Aggressive interactions between three species of freshwater crayfish of the genus Cherax (Decapoda: Parastacidae)

The freshwater crayfish, Cherax destructor Clark, native to southeastern Australia, was first introduced to farm dams in southwestern Western Australia in 1932. The geographic range of the crayfish in Western Australia has increased substantially since then, and in recent years it has become established in natural waterways where it co-occurs with species of freshwater crayfish endemic to southwestern Australia, Cherax cainii and Cherax quinquecarinatus. The potential for competitive exclusion of these endemic species by C. destructor was investigated through laboratory experiments measuring aggressive behaviour. Body mass and species were found to be important factors governing aggressive dominance between C. cainii and C. destructor, with C. cainii winning significantly more interactions only when they were larger in body mass than their opponent. In trials between C. quinquecarinatus and C. destructor of similar body mass, there was no difference between the number of interactions 'won' by the two species. The implications for natural populations are discussed.     

Testing Phylogenetic Hypotheses of the Subgenera of the Freshwater Crayfish Genus Cambarus (Decapoda: Cambaridae)

Background

The genus Cambarus is one of three most species rich crayfish genera in the Northern Hemisphere. The genus has its center of diversity in the Southern Appalachians of the United States and has been divided into 12 subgenera. Using Cambarus we test the correspondence of subgeneric designations based on morphology used in traditional crayfish taxonomy to the underlying evolutionary history for these crayfish. We further test for significant correlation and explanatory power of geographic distance, taxonomic model, and a habitat model to estimated phylogenetic distance with multiple variable regression.

Methodology/Principal Findings

We use three mitochondrial and one nuclear gene regions to estimate the phylogenetic relationships for species within the genus Cambarus and test evolutionary hypotheses of relationships and associated morphological and biogeographical hypotheses. Our resulting phylogeny indicates that the genus Cambarus is polyphyletic, however we fail to reject the monophyly of Cambarus with a topology test. The majority of the Cambarus subgenera are rejected as monophyletic, suggesting the morphological characters used to define those taxa are subject to convergent evolution. While we found incongruence between taxonomy and estimated phylogenetic relationships, a multiple model regression analysis indicates that taxonomy had more explanatory power of genetic relationships than either habitat or geographic distance.

Conclusions

We find convergent evolution has impacted the morphological features used to delimit Cambarus subgenera. Studies of the crayfish genus Orconectes have shown gonopod morphology used to delimit subgenera is also affected by convergent evolution. This suggests that morphological diagnoses based on traditional crayfish taxonomy might be confounded by convergent evolution across the cambarids and has little utility in diagnosing relationships or defining natural groups. We further suggest that convergent morphological evolution appears to be a common occurrence in invertebrates suggesting the need for careful phylogenetically based interpretations of morphological evolution in invertebrate systematics.     

Effect of the protein level in the diet on the development of young Australian lobsters, Cherax quadricarinatus (Decapoda: Parastacidae)

An experimental study was conducted from October to December, 1999, in the aquaculture facilities of CIBNOR SC, at La Paz, BCS. To evaluate the effect of diet protein level on the productive response, in juveniles of the australian lobster, Cherax quadricarinatus, diets with four levels of crude protein (20.45, 28.25, 37.33 y 45.44%), were formulated and probed. Growth, grow rate, survival, biomass and food conversion rate were greater in juveniles fed with diets of 37.33 and 45.44% of crude protein. It is concluded that diet protein level affects the productive response of redclaw and a level of 37% of crude protein in the diet is enough to obtain acceptable results.     

Vitellogenin levels in hemolymph, ovary and hepatopancreas of the freshwater crayfish Cherax quadricarinatus (Decapoda: Parastacidae) during the reproductive cycle

The freshwater crayfish Cherax quadricarinatus is a tropical species of great interest for aquaculture. Vitellogenin (Vg), a lipoprotein precursor of the vitellum accumulated in spawned eggs, can be synthesized in the ovary and/or hepatopancreas of most crustaceans, being the hemolymph the way for transporting Vg throughout the reproductive cycle. Concentration of Vg in hemolymph, ovary and hepatopancreas of Cherax quadricarinatus adult females was measured by means of ELISA, specifically developed after purifying the native Vg. Measurements were made at four periods of the reproductive cycle: pre-reproductive, mid-reproductive, late reproductive and post-reproductive. Besides, both hepatosomatic (HSI) and gonadosomatic (GSI) indexes were determined in each period. Significant variations in Vg levels were detected in both hemolymph and hepatopancreas, being the highest values observed during the mid-reproductive period. Besides, such variations were positively correlated to the HSI. A positive correlation between Vg levels in hepatopancreas and ovary was also seen. These results support previous evidences about the central role of the hepatopancreas as a site of Vg synthesis in the studied species, together with the relevancy of hemolymph for transporting Vg from the hepatopancreas to the ovary. For aquaculture purposes, Vg monitoring in hemolymph could be used as a non-injurious method, to check the reproductive activity of C. quadricarinatus females.     

Structural changes in the spermatophore of the freshwater 'red claw' crayfish Cherax quadricarinatus (Von Martens, 1898) (Decapoda, Parastacidae)

López Greco, L.S. and Lo Nostro, F.L. 2007. Structural changes in the spermatophore of the freshwater ‘red claw’ crayfish Cherax quadricarinatus (Von Martens, 1898) (Decapoda, Parastacidae). —Acta Zoologica (Stockholm) 88 : 000–000 The structure of the spermatophore was studied in Cherax quadricarinatus. Pieces of the distal vas deferens and transferred spermatophore from the females were fixed, cut and stained. Within the distal vas deferens, the primary layer and the secondary layer of the spermatophore were distinguishable. In the latter, two components were detected: cytoplasmic droplets and a homogeneous matrix. During the first 10 minutes post‐extrusion the cytoplasmic droplets drastically changed from looking like ‘empty droplets’; at this time the spermatophore changed from a liquid stage to a sticky one. One hour after extrusion the spermatophore began to harden and within the first 24–48 h post‐mating it was a solid and intense white structure tightly attached to the female; after 72 h it acquired a softer aspect, completely dehiscing between 96 and 120 h post‐mating. Histologically, the primary layer maintained its integrity surrounding the spermatozoa while the secondary layer lost the cytoplasmic droplets. The spermatophore began to hydrate between 24 and 48 h and by 72–96 h many sections of the sperm cord began to coalesce. From 48 h post‐mating some fissures appeared within the matrix that enlarged between 72 and 120 h. We propose that both manipulation by the female and hydration are the mechanisms involved in the release of the spermatozoa from the spermatophore.     

Amplification of multiple copies of mitochondrial Cytochrome b gene fragments in the Australian freshwater crayfish,Cherax destructor Clark (Parastacidae: Decapoda)

Non-coding copies of fragments of the mitochondrial genome translocated to the nucleus or pseudogenes are being found with increasing frequency in a diversity of organisms. As part of a study to evaluate the utility of a range of mitochondrial gene regions for population genetic and systematic studies of the Australian freshwater crayfish, Cherax destructor (the yabby), we report the first detection of Cytochrome b (Cyt b) pseudogenes in crustaceans. We amplified and sequenced fragments of the mitochondrial Cyt b gene from 14 individuals of C. destructor using polymerase chain reaction (PCR) with primers designed from conserved regions of Penaeus monodon and Drosophila melanogaster mitochondrial genomes. The phylogenetic tree produced from the amplified fragments using these primers showed a very different topology to the trees obtained from sequences from three other mitochondrial genes, suggesting one or more nuclear pseudogenes have been amplified. Supporting this conclusion, two highly divergent sequences were isolated from each of two single individuals, and a 2 base pair (bp) deletion in one sequence was observed. There was no evidence to support inadvertent amplification of parasite DNA or contamination of samples from other sources. These results add to other recent observations of pseudogenes suggesting the frequent transfer of mitochondrial DNA (mtDNA) genes to the nucleus and reinforces the necessity of great care in interpreting PCR-generated Cyt b sequences used in population or evolutionary studies in freshwater crayfish and crustaceans more generally.     

Direct Age Determination of a Subtropical Freshwater Crayfish (Redclaw,Cherax quadricarinatus) Using Ossicular Growth Marks

Recent studies have reported that crustacean age determination is possible. We applied a direct ageing method (i.e. transverse cross sectioning of gastric ossicles) to a subtropical freshwater crayfish (Cherax quadricarinatus) sourced from an aquaculture population. Growth mark periodicity and the potential for chronological depositions were investigated by staining C. quadricarinatus with calcein and examining their ossicles a year later. Pterocardiac ossicles were superior to other ageing structures (i.e. other ossicles and eyestalks) and produced repeatable between-reader counts (87% were corroborated and 13% varied by ±1). C. quadricarinatus size-at-age data (for an aquaculture population) was described by a von Bertalanffy growth equation (L _∞ = 32 mm occipital carapace length; K = 0.64; t ₀ = –0.18; R² = 0.81). Ossicular growth marks did not correspond to moult history. The calcein stain was retained over an annual cycle comprising multiple moults, demonstrating that pterocardiac ossicles retain chronological information. The maximum age (3+) corroborated other indirectly-obtained longevity estimates for C. quadricarinatus. Multiple lines of evidence indicate that the growth marks in C. quadricarinatus ossicles are probably deposited annually during winter. The ability to extract age information from subtropical decapods provides substantial opportunities for advancing fisheries and conservation research globally, but further research is needed to provide a definitive validation and elucidate the mechanism governing the accrual of ossicular growth marks.     

Morphology of the male reproductive system and spermatophore formation in the freshwater 'red claw' crayfish Cherax quadricarinatus (Von Martens, 1898) (Decapoda, Parastacidae)

The morphology of the male reproductive system was studied in Cherax quadricarinatus. The testes and vasa deferentia were dissected, fixed, cut and stained. Testes appear as two parallel and opalescent strands; they present many testicular lobes, each lobe containing cells in the same stage of the spermatogenic cycle. A vas deferens arises from the external side of each testis and three parts were clearly distinguished: proximal vas deferens (PVD), middle vas deferens (MVD) and distal vas deferens (DVD). The PVD is opalescent and highly convoluted, the MVD is pale white in colour and convoluted, but wider in diameter than the PVD, while the DVD shows the widest diameter, is straight and is white in colour. A single‐layered epithelium is recognized in the vas deferens; with cylindrical cells in the PVD and cuboid cells in the MVD and DVD. The formation of the spermatophore starts at the PVD, while the secondary layer of the spermatophore seems to be added at the MVD. At the DVD, the highly coiled spermatophore is surrounded by the periodic acid Schiff‐positive sticky components of the secondary layer. Many aspects of spermatophore formation in C. quadricarinatus differ from those of other Astacida. The applied aspects of this study for aquaculture purposes are discussed.     

Phylogeny and Evolutionary Patterns in the Dwarf Crayfish Subfamily (Decapoda: Cambarellinae)

The Dwarf crayfish or Cambarellinae, is a morphologically singular subfamily of decapod crustaceans that contains only one genus, Cambarellus. Its intriguing distribution, along the river basins of the Gulf Coast of United States (Gulf Group) and into Central México (Mexican Group), has until now lacked of satisfactory explanation. This study provides a comprehensive sampling of most of the extant species of Cambarellus and sheds light on its evolutionary history, systematics and biogeography. We tested the impact of Gulf Group versus Mexican Group geography on rates of cladogenesis using a maximum likelihood framework, testing different models of birth/extinction of lineages. We propose a comprehensive phylogenetic hypothesis for the subfamily based on mitochondrial and nuclear loci (3,833 bp) using Bayesian and Maximum Likelihood methods. The phylogenetic structure found two phylogenetic groups associated to the two main geographic components (Gulf Group and Mexican Group) and is partially consistent with the historical structure of river basins. The previous hypothesis, which divided the genus into three subgenera based on genitalia morphology was only partially supported (P = 0.047), resulting in a paraphyletic subgenus Pandicambarus. We found at least two cases in which phylogenetic structure failed to recover monophyly of recognized species while detecting several cases of cryptic diversity, corresponding to lineages not assigned to any described species. Cladogenetic patterns in the entire subfamily are better explained by an allopatric model of speciation. Diversification analyses showed similar cladogenesis patterns between both groups and did not significantly differ from the constant rate models. While cladogenesis in the Gulf Group is coincident in time with changes in the sea levels, in the Mexican Group, cladogenesis is congruent with the formation of the Trans-Mexican Volcanic Belt. Our results show how similar allopatric divergence in freshwater organisms can be promoted through diverse vicariant factors.     

Effect of temperature on lipids,proteins, and carbohydrates levels during development from egg extrusion to juvenile stage of Cherax quadricarinatus (Decapoda: Parastacidae)

The influence of temperature on biochemical composition, survival and duration of development of Cherax quadricarinatus from egg extrusion to juvenile was analyzed. Berried females were individually subjected to each of 22, 25, 28 and 31 degrees C (n=5 per temperature). Egg samples were obtained every 3 days from egg extrusion to juvenile stage for biochemical analysis. Duration of development and survival decreased with increasing temperature. At 22 and 25 degrees C half of the initial lipid content was consumed during development. At 28 and 31 degrees C, 80% of the initial amount of lipids was consumed. For proteins, depletion rate was significantly lower at 25 degrees C (36% of the initial amount) than at 22, 28 and 31 degrees C (61-65% of the initial amount). For carbohydrates, a significant consumption was observed only at 22 degrees C. Total energy consumption was lower at 22 and 25 degrees C than at 28 and 31 degrees C. We conclude that 22-25 degrees C is the optimal temperature range for C. quadricarinatus egg incubation, although 25 degrees C might be better in terms of development duration in terms of survival, energy cost and protein consumption.     

Camera Trap Observations of Nonhabituated Critically Endangered Wild Blonde Capuchins,Sapajus flavius (Formerly Cebus flavius)

Habituation presents major challenges for the study of wild primates, particularly in areas where threats such as hunting pressure and increasing forest fragmentation exist. This study describes the use of ground camera trapping to investigate nonhabituated blonde capuchins. Capuchins are arboreal animals, but often use the ground when foraging. Thus, we hypothesized that a ground-baited camera trapping station would be an efficient method to document the presence of capuchins, and to collect information about aspects of their social behavior and ecology. We conducted 92 systematic trapping days over 15 months (from December 2010 to February 2011 and from August 2011 to July 2012). The capuchins visited the trapping stations 43 times. All visits occurred between 05:13h and 17:32h, and lasted 3 min-2:03 h. Sixty-five percent of the photographs included our target species. Groups contained up to 46 individuals and were multimale-multifemale. We recorded no monkeys at the trapping stations during August and November (2011) and January (2012). Infants were more likely to be carried than not. Infants were carried by both sexes; however, 96% of photographs showed females as carriers. Adult males always arrived first at the camera trapping stations, suggesting that males led the group’s movements. The ground-baited camera trapping stations proved effective for confirming the presence of the blonde capuchins in the study site and for documenting aspects of their social behavior. The technique could potentially be used to provide comparative data among populations of this and other primate species in areas where habituation is difficult or risky to the primates.     

Seasonal variations in the intermediate metabolism of Parastacus varicosus (Crustacea, Decapoda, Parastacidae)

The aim of this study was to analyze the seasonal variations in the metabolism of Parastacus varicosus and examine the possible relationships to its reproduction. Animals were sampled (9 h to 10 h) in each month in the Gravataí River, RS, Brazil. Haemolymph samples were collected from each crayfish in the field for determination of glucose, total proteins, total lipids, and total cholesterol. Hepatopancreas, abdominal muscle, and gonads were removed for determination of glycogen, total proteins, total lipids, and total cholesterol. ANOVA revealed significant seasonal differences in the biochemical composition of all tissues studied; when the sexes were compared these parameters did not show any significant difference in the hepatopancreas and muscle. However, in haemolymph we observed significant variation only in cholesterol and lipid levels. The results suggest that the metabolic variability is related to the stage of maturation of the gonads, in females, where the hepatopancreas and other tissue studies can store and transfer reserves to support maturation to complement the food intake. Variations in the gonadosomatic and hepatosomatic indices suggest that reproduction occurs principally in summer. As in other decapods, abiotic factors such as water temperature, oxygen content, etc. influence the intermediate metabolism.     

Cherax (Astaconephrops) pulcher,a new species of freshwater crayfish (Crustacea,Decapoda, Parastacidae) from the Kepala Burung (Vogelkop) Peninsula,Irian Jaya (West Papua), Indonesia

A new species, Cherax (Astaconephrops) pulcher sp. n., from Hoa Creek, close to the village Teminabuan in the southern-central part of the Kepala Burung (Vogelkop) Peninsula, West Papua, Indonesia, is described, figured and compared with the morphologically closest species, Cherax boesemani Lukhaup & Pekny, 2008.     

Ultrastructural characteristics and small subunit ribosomal DNA sequence of Vairimorpha cheracis sp. nov., (Microspora: Burenellidae), a parasite of the Australian yabby, Cherax destructor (Decapoda: Parastacidae)

This is the first record of a species of Vairimorpha infecting a crustacean host. Vairimorpha cheracis sp. nov. was found in a highland population of the Australian freshwater crayfish, Cherax destructor. The majority of spores and earlier developmental stages of V. cheracis sp. nov. were found within striated muscle cells of the thorax, abdomen, and appendages of the crayfish. Only octosporoblastic sporogony within sporophorous vesicles (SPVs) was observed. Diplokaryotic sporonts separated into two uninucleate daughter cells, each of which gave rise to four sporoblasts in a rosette-shaped plasmodium, so that eight uninucleate spores were produced within the persistent ovoid SPV. Ultrastructural features of stages in the octosporoblastic sequence were similar to those described for Vairimorpha necatrix, the type species. Mature spores were pyriform in shape and averaged 3.4x1.9 microm in dimensions. The anterior polaroplast was lamellar in structure, and the posterior polaroplast vesicular. The polar filament was coiled 10-12 times, lateral to the posterior vacuole. The small subunit ribosomal DNA (SSU rDNA) of V. cheracis sp. nov. was sequenced and compared with other microsporidia. V. cheracis sp. nov. showed over 97% sequence identity with Vairimorpha imperfecta and five species of Nosema, and only 86% sequence identity with V. necatrix. The need for a taxonomic revision of the Nosema/Vairimorpha group of species is discussed.     

In vitro effects of both dopaminergic and enkephalinergic antagonists on the ovarian growth of Cherax quadricarinatus (Decapoda, Parastacidae), at different periods of the reproductive cycle

The in vitro effect of both spiperone (dopaminergic antagonist) and naloxone (enkephalinergic antagonist), was assayed on small pieces of ovary dissected from C. quadricarinatus females, with the eventual addition of some neuroendocrine organs, such as thoracic ganglion or eyestalk tissue. The incorporation of tritiated leucine by the ovary was measured in order to estimate the ovarian growth. During the post-reproductive period, both mentioned antagonists were able to significantly stimulate the ovary in the presence of thoracic ganglion, but did not produce any significant effect in the preparation containing ovary and eyestalk tissue, or only ovary. No significant effects of the assayed antagonists were noted during the pre-reproductive period. These results were in accordance with previous models describing the neuroendocrine control of crustacean reproduction, and represent new findings about the hormonal context in different periods of the reproductive cycle of crayfish. Besides, by means of the experimental combination of the tested antagonists with dopamine or met-enkephalin, a new model dealing with the interaction of these two neurotransmitters on the hormonal secretion of thoracic ganglion has been proposed.     

Micropropagation of Withania coagulans (Stocks) Dunal: A Critically Endangered Medicinal Herb

An efficient micropropagation protocol has been developed for Withania coagulans, a highly endangered medicinal herb and an important natural source of withanolides. Prolific multiplication of axillary buds occurred from the nodal segments taken from adult plant, and cultured on MS medium enriched with BA (0.5 mg l^?1), Kn (0.5 mg l^?1) and PG (0.5 mg l^?1). Nodal segments and shoot tips of elongated microshoots also behaved the same way in cultures and formed multiple shoots through axillary bud multiplication. Addition of PG (0.5 mg l^?1) in the regeneration medium significantly improved induction and elongation of shoot buds. Elongated shoots were placed on filter paper bridges soaked in MS medium with CC (10 mg l^?1) and PG (0.5 mg l^?1) for the initial 7 days’ pulse treatment and thereafter, they were transferred to rooting medium containing IBA (0.25 mg l^?1) + PAA (0.5 mg l^?1) + CC (2 mg l^?1). This protocol has the capacity of producing 1000 plants from one nodal segment after 4 subcultures of 2 weeks each.     

The Molecular Evolution of Visual Pigments of Freshwater Crayfishes (Decapoda: Cambaridae)

This study examines the diverse maximum wavelength absorption (λ_max) found in crayfishes (Decapoda: Cambaridae and Parastacidae) and the associated genetic variation in their opsin locus. We measured the wavelength absorption in the photoreceptors of six species that inhabit environments of different light intensities (i.e., burrows, streams, standing waters, and subterranean waters). Our results indicate that there is relatively little variation in λ_max (522–530 nm) among species from different genera and families. The existing variation did not correlate with the habitat differences of the crayfishes studied. We simultaneously sequenced the rhodopsin gene to identify the amino acid replacements that affect shifts in maximum wavelength absorption. We then related these to changes that correlated with shifts in λ_max by reconstructing ancestral character states using a maximum-likelihood approach. Using amino acid sequences obtained from five species (all were 301 amino acids in length), we identified a number of candidates for producing shifts of 4 to 8 nm in λ_max. These amino acid replacements occurred in similar regions to those involved in spectral shifts in vertebrates. Received: 12 March 1997 / Accepted: 3 June 1997     

Compensatory Growth in Juveniles of Freshwater Redclaw Crayfish Cherax quadricarinatus Reared at Three Different Temperatures: Hyperphagia and Food Efficiency as Primary Mechanisms

Feeding restriction, as a trigger for compensatory growth, might be considered an alternative viable strategy for minimizing waste as well as production costs. The study assessed whether juvenile redclaw crayfish Cherax quadricarinatus (initial weight 0.99 ±0.03 g) was able to compensate for feeding restriction at different temperatures (23±1, 27±1 and 31±1°C). Hyperphagia, food utilization efficiency, energetic reserves, and hepatopancreas structure were analyzed. Three temperatures and two feeding regimes (DF-daily fed throughout the experiment and CF- 4 days food deprivation followed by 4 days of feeding, intermittently) were tested. The restriction period was from day 1 to 45, and the recovery period was from day 45 to 90. The previously restricted crayfish held at 23, 27, and 31 ± 1°C displayed complete body weight catch-up through compensatory growth following the restriction period with depressed growth. The mechanisms that might explain this response were higher feed intake (hyperphagia), and increased food utilization efficiency. Hepatopancreatic lipids were used as a metabolic fuel and hepatosomatic index was reduced in the previously restricted crayfish, but recovery at the same level of unrestricted crayfish occurred after the shift to daily feeding. The highest temperature affected adversely growth, feed intake, food efficiency, and metabolism of crayfish, whereas the lowest temperature and feeding restriction induced a more efficient growth of the crayfish.     

Diverse grouping and mating strategies in the Critically Endangered Hainan gibbon (Nomascus hainanus)

Primates - Understanding flexibility in the social structure and mating strategies of the world’s last remaining population (35 individuals) of wild Hainan gibbons (Nomascus hainanus) is...