Transcending marine turtles: first report of hatching failure in eggs of
Amazonian freshwater turtles with symptoms of the fungal emerging
disease fusariosis
Abstract
In the last decades fungal pathogens are causing devastating population
declines across a broad range of taxa. A newly emerging fungal disease,
sea turtle egg fusariosis, caused by members of the Fusarium
solani species complex (FSSC), has been reported to be responsible for
hatching failure in sea turtles around the world. However, this has not
been reported in other non-marine turtle species. Herein we report high
hatching failure from eggs symptomatic of fusariosis in the
yellow-spotted Amazon river turtle ( Podocnemis unifilis),
inhabiting a pristine environment in the Ecuadorian Amazon. We assessed
hatching success from eggs symptomatic and asymptomatic of fusariosis (
n = 680 eggs), tested for Fusarium infection by PCR
amplifying the TEF-1α gene (n= 68 turtle internal egg swab samples) and
sequenced eight amplicons for screening of FSSC membership on an
Illumina Miseq. Hatchability was 72% for asymptomatic eggs, whilst only
8% of symptomatic eggs hatched. Eight percent of asymptomatic and 58%
of symptomatic eggs tested positive for Fusarium spp. and
sequencing revealed that nine sequence variants from three asymptomatic
and four symptomatic eggs corresponded to F. keratoplasticum, F.
solani and F. falciforme, the three major FSSC pathogens already
reported in sea turtle egg fusariosis. Our study therefore suggests that
observed hatching failure of eggs showing symptoms of fusariosis is at
least partially caused by Fusarium pathogens within FSSC in a
freshwater turtle. This report highlights that fusariosis is more
widespread among the Testudines order than previously reported and is
not limited to sea environments, which is of particular conservation
concern.