An) Anagnostidis, production in an aquatic ecosystem (Laugaste & Ruemamen, 2005; Effiong & Synechococcus nidulans (Pringsheim) Komárek, Chroococcus schizodermaticus Inyang, 2015). Several observational and experimental studies on ecological West and Franceia amphitricha (Lagerheim) Hegewald – for the first time in the status of bodies of water showed an increase in the population and diversity of Philippines. Also, some of the microalgal genera documented in these taxonomic algal epiphytes in response to nutrient loading and pollution (Gil et al., 2006; studies (eg. Cryptoglena, Tetradesmus, Nitzschia, Euglena, Chroococcus, Peterson et al., 2007; Fawzy, 2016). This led to the consideration of these Oscillatoria, Phacus and Chlorella) are usually associated with organically organisms as excellent bioindicators of environmental and water quality polluted enriched waters (Arguelles, 2019 a,b,c; Arguelles, 2020a). These algal alterations because of its sensitivity to external sources of pollution (Lowe, 1996; epiphytes are regarded as good indicators of environmental changes and water Fawzy, 2016). Species of algal epiphytes associated with organically polluted quality due to their sensitivity to external sources of fertilization which can be enriched waters include Euglena, Phacus, Nitzschia, Chlorella, Scenedesmus, use in the assessment of ecological status of Laguna de Bay (Arguelles, 2020a). Chlamydomonas, Cladophora, and Closterium (Effiong & Inyang, 2015). The taxonomic records reported in these studies provided baseline information The biological interconnection and relationship between algal epiphytes and host regarding distribution and diversity of Philippine epiphytic algae from aquatic aquatic macrophyte in the aquatic environment are still limited and incompletely macrophytes found in local freshwater habitat. studied (Wetzel, 1996). Several reports suggested that biotic and abiotic factors Diversity and ecological studies of epiphytic microalgae of different aquatic such as physico-chemical characteristics of submerged parts (stem, leaves and macrophytes found in running waters (such as rivers and streams) in the roots) of macrophytes, availability of substrates, temperature, light intensity and Philippines remain poorly understood. To date, no documented taxonomic survey grazing affects the diversity and prevalence of epiphytic algal community (Gil et was conducted on these group of microalgae. Thus, additional taxonomic survey al., 2006; Fawzy, 2016). Aquatic macrophytes are sometimes detrimental for of algal epiphytes of different aquatic macrophytes found in these aquatic algal epiphytes since they are capable of monopolizing light and assimilate ecosystems are needed to deepen our understanding of the diversity and 1 J Microbiol Biotech Food Sci / Arguelles and Monsalud et al. 20xx : x (x) e2039 ecological roles of these microorganisms. The goal of this investigation is to and comprised 36.36% of all recorded taxa. Bacillariophyta, Cyanobacteria and account the species diversity of algal epiphytes associated to different aquatic Euglenophyta represented 31.81%, 18.18% and 13.63% of all recorded taxa, macrophytes observed in Sta. Cruz River, one of the 21 major tributary rivers of respectively. The taxonomic list of the algal epiphytes determined in Sta. Cruz Laguna de Bay. Also, morphotaxonomic description of each algal taxa were River is given in Table 1. All the taxa are systematically enumerated with documented together with a brief description of the sampling sites and natural morphotaxonomic descriptions along with a simple habitat information where the environment of its existence. alga was observed. Illustrative photomicrographs of some of the algal species are given in Plates I-IV. Currently accepted algal taxonomic names were used based MATERIAL AND METHODS on the recent nomenclatural indices for algae of the International Association of Plant Taxonomy (IAPT) and Round et al. (1990). Study Site Dichotomous Key Sta. Cruz River is considered as one of the main branch rivers of Laguna de Bay. It lies at 14.3001 oN and 121.4068 oE, specifically within the municipalities of 1. Cells without membrane-bound organelles ………...……..……….……….. 2 Liliw, Magdalena, Nagcarlan, Pagsanjan, Pila, and Sta. Cruz (Figure 1). The river 1. Cells with membrane-bound organelles.…….…..………………..……...…. 5 is measured to be approximately 14.48 km in length, flowing towards Laguna de Bay. Currently, the principal use of this river is for fishery and agriculture (with 2. Unicellular and spherical occurring as singly or in clusters of 2 to 4 cells ... coconut and rice production, livestock, poultry, and piggery raising as main Chroococcus minutus activities). This body of water is known to be a receptacle for floodwaters coming 2. Filamentous occurring as single or in groups of trichomes …………………3 from its small tributary rivers such as Maimpis river, Liliw river, San Diego river, Tipacan river, and Talahebeng river (Madamba et al., 1992). 3. Filamentous cyanobacteria exhibiting