Stocked trout do not significantly affect wood frog populations in boreal foothills lakes

2011 ◽  
Vol 68 (10) ◽  
pp. 1790-1801 ◽  
Author(s):  
C.M.M. Schank ◽  
C.A. Paszkowski ◽  
W.M. Tonn ◽  
G.J. Scrimgeour
Keyword(s):  
Trophic Status ◽  
Larval Period ◽  
Wood Frog ◽  
Native Fish ◽  
Negative Consequences ◽  
Lithobates Sylvaticus ◽  
Forage Fishes ◽  
Lake Trophic Status ◽  
Native Populations ◽  
Littoral Habitats

Stocking salmonids into lakes can have negative consequences for some ecosystem components, including amphibians. In the boreal foothills of Alberta, Canada, we compared populations of wood frog ( Lithobates sylvaticus ) at lakes with (n = 5) and without (n = 6) stocked trout over 3 years; all 11 lakes also supported native populations of forage fishes. Abundance and size of adult and young-of-year (YOY) frogs did not differ significantly between stocked and unstocked lakes. We also compared the wood frog population from a twelfth, fishless lake with populations from the 11 fish-bearing lakes (with or without trout); abundance and size of adults and YOY were greater, and YOY emerged earlier in the absence of fish. Based on patterns compiled from a literature review of effects of stocked trout on anuran amphibians, we suggest that characteristics of our study systems, including the presence of native fish, the length of the anuran larval period, lake trophic status, and the existence of complex, littoral habitats, contributed to the lack of major impacts of stocked trout on wood frog populations.

scholarly journals Time-dependent latent inhibition of predator-recognition learning

2019 ◽  
Vol 15 (5) ◽  
pp. 20190183 ◽  
Author(s):  
Adam L. Crane ◽  
Douglas P. Chivers ◽  
Maud C. O. Ferrari
Keyword(s):  
Predation Risk ◽  
Latent Inhibition ◽  
Learning Opportunities ◽  
Predator Recognition ◽  
Wood Frog ◽  
Time Dependent ◽  
Negative Consequences ◽  
Lithobates Sylvaticus ◽  
Frog Tadpoles ◽  
Recognition Learning

To optimally manage an environment with predators, prey must correctly distinguish between cues that are risky and cues that are safe. Even a specific cue that is safe in one area or at a certain time may be dangerous in other situations, and vice versa. Latent inhibition is a cognitive mechanism by which animals fail to learn that a stimulus as risky because they have already learned it as non-threatening via previous encounters with the stimulus in the absence of negative consequences. Here, we demonstrate that latent inhibition of predator-recognition learning in wood frog tadpoles, Lithobates sylvaticus , depends on the timing of their learning opportunities. For 6 days, tadpoles were exposed daily to an initially novel stimulus (salamander odour), either in the morning (11.00–13.00 h) or evening (16.00–18.00 h). The following day, we conditioned tadpoles to recognize the salamander odour as a predator by pairing it with injured tadpole cues, either at the same time as their previous experience or at the opposite time. When tested the following day, latent inhibition occurred under each scenario where the timing of conditioning matched the timing of the pre-exposure. However, tadpoles tested in the morning showed learned fright responses when conditioned in the morning if their pre-exposure had occurred in the evening, whereas individuals tested in the evening showed learned fright responses when conditioned in the evening if their pre-exposure had occurred in the morning. This is the first report of time-dependent latent inhibition of predator-recognition learning, which is likely an important mechanism for correctly managing predation risk and safety.

Littoral zones as sources of biodegradable dissolved organic carbon in lakes

2008 ◽  
Vol 65 (11) ◽  
pp. 2454-2460 ◽  
Author(s):  
E. G. Stets ◽  
J. B. Cotner
Keyword(s):  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Aquatic Macrophytes ◽  
Trophic Status ◽  
Surface Sediments ◽  
Decay Curve ◽  
Lake Area ◽  
Lake Trophic Status ◽  
Littoral Zones ◽  
Biodegradable Dissolved Organic Carbon

A survey of 12 lakes in Minnesota, USA, was conducted to examine the factors controlling variability in biodegradable dissolved organic carbon (BDOC) concentration. The principal question addressed was whether BDOC concentration was more strongly related to lake trophic status or morphometric parameters. BDOC concentration was determined by incubating filtered lake water for a period of 15 months and fitting an exponential decay curve to measured DOC concentrations. BDOC concentrations varied from 73 to 427 µmol C·L–1 and composed 15%–63% of the total DOC pool. There were no significant correlations between BDOC and measures of lake trophic status. Instead, BDOC was most closely associated with the percentage of lake area covered by littoral zone, suggesting a significant source of BDOC from aquatic macrophytes and lake surface sediments.

PCR-DGGE Fingerprinting Analysis of Plankton Communities and Its Relationship to Lake Trophic Status

2009 ◽  
Vol 94 (5) ◽  
pp. 528-541 ◽  
Author(s):  
Li Wu ◽  
Yuhe Yu ◽  
Tanglin Zhang ◽  
Weisong Feng ◽  
Xiang Zhang ◽  
...  
Keyword(s):  
Trophic Status ◽  
Fingerprinting Analysis ◽  
Lake Trophic Status ◽  
Plankton Communities

Influence of prey diet quality on predator-induced traits in wood frog tadpoles (Lithobates sylvaticus)

2021 ◽  
pp. 1-11
Author(s):  
Catherine Chuirazzi ◽  
Melissa Ocampo ◽  
Mizuki K. Takahashi
Keyword(s):  
Predation Risk ◽  
Diet Quality ◽  
Growth And Development ◽  
Chemical Cues ◽  
Wood Frog ◽  
Experimental Conditions ◽  
Lithobates Sylvaticus ◽  
Phenotypic Changes ◽  
Intestinal Length ◽  
Frog Tadpoles

Abstract Diet quality and predation are two critical factors in determining the growth and development of organisms. Various anurans are susceptible to phenotypic changes influenced by these factors. Yet, few studies examined prey diet quality as potential influence over predator-induced traits. Using wood frog tadpoles (Lithobates sylvaticus) as a model species, we investigated the effects of three diet compositions (plant-based, animal-based, omnivorous) crossed with presence or absence of chemical cues from predatory dragonfly larvae (Aeshnidae). After 35 days, we recorded 11 morphological measurements, Gosner stage, and intestinal length of tadpoles to assess phenotypic changes under the six different experimental conditions. Our results showed the additive effects of both diet quality and predator chemical cue without detection of interactions between the two. Tadpoles receiving the omnivorous diet grew and developed faster with wider denticle rows than those receiving the plant or animal diets. The growth and development of tadpoles receiving only the animal diet were significantly hindered. These results emphasize the importance of diet quality in the growth and development of larval wood frogs. Chemical cues from predators significantly reduced tadpole body size but, in contrast to previous findings, did not affect tail size. Our experimental procedure of providing water containing predator and injured conspecific chemical cues on a weekly basis likely provided relatively weak predation risk perceived by tadpoles compared to previous studies using caged predators. The predator environment in our experiment, however, represents one ecologically relevant scenario in which predation risk is not urgent.

Phytoplankton communities in the crater lakes of western Uganda, and their indicator species in relation to lake trophic status

2019 ◽  
Vol 107 ◽  
pp. 105563 ◽  
Author(s):  
Angela Nankabirwa ◽  
Wannes De Crop ◽  
Thijs Van der Meeren ◽  
Christine Cocquyt ◽  
Pierre-Denis Plisnier ◽  
...  
Keyword(s):  
Indicator Species ◽  
Trophic Status ◽  
Crater Lakes ◽  
Lake Trophic Status ◽  
Phytoplankton Communities ◽  
Western Uganda

Postglacial shifts in lake trophic status based on a multiproxy study of a humic lake

The Holocene ◽  
2014 ◽  
Vol 25 (3) ◽  
pp. 495-507 ◽  
Author(s):  
Danuta Drzymulska ◽  
Magdalena Fiłoc ◽  
Mirosława Kupryjanowicz ◽  
Krystyna Szeroczyńska ◽  
Piotr Zieliński
Keyword(s):  
Trophic Status ◽  
Humic Lake ◽  
Lake Trophic Status

Profundal Sediment Organic Content and Physical Character Do Not Reflect Lake Trophic Status, but Rather Reflect Inorganic Sedimentation and Exposure

1992 ◽  
Vol 49 (7) ◽  
pp. 1431-1438 ◽  
Author(s):  
D. J. Rowan ◽  
J. Kalff ◽  
J. B. Rasmussen
Keyword(s):  
Organic Matter ◽  
Water Content ◽  
Bulk Density ◽  
Trophic Status ◽  
Organic Content ◽  
Sedimentation Rates ◽  
Lake Surface ◽  
Lake Trophic Status ◽  
Sediment Organic Content ◽  
Lake Surface Area

An analysis of profundal sediment data from 83 north-temperate lakes shows that increasing inorganic sedimentation and exposure (or lake surface area) results in lower organic content and water content, and greater bulk density. Because sedimentation rates are unavailable for most lakes, we estimate sedimentation rates from readily available catchment sediment loads using a mass-balance model. The mass-balance estimate of sediment retention (per square metre of depositional zone) is an excellent predictor of measured inorganic sedimentation rates for a data set covering 19 lakes (R2 = 0.92). Multiple regressions are used to predict organic content, water content, and bulk density of profundal sediment from inorganic sedimentation rates and either exposure or lake surface area, which are surrogates for the energy of the depositional environment. These analyses explain 76, 74, and 66% of the between-lake variation in the three sediment parameters, respectively. Sediment organic content is not related to lake trophic status (chlorophyll a) and is negatively correlated with net organic matter sedimentation rates. The common occurrence of organic-rich sediments in oligotrophic shield lakes is, therefore, not a reflection of high organic matter inputs, but rather the extremely low inputs of mineral sediments to these lakes.

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