Freshwater ascomycetes are microscopic fungi that decompose dead plants and wood in aquatic habitats. These fungi play an important role in aquatic food webs by breaking down complex plant materials into more digestible components that can then be used by aquatic invertebrates and bacteria as a food source. Despite evidence of the ecological role of freshwater ascomycetes as decomposers in water, there is a lack of knowledge of their identities, geographical distributions, species diversity patterns, and evolutionary relationships. The continued degradation and loss of aquatic habitats due to anthropogenic activities make it imperative to study these fungi now from undisturbed habitats that still exist. Drs. Carol Shearer and Andrew Miller and their students will collect, identify, and isolate freshwater ascomycetes along an altitudinal gradient from the tropical Andes to the Amazonian Basin in southeastern Peru. This region, currently nearly unstudied for freshwater ascomycetes, is a global conservation priority area and one of the few remaining large tracts of forests extending from the tree line to the lowlands. The ecological habitats from tree line to lowlands lie along a climate gradient that will allow the investigators to determine how climate influences species composition. The health and sustainability of freshwater ecosystems are relevant to a broad scope of political, economic, societal and public health interests. For aquatic ecosystems which are vital to humankind biologically, commercially and aesthetically, but which suffer from numerous anthropogenic activities, there an urgent need to understand the species responsible for ecological function and ecosystem health. This project will provide student training in the collection, identification and isolation of freshwater ascomycetes, which perform the vital function of decomposing dead matter in freshwater ecosystems. The researchers will establish cultures of these fungi that will constitute a diverse source of new genetic living stocks. These cultures will provide material for systematic, developmental, physiological, molecular, and ecological studies. The researchers will contribute voucher specimens, cultures and molecular sequences to established repositories, thereby providing material and data for future studies, including molecular assessment of biodiversity by ecologists. In addition to publishing the results of their study in scientific journals, the scientists will place descriptions of new and unusual species on the Freshwater Ascomycetes Web Site (http://fungi.life.uiuc.edu/).
Intellectual Merit Scientists Dr. Carol Shearer and Dr. Andrew Miller and their students of the University of Illinois at Urbana-Champaign, Illinois conducted a survey of freshwater Ascomycetes (Kingdom Fungi) of tributaries of the Madre de Dios River in Peru, which is part of the Amazon River Basin. Freshwater ascomycetes play an essential ecological role as decomposers of dead plant material such as wood and leaves that fall or are washed into aquatic habitats. As a result of their decomposition activities plant material is broken down chemically into food components that can be digested by stream invertebrates. Thus these fungi are essential to food webs in freshwater habitat. Although freshwater ascomycetes play a very important role in freshwater habitats, compared to other aquatic organisms such as fish, invertebrates and algae, they have been studied only recently and by only a few investigators. Thus our knowledge gap about the taxonomy, phylogeny, and geographical distribution about this group is enormous. To address this knowledge gap and as a continuation of their ongoing research on freshwater ascomycetes, Shearer and Miller undertook a study of species in the Neotropics. They selected Peru for study because it contained mountainous regions in addition to lowland tropical forests thereby providing a variety of aquatic habitats along an elevational gradient ranging from 218 to 3870 meters above sea level. Samples of submerged woody debris and palm debris were placed in moist plastic bags and mailed to the University of Illinois for processing. Samples were examined microscopically and ascomycetes were identified, isolated, photographed and prepared for deposit in herbaria. Over 300 species were collected and all were new reports for Peru and many were new reports for South America. With funds from this grant, we described one new family, 10 new genera and 24 new species. Some of these species may be viewed on the Freshwater Ascomycetes web page (See Monograph Section at http:www.fungi.life.illinois.edu. As a result of their studies, the investigators established the first species list vouchered by herbarium specimens, cultures and sequence data for fungal decomposers inhabiting aquatic habitats along an altitudinal gradient in South America. Their work revealed that aquatic ascomycetes follow the same distribution pattern with respect to altitude as most other organisms do, i.e., in having a species maximum at mid-altitudes and fewer species at higher and lower altitudes. Very few species occurred throughout the entire altitudinal gradient. Comparison of data from this study and other studies in the Paleotropics suggests that a pantropical freshwater ascomycota exists. Further studies of Central and South America and Africa are needed to confirm these initial observations. The investigators have shown that, thus far, ITS barcoding works relatively well for freshwater ascomycetes. In connection with their molecular work, 151 sequences have been deposited in GenBank and six alignments in TreeBase. Broader Impacts This study has provided a vouchered record of freshwater ascomycetes that occur in a Peruvian river along a latitudinal gradient. Given the importance of these fungi in stream and river food webs, such a record is important in assessing the effects of water pollution, clearcutting, gold mining, dam construction and global warming on fungal communities and fungal activities in aquatic habitats. Loss of freshwater ascomycetes will influence the processing rates of woody and herbaceous debris and the structure of food webs, thus possibly the fish productivity of aquatic habitats. As the world population continues to grow, the demands for clean water increase. It may be likely that enzymes present in freshwater ascomycetes can ameliorate some types of chemical pollution. Cultures from this study are important to Peruvians for enzyme and functional studies. In the course of this study, one post-doc, one Ph.D. students and four undergraduates were trained in all aspects of this study. Although the undergraduates may go on to careers in other fields, they retain their interests in aquatic mycology/ecology. The post-doc and Ph.D. students are already training students in South America about freshwater ascomycetes. The Freshwater Ascomycetes web page has been accessed by at least one individual from every country in the world. Many researchers in Europe and Asia use this site frequently for all types of information.
