Brachionus Plicatilis Research Articles

Combined toxic effects of yessotoxin and polystyrene on the survival, reproduction, and population growth of rotifer Brachionus plicatilis at different temperatures.

Yessotoxin (YTX) is a disulfated toxin produced by harmful dinoflagellates and causes risks to aquatic animals. Polystyrene (PS) microplastics could absorb toxins in seawaters but pose threats to organism growth. In this study, the combined toxic effects of YTX (0, 20, 50, and 100 µg L-1) and PS (0, 5, and 10 µg mL-1) on the survival, reproduction, and population growth of marine rotifer Brachionus plicatilis at 20 °C, 25 °C, and 30 °C were evaluated. Results indicated that the survival time (S), time to first batch of eggs (Ft), total offspring per rotifer (Ot), generational time (T0), net reproduction rate (R0), intrinsic growth rate (rm), and population growth rate (r) of rotifers were inhibited by YTX and PS at 25 °C and 30 °C. Low temperature (20 °C) improved the life-table parameters T0, R0, and rm at YTX concentrations less than 100 µg L-1. Temperature, YTX, and PS had interactive effects on rotifers' S, Ft, Ot, T0, R0, rm, and r. The combined negative effects of YTX and PS on rotifers' survival, reproduction, and population growth were significantly enhanced at 30 °C. These findings emphasized the importance of environmental temperature in studying the interactive effects of microplastics and toxins on the population growth of zooplankton in eutrophic seawaters.

UV-B radiation aging changed the environmental behavior of polystyrene micro-/nanoplastics-adsorption kinetics of BDE-47, plankton toxicities and joint toxicities with BDE-47

UV-B radiation acts as an important environmental factor for aging micro-/nanoplastics (MNPs) in the marine environments, while the effect of aged MNPs on plankton is lacking specific research. Referencing to the UV-B radiation intensity in natural environments (2.29W·m-2), we chose the floating polystyrene (PS) MNPs (50nm, 1 μm) as the research target in this study. The results indicated that UV-B radiation aging for 30 days led to a rougher surface, increased SBET, increased hydrophobicity, and decreased negative charges of PS MNPs. Correspondingly, aged MNPs increased their adsorption abilities for 2,2',4,4'-tetrabromodiphenyl ether (BDE-47), especially for the initial stage. After UV-B radiation aging processes, the individual toxicities of the two sized MNPs on Thalassiosira pseudonana and Brachionus plicatilis both increased, while their joint toxicities with BDE-47 decreased on T. pseudonana but increased on B. plicatilis. The changes in toxicity were more pronounced in 1 μm PS MNPs under air-aged conditions. This study provided the data basis for evaluating the changes of MNPs environmental behaviors under UV-B radiation in the marine environments, with important ecological significance.

Larval Rearing of the Giant Trevally, Caranx ignobilis (Forsskål, 1775), Fed Live Food Combinations of Rotifers, Copepods and Artemia salina

The giant trevally, Caranx ignobilis, is a high value fish which has been studied for spawning in captivity and domestication in the Philippines in view of its aquaculture potential. Initial larval rearing of the species encountered mortality issues, and this study attempts to address the problem to improve their survival. Hatchery-bred C. ignobilis larvae were reared for 40 days in nine units of 100 L conical fiberglass tanks at a stocking density of 500 larvae.tank-1 under three feed treatments with different combinations of rotifers (Brachionus plicatilis), brine shrimp (Artemia) and copepods (Pseudodiaptomus spp.): T1- Brachionus plicatilis + Artemia, T2- Brachionus plicatilis + Pseudodiaptomus spp., and T3-Brachionus plicatilis + Pseudodiaptomus spp. + Artemia fed at 0800 h and 1600 h. The results showed that the inclusion of copepods in the feeding regimen had positive effects on survival. Survival rate was significantly higher (P < 0.05) in T2 (23.47 ± 3.18 %) than T1 (11.67 ± 1.90 %) but was not statistically different from T3 (14.37 ± 3.88 %). Length increment was significantly different (P < 0.05) among treatments but with no statistical difference in specific growth rate (P > 0.05). The erratic swimming behaviour leading to mortality associated with insufficient levels of highly unsaturated fatty acids in Artemia was not observed in T2, thus, validating the assumption that the feeding with copepods will increase survival during larval rearing. The use of copepods for C. ignobilis larviculture is seen to play an important role in the success of the seed production protocol for this species. However, a sustainable supply of copepods through appropriate mass propagation techniques must be ensured to achieve higher production of C. ignobilis seeds in the hatcheries.

Rotifer detection and tracking framework using deep learning for automatic culture systems

Although rotifers (Brachionus plicatilis sp. complex) are an important first feed source in marine fish aquaculture, their management is quite time-consuming because their populations and movements need to be monitored daily. This management is still performed manually, and automation is required. If we could make good use of the recent breakthroughs in deep learning, the automating a rotifer culture system could be realized. We propose a deep learning framework for detecting and tracking rotifers as a basis for such automation and carefully verify its accuracy. Experimental results showed that a mean average precision of 88.5 % was achieved for detection, and a higher-order tracking accuracy of 88.7 % was achieved for tracking, indicating the suitability of deep learning methods for predicting the state of rotifers. In addition, this research will contribute to the development of the field by releasing the trained model and code for visualizing the tracking results, as well as an annotated dataset with over 30,000 instances.

Performance of growth on Trachinotus blochii larvae fed by Brachionus plicatilis enriched with eicosapentaenoic acid (EPA) and decosahexaenoic acid (DHA) extraction from Maggot black soldier fly (BSF)

Performance of growth on Trachinotus blochii larvae fed by Brachionus plicatilis enriched with eicosapentaenoic acid (EPA) and decosahexaenoic acid (DHA) extraction from Maggot black soldier fly (BSF)

Histological study of the development of the digestive system during larval feeding in the pike silverside Chirostoma estor.

Chirostoma estor (Jordan, 1879) is an endemic freshwater species with a high potential for aquaculture; however, as in many other fish, larviculture of this species is the most critical stage, in which the higher mortality rates. Therefore, it is necessary to fully describe the development of the digestive system to establish better feeding protocols in the larval culture of C. estor, both for aquaculture and restoration purposes. In the present study, larviculture was carried out from hatching to 20days after hatching (DAH). The organisms were fed with the rotifer Brachionus plicatilis from 2 to 14 DAH, and nauplii of Artemia sp. from 15 to 20 DAH. A total of 12 organisms (0, 3, 5, 10, 15, and 20 DAH) were taken for size and weight growth and histological and histochemical analysis. The histological analysis indicated that after 3 DAH, the opening of the mouth and anus was observed, coinciding with the beginning of exogenous feeding. In addition, the digestive system developed, with differentiation of the oropharyngeal sections, esophagus, and intestine, folding of the intestinal mucosa, as well as associated organs (liver and pancreas) that reach their maximum development at 20 DAH. Thus, C. estor at this stage of development can digest and absorb nutrients despite being an agastric fish. The results obtained in this study will facilitate a better understanding of the ontogenetic morphophysiological development processes, associated with the transition of larvae to exogenous feeding, which ensures a higher percentage of survival during larval development and of course, adds to the diversity ontogenetics of teleostean.

Reproductive toxicity of hexabromocyclododecane in rotifer Brachionus plicatilis: Involvement of reactive oxygen species and calcium signaling pathways

To assess the toxicity of Hexabromocyclododecane (HBCD), the population, individual, and cellular biochemical parameters of the rotifer Brachionus plicatilis exposed to different concentrations of HBCD were investigated. The results showed that the population growth rate, reproductive period, and offspring number in B. plicatilis significantly decreased under 324 μg/L and 648 μg/L HBCD. Antioxidant enzyme activity and mRNA expression of CAT and Mn-SOD were promoted at low concentrations (32 μg/L and 64 μg/L) and inhibited at high concentrations (324 μg/L and 648 μg/L), while MDA content accumulated continuously with increasing HBCD concentrations, indicating that HBCD induced oxidation imbalance in rotifers. Further evidence was provided by the correlation between DNA fragmentation and physiological changes. The increased intercellular concentration of Ca2+ and the expression of CaM mRNA suggested that HBCD activated pathways related to calcium signaling. In summary, the excessive production of ROS induced by HBCD was considered to be the main cause of reproductive toxicity.

Emerging threat of marine microplastics: Cigarette butt contamination on Yellow Sea beaches and the potential toxicity risks to rotifer growth and reproduction

Cigarette butts have become one of the most common and persistent forms of debris in marine coastal areas, where they pose significant toxicity risks. This study investigated cigarette butt pollution along beaches of the Yellow Sea and used laboratory experiments to assess the toxicity of their leachate and fibers on the euryhaline rotifer Brachionus plicatilis. A pollution index confirmed pollution by this debris across all eight beaches surveyed, where the density of cigarette butts averaged 0.23 butts/m2. In controlled laboratory experiments, both the fibers and leachates from cigarette butts exhibited negative impacts on the development, reproduction, and population growth of rotifers. Unique abnormalities observed under different exposure treatments indicated toxicity specific to certain chemicals and particles. Continuous exposure to cigarette butts initially reduced rotifer fecundity, but this effect diminished over successive generations. However, the exposure induced transgenerational reproductive toxicity in the rotifers. Adaptive responses in rotifers after repeated exposure led to relative reduction in reproductive inhibition in the F3 and F4 generations. Furthermore, rotifers were capable of ingesting and accumulating cigarette butts, and maternal transfer emerged as an alternative pathway for uptake of this material in the offspring. These results increase our understanding of the ecological risks posed by cigarette butts in aquatic environments.

Effect of alternative natural diet on microplastic ingestion, functional responses and trophic transfer in a tri-trophic coastal pelagic food web

The patchy distribution of microplastics (MP) and their size range similar to planktonic organisms, are likely to have major ecological consequences, through MP ingestion, food dilution, and transfer across trophic levels. Our study applied a community module using tritrophic food chain with zooplankton as prey, and a planktivorous seabass fry as predator. We conducted a series of feeding experiments and recorded the direct uptake of MP under six different concentrations ranging from 25 to 800 particles L−1. We also estimated the indirect transfer of MP via trophic link. The ingestion rates for Brachionus plicatilis, Mesocyclops isabellae, and Lates calcarifer, were 3.7 ± 0.3 MP ind−1 min−1, 1.69 ± 0.1 MP ind−1 min−1, and 3.51 ± 0.52 MP ind−1 h−1, respectively. In the presence of a natural diet, rotifers and copepods ingested significantly lower number, whereas, fish fry ingested a higher number of MP, suggesting further vulnerability to the consumers of MP-contaminated fish and potential biomagnification at higher trophic levels. Overall, the MP uptake rate increased with increasing concentration, and finally leveled off, indicating a type II functional response to MP concentration. The presence of natural diet led to a lower Km value. In the indirect transfer experiment, 74 % of B. plicatilis and 78 % of M. isabellae individuals were contaminated with MP, when offered as prey. Brachionid mastax and MP particles were observed in the gut of copepods. The fish fry gut content also recorded brachionid mastax, MP-contaminated copepods, and MP particles, showing direct evidence of trophic transfer pointing to a cascading effect on higher trophic levels including humans via piscivory.

Allelochemicals determine competition and grazing control in Alexandrium catenella

The production of allelochemicals by the toxigenic dinoflagellate Alexandrium catenella is one of the suggested mechanisms to facilitate its bloom formation and persistence by outcompeting other phototrophic protists and reducing grazing pressure. In Southern California, toxic events caused by A. catenella and paralytic shellfish toxins (PSTs) regularly impact coastal ecosystems; however, the trophic interactions and mechanisms promoting this species in a food web context are still not fully understood. In the present study, we combined a dynamical mathematical model with laboratory experiments to investigate potential toxic and allelochemical effects of an A. catenella strain isolated off the coast of Los Angeles, Southern California, on competitors and a common zooplankton consumer. Experiments were conducted using three toxigenic strains of A. catenella, comparing the new Californian isolate (Alex Cal) to two strains previously described from the North Sea, a lytic (Alex2) and non-lytic (Alex5) strain, testing for donor density-dependent effects on two phytoplankton species (Rhodomonas salina, Tetraselmis sp.) and on the rotifer Brachionus plicatilis. Bioassays revealed a steep decline in competitor and consumer populations with increasing Alex Cal concentrations, indicating an intermediate lytic activity compared to the North Sea strains (lytic Alex2 and non-lytic Alex5). The rotifer fed and grew well on the PST- toxic, but non-lytic Alex5 strain, while its survival significantly decreased with increasing concentrations of the two lytic strains Alex Cal and Alex 2, indicating that negative effects on the rotifer were mediated by allelochemicals rather than PST-toxins. Mixed culture experiments including both competitors and consumers demonstrated that the intensity of allelochemical effects not only depended on the A. catenella density but also on the target density. Negative effects on grazers were alleviated by co-occurring competitors with a lower sensitivity to allelochemicals, thus reducing harmful compounds and allowing grazing control on the dinoflagellate to come into effect again. Results from mixed culture experiments were supported by the mathematical approach used in this study which was calibrated with data from simple monoculture growth, pairwise competition and predator-prey experiments, demonstrating the applicability of this model approach to predict the outcome of more complex food web dynamics at the community level.

Effects of microplastics on reproductive characteristics and mechanisms of the marine rotifer Brachionus plicatilis

Microplastic pollution, especially secondary microplastics (MPs), poses a significant threat to marine ecosystems. Despite its prevalence, the impact of natural-aged MPs on marine organisms, hindered by collection challenges, remains poorly understood. This study focused on 1–3 μm natural-aged MPs collected from Japan's coastal sea, investigating their effects on the rotifer Brachionus plicatilis sensu stricto and its reproductive mechanisms. Rotifers exposed to varying MP concentrations (0, 20, and 200 particles/mL) over 14-day batch cultures exhibited reduced population growth and fertilization rates. Down-regulation of reproductive genes and up-regulation of oxidative stress-related genes were observed, indicating MP-induced disruptions. Enhanced activities of superoxide dismutase and acetylcholinesterase and elevated malondialdehyde levels further emphasized oxidative stress. These findings underscore the detrimental impact of MPs on rotifer reproductivity, shedding light on the underlying mechanisms.

Effects on fatty acids, biochemical composition and growth of rotifer (Brachionus plicatilis) fed with different concentrations of Nannochloropsis sp.

The density of microalgae and nutrient content have impact on the population growth rate, egg rate and nutritional values of rotifers. The aim of this study was to investigate the effects of different concentrations of the alga Nannochloropsis sp. (N10: 10x106, N20: 20x106, N30: 30x106 cells mL-1) on the growth, egg rate, biochemical composition and fatty acid profile of the rotifer Brachionus plicatilis. To maintain a consistent algae density, an equivalent quantity was supplemented to compensate for any reduction. The study was started with three replicates, each with an initial inoculation density of 200 Brachionus individuals mL-1 . The investigation spanned 5 days, during which population parameters (total number of individuals, proportion of individuals with eggs and growth rate) were calculated. After the study period, rotifers were harvested for subsequent biochemical and fatty acid analyses. Notably, the N30 group showed the highest proportions of crude protein (54.41%) and crude lipid (34.5%). The N20 group displayed the most substantial content of total fatty acids, recording a value of 70.69%. Consequently, the N30 group, with a concentration of 30x106 cells mL-1, emerged as the most proficient group, demonstrating superior performance in both population growth and biochemical composition.

Multigenerational resilience of the marine rotifer Brachionus plicatilis to high temperature after additive exposure to high salinity and nanoplastics

To study multigenerational resilience to high temperature (HT) conditions, we exposed Brachionus plicatilis marine rotifers to HT, high salinity (HS), and nanoplastics (NPs), and measured reproductive and life-cycle endpoints. After exposure to HT, rotifer lifespans were reduced, but daily production of offspring increased. However, both combined HT/HS and HT/HS/NP exposure led to additional decreases in longevity and reproductive ability; the antioxidant defense mechanisms of the rotifers were also notably upregulated as measured by reactive oxygen species levels. Fatty-acid profiles were reduced in all conditions. In multigenerational experiments, the negative effects of HT dissipated rapidly; however, the effects of HT/HS and HT/HS/NPs required four generations to disappear completely. The findings indicated that B. plicatilis were able to recover from these environmental stressors. This study demonstrated the resilience of aquatic organisms in response to changing environmental conditions and provides insights into the complex interactions of different abiotic stressors.

Effects of bisphenol A on reproduction, oxidative stress, and lipid regulation in the marine rotifer Brachionus plicatilis

This study reports the effects of bisphenol A (BPA) on the rotifer Brachionus plicatilis, focusing on growth performance, reproductive output, oxidative stress responses, and lipid metabolism genes. High BPA levels disrupted peak daily offspring production and led to oxidative stress and increased superoxide dismutase and catalase activity. The research identified distinctive monoacylglycerol O-acyltransferase (MGAT) and diacylglycerol O-acyltransferase (DGAT) genes in B. plicatilis, B. rotundiformis, and B. koreanus, enhancing understanding of lipid metabolism in these species. BPA exposure significantly altered MGAT and DGAT expression, and feeding status affected these regulatory patterns. When food was unavailable, BPA reduced DGAT2 and MGAT2a expression. However, under feeding conditions, DGAT2 and MGAT1 levels increased, indicating that nutritional status and BPA exposure interact to affect gene expression.

The impact of artificial light pollution at night on the life history parameters of rotifer Brachionus plicatilis with different food experiences

Artificial light at night (ALAN) may pose threat to rotifer Brachionus plicatilis. Additionally, the food of rotifer, i.e. algal community composition, often fluctuates. Thus, we selected five wavelengths of ALAN (purple, blue, green, red, white) and a three-colored light flashing mode (3-Flash) to test their impacts on life history traits of B. plicatilis with different food experiences, including those feeding Chlorella vulgaris (RC) or Phaeocystis globosa (RP). Results indicated purple ALAN promoted RC development, white ALAN inhibited RC development, while 3-Flash and white ALAN promoted RP development. Under red and white ALAN, RP increased fecundity but decreased lifespan. High-quality food enhanced rotifer's resistance to the impact of ALAN on lifespan. ALAN and food experience interacted on B. plicatilis. The effect of blue ALAN has less negative effects on B. plicatilis, based on hierarchical cluster analysis. Such findings are helpful to evaluate the potential impact of ALAN on marine zooplankton.

Energy strategy alteration, rather than toxicity itself, interferes with the population fluctuation of Brachionus plicatilis exposed to water-accommodated fractions (WAFs) of crude oil

Oil spills are reported to have conflicting impacts of either injury or resilience on zooplankton communities, and physiological plasticity is speculated to be the possible causative factor. But how? An explanation was sought by exposing the marine rotifer Brachionus plicatilis to a series of water-accommodated fractions (WAFs) of crude oil under controlled laboratory conditions, and population dynamics, which is the core issue for zooplankton facing external stress, were analyzed. The total hydrocarbon concentration of WAFs was quickly degraded from a concentration of 5.0 mg L−1 to half within 24 h and then remained stable. No acute lethality was observed; only motion inhibition was observed in the group treated with 10 %, 50 % and 100 % WAFs, which occurred simultaneously with inhibition of feeding and filtration. However, sublethal exposure to the WAFs concentration series presented stimulation impacts on reproduction and even the population of B. plicatilis. The negative correlation between motion and reproduction seemed to indicate that a shift in the distribution of individual energy toward reproduction rather than motion resulted in increased reproduction after exposure to WAFs. More evidence from transmission electron microscopy (TEM) revealed ultrastructural impairment in both the ovaries and cilia in each treated group, and imbalance in mitochondrial numbers was one of the distinct features of alteration. WAFs stress may alter the energy utilization and storage paradigm, as indicated by the significant elevation in glycogen and the significant decrease in lipid content after WAFs exposure. Further evidence from metabolomics analysis showed that WAFs stress increased the level of lipid metabolism and inhibited some of the pathways in glucose metabolism. Sublethal acute toxicity was observed only in the first 24 h with WAFs exposure, and an energy strategy consisting of changes in the utilization and storage paradigm and reallocation is responsible for the population resilience of B. plicatilis during oil spills.

New insights into the impact of leachates from in-field collected plastics on aquatic invertebrates and vertebrates

The impact of leachates from micronized beached plastics of the Mediterranean Sea and Atlantic Ocean on coastal marine ecosystems was investigated by using a multidisciplinary approach. Chemical analysis and ecotoxicological tests on phylogenetically distant species were performed on leachates from the following plastic categories: bottles, pellets, hard plastic (HP) containers, fishing nets (FN) and rapido trawling rubber (RTR). The bacteria Alivibrio fischeri, the nauplii of the crustaceans Amphibalanus amphitrite and Acartia tonsa, the rotifer Brachionus plicatilis, the embryos of the sea urchin Paracentrotus lividus, the ephyrae of the jellyfish Aurelia sp. and the larvae of the medaka Oryzias latipes were exposed to different concentrations of leachates to evaluate lethal and sub-lethal effects. Thirty-one additives were identified in the plastic leachates; benzophenone, benzyl butyl phthalate and ethylparaben were present in all leachates. Ecotoxicity of leachates varied among plastic categories and areas, being RTR, HP and FN more toxic than plastic bottles and pellets to several marine invertebrates. The ecotoxicological results based on 13 endpoints were elaborated within a quantitative weight of evidence (WOE) model, providing a synthetic hazard index for each data typology, before their integrations in an environmental risk index. The WOE assigned a moderate and slight hazard to organisms exposed to leachates of FN and HP collected in the Mediterranean Sea respectively, and a moderate hazard to leachates of HP from the Atlantic Ocean. No hazard was found for pellet, bottles and RTR. These findings suggest that an integrated approach based on WOE on a large set of bioassays is recommended to get a more reliable assessment of the ecotoxicity of beached-plastic leachates. In addition, the additives leached from FN and HP should be further investigated to reduce high concentrations and additive types that could impact marine ecosystem health.

Toxicity toward freshwater and marine water organisms of the cytostatic drugs bleomycin and vincristine and their binary mixture

Antineoplastic drugs are not effectively removed by wastewater treatment plants, ending up in surface waters. Since these drugs can interfere with the structure and functions of DNA, they pose a potential threat to aquatic biota. Unfortunately, many chemotherapeutic agents have not been studied in an environmental context. Additionally, there is a significant lack of information about the impact of anticancer drugs on marine organisms compared to freshwater species, and most studies only focus on the toxicity of single compounds rather than considering their occurrence as complex mixtures in the environment. Therefore, the aim of this study was to evaluate the ecotoxicity of two commonly used cytostatics, bleomycin and vincristine, toward six biomodels: Pseudokirchneriella subcapitata, Phaeodactylum tricornutum, Brachionus plicatilis, Brachionus calyciflorus, Thamnocephalus platyurus, and Artemia franciscana. These selected aquatic organisms are representatives of both freshwater and marine environments and belong to different trophic levels. The pharmaceuticals were investigated both individually and in combination. Binary mixture toxicity predictions were performed according to the Response Additivity and Independent Action models. Additionally, the toxicity data obtained from these experiments were utilized for risk assessment in the context of the drugs' environmental occurrence. The results indicated that freshwater species were generally more sensitive to both tested compounds than marine organisms, with T. platyurus being the most sensitive. Based on the tests performed on this biomodel, bleomycin was categorized as extremely toxic, while vincristine was considered moderately toxic. Neither of the applied models suitably predicted binary mixture toxicity, as the combination of drugs showed additive, synergistic, and antagonistic effects, suggesting that single compound toxicity data are insufficient for predicting the aquatic toxicities of cytostatics mixtures. The environmental risk of vincristine ranged from low to high, and for bleomycin varied from moderate to high, depending on the matrices examined. Therefore, further research on drug removal is recommended.

Antimicrobial Activity, Genetic Relatedness, and Safety Assessment of Potential Probiotic Lactic Acid Bacteria Isolated from a Rearing Tank of Rotifers (Brachionus plicatilis) Used as Live Feed in Fish Larviculture.

Aquaculture is a rapidly expanding agri-food industry that faces substantial economic losses due to infectious disease outbreaks, such as bacterial infections. These outbreaks cause disruptions and high mortalities at various stages of the rearing process, especially in the larval stages. Probiotic bacteria are emerging as promising and sustainable alternative or complementary strategies to vaccination and the use of antibiotics in aquaculture. In this study, potential probiotic candidates for larviculture were isolated from a rotifer-rearing tank used as the first live feed for turbot larvae. Two Lacticaseibacillus paracasei and two Lactiplantibacillus plantarum isolates were selected for further characterization due to their wide and strong antimicrobial activity against several ichthyopathogens, both Gram-positive and Gram-negative. An extensive in vitro safety assessment of these four isolates revealed the absence of harmful traits, such as acquired antimicrobial resistance and other virulence factors (i.e., hemolytic and gelatinase activities, bile salt deconjugation, and mucin degradation, as well as PCR detection of biogenic amine production). Moreover, Enterobacterial Repetitive Intergenic Consensus-PCR (ERIC-PCR) analyses unveiled their genetic relatedness, revealing two divergent clusters within each species. To our knowledge, this work reports for the first time the isolation and characterization of Lactic Acid Bacteria (LAB) with potential use as probiotics in aquaculture from rotifer-rearing tanks, which have the potential to optimize turbot larviculture and to introduce novel microbial management approaches for a sustainable aquaculture.

Maternal age effects on offspring lifespan and reproduction vary within a species.

Across diverse taxa, offspring from older mothers have decreased lifespan and fitness. Little is known about the extent to which maternal age effects vary among genotypes for a given species, however, except for studies of a few arthropod species. To investigate the presence and degree of intraspecific variability in maternal age effects, we compared lifespan, reproductive schedule, and lifetime reproductive output of offspring produced by young, middle-aged, and old mothers in four strains of rotifers in the Brachionus plicatilis species complex. We found significant variability among strains in the magnitude and direction of maternal age effects on offspring life history traits. In one strain, offspring of young mothers lived 20% longer than offspring of old mothers, whereas there were no significant effects of maternal age on lifespan for other strains. Depending on strain, advanced maternal age had positive effects, negative effects, or no effect on lifetime reproductive output. Across strains, older mothers produced offspring that had higher maximum daily reproduction early in life. The effects of maternal age on offspring vital rates could not be explained by changes in trade-offs between lifespan and reproduction. This study documents intraspecific variability in maternal age effects in an additional clade. Investigating intraspecific variability is critical for understanding the ubiquity of maternal age effects and their role in the evolution of life history and aging.