Captive Freshwater Research Articles

Hematology and blood biochemistry profile of the freshwater stingray Potamotrygon magdalenae as a tool for population assessment in artificial environments.

Hematological and blood biochemical reference information is important to establish physiological status of freshwater stingray populations and improve care and management protocols in artificial environments. Here, we used a commercial freshwater stingray with high mortality rates in the market (Potamotrygon magdalenae), as an example to understand how artificial environments and handling protocols influence physiological status of captive freshwater stingrays. To this purpose, blood from five adult males and six adult females was collected to perform complete blood counts and blood chemistry analyses. All sampled animals showed good body condition with no differences between sexes. Differences between sexes were only found for the differential count of lymphocytes. Red blood results were consistent with previously studied potamotrygonids while white blood results showed higher values of leukocytes, thrombocytes, heterophils and lymphocytes in P. magdalenae compared to other Potamotrygonids. All types of leukocytes described for elasmobranchs were found except neutrophils and basophils. Blood metabolites showed an influence of ex situ diet in total protein, triglycerides and cholesterol. Glucose results were consistent while urea showed lower levels than those recorded for other freshwater stingrays. These results highlight the importance of physical, physiological and health analysis in freshwater stingrays as a part of welfare assessment to improve monitoring protocols and survival rates in public or private aquaria.

Interest in coloured objects and behavioural budgets of individual captive freshwater turtles

Interest in coloured objects and behavioural budgets of individual captive freshwater turtles

Comparative analysis of noise effects on wild and captive freshwater fish behaviour

Anthropogenic noise is globally increasing in aquatic ecosystems and causes adverse repercussions in many fish species, yet its effect on freshwater fish is not well understood. Here, we test the impact of boat noise on foraging and swimming behaviour on a number of wild freshwater fish species as well as captive black bullhead, Ameiurus melas, a common species in the Laurentian Great Lakes with known hearing specializations. In a laboratory setting, black bullhead were exposed to white noise, boat noise and a quiet control and monitored for changes in foraging behaviours and swimming patterns when presented with food. Black bullhead exposed to both boat noise and white noise foraged less and startled more in comparison to trials without noise. In a field setting, wild fishes with differing hearing capabilities were exposed to boat noise and a quiet control, then analysed for changes in both presence and foraging behaviour when presented with food. Field experiments were consistent with results from our laboratory study, resulting in decreased presence of wild fish and fewer foraging attempts made during boat noise exposure. However, the effects of noise in the field were highly variable by family, with fish in the Cyprinidae (or Leuciscidae) family, all of which have Weberian ossicle hearing specializations, exhibiting significantly larger decreases in feeding events and presence compared to other families (Gobiidae, Percidae and Centrarchidae) with more basic hearing abilities. Freshwater fishes alter their foraging behaviour during noise exposure, however, variation in hearing abilities may determine the extent to which their behaviour changes and the resulting degree of negative consequences.

内陸県におけるアマゾン産淡水エイによる刺傷の1例(A case of injury due to a sting by a captive freshwater stingray in an inland region)

要旨症例は患者が飼育中のアマゾン産淡水エイPotamotrygon leopoldiの水替え中に手背を刺されて来院したもので，刺傷後から疼痛が激しく，創部の洗浄と消毒に加え，海産エイ毒の解毒方法に準じて40℃の湯に創部を浸漬したところ，疼痛の軽減を図ることができた。その後，疼痛が数日の間は継続したが，広範な壊死を来すことはなく細菌感染などの併発もなく治癒した。エイ毒は複数の蛋白毒で構成され，疼痛・腫脹・壊死を来すほか，ショック症状・呼吸困難を来し，ときに死に至ることもある。一部の海産タンパク毒と同様に高温に弱く，患部を温水に浸漬することで症状を軽減できるといわれるが，種差・性差・成熟度による毒性・毒量を含めて不明な点が多い。本邦では淡水エイによる刺傷の報告が少なく，今回の症例のように後遺症を認めずに治癒する症例がある一方で，後遺症や手術を要した症例も報告されている。淡水エイの毒性については不確定なことが多く，症例および治療経験の蓄積が重要であると考えられた。

The effects of broodstock generation on ova fatty acid profile in Giant Kokopu Galaxias argenteus

ABSTRACT The ability of different broodstock generations to provision lipids to their gametes is often overlooked in aquacultured freshwater fish. In this study we investigated the ability of two generations (F1 & F2) of Giant Kokopu (Galaxias argenteus) to provision fatty acids into their eggs. Here we show that eggs of captive-bred females (F2) displayed different relative fatty acid concentrations compared with eggs of females bred from wild fish (F1). F2 generation eggs showed significantly lower total mono unsaturated fatty acids (MUFA) concentration, predominantly through lower C18:1(n−9) Oleic acid, and higher total poly unsaturated fatty acids (PUFA) concentration, predominantly through higher 22:6(n−3) docosahexaenoic acid [DHA]. Furthermore, Oleic to n−3 fatty acid ratio, and Oleic to DHA ratio, both declined significantly from F1 to F2 generation. Our results suggest an elevated capacity of F2 females to provision better ratios of essential fatty acids during reproduction, most likely due to a transgenerational adaptive response, either to the fed diet or to a predictable laboratory environment. The findings of this study have important implications for aquaculture management in new captive freshwater species, particularly in aiding identification of more adapted broodstock generations.

Hematological and Biochemical Assessment of Two Species of Freshwater Mussels, Quadrula quadrula and Amblema plicata, Following Translocation.

Nondestructive, sublethal, and sensitive health monitoring tools are needed to assess the health of freshwater mussels (family Unionidae). Recent developments to standardize hemocyte characterization have assisted in the hematologic assessment of wild and captive freshwater mussels. In this study, preliminary baseline hematological reference ranges were established for wild mapleleaf mussels Quadrula quadrula (n=14) and threeridge mussels Amblema plicata (n=20) collected from the Muskingum River in Devola, Ohio. Mussels were collected from the wild, and hemolymph was sampled from each mussel in the field upon capture (baseline sample). They were then transported live to a propagation facility. Subsequent hemolymph samples were collected at 2 and 4weeks and quarterly thereafter for 11months following translocation. Hemocyte counts, hemocyte morphology, and hemolymph chemistry (Na+ , Cl- , Mg2+ , P3- , K+ , Ca2+ , glucose, alanine aminotransferase, aspartate aminotransferase, and alkaline phosphatase]) were measured from each sample on each sampling occasion. Hemocyte counts were consistently greater in Q. quadrula than in A. plicata following transfer to captivity. Baseline hemocyte morphology and hemolymph chemistry varied between species. This study provides a foundation of reference ranges for hemocyte characterization for Q. quadrula, and A. plicata and a preliminary understanding of how hemocyte character might be expected to change when wild mussels are translocated into captivity, and thus be a useful technique for monitoring the health of freshwater mussels.

Molecular identification of three novel herpesviruses found in Australian farmed saltwater crocodiles (Crocodylus porosus) and Australian captive freshwater crocodiles (Crocodylus johnstoni)

As part of a larger investigation into three emerging disease syndromes highlighted by conjunctivitis and pharyngitis, systemic lymphoid proliferation and encephalitis, and lymphonodular skin infiltrates in farmed saltwater crocodiles (Crocodylus porosus) and one emerging syndrome of systemic lymphoid proliferation in captive freshwater crocodiles (Crocodylus johnstoni), cytopathic effects (CPE), including syncytial cell formation, were observed in primary crocodile cell lines exposed to clarified tissue homogenates from affected crocodiles. Ten cell cultures with CPE were then screened for herpesviruses using two broadly-reactive herpesvirus PCRs. Amplicons were obtained from 9 of 10 cell cultures and were sequenced. Three novel herpesviruses were discovered and the phylogenetic analysis of these viruses showed there was a 63% Bayesian posterior probability value supporting these viruses clustering with the subfamily Alphaherpesvirinae, and 100% posterior probability of clustering with a clade containing the Alphaherpesvirinae and other unassigned reptile herpesviruses. It is proposed that they are named Crocodyline herpesvirus (CrHV) 1, 2 and 3. CrHV1 and 2 were only isolated from saltwater crocodiles and CrHV3 was only isolated from freshwater crocodiles. A duplex PCR was designed that was able to detect these herpesviruses in formalin-fixed paraffin-embedded tissues, a sample type that neither of the broadly-reactive PCRs was able to detect these herpesviruses in. This work describes the isolation, molecular detection and phylogeny of these novel herpesviruses but the association that they have with the emerging disease syndromes requires further investigation.

Encephalitozoon hellem Infection in a Captive Juvenile Freshwater Crocodile (Crocodylus johnstoni)

Microsporidiosis is reported rarely in reptiles and has never been reported in any species of crocodilian. Microsporidiosis was diagnosed histologically in a juvenile captive freshwater crocodile (Crocodylus johnstoni) that was found suddenly dead in its enclosure. Ultrastructural and molecular testing revealed infection to be due to Encephalitozoon hellem. This is the first report of E. hellem infection in any species of reptile.

Invasive species threat: parasite phylogenetics reveals patterns and processes of host-switching between non-native and native captive freshwater turtles

One of the major threats to biodiversity involves biological invasions with direct consequences on the stability of ecosystems. In this context, the role of parasites is not negligible as it may enhance the success of invaders. The red-eared slider, Trachemys scripta elegans, has been globally considered among the worst invasive species. Since its introduction through the pet trade, T. s. elegans is now widespread and represents a threat for indigenous species. Because T. s. elegans coexists with Emys orbicularis and Mauremys leprosa in Europe, it has been suggested it may compete with the native turtle species and transmit pathogens. We examined parasite transfer from American captive to the two native species that co-exist in artificial pools of a Turtle Farm in France. As model parasite species we used platyhelminth worms of the family Polystomatidae (Monogenea) because polystomes have been described from American turtles in their native range. Phylogenetic relationships among polystomes parasitizing chelonian host species that are geographically widespread show patterns of diversification more complex than expected. Using DNA barcoding to identify species from adult and/or polystome eggs, several cases of host switching from exotic to indigenous individuals were illustrated, corroborating that parasite transmission is important when considering the pet trade and in reintroduction programmes to reinforce wild populations of indigenous species.

Native or not? Tracing the origin of wild-caught and captive freshwater turtles in a threatened and widely distributed species (Emys orbicularis)

Pet and food trade are among the major threats for many chelonians species worldwide. We investigate the impact of the present and past trade in European pond turtles (Emys orbicularis, E. trinacris) on their extant distribution pattern. Using a comprehensive mtDNA dataset of cytochrome b haplotypes derived from more than 1,550 individuals, we assigned wild-caught allochthonous and captive turtles from six European countries to their native regions across the entire distribution range. We found allochthonous haplotypes in all countries surveyed, providing evidence of long-distance translocations owing to past and present trade, illegal poaching or collection by tourists. In summary, we identify source regions of allochthonous turtles and past and present trade routes. Moreover, we point out future directions which would contribute to conservation and management of these threatened species.

Two generations of outbreeding in coho salmon (Oncorhynchus kisutch): effects on size and growth

Outbreeding is a potential genetic risk in Pacific salmon (Oncorhynchus spp.) when aquaculture practices introduce nonnative domesticated fish to wild environments, making interbreeding with wild populations possible. In this study, F1 and F2 hybrid families of coho salmon (Oncorhynchus kisutch) were created using a captive freshwater aquaculture strain and a locally derived hatchery population that is integrated with naturally spawning fish. Intermediate growth was detected in F1 and F2 hybrids from crosses reared in captivity; both generations had mean weight and length values between those of the parent populations after their first year (p < 0.05). In the early life history stages, maternal effects increased alevin growth in progeny of hatchery dams relative to those of captive dams (p < 0.001). Aquaculture control families showed greater growth rates than hybrids in late summer of their 1st year and in the following spring (p < 0.05), while the hatchery controls had lower growth rates during the first summer (p < 0.05). Line cross analysis indicated that changes in additive and dominance interactions, but not unfavorable epistatic interactions, likely explain the differences in weight, length, and growth rate observed in hybrids of these stocks of coho salmon.

Myxidium mackiei (Myxosporea) in Indo-Gangetic flap-shelled turtles Lissemys punctata andersonii: parasite-host interaction and ultrastructure

Myxosporeans are common parasites of fish, and uncommon parasites of amphibians, reptiles and invertebrates, that can cause significant morbidity and mortality. The common genus Myxidium infects the excretory system of turtles, yet knowledge of its pathogenicity in these hosts is limited. We offer new knowledge of morphological and ultrastructural aspects of host-parasite interactions in Myxidium infections from our recent diagnostic investigations on captive freshwater turtles listed in CITES (Appendix II). We investigated the cause of death of 2 adult Indo-Gangetic flap-shelled turtles Lissemys punctata andersonii from a zoo collection. After post-mortem examination, tissues were processed for histopathology, and special stains were used to demonstrate morphology of myxosporean spores. Additional kidney tissue, immersion-fixed in formalin, was processed for transmission electron microscopy. Both turtles were infected with a myxosporidian, Myxidium mackiei, in the kidney, which occluded 5 to 10% of the renal proximal convoluted tubules. The polysporic plasmodia contained pairs of developing and mature spores. Each mature, spindle-shaped spore had 2 asymmetric valves (1 overlapping, 1 overlapped), with 10 to 13 and 10 to 14 longitudinal ridges per valve, and 2 polar capsules each containing a polar filament with 4 to 5 turns. A pair of spores, each surrounded by a membrane-bound electron-lucent matrix, lay in an enclosing cell within the plasmodium. Regions of the parasite-host interface consisted of undulations of the parasite surface, with intense pinocytotic activity beneath, intermingled with the hosts' microvilli, and endocytotic channels at the apex of renal epithelial cells. The microvilli of the renal epithelial cells of infected tubules were frequently sheared or compressed, or occasionally missing; we did not detect other pathology induced by the parasite. Our report of M. mackiei in L. punctata is a new host record. Both individuals also had disseminated pale yellow nodules (bacterial granulomas) present in lung, heart, kidney, and skeletal muscle, and both were infected with coccidia (tentatively identified as Eimeria sp.) in multiple organs. The cause of death for one turtle was septicemia, but remained unknown for the other individual.

Biochemical composition of three algal species proposed as food for captive freshwater mussels

To identify potential diets for rearing captive freshwater mussels, the protein, carbohydrate (CHO), and lipid contents of two green algae, Neochloris oleoabundans, Bracteacoccus grandis, and one diatom, Phaeodactylum tricornutum, were compared at different growth stages. The fatty acid and sterol composition were also identified. Protein was greatest (55–70%) for all species at late log growth stage (LL), and declined in late stationary (LS) growth. CHO was greatest at LS stage for all species (33.9–56.4% dry wt). No significant change in lipid levels occurred with growth stage, but tended to increase in N. oleoabundans. Mean lipid content differed significantly in the order: N. oleoabundans > P. tricornutum > B. grandis. Total fatty acids (TFA) were higher at LS stage compared to other stages in the two green algae, and stationary stage in the diatom. Mean unsaturated fatty acids (UFA) as %TFA was significantly higher in N. oleoabundans than the other species. The green algae contained high percentages of C-18 polyunsaturated fatty acids (PUFAs), while the diatom was abundant in C-16 saturated and mono-unsaturated fatty acids and C-20 PUFA fatty acids. Growth stage had no effect on sterol concentration of any species. B. grandis showed significantly higher sterol levels than the other species except P. tricornutum at S stage. B. grandis was characterized by predominantly Δ5, C-29 sterols, while N. oleoabundans synthesized Δ5,7, Δ5,7,22 , and Δ7, C-28 sterols. P. tricornutum produced primarily a Δ5,22, C-28 sterol, and a small amount of a Δ7,22, C-28 sterol.

Effect of protein source and level on growth and performance of the captive freshwater prawn, Macrobrachium rosenbergii

Growth, feed conversion and survival were determined for juvenile Macrobrachium rosenbergii held in tanks under semi-controlled environmental conditions. Feeding trials incorporated water-stable diets at three levels of protein (15, 25 and 35%). The principal protein source combinations consisted either of soybean and tuna meal, or of soybean, tuna and shrimp meal. In a 244-day comparison of these diets, higher protein content produced larger prawns ( P < 0.01), but differences between sources were not significant. No significant differences existed between feed conversion ratios (range 1.36–1.72) or percentage survival (range 90.3–93.6%). Trials of several other diets were also conducted, including soybean and Tilapia meal, and copra and Tilapia meal (25% protein level) as principal protein source combinations. After 167 days on these diets, growth was inferior to that obtained with soybean and tuna meal or soybean, tuna and shrimp meal combinations. No significant differences existed between feed conversion ratios or percentages of survival. For the 244 days, a control group of prawns received no formulated diet. Growth and survival in this group during the first 110 days suggested that naturally occurring algae contributed substantially to the prawns' nutrition. Mean prawn length after 244 days on the best diet (35% protein from soybean and tuna meal) was 73 mm, and growth rate was equivalent to that achieved under pilot pond conditions.