Copepod females invest a quantity of resources in their reproduction. Depending on several biotic and abiotic factors and their evolutionary history a trade-off can be commonly observed between ...producing a large number of smaller offspring or a small number of larger offspring. In this study, a multi-generational approach was applied to determine whether a trade-off between clutch size and egg size existed in the copepod Eurytemora affinis under different controlled conditions of temperature and salinity. This protocol was based on the follow-up of reproductive (Clutch Size 'CS', Egg Diameter 'ED') and morphological (Prosome Length 'PL') traits during several generations. Copepods were acclimated to cold (7 °C) and warm (20 °C) temperatures, and then their reproductive output was tested at the higher temperature of 24 °C. CS and ED were positively correlated to PL, so as a first step linear regressions between each reproductive trait and female PL were performed. The residuals from the regression lines of CS and ED with PL were calculated to remove the effect of female size. When the normalized data (residuals) of CS and ED plotted together a negative relationship between egg size and egg number revealed the existence of a trade-off. Copepod populations initially acclimated to cold temperature are commonly characterized by relatively smaller CS and larger ED. Conversely, warm temperature adapted females produced relatively larger CS and smaller ED. After transfer to a temperature of 24 °C, the ED did not change but the CS showed high variability indicating stressful conditions and no trade-off was observed. These observations suggest that E. affinis is able to modulate its reproduction depending on the encountered temperature. It seems that this copepod species can shift between a K- and an r-strategy in response to colder or warmer conditions. In a late winter-early spring like cold temperature, copepod females seem to invest more on offspring quality by producing relatively larger eggs. This ecological strategy ensures a high recruitment of the spring generation that is responsible for the strength of the maximum population size usually observed in late spring-early summer (May-June). To the contrary, at summer-like temperature, where the population density decreases significantly in the Seine estuary, copepod females seem to switch from K to r strategy by favoring offspring number compared to offspring size. Finally, the use of a higher temperature of 24 °C seems to disrupt the observed reproductive trade-off even after several generations. These results suggest that a switching between K- or r-strategy of E. affinis depends highly on temperature effects. The effect of salinity increase during a summer-like temperature of 20 °C as well as after transfer to 24 °C decreased PL and CS but the ED did not change significantly.
During an investigation program of faunal diversity in the shallow reef zone of the active volcanic island off northeastern Taiwan in July and September 2020, numerous individuals of the starfish ...Echinaster luzonicus (Gray, 1840) were found, and some individuals were found with associated symbionts. Starfish sampling in the 150-m coral reef zone was undertaken at a depth of 8 m through scuba diving. For each type of potential macrosymbiont, both the dorsal and ventral sides were carefully examined. The prevalence of macrosymbionts on the starfish E. luzonicus was recorded. The most common symbiotic organism on E. luzonicus was the ectoparasitic snail Melanella martinii (A. Adams in Sowerby, 1854), followed by the pontoniine shrimp Zenopontonia soror (Nobili, 1904) and the rare polychaete scaleworm Asterophilia carlae Hanley, 1989. The prevalence ratio with host E. luzonicus was low and varied by 8.62% and 4.35%, 6.03% and 0%, and 0.86% and 0.72% in July and September 2020 for M. martinii, Z. soror, and A. carlae, respectively. The present study is the first to discover the scaleworm A. carlae as a macrosymbiont of the tropical starfish E. luzonicus, with a widespread distribution, off Taiwan's northeastern coast, an area influenced by the Kuroshio Current.
Microbial secondary metabolites from extreme environments like hydrothermal vents are a promising source for industrial applications. In our study the protease gene from Bacillus cereus obtained from ...shallow marine hydrothermal vents in the East China Sea was cloned, expressed and purified. The protein sequence of 38 kDa protease SLSP-k was retrieved from mass spectrometry and identified as a subtilisin serine proteinase. The novel SLSP-k is a monomeric protein with 38 amino acid signal peptides being active over wide pH (7-11) and temperature (40-80 °C) ranges, with maximal hydrolytic activities at pH 10 and at 50 °C temperature. The hydrolytic activity is stimulated by Ca
, Co
, Mn
, and DTT. It is inhibited by Fe
, Cd
, Cu
, EDTA, and PMSF. The SLSP-k is stable in anionic, non-anionic detergents, and solvents. The ability to degrade keratin in chicken feather and hair indicates that this enzyme is suitable for the degradation of poultry waste without the loss of nutritionally essential amino acids which otherwise are lost in hydrothermal processing. Therefore, the proteinase is efficient in environmental friendly bioconversion of animal waste into fertilizers or value added products such as secondary animal feedstuffs.
Microbes or parasites spread vector-borne diseases by mosquitoes without being affected themselves. Insecticides used in vector control produce a substantial problem for human health. This study ...synthesized zinc oxide nanoparticles (ZnO NPs) using Lawsonia inermis L. and were characterized by UV-vis, FT-IR, SEM with EDX, and XRD analysis. Green synthesized ZnO NPs were highly toxic against Anopheles stephensi, whose lethal concentrations values ranged from 5.494 ppm (I instar), 6.801 ppm (II instar), 9.336 ppm (III instar), 10.736 ppm (IV instar), and 12.710 ppm (pupae) in contrast to L. inermis treatment. The predation efficiency of the teleost fish Gambusia affinis and the copepod Mesocyclops aspericornis against A. stephensi was not affected by exposure at sublethal doses of ZnO NPs. The predatory potency for G. affinis was 45 (I) and 25.83% (IV), copepod M. aspericornis was 40.66 (I) and 10.8% (IV) while in an ZnO NPs contaminated environment, the predation by the fish G. affinis was boosted to 71.33 and 34.25%, and predation of the copepod M. aspericornis was 60.35 and 16.75%, respectively. ZnO NPs inhibited the growth of several microbial pathogens including the bacteria (Escherichia coli and Bacillus subtilis) and the fungi (Alternaria alternate and Aspergillus flavus), respectively. ZnO NPs decreased the cell viability of Hep-G2 with IC
value of 21.63 µg/mL (R
= 0.942; P < 0.001) while the concentration increased from 1.88 to 30 µg/mL. These outcomes support the use of L. inermis mediated ZnO NPs for mosquito control and drug development.
Multiple stressors like metal toxicity, organic compounds and sediment pollution from the Seine estuary are raising concern and novel toxicological approaches are needed to better assess and monitor ...the risk. In the present study, the copepod Eurytemora affinis from the Seine, was exposed to two different sources of contaminants, which were resuspended polluted sediments and a mixture of trace metals (dissolved phase). The exposure continued for four generations (F0, F1, F2, F3) where F0 is a generation for acclimation to the exposure condition and F3 is a generation for decontamination followed without any exposure, to detect possible maternal carryover effects of pollutants (F0 – F2) and the role of recovery (in F3). Higher accumulation of metals resulted in higher mortalities at both exposure conditions, with particularly F1 being the most sensitive generation showing highest bioaccumulation of metals, highest mortality, and smallest population size. Copper accumulation was highest of all metals in mixture from both the resuspended sediment and the combined trace metal treatment. A significantly lower naupliar production was seen in copepods exposed to resuspended sediment compared to trace metal exposed copepods. However, the decontamination phase (F3) indicated that E. affinis pre-exposed to resuspended sediment had a higher ability to recover the total population size, increase naupliar production, and depurate accumulated Cu. The population exposed to a trace metal mixture showed lower recovery and lower ability to discharge accumulated toxic metals indicating its greater effect on our experimental model when compared to resuspended sediment.
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•Intergenerational exposure to trace metals and sediments caused highest mortality in F1.•F2 showed lower mortality indicating acclimation from the pre-exposed generation F1.•Naupliar production in F1 and F2 was lower at sediment than at metal exposure.•F3 (decontamination) showed enhanced recovery from sediment than from trace metal.•Maternal exposure to sediment produced more resistant offspring than metal exposure.
The bioindicator copepod Eurytemora affinis accumulated various trace metals from resuspended sediment and seawater, which reduced its population size upon chronic intergenerational exposure. However, decontamination phase produced more resistant offspring from sediment-exposed parents than trace metal mixed seawater promoting the need to study the various pathways of exposure over several generations.
The effect of exposure from several compartments of the environment at the level of individuals was rarely investigated. This study reports the effect of contaminants from varied compartments like ...sediment resuspension, elutriation from resuspended sediment (extract) and seawater spiked trace metal mixtures (TM) on morphological and reproductive traits of the pelagic bioindicator copepod Eurytemora affinis. At the population level of E. affinis, lowest survival was observed in dissolved exposures (TM and extract) in the first generation (G1), showing some adaptation in the second generation (G2). An opposite trend for resuspended sediment showed higher sensitivity in survival at G2. At the individual level, prosome length and volume proved to be sensitive parameters for resuspended sediments, whereas clutch size and egg diameter were more sensitive to TM and extract. Although the generation of decontamination (G3, no exposure), showed a significant recovery at the population level (survival % along with clutch size) of E. affinis exposed to resuspended sediment, morphological characteristics like prosome length and volume showed no such recovery (lower than control, p < 0.05). To the contrary, dissolved exposure showed no significant recovery from G1 to G3 on neither survival %, clutch size, egg diameter, prosome volume, but an increase of prosome length (p < 0.05). Such tradeoffs in combatting the stress from varied sources of toxicity were observed in all exposures, from G1 to G3. The number of lipid droplets inside the body cavity of E. affinis showed a significant positive correlation with trace metal bioaccumulation (p < 0.01) along with a negative correlation (p < 0.05) with survival and clutch size in each treatment. This confirms the inability of copepods to utilize lipids under stressful conditions. Our study tenders certain morphological and reproductive markers that show specificity to different compartments of exposure, promising an advantage in risk assessment and fish feed studies.
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•Contrasting sensitivity appeared between exposure compartments and generations.•Prosome length and volume were more sensitive to sediment resuspension.•Clutch size and egg diameter were more sensitive to dissolved exposure.•Seawater spiked trace metal mixtures provided lowest survival.•Trace metal and lipid droplet accumulation correlated significantly.
•Biosynthesized gold nanoparticles (AuN) were studied by FTIR, TEM, EDX and XRD.•LC50 of AuN vs. Anopheles stephensi and Aedes aegypti ranged from 18.8 to 41.5 ppm.•Copepod predation vs. A. stephensi ...and A. aegypti young larvae were 26.8% and 56%.•In AuN-treated sites, predation was 45.6% (A. stephensi ) and 77.3% (A. aegypti).•Low doses of AuN may boost the control of mosquito larvae in biocontrol programs.
Plant-borne compounds can be employed to synthesize mosquitocidal nanoparticles that are effective at low doses. However, how they affect the activity of mosquito predators in the aquatic environment is unknown. In this study, we synthesized gold nanoparticles (AuN) using the leaf extract of Cymbopogon citratus, which acted as a reducing and capping agent. AuN were characterized by a variety of biophysical methods and sorted for size in order to confirm structural integrity. C. citratus extract and biosynthesized AuN were tested against larvae and pupae of the malaria vector Anopheles stephensi and the dengue vector Aedes aegypti. LC50 of C. citratus extract ranged from 219.32 ppm to 471.36 ppm. LC50 of AuN ranged from 18.80 ppm to 41.52 ppm. In laboratory, the predatory efficiency of the cyclopoid crustacean Mesocyclops aspericornis against A. stephensi larvae was 26.8% (larva I) and 17% (larva II), while against A. aegypti was56% (I) and 35.1% (II). Predation against late-instar larvae was minimal. In AuN-contaminated environment,predation efficiency against A. stephensi was 45.6% (I) and 26.7% (II), while against A. aegypti was 77.3% (I) and 51.6% (II). Overall, low doses of AuN may help to boost the control of Anopheles and Aedes larval populations in copepod-based control programs.
Among territorial animals, several species are characterized by males showing the same initial behaviours towards both sexes, leading to significant chances of injuries against conspecifics. In this ...study, we investigated how visual stimuli exhibited by a female-mimicking robotic replica can be exploited by highly territorial
Betta splendens
males to discriminate males from females. In addition, we tested the effect of light stimuli, mimicking the colour pattern of a reproductive female, on the consistence of courtship displays in
B. splendens
males. The intensity of male behaviours used in both courtship and not-physical agonistic interactions (e.g. fin spreading and gill flaring) was not importantly modulated by different stimuli. Conversely, behavioural displays used specifically in male–female interactions significantly increased when the robotic replica colour pattern mimicked a reproductive female. Furthermore, male courtship behaviours obtained in response to the robotic replica exhibiting light stimuli were comparable with responses towards authentic conspecific females. Our biomimetic approach to establish animal–robot individual interaction can represent an advanced strategy for trait-based ecology investigation, a rapidly developing research field.
The traditional approach for biodegradation of organic matter in sewage treatment used a consortium of bacterial spp. that produce untreated or partially treated inorganic contaminants resulting in ...large amounts of poor-quality sludge. The aeration process of activated sludge treatment requires high energy. So, a sustainable technique for sewage treatment that could produce less amount of sludge and less energy demanding is required for various developed and developing countries. This led to research into using microalgae for wastewater treatment as they reduce concentrations of nutrients like inorganic nitrates and phosphates from the sewage water, hence reducing the associated chemical oxygen demand (COD). The presence of microalgae removes nutrient concentration in water resulting in reduction of chemical oxygen demand (COD) and toxic heavy metals like Al, Ni, and Cu. Their growth also offers opportunity to produce biofuels and bioproducts from algal biomass. To optimize use of microalgae, technologies like high-rate algal ponds (HRAPs) have been developed, that typically use 22% of the electricity used in Sequencing Batch Reactors for activated sludge treatment with added economic and environmental benefits like reduced comparative operation cost per cubic meter, mitigate global warming, and eutrophication potentials. The addition of suitable bacterial species may further enhance the treatment potential in the wastewater medium as the inorganic nutrients are assimilated into the algal biomass, while the organic nutrients are utilized by bacteria. Further, the mutual exchange of CO
and O
between the algae and the bacteria helps in enhancing the photosynthetic activity of algae and oxidation by bacteria leading to a higher overall nutrient removal efficiency. Even negative interactions between algae and bacteria mediated by various secondary metabolites (phycotoxins) have proven beneficial as it controls the algal bloom in the eutrophic water bodies. Herein, we attempt to review various opportunities and limitations of using a combination of microalgae and bacteria in wastewater treatment method toward cost effective, eco-friendly, and sustainable method of sewage treatment.
We determined the effect of acute and chronic toxicity of cadmium (Cd) on Pseudodiaptomus annandalei, according to their developmental and reproductive stages. Firstly, to estimate the 50% lethal ...concentration (LC50), acute exposure of nauplii and copepodids to 20, 40, 80, 150, and 300 μg/L of Cd was tested, and the effects of 5 μg/L and 40 μg/L of Cd on copepod developmental rate was done. Female lifespan and number of nauplii produced were compared. Secondly, one generation of copepod was exposed to dissolved (WCd) and dietary (DCd) Cd, and sex-specific Cd uptake and population density were estimated.
96 h LC50 was 40 μg/L Cd for nauplii and 120 μg/L Cd for copepodids. Duration of copepod development was 3.5 days and 5.5 days longer than the control when exposed to 5 μg/L and 40 μg/L of Cd, respectively. Female lifespan in both treatments were 9 and 8 days shorter than in the control, respectively. Total number of nauplii produced per female lifespan was 440 (control), 450 (5 μg/L Cd), and 365 (40 μg/L Cd). Cd uptake in copepods increased from nauplii to adults when exposed to dietary Cd and decreased when exposed to dissolved Cd. Dietary uptake of Cd was significantly higher in males than in females and Cd uptake from water was higher in males than in females, but not statistically significant. The total population of copepods were significantly affected by Cd. The toxic effects of Cd in copepods appear to depend on developmental stage, sex, duration and uptake route.
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•Toxic effects of cadmium in P. annandalei copepod was age-specific, with nauplii more sensitive than copepodids.•Cadmium toxicity delayed developmental rates, reduced naupliar production, and shortened the life span of females.•Cadmium uptake rate was higher from the water-borne route than from the dietary route.•Males bio-accumulated more cadmium than females.
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