Freshwater Groups Research Articles

A report on freshwater tailless flea, Simocephalus vetulus from Haridwar, located in foothills of Shivalik Himalaya in Uttarakhand, India

The Cladocerans, commonly known as “Water fleas” form a primitive freshwater group of micro crustacean zooplankton of the freshwater ecosystem. They play an important role in the aquatic food chain and also contribute significantly to zooplankton dynamics and secondary productivity in freshwater ecosystems. The animals used in the present study were identified as Simocephalus vetulus with the help of identification keys described by various authors in the previous studies from other parts of India. In the present study, the occurrence of “freshwater tailless flea”, S. vetulus (Crustacea- cladocera) is reported for the first time from freshwater bodies in Haridwar, located in foothills of Shivalik Himalayan region in Uttarakhand. The presence of S. vetulus “tailless water flea” will be helpful as a lab model for the health status of aquatic bodies as well as environmental monitoring.

Effects of salinity and alkalinity on fatty acids, free amino acids and related substance anabolic metabolism of Nile tilapia

A 56-day experiment was conducted to investigate the effects of ambient salinity and alkalinity on fatty acids, free amino acids and related anabolic metabolisms of Nile tilapia. The fatty acid and free amino acid contents in the muscle of tilapia cultured in saline water (SW), alkaline water (AW), saline–alkaline water (SAW) and fresh water (FW) conditions were analyzed and compared. The mRNA levels and enzymatic activities of fatty acyl desaturase (FADS2), elongation of very long-chain fatty acids (ELOVL5), Δ1-pyrroline-5-carboxylate synthase (P5CS), ornithine-δ-aminotransferase (δ-OAT), and proline dehydrogenase (PDH) were also determined. The contents of saturated and monounsaturated fatty acids were significantly higher in the AW and SAW groups than those in the SW group, and those of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) were the highest in the SAW group. The contents of flavor amino acids in the SAW and AW groups were significantly higher than that in the SW group, and that of proline in the SW, AW, and SAW groups was 3.58-, 4.11-, and 4.15-times higher than that in the FW group. The mRNA levels and enzyme activities of FADS 2, ELOVL5, PDH and P5CS were found to differ among the different groups. The results suggested that ambient salinity and alkalinity could effectively improve flesh quality of tilapia by regulating lipid and proline metabolism pathways.

Modulation of the intestinal barrier adaptive functions in red-eared slider (Trachemys scripta elegans) invading brackish waters

Globally, the increase in sea levels is leading to salinization of freshwater, which might influence the freshwater organisms such as red-eared slider, Trachemys scripta elegans. The turtle can invade brackish water environments, in which it must deal with elevated salinity in the gastrointestinal tract that could impact the intestinal function. The intestinal barrier provides a front-line of organismal defense against the chemical and biological environmental insults. In this study, the adaptive functions of the intestinal barrier including intestinal histomorphology, genes involved in intestinal barrier functions, and the intestinal micro-ecosystem were analyzed in the turtles exposed to freshwater (S0), 5‰ salinity (S5) and 15‰ salinity (S15) water for 30 days. The results showed that the intestine of T. s. elegans maintained normal histomorphological structure in the S5 group, whereas the villus height, crypt depth and the number of goblet cells in the S15 group were lower than that in the S5 and S0 groups. In addition, the relative expression levels of epithelial tight junction-related genes and intestinal immune-related genes in the gut were significantly upregulated in the S15 group, compared to the freshwater group. Mucin-2 gene expression was downregulated, but mucin-1 transcript levels were upregulated in salinity-treated groups. Furthermore, the abundances of phylum Proteobacteria, and genera Morganella and Aeromonas in the intestine were particularly enhanced in the S15 group than the S0 and S5 groups. Taken together, these results indicate that the intestinal barrier plays a protective role in T. s. elegans adaptation to brackish water environments. Our results provide a perspective on the evolution of salinity tolerance and help to evaluate the potential danger of the turtle to other species, and understand the challenges that other species must meet with rising sea levels.

Inulin alleviates hypersaline-stress induced oxidative stress and dysbiosis of gut microbiota in Nile tilapia (Oreochromis niloticus)

This study explored the alleviation of salinity-induced stress by adding dietary prebiotic inulin in Nile tilapia Oreochromis niloticus. Tilapias were administrated with four levels of inulin (0, 0.2%, 0.4% and 0.8%) at the salinity of 16 psu (practical salinity unit) for 8 weeks, and meanwhile the tilapia fed the basal diet in freshwater were served as a freshwater control. The final weight, weight gain, and specific growth rate increased but feed conversion ratio decreased in the 16 psu group compared to the freshwater group. These trends became more evident in groups of 16 psu + 0.2% inulin and 16 psu + 0.4% inulin, and the best growth was obtained in the 16 psu + 0.4% inulin group. SOD activity was significantly elevated while CAT and GST activities were markedly reduced in 16 psu group compared to the freshwater group, but these parameters returned to the freshwater group level when tilapia were fed with 0.4% inulin. Amylase and protease activities were significantly increased in 16 psu group compared to the freshwater group, but reduced and returned to the level of freshwater group by adding 0.2% and 0.4% inulin to the diet. The composition, α-diversity, and β-diversity of gut microbiota were disturbed in 16 psu group, but returned to the freshwater group pattern in 16 psu + 0.8% inulin group. The results show that dietary inulin is an effective feed additive to alleviate the oxidative stress and gut microbiota dysbiosis at 16 psu. This study suggests that dietary manipulation using inulin is a promising strategy to improve fish healthy under saline stress, and the optimal level of inulin supplementation to the diet is 0.4% for Nile tilapia at 16 psu.

Population scarcity of an estuarine crab (Chiromantes dehaani) caused by intertidal reclamation from the perspective of reduced salinity

Decreased salinity is one of the main abiotic factors causing macrobenthic degradation in reclaimed intertidal wetlands. However, our knowledge of the mechanism(s) underpinning this degradation remains surprisingly scanty. To fill this gap, here we used the crab Chiromantes dehaani as a study subject. First, we investigated differences between C. dehaani populations in fully- and semi-enclosed wetlands in 2018. Then, in controlled experiments, we exposed female C. dehaani to freshwater (salinity of 0) and two salinity levels (3 and 12) for 12, 24, and 48 days to explore the effects of reduced salinity on the osmoregulation and lipid materials of C. dehaani. Then, the surviving crabs mated with mature male crabs, and the spawning rate, fecundity, and abortion rate of female crabs quantified to reveal the effects of lower salinity on reproduction in this species. Our results revealed that no crabs could be found in the fully-enclosed zone, where the salinity level closely matched that of freshwater. In controlled experiments, the C. dehaani showed the ability of osmoregulation under freshwater condition, but it consumed more lipid materials to maintain stable osmotic pressure. Moreover, the ovary development of C. dehaani was significantly inhibited in the freshwater group, which resulted in no spawning crabs. In contrast, the breeding success of female crabs in salinities of 3 and 12 reached 90.5 ± 4.8% and 79.4 ± 6.9%, respectively. The abortion rate of embryos increased significantly after spawning crabs were exposed to the freshwater environment. Collectively, the reproduction barriers caused by salinity’s decrease may be a critical causal factor driving the scarcity of C. dehaani population in reclaimed wetlands of Yangtze estuary. These findings are expected to provide new insights into the effects of reclamation on macrobenthos.

Lipid profile and health benefit of commonly consumed fresh water and sea water fish species in the population of Serbia

Background/Aim. Dietary intake of n-3 long-chain polyunsaturated fatty acids (LC-PUFA) is important in prevention and treatment of different diseases. In general population, the average intake of n-3 LC-PUFA is often significantly lower than recommended levels. Fish lipids are rich sources of these fatty acids, of which the most important are eicosapentaenoic (20:5 n-3, EPA) and docosahexaenoic (22:6 n-3, DHA) fatty acids. This study was designed to determine and compare fat, fatty acids and lipid quality indices in 10 commercial fish species available on the Serbian market, as well as relation between their price and nutritional value. Methods. Freshwater fish originated from the Danube River in the Belgrade Region, while seawater fish were mostly from the Adriatic Sea. A gas chromatography method was used to define fatty acids in 40 fish samples after lipid extraction. Cost-minimization analysis was conducted to assess the economic utility. Results. Seawater fish had a significantly higher value of flash lipid quality compared to the freshwater fish (p < 0.05). Value of hypercholesterolaemic fatty acids (OFA) for the freshwater group was 18.70 (17.40?21.30) while the seawater group had a similar range of values 18.90 (17.55?22.75). Hypocholesterolaemic fatty acids (DFA) also showed similar ranges for both groups: 68.80 (66?70.20) for freshwater and 68.40 (64.85?73.05) for seawater group. The ratio of DHA/EPA ranged from 1.8 for sardine samples and up to 10 for tuna samples, indicating that the amount of DHA in natural samples exceeds the amount of EPA in many cases. The values of atherogenic (AI) and thrombogenic index (TI) were lower than 1 for all analysed samples. Conclusion. Sardine and mackerel had the highest content of n-3 LC-PUFA and presented the least expensive sources of EPA and DHA. The low values of AI and TI obtained from studied fish indicate its benefits from a health point of view.

Cytochrome Oxidase I (COI) gene analysis of the Nile Puffer Fish (Tetraodon lineatus) from Lake Nasser, Aswan, Egypt.

The study of the Nile Puffer Fish (Tetraodon lineatus) from Lake Nasser, Aswan, Egypt is still at a very early stage. Samples from two locations (Khor El Ramla and Tushka East) from Lake Nasser were studied. Partial sequences of the COI gene (barcode) for 20 Nile Puffer Fish from Lake Nasser were successfully amplified and analyzed. The average of nucleotides composition percent of both locations samples was 25.88, 31.54, 24.53, and 18.05 for T, C, A, and G respectively. The base composition analysis of both locations samples of the COI sequence revealed that AT content (50.41%) was higher than GC (49.59%). The current results of the phylogenetic analysis of Lake Nasser samples indicate that there are three groups of Nile Pufferfish in Lake Nasser. Two of them are presented in the south and the last one in the north and south of the Lake. Conversely, the GenBank and Lake Nasser samples indicate that there are two haplotypes from Tetraodon lineatus of the two locations from Lake Nasser based on the partial sequence of the COI gene. The first haplotype includes different samples from the two studied locations (North and south Lake) and the second includes five samples from the North Lake. Finally, the present phylogenetic results for Nile Pufferfish in Lake Nasser (Tetraodon lineatus), together with other African freshwater groups, matched with the monophyletic origin of African freshwater Puffer fishes. As a conclusion, overall data collected from this study will be fundamental for the Lake Nasser fishery and the handling of the problems caused by Nile pufferfish. Therefore, proper utilization of this species towards sustainable management, nutritional composition, and biosecurity issues will lead to achieving a sustainable blue economy.

Modelling the distribution of large branchiopods (Crustacea: Notostraca, Anostraca & Spinicaudata) for predicting occurrences in poorly sampled regions

Large branchiopods are one of the most iconic species groups in temporary pools. Due to their specific biology and massive habitat degradation, they are one of the most threatened freshwater species groups. In this study, we used a unique dataset on the distribution of large branchiopods on a national scale (Austria), data on the distribution of temporary pools, and environmental variables to model the potential distribution of seven large branchiopod species. For species distribution modeling, we used six predictors which were assumed to be potentially relevant for explaining large branchiopod distribution. We used three modeling techniques (Generalized Linear Models, General Boosted Models, Random Forests) for distribution modeling. While some predictors (e.g. mean annual temperature, mean annual precipitation and the proportion of arable land at the temporary pool) were important for all target species, the importance of the other variables (size of the temporary pool, connectivity, flooding probability) was variable among species, and partly also between the three model techniques used. The resulting ensemble distribution maps, which are based on ensemble models of the above-mentioned modeling techniques, show the distribution of occurrence probabilities for the modeled species. These maps can serve as a baseline for future surveying regions that have been under-sampled so far. Furthermore, as these maps identify regions where large branchiopods likely do occur, conservation measures can be prioritized towards these regions. Finally, we discuss conservation measures which should improve land use by farmers to appropriately protect large branchiopods and their habitats, temporary pools.

Type materials of the species of the Planorbidae (Mollusca, Gastropoda, Hygrophila) described by Shuichi Mori

ABSTRACTThe planorbid species that were described by Shuichi (Syuiti) Mori from Japan have long been enigmatic and their taxonomy has been highly confused. This situation is also an impediment to action for the conservation of Japanese planorbids which are one of the most threatened freshwater snail groups in the country. Based on our examination of Shuichi Mori’s collection stored in the Kyoto University Museum, type materials of the taxa described by him are re-illustrated and re-examined for the first time. Our examination suggested that Gyraulus amplificatus (Mori, 1938) is not a morphological form of Gyraulus biwaensis but a distinct species. Gyraulus pulcher (Mori, 1938) can be regarded as a junior synonym of Gyraulus chinensis.

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

Assessment of phytoplankton community structure and water quality in the Eastern Harbor of Alexandria, Egypt

The species composition and abundance of phytoplankton were studied weekly from 16 June 2011 to 30 May 2012 at a fixed station in the Eastern Harbor (EH), a semi-closed basin; in Alexandria City The results indicated that, the phytoplankton standing crop varied between a minimum of 1.08 × 103 and a maximum of 1.57 × 106 cells·l−1. The phytoplankton community was represented by a total of 132 species, including 72 diatoms, with a percentage frequency of 96.42% and 37 dinoflagellates (3.34%), as well as few representatives of different freshwater groups. The Shannon–Wiener diversity, varied broadly from 0.0076 to 3.19 bits. cell−1, Stable community accompanied the low values, while higher diversities corresponded to non-steady state periods. Water quality was estimated according to phytoplankton density and based on inorganic nutrient data (P-PO4, N-NO3, N-NO2, N-NH3), the aquatic system was divided into oligotrophic, mesotrophic and eutrophic water types. A correlation coefficient of biological factors with some environmental conditions are provided and discussed. Further, Principle Component Analysis (PCA) which was used to analyze water quality of weekly data and its results were discussed.

Comparison of pulmonary circulation hemodynamics and respiratory mechanics induced by drowning with equal volume of freshwater and seawater in sheep: a randomized controlled study

To compare the effects of freshwater and seawater drowning on sheep's pulmonary circulation hemodynamics and respiratory mechanics. According to the random number table method, healthy crossbred sheep were divided into freshwater drowning group (n = 12) and seawater drowning group (n = 12). 30 mL/kg of freshwater or seawater was infused respectively through trachea for approximately 5 minutes. Before the drowning, immediately after drowning, and 30, 60, 120 minutes after drowning, the systemic circulation hemodynamic parameters [heart rate (HR), mean arterial pressure (MAP), cardiac output (CO)] were monitored by pulse indicator continuous cardiac output (PiCCO); the respiratory parameters were obtained through the ventilator, including tidal volume (VT), lung compliance (Cdyn), oxygenation index (PaO2/FiO2), peak airway pressure (Ppeak)]; PiCCO and the right heart floating catheter (Swan-Ganz catheter) was used to measure pulmonary hemodynamic parameters [pulmonary systolic pressure (PAS), pulmonary diastolic pressure (PAD), pulmonary artery wedge pressure (PAWP), and extravascular lung water (EVLW)]. The animals were sacrificed at the end of the experiment, and the amount of residual water in the respiratory tract was measured; the pathological changes in the lung tissue were observed by hematoxylin-eosin (HE) staining. (1) Systemic circulation hemodynamics: compared with the values before drowning, HR, MAP, and CO at the time of immediately after drowning in both freshwater and seawater were significantly increased and peaked. In addition, all indicators in the freshwater drowning group were significantly higher than those in the seawater drowning group [HR (bpm): 170.75±1.87 vs. 168.67±2.27, MAP (mmHg, 1 mmHg = 0.133 kPa): 172.92±1.62 vs. 159.42±3.18, CO (L/min): 13.27±0.71 vs. 10.33±0.73, all P < 0.05]. (2) Respiratory parameters: compared with values before drowning, PaO2/FiO2, VT, and Cdyn decreased immediately in both freshwater and seawater drowning groups, Ppeak was significantly increased; in addition, the values in the seawater drowning group were decreased or increased more significantly than freshwater drowning group [PaO2/FiO2 (mmHg): 37.83±1.99 vs. 60.42±5.23, VT (mL): 86.25±7.66 vs. 278.75±9.67, Cdyn (mL/cmH2O): 8.86±0.33 vs. 23.02±0.69, Ppeak (cmH2O, 1 cmH2O = 0.098 kPa): 42.17±2.69 vs. 17.67±1.15, all P < 0.01]. In addition, PaO2/FiO2 in the freshwater drowning group was gradually increased over time, while the seawater group continued to decline. (3) Pulmonary circulation hemodynamic parameters: PAS, PAD, PAWP at the time of immediately after drowning in both freshwater and seawater groups were significantly higher than before drowning; in addition, the freshwater drowning group was significantly higher than the seawater drowning group [PAS (mmHg): 34.58±2.87 vs. 26.75±1.66, PAD (mmHg): 27.25±1.22 vs. 16.75±0.87, PAWP (mmHg): 27.83±1.85 vs. 11.75±1.82, all P < 0.01]. Thereafter, PAS and PAD in the freshwater drowning group gradually decreased, while the parameters in the seawater drown group continued to increase. PAWP gradually decreased after freshwater or seawater drowning, and recovered to pre-drowning levels 120 minutes after drowning and 30 minutes after drowning, respectively. EVLW continued to increase after freshwater drowning, reaching a peak at 30 minutes, and then decreased, until 120 minutes after drowning was still significantly higher than that before drowning (mL/kg: 10.73±1.27 vs. 7.67±0.69, P < 0.01); EVLW could not be measured. (4) Residual water in the respiratory tract: residual water in the freshwater drowning group was significantly less than that in the seawater drowning group (mL: 164.33±25.21 vs. 557.33±45.23, P < 0.01). (5) HE staining: partial alveolar atrophied in the freshwater drowning group, some alveolar spaces were broken, alveolar spaces and alveolar cavity showed a little powdery substance deposition; it was noted that alveolar expanded in the seawater drowning group, alveolar spaces were broken and bleeding and edema were obvious in the interstitial space. The effect of seawater drowning on the respiratory mechanics and pulmonary circulation of animals is more obvious than that of freshwater drowned animals, and the amount of residual water in the respiratory tract is also significantly more than that of freshwater drowned animals.

Benthic macroinvertebrates as bioindicators of environmental quality of Pará River estuary, a wetland of Eastern Amazon

The study characterized and evaluated the use of the benthic macroinvertebrate community as an indicator of impacts in different estuarine environments around the Industrial Port Complex (IPC) of Vila do Conde (Pará State, Amazon region). Fauna of beaches and rivers, in sectors of the estuary under different degrees of environmental impact (high, medium, and low), was compared in different seasonal periods. Macrofauna was composed of typically fresh-water and estuarine groups. Beaches presented sediment with a texture ranging from medium to coarse sand, with a less rich macrofauna ( = 4.5 ± SE 0.3 taxa/sample) and dense ( = 1,838.1 ± 164.8 ind./m2) of organisms when compared to rivers ( = 5.9 ± 0.3 taxa/sample, and 3,248.9 ± 77.0 ind./m2), which were environments more muddy. For both environments, sites in the high-impact sector were less rich ( = 4.7 ± 0.3 taxa/sample) and dense ( = 2,812.9 ± 232.7 ind./m2) when compared to those in the low-impact sector ( = 7.6 ± 0.4 taxa/sample, and 3,314.3 ± 230.1 ind./m2). Richness ( = 6.4 ± 0.3 taxa/sample) and density ( = 3,859.4 ± 190.2 ind./m2) were higher in the rainier season when compared to the less rainy season ( = 4.8 ± 0.3 taxa/sample, and 1,933.0 ± 172.1 ind./m2). However, there were no significant seasonal changes in composition. Results indicated that the structure of the benthic macroinvertebrate community surrounding the IPC responds to the loss of environmental quality, with extreme effects of a drop in abundance and diversity. Taxa that are more tolerant (Namalycastis caetensis, Cirolana sp., Pseudosphaeroma sp., Tubificidae, and Chironomidae) and sensitive (Hydropsychidae and Eteone sp.) to impact conditions were identified and evaluated as potential bioindicators.

Phylogeny of the freshwater lineages within the phyla Actinobacteria (Overview)

This review presents molecular classification of freshwater Actinobacteria based on the phylogeny of the 16S rRNA gene. We show the classification of the entire phylum Actinobacteria and the taxonomic rank of freshwater lineages of Actinobacteria within this phylum. The discovery history of different groups of freshwater Actinobacteria is considered. We have systematized the information about the phylogeny of cultivated and uncultivated freshwater Actinobacteria and give their brief description. Data is provided on freshwater groups of Actinobacteria found in different ecotopes of Lake Baikal.

Metagenomic Analysis of Virioplankton from the Pelagic Zone of Lake Baikal.

This study describes two viral communities from the world’s oldest lake, Lake Baikal. For the analysis, we chose under-ice and late spring periods of the year as the most productive for Lake Baikal. These periods show the maximum seasonal biomass of phytoplankton and bacterioplankton, which are targets for viruses, including bacteriophages. At that time, the main group of viruses were tailed bacteriophages of the order Caudovirales that belong to the families Myoviridae, Siphoviridae and Podoviridae. Annotation of functional genes revealed that during the under-ice period, the “Phages, Prophages, Transposable Elements and Plasmids” (27.4%) category represented the bulk of the virome. In the late spring period, it comprised 9.6% of the virome. We assembled contigs by two methods: Separately assembled in each virome or cross-assembled. A comparative analysis of the Baikal viromes with other aquatic environments indicated a distribution pattern by soil, marine and freshwater groups. Viromes of lakes Baikal, Michigan, Erie and Ontario form the joint World’s Largest Lakes clade.

Antonymous nature of freshwater phytoplankton in the tropical estuarine environments of Goa, southwest coast of India

Estuaries are the most dynamic marine ecosystems serving as potential spawning and nursery grounds for an array of marine fishes and their life stages. Producer community explicitly represented by phytoplankton form essential inertia to propagate the food chain, however on the contrary also could be detrimental due to blooming events. The present study envisages studying the distribution of green algae (Chlorophyceae) and blue–green algae (Cyanophyceae) in two tropical estuaries, namely Chapora and Sal in Goa along the west coast of India. Water samples were collected during July–December, 2016, comprising both monsoon and non-monsoon season. A total of twenty-five species of Chlorophyceae and three species of Cyanophyceae were recorded from these estuaries. Among the two, the Chlorophyceae group was found to be dominant and diverse. These two groups of phytoplankton were strongly influenced by the season in both the estuaries. The Multi-dimensional scaling (MDS) plots revealed salinity as one of the crucial parameters in the composition and distribution of these freshwater groups. Based on Redundancy analysis (RDA) plots, it was noted that, in addition to salinity, other physicochemical parameters (DO, pH, and nitrate concentration) could also affect the distribution of these groups. Two toxic bloom-forming genera (Microcystis and Oscillatoria) belonging to the Cyanophyceae group were reported. It is imperative that such events would play a role in the proliferation of these toxic species in the higher trophic levels.

Global parasite trafficking: Asian Gyrodactylus (Monogenea) arrived to the U.S.A. via invasive fish Misgurnus anguillicaudatus as a threat to amphibians

A monogenean flatworm Gyrodactylus jennyae Paetow, Cone, Huyse, McLaughlin & Marcogliese, 2009 was previously described as a pathogen on bullfrog Lithobates catesbeianus Shaw, 1802, in a Canadian captive population originating in Missouri, U.S.A. The ITS barcoding of G. jennyae showed relatedness to Asian Gyrodactylus macracanthus Hukuda 1940, a parasite of the Asian loach Misgurnus anguillicaudatus Cantor, 1842. The resulting suggestion that the globally invasive pet-trade of fish may be a mechanism for arrival of Gyrodactylus species to North America provided the framework for the current study. The present study was undertaken following the discovery of two other species of Gyrodactylus in a population of illegally introduced M. anguillicaudatus in New York State. Here the invasion hypothesis was tested via DNA sequencing of the ITS of the two Gyrodactylus species obtained from M. anguillicaudatus from New York, termed Gyrodactylus sp. A and Gyrodactylus sp. B. Both Gyrodactylus sp. A and Gyrodactylus sp. B were closely related to G. jennyae and G. macracanthus, and all belong to a molecularly well-supported monophyletic Asian freshwater group. In conclusion, this invasive fish has trafficked at least three parasite species to the U.S.A., one of them also found on frog. This route from the Asian wetlands to other continents is similar to that of amphibian chytrid fungi of genus Batrachochytrium Longcore, Pessier & Nichols, 1999.

Passive acoustic monitoring as a potential tool to survey animal and ecosystem processes in freshwater environments

Abstract Biodiversity in freshwater habitats is decreasing faster than in any other type of environment, mostly as a result of human activities. Monitoring these losses can help guide mitigation efforts. In most studies, sampling strategies predominantly rely on collecting animal and vegetal specimens. Although these techniques produce valuable data, they are invasive, time‐consuming and typically permit only limited spatial and temporal replication. There is need for the development of complementary methods. As observed in other ecosystems, freshwater environments host animals that emit sounds, either to communicate or as a by‐product of their activity. The main freshwater soniferous groups are amphibians, fish, and macroinvertebrates (mainly Coleoptera and Hemiptera, but also some Decapoda, Odonata, and Trichoptera). Biophysical processes such as flow or sediment transport also produce sounds, as well as human activities within aquatic ecosystems. Such animals and processes can be recorded, remotely and autonomously, and provide information on local diversity and ecosystem health. Passive acoustic monitoring (PAM) is an emerging method already deployed in terrestrial environments that uses sounds to survey environments. Key advantages of PAM are its non‐invasive nature, as well as its ability to record autonomously and over long timescales. All these research topics are the main aims of ecoacoustics, a new scientific discipline investigating the ecological role of sounds. In this paper, we review the sources of sounds present in freshwater environments. We then underline areas of research in which PAM may be helpful emphasising the role of PAM for the development of ecoacoustics. Finally, we present methods used to record and analyse sounds in those environments. Passive acoustics represents a potentially revolutionary development in freshwater ecology, enabling continuous monitoring of dynamic bio‐physical processes to inform conservation practitioners and managers.

How leachates from wasted cigarette butts influence aquatic life? A case study on freshwater mussel Anodontites trapesiali

There are several reports on the damage smoking causes to human health available in the literature, but little is known about the environmental and biological consequences from inappropriate cigarette butt (CB) disposal in urban and natural environments. The immunotoxic, morphotoxic and mutagenic potential of leachates from cigarette butts (LCB) diluted at environmentally relevant rates (LCB1x: 1.375%; LCB10x: 13.75%) was evaluated in adult representatives of the bivalve species Anodontites trapesialis, which was adopted as model organism. Type II hyalinocytes and granulocytes (phagocytic cells) frequency increased in the hemolymph of subjects exposed to the pollutant for 14 days. Based on this outcome, LCB chemical constituents did not induce immunotoxic effects. The treatments also did not seem to have any impact on the subjects' hemocitary morphometry parameters: diameter, area, perimeter, circularity and nucleus - cytoplasm ratio. However, subjects in groups LCB1x and LCB10x recorded a larger number of hyalinocytes with some nuclear abnormality such as micronucleus, blebbed nucleus, asymmetric constriction nucleus, and nuclear multilobulation and binucleation. The association between these abnormalities and the treatments was confirmed by the Cr, Ni, Pb, Zn, Mn and Na bioaccumulation in tissue samples of the bivalve models exposed to LCB. To the best of our knowledge, this is the first report on LCB mutagenicity in representatives of a freshwater bivalve group. Given the chemical complexity of the addressed pollutants, it is imperative to develop further investigations about the topic.

Understanding environmental change through the lens of trait-based, functional, and phylogenetic biodiversity in freshwater ecosystems

In the era of the Anthropocene, environmental change is accelerating biodiversity loss across ecosystems on Earth, among which freshwaters are likely the most threatened. Different biodiversity facets in the freshwater realm suffer from various environmental changes that jeopardize the ecosystem functions and services important for humankind. In this work we examine how environmental changes (e.g., climate change, eutrophication, or invasive species) affect trait-based, functional, and phylogenetic diversity of biological communities. We first developed a simple conceptual model of the possible relationships between environmental change and these three diversity facets in freshwaters and, secondly, systematically reviewed articles where these relationships had been investigated in different freshwater ecosystems. Finally, we highlighted research gaps from the perspectives of organisms, ecosystems, stressors, and geographical locations. Our conceptual model suggested that both natural factors and global change operating at various spatial scales influence freshwater community structure and ecosystem functioning. The relationships between biodiversity and environmental change depend on geographical region, organism group, spatial scale, and environmental change gradient length. The systematic review revealed that environmental change impacts biodiversity patterns in freshwaters, but there is no single type of biodiversity response to the observed global changes. Natural stressors had different, even contradictory, effects (i.e., multiple, negative, and positive) on biodiversity compared with anthropogenic stressors. Anthropogenic stressors more often decreased biodiversity, although eutrophication and climate change affected freshwater ecosystems in a complex, more multi-dimensional way. The research gaps we identified were related, for example, to the low number of community-based biodiversity studies, the lack of information on true phylogenies for all freshwater organism groups, the missing evaluations whether species traits are phylogenetically conserved, and the geographical biases in research (i.e., absence of studies from Africa, Southern Asia, and Russia). We hope that our review will stimulate more research on the less well-known facets and topics of biodiversity loss in highly vulnerable freshwater ecosystems.