Bluegill Sunfish (Lepomis macrochirus), Pumpkinseed Sunfish (Lepomis
gibbosus), and Green Sunfish (Lepomis cyanellus) are all common freshwater
Sunfishes in North America of the family Centrarchidae. All of the young
cohabit the shallow littoral zones of lakes or ponds. As adults, they begin to
dominate different sections of the water. Pumpkinseed and Green Sunfish
dominate the shallow portion of the littoral zone which pushes Bluegill Sunfish
to deeper water through competition (Werner and Hall, 1977). Pumpkinseed
Sunfish have special jaw apparatus that allows them to crush and consume snails
more effectively than the other two fish (Keast, 1978). Trematodes, or parasitic
flatworms, commonly infect fish and have been known to be in all 3 fishes. A
key stage in parasitic flatworms includes snails, who are intermediate hosts
responsible for infecting fish. Snails are primarily found in the shallow littoral
zone.
Bluegill
14%
4%
Pumpkinseed
P.minimum
centrarchi
86%
96%


N=26
The most common parasite in
Bluegills was the larval
trematode (metacercarie) of
P. minimum centrarchi.
Shannon Diversity Index (EH = 0.59)
calculations show that Bluegills had medium
community evenness compared to the other
2 fishes
15%
P.minimum
centrarchi
Other
EH = 0.59
Green Sunfish

85%
Other
N=28
EH = 0.23



Shannon Diversity Index (EH = 0.23)
calculations show that Pumpkinseeds had
the lowest community evenness

Other
N=25
EH = 0.66
The most common parasite
in Pumpkinseeds was the
larval trematode (metacercarie) of P. minimum
centrarchi.
I hypothesize there will be a significant difference in trematode prevalence and
mean intensity between fishes, with the highest prevalence and intensity being
in Pumpkinseed fishes, due to their feeding behavior and close proximity to
snails.
Posthodiplostomum spp.
The most common parasite in
Green Sunfish was the larval
trematode (metacercarie) of
Posthodiplostomum spp.
Shannon Diversity Index (EH = 0.66)
calculations show that Green Sunfsih had
the highest community evenness
There is no significant difference in larval trematode
intensities of P.minimum centrarchi between
Pumpkinseed and Bluegill Sunfish in all organs.
There is a significant difference in larval trematode
intensities of Posthodiplostomum spp. in Green
Sunfish and larval trematode P.minimum centrarchi
in both Bluegill and Pumpkinseed Sunfish, with
lower intensities in all organs except the Gonads,
where the intensity of Posthodiplostomum spp is
higher than that of P.minimum centrarchi.
L.Trematode Intensity vs. Fish Length
500
Fish Sampling
Fish were sampled twice a month for the summer, spring, and fall seasons at
Weston Mills Pond, New Jersey.
Small fish were caught using a seining net; Larger fish using a fishing reel. Fish
were transported in 2 five gallon buckets with oxygen, and stored live for no
longer than 5 days in 2 fifty gallon tanks with oxygen and filters.
Fish Identification:
Fish were indentified using Minnesota’s
Department of Natural Resource’s guide on
Sunfish Biology and Identification.
Fish Dissection
Fish were euthanized via pithing, using a
thin scalpel inserted into the brain.
Fish were then placed on a dissecting tray
for dissection.
Fish species, weight, and standard length
were measured. Parasites from each organ
were counted.
Parasite Identification:
Identification was done using the text, “Parasites of North American
Freshwater Fishes” by Glenn L.Hoffman . More specific identification used
dichotomous keys from this text.
# Larval Trematode
R² = 0.807
400
R² = 0.6836
300
200
R² = 0.2436
100
0
3
4
5
6
7
8
9
10
Fish Length (cm)

Larval Trematode ( or Metacercarie) intensity is
correlated with host size for Bluegills and
Pumpkinseeds but not Greensunfish.
I reject the hypothesis that Pumpkinseed Sunfish have higher intensities and
prevalence of larval trematodes, as larval trematode prevalence in all 3 fish are
similar and there is no significant difference in total larval trematode levels
between Pumpkinseed and Bluegill sunfish.
 There is however, a significant difference in total larval trematode levels between Green and Pumpkinseed Sunfish, and
Green and Bluegill Sunfish. This may be due to small size of Green Sunfish captured.
1.
Hoffman, Glenn L. Parasites of North American Freshwater Fishes. Berkeley: Univ. of California, 1967.
2.
Keast, Allen. "Feeding Interrelations between Age-groups of Pumpkinseed (Lepomis Gibbosus) and Comparisons with Bluegill (Lepomis Macrochirus)." Journal of the Fisheries Research Board of Canada 35.1 (1978): 12-27.
3.
Mittelbach, Gary G. "Predation and Resource Partitioning in Two Sunfishes (Centrarchidae)." Ecology 65.2 (1984): 449-513.
4.
Osenberg, Craig W., and Gary G. Mittlebach. "Effects of Body Size on the Predator-Prey Interaction Between Pumpkinseed Sunfish and Gastropods." Ecological Monographs 59.4 (1989): 405-32
5.
"Sunfish Biology and Identification." Minnesota DNR. N.p., n.d.
6.
Werner, Earl E., Dennis R. Laughlin, Donald J. Wagner, Leni A. Wilsmann, and Frederick C. Funk. "Habitat Partitioning in a Freshwater Fish Community Habitat Partitioning in a Freshwater Fish Community." Journal of the Fisheries Research Board of
Canada 34.3 (1977): 360-70.