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Abstract

Declines of amphibians have been attributed to many factors including habitat degradation. The introduction of grass carp (Ctenopharyngodon idella) as a biological agent for aquatic plant control in ponds and lakes managed narrowly for human recreation has likely contributed to amphibian declines through massive plant removal and associated habitat simplification and thus degradation. This research examined the interactions among grass carp and three Midwestern aquatic plants (Jussiaea repens, Ranunculus longirostris, and R. flabellaris) that may be of value in rehabilitation of habitats needed by amphibians. The feeding preference study found that C. idella avoided eating both J. repens and R. longirostris. Ranunculus species studied to date contain a vesicant toxin called ranunculin that is released upon mastication. The study that compared the effects of R. flabellaris, J. repens and a control food administered by tube feeding to C. idella found significant lesions only in the mucosal epithelium of the individuals exposed to R.flabellaris. The avoidance by C. idella of J. repens and R. longirostris in the feeding preference study, and the significant toxicity of R. flabellaris demonstrated by the dosing study, indicate these plants warrant further examination as to their potential effectiveness in aquatic amphibian habitat rehabilitation.

A Review of Grass Carp and Related Species Literature on Diet, Behavior, Toxicology, and Physiology Focused on Informing Development of Controls for Invasive Grass Carp Populations in North America

“…) [1] Potamogeton amplifolius [17] citing [191]; (b) [175] Potamogeton crispus [158]; (b) [159]; (c) [183]; (d) [216]; (e) [20]#; (f) [165]; (g) [144]; (h) [159]; (i) [188]; (j) [72] Potamogeton foliosus (a) [183]; (b) [20]#; (c) [192] citing [193], [194], and V. Krupauer, 1967; (d) [195]; (e) [209] Table 5. Cont.…”

“…Grass carp orally dosed with a water extract of water buttercup (Ranunculus aquatilis var. diffusus) develop intestinal lesions; the toxin believed to cause these effects is ranunculin [216]. Research of detoxification of Jatropha curcas kernel meal as a food source for common carp production, [716], referring to [717,718], describes the high level of antinutrients such as trypsin inhibitor, lectin, phytate, and the presence of toxic phorbol esters, which make this food source toxic to carp.…”

The feeding ecology of grass carp: A review

“…As a long‐lived herbivore, normal diploid grass carp have a life span of typically 12–15 years and the record shows its maximum lifetime in the wild for 21 years 20,21 . Triploid grass carp were reported to possess a mean lifespan of about 11 years 22 through its life span may be longer at the condition of higher latitudes with shorter growing seasons and lower water temperatures 23 .…”

“…As a long-lived herbivore, normal diploid grass carp have a life span of typically 12-15 years and the record shows its maximum lifetime in the wild for 21 years. 20,21 Triploid grass carp were reported to possess a mean lifespan of about 11 years 22 through its life span may be longer at the condition of higher latitudes with shorter growing seasons and lower water temperatures. 23 The addition of exogenous chemicals in the water such as the application of herbicides to restrict the aquatic plant blooms in ecosystems, has the potential to reduce the growth and lifespan of grass carp.…”