Modelling mercury concentrations in prey fish: Derivation of a national-scale common indicator of dietary mercury exposure for piscivorous fish and wildlife

2013 ◽  
Vol 176 ◽  
pp. 234-243 ◽  
Author(s):  
David C. Depew ◽  
Neil M. Burgess ◽  
Linda M. Campbell
Keyword(s):  
Mercury Exposure ◽  
Prey Fish ◽  
National Scale ◽  
Piscivorous Fish

Feeding selectivity of a guild of piscivorous fish in mangrove areas of north-west Australia

1986 ◽  
Vol 37 (3) ◽  
pp. 329 ◽  
Author(s):  
SJM Blaber
Keyword(s):  
Prey Species ◽  
Rank Order ◽  
Feeding Selectivity ◽  
Resident Species ◽  
Prey Fish ◽  
North West ◽  
Carcharhinus Limbatus ◽  
Piscivorous Fish ◽  
Linear Index

Piscivorous fish are unusually abundant in mangrove creeks in the Dampier region of north-west Australia (20°40′S.,1 16°40′E.). Penetration of mangroves by predators is relevant to the role of such waters as nursery grounds. Caranx ignobilis, Carcharhinus limbatus, Scomberoides commersonianus and Scornberomorus semifasciatus were the most numerous predators. More than 50% of suitably sized potential prey fish species were consumed; the most common prey were Atherinidae, Gobiidae, Ambassis sp. and Sillago spp. Small (1-9 cm), permanently resident species constituted 60% of prey, and juveniles of larger species made up the balance. Feeding selectivity was assessed on three electivity indices and caution in their use is emphasised. Although the results conflicted, only the linear index could be statistically tested and two interesting points emerged. Firstly, of the three most common prey species, two were positively selected and one negatively selected, and the remainder were consumed in approximate proportion to their abundances. Secondly, the indices gave similar rank order preferences, with Atherinidae, Sillago spp. and Harengula sp. the most preferred and Ambassis sp. the least preferred.

scholarly journals Physiological responses of anti-predation in prey fish to the threat of piscivorous fish in different underwater visibility conditions

2018 ◽  
Vol 108 (0) ◽  
Author(s):  
Leandro Fabrício Fiori ◽  
Bruno R. S. Figueiredo ◽  
Audrei Pavanello ◽  
Vander Silva Alves ◽  
Paulo Cezar de Freitas Mathias ◽  
...  
Keyword(s):  
Plasma Glucose ◽  
Plasma Cortisol ◽  
Physiological Responses ◽  
Visual Signals ◽  
Prey Fish ◽  
Piscivorous Fish ◽  
Glucose Levels ◽  
Significant Difference ◽  
Cortisol Levels ◽  
Hunting Strategy

ABSTRACT Considering that the anti-predation behaviour of prey fishes may vary with predator hunting strategy, we experimentally investigated the physiological responses of Astyanax bimaculatus (Linnaeus, 1758) shoals to the presence of two piscivorous fish species with different hunting modes: sit-and-wait and active pursuit. In addition, we evaluated the influence of underwater visibility conditions on the interaction between predator and prey. We tested the hypotheses that: (i) prey plasma cortisol and glucose levels vary according to piscivore hunting strategy, and (ii) no reduction in plasma glucose and cortisol levels takes place in turbid environments due to the inability of prey to accurately recognise predators by non-visual signals. The results revealed that the presence of piscivorous fish increased plasma cortisol levels in prey, with no significant difference recorded between the two hunting strategy treatments. We also observed no significant change in plasma glucose levels in different water transparency conditions. Thus, we conclude that physiological changes in the selected prey fish do not vary with predator hunting mode, and it is therefore necessary to consider the ability of the prey to recognise and evaluate danger, regardless of piscivore hunting strategy.

Estimating Mercury Exposure of Piscivorous Birds and Sport Fish Using Prey Fish Monitoring

2015 ◽  
Vol 49 (22) ◽  
pp. 13596-13604 ◽  
Author(s):  
Joshua T. Ackerman ◽  
C. Alex Hartman ◽  
Collin A. Eagles-Smith ◽  
Mark P. Herzog ◽  
Jay Davis ◽  
...  
Keyword(s):  
Mercury Exposure ◽  
Prey Fish ◽  
Piscivorous Birds ◽  
Sport Fish ◽  
Fish Monitoring

scholarly journals Effects of fish predation on density and size spectra of prey fish communities in lakes

2016 ◽  
Vol 73 (4) ◽  
pp. 506-518 ◽  
Author(s):  
Thomas Mehner ◽  
Caroline Keeling ◽  
Matthias Emmrich ◽  
Kerstin Holmgren ◽  
Christine Argillier ◽  
...  
Keyword(s):  
Size Structure ◽  
Prey Size ◽  
Fish Communities ◽  
Fish Predation ◽  
Prey Fish ◽  
Benthivorous Fish ◽  
Size Spectra ◽  
Predator Prey ◽  
Piscivorous Fish ◽  
Predation Effects

Planktivorous and benthivorous fish have been documented to influence the density and size structure of their prey communities in lakes. We hypothesized that piscivorous fish modify their prey fish communities in the same way and sought to find evidence for such predation effects from a comparison across 356 lakes located in nine European ecoregions. We categorized individual fish as being piscivore, nonpiscivore, or prey of piscivores, depending on species and individual size. We calculated piscivore, nonpiscivore, and piscivore prey densities, respectively, and fit linear abundance size spectra (SS) on lake-specific piscivore, nonpiscivore, and piscivore-prey size distributions. Multiple linear regressions were calculated to quantify the effect of piscivore density and SS slopes on nonpiscivore and piscivore-prey densities and SS slopes by accounting for potentially confounding factors arising from lake morphometry, productivity, and local air temperature. Piscivore density correlated positively with piscivore-prey density but was uncorrelated with density of nonpiscivores. Across a subset of 76 lakes for which SS slopes of piscivores were statistically significant, SS slopes of piscivores were uncorrelated with SS slopes of either nonpiscivores or piscivore prey. However, densities of piscivores, nonpiscivores, or piscivore prey were a significant negative predictor of SS slopes of the respective groups. Our analyses suggest that direct predation effects by piscivorous fish on density and size structure of prey fish communities are weak in European lakes, likely caused by low predator–prey size ratios and the resulting size refuges for prey fish. In contrast, competition may substantially contribute to between-lake variability in fish density and size.

Spatial regularities between non-immigrant and immigrant numbers in Canada

2014 ◽  
Vol 11 (1) ◽  
pp. 90-100
Author(s):  
Yigit Aydede
Keyword(s):  
Fixed Effects ◽  
Spatial Scales ◽  
National Scale ◽  
Pooled Data

The present study intends to reveal spatial regularities between non-immigrant and immigrant numbers in two different ways. First, it questions the existence of those regularities when spatial scales get finer. Second, it uses pooled data over four population censuses covering the period from 1991 to 2006, which enabled us to apply appropriate techniques to remove those unobserved fixed effects so that the estimations would accurately identify the linkage between local immigrant and non-immigrant numbers. The results provide evidence about the existence of negative spatial regularities between non-immigrant and immigrant numbers in Canada at national scale.

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