scholarly journals Predation of two common native frog species (Litoria ewingi and Crinia signifera) by freshwater invertebrates

2014 ◽  
Vol 62 (6) ◽  
pp. 483 ◽  
Author(s):  
Natasha J. Wilson ◽  
Jamie E. Seymour ◽  
Craig R. Williams
Keyword(s):  
Aquatic Invertebrates ◽  
South Australia ◽  
Aquatic Invertebrate ◽  
Freshwater Crayfish ◽  
Life Stages ◽  
Freshwater Invertebrates ◽  
Invertebrate Predator ◽  
Cherax Destructor ◽  
Invertebrate Predators ◽  
Frog Species

The primary aim of this study was to identify aquatic invertebrate predators of amphibian eggs and tadpoles in an area of South Australia. The presence and abundance of aquatic invertebrates was monitored at four field sites for a period of 5–6 months; this revealed notonectids, freshwater crayfish and odonates to be amongst the most common invertebrate predator types. The ability of these predators to consume eggs and tadpoles of the native Australian frogs Litoria ewingi and Crinia signifera was then investigated. Freshwater crayfish (Cherax destructor) were the most prolific consumers of frog eggs and tadpoles. The notonectid Enithares woodwardi significantly impacted tadpole survivorship for both species while Anisops sp. was less successful at capturing and consuming these tadpoles. Caddisfly nymphs (Lectrides varians and Leptorussa darlingtoni) reduced egg survivorship but not to the same extent as C. destructor. Unlike some predators, which prey upon particular life stages, freshwater crayfish are large, polytrophic omnivores that can act as important predators of both anuran eggs and tadpoles. Given that predation is a key source of mortality in juveniles, identification of likely common predators is useful for understanding the regulation of amphibian populations.

Genetic-Variation in Yabbies, Cherax-Destructor and C-Albidus (Crustacea, Decapoda, Parastacidae), Indicates the Presence of a Single, Highly Sub-Structured Species

1994 ◽  
Vol 42 (6) ◽  
pp. 745 ◽  
Author(s):  
NJH Campbell ◽  
MC Geddes ◽  
M Adams
Keyword(s):  
Population Structure ◽  
Genetic Variation ◽  
Morphological Variability ◽  
South Australia ◽  
Significant Heterogeneity ◽  
Freshwater Crayfish ◽  
Drainage Basins ◽  
Cherax Destructor ◽  
Variable Morphology ◽  
High Degree

The high degree of morphological variability exhibited by yabbies (Cherax destructor Clark and C. albidus Clark) prompted this investigation of genetic variation, specifically addressing the taxonomy and population structure of these freshwater crayfish. Yabbies from 14 localities in South Australia and Victoria were classified morphologically and examined electrophoretically at 35 gene loci. Morphometric analysis confirmed the existence of two morphotypes with allopatric distributions. Genetic divergence between morphotypes was relatively low (average fixed differences = 4.72%, average Nei D = 0.085) compared with known interspecific levels-both generally and within the genus Cherax-and levels of divergence between populations within the morphotypes. Subspecific status for albidus is consequently advocated. This species shows evidence of a high degree of genetic fragmentation, with significant heterogeneity occurring at two or more loci between even the closest localities. Gene flow appears to be severely restricted even within drainage basins and a 'stepping-stone' model of population structure may be appropriate. This high degree of genetic fragmentation may explain the variable morphology of this species although phenotypic plasticity could also play a role. Genetic variation was chaotically distributed (the only consistent geographic pattern of divergence corresponding to the albidus morphotype), probably reflecting numerous translocations of this species. The results highlight the need for taxonomy and management to be based on genetic as well as morphological subdivisions.

Phylogeny of the Australian freshwater crayfish Cherax destructor-complex (Decapoda : Parastacidae) inferred from four mitochondrial gene regions

2005 ◽  
Vol 19 (3) ◽  
pp. 209 ◽  
Author(s):  
Thuy T. T. Nguyen ◽  
Christopher M. Austin
Keyword(s):  
16S Rrna ◽  
Cytochrome Oxidase ◽  
Mitochondrial Gene ◽  
Large Subunit ◽  
Strong Support ◽  
Interspecific Variation ◽  
Rrna Gene ◽  
Freshwater Crayfish ◽  
Cherax Destructor ◽  
Australian Freshwater

The phylogenetic relationships among 32 individuals of Australian freshwater crayfish belonging to the Cherax destructor-complex were investigated using a dataset comprising sequences from four mitochondrial gene regions: the large subunit rRNA (16S rRNA), cytochrome oxidase I (COI), adenosine triphosphatase 6 (ATPase 6), and cytochrome oxidase III (COIII). A total of 1602 bp was obtained, and a combined analysis of the data produced a tree with strong support (bootstrap values 94–100%) for three divergent lineages, verifying the phylogenetic hypotheses of relationships within the C. destructor species-complex suggested in previous studies. Overall, sequences from the 16S rRNA gene showed the least variation compared to those generated from protein coding genes, which presented considerably greater levels of divergence. The level of divergence within C. destructor was found to be greater than that observed in other species of freshwater crayfish, but interspecific variation among species examined in the present study was similar to that reported previously.

scholarly journals Freshwater aquatic invertebrates on the Isle of May, Scotland

2021 ◽  
Vol 27 (3) ◽  
pp. 42-47
Author(s):  
C.R. Macadam
Keyword(s):  
Climate Warming ◽  
Aquatic Invertebrates ◽  
Invertebrate Fauna ◽  
Freshwater Invertebrates ◽  
Freshwater Invertebrate ◽  
Freshwater Habitats

The invertebrate fauna of freshwater habitats on the Isle of May, Scotland was investigated and compared with the results from surveys undertaken in 1958. Overall, the freshwater invertebrate fauna appears to be diminished. However, several species were recorded as new to the Isle of May. Although the reasons for the apparent decline in freshwater invertebrates on the island are unclear, an increase in the temporary nature of the habitats due to climate warming may be a contributing factor.

scholarly journals Testing the effectiveness of pyrazine defences against spiders

Chemoecology ◽  
2020 ◽  
Vol 30 (4) ◽  
pp. 139-146
Author(s):  
Emily R. Burdfield-Steel ◽  
Jutta M. Schneider ◽  
Johanna Mappes ◽  
Susanne Dobler
Keyword(s):  
Single Species ◽  
Predator Species ◽  
Chemical Defences ◽  
Invertebrate Predator ◽  
Invertebrate Predators ◽  
Tiger Moth ◽  
Vast Variation ◽  
Web Building ◽  
Hunting Tactics

Abstract Insects live in a dangerous world and may fall prey to a wide variety of predators, encompassing multiple taxa. As a result, selection may favour defences that are effective against multiple predator types, or target-specific defences that can reduce predation risk from particular groups of predators. Given the variation in sensory systems and hunting tactics, in particular between vertebrate and invertebrate predators, it is not always clear whether defences, such as chemical defences, that are effective against one group will be so against another. Despite this, the majority of research to date has focused on the role of a single predator species when considering the evolution of defended prey. Here we test the effectiveness of the chemical defences of the wood tiger moth, a species previously shown to have defensive chemicals targeted towards ants, against a common invertebrate predator: spiders. We presented both live moths and artificial prey containing their defensive fluids to female Trichonephila senegalensis and recorded their reactions. We found that neither of the moth’s two defensive fluids were able to repel the spiders, and confirmed that methoxypyrazines, a major component of the defences of both the wood tiger moth and many insect species, are ineffective against web-building spiders. Our results highlight the variability between predator taxa in their susceptibility to chemical defences, which can in part explain the vast variation in these chemicals seen in insects, and the existence of multiple defences in a single species.

Debris dams as habitat for aquatic invertebrates in forested headwater streams: a large-scale field experiment

2019 ◽  
Vol 70 (5) ◽  
pp. 734
Author(s):  
Brenda R. Baillie ◽  
Brendan J. Hicks ◽  
Ian D. Hogg ◽  
Michael R. van den Heuvel ◽  
Mark O. Kimberley
Keyword(s):  
Large Scale ◽  
Aquatic Invertebrates ◽  
Headwater Streams ◽  
Dam Removal ◽  
Aquatic Invertebrate ◽  
Invertebrate Communities ◽  
Debris Dams ◽  
Scale Field ◽  
Large Scale Field ◽  
Debris Dam

To evaluate the effects of debris dams on aquatic invertebrate communities, we sampled benthic invertebrates in debris dams and riffles in three forested headwater streams in New Zealand. As part of a large-scale field experiment, debris dams were subsequently removed from three treatment sections in each of the streams to assess effects on invertebrate communities. Prior to debris dam removal, total invertebrate densities in debris dams were not significantly different from those in riffles. However, densities of Ephemeroptera, Plecoptera and Trichoptera taxa were significantly higher in debris dams than in riffles. Debris dams contained a higher number of less common taxa (defined as <1% of total catch) and significantly higher densities of shredders. Densities for Coleoptera, Diptera and Trichoptera taxa were significantly higher in the autumn than in the spring. Non-metric multidimensional scaling axis scores indicated that both habitat and season had a significant effect on aquatic invertebrate community composition. At the reach scale, the effects of debris dam removal on the aquatic invertebrate communities were not statistically detectable because debris dams comprised only a small proportion of total habitat. However, these data highlight the importance of debris dams in contributing to the diversity of aquatic invertebrates in forested headwater streams.

Effects of gear type, entrance size and soak time on trap efficiency for freshwater crayfish Cherax destructor and C. albidus

2015 ◽  
Vol 66 (11) ◽  
pp. 989
Author(s):  
Paul Brown ◽  
Taylor L. Hunt ◽  
Khageswor Giri
Keyword(s):  
Field Experiments ◽  
Freshwater Crayfish ◽  
Recreational Fisheries ◽  
Air Breathing ◽  
Fixed Ring ◽  
Cherax Destructor ◽  
Fishing Gears ◽  
Opera House ◽  
By Catch ◽  
Aquatic Mammals

Freshwater crayfish support significant commercial and recreational fisheries worldwide. The genus Cherax is fished in Australia with a variety of fishing gears, yet little is known of the relative efficiency of the different fishing gears and methods. Additionally, freshwater-crayfish traps can pose a risk to air breathing by-catch such as aquatic mammals, reptiles and birds, so by-catch mitigation is important. We sought to understand whether freshwater-crayfish fishing can be undertaken efficiently, using passive traps and nets, without undue risk to air-breathing by-catch species. In field-experiments, we compared the efficiency of six gear types and tested the effect of five exclusion rings on catch performance over three soak times. The efficiency of gear types varied significantly by soak times. In productive locations, catch can be maximised by repeatedly deploying open-topped gear for short soak times. Opera-house traps fitted with fixed entrance rings (45–85-mm diameter) were not size-selective for yabbies. Encouragingly, open-topped gear and opera-house traps fitted with fixed ring entrances much smaller than many commercially available (45-mm diameter) still fish effectively for yabbies. We believe that smaller fixed ring-entrance size is likely to be correlated with a reduced risk of by-catch for air-breathing fauna.

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