Laboratory Aquaria Research Articles

ВПЛИВ МІКОТОКСИНУ Т-2 НА ІХТІОЛОГІЧНІ ПОКАЗНИКИ КОРОПОВИХ РИБ

Mycotoxins are particularly dangerous for both animals and humans. Their toxic effects manifest even in ultra-minimal doses, which are often impossible to detect even with modern methods. The response mechanism of hydrobionts to toxic pollution in the aquatic environment is revealed through biochemical and physiological reactions aimed at restoring damaged functions. Increased human impact on aquatic ecosystems has exacerbated the survival challenges for aquatic organisms under stressful conditions. A study was conducted to investigate the impact of mycotoxin T-2 on ichthyological indicators in carp fish. Even ultra-low doses of mycotoxins can have toxic effects, and their presence is often difficult to detect with modern methods. Changes in morphometric indicators and metabolic processes are integral components of complex nonspecific reactions that occur in response to any stress factors. During long-term exposure or at high intensity, serious and irreversible damage can occur, potentially leading to various pathologies or even death of the organism. Based on this, the aim of the study was to examine the effect of mycotoxin T-2 on the ichthyological indicators of carp fish. A laboratory experiment showed that exposure to mycotoxin T-2 led to a slight increase in the fatness ratio of fish, which could be explained by tissue swelling. A similar trend was observed regarding the liver index in carp. In the case of crucians, the liver index remained unchanged. Additionally, no significant changes were found in the indicators of body height, head height, and compactness. This can be attributed to the relatively short two-week experimental period, which may not be sufficient to detect differences in morphological parameters. During the experiment, when mycotoxin T-2 was introduced into laboratory aquariums, changes were detected in the protein metabolism components in the blood of fish. Total protein levels decreased by 29% in carp and 32% in crucian carp exposed to mycotoxin T-2. The study of ALT and AST activity in the blood under the influence of mycotoxin revealed an increase in the activity of aminotransferases in both carp and crucian carp. From the blood, free amino acids are transferred to the liver, where in response to ALT and AST, their transamination increases, explaining the heightened activity of these enzymes.

Amphibious ethics and speculative immersions: laboratory aquariums as a site for developing a more inclusive animal geography

ABSTRACT Human capacity to sense and respond to the suffering of non-human animals is key to animal care and welfare. Intuitively these modes of relating seem best suited to interactions between humans and warm-blooded mammals who share human-like facial features and characteristics. Animal geographers and those working in animal welfare have noted the challenges that humans face in learning to care about fishes, and how this leads to welfare guidelines and regulations which are poorly suited to aquatic species. This paper draws on interviews with laboratory aquarists and biomedical researchers to explore how they have learnt to sense and respond to the needs of fishes in the laboratory. We offer two key observations. Firstly, despite significant bodily differences, humans find ways to empathise with fishes. Secondly, whilst observations of bodies and behaviours predominate in laboratory mammal welfare assessments, when working with fishes water quality serves as an important proxy for species health. We conclude that the laboratory aquarium signifies methodological and conceptual limits in contemporary animal geographies. We further argue that these barriers should be understood as cultural, and – as we demonstrate – that there is consequently scope and capacity to reach beyond them by engaging in amphibious ethics and speculative immersions.

Study on the Genotoxic Effect of Copper Sulphate in the Spotted Snakehead Fish Channa Punctatus (Bloch, 1793)

The genotoxic effects of a herbicide containing CuSO4 were assessed using the micronucleus assay in Channa punctatus. The study involved intraperitoneal administration of three different doses (1.0, 3.0, and 5.0 mg/kg body weight) and exposure to varying concentrations of copper sulphate (15, 25, and 35 ppm) in laboratory aquaria. Peripheral blood smears stained with 15 to 20% Giemsa (pH=7.0) were examined. Apart from micronuclei, the herbicide induced other nuclear and cytoplasmic abnormalities. The findings suggest a direct impact of increasing CuSO4 concentration on the biological samples of Channa punctatus. This fish species is commonly found in freshwater habitats like ponds, ditches, wetlands, and rice fields, especially in Odisha, India. India is crucial for maintaining aquatic biodiversity. The study highlights the potential detrimental effects of improper use of CuSO4 containing pesticides in agriculture on Channa punctatus and emphasizes the need for careful management of such chemicals to protect aquatic ecosystems.

Salinity tolerance of Nile tilapia (Oreochromis niloticus) to seawater and growth responses to different feeds and culture systems

The inability to acclimatise, feed and grow Nile tilapia (Oreochromis niloticus) in full seawater salinity has been a major obstacle to farming in marine waters. We investigated the salinity tolerance of O. niloticus and growth responses to different feeds and culture systems. Fish were first acclimatised to different salinities in laboratory aquaria, and the survival and growth performance in sea water were then assessed in aquaria, cages and ponds. Acclimatization to seawater salinity (5 – 30) took place at a rate of 5 every 9 days. Fish were stocked at densities of 5 fish/20 L in aquaria, 5 fish/m2 in cages and 3 fish/m2 in ponds. Replicates of 5, 3 and 3 were performed in aquaria, cages and ponds, respectively. Fish were fed on commercial (1 and 2) and locally formulated (30 % crude protein) diets. Mortality rates were higher in aquaria, when fish were introduced to salinities between 5 and 30 over 24 hours. Gradual salinity adjustments attained a stable survival rate of 78 % at salinities above 30. Aquarium experiments indicated significant negative correlation between salinity and survival (p < 0.001, r = 0.387) and daily growth rates varied with diet (0.01 – 0.05 g/day). Acclimatized fish showed minimal mortality in ponds and cages. Daily growth rates varied with diet and culture system; 0.54 - 2.48 g/day in cages and 1.1 - 2.5 g/day in ponds. Fish fed on commercial feed 2 showed significant growth rates for all culture methods (p < 0.05). O. niloticus could be fully acclimatised to seawater and attained promising growth rates when subjected to different commercial diets indicating potential of farming the species in marine waters.

Characterization and Pathogenicity of Flavobacterium psychrophilum Isolated from Rainbow Trout (Oncorhynchus mykiss) in Korea.

Flavobacterium psychrophilum is the causative agent of bacterial cold-water disease in salmonids and rainbow trout fry syndrome. This pathogen has attained a global presence and can spread both horizontally and vertically. However, it was not documented in Korea before September 2018. In this study, the objectives were to characterize Flavobacterium psychrophilum strain FPRT1, isolated from diseased rainbow trout genotypically and phenotypically. We also conducted various investigations to better understand its impact and assess potential control measures. We acquired fifty rainbow trout (approximately 70 g in weight) and transferred them to a laboratory aquarium. During the initial acclimation period, we observed mortality and examined affected fish for clinical signs. We isolated the bacterium from the spleen of infected rainbow trout using tryptone yeast extract salts agar supplemented with glucose, naming this FPRT1. Antibiotic susceptibility testing was carried out, and from the result, we selected enrofloxacin to administer to the trout orally to reduce mortality. To evaluate pathogenicity, we exposed the trout to FPRT1 at different water temperatures (8, 15, and 22 °C). Genomic analysis was conducted to identify the serotype and relatedness of FPRT1 to European strains. Affected fish displayed clinical signs, such as ulcerative lesions in the mandible, anemia with pale gills, exophthalmia, and increased mucus secretion. Internal symptoms included pale liver and enlarged spleen. FPRT1 was susceptible to erythromycin, enrofloxacin, florfenicol, oxytetracycline, and gentamicin, but resistant to oxolinic acid and sulfamethoxazole/trimethoprim. Oral administration of enrofloxacin resulted in a decrease in mortality from 28% to 6%. Pathogenicity tests revealed varying mortality rates due to FPRT1 at different temperatures. The highest rates were observed at 8 °C (ranging from 43% to 100%) for both intraperitoneal and intramuscular injections, and lower rates occurred at 22 °C (ranging from 0% to 30%), with intramuscular injections displaying higher susceptibility. Genomic analysis identified FPRT1 as serotype 2 and indicated its close genetic relationship with European strains based on the core genome and dispensable genome. The substantial genomic similarity between our strain and European strains suggests the possibility of bacterial spread through the importation of fertilized eggs from Europe. In conclusion, this study highlights the introduction of the previously undocumented pathogen (F. psychrophilum) into Korean rainbow trout populations. The detection of this pathogen and its pathogenicity assessment is not only important for understanding its impact on local aquaculture but also for establishing surveillance and control measures to prevent further transmission and outbreaks in the region.

Biochemical effects of polypropylene microplastics on red tilapia (Oreochromis niloticus) after individual and combined exposure with boron

Toxicity of single pollutants or microplastics (MPs) on organisms have been widely reported. However, their combined toxicity with boron has not been investigated. This study examined effects of individual polypropylene microplastics (PP-MPs) or mixed PP-MPs and boron on biochemical biomarkers in red tilapia (Oreochromis niloticus). O. niloticus were exposed for 21 days to pristine PP-MPs concentrations (10 or 100 mg/L), concentrations of boron alone (30 or 70 mg/L), and identical concentrations of boron in the presence of PP-MPs in laboratory aquaria. Results showed that higher concentrations of individual PP-MPs lead to significantly decreased acetylcholinesterase (AChE) in the brain and malondialdehyde (MDA) in fish liver. In contrast, superoxide dismutase (SOD), glutathione peroxidase (GPx), and glutathione (GSH) were significantly increased in fish liver exposed to higher concentrations of individual PP-MPs. Mixed concentrations of boron and PP-MPs significantly decreased AChE, GSH, and MDA activity in fish. In contrast, mixed concentrations of boron and PP-MPs significantly increased CAT, SOD, and GPx activity in fish. Findings highlight that PP-MPs may increase adverse effects of boron in O. niloticus. We present evidence that individual MPs in long-term exposure have a significant impact on biomarker responses in O. niloticus.

Simulated effects of tidal inundation and light reduction on Zostera muelleri flowering in seagrass nurseries

Zostera muelleri is an abundant seagrass species distributed through intertidal and shallow subtidal waters on the subtropical coasts of Australia. The vertical distribution of Zostera is likely defined by tidal influences, particularly desiccation and light reduction stresses. These stresses were expected to affect the flowering of Z. muelleri; however, it is difficult to quantify the effects of tidal inundation with field studies due to multiple confounding environmental factors affecting flowering (e.g., water temperature, herbivory, nutrients). A laboratory aquarium experiment compared the effects of two levels of tidal height (intertidal and subtidal) and light intensity (shaded and unshaded) on flowering timing, abundance, the ratio between flowering shoots and vegetative shoots, the morphology and duration of flower development. The earliest and greatest flowering intensity was recorded in the subtidal-unshaded group, with no flowers observed in the intertidal-shaded group. Notably, the peak flowering time was the same across shaded and unshaded treatments. Shading prolonged the timing of the first flowering and reduced the density of flowering shoots and spathes, while tidal inundation had a more significant effect on the density of flowering shoots and the density of spathes. Results showed that Z. muelleri could flower under low light conditions or tidal stress but not when exposed to both stresses simultaneously in a laboratory ‘nursery setting’. Therefore, applying subtidal-unshaded conditions appears to be beneficial for seagrass nurseries aimed at improved flower abundance despite the plants previously being collected from and adapted to intertidal meadows. Further studies that explore the suitable conditions for triggering and optimising the flowering will be beneficial in designing cost-effective seagrass nurseries.

A Study on Genotoxic Potential of Acephate in Clarias batrachus

Acephate is an insecticide made up of organophosphates. It is applied to food crops, citrus trees, on golf courses, in commercial or institutional buildings, and as a seed treatment. Products containing acephate can be purchased as tablets, liquids, granules, powders, and water-soluble packs. Acephate 75% brand name-Asataf insecticide manufactured by TATA RALLIS was used for the test. The solvent used was glass double distilled (g.d.d.) water. Fresh water catfish Clarias batrachus were collected from local water bodies of Cuttack district. All the fishes were acclimatized for fifteen days in laboratory aquaria containing 30L dechlorinated tap water prior to the initiation of the experiment. The peripheral blood smear slides were prepared from the blood collected by caudal incision in accordance with Al-Sabti (1986) and Das and Nanda (1986) with some modifications which were prepared animals were sacrificed after 24, 48 and 72 hours of Exposure and were used for each treatment group in both types of administrations (IP and dermal). The increased concentration of acephate directly affects our biological fish sample i.e. Clarias batrachus. Acephate is causing serious problems in fish as per our genotoxicity study of acephate on Clarias batrachus. Clarias batrachus is a commonly found fish species in fresh water habitat which includes ponds, ditches, wetlands and rice fields of India specially in Odisha.The irrational use of pesticides containing acephate in agriculture cause harmful effects on Clarias batrachus, which is a most important species of fish for maintaining the aquatic diversity.

Identification of a Novel Species, Cladonema digitatum sp. nov. (Cnidaria: Hydrozoa: Cladonematidae), Using DNA Barcoding and Life Cycle Analyses

In this study, a new Cladonema species was identified in a laboratory aquarium in Fuzhou, China, and named Cladonema digitatum sp. nov. based on its morphological characteristics and DNA barcoding. It is distinct from other Cladonema medusae in having a manubrium with finger-like protuberances, radial canals with Y-shaped bifurcations, tentacles with 3–11 adhesive branches, and 3–7 stinging branches growing from the main branch as side branches. The validity of C. digitatum sp. nov. was supported by molecular phylogenetic analyses based on both mitochondrial cytochrome oxidase and mitochondrial 16S rRNA sequences. Similar to other Cladonema medusae, the adhesive and stinging branches of each tentacle, oral tentacle, manubrium, and gonads in C. digitatum displayed considerable phenotypic plasticity, thus making species identification based solely on morphology difficult. Although diagnostic characters such as filiform tentacles and medusa buds of hydroids and nematocysts are also useful for species identification in the genus Cladonema, related information is missing in some Cladonema species. Thus, information on the life cycle and DNA barcoding should be updated to describe new or cryptic species and to improve the taxonomy of the genus Cladonema.

Swimming behavior and hydrodynamics of the Chinese cavefish Sinocyclocheilus rhinocerous and a possible role of its head horn structure.

The blind troglobite cavefish Sinocyclocheilus rhinocerous lives in oligotrophic, phreatic subterranean waters and possesses a unique cranial morphology including a pronounced supra-occipital horn. We used a combined approach of laboratory observations and Computational Fluid Dynamics modeling to characterize the swimming behavior and other hydrodynamic aspects, i.e., drag coefficients and lateral line sensing distance of S. rhinocerous. Motion capture and tracking based on an Artificial Neural Network, complemented by a Particle Image Velocimetry system to map out water velocity fields, were utilized to analyze the motion of a live specimen in a laboratory aquarium. Computational Fluid Dynamics simulations on flow fields and pressure fields, based on digital models of S. rhinocerous, were also performed. These simulations were compared to analogous simulations employing models of the sympatric, large-eyed troglophile cavefish S. angustiporus. Features of the cavefish swimming behavior deduced from the both live-specimen experiments and simulations included average swimming velocities and three dimensional trajectories, estimates for drag coefficients and potential lateral line sensing distances, and mapping of the flow field around the fish. As expected, typical S. rhinocerous swimming speeds were relatively slow. The lateral line sensing distance was approximately 0.25 body lengths, which may explain the observation that specimen introduced to a new environment tend to swim parallel and near to the walls. Three-dimensional simulations demonstrate that just upstream from the region under the supra-occipital horn the equipotential of the water pressure and velocity fields are nearly vertical. Results support the hypothesis that the conspicuous cranial horn of S. rhinocerous may lead to greater stimulus of the lateral line compared to fish that do not possess such morphology.

Гибридная технология очистки сточных вод красильно-отделочных производств

Introduction. Nowadays people tend to follow fashion trends and wear clothes made of brightly coloured fabrics and furs. Their production requires a large set of chemical reagents, including dyes, tanning agents, surfactants, etc. Multicomponent wastewater with changeable composition is generated following the completion of the dyeing cycle and the treatment of materials. Their further processing requires advanced innovative approaches, most of which are integrative. Wastewater treatment technologies, used by dyeing and finishing facilities, are analyzed in the article. The authors present the results of the laboratory research into the development of an integrative technology for dye extraction from wastewater using a composite sorbent obtained by pelletizing dust wastes of the metallurgical industry and supplementary phytoextraction of dyes in bio-ponds. Materials and methods. The research was conducted in the laboratory environment. The technology entails the use of a composite porous material, made of man-made raw materials used in the production of silicon and aluminum. A pelleti­zing technique, proposed by the authors, is employed to make this composite material. The sorbent production technique, its characteristics and evaluation of sorption properties are presented. The phyto-sorption properties of aquatic plants were tested in the laboratory environment. Aquatic plants, growing in the Angara river, were used in the research. Plants were collected by trawl, freed from soil, washed, and grown in the laboratory aquariums filled with dechlorinated water in conditions of moderate lighting and at the temperature of 14–16 °С. They are Elodea canadensis, Myriophyllum spicatum, and Ceratophyllum demersum. The model wastewater was represented by dye solutions, such as C.I. Acid Yellow 11, C.I. Acid Blue 120, C.I. Acid Red 1, C.I. Basic Orange 21. Results. The newly developed technology of making a composite sorbent from waste is described; its treatment efficiency is analyzed. Experimental values of the phytoremediation potential of aquatic plants are obtained. A hybrid technology for local wastewater treatment, including sorption and phyto-treatment, involving gabions and biological ponds, is proposed. Wastewater is treated in gabions filled with composite sorbent and then poured into bio-ponds with aquatic plants. Conclusions. The findings enable researchers to outline areas of further research on optimization of integrated facilities, designated for the local treatment of wastewater, generated by dyeing and finishing facilities.

Heterosis counteracts hybrid breakdown to forestall speciation by parallel natural selection.

In contrast to ecological speciation, where reproductive isolation evolves as a consequence of divergent natural selection, speciation by parallel natural selection has been less thoroughly studied. To test whether parallel evolution drives speciation, we leveraged the repeated evolution of benthic and limnetic ecotypes of threespine stickleback fish and estimated fitness for pure crosses and within-ecotype hybrids in semi-natural ponds and in laboratory aquaria. In ponds, we detected hybrid breakdown in both ecotypes but this was counterbalanced by heterosis and the strength of post-zygotic isolation was nil. In aquaria, we detected heterosis in limnetic crosses and breakdown in benthic crosses, which is suggestive of process- and ecotype-specific environment-dependence. In ponds, heterosis and breakdown were three times greater in limnetic crosses than in benthic crosses, contrasting the prediction that the fitness consequences of hybridization should be greater in crosses among more derived ecotypes. Consistent with a primary role for stochastic processes, patterns differed among crosses between populations from different lakes. Yet, the observation of qualitatively similar patterns of heterosis and hybrid breakdown for both ecotypes when averaging the lake pairs indicates that the outcome of hybridization is repeatable in a general sense.

Different responses to artificial ventilation in two stratified coastal basins

We studied the effects of pumping surface water down through the pycnocline (i.e. artificial ventilation) on hydrodynamics, oxygen concentrations, hydrogen sulfide, and nutrients in two anoxic coastal basins (Lännerstasundet and Sandöfjärden). In addition, in a corresponding laboratory aquarium experiment, pumping of less saline surface water entrained dense bottom water with a mixing ratio of 6.8 and illustrated dispersal below the pycnocline. Oxygen saturation increased from 0 to 20%; oxygen penetrated poorly into the sediment of the aquarium. In the salinity-stratified Lännerstasundet basin, ventilation also oxidized the anoxic bottom water. The ventilation removed hydrogen sulfide and decreased the sub-pycnocline water pools of phosphorus and ammonium, which was not observed in a neighboring reference basin. The summertime ventilation warmed and made the sub-pycnocline water less saline. In the autumn, the inflows of cooled water from the surroundings with equal or higher salinity promoted its sinking in the relatively warm ventilated basin. The inflows maintained oxygen concentrations between 4 and 8 mg L−1 for months after the ventilation ended. In contrast to Lännerstasundet, ventilation did not prevent formation of anoxia and release of nutrients in the temperature-stratified Sandöfjärden. Here, the ventilation capacity was less than that in Lännerstasundet and ventilation expanded the sub-thermocline bottom area, warmed the bottom sediments, and probably displaced oxic water from the experimental area. The ventilation did not promote density conditions for inflows and no marked inflow-induced oxidation was observed after midsummer. We conclude that a significant amount of anoxic water was entrained into the ascending plume which reduced the oxygen content below the pycnocline ventilation in aquarium experiment. Additionally, summertime ventilation may improve the status of the salinity-stratified basins for further oxidation. The improvement occurs due to autumn cooling and favorable basin topography, which promote inflows of oxic water with larger density and thereby, renewal of bottom water in the pumped basin. The semi-enclosed and temperature-stratified basin cannot form such favorable density conditions for inflows and thus ventilation is less efficient.

Impact of seawater temperature on the Pacific oyster (

Context Intertidal estuarine environments expose oysters to wide temperature variations. This can shift their microbiome composition towards pathogen-dominated communities. Understanding the impact of temperature on the microbiome will facilitate oyster health management. Aims The present study was conducted to (1) assess the Pacific oyster microbiome at different temperatures (21°C, 22°C, 26°C and diurnal fluctuation between 22°C and 26°C) and (2) investigate microbiome changes in response to exposure to the pathogen Ostreid herpesvirus-1 (OsHV-1) at different temperatures. Methods Pacific oysters (15 months of age; n = 480) were acclimated to different temperatures in laboratory aquaria. Samples were obtained before and after acclimation and after OsHV-1 exposure for quantification of OsHV-1, total bacteria and Vibrio, by quantitative PCR. Bacterial 16S rRNA gene (V1–V3) sequences were used to characterise the gill bacterial community. Key results The alpha diversity (number of observed amplicon sequence variants) and total number of bacteria associated with the gills of oysters did not change with acclimation to different water temperature profiles, but there was variation in beta diversity. The highest mortality after OsHV-1 exposure occurred at 26°C and these, together with oysters at 22/26°C, had a higher concentration of OsHV-1 DNA compared with to the ones at the lower constant temperatures (P < 0.05). The total bacterial quantity increased after the OsHV-1 challenge in oysters at 22/26°C. The alpha diversity of microbiota increased after the OsHV-1 challenge in oysters at 21°C and 22/26°C. The beta diversity changed both after acclimation and OsHV-1 challenge. The highest abundance of Vibrio and higher OsHV-1 loads were seen in OsHV-1-challenged oysters at 26°C (P < 0.05). Conclusions The gill microbiome altered with seawater temperature and OsHV-1 challenge. Higher mortality following OsHV-1 exposure was associated with a higher water temperature and greater abundance of Vibrio spp. arising from the microbiome. Implications Higher seawater temperature can be considered a key risk factor influencing oyster health by altering the microbiome, increasing susceptibility to OsHV-1 and increasing the Vibrio fraction in the oyster microbiome.

Effect of different fish feeds on water quality and growth of crucian carp (Carassius carassius) in the presence and absence of prometryn

Few data are available regarding comprehensive or quantitative assessment of fish feed considering both the environmental and feeding impacts. Aiming to fill the gap, an experimental study to investigate the effects of three fish feeds on concentrations of nutrients and crucian carp (Carassius carassius) growth was conducted in laboratory aquariums in the presence and absence of prometryn. Results showed that weight gain rates of crucian carp treated with Tong Wei (TW) feed were 106.3% and 2.0% higher than that of Zhong Shan (ZS) and Zhong Liang (ZL) feeds, a possible explanation was that the quality of protein in TW feed was highest as evidenced by the protein efficiency ratios. Meanwhile, TW feed posed relatively lighter effects on water qualities (between ZL and ZS). Prometryn significantly inhibited the growth of crucian carp and thus affected concentrations of nutrients in water indirectly. The relationships between weight gain rates of fish and concentrations of nutrients in water (R2 = 0.929–0.990) were developed. In sum, this study suggested that it is realizable to obtain better fish growth performance with lesser degrading effects on water qualities by producing and selecting appropriate feed regardless of prometryn existence, and the developed equations could be used as a basis for future studies.

Measuring Stony Coral Tissue Loss Disease Induction and Lesion Progression Within Two Intermediately Susceptible Species, Montastraea cavernosa and Orbicella faveolata

During the last several decades, Florida’s Coral Reef (FCR) has been impacted by both global and local stressors that have devastated much of its living coral cover. Additionally, since 2014 FCR has experienced a lethal disease outbreak termed stony coral tissue loss disease (SCTLD). Here, we examined SCTLD spreading dynamics within and among fragmented coral colonies and quantified lesion progression rate of two intermediately susceptible species—Montastraea cavernosaandOrbicella faveolata—through induction experiments conducted in laboratory aquaria.M. cavernosacolonies showing subacute tissue loss were sequentially fragmented parallel to the lesion edge to determine whether isolated tissue that showed no tissue-loss signs, referred to as isolated apparently healthy (AH) donor fragments, would subsequently exhibit tissue loss. Additionally, AHM. cavernosaandO. faveolatafragments, referred to as recipient fragments, were placed in direct contact with theM. cavernosadonor fragments to assess incidence of new tissue-loss lesions. Finally, AHM. cavernosadonor fragments were placed in direct contact with recipientM. cavernosaandO. faveolatafragments to account for aggression from direct contact. Samples were collected for histopathology of the corals through time. Many isolated AH donor fragments developed tissue-loss lesions during the 60-day study, suggesting SCTLD may be systemic within small-sized colonies. Our results confirmed that physical contact between recipient fragments and subacute SCTLD-lesioned tissue often led to tissue loss in recipient fragments. None of the control recipient or donor fragments experienced tissue loss. Grossly, multifocal lesions started on or adjacent to the septal and costal basal body walls with tissue loss progressing across the polyp septa and coenenchyme, respectively, in both species. Histologically, initial tissue-loss lesions in both species exhibited characteristic lytic necrosis (LN) at the basal body wall of the gastrodermis.O. faveolataexhibited higher rates of lesion appearance and subsequent mortality compared toM. cavernosa, but once a lesion appeared,M. cavernosalost tissue faster thanO. faveolata.This work contributes to the growing knowledge of SCTLD dynamics and highlights the differences in lesion progression within susceptible species.

The Starfish Asterina pectinifera: Collection and Maintenance of Adults and Rearing and Metamorphosis of Larvae.

Here we describe methods for (a) collecting starfish during their breeding period; (b) maintaining adults with fully grown gonads in laboratory aquaria; (c) rearing fertilized eggs to brachiolaria larvae, and (d) inducing larvae to metamorphose into juveniles under laboratory conditions. Such protocols should facilitate various analyses of starfish development throughout the entire life cycle of these model organisms.

Natural breeding of freshwater apple snail Pila globosa (Swainson) in pond and aquarium

The freshwater apple snail, Pila globosa is one of the most abundant and commercially valued molluscs. Over exploitation of P. globosa for prawn farming is an alarming condition. The present study is aimed at elucidating the breeding behavior and reproduction process of P. globosa. The natural breeding experiment was conducted in two ponds- a 52 decimal pond in Gopalgonj sadar and a 40 decimal pond in Kotalipara. The ponds were prepared by applying lime at the rate of 3 kg/decimal and then filled up with water up to 30cm. Wild snails were stocked at the rate of 600 no./decimal. Organic compost (cow-dung, mustard oilcake and urea at the ratio of 1:1:0.5at the rate of 2.5 kg/decimal respectively) spread throughout the pond. Several male and female specimens were collected from experimental gher and brought to the laboratory aquarium to observe their breeding behavior. At the bottom of aquarium substrate like plastic bottle, marbel, artificial tree etc. were provided for egg laying. Breeding involves three processes: copulation, fertilization and laying. Copulation occurs in water on moist land and it takes about 3-4 hrs, then both separated. Fertilization is internal in P. globosa. Egg laying started 2 or 3 days after copulation. They lay eggs in sheltered places or moist land near water in the dyke. A single female lays eggs average 387.89±167.65 no. per clot at a time. The time elapsed between the first and the last hatchings ranged from 6 to 25 days and for 80% of the 5 egg masses were studied. Considering all the eggs in the egg masses (n=1856) more than 60% of the eggs hatched within 13 days of the first hatching. It needs about 25 days for full clot to be hatched. In the laboratory condition hatching success was observed about 80%.

Microbiota characterization of Exaiptasia diaphana from the Great Barrier Reef

BackgroundCoral reefs have sustained damage of increasing scale and frequency due to climate change, thereby intensifying the need to elucidate corals’ biological characteristics, including their thermal tolerance and microbial symbioses. The sea anemone, Exaiptasia diaphana, has proven an ideal coral model for many studies due to its close phylogenetic relationship and shared traits, such as symbiosis with algae of the family Symbiodiniaceae. However, established E. diaphana clonal lines are not available in Australia thus limiting the ability of Australian scientists to conduct research with this model. To help address this, the bacterial and Symbiodiniaceae associates of four Great Barrier Reef (GBR)-sourced E. diaphana genotypes established in laboratory aquaria and designated AIMS1–4, and from proxies of wild GBR E. diaphana were identified by metabarcoding of the bacterial 16S rRNA gene and eukaryotic rRNA gene ITS2 region. The relationship between AIMS1–4 and their bacterial associates was investigated, as was bacterial community phenotypic potential. Existing data from two existing anemone clonal lines, CC7 and H2, were included for comparison.ResultsOverall, 2238 bacterial amplicon sequence variants (ASVs) were observed in the AIMS1–4 bacterial communities, which were dominated by Proteobacteria and Bacteroidetes, together comprising > 90% relative abundance. Although many low abundance bacterial taxa varied between the anemone genotypes, the AIMS1–4 communities did not differ significantly. A significant tank effect was identified, indicating an environmental effect on the microbial communities. Bacterial community richness was lower in all lab-maintained E. diaphana compared to the wild proxies, suggesting a reduction in bacterial diversity and community phenotypic potential due to culturing. Seventeen ASVs were common to every GBR lab-cultured anemone, however five were associated with the Artemia feedstock, making their specific association to E. diaphana uncertain. The dominant Symbiodiniaceae symbiont in all GBR anemones was Breviolum minutum.ConclusionDespite differences in the presence and abundance of low abundance taxa, the bacterial communities of GBR-sourced lab-cultured E. diaphana are generally uniform and comparable to communities reported for other lab-cultured E. diaphana. The data presented here add to the global E. diaphana knowledge base and make an important contribution to the establishment of a GBR-sourced coral model organism.

The role of freshwater bioacoustics in ecological research

AbstractConventional methodologies used to estimate biodiversity in freshwater ecosystems can be nonselective and invasive, sometimes leading to capture and potential injury of vulnerable species. Therefore, interest in noninvasive surveying techniques is growing among freshwater ecologists. Passive acoustic monitoring, the noninvasive recording of environmental sounds, has been shown to effectively survey biota in terrestrial and marine ecosystems. However, knowledge of the sounds produced by freshwater species is relatively scarce. Furthermore, little is known about the representation of different freshwater taxonomic groups and habitat types within the literature. Here we present results of a systematic review of research literature on freshwater bioacoustics and identify promising areas of future research. The review showed that fish are the focal taxonomic group in 44% of published studies and were studied primarily in laboratory aquaria and lotic habitats. By contrast, lentic habitats and other taxonomic groups have received relatively little research interest. It is particularly striking that arthropods are only represented by 26% of studies, despite their significant contributions to freshwater soundscapes. This indicates a mismatch between the representation of taxonomic groups within the freshwater bioacoustic literature and their relative acoustic contribution to natural freshwater soundscapes. In addition, the review indicates an ongoing shift from behavioral studies, often with focus on a single taxonomic group, towards field‐based studies using ecoacoustic approaches. On the basis of this review we suggest that future freshwater bioacoustics research should focus on passive acoustic monitoring and arthropod sound, which would likely yield novel insights into freshwater ecosystem function and condition.This article is categorized under: Water and Life > Nature of Freshwater Ecosystems Water and Life > Conservation, Management, and Awareness Water and Life > Methods