Geographic Range
Gilt darters are native to North America and can be found from eastern Minnesota to
western New York, south to northern Arkansas, Mississippi, Alabama, and Georgia. Currently,
its geographic range is declining due to erosion, siltation, man-made water obstructions,
and pollution.
Habitat
Gilt darters inhabit relatively clear, freshwater streams and rivers. Inhabited streams
and rivers range from 20 to 100 m wide, with flow rates ranging from 0.5 to 1.2 m/sec,
year round. Gilt darters migrate to different depths depending on season. During spring
and early summer, they spawn in shallow, swift moving riffles and raceways of the
stream. After breeding season, gilt darters reside in the deeper caverns and sediment-free,
gravelly beds where they remain for the rest of the year.
- Habitat Regions
- temperate
- Aquatic Biomes
- rivers and streams
Physical Description
Gilt darters are midsized when compared to other fish in the
darter family
. In general, they are fairly small, measuring about 6.35 cm in length. The dorsal
surface of gilt darters is colored dark olive and the sides and belly are typically
a striking bronze. This stout and compressed fish has five to eight dark bands, depending
upon its age, that run across its back and down its sides. Gilt darters are sexually
dimorphic during breeding season. They have a homocercal caudal fin, and the anterior
dorsal fin has 10 to 13 spines. The membrane between dorsal spines tends to be dark
and the tips of the spines are orange. Similarly the posterior caudal fin has 11 to
13 soft rays; however, this fin is more translucent and colorless. The caudal, anal,
pelvic, and pectoral fins all have orange pigments near their bases, but the majority
of these fins is colorless. The anal fin has approximately 2 spines and 8 to 11 rays
and is colorless.
- Other Physical Features
- ectothermic
- heterothermic
- bilateral symmetry
- Sexual Dimorphism
- sexes colored or patterned differently
- male more colorful
Development
Male gilt darters fertilize the eggs released by the female, resulting in hundreds
of offspring. The eggs measure at 1.1 to 1.4 mm in diameter, and harden when they
come into contact with water. Eggs are yellow to orange in color and hatch in about
8 to 10 days, when water temperatures are approximately 20°C. Larvae measure 4.0 to
4.8 mm long. This stage of their life lasts only lasts about 1 week until they become
juvenile gilt darters.
Reproduction
Gilt darters are polyandrous, as multiple males mate with a single female. When breeding
season ensues, the behavior and appearance of males changes dramatically. The upper
body turns a dark blue-green while the ventral surface becomes an iridescent yellow
or orange. Their sides become blotched with dark pigment, while the bases of each
of its fins become dark blue. Males compete for access to mates by establishing a
breeding territory around cobbles and small rocks in the shallow riffles of its habitat.
They become highly aggressive towards potential rivals. During this time, they frequently
use techniques such as chasing, tail-beating, confident body posturing, and rapid
color change tactics to defend their territory from potential rivals. Conversely,
when a female enters a male's territory, she is promptly pursued. If the female is
interested, she displays attractive body posturing and uses tactile stimulation to
further entice the male. Gilt darters bury their eggs in the gravel or sandy bottoms
of streams that have consistent flow rates. Once the female decides upon a location,
the male and female begin to mate. The male swims next to the female in a head-to-head
position and they begin vigorously quivering while discharging sperm and eggs. While
they are mating, the pair pushes down on the substrate to bury their eggs from potential
harm.
- Mating System
- polyandrous
Gilt darters breed once annually during summer, when water temperatures are 17°C or
warmer. Mature females lay 132 to 762 eggs, with an average of 247 eggs. Eggs take
approximately 8 to 10 days to mature into the larval stage. Time to reproductive maturity
varies with sex. Males reach sexual maturity by 11 to 13 months of age, and females
reach reproductive maturity by 22 to 23 months of age.
- Key Reproductive Features
- iteroparous
- seasonal breeding
- sexual
- fertilization
There is no parental investment in gilt darters besides development, laying, and fertilization of eggs.
- Parental Investment
-
pre-fertilization
- provisioning
-
protecting
- female
Lifespan/Longevity
Wild gilt darters have an average lifespan of 2 to 3 years. Occasionally, some may
live for up to 4 years. It is thought that less than 10% of 1-year old individuals
live to the age of 3. There is no information available regarding the average lifespan
of captive individuals.
Behavior
Compared to other
darters
, gilt darters are highly mobile. They have a small gas bladder that enables them
to have greater mobility and and maneuverability across the entire water column. They
have been observed actively swimming around their habitat more frequently than other
comparable darters. While other darters use their pelvic fins and pectoral fins to
"dart" around the bottoms of streams and rivers, gilt darters swim more often than
they dart.
- Key Behaviors
- natatorial
- motile
Home Range
There is no information available regarding the average home range size of gilt darters.
Communication and Perception
One of the most important perception organs for any fish is their lateral line. It
is a conspicuous line that runs along the middle of their body, from the opercle to
the beginning of their caudal fin. Its functions include water current sensation and
vibration detection. Gilt darters use their eyes, internal ears, and lateral line
to perceive environmental stimuli. There is no other information regarding communication
and perception in this species.
- Communication Channels
- tactile
- Perception Channels
- visual
- tactile
- acoustic
- vibrations
- chemical
Food Habits
Gilt darters are insectivorous, with most prey consisting of aquatic insect larvae.
They locate prey mostly by vision, and feed during the early to middle portion of
the day. From April through August, food tends to be highly abundant but significantly
decreases during September. As a result of the high degree of variability in insect
prey, gilt darters are considered opportunistic feeders and feed mostly when larvae
begin hatching during spring. Primary prey includes
mayflies
,
caddisflies
and other
flies
. They are also known to consume
midges
and
black fly larvae
. One study showed that gilt darters have a preference towards different larvae in
different stages in their life. For example, juveniles feed more on caddisflies in
the first two months of their lives than when they are adults. In addition, young
darters and darters preparing to breed feed more heavily on mayflies than any other
food source.
- Primary Diet
- carnivore
- Animal Foods
- insects
Predation
Little is known about the specific predators of gilt darters; however, the fast water
currents and riffles of rivers and streams make excellent safe zones from predators.
Since darters in general stay at or near the bottom of their habitat, it also keeps
them away from predators that like to hunt for prey near the middle and lower depths
of the water column. Their swimming techniques (e.g., speed and darting) allow them
to outmaneuver a lot of predators as well. Despite this, gilt darters are likely preyed
upon by large piscivorous fish.
Ecosystem Roles
As insectivores, gilt darters may help control insect pest species, and despite a
lack of information on their potential predators, they are likely prey for a number
of different piscivorous fish species as well. Finally, gilt darters play an important
role in mussel reproduction, as they are common hosts for numerous species of mussel
glochidia, including
rabbitsfoot mussels
.
- Ecosystem Impact
- creates habitat
- rabbitsfoot mussel glochidia ( Quadrula cylindrica )
Economic Importance for Humans: Positive
Gilt darters are often used as biological indicators of habitat quality for aquatic
ecosystems.
- Positive Impacts
- research and education
Economic Importance for Humans: Negative
There are no known adverse effects of
Percina evides
on humans.
Conservation Status
Gilt darters are widely distributed throughout the Midwest and northeastern United
States. However, in certain areas throughout their geographic range, they are considered
a species of special concern due to their significant population decline over the
past 50 years. Damming increases siltation rates and turbidity, which buries breeding
grounds. Siltation likely disrupts feeding behavior as well by significantly reducing
water clarity and prey habitat quality. This species has not been evaluated by the
IUCN and has been given no special status by the United States Fish and Wildlife Service.
Other Comments
Prior nomenclature and authority:
Alvordius evides
Jordan and Copeland in Jordan 1877a:44;
Ericosma evides
Jordan 1877b:8-9;
Hadropterus evides
Forbes 1884:65;
Percina evides
Bailey and Gosline 1955:14.
Prior to 1955, gilt darters were referred to in the Minnesota literature as
Hadropterus evides
. The Cannon River specimen referred to by Carlander (1941) and Eddy and Underhill
(1974) is a misidentified
Percina maculata
(Hubbs 1945).
Additional Links
Contributors
Steve Sveine (author), Minnesota State University, Mankato, Robert Sorensen (editor), Minnesota State University, Mankato, John Berini (editor), Animal Diversity Web Staff, Catherine Kent (editor), Special Projects.
- Nearctic
-
living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.
- native range
-
the area in which the animal is naturally found, the region in which it is endemic.
- temperate
-
that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).
- ectothermic
-
animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature
- heterothermic
-
having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.
- bilateral symmetry
-
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
- polyandrous
-
Referring to a mating system in which a female mates with several males during one breeding season (compare polygynous).
- iteroparous
-
offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).
- seasonal breeding
-
breeding is confined to a particular season
- sexual
-
reproduction that includes combining the genetic contribution of two individuals, a male and a female
- fertilization
-
union of egg and spermatozoan
- external fertilization
-
fertilization takes place outside the female's body
- tactile
-
uses touch to communicate
- visual
-
uses sight to communicate
- tactile
-
uses touch to communicate
- acoustic
-
uses sound to communicate
- vibrations
-
movements of a hard surface that are produced by animals as signals to others
- chemical
-
uses smells or other chemicals to communicate
- carnivore
-
an animal that mainly eats meat
- insectivore
-
An animal that eats mainly insects or spiders.
- natatorial
-
specialized for swimming
- motile
-
having the capacity to move from one place to another.
References
Dickson, T. 2008. The Great Minnesota Fish Book . Minneapolis: The University of Minnesota Press.
Eddy, S., T. Surber. 1947. Northern Fishes . Minneapolis: The University of Minnesota Press.
Froese, R. 2010. "FishBase" (On-line). Percina evides. Accessed April 28, 2011 at http://www.fishbase.org/Summary/SpeciesSummary.php?ID=3493&AT=gilt+darter .
Hatch, J. 2004. "Gilt darter" (On-line). Accessed April 28, 2011 at http://hatch.cehd.umn.edu/research/fish/fishes/gilt_darter.html .
Phillips, G., W. Schmid, J. Underhill. 1982. Fishes of the Minnesota region . Minneapolis: The University of Minnesota Press.
Shiels, . 2011. "Pennsylvania Fish and Boat Commission" (On-line). Pennsylvania's Dynamic Darters. Accessed May 01, 2011 at http://www.fish.state.pa.us/education/catalog/darters.html .
2011. "Minnesota Department of Natural Resources" (On-line). Accessed April 28, 2011 at http://www.dnr.state.mn.us/rsg/profile.html?action=elementDetail&selectedElement=AFCQC04090 .
2010. "NatureServe" (On-line). Accessed April 28, 2011 at http://www.natureserve.org/explorer/servlet/NatureServe?searchName=Percina+evides+ .