Aetokthonos hydrillicola gen. et sp. nov.: Epiphytic cyanobacteria on invasive aquatic plants implicated in Avian Vacuolar Myelinopathy

Abstract

Research into the taxonomy of a novel cyanobacterial epiphyte in locations where birds, most notably Bald eagle and American coots, are dying from a neurologic disease (Avian Vacuolar Myelinopathy-AVM) has been ongoing since 2001. Field investigations revealed that all sites where birds were dying had extensive invasive aquatic vegetation with dense colonies of an unknown cyanobacterial species growing on the underside of leaves. Morphological evaluation indicated that this was a true-branching, heterocystous taxon falling within the former order Stigonematales. However, 16S rRNA gene sequence demonstrated that it did not match closely with any described genus or species. More recent sequence analysis of the 16S rRNA gene and associated ITS region from additional true branching species resulted in a unique phylogenetic placement distant from the other clades of true-branching cyanobacteria. Light, epifluorescent, and transmission and scanning electron micrographs confirm the novel characteristics of this species, which is true-branching form with uniseriate basal filaments. It is encased within a firm sheath and has heterocytes both within the filaments and at the tips of the branches. The species is in a new genus of uncertain family assignment, and is herein named Aetokthonos hydrillicola gen. et sp. nov.

Identification of a new‐to‐science cyanobacterium, Toxifilum mysidocida gen. nov. & sp. nov. (Cyanobacteria, Cyanophyceae)

“…Several toxins produced by cyanobacteria have been recently reported and include an epiphyte found on Hydrilla implicated in avian vacuolar myelinopathy (Wilde et al. ), a microcystin‐producing member of the microbial community responsible for black band disease in corals (Richardson et al. , Casamatta et al.…”

ALTERNATE FOOD-CHAIN TRANSFER OF THE TOXIN LINKED TO AVIAN VACUOLAR MYELINOPATHY AND IMPLICATIONS FOR THE ENDANGERED FLORIDA SNAIL KITE (ROSTRHAMUS SOCIABILIS)

“…In 2009, we identified colonies of A. hydrillicola growing on hydrilla in Lake Tohopekaliga (Toho), in Kissimmee, Florida, US, and confirmed its identity with modifications to a previously validated PCR protocol Wilde et al 2014). In a 2007 survey of cyanobacterial epiphytes in 47 Florida lakes that included Toho, A. hydrillicola was confirmed by PCR only in Lake Huntley, a small lake approximately 160 km south of Toho (Williams et al 2009).…”

“…Aetokthonos hydrillicola dominates the epiphyte community on the leaves of SAV in AVM sites but is rare or not present in sites where AVM deaths have not occurred (Wilde et al 2005Williams et al 2007). Feeding studies have implicated food chain transfer (via ingestion of the gastrointestinal tract of diseased birds) of a toxin produced by a cyanobacterium associated with submerged aquatic vegetation growing in waterbodies where AVM-positive birds were previously diagnosed Birrenkott et al 2004;Lewis-Weis et al 2004;Rocke et al 2005;Wilde et al 2005Wilde et al , 2014. Thus, the working hypothesis of all ongoing AVM investigations is that waterbirds develop AVM by ingesting SAV and A. hydrillicola either directly or via predation on other birds that have recently fed on this material.…”

Molecular characterization of Geitleria appalachiana sp. nov. (Nostocales, Cyanobacteria) and formation of Geitleriaceae fam. nov.

“…Observation and characterization was primarily completed with a Zeiss Axioskop with Nomarski DIC optics and a Macrofire digital camera (Optronics, Goleta, CA). SEM micrographs were prepared using standard protocols (Wilde et al 2014). Single filament isolation for PCR was conducted in accordance with Mareš et al (2015).…”