The effects of salinity, temperature, and Pomacea maculata

The effects of salinity, temperature, and Pomacea maculata

The effects of salinity, temperature, and
Pomacea maculata herbivory on
Southwest Florida aquatic vegetation
by: Shannan Mcaskill and Alexandra Rodriguez
The Island Apple Snail
● Scientific Name: Pomacea maculata
● Native to South America 1
● Negative ecosystem impacts 3,4:
○ Competitive exclusion of native snail
○ Parasites
○ Inhibit wetland restoration
○ Agricultural pest
○ Alters macrophyte community
structure
○ High consumption/growth rate
Tape Grass: What is it and Why is it
Important?
● Scientific name: Vallisneria americana
● Deep-rooted, freshwater macrophyte 5
○ Tolerates about 10 psu salinity
● Ecological importance 2,5:
○ food (manatees)
○ shelter (nursery)
○ water clarity
○ reduces erosion
Tape Grass in the Caloosahatchee
(Doering et al., 1999)
Feeding Trials
One-way ANOVA
● Temperature increased grazing rate (P-value: 0.0049).
One-way ANOVA (log10 transform)
● Salinity has a significant effect on grazing rate (P: <0.0001)
Feeding Choice
Monoculture
Polyculture
Both
CONTROL
FREE CHOICE
Two-way ANOVA
Two-way ANOVA
● Conclusive preference for V. americana when
presented with free choice (P-value: 0.0185)
●
●
Affinity for H. verticillata in monoculture, V.
americana in polyculture
Compensatory feeding - may have eaten more
Hydrilla because it is a poorer food choice
Two-way ANOVA (square root transform)
● Conclusive preference for V. americana in monoculture and polyculture (Pvalue: <0.0001)
● More evidence that Pomacea maculata is not an effective way to manage
invasive aquatic vegetation.
Mesocosm
Experiment
Week 4
0 psu with snails
0 psu without snails
5 psu with snails
5 psu without snails
10 psu with snails
10 psu without snails
15 psu with snails
15 psu without snails
Two-way ANOVA (square root transform)
● Significant difference between tanks containing snails and tanks with no snails (P-value: 0.0087)
Nominal Logistic- time (weeks) vs. treatment (salinity) on percent snail mortality
● No significant interactive effect between time and treatment.
● Statistically significant difference between treatment (P-value: <0.0001).
Questions?
References
•1Burlakova, L.E., Padilla, D.K., Karatayev, A.Y., Hollas, D.N., Cartwright, L.D., and Nichol, K.D., 2010, Differences in population dynamics and potential
impacts of a freshwater invader driven by temporal habitat stability, Biological Invasions, Vol. 12 (4), pp.927-941
•2Doering, P. H., Chamberlain, R. H., Donohue, K. M., and Steinman, A. D., 1999, Effect of salinity on the growth of Vallisneria americana from the
Caloosahatchee Estuary (South Florida), Florida Scientist, Vol.62(2), pp.89-105
•3Horgan, F.G., Stuart, A.M., and Kudavidanage, E.P., 2014, Impact of invasive apple snails on the functioning and services of natural and managed
wetlands, Acta Oecologica, Vol.54, p.90-100
•4Karatayev, A. Y., Burlakova, L. E., Karatayev, V. A., and Padilla, D. K., 2009, Introduction, distribution, spread, and impacts of exotic freshwater
gastropods in Texas, Hydrobiologia, 619(1), pp.181-194
•5Wigand, C., Wehr, J., Limburg, K., Gorham, B., Longergan, S., and Findlay, S., 2000, Effect of Vallisneria americana (L.) on community structure and
ecosystem function in lake mesocosms, Hydrobiologia, Vol.418(1), pp.137-146