Influence of water velocity and predation risk on fire salamander (Salamandra infraimmaculata) larval drift among temporary pools in ephemeral streams

2014 ◽  
Vol 33 (3) ◽  
pp. 950-957 ◽  
Author(s):  
Ori Segev ◽  
Leon Blaustein
Keyword(s):  
Predation Risk ◽  
Water Velocity ◽  
Temporary Pools ◽  
Ephemeral Streams ◽  
Larval Drift ◽  
Fire Salamander ◽  
Influence Of Water

Developmental costs of yellow colouration in fire salamanders and experiments to test the efficiency of yellow as a warning colouration

2020 ◽  
Vol 41 (3) ◽  
pp. 373-385 ◽  
Author(s):  
Barbara A. Caspers ◽  
E. Tobias Krause ◽  
Isabelle Hermanski ◽  
Christopher Wiesbrock ◽  
Friedrich-Wilhelm Kastrup ◽  
...  
Keyword(s):  
Predation Risk ◽  
Carabid Beetles ◽  
Colour Pattern ◽  
Natural Habitats ◽  
Yellow Colour ◽  
Risk Of Predation ◽  
Fire Salamander ◽  
Food Conditions ◽  
In Fire ◽  
Salamander Larvae

Abstract Warning colouration reduces predation risk by signalling or mimicking the unpleasantness of prey and therefore increases survival. We tested in two experiments the evolutionary costs and benefits of the yellow colour pattern in fire salamanders (Salamandra salamandra), which display a yellow/black colour pattern usually associated with toxic alkaloids. Our first experiment aimed to test whether the development of colouration is condition dependent and thus related to developmental costs, i.e. influenced by resource availability during the developmental process. Therefore, we reared fire salamander larvae under different nutritional conditions and compared the relative amount of yellow they developed after metamorphosis. Fire salamander larvae reared under limited food conditions had a lower proportion of yellow following metamorphosis than control larvae reared under superior food conditions. In a second experiment we tested whether the proportion of yellow has an impact on the risk of being attacked using artificial models. We tested, in salamander-free and salamander-occupied natural habitats, whether artificial clay models with different proportions of yellow and black receive different attack rates from potential predators (birds, mammals, insects). In clay models the proportion of yellow and the site had a significant effect on predation risk. Models with larger amounts of yellow had fewer bite marks from predators such as carabid beetles and birds, but only in sympatry with salamanders. In conclusion, the early expression of conspicuous colouration seems to be condition dependent and therefore potentially costly. Furthermore, the yellow colouration of fire salamanders act as a signal that potentially reduces their risk of being attacked by predators. Thus, the yellow colouration of fire salamanders seems to represent an adaptive trait that reduces the risk of predation, which can be expressed in higher quantity by individuals of a certain condition.

High nitrification rate with upflow biofiltration

1996 ◽  
Vol 34 (1-2) ◽  
pp. 347-353 ◽  
Author(s):  
J.-G. Peladan ◽  
H. Lemmel ◽  
R. Pujol
Keyword(s):  
Contact Time ◽  
Pilot Scale ◽  
Ammonium Nitrogen ◽  
Water Velocity ◽  
Nitrification Rate ◽  
Air Velocity ◽  
Influence Of Water ◽  
Hydraulic Load ◽  
Series Of Experiments ◽  
Positive Effect

In order to investigate the upper limit of aerated biofilm processes, a series of experiments has been carried out on a pilot scale with a synthetic effluent containing only ammonium nitrogen and inorganic carbon as substrates. The influence of water velocity, air velocity and media height has been studied without the interaction of organic carbon and suspended solids. Under these conditions, the increase of the hydraulic load has a positive effect on the maximum nitrified load, despite the shortening of contact time. The pilot plant was able to nitrify 2.7 kg NH4+-N/m3.d at 14° C with an empty bed hydraulic retention time as short as 6 minutes - under a 30 m3/m2.h hydraulic load. It was also demonstrated that a cubic meter of granular bed presents the same nitrification capacity in a 3 m or in a 4 m media high biofilter, only if placed under the same conditions of air and water velocities. The results confirmed that water velocity significantly improves substrate bulk/biofilm transfer, and demonstrated that neither a contact time - based on the pore volume - as short as 2 minutes nor a media height of 4 m limit the nitrification rate.

Combined filter for ammonia removal – part I: Minimal zeolite contact time and requirements for desorption

1999 ◽  
Vol 39 (8) ◽  
pp. 123-129 ◽  
Author(s):  
G. Dimova ◽  
G. Mihailov ◽  
Tz. Tzankov
Keyword(s):  
Ion Exchange ◽  
Contact Time ◽  
Water Hardness ◽  
Ammonia Concentration ◽  
Water Velocity ◽  
Ammonia Removal ◽  
Design Parameters ◽  
Influence Of Water ◽  
Minimal Contact ◽  
Differential Element

The minimal contact time in removal of ammonia ions by ion-exchange with zeolite, Na-form, is determined using the method of differential element. The relationship between the contact time, the water velocity, the effect of removal and the initial ammonia concentration is investigated. The obtained data serve as a basis for mathematical modeling of the ion exchange kinetics and give valuable information about some design parameters of ion-exchange facilities. Some basic analyses, concerning the desorption of ammonia from zeolite, induced mainly from the cations naturally present in surface waters are made. The influence of water velocity and water hardness on such desorption is investigated. These experimental data and analyses are an essential part of a study, the purpose of which is to investigate the possibilities for ammonia removal and biological regeneration of zeolite in a combined facility, using the processes: ion-exchange, desorption induced by small concentrations of cations and biological nitrification.

Effects of Background Color and Predation Risk on Color Change in Fire Salamander Larvae

2009 ◽  
Vol 55 (4) ◽  
pp. 359-367 ◽  
Author(s):  
Ori Segev
Keyword(s):  
Predation Risk ◽  
Perceived Risk ◽  
Color Change ◽  
White Background ◽  
Color Matching ◽  
Background Color ◽  
Background Matching ◽  
Threat Sensitivity ◽  
Risk Of Predation ◽  
Fire Salamander

The threat-sensitivity hypothesis assumes individuals should demonstrate flexibility in response to perceived predation risk and vary the intensity of anti-predator responses in concert with perceived risk of predation. Substrate color matching is adaptive as it enables organisms to become less conspicuous to both their prey and predators. I hypothesized that newborn fire salamander (Salamandra infraimmaculata) larvae will respond fast through physiological color change to contrasting backgrounds, becoming lighter against a white background and darker against a black background. Additionally, in accordance with the threat-sensitivity hypothesis, I expected a background color x predator interaction—i.e., that predator presence will further enhance the focal larvae color-matching response. To explicitly test these hypotheses I conducted a replicated outdoor mesocosm experiment. I used a two-by-two factorial design: pools of black or white background color crossed with the presence or absence of a larger cannibalistic conspecific. Digital photos of the focal larvae's dorsal view revealed that larval brightness and chroma changed accordingly against the contrasting black and white backgrounds to increase background matching. Although not statistically significant, larvae tended to show a stronger color-change response towards enhanced background matching in the presence of the free predator. Larval survival was strongly reduced in the presence of the larger conspecific, with no apparent effect of background color. This study demonstrates that Salamandra larvae are capable of environmentally induced physiological color change and highlights the need for further investigation into the interplay between threat intensity, mechanisms of risk assessment, and physiological antipredator responses.

Effects of substrate condition on habitat use and survival by white sturgeon (Acipenser transmontanus) larvae and potential implications for recruitment

2011 ◽  
Vol 68 (5) ◽  
pp. 812-822 ◽  
Author(s):  
Steven O. McAdam
Keyword(s):  
Habitat Use ◽  
Water Velocity ◽  
White Sturgeon ◽  
Acipenser Transmontanus ◽  
Spawning Habitat ◽  
Behavioural Responses ◽  
Larval Drift ◽  
Substrate Degradation ◽  
Natural Spawning ◽  
Porous Substrates

To understand links between substrate and recruitment of white sturgeon ( Acipenser transmontanus ), I evaluated the effects of substrate condition on larval drift, hiding, and predation between hatch and 15 days posthatch (dph). Over porous substrates (small gravel = 1.2–1.9 cm; medium gravel = 2.5–5.0 cm; cobble = 10–15 cm), rapid interstitial hiding was observed from 0 to 6 dph at low water velocity (4 cm·s–1), whereas larvae drifted in response to nonporous substrates (sand < 0.2 cm; embedded cobble). Velocities of 20 cm·s–1 led to significantly lower drift only at 1 dph over small gravel. Hiding occurred an average of 2.0–13.3 s after release at 0–6 dph. Predation by sculpins ( Cottus  spp.) on larval sturgeon also decreased significantly in response to porous substrates at 1 dph. The strongest expression of increased hiding and decreased predation when small gravel was available suggests that yolksac larvae prefer small interstitial spaces created by that substrate. Considering behavioural responses in preferred natural spawning habitat suggests yolksac larvae predominantly hide in the vicinity of spawning locations. Identification of strong effects of substrate condition on age-specific drift and survival suggests that substrate degradation may contribute to recruitment limitations for sturgeon.

scholarly journals Influence of Water Temperature on Results of Current Meter Calibration and Measurement

2013 ◽  
Vol 61 (3) ◽  
pp. 208-213 ◽  
Author(s):  
Daniel Mattas ◽  
Libuše Ramešová
Keyword(s):  
Water Temperature ◽  
Rotational Velocity ◽  
Rotational Frequency ◽  
Water Velocity ◽  
Uncertainty Of Measurements ◽  
Influence Of Water ◽  
Type 3 ◽  
Measured Water ◽  
Term Data

Abstract On the basis of the results of calibration of current meters at water of varying temperatures, a hypothesis that water temperature influences measured water velocities was formulated. The analysis of our long-term data showed that the water temperature does have an influence on measured water velocity. This influence can be taken into account for practical purposes as a contribution to the uncertainty of measurements. The influence depends on the type of current meter propeller. This paper presents results obtained for the Ott C-2 current meter with propellers of the types 1, 2, 3, 5 and 6. Our analysis showed that the uncertainty is equal or less than 5% for measurements carried out in water with temperatures above 8°C. The differences between measured water velocities for water temperatures 5°C and 20°C reached maximum 6% (depending on the propeller) in a slowly flowing water (rotational frequency n = 1 s-1). For rotational velocity n ≥ 2 s-1 the differences between velocities measured at water temperatures 5 and 20°C were mostly under 3%. The less influenced propeller is of type 3 for which the uncertainty of measurement does not reach 5% even for water temperature 1°C if the rotational frequency is bigger than 0.7 s-1.

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