Journal of Threatened
Taxa | www.threatenedtaxa.org | 26 December 2024 | 16(12): 26234–26239
ISSN 0974-7907 (Online)
| ISSN 0974-7893 (Print)
https://doi.org/10.11609/jott.8940.16.12.26234-26239
#8940 | Received 01
February 2024 | Final received 22 November 2024 | Finally accepted 02 December
2024
Citizen science
conservation: a case study using two threatened large aquatic
American salamanders
(Amphibia: Urodela), the Common Mudpuppy Necturus maculosus (Proteidae) and the Eastern Hellbender Cryptobranchus
alleganiensis (Cryptobranchidae)
observations on iNaturalist
Shem Unger
Biology Department,
Wingate University, Wingate, North Carolina 28174, USA.
s.unger@wingate.edu
Editor: S.R. Ganesh, Kalinga Foundation, Agumbe, India. Date
of publication: 26 December 2024 (online & print)
Citation: Unger, S. (2024). Citizen
science conservation: a case study using two threatened large aquatic American
salamanders (Amphibia: Urodela), the Common Mudpuppy Necturus maculosus
(Proteidae) and the Eastern Hellbender Cryptobranchus alleganiensis
(Cryptobranchidae) observations on iNaturalist. Journal of Threatened
Taxa 16(12): 26234–26239. https://doi.org/10.11609/jott.8940.16.12.26234-26239
Copyright: © Unger 2024. Creative Commons Attribution 4.0 International License. JoTT allows unrestricted use, reproduction, and
distribution of this article in any medium by providing adequate credit to the
author(s) and the source of publication.
Funding: None.
Competing interests: The author declares no competing interests.
Author details: Dr. Shem Unger is an associate professor of Biology at Wingate University. He researches amphibian and reptile conservation and conducts research on the Eastern Hellbender Salamander.
Acknowledgements: I thank Wingate
University and the Biology Department for allowing me to conduct this research.
Abstract: Amphibians are
facing threats globally which can present challenges to managers seeking to
document declines. Citizen science platforms are emerging as an effective tool
to document presence of species worldwide. However, little is known regarding
the ability to characterize trends of large, fully aquatic easily identifiable
salamander presence on these platforms within North American freshwater
habitats, as a proxy for monitoring threatened species. This manuscript
provides a baseline for the use of iNaturalist
observations to characterize life history and anthropogenic factors associated
with two amphibian species in decline, the Eastern Hellbender Cryptobranchus alleganiensis
and Common mudpuppy Necturus maculosus salamanders. I report on predatory behavior,
percent alive versus dead, and potential impacts of fishing on these
salamanders. Conservation approaches such as those presented in this
communication can provide a method for monitoring species using the power of
citizen science in areas where researchers are managing threatened populations
of amphibians.
Keywords: Amphibian declines,
aquatic conservation, biodiversity, community science, herpetology.
INTRODUCTION
Threats to freshwater
biodiversity can include decreased water quality, habitat degradation, and
microplastic pollution (Ahmed et al. 2022). Moreover, worldwide amphibians are
facing numerous threats, including habitat destruction, fragmentation, emerging
infectious diseases, and synergistic impacts (Green et al. 2020). Salamanders
found in streams may be especially susceptible to environmental changes brought
on by climate change (Lowe 2012). Two large fully aquatic salamanders which
have a wide geographic range and are readily identified, are the Eastern
Hellbender, Cryptobranchus alleganiensis (Daudin, 1803),
and the Common Mudpuppy Necturus maculosus (Rafinesque, 1818). While information is
lacking, mudpuppies may be experiencing declines (Lannoo
et al. 1994; Hoffman et al. 2014), as they are often found in similar habitats
with hellbenders (Nickerson et al. 2002). Purported reasons for mudpuppy
declines include chemical pollution from lampricide and siltation alongside
degraded habitat (Bonin et al. 1995; Matson 2005) and exploitation by
biological supply companies (Holman 2012). Mudpuppies are regularly captured as
bycatch during ice fishing, as they are active during the winter (Lennox et al.
2018). Eastern Hellbender declines are characterized by a lack of recruitment,
with populations primarily comprised of older adults across their historical
geographic range (Wheeler et al. 2003, Keitzer et al.
2013). Therefore, methods are needed which allow for temporal monitoring of
these populations using effective, low costs non-invasive solutions. One
potential solution to this issue is citizen science monitoring.
Citizen science
monitoring via natural history databases has allowed for rare, threatened
species to be documented and shared with the scientific community (Wilson et
al. 2020). Among the many citizen science platforms, iNaturalist
(www.inaturalist.org) is rapidly emerging as a powerful tool to document
species presence, as a popular smartphone application where users upload images
which are later identified by experts (Nugent 2018). Data obtained from citizen
science participants on this platform can provide valuable freely accessible
data, in many cases accurate to the species level (Wittmann et al. 2019). While
this application has been used to assess injury rates of turtles (Seburn et al. 2023) and document invasive reptiles (Mo
& Mo 2022), further work needs to consider how this citizen science data
can contribute to monitoring rare species, their interactions with
recreationalists, and potentially document mortality and even ecological
connections with other species.
In order to test the
potential for iNaturalist as a monitoring tool for
threatened amphibian taxa, I quantified observations for two readily
identifiable aquatic salamanders, the Eastern Hellbender and the Common
Mudpuppy in the United States across their geographic range. The aim of this
study is to determine: i) the overall presence of
observations for each species, ii) any trends for annual increased use of the
application using yearly observations as a proxy alongside seasonal observation
trends, and iii) discuss how this approach can be incorporated into other
conservation studies of threatened taxa by examining life history, ecological
traits, and anthropogenic impacts in observations on this citizen science
platform.
MATERIALS AND METHODS
Obtaining observation
data
To compile data,
observations were searched within iNaturalist, using
the “explore” tab for both “Hellbender Cryptobranchus
alleganiensis” and “Common Mudpuppy Necturus maculosus”
in the United States, then further constrained to only those for wild,
verified, research grade quality (confirmed by at least two agreeing
naturalist). Research grade observations entail finer taxonomic resolution and
reliable identification (Campbell et al. 2023). I also constrained search to
only include observations up to 31 December 2023 so as not to bias annual
observations. Observations were then exported for collection of state data,
annual increase, monthly observations, and notes on individual specimens. All
observations were downloaded on 20 January 2024. Moreover, each observation
image was visually examined by author between 20 January 2024 and 31 January
2024, and manually processed for number of live versus dead, documentation of any
behaviors, and life history stage (adult versus juvenile). Observation images
were further assessed for species accuracy, as these two species are readily
identifiable with adult hellbenders possessing dorsally flattened bodies,
overall large size and reduced eyes, while adult mudpuppies possessing large
feathery external gills, small limbs, and flattened tail (Petranka
1998). Moreover, larval hellbenders are robust with similar morphologies, while
mudpuppy larvae often possess distinct dorsal dark lines bordered by yellow
stripes (Conant & Collins 1998). Observations that included information on
fishing were also noted. For quantification of juvenile, overall body size was
assessed in image and if larvae or eggs were present, the observation was counted
as ‘juvenile’. Data from downloaded observation was sorted in excel and
primarily descriptive statistics are reported.
RESULTS
In total I documented
260 total observations for Eastern Hellbenders and 457 for Common Mudpuppy
which met search requirements on the iNaturalist
platform. All post included images that were readily identifiable to species
level for both hellbenders and mudpuppies. Observations for hellbenders were
from ten total states, while observations for mudpuppies were across 20 states,
all within their historical geographic range. The top three states with
observations for mudpuppies were Pennsylvania, New York, and Michigan, whereas
for hellbenders was North Carolina, Pennsylvania, and Tennessee. The percentage
of alive and dead individuals was similar for both species, 87.7% & 12.3%
and 97.7% & 2.3%, respectively for mudpuppies and hellbenders (Table 1).
All mortalities (‘dead’) observations for hellbenders were of adults, whereas
for mudpuppies only one juvenile was characterized as ‘dead’ with all remaining
mortalities comprised of adults. Moreover, the percentage of adult versus
juvenile was 79.4% & 20.6% and 90.4% & 9.6%, for mudpuppies and
hellbenders, respectively. All observations of hellbenders included only one
individual in image, whereas for common mudpuppy, there were 444 observations
with one individual, 10 observations with two individuals, and one each for
three, four, and nine individuals in an observation image.
Several instances of
observations including text mention of individuals being captured by fisherman
were included with representative examples as “Hooked this hellbender in the
tail while fly fishing”, “hooked by fisherman”, and “caught on
rod and reel” “caught on hook” ,“angler caught on nightcrawler”,
“a fisherman had caught and killed this poor mudpuppy while powerlining”, and “killed by fisherman”. In at
least one observation for mudpuppies, there was mention of “found while
netting for minnows, released unharmed” and for one with hellbender as “it
was caught in a fishing line, it survived” which implied release of
individual following observer encounter. Instances of predation on mudpuppy
included several observations of mink predations (4), seagulls (2), and a water
snake (1) predating on live adults (Image 1). In addition, there was one
incidence of an observation of a dead mudpuppy regurgitated from a water snake.
There were no observations for predation on hellbenders. The number of images
including eggs was six for both mudpuppies and hellbenders. Four observations
of mudpuppies and three for hellbenders included only the skeletal remains
(Image 2), yet was readily identifiable as species
based on unique morphology.
The number of annual
observations for both mudpuppies and hellbenders generally increased over time
(Figure 1). As the iNaturalist platform came into
existence in 2008, there were still retrospective posts from 2000 till 2008,
which include previous observations prior to the posting date for several
observations. In addition, there was a distinct decrease in the number of
annual observations for both species from 2020 to 2022, likely due to the
Covid-19 lockdown. The months in which the greatest number of observations were
documented was April (70), July (54), and March (53) for mudpuppies, and July
(54), August (47), and September (45) for hellbenders. For hellbenders these
three observation months account for 56.1% of all observations. Therefore, when
these observations are combined, iNaturalist provided
a successful tool to investigate natural history, presence, predation,
mortality, and anthropogenic issues associated both species of large fully
aquatic amphibians.
DISCUSSION
This communication
provides evidence of utilizing the citizen scientists
platform iNaturalist to document presence of
declining salamanders species across their home range alongside observations
which are of interest to conservation managers, including fishing and
documentation of predation events involving these large fully aquatic
salamanders. Interestingly, the use of iNaturalist
observations to obtain data reveals that this platform may provide similar
results for other declining herpetofauna, and other taxa (e.g., mammals, birds,
fish) to detect potential exploitation or human-wildlife interactions.
Historically, the Eastern Hellbender has been harvested and exploited in some
cases large numbers killed (Nickerson & Briggler
2007), largely due to the false beliefs that it is either venomous or consumes
all the fish. However, engaging trout anglers via outreach education
programming has been found to increase reporting of observations to state
agencies responsible for managing eastern hellbenders (Williams et al. 2019).
While several observations included images which show
either mudpuppy or hellbender in a fishing net, it is unclear for many
observations which were mortalities what the exact cause of death was for a
specific individual.
The months in which
observations were highest for both species could be explained by times in which
natural aquatic areas are frequented by recreationalists or anglers frequenting
natural areas. Interestingly, the months with the greatest number of
observations for hellbenders includes a portion of their breeding season, when
individuals are known to be active (Nickerson & Mays 1973) and are likely
readily visible in shallow clear streams. Interestingly, the number of
observations increased annually over time for both species, indicating the
potential for this method of monitoring to provide managers with data on
locations as a complement to more traditional surveys or even more recent
non-invasive techniques in aquatic environments, i.e., eDNA and underwater
camera surveys. However, it is important to note that this increase in annual
observations likely does not reflect an actual on ground population increase
for these salamanders, but just a change in likely frequency of posts or usage
of the iNaturalist application. Subsequently, further
research in population estimation which incorporates mark-recapture studies
should be more reflective of actual status and population trends of these two
enigmatic aquatic salamanders.
Future biodiversity
studies should investigate threatened taxa across conservation status and
taxonomic groupings in other geographic regions using this citizen science
platform. This study demonstrates the potential of iNaturalist
to provide a monitoring tool for threatened species and should be applied to
other threatened taxa. Species which are readily identifiable based on
morphology should be further studied for their presence on this citizen science
platform, as it is vital for citizen science collected data to be accurately
verified if it to be used for research. Subsequently, it is important for
researchers to only include species that are research grade or species for
which morphology can be utilized for reliable identification. It is also
important to only use images where animals are clearly visible
and identification is further validated by researchers or taxonomic experts.
Given the large number of threats facing freshwater fauna, obtaining data using
this method can provide a metric for threatened species presence while
identifying conservation priorities. For example, while some rare species found
in other areas of the world present challenges for surveying, researchers
should consider scanning iNaturalist observations for
their species and geographic region of choice. As I noted both species being captured
by anglers, future outreach should incorporate the impact of fishing on these
large fully aquatic salamanders in decline. Moreover, iNaturalist
observations are concentrated in North America, with fewer observations in
Africa, central America, and southeastern Asia (Di Cecco
et al. 2021). Subsequently, it is possible that in some geographic areas, this
application may not have as many observations as others, outreach science
programs where researchers encourage local communities to record observations
on their phones can add value to rare species surveys. I anticipate the use of
this smartphone application will continue to increase in its use, it may indeed
provide a tool for future monitoring of threatened taxa.
Table 1.
Observation data from iNaturalist for the Common
Mudpuppy, Necturus maculosus
and the Eastern Hellbender, Cryptobranchus alleganiensis. Ad—adult | Juv—Juvenile
| A—alive | D—dead.
|
|
Common Mudpuppy |
Eastern Hellbender |
|
% Life Stage |
Ad:79.4%, Juv: 20.6% |
Ad: 90.4%, Juv: 9.6% |
|
% Alive/Dead |
A: 87.7%, D:12.3% |
A: 97.%, D: 2.3% |
|
Representative
textual observations |
“angler caught
on nightcrawler”, “ a fisherman had
caught and killed this poor mudpuppy while powerlining”,
“regurgitated from a water snake”, “being eaten by a water snake”,
“killed by fisherman”, “caught on hook”, “caught on rod and
reel”. |
“it was caught
in a fishing line, it survived”, “nest with male guarding”, “hooked
by fisherman”, “hooked this hellbender in the tail while fly fishing”,
“specimen was deceased. A rock crushed his shoulder and front leg. It was
given to the NC Wildlife Resources Biologist”. |
For
figure & images - - click here for full PDF
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