Peltigera hydrothyria (Common name: Appalachian Water Fan) is endemic to mountainous regions of eastern North America where it is restricted to aquatic habitats in high quality mountain streams. It is imperiled by many factors including habitat destruction/degradation and climate change.
Peltigera hydrothyria is endemic to the Appalachian Mountains of eastern North America with scattered populations in suitable habitats in the Canadian Maritime Provinces and Quebec.
Demographic studies are needed to assess and monitor populations sizes. Many populations are known only from historical vouchers and have not been relocated in modern times. Although populations continue to be found throughout the range of the species, many of these are small and isolated. Based on the large number of historical populations and the extensive reduction of suitable habitat in range of the species, we consider the species to be in decline.
Population Trend: Decreasing
This species is restricted to slow moving, relatively small, cold mountain streams with high water quality and low turbidity.
The threats to this aquatic species are diverse and significant. The major threats stem from 1) changes in habitat (macro- and micro- scales) resulting from deposition of pollutants and ecosystem alterations, 2) changes in habitat (macro- and micro- scales) that are likely to result from climate change, 3) changes in habitat (macro- and micro- scales) resulting conversion and deterioration of natural habitats both historically and ongoing.
There are many conservation actions that can be taken including educating and training land managers and local botanists to identify the species so we can monitor its health, federally listing the species as endangered in the United States, improving numerous regulations and policies that would safeguard the aquatic habitats where the species occurs, and providing increased protection for buffer forest stands along riparian areas where the species occurs and could occur in the future.
The distribution of this species is well understood. Further research that will aid in the conservation of this species includes population assessments and monitoring, population genetics studies, and ecological studies that incorporate threats to the species. Additionally, a species recovery plan needs to be written for the United States.
Lendemer, J. C. & H. E. O’Brien 2011: How do you reconcile molecular and non-molecular datasets? A case study where new molecular data prompts a revision of peltigera hydrothyria s.l. in North America and the recognition of two species. - Opuscula Philolichenum 9: 99-110.
Lendemer, J. C./ F. Anderson 2012: Molecular data confirm the identity of populations of the water fan lichen from eastern Canada as peltigera hydrothyria s. str.. - Opuscula Philolichenum 11: 139-140
Miadlikowska, J./ D. Richardson/ N. Magain/ B. Ball/ F. Anderson/ R. Cameron/ J. C. Lendemer/ C. Truong/ F. Lutzoni 2014: Phylogenetic placement, species delimitation, and cyanobiont identity of endangered aquatic peltigera species (lichen-forming Ascomycota, Lecanoromycetes). . - American journal of botany 101(7): 1141-1156.