PeerJ Preprints: Freshwater Biologyhttps://peerj.com/preprints/index.atom?journal=peerj&subject=1412Freshwater Biology articles published in PeerJ PreprintsPhysical habitat modeling methodology and applicationshttps://peerj.com/preprints/280052019-10-032019-10-03Ravi Nalamothu
The water management districts in Florida are required by s. 373.042, F.S. to establish minimum flow and levels (MFLs) for a priority list of water bodies that is updated each year. These MFLs are established for water bodies to prevent “significant harm” to the water resources or ecology because of withdrawals for beneficial use, and can be an effective water resource management tool. Protection of the resource from significant harm is a benefit to the variety of existing users of the resource as well as the ecological systems supported by the water bodies. This article presents an overview of a modeling technique and an associated tool developed to protect the instream habitat from significant harm.
The water management districts in Florida are required by s. 373.042, F.S. to establish minimum flow and levels (MFLs) for a priority list of water bodies that is updated each year. These MFLs are established for water bodies to prevent “significant harm” to the water resources or ecology because of withdrawals for beneficial use, and can be an effective water resource management tool. Protection of the resource from significant harm is a benefit to the variety of existing users of the resource as well as the ecological systems supported by the water bodies. This article presents an overview of a modeling technique and an associated tool developed to protect the instream habitat from significant harm.Critical multi-stranded approach for determining the ecological values of diatoms in unique aquatic ecosystems of anthropogenic originhttps://peerj.com/preprints/277392019-09-272019-09-27Rafał M. OlszyńskiEwelina SzczepockaJoanna Żelazna-Wieczorek
Background. The ecological state of surface waters is typically assessed by a multi-aspect approach based on a determination of its chemical and physical parameters, by hydromorphology and the use of indicator organisms such as benthic diatoms. By assigning ecological indicator values, it is possible to create diatom indices which serve as the basic tool in assessing the ecological status of surface waters. These ecological indicator values are set according to classification systems, such as the Van Dam et al. 1994 system, which classifies species of diatoms according to seven different ecological factors. However, recent studies on the autecology of diatoms have shown the need to verify and establish new ecological indicator values. To this end, aquatic ecosystems are good environments to observe the range of tolerance of benthic diatoms to environmental conditions due to their unique physical and chemical parameters. The aim of the present study was to propose the establishment of new, or altered, ecological indicator values, according to Van Dam et al. classification, of species of diatoms characteristic of three post-mining aquatic ecosystems. Methods. In total, 36 species were identified that were characteristic of three waterbodies: a salt aquatic complex (water outflow, a drainage ditch and a pond), a mined iron ore reservoir and a mined lignite reservoir. Their ecological indicator values were calculated using OMNIDIA software, and the environmental conditions prevailing in the studied ecosystems were determined. Of the 36 characteristic species, 16 lacking at least one assigned ecological indicator value were analysed further. The analysis identified three groups of selected characteristic species which showed a correlation, or lack of such, to the tested physical and chemical parameters. Results. Based on this multistage study of the autecology of characteristic diatoms, comprising an analysis of environmental conditions, literature analysis and reference ecological indicator values of other species, it is proposed that 32 ecological indicator values be established or adjusted for 16 species, and that Planothidium frequentissimum be excluded from water quality assessments.
Background. The ecological state of surface waters is typically assessed by a multi-aspect approach based on a determination of its chemical and physical parameters, by hydromorphology and the use of indicator organisms such as benthic diatoms. By assigning ecological indicator values, it is possible to create diatom indices which serve as the basic tool in assessing the ecological status of surface waters. These ecological indicator values are set according to classification systems, such as the Van Dam et al. 1994 system, which classifies species of diatoms according to seven different ecological factors. However, recent studies on the autecology of diatoms have shown the need to verify and establish new ecological indicator values. To this end, aquatic ecosystems are good environments to observe the range of tolerance of benthic diatoms to environmental conditions due to their unique physical and chemical parameters. The aim of the present study was to propose the establishment of new, or altered, ecological indicator values, according to Van Dam et al. classification, of species of diatoms characteristic of three post-mining aquatic ecosystems. Methods. In total, 36 species were identified that were characteristic of three waterbodies: a salt aquatic complex (water outflow, a drainage ditch and a pond), a mined iron ore reservoir and a mined lignite reservoir. Their ecological indicator values were calculated using OMNIDIA software, and the environmental conditions prevailing in the studied ecosystems were determined. Of the 36 characteristic species, 16 lacking at least one assigned ecological indicator value were analysed further. The analysis identified three groups of selected characteristic species which showed a correlation, or lack of such, to the tested physical and chemical parameters. Results. Based on this multistage study of the autecology of characteristic diatoms, comprising an analysis of environmental conditions, literature analysis and reference ecological indicator values of other species, it is proposed that 32 ecological indicator values be established or adjusted for 16 species, and that Planothidium frequentissimum be excluded from water quality assessments.Using environmental DNA to monitor the reintroduction success of the Rhine sculpin (Cottus rhenanus) in a restored streamhttps://peerj.com/preprints/275742019-09-272019-09-27Christopher A HempelBianca PeinertArne J BeermannVasco ElbrechtJan-Niklas MacherTill-Hendrik MacherGunnar JacobsFlorian Leese
Freshwaters face some of the highest rates of species loss, caused by strong human impact. To decrease this strong impact, ecological restorations are increasingly applied to restore and maintain the natural ecological status of freshwaters. Their ecological status can be determined by assessing the presence of indicator species (e.g. certain fish species), which is called biomonitoring. However, traditional biomonitoring of fish, such as electrofishing, is often challenging and invasive. To augment traditional biomonitoring of fish, the analysis of environmental DNA (eDNA) has recently been proposed as an alternative, sensitive approach. The present study employed this modern approach to monitor the Rhine sculpin (Cottus rhenanus), a fish species that has been reintroduced into a recently restored stream within the Emscher catchment in Germany, in order to validate the success of the applied restorations and to monitor the species’ dispersal. We monitored the dispersal of the Rhine sculpin using replicated 12S end-point PCR eDNA surveillance at a fine spatial and temporal scale. In that way, we investigated if eDNA analysis can be applied for freshwater assessments. We also performed traditional electrofishing in one instance to validate our eDNA-based approach. We could track the dispersal of the Rhine sculpin and showed a higher dispersal potential of the species than we assumed. We validated the species’ dispersal across a potential dispersal barrier via eDNA detection and showed a steep increase of positive detections once the reintroduced population had established. In contrast to that, false negative eDNA results occurred at early reintroduction stages. Our results show that eDNA detection can be used to confirm and monitor reintroductions and to contribute to the assessment and modelling of ecological status of streams.
Freshwaters face some of the highest rates of species loss, caused by strong human impact. To decrease this strong impact, ecological restorations are increasingly applied to restore and maintain the natural ecological status of freshwaters. Their ecological status can be determined by assessing the presence of indicator species (e.g. certain fish species), which is called biomonitoring. However, traditional biomonitoring of fish, such as electrofishing, is often challenging and invasive. To augment traditional biomonitoring of fish, the analysis of environmental DNA (eDNA) has recently been proposed as an alternative, sensitive approach. The present study employed this modern approach to monitor the Rhine sculpin (Cottus rhenanus), a fish species that has been reintroduced into a recently restored stream within the Emscher catchment in Germany, in order to validate the success of the applied restorations and to monitor the species’ dispersal. We monitored the dispersal of the Rhine sculpin using replicated 12S end-point PCR eDNA surveillance at a fine spatial and temporal scale. In that way, we investigated if eDNA analysis can be applied for freshwater assessments. We also performed traditional electrofishing in one instance to validate our eDNA-based approach. We could track the dispersal of the Rhine sculpin and showed a higher dispersal potential of the species than we assumed. We validated the species’ dispersal across a potential dispersal barrier via eDNA detection and showed a steep increase of positive detections once the reintroduced population had established. In contrast to that, false negative eDNA results occurred at early reintroduction stages. Our results show that eDNA detection can be used to confirm and monitor reintroductions and to contribute to the assessment and modelling of ecological status of streams.The interplay between movement, dispersal and morphology in Tetrahymena ciliateshttps://peerj.com/preprints/265402019-09-032019-09-03Frank PennekampJean ClobertNicolas Schtickzelle
Understanding how and why individual movement translates into dispersal between populations is a long-term goal in ecology. Movement is broadly defined as “any change in the spatial location of an individual”, whereas dispersal is more narrowly defined as a movement that may lead to gene flow. Because the former may create the condition for the latter, behavioural decisions that lead to dispersal may be detectable in underlying movement behaviour. In addition, dispersing individuals also have specific sets of morphological and behavioural traits that help them coping with the costs of movement and dispersal, and traits that mitigate costs should be under selection and evolve if they have a genetic basis. Here we experimentally study the relationships between movement behaviour, morphology and dispersal across 44 genotypes of the actively dispersing unicellular, aquatic model organism Tetrahymena thermophila. We used two-patch populations to quantify individual movement trajectories, as well as activity, morphology and dispersal rate. First, we studied variation in movement behaviour among and within genotypes (i.e. between dispersers and residents) and tested whether this variation can be explained by morphology. Then, we address how much the dispersal rate is driven by differences in the underlying movement behaviour. Genotypes revealed clear differences in terms of movement speed and linearity. We also detected marked movement differences between resident and dispersing individuals, mediated by the genotype. Movement variation was partly explained by morphological properties such as cell size and shape, with larger cells consistently showing higher movement speed and higher linearity. Genetic differences in activity and diffusion rates were positively related to the observed dispersal and jointly explained 47% of the variation in dispersal rate. Our study shows that a detailed understanding of the interplay between morphology, movement and dispersal may have potential to improve dispersal predictions over broader spatio-temporal scales.
Understanding how and why individual movement translates into dispersal between populations is a long-term goal in ecology. Movement is broadly defined as “any change in the spatial location of an individual”, whereas dispersal is more narrowly defined as a movement that may lead to gene flow. Because the former may create the condition for the latter, behavioural decisions that lead to dispersal may be detectable in underlying movement behaviour. In addition, dispersing individuals also have specific sets of morphological and behavioural traits that help them coping with the costs of movement and dispersal, and traits that mitigate costs should be under selection and evolve if they have a genetic basis. Here we experimentally study the relationships between movement behaviour, morphology and dispersal across 44 genotypes of the actively dispersing unicellular, aquatic model organism Tetrahymena thermophila. We used two-patch populations to quantify individual movement trajectories, as well as activity, morphology and dispersal rate. First, we studied variation in movement behaviour among and within genotypes (i.e. between dispersers and residents) and tested whether this variation can be explained by morphology. Then, we address how much the dispersal rate is driven by differences in the underlying movement behaviour. Genotypes revealed clear differences in terms of movement speed and linearity. We also detected marked movement differences between resident and dispersing individuals, mediated by the genotype. Movement variation was partly explained by morphological properties such as cell size and shape, with larger cells consistently showing higher movement speed and higher linearity. Genetic differences in activity and diffusion rates were positively related to the observed dispersal and jointly explained 47% of the variation in dispersal rate. Our study shows that a detailed understanding of the interplay between morphology, movement and dispersal may have potential to improve dispersal predictions over broader spatio-temporal scales.Benchmarking protocols for the metagenomic analysis of stream biofilm viromeshttps://peerj.com/preprints/279142019-08-232019-08-23Meriem BeklizJade BrandaniMassimo BourquinTom BattinHannes Peter
Viruses drive microbial diversity, function and evolution and influence important biogeochemical cycles in aquatic ecosystems. Despite their relevance, we currently lack an understanding of their potential impacts on stream biofilm structure and function. This is surprising given the critical role of biofilms for stream ecosystem processes. Currently, the study of viruses in stream biofilms is hindered by the lack of an optimized protocol for their extraction, concentration and purification. Here, we evaluate a range of methods to separate viral particles from stream biofilms, and to concentrate and purify them prior to DNA extraction and metagenome sequencing. Based on epifluorescence microscopy counts of viral-like particles (VLP) and DNA yields, we optimize a protocol including treatment with tetrasodium pyrophosphate and ultra-sonication to disintegrate biofilms, tangential-flow filtration to extract and concentrate VLP, followed by ultracentrifugation in a sucrose density gradient to isolate VLP from the biofilm slurry. Viromes derived from biofilms sampled from three different streams were dominated by Siphoviridae, Myoviridae and Podoviridae and provide first insights into the viral diversity of stream biofilms. Our protocol optimization provides an important step towards a better understanding of the ecological role of viruses in stream biofilms.
Viruses drive microbial diversity, function and evolution and influence important biogeochemical cycles in aquatic ecosystems. Despite their relevance, we currently lack an understanding of their potential impacts on stream biofilm structure and function. This is surprising given the critical role of biofilms for stream ecosystem processes. Currently, the study of viruses in stream biofilms is hindered by the lack of an optimized protocol for their extraction, concentration and purification. Here, we evaluate a range of methods to separate viral particles from stream biofilms, and to concentrate and purify them prior to DNA extraction and metagenome sequencing. Based on epifluorescence microscopy counts of viral-like particles (VLP) and DNA yields, we optimize a protocol including treatment with tetrasodium pyrophosphate and ultra-sonication to disintegrate biofilms, tangential-flow filtration to extract and concentrate VLP, followed by ultracentrifugation in a sucrose density gradient to isolate VLP from the biofilm slurry. Viromes derived from biofilms sampled from three different streams were dominated by Siphoviridae, Myoviridae and Podoviridae and provide first insights into the viral diversity of stream biofilms. Our protocol optimization provides an important step towards a better understanding of the ecological role of viruses in stream biofilms.Example application of a continuous lake trophic state index on lakes with limited datahttps://peerj.com/preprints/279132019-08-212019-08-21Farnaz NojavanBetty J KreakieJeffrey W HollisterSong Qian
Lake trophic state indices have long been used to provide a measure of the trophic state of lakes. Over time it has been determined that these indices perform better when they utilize multiple metrics and provide a continuous measurement of trophic state. We utilize such a method for trophic state that is based upon a Proportional Odds Logistic Regression (POLR) model and extend this model with a Bayesian multilevel model that predicts nutrient concentrations from universally available GIS data. This Bayesian multilevel model provides relatively accurate measures of trophic state and has an overall accuracy of 60%. The approach illustrates a method for estimating a continuous, mutli-metric trophic state index for any lake in the United States. Future improvements to the model will focus on improving overall accuracy and use variables that are more sensitive to change over time.
Lake trophic state indices have long been used to provide a measure of the trophic state of lakes. Over time it has been determined that these indices perform better when they utilize multiple metrics and provide a continuous measurement of trophic state. We utilize such a method for trophic state that is based upon a Proportional Odds Logistic Regression (POLR) model and extend this model with a Bayesian multilevel model that predicts nutrient concentrations from universally available GIS data. This Bayesian multilevel model provides relatively accurate measures of trophic state and has an overall accuracy of 60%. The approach illustrates a method for estimating a continuous, mutli-metric trophic state index for any lake in the United States. Future improvements to the model will focus on improving overall accuracy and use variables that are more sensitive to change over time.Ecological networks reveal contrasting patterns of bacterial and fungal communities in glacier-fed streams in Central Asiahttps://peerj.com/preprints/278872019-08-082019-08-08Ze RenHongkai Gao
Bacterial and fungal communities in biofilms are important components in driving biogeochemical processes in stream ecosystems. Previous studies have well documented the patterns of bacterial alpha diversity in stream biofilms in glacier-fed streams, where, however, beta diversity of the microbial communities has received much less attention especially considering both bacterial and fungal communities. A focus on beta diversity can provide insights into the mechanisms driving community changes associated to large environmental fluctuations and disturbances, such as in glacier-fed streams. Moreover, modularity of co-occurrence networks can reveal more ecological and evolutionary properties of microbial communities beyond taxonomic groups. Here, integrating beta diversity and co-occurrence approach, we explored the network topology and modularity of the bacterial and fungal communities with consideration of environmental variation in glacier-fed streams in Central Asia. Combining results from hydrological modeling and normalized difference of vegetation index, this study highlighted that hydrological variables and vegetation status are major variables determining the environmental heterogeneity of glacier-fed streams. Bacterial communities formed a more complex and connected network, while the fungal communities formed a more clustered network. Moreover, the strong interrelations among the taxonomic dissimilarities of bacterial community and modules suggest they had common processes in driving diversity and taxonomic compositions across the heterogeneous environment. In contrast, fungal community and modules generally showed distinct driving processes to each other. Moreover, bacterial and fungal communities also had different driving processes. Furthermore, the variation of bacterial community and modules were strongly correlated with hydrological properties and vegetation status but not with nutrients, while fungal community and modules (except one module) were not associated with environmental variation. Our results suggest that bacterial and fungal communities had distinct mechanisms in structuring microbial networks, and environmental variation had strong influences on bacterial communities but not on fungal communities. The fungal communities have unique assembly mechanisms and physiological properties which might lead to their insensitive responses to environmental variations compared to bacterial communities. Overall, beyond alpha diversity in previous studies, these results add our knowledge that bacterial and fungal communities have contrasting assembly mechanisms and respond differently to environmental variation in glacier-fed streams.
Bacterial and fungal communities in biofilms are important components in driving biogeochemical processes in stream ecosystems. Previous studies have well documented the patterns of bacterial alpha diversity in stream biofilms in glacier-fed streams, where, however, beta diversity of the microbial communities has received much less attention especially considering both bacterial and fungal communities. A focus on beta diversity can provide insights into the mechanisms driving community changes associated to large environmental fluctuations and disturbances, such as in glacier-fed streams. Moreover, modularity of co-occurrence networks can reveal more ecological and evolutionary properties of microbial communities beyond taxonomic groups. Here, integrating beta diversity and co-occurrence approach, we explored the network topology and modularity of the bacterial and fungal communities with consideration of environmental variation in glacier-fed streams in Central Asia. Combining results from hydrological modeling and normalized difference of vegetation index, this study highlighted that hydrological variables and vegetation status are major variables determining the environmental heterogeneity of glacier-fed streams. Bacterial communities formed a more complex and connected network, while the fungal communities formed a more clustered network. Moreover, the strong interrelations among the taxonomic dissimilarities of bacterial community and modules suggest they had common processes in driving diversity and taxonomic compositions across the heterogeneous environment. In contrast, fungal community and modules generally showed distinct driving processes to each other. Moreover, bacterial and fungal communities also had different driving processes. Furthermore, the variation of bacterial community and modules were strongly correlated with hydrological properties and vegetation status but not with nutrients, while fungal community and modules (except one module) were not associated with environmental variation. Our results suggest that bacterial and fungal communities had distinct mechanisms in structuring microbial networks, and environmental variation had strong influences on bacterial communities but not on fungal communities. The fungal communities have unique assembly mechanisms and physiological properties which might lead to their insensitive responses to environmental variations compared to bacterial communities. Overall, beyond alpha diversity in previous studies, these results add our knowledge that bacterial and fungal communities have contrasting assembly mechanisms and respond differently to environmental variation in glacier-fed streams.Appetite regulating genes may contribute to herbivory versus carnivory trophic divergence in haplochromine cichlidshttps://peerj.com/preprints/278652019-07-162019-07-16Ehsan P AhiAnna DuenserPooja SinghWolfgang GesslChristian Sturmbauer
Feeding is a complex behaviour comprised of satiety control, foraging, ingestion and subsequent digestion. Cichlids from the East African Great Lakes are renowned for their diverse trophic specializations, largely predicated on highly variable jaw morphologies. Thus, most research has focused on dissecting the genetic, morphological and regulatory basis of jaw and teeth development in these species. Here for the first time we explore another aspect of feeding, the regulation of appetite related genes that are expressed in the brain and control satiety in cichlid fishes. Using qPCR analysis, we first validate stably expressed reference genes in the brain of six haplochromine cichlid species at the end of larval development prior to foraging. We next evaluate the expression of 16 appetite related genes in herbivorous and carnivorous species from the parallel radiations of Lake Tanganyika, Malawi and Victoria. Interestingly, we find increased expression of two anorexigenic genes, cart and npy2r, in the brain of carnivorous species in all the lakes. This supports the notion that herbivory compared to carnivory requires stronger appetite stimulation in order to feed larger quantity of food and to compensate for the relatively poorer nutritional quality of a plant- and algae-based diet. Our study contributes to the limited body of knowledge on the neurological circuitry that controls feeding transitions and adaptations and in cichlids and other teleosts.
Feeding is a complex behaviour comprised of satiety control, foraging, ingestion and subsequent digestion. Cichlids from the East African Great Lakes are renowned for their diverse trophic specializations, largely predicated on highly variable jaw morphologies. Thus, most research has focused on dissecting the genetic, morphological and regulatory basis of jaw and teeth development in these species. Here for the first time we explore another aspect of feeding, the regulation of appetite related genes that are expressed in the brain and control satiety in cichlid fishes. Using qPCR analysis, we first validate stably expressed reference genes in the brain of six haplochromine cichlid species at the end of larval development prior to foraging. We next evaluate the expression of 16 appetite related genes in herbivorous and carnivorous species from the parallel radiations of Lake Tanganyika, Malawi and Victoria. Interestingly, we find increased expression of two anorexigenic genes, cart and npy2r, in the brain of carnivorous species in all the lakes. This supports the notion that herbivory compared to carnivory requires stronger appetite stimulation in order to feed larger quantity of food and to compensate for the relatively poorer nutritional quality of a plant- and algae-based diet. Our study contributes to the limited body of knowledge on the neurological circuitry that controls feeding transitions and adaptations and in cichlids and other teleosts.Microbiome analysis of healthy and diseased sponges Lubomirskia baicalensis by using cell cultures of primmorphshttps://peerj.com/preprints/278512019-07-112019-07-11Lubov ChernogorElizabet KlimenkoIgor KhanaevSergei Belikov
Background. Freshwater sponges (Demosponges, Lubomirskiidae) are dominated in the littoral zone Lake Baikal in the biomass of benthic organisms and represent complex consortia of many species of eukaryotes and prokaryotes. A distinctive feature of sponges from Lake Baikal is their ability to live in symbiosis with various kinds of chlorophyll containing microalgae. Recently there have been massive diseases and the death of freshwater sponges. The etiology and ecology of these events remain unknown. Purpose. The purpose of the research was to use cell culture of primmorphs in vitro to study the microbiomes of healthy and diseased sponges to show the transmission of pathogenic agents from diseased sponges to cell cultures. Methods. The cell culture of primmorphs sponge Lubomirskia baicalensis was used to study microbiome communities in diseased and sick sponges in comparison with healthy sponge with subsequent sequencing of gene 16S rRNA and analysis of changes in microbiomes. Results. Results this study were show that use of cell culture of primmorphs in vitro is equivale of healthy sponge. Microbial community of healthy sponge and primmorphs was grouped separately from the community of diseased sponges and infected primmorphs, which confirms the suitability the cell culture of primmorphs, as a model sponge system. We found the mass death of green symbionts (Chlorophyta) and a shift in the microbial communities of sponges/primmorphs, associated with increase in relative abundant of different phyla Bacteroidetes and Proteobacteria with dominated families Flavobacteriaceae and Burkholderiaceae, Moraxellaceae in diseased sponges and infected cell cultures of primmorphs. Conclusions. This approach allowed us, using the cell culture of primmorphs, to identify potential opportunistic bacteria that can work together, which possibly enhances their action. The primmorphs system described here is a powerful new model system for studying basic mechanisms of the development of sponge disease, which will be valuable in future studies.
Background. Freshwater sponges (Demosponges, Lubomirskiidae) are dominated in the littoral zone Lake Baikal in the biomass of benthic organisms and represent complex consortia of many species of eukaryotes and prokaryotes. A distinctive feature of sponges from Lake Baikal is their ability to live in symbiosis with various kinds of chlorophyll containing microalgae. Recently there have been massive diseases and the death of freshwater sponges. The etiology and ecology of these events remain unknown. Purpose. The purpose of the research was to use cell culture of primmorphs in vitro to study the microbiomes of healthy and diseased sponges to show the transmission of pathogenic agents from diseased sponges to cell cultures. Methods. The cell culture of primmorphs sponge Lubomirskia baicalensis was used to study microbiome communities in diseased and sick sponges in comparison with healthy sponge with subsequent sequencing of gene 16S rRNA and analysis of changes in microbiomes. Results. Results this study were show that use of cell culture of primmorphs in vitro is equivale of healthy sponge. Microbial community of healthy sponge and primmorphs was grouped separately from the community of diseased sponges and infected primmorphs, which confirms the suitability the cell culture of primmorphs, as a model sponge system. We found the mass death of green symbionts (Chlorophyta) and a shift in the microbial communities of sponges/primmorphs, associated with increase in relative abundant of different phyla Bacteroidetes and Proteobacteria with dominated families Flavobacteriaceae and Burkholderiaceae, Moraxellaceae in diseased sponges and infected cell cultures of primmorphs. Conclusions. This approach allowed us, using the cell culture of primmorphs, to identify potential opportunistic bacteria that can work together, which possibly enhances their action. The primmorphs system described here is a powerful new model system for studying basic mechanisms of the development of sponge disease, which will be valuable in future studies.Reproductive biology of Hybopsis amblops, the Bigeye Chub, in the Flint River of Alabamahttps://peerj.com/preprints/267192019-07-042019-07-04Crissy L TarverBruce W Stallsmith
Background. The purpose of this study was to establish a reproductive schedule and examine reproductive traits that shape fecundity of the Bigeye Chub, Hybopsis amblops Cyprinidae, in the Flint River system of north Alabama.
Methods. Life history traits associated with reproduction, growth, and maturation were assessed. Fish collections were made monthly from August, 2013, through July, 2014.
Results. The Bigeye Chub in Alabama primarily spawns in April and May as indicated by gonadosomatic index (GSI), ovarian condition and clutch size. Average GSI values began to rise in February, peaked in April and May at over 13% for females and 1.6% for males, and showed a steep decline from May to June for both sexes. Average clutch size was highest in April at 812. Diameter of the most mature oocyte stage averaged 0.74 mm, relatively small compared to other cyprinids found in the Flint River.
Discussion. The Bigeye Chub’s relatively large clutch size as a measure of fecundity places the species intermediate between opportunistic and periodic in the trilateral life history scheme of Winemiller and Rose. The species is apparently responding to a flow regime with a defined seasonality as well as predictability of flow and resources.
Background. The purpose of this study was to establish a reproductive schedule and examine reproductive traits that shape fecundity of the Bigeye Chub, Hybopsis amblops Cyprinidae,in the Flint River system of north Alabama.Methods. Life history traits associated with reproduction, growth, and maturation were assessed. Fish collections were made monthly from August, 2013, through July, 2014.Results. The Bigeye Chub in Alabama primarily spawns in April and May as indicated by gonadosomatic index (GSI), ovarian condition and clutch size. Average GSI values began to rise in February, peaked in April and May at over 13% for females and 1.6% for males, and showed a steep decline from May to June for both sexes. Average clutch size was highest in April at 812. Diameter of the most mature oocyte stage averaged 0.74 mm, relatively small compared to other cyprinids found in the Flint River.Discussion. The Bigeye Chub’s relatively large clutch size as a measure of fecundity places the species intermediate between opportunistic and periodic in the trilateral life history scheme of Winemiller and Rose. The species is apparently responding to a flow regime with a defined seasonality as well as predictability of flow and resources.