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Rapid Expansion of Banded Killifish Fundulus diaphanus across Northern Illinois: Dramatic Recovery or Invasive Species?

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The distribution of the Illinois state-threatened Banded Killifish Fundulus diaphanus has remained largely unchanged in Illinois from 1880 to 2000, being restricted mainly to the northeastern corner of the state. One population identified as Western Banded Killifish F. d. menona has remained stable in the glacial lakes region along the southeastern Wisconsin-northeastern Illinois border. Starting in 2001 a second population began to spread and become more common along the Lake Michigan shoreline. From there the population expanded through the Chicago Area Waterway System into the Des Plaines River and eventually the Illinois River. Historical museum specimens from this region are identified as F. d. menona, but recent specimens are identified as hybrids between F. d. menona and Eastern Banded Killifish F. d. diaphanus. Subsequently, a third population appeared in the Mississippi River near the mouth of the Rock River in 2009 and has spread from there. These individuals are also identified as F. d. menona. The rapid expansion of Banded Killifish from Lake Michigan to the Illinois River appears to be an invasion of the Eastern subspecies F. d. diaphanus and the subsequent hybridization with the native Western subspecies. It is unknown where the Banded Killifish in the Mississippi River originated, possibly from populations 160+ kilometers upstream or human introductions. As the Illinois River and Mississippi River populations continue to expand their ranges, their ecological impacts are unknown at this time.
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Rapid Expansion of Banded Killifish Fundulus
diaphanus across Northern Illinois: Dramatic
Recovery or Invasive Species?
Author(s): Philip W. Willink, Tristan A. Widloe, Victor J. Santucci
Jr., Daniel Makauskas, Jeremy S. Tiemann, Samantha D. Hertel, ,
James T. Lamer, and Joshua L. Sherwood
Source: The American Midland Naturalist, 179(2):179-190.
Published By: University of Notre Dame
https://doi.org/10.1674/0003-0031-179.2.179
URL: http://www.bioone.org/doi/full/10.1674/0003-0031-179.2.179
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Am. Midl. Nat. (2018) 179:179–190
Rapid Expansion of Banded Killifish Fundulus diaphanus
across Northern Illinois: Dramatic Recovery or Invasive
Species?
Philip W. Willink
1
Daniel P. Haerther Center for Conservation and Research, Shedd Aquarium, 1200 South Lake Shore Drive,
Chicago, Illinois 60605
Tristan A. Widloe
2
Aquatic Nuisance Species Program, Illinois Department of Natural Resources, 5931 Fox River Drive, Plano 60545
Victor J. Santucci Jr.
3
and Daniel Makauskas
4
Lake Michigan Program, Illinois Department of Natural Resources, 9511 West Harrison Street, Des Plaines 60016
Jeremy S. Tiemann
5
Illinois Natural History Survey, Prairie Research Institute, University of Illinois at Urbana-Champaign, 1816
South Oak Street, Champaign 61820
Samantha D. Hertel
6
Loyola University Chicago, Department of Biology, 1032 West Sheridan Road, Chicago, Illinois 60626
Daniel P. Haerther Center for Conservation and Research, Shedd Aquarium, 1200 South Lake Shore Drive,
Chicago, Illinois 60605
James T. Lamer
7
Department of Biological Sciences, Western Illinois University, 372 Waggoner Hall, 1 University Circle, Macomb
61455
AND
Joshua L. Sherwood
8
Illinois Natural History Survey, Prairie Research Institute, University of Illinois at Urbana-Champaign, 1816
South Oak Street, Champaign 61820
ABSTRACT.—The distribution of the Illinois state-threatened Banded Killifish Fundulus
diaphanus has remained largely unchanged in Illinois from 1880 to 2000, being restricted
mainly to the northeastern corner of the state. One population identified as Western Banded
Killifish F. d. menona has remained stable in the glacial lakes region along the southeastern
Wisconsin–northeastern Illinois border. Starting in 2001 a second population began to spread
and become more common along the Lake Michigan shoreline. From there the population
expanded through the Chicago Area Waterway System into the Des Plaines River and eventually
1
Corresponding author: e-mail: pwillink@sheddaquarium.org
2
e-mail: Tristan.Widloe@illinois.gov
3
e-mail: Vic.Santucci@illinois.gov
4
e-mail: Dan.Makauskas@illinois.gov
5
e-mail: jtiemann@illinois.edu
6
e-mail: shertel@luc.edu
7
e-mail: jt-lamer@wiu.edu
8
e-mail: jsherwo2@illinois.edu
179
the Illinois River. Historical museum specimens from this region are identified as F. d. menona,
but recent specimens are identified as hybrids between F. d. menona and Eastern Banded
Killifish F. d. diaphanus. Subsequently, a third population appeared in the Mississippi River near
the mouth of the Rock River in 2009 and has spread from there. These individuals are also
identified as F. d. menona. The rapid expansion of Banded Killifish from Lake Michigan to the
Illinois River appears to be an invasion of the Eastern subspecies F. d. diaphanus and the
subsequent hybridization with the native Western subspecies. It is unknown where the Banded
Killifish in the Mississippi River originated, possibly from populations 160þkilometers upstream
or human introductions. As the Illinois River and Mississippi River populations continue to
expand their ranges, their ecological impacts are unknown at this time.
INTRODUCTION
Rapid changes in a species’ distribution involving the increasing range of an invasive
species (e.g., Irons et al., 2006; Kolar et al., 2007) or the decreasing range of a sensitive species
(Metzke et al., 2012) are known to occur. Far less common is the increasing range of a
sensitive species, especially when there is no known intentional stocking or translocation by
natural resource agencies. Un-aided range expansion of sensitive species raises the hope that
perhaps they are responding to improvements in environmental quality. If this is indeed the
case, then there is great interest in attempting similar environmental improvements
elsewhere to expand the ranges of these sensitive species even further. A situation like this is
currently developing in the state of Illinois where Banded Killifish Fundulus diaphanus have
been listed as state-threatened since 1989 (Mankowski, 2012).
The species as a whole is considered secure over its entire range, which extends from the
Dakotas eastward through the Great Lakes to Newfoundland, and then south along the Atlantic
coast to South Carolina (Scott and Crossman, 1973; Page and Burr, 2011). The eastern half of
the range is generally considered to be inhabited by the subspecies Eastern Banded Killifish
Fundulus diaphanus diaphanus, whereas the western half is inhabited by the subspecies Western
Banded Killifish Fundulus diaphanus menona (Hubbs and Lagler, 1947; based on Shapiro, 1947).
Genetic divergence between the two subspecies, according to mitochondrial D-Loop, is 2% and
dates the split between subspecies to approximately 570,000 y ago (April and Turgeon, 2006).
Introgression between the two subspecies is known (April and Turgeon, 2006), as well as
hybridization with other species, such as the Mummichog Fundulus heteroclitus (Weed, 1921;
Hubbs et al., 1943; Griffith, 1968, 1972; Fritz and Garside, 1974; Dawley, 1992; Dawley et al.,
1999, 2000; Herna´ndez Cha´vez and Turgeon, 2007; M´erette et al., 2009).
Illinois is along the southern edge of the Western Banded Killifish range, with historical
records primarily in northeast Illinois and two in the center of the state (Forbes and
Richardson, 1919, 1920; Smith, 1979). Fish biologists in recent years are collecting more
Banded Killifish and from locations where they have not previously been recorded. The
goals of this manuscript are to (1) document changes in the distribution of Banded Killifish
in Illinois from 1880 to the present and (2) assess reasons that may be driving these
distributional changes. This information is critical for the successful management of Banded
Killifish that is designated a Species in Greatest Conservation Need (e.g., state-threatened)
and whose recovery is a goal of the Illinois Wildlife Action Plan (Illinois Department of
Natural Resources, 2016).
MATERIALS AND METHODS
Locality data were based primarily on vouchered specimens in fish collections at The Field
Museum (FMNH), Chicago and the Illinois Natural History Survey (INHS), Champaign
THE AMERICAN MIDLAND NATURALIST180 179(2)
[museum acronyms based on Sabaj (2016)]. Included with these records were significant
amounts of field observation data from the Illinois Department of Natural Resources–
Aquatic Nuisance Species Program conducting surveys in Illinois rivers. The Illinois
Department of Natural Resources–Lake Michigan Program provided field observation data
from five annual beach surveys (south to north; Jackson–Outer Harbor, Farwell Avenue,
Tower Road, Waukegan, and North Point) starting in 1979. Supplemental data included
personal observations from several of the authors and colleagues, as well as literature records
that are considered reliable (e.g., Meek and Hildebrand, 1910; Rivera et al., 2013; Tiemann et
al., 2015; Hrabik, 2016; Lamer et al., 2016; Schmidt, 2016).
These types of data are considered ‘presence only’ and do not explicitly take into
consideration absences from locations where Banded Killifish are historically known to occur.
However, some of the data sources, such as the Illinois Department of Natural Resources–Lake
Michigan Program annual beach surveys and the Long-Term Illinois River Fish Population
Monitoring Program (also known as Long Term Electrofishing), do include repeated surveys
at the same sites over long time periods. In other instances there are examples of areas that
were the focus of short-term intensive surveys, such as Will County (Willink and Veraldi, 2009)
and Lake Calumet (Greenfield and Rogner, 1984). Survey methods, effort, and reporting have
also changed over the past 130þy. There will always be gaps in our understanding, but based
on the considerable number of fish surveys that have been conducted in Illinois, we believe
the general changes in distribution patterns of Banded Killifish in Illinois are real and not
simply artifacts of sampling error, changes in methodology, or increased sampling effort.
Because fish survey methods have changed considerably over the years, it was not possible to
determine a standardized catch per unit effort with this data.
Identification of preserved specimens in the collections of the FMNH and INHS was based
on lateral row scales, which were counted according to Hubbs and Lagler (1947). Although
the character is variable, it has been demonstrated to be informative over the entire
geographic range of the species (Shapiro, 1947, in Hubbs and Lagler, 1947; April and
Turgeon, 2006; Herna´ndez Cha´vez and Turgeon, 2007). Other characters, such as fin ray
counts and pigmentation, were explored. However, normal fin ray counts between these
subspecies differ on average by one fin ray, with considerable overlap in the range of counts
between them. Pigmentation is difficult due to changes during ontogeny.
Data for specimens identified as the Western subspecies F. d. menona from Minnesota,
Iowa, South Dakota, Illinois, and Indiana were combined because of considerable overlap of
lateral row scale counts among regions. These values were consistent with what has
previously been reported in the literature (Shapiro, 1947, in Hubbs and Lagler, 1947). All
museum specimens examined were collected prior to 1957, well before any purported
changes in distribution patterns.
Specimen data for individuals identified as the Eastern subspecies F. d. diaphanus were
based on specimens from Maine as well as mean lateral row scale values reported from
Herna´ndez Cha´vez and Turgeon (2007). The literature values were included because only a
few museum specimens of F. d. diaphanus were readily available, and Herna´ndez Cha´vez and
Turgeon (2007) corroborated their results with genetic data.
RESULTS
DISTRIBUTION
The distribution of Banded Killifish in Illinois is fairly consistent from 1880–2000 (Fig. 1).
There are two records from the center of the state, but both date to 1880. They have not
2018 181WILLINK ET AL.: DRAMATIC RECOVERY OR INVASIVE SPECIES?
FIG. 1.—Distribution of Banded Killifish Fundulus diaphanus in Illinois divided into two time periods
THE AMERICAN MIDLAND NATURALIST182 179(2)
been reported from the Sangamon watershed since and are considered extirpated (Smith,
1979). The rest of the records are restricted to northeastern Illinois, with population centers
in the glacial lakes region near the Wisconsin border and the Calumet region adjacent to
Indiana (Forbes and Richardson, 1919, 1920; Smith, 1979; Retzer and Batten, 2005; Willink,
2009).
Banded Killifish were common in the mouths of Lake Michigan tributaries in the late
1800s (Nelson, 1876; Jordan, 1878) but disappeared through most of the 20th century
(Smith, 1979). However, they began appearing in standardized Illinois Department of
Natural Resources Lake Michigan Program annual beach surveys in 2001 (Fig. 2). They have
been present ever since and catch rates have increased over time. Locations are scattered
along the entire length of the Lake Michigan shoreline in Illinois (Fig. 1).
Although Banded Killifish were known to occur in the Calumet Region since record
keeping started, this population appeared to increase in this area around 2010. From there
they spread down the Calumet Sag Channel, the Chicago Sanitary and Shipping Canal, the
Des Plaines River, and into the upper Illinois River (Fig. 1). There is no evidence (e.g., from
Illinois Department of Natural Resources routine basin surveys) for Banded Killifish from
the Illinois or lower Des Plaines rivers moving up the Fox or Des Plaines rivers to the glacial
lakes along the Wisconsin border. As a side note, the Forest Preserve District of DuPage
County transplanted Banded Killifish from northern Illinois to a site along the West Branch
of the DuPage River in 2010, but the fish have not been seen since at the site.
The first record for Banded Killifish in the Illinois River was 2006 near Starved Rock State
Park in Utica, LaSalle County (Fig. 1). Around 2010 the population expanded downstream
to the Marshall–Peoria County line. From 2001 to 2010, the average rate of range expansion
of Banded Killifish from Lake Michigan to the Marshall–Peoria County line on the Illinois
River was 25.4 river km/y.
Conversely, the first record for Banded Killifish along the Illinois border of the
Mississippi River was in 2009 in Davenport, Iowa, (John Olson, Ben Hucka, and Jerad
Stricker, Iowa Department of Natural Resources, pers. comm.), which is opposite Rock
FIG. 2.—Relative abundance (mean number of fish/seine haul) of Banded Killifish Fundulus diaphanus
based on beach seine sampling at five locations along the Lake Michigan shoreline in Illinois, 1979–2016
2018 183WILLINK ET AL.: DRAMATIC RECOVERY OR INVASIVE SPECIES?
Island County, Illinois (Fig. 1). Around 2010 the Mississippi River population expanded
downstream and moderately up the Rock River. From 2006 to 2015, the average rate of
expansion down the Mississippi River from Davenport, Iowa to West Alton, Missouri, was
55.1 river km/y.
Subspecies and hybrid identification.—Lateral row scales for Western Banded Killifish,
including specimens from Illinois collected prior to 1957, ranged from 36 to 44, with all but
one value between 38–43 (n ¼62) (Fig. 3). Eastern Banded Killifish had 48–51 lateral row
scales (n ¼7).
Specimens collected in the Calumet Region in 2010 and 2011 had 43 to 46 lateral row
scales, with six of the seven vouchers with either 45 or 46 lateral row scales (n ¼7) (Fig. 3).
These values are intermediate between the Western and Eastern values. Hybrids between
Western Banded Killifish and Eastern Banded Killifish exhibit a similar intermediate
pattern elsewhere (Shapiro, 1947, in Hubbs and Lagler, 1947; April and Turgeon, 2006;
Herna´ndez Cha´vez and Turgeon, 2007); therefore, we are tentatively identifying the recent
Calumet individuals as hybrids between the Western and Eastern subspecies. Specimens
collected in the Calumet Region prior to 1937 had 39–44 lateral row scales with a mean of
42 (n ¼23).
Specimens collected in the Mississippi River proper in 2013 had 39 and 44 lateral row
scales, which identify them as Western Banded Killifish (n ¼2). Specimens collected in Coon
Creek (the most upstream Rock River locality) in 2013 had 42 and 47 lateral row scales (n ¼
2). The individual with 42 scales is consistent with the other Western Banded Killifish
identified from the Mississippi watershed. The individual with 47 lateral row scales is difficult
to identify because it is just below values for Eastern Banded Killifish, and conceivably within
the range of hybrids.
FIG. 3.—Lateral row scales of Banded Killifish Fundulus diaphanus from different regions and different
time periods. Sample sizes are F. d. menona (N ¼62), F. d. diaphanus (N ¼7), Mississippi watershed (N ¼
4), and Calumet Region (N ¼7)
THE AMERICAN MIDLAND NATURALIST184 179(2)
DISCUSSION
Populations in the distribution of Banded Killifish remained unchanged for over a century
(Smith, 1979). Most glacial lakes populations appeared stable, although there may have
been a decline in the Fox Chain O’Lakes, which is a subset of lakes that the Fox River flows
directly through that has been heavily impacted by development. Known populations in
Wolf Lake (Willink, 2009) and Powder Horn Lake (Retzer and Batten, 2005) in the Calumet
Region also have persisted over time.
Banded Killifish abundance increased along the shoreline of Lake Michigan at the
beginning of the 21st century and eventually cascaded down the Illinois River.
Environmentally, the Great Lakes are continually exposed to different conditions and
stressors, with introduced species being a common item of concern. Invasive Zebra Mussels
Dreissena polymorpha and Quagga Mussels Dreissena rostriformis bugensis became established in
the 1980s and 1990s (Nalepa et al., 2001), filtering plankton from the water column,
therefore increasing water clarity. A consequence of increased water clarity is increased
macrophyte growth. This benefits Banded Killifish because they use vegetation to spawn
(Richardson, 1939). Concordant with the increase in mussel numbers was a decrease in
invasive Alewife Alosa pseudoharengus (Bunnell et al., 2015; Warner et al., 2015), which are
known to have negative impacts on numerous Lake Michigan fish species via predation on
larvae and smaller individuals (Madenjian et al., 2008).
Physical aspects of Lake Michigan are shifting as well. Water temperature, for example, is
increasing with climate change, with a particularly large jump of about 2.5 C during the
1997–1998 El Ni˜
no event (Gronewold and Stow, 2014). Pollution is on the decline [e.g.,
drops in PCB levels in salmon (Rasmussen et al., 2014)] attributable to decades of increased
environmental regulations, although pollution is certainly still present in the region.
Similarly, the upper Illinois River was so heavily polluted it became devoid of freshwater
mussels (Starrett, 1971). However, after the passage of the Clean Water Act, conditions
improved and mussels recolonized the area (Sietman et al., 2001).
As to whether any of these biological or environmental factors, an unknown factor(s), or
combination of factors played a role in the expansion of Banded Killifish in Illinois is
unclear. Several could have improved environmental conditions for Banded Killifish and
facilitated population increases, even if they were not the root cause of the increase. One
reason it is difficult to determine which factors may have contributed to the range expansion
is because many of the Banded Killifish in Illinois today do not appear to be the same
subspecies of Banded Killifish present in Illinois in the past.
Prior to 1989 Banded Killifish in Illinois appeared to belong to the Western subspecies.
Recent records (1989–today) are sparse because it is listed as state-threatened in Illinois,
hence collection of vouchers is strongly discouraged and regulated by permits. The few
specimens that have been preserved recently in museum collections have lateral row scale
counts intermediate between the Western subspecies and the Eastern subspecies. This is a
common introgression pattern among fishes, with hybrids often intermediate between the
two parent species (Hubbs, 1955).
Hybrids have been documented between Banded Killifish subspecies. Hubbs and Lagler
(1947) based on data from Shapiro (1947) reported an intergrade zone between the two
subspecies in Lake Ontario and the St. Lawrence River. The thought was the subspecies
occupied separate refugia during the last glaciation, with the Eastern subspecies occupying
an area along the Atlantic coast and the Western subspecies in the Mississippi River (Bailey
and Smith, 1981). As the glaciers retreated, each subspecies expanded their respective
ranges until they made secondary contact and introgressed. Genetic patterns among Banded
2018 185WILLINK ET AL.: DRAMATIC RECOVERY OR INVASIVE SPECIES?
Killifish populations along the St. Lawrence are consistent with this history (Rey and
Turgeon, 2007). This theory was validated by April and Turgeon (2006) who analyzed
genetics and morphology. However, they found the ‘hybrid zone’ to extend into Ohio along
Lake Erie, farther than people realized. The western edge of this ‘hybrid zone’ was identified
by mitochondrial DNA from the Eastern subspecies introgressing into the Western
subspecies. Farther east, the morphology and nuclear DNA were intermediate between
parent subspecies.
Part of the explanation for the biogeographic patterns evident in Illinois today may be
that Eastern Banded Killifish or hybrids somehow made it to southern Lake Michigan and
spread from there. This is consistent with identifications based on lateral row scales and the
westward expansion pattern documented by April and Turgeon (2006) in the eastern Great
Lakes. As to why these killifish are expanding their range now, when the Western Banded
Killifish previously present in Illinois did not, is unclear. Trautman (1981) reported Eastern
Banded Killifish appeared to be more tolerant of pollution and were not as reliant on
vegetation for spawning; therefore, it may be that they are better suited to the prevalent
habitats in the region than are the original Western Banded Killifish. The native range of
Eastern Banded Killifish also extends farther south than that of the Western Banded
Killifish. It may be that increasing water temperatures due to climate change are also
benefiting these hybrids if Eastern Banded Killifish tolerances are expressed (Hayhoe et al.,
2010; Gronewold and Stow, 2014).
These scenarios may explain the increase in the Lake Michigan-Illinois River population
and the relative stasis of the glacial lakes population, but they do not explain the appearance
and subsequent expansion of the Mississippi River population. There were pre-existing
Banded Killifish populations in the Mississippi watershed, notably central Wisconsin,
Minnesota, and northwestern Iowa (Becker, 1983; Page and Burr, 2011). Each of these is
160þkm away from the Illinois records in the Mississippi. The largest Illinois population
appears to be in Pool 19. This impoundment is heavily vegetated with very low flow (Tazik et
al., 1993), acting more like a lake than a river. This is consistent with the habitat preferences
of the species. Although, it is possible there was a downstream colonization event from
Wisconsin, Minnesota, or Iowa, perhaps associated with recent flooding, we have no
intervening records between these upstream populations and the recent Illinois population
to support this scenario.
There is an aquatic connection between the Illinois River watershed and the Mississippi
watershed via the Hennepin Canal. However, the canal has been defunct for years and it
would have been difficult for the fishes to move through the multiple closed locks.
Furthermore, the Lake Michigan–Illinois River individuals are putative hybrids, whereas
most of the Mississippi River individuals appear to be Western Banded Killifish.
Another possible explanation for the Mississippi River population is an accidental or
intentional release by someone. There are documented occurrences of people moving
killifish between waterbodies [e.g., western Pennsylvania (Raney, 1938) and in
Newfoundland (Mitchell and Purchase, 2014)] but no specific evidence surrounding this
possibility for Banded Killifish in the Midwest.
There is still a considerable amount of ambiguity surrounding this rapidly changing range
of Banded Killifish in Illinois. Genetic data are required to develop a clearer picture. Due to
the potential for directional introgression, mitochondrial and nuclear markers would be
necessary. It would even be beneficial to incorporate microsatellites to analyze finer
biogeographic patterns within this rapid range expansion, as well as to determine potential
source populations.
THE AMERICAN MIDLAND NATURALIST186 179(2)
Nonetheless, there are already important management implications based on the findings
reported in this publication. First, in Illinois the listing of a species as state-threatened or
state-endangered is decided at the species level. Subspecies are not considered as separate
taxonomic units. Hence it does not matter if the Banded Killifish in Illinois are of the
Western subspecies, Eastern subspecies, or hybrids. They are all considered equally in
determining listing status.
Second, there appear to be at least three management units, each with its particular
history, requirements, and potential future trajectories. One is the Lake Michigan to Illinois
River population that is made up of putative hybrids. This population could conceivably be
divided into sub-populations (e.g., Illinois River, Lake Michigan, etc.). The second is the
recent Mississippi River population that continues to expand. The third is the glacial lakes
population. There is no indication the rapid expansion occurring elsewhere in the state has
reached this region along the Wisconsin border. Expansion here would require movement
of fish past dams in the Fox and Des Plaines rivers, as well as their tributaries. Additionally,
the connections that occurred between glacial lakes and streams of this area have been
disrupted due to development. For the time being, this area appears to be isolated and may
be the last remaining original stock of Western Banded Killifish in the state.
One implication of there being different Banded Killifish management units involves
stocking considerations. There have been two recent introductions of Banded Killifish
authorized by the Illinois Department of Natural Resources–Prairie Crossing in 1998 and the
West Branch DuPage River in 2010 mentioned above. Each involved stock populations from
glacial lakes, and both of the introduced populations were close to the source populations in
northeast Illinois. The Prairie Crossing appears to have worked (Schaeffer et al., 2012; Bland,
2013), whereas there is no evidence to date that the West Branch DuPage River has worked.
In regards to future translocations and to preserve original genetics, there needs to be
increased scrutiny regarding source populations and stocking locations.
A third management issue is the potential ecological impacts, especially in areas where
Banded Killifish had not been found in the past. For example further expansion throughout
the Mississippi River system could potentially lead to ‘‘unnatural’’ competitive pressures on
species that have not encountered this killifish before. Close monitoring of the expansion is
needed.
Determining whether the range expansion represents dramatic recovery or an invasive
species is more complicated than originally realized, and it depends upon the taxonomic
level used to address the question. At the species level, Banded Killifish as a whole was stable
in Illinois, possibly declining slowly, until recent events. From that perspective this is a
dramatic recovery. At the subspecies level, if Illinois is on the forefront of the westward
expansion of the Eastern Banded Killifish, then it could be considered an invasion, as there
are no historical records for Banded Killifish for the Illinois portion of the Mississippi River.
This could also be considered an invasion if human intervention is involved, even though
this population appears to be from regional stock.
Given current trends, Banded Killifish may continue to expand its range. This expansion
could incorporate other states in the region, most notably Indiana, Wisconsin, Iowa, and
Missouri. A larger regional view will be needed to determine where the various taxonomic
subunits originated and where they may be spreading. Although Banded Killifish historically
split into two subspecies that were for a while evolving along their own independent
trajectories to potentially becoming full distinct species in the future, they may now be
gradually recombining back into a single species whose distribution could be continuing to
expand.
2018 187WILLINK ET AL.: DRAMATIC RECOVERY OR INVASIVE SPECIES?
Acknowledgments.—Access to preserved voucher specimens was granted by Susan Mochel (The Field
Museum), Kevin Swagel (The Field Museum), Caleb McMahan (The Field Museum), Chris Taylor
(Illinois Natural History Survey), and Dan Wylie (Illinois Natural History Survey). Significant amounts of
locality data were also provided by many staff associated with the Illinois Department of Natural
Resources–Aquatic Nuisance Species Program and Lake Michigan Program annual beach surveys. Brian
Zimmerman (Ohio State University–Museum of Biological Diversity) raised the potential that Eastern
Banded Killifish could be in Illinois. Charles Knapp (Shedd Aquarium) and Rebecca Gericke (Shedd
Aquarium) provided comments on drafts of the manuscript. Fieldwork was partially supported by Illinois
Department of Natural Resources State Wildlife Grant # T-106-R-1 / United States Fish and Wildlife
Service Grant # F15AF01082 and Shedd Aquarium.
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SUBMITTED 8SEPTEMBER 2017 ACCEPTED 8JANUARY 2018
THE AMERICAN MIDLAND NATURALIST190 179(2)
... However, populations of Western Banded Killifish declined throughout the twentieth century (Hubbs and Lagler 1958;Smith 1979;Lyons 1989), resulting in the listing of the subspecies as vulnerable in Wisconsin, threatened in Illinois, and endangered in Ohio of the U.S. (Illinois Endangered Species Protection Board 2020; Wisconsin Natural Heritage Program 2016; Ohio Department of Natural Resources 2022). By contrast, Eastern Banded Killifish have been introduced, by unknown mechanisms, from their primarily Atlantic coastal native range inland into the Ohio River and Great Lakes basin (Trautman 1981;Willink et al. 2018;. This subspecies has since spread rapidly throughout Lake Michigan and connected waters including the Illinois and St. ...
... This subspecies has since spread rapidly throughout Lake Michigan and connected waters including the Illinois and St. Joseph rivers (Willink et al. 2018;Happel and Gallagher 2021;. Additionally, Eastern Banded Killifish are taking advantage of habitats in Lake Michigan both nearshore and offshore (Smith and Harris 2020) where Western Banded Killifish did not historically occur. ...
... We collected 60 total primary consumers (30 consumers of pelagic carbon, such as clams and Dreissenid mussels, and 30 consumers of littoral carbon, such as amphipods and snails) as well as 78 total Banded Killifish (36 Eastern and 42 Western subspecies) from three sites in Illinois and three sites in Michigan, U.S., in July and August 2021 for stable isotope and gut content metabarcoding analyses (Table 1). We used allopatric populations of each Banded Killifish subspecies inferred from past genetic sequencing because of uncertainty around the morphological identification of these fish and especially their hybrids (e.g., Willink et al. 2018;. Western Banded Killifish were collected from inland lakes in Michigan-Clear Lake at 94 ha area with a maximum depth of 11 m and a 3.7 m recent Secchi disk depth, Lincoln Lake at 166 ha area with a maximum depth of 20 m and a 2.7 m recent Secchi disk depth, and Rose Lake at 151 ha area with a maximum depth of 9 m and a recent Secchi disk depth of 1.5 m. ...
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Researchers, managers, and policymakers have historically neglected non-game fishes relative to game fishes, and this oversight has extended to invasive non-game fishes in the United States. One such fish—the Eastern Banded Killifish (Fundulus diaphanus diaphanus Lesueur 1817)—has established and rapidly spread in Lake Michigan and connected waters since 2000. Here, we assess potential drivers of the successful invasion of Eastern Banded Killifish, as well as their potential to disrupt native communities and food webs. Specifically, we compare the trophic niche breadth and diet composition between Eastern Banded Killifish and a native subspecies, Western Banded Killifish (Fundulus diaphanus menona Jordan and Copeland 1877), using stable isotope and gut content metabarcoding analyses. Stable isotope analysis showed that Eastern Banded Killifish had a higher variance in littoral dependence and trophic position than Western Banded Killifish, but both stable isotope and gut content metabarcoding analyses revealed an overlap in the diet composition and trophic position between the subspecies. Eastern Banded Killifish may successfully establish outside its native range due to higher feeding variability than Western Banded Killifish, including in habitats historically unused by the native subspecies, but the trophic niche between these two subspecies was similar overall. This study provides insights into the successful invasion of a potentially overlooked non-game fish—Eastern Banded Killifish—while also comparing stable isotope and gut content metabarcoding analyses for an invasive freshwater fish for the first time.
... Initially native to the Atlantic Coast and inland towards Lake Erie ( Figure 1), invasive Eastern Banded Killifish have rapidly spread throughout the historical range of Western Banded Killifish over the last several decades, particularly in Lake Michigan and connected waters Willink et al., 2018). The invasion of Eastern Banded Killifish poses a threat to already imperilled Western Banded Killifish, which declined due to habitat transformation or loss throughout the 20th century in Illinois, United States (US; Smith, 1979) and Wisconsin, United States (Lyons, 1989 (Smith, 1979). ...
... Banded Killifish in Lake Michigan and adjoining waters were introduced from the mid-Atlantic region of the United States , and it appears that these fish were initially introduced around the Chicago Area Waterway System that artificially connects Lake Michigan to the Mississippi River basin (Figure 2;Happel & Gallagher, 2021;Willink et al., 2018). For this study, we used the confluence of the Chicago River and Lake Michigan in Illinois (41.88, −87.61) as the proposed source of the invasion for analyses focused on the spread of Eastern Banded Killifish as related to patterns of admixture and introgression. ...
... For this study, we used the confluence of the Chicago River and Lake Michigan in Illinois (41.88, −87.61) as the proposed source of the invasion for analyses focused on the spread of Eastern Banded Killifish as related to patterns of admixture and introgression. Admixed individuals between Eastern and Western Banded Killifish have previously been documented based on both mitochondrial and nuclear sequences as well as morphological analyses (April & Turgeon, 2006;Willink et al., 2018), but our study is the first to apply next-generation RADseq approaches to investigate the population genomics of these fish. ...
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Hybridisation can be an important driver of evolutionary change, but hybridisation with invasive species can have adverse effects on native biodiversity. While hybridisation has been documented across taxa, there is limited understanding of ecological factors promoting patterns of hybridisation and the spatial distribution of hybrid individuals. We combined the results of ecological niche modelling (ENM) and restriction site-associated DNA sequencing to test theories of niche conservatism and biotic resistance on the success of invasion, admixture, and extent of introgression between native and non-native fishes. We related Maxent predictions of habitat suitability based on the native ranges of invasive Eastern Banded Killifish (Fundulus diaphanus diaphanus Lesueur 1817) and native Western Banded Killifish (Fundulus diaphanus menona Jordan and Copeland 1877) to admixture indices of individual Banded Killifish. We found that Eastern Banded Killifish predominated at sites predicted as suitable from their ENM, consistent with niche conservatism. Admixed individuals were more common as Eastern Banded Killifish habitat suitability declined. We also found that Eastern Banded Killifish were most common at sites closest to the presumed source of this invasion, whereas the proportion of admixed individuals increased with distance from the source of invasion. Lastly, we found little evidence that habitat suitability for Western Banded Killifish provides biotic resistance from either displacement by, or admixture with, invasive Eastern Banded Killifish. Our study demonstrates that ENMs can inform conservation-relevant outcomes between native and invasive taxa while emphasising the importance of protecting isolated Western Banded Killifish populations from invasive conspecifics.
... Following their accidental introduction and establishment, intraspecific hybridization of roo with critically endangered rok (R. o. kurumeus) has been the major contributing factor in the loss of existing rok populations (Onikura et al., 2013). Similarly, a potential intraspecific invasion within banded killifish (Fundulus diaphanus) in Lake Michigan and adjacent waters may have negative implications for a native subspecies of this fish (Willink et al., 2018). ...
... Western banded killifish are now considered Vulnerable in Wisconsin, Threatened in Illinois, and Endangered in Ohio, U.S. (Illinois Endangered Species Protection Board, 2020;Ohio Department of Natural Resources, 2022;Wisconsin Natural Heritage Program, 2021). However, in the early 2000s, the frequency of banded killifish collections began increasing in Lake Michigan and connected waters Willink et al., 2018), including the Des Plaines, Illinois, and Mississippi rivers in Illinois that are artificially connected to Lake Michigan by the Chicago Area Waterway System (Irons et al., 2006;Mills et al., 1993;Pegg, 2002). While originally thought to be western banded killifish recovering in the region, morphological analyses of some individuals suggested that these fish may be eastern banded killifish or hybrids between the two subspecies (Willink et al., 2018). ...
... However, in the early 2000s, the frequency of banded killifish collections began increasing in Lake Michigan and connected waters Willink et al., 2018), including the Des Plaines, Illinois, and Mississippi rivers in Illinois that are artificially connected to Lake Michigan by the Chicago Area Waterway System (Irons et al., 2006;Mills et al., 1993;Pegg, 2002). While originally thought to be western banded killifish recovering in the region, morphological analyses of some individuals suggested that these fish may be eastern banded killifish or hybrids between the two subspecies (Willink et al., 2018). However, the taxonomic assignment of increasingly prevalent banded killifish in Lake Michigan and adjacent waters has not previously been evaluated by molecular approaches (April and Turgeon, 2006). ...
Article
Biological invasions can produce severe ecological impacts at both large spatial scales between distantly related species and also smaller spatial scales between conspecifics. We investigated here a potential intraspecific invasion within Lake Michigan and adjacent waters. Banded killifish (Fundulus diaphanus) experienced population increases and spread into novel habitats over recent decades in this region, but managers and policy makers were uncertain if these fish were native western banded killifish (F. d. menona) or instead an invasion by non-native eastern banded killifish (F. d. diaphanus). We applied mitochondrial DNA (mtDNA) barcoding and population genetic analyses to investigate the identity of these fish. We found that new banded killifish populations were the eastern subspecies, including mtDNA haplotypes from the remote mid-Atlantic region, suggesting some introductions from anthropogenic pathways (e.g., live bait trade) rather than only spread from connected, downstream waters (e.g., Lake Erie). Further, population genetic analyses identified eastern banded killifish in our focal region as having low genetic diversity relative to their native range, and relative to western banded killifish populations. Lastly, we found non-native eastern banded killifish were associated with Lake Michigan and connected waters, rather than isolated kettle lakes, and primarily occurred at clearer sites potentially affected by dreissenid mussel invasions. More research is needed on the causes and consequences of eastern banded killifish invasions in Lake Michigan and adjacent waters, including an emphasis on their risk to the conservation of western banded killifish.
... The species is separated into two subspecies, the Eastern (Fundulus diaphanus diaphanus) and Western (Fundulus diaphanus menona) Banded Killifish (April and Turgeon, 2006). These subspecies are estimated to have split from each other approximately 570,000 y ago and can be distinguished from each other by both morphological and genetic traits (April and Turgeon, 2006;Willink et al., 2018). The Eastern Banded Killifish was historically found from western Lake Erie to the Atlantic coast and is distinguished by a lateral row scale count of 48-51. ...
... Where they overlap hybridization occurs and these fish have lateral row scale counts and morphological traits intermediate between the two subspecies. In southwestern Lake Michigan, which includes Calumet Harbor of Chicago, the native population of Western Banded Killifish was relatively small and stable between the years 1880-2000 (see Fig. 1 in Willink et al., 2018), but in 2001 a dramatic species-level distribution shift began. ...
... Within the last two decades, the Eastern Banded Killifish arrived in Lake Michigan through unknown means, hybridized with Western Banded Killifish, and their offspring began spreading throughout the Chicago Area Waterway System and Illinois River (Tiemann et al., 2015;Willink et al., 2018). The rapid expansion was surprising given Banded Killifish have been listed as a state threatened species in Illinois since 1989. ...
Article
Banded Killifish Fundulus diaphanus are considered a nearshore species closely associated with emergent or submergent vegetation in shallow calm waters. This species is commonly collected in nearshore waters of the Laurentian Great Lakes, usually along margins of coastal wetlands, beaches, drowned river mouth lakes, and slow-moving streams. However, in recent years (2015–2018) Banded Killifish have commonly been collected along the exposed, industrialized nearshore waters of Lake Michigan around the Calumet Harbor area (Chicago, IL). Individual specimens have been collected up to 2.8 km from shore and in depths up to 9.8 m in open waters of Lake Michigan. Capture of this species along hardened shoreline habitat, including rip-rap and steep drop-offs is also highly unusual for this small, littoral species and is not documented in the available literature. These observations provide an extreme example of habitat use by this littoral species and broadens our understanding of their habitat in nearshore waters of the Laurentian Great Lakes.
... River since 2009 (Willink et al. 2018). Recent changes in environmental conditions within the Great Lakes due to introduced species and climate change may have benefited the eastern subspecies in this area, while the western subspecies may have been introduced into the Mississippi River (Willink et al. 2018). ...
... River since 2009 (Willink et al. 2018). Recent changes in environmental conditions within the Great Lakes due to introduced species and climate change may have benefited the eastern subspecies in this area, while the western subspecies may have been introduced into the Mississippi River (Willink et al. 2018). ...
Article
Full-text available
Newfoundland’s Banded Killifish (Fundulus diaphanus) population is listed as a species of Special Concern under Canada’s Species at Risk Act and Vulnerable under Newfoundland and Labrador’s Endangered Species Act. Mummichog (Fundulus heteroclitus) is a similar looking fish species and is currently under review by Newfoundland and Labrador’s Species Status Advisory Committee. Both species have limited known distributions in Newfoundland waters that overlap. They may occur sympatrically in estuaries and occasionally hybridize; thus, field identifications can be challenging. We found that dorsal fin position and caudal fin depth were the most useful morphological characters for distinguishing Banded Killifish and Mummichog in the field. We used local ecological knowledge, literature review, museum records, and field surveys to update the known distribution ranges and found both species in more locations than previously documented in Newfoundland. Thus, we extend their known ranges. Our results will be critical in future status assessments of these species in Newfoundland.
... diaphanus menona) and Eastern (F. diaphanus diaphanus) subspecies of Banded Killifish occur in the area and appear to readily hybridize (Willink et al. 2018). It has been suggested that Eastern Banded Killifish populations have migrated from Lake Michigan into the CAWS system as several Banded Killifish of unknown subspecies appeared in seine surveys of Illinois beaches in 2001 (Willink et al. 2018). ...
... diaphanus diaphanus) subspecies of Banded Killifish occur in the area and appear to readily hybridize (Willink et al. 2018). It has been suggested that Eastern Banded Killifish populations have migrated from Lake Michigan into the CAWS system as several Banded Killifish of unknown subspecies appeared in seine surveys of Illinois beaches in 2001 (Willink et al. 2018). Banded Killifish first appeared in the CAWS in 2010 at SEPA station 1, near our Calumet River location, at which they did not appear until 2012, and were later found in other parts of the CAWS. ...
Article
Full-text available
How fish assemblages change over time in highly-modified urban rivers, where physical and chemical properties rarely mimic non-urban systems, has sparsely been documented. Data have been collected on fishes within the boundaries of the Chicago Metropolitan area routinely since the mid-1980's. Representing fish assemblages in one of the largest cities of America, this dataset offers the ability to investigate and track changes in assemblage composition in an urbanized river. To this end, multi-variate modelling, as well as various visualization techniques, were used to assess and describe compositional changes in the fish assemblage of Chicago's waterways. In general, there were gradual enhancements in the fish assemblages of Chicago's waterways throughout the years studied, which are characterized by more fish, of which more are native species. Small-bodied native fishes (Cyprinidae), game fishes (Centrarchidae), as well as catfish (Ictaluridae) have increased in relative abundance, whereas several invasive fish species exhibited declines. Exponential growth of Banded Killifish (Fundulus diaphanous) relative abundance appears to continue from previously noted range expansions. As Chicago and other cities move towards supporting fishable waterways, interest may lay in investigating population vital rates and habitat or water quality factors affecting them in heavily urbanized settings.
... For example, the Chicago Area Waterway System (CAWS), an artificial waterway system located in the greater Chicagoland area, has created an unnatural connection between the Mississippi River drainage to the Laurentian Great Lakes basin and allows unabated spread of nonindigenous animals. Species such as D. polymorpha, Round Goby Neogobius melanostomus (Pallas, 1814), and Eastern Banded Killifish Fundulus diaphanus diaphanus (LeSueur, 1817), have spread from Lake Michigan, through the CAWS, and into the Illinois River-Mississippi River drainage (Mills et al. 1993;Pegg 2002;Irons et al. 2006;Willink et al. 2018). Other species, such as Corbicula spp., Bighead Carp Hypophthalmichthys nobilis (Richardson, 1845), Silver Carp Hypophthalmichthys molitrix (Valenciennes, 1844), and Black Carp Mylopharyngodon piceus (Richardson, 1845), have dispersed up the Mississippi River and threaten the Laurentian Great Lakes (Laird and Page 1996;Irons et al. 2009;Douglass et al. 2020). ...
Article
Full-text available
Nonindigenous aquatic species (NAS), some of which are referred to as aquatic invasive species (AIS) or non-native aquatic species, are those aquatic organisms that have become established beyond their native ranges. They often inhabit a variety of habitats and physicochemical conditions, reach high densities, and alter ecosystem function. Understanding the distribution of nonindigenous aquatic species is vital to protecting native biodiversity in invaded ecosystems. A search of museum collections, literature accounts, and field surveys conducted in recent years by biologists from the Illinois Natural History Survey, Illinois Department of Natural Resources, and other agencies revealed 13 nonindigenous aquatic mollusk species reported to occur in Illinois. Ten species (five bivalves and five gastropods) have viable reproducing populations. One species, the Big-eared Radix Radix auricularia (Linnaeus, 1758), is no longer extant in Illinois, and two species, the European Stream Valvata Valvata piscinalis (Müller, 1774) and European Fingernail Clam Sphaerium corneum (Linnaeus, 1758), have an unknown status. Some species, such as the Basket Clam Corbicula fluminea (Müller, 1774), Zebra Mussel Dreissena polymorpha (Pallas, 1771), and Chinese Mysterysnail Cipangopaludina chinensis (Gray in Griffith and Pidgeon, 1833), are widespread and abundant. However, other species like the Mottled Fingernail Clam Eupera cubensis (Prime, 1865) and New Zealand Mudsnail Potamopyrgus antipodarum (Gray, 1843) are currently restricted to a particular location or drainage. Other nonindigenous aquatic mollusks with the potential for becoming established in Illinois or border waters are also discussed.
... Given the extensive conventional sampling of both lakes, it is unlikely that the detections are from DNA shed from individuals residing in each waterbody. In certain cases, such as the detection of F. diaphanus in Lake Wingra, it is possible that F. diaphanus recently recolonized the lake and is a true detection (Willink et al., 2018). Unfortunately, it is very difficult conclusively say whether detections are false-positives due to contamination, misassignment, or from DNA that originated from adjacent unsampled streams or wetlands or transferred to the lake by some other means. ...
Article
Full-text available
Aim To evaluate the ability of precipitation‐based environmental DNA (eDNA) sample collection and mitochondrial 12S metabarcoding sequencing to reconstruct well‐studied fish communities in lakes and rivers. Specific objectives were to 1) determine correlations between eDNA species detections and known community composition based on conventional field sampling, 2) compare efficiency of eDNA to detect fish biodiversity among systems with variable morphologies and trophic states, and 3) determine if species habitat preferences predict eDNA detection. Location Upper Great Lakes Region, North America. Methods Fish community composition was estimated for seven lakes and two Mississippi River navigation pools using sequence data from the mitochondrial 12S gene amplified from 10 to 50 water samples per waterbody collected in 50‐mL centrifuge tubes at a single time point. Environmental DNA (eDNA) was concentrated without filtration by centrifuging samples to reduce per‐sample handling time. Taxonomic detections from eDNA were compared to established community monitoring databases containing up to 40 years of sampling and a detailed habitat/substrate preference matrix to identify patterns of bias. Results Mitochondrial 12S gene metabarcoding detected 15%–47% of the known species at each waterbody and 30%–76% of known genera. Non‐metric multidimensional scaling (NMDS) assessment of the community structure indicated that eDNA‐detected communities grouped in a similar pattern as known communities. Discriminant analysis of principal components indicated that there was a high degree of overlap in habitat/substrate preference of eDNA‐detected and eDNA‐undetected species suggesting limited habitat bias for eDNA sampling. Main conclusions Large numbers of small volume samples sequenced at the mitochondrial 12S gene can describe the coarse community structure of freshwater systems. However, additional conventional sampling and environmental DNA sampling may be necessary for a complete diversity census.
Article
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Non-native fishes can cause ecological impacts as invasive species, but identifying which non-native species have harmful impacts is critical to prioritizing management and policy responses. Here, we characterized the state of knowledge on the impacts of a possibly overlooked group of invasive species in the United States: non-game native transplant (NGNT) fishes. We propose that NGNT fishes may be understudied relative to non-native game fish and exotic species introduced from outside of the country. Only 14% of 220 freshwater NGNT fishes in the United States have been studied for possible negative impacts. We found that researchers have neglected to study impacts of many widespread NGNT species, and some regions with high NGNT species richness have had no studies of impacts of any of these fishes. Genetic and ecosystem impacts of NGNT fishes have been particularly neglected relative to population and community impacts. We recommend that researchers – and funders – direct attention to prospective impacts of the most widespread NGNT species in the least-studied river basins in the United States to identify which of these fishes require prevention and management as invasive species.
Article
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Fish surveys by university and natural resource agency staff and fish hobbyists in Illinois, and the acquisition of the former Northern Illinois University fish collection by the Illinois Natural History Survey, have documented significant new voucher records for 21 fish species in the state. We herein report on those records.
Article
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While conducting a general survey in a small tributary of the Rock River, two individuals of banded killifish (Fundulus diaphanous) were found. This species was sampled during October, 2012, in Rock Island County, Illinois. The banded killifish may be expanding its range to northwest Illinois.
Article
Partial catalogue of the fishes of Illinois