The age and growth of male and female Pterygoplichthys

disjunctivus in Volusia Blue Spring, Florida

Jennifer GoochMentor: Dr. Gibbs

IntroductionVermiculated Sailfin Catfish(Pterygoplichthys disjunctivus)

Loricariidae family Native to the Madeira River drainage of Brazil and BoliviaInvasive to some tropical & subtropical regions.

Credit: Dr. Gibbs

Characteristics of Invasive SpeciesThis catfish demonstrates common

invasive species characteristics such as:

Lack of sufficient predators in invaded areas

High fecundityAdaptabilityThey can change ecosystem dynamics

Introduction: ImpactsDisrupts aquatic food chainsCauses changes in aquatic plant

communitiesErodes banks in the waterImpacts native species

http://nas.er.usgs.gov/XIMAGESERVERX/2007/20071026161928.JPG

http://4.bp.blogspot.com/_SnbFzIYLZR8/SwQtB6jOoWI/AAAAAAAAA90/vkcGT1Y6M7I/s400/ManateeCoveredinCatfish.jpg

Introduction: Previous StudiesGibbs et al. (2008 & 2013)

Looked at the age, growth, and reproductive patterns of P. disjunctivus in Volusia Blue Spring.Speared the catfishSacrificed them (MS222)Measured their length, mass, thicknessExtracted catfish lapillal otolithsRead otolith rings under a compound

microscope to estimate age

Intoduction: Previous StudiesLapilla Asteriscu

sSagitta

Credit: Dr. Gibbs

Introduction: Previous Studies• Otoliths: CaCO3 ear

stones found in the semicircular canals of bony fish.

• Help with orientation, balance, and sound detection.

Otolith

Otolith in semicircular canal

Credit: Dr. Gibbs

http://www.nmfs.noaa.gov/gallery/images/images/photos/20110404_5589334674.jpg

Introduction: Previous Studies

Age determined by

counting otolith band pairs

Gibbs et al. (2013): seasonal changes seen in otoliths

Fast growthSlow growth

Credit: Dr. Gibbs

Introduction: Previous StudiesGibbs et al. (2013) concluded:

P. disjunctivus thrives in Volusia Blue Spring due to warmer year-round temperatures compared to its native habitat, year-round food availability, and lack of predators

Catfish mature at 2 yearsLive up to 5 yearsReach up to 52cm in length

Introduction- Our studyOur study was a

continuation of Gibbs et al. (2013).

Observations suggested that mature males are longer & leaner than females…but is there a difference in growth rates?

Hypothesis: Male and female P. disjunctivus in Volusia Blue Spring will grow at different rates throughout their lives.

♀

♂Credit: Dr. Gibbs

Credit: Dr. Gibbs

Methods185 otoliths from 2008-2011169 otoliths from 2012-2014354 total (M: 178 F: 163)Otoliths mounted on glass slides

with superglue, each was given a number

Made sagittal sections by grinding the otoliths with fine grit sand and polishing paper on a modified turntable

Viewed otoliths on a Zeiss Axiostar Plus compound microscope.

Counted otolith growth band pairs to estimate age

Credit: Devin Burris

Credit: Devin Burris

MethodsTwo individuals read each otolith 3 times to validate

age estimatesPrecision of measurements (consistency among &

between readers) was established with:Coefficient of Variation (CV) calculated for each fish

Eliminated any fish with highly variable results Average CV calculated for all fish combined

Index of Precision (D = CV/number of otolith readings3)Graphed estimated age vs. SL for all mature fish and

for mature males vs. femalesAnalysis of covariance (ANCOVA) was used to compare

male and female growth rates

Age estimates from both readers were pooledCV was calculated for each fish, and highly

variable fish (CV >20) were eliminated as unreliable (n=10)

Average CV was calculated for the remaining fish and found to be 8.39 (acceptable CV is <10)

D was found to be 3.54 (acceptable D is <5)

Results

Results

1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 60

10

20

30

40

50

60

f(x) = 7.21543095051907 x + 15.061347191796R² = 0.461774680898884

Age (years)

Stan

dard

Len

gth

(cm

)

Males (n=172)

Results

1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 60

10

20

30

40

50

60

f(x) = 7.21487597452339 x + 13.2721923494749R² = 0.419679135402064

Age (years)

Stan

dard

Len

gth

(cm

)

Females (n= 139)

ResultsANCOVA-no difference in male/female growth rates (p=0.70)-males are significantly larger than females (p=0.002)

1 1.5 2 2.5 3 3.5 4 4.5 5 5.50

10

20

30

40

50

60

f(x) = 7.21487597452339 x + 13.2721923494749R² = 0.419679135402064

f(x) = 7.21543095051907 x + 15.061347191796R² = 0.461774680898884

Male Age (years)

Stan

dard

Len

gth

(cm

)

Male & Females (n= 311)

ConclusionOur hypothesis that male and female P.

disjunctivus in Volusia Blue Spring will grow at different rates throughout their lives was not supported (P = 0.70).

However, males were significantly larger than females (P= 0.002). Males and females do not have different

growth rates, but they seem to grow in different dimensions.

ConclusionBy understanding their growth rates,

we are able to contribute to the knowledge of Pterygoplichthys disjunctivus’s basic biology.

Our study can help managers find ways to control P. disjunctivus populations in Volusia Blue Spring & in other areas where this invasive species thrives.

Future StudiesMore otolith reads for more

accurate dataHow is P. disjunctivus getting

bigger?Growing mostly during the first two years?

Differential growth?

AcknowledgementsDr. GibbsDevin BurrisDr. BenningtonDr. FarrellDr. LindBlue Spring State ParkStetson Biology DepartmentFriends & family

Questions?

References Cited Gibbs, M., Shields, J., Lock, D., Talmadge, K., Farrell, T. 2008. Reproduction

in an invasive exotic catfish Pterygoplichthys disjunctivus in Volusia Blue Spring, Florida, U.S.A. Journal Of Fish Biology, 73(7): 1562-1572.

Gibbs, M., Kurth, B., & Bridges, C. 2013. Age and growth of the loricariid catfish Pterygoplichthys disjunctivus in Volusia Blue Spring, Florida. Aquatic Invasions, 8(2): 207-218.

Hoover, J. J., Killgore, K. J., Cofrancesco, A. F. 2004. Suckermouth catfishes: threats to aquatic ecosystems of the United States? Aquatic Nuisance Species, 4: 1-13.

Rueda-Jasso, R.A., Campos-Mendoza, A., Arreguin-Sanchez, F., Diaz-Prado, E., Martinez-Palacio, C.A. 2013. The biological and reproductive parameters of the invasive armored catfish Pterygoplichthys disjunctivus from Adolfo López Mateos El Infiernillo Reservoir, Michoacán-Guerrero, Mexico. Revista Mexicana De Biodiversidad, 84: 318-326.