Continuous warming drives the colonization dynamics of periphytic ciliate fauna in marine environments.

In order to evaluate the influence of global warming on the ecosystem processes in marine environments, the changes in colonization dynamics of periphytic microbiota were studied using the periphytic ciliate communities as the test organism fauna under a continuous warming gradient of 22℃ (control), 25℃, 28℃, 31℃, and 34 ℃. The results demonstrated that (1) the test ciliate communities generally showed a similar temporal pattern in within the colonization process under the water temperatures from 22 up to 28℃; however, (2) the colonization dynamics were significantly changed, and the fitness of colonization curves to the MacArthur-Wilson model equation was failed under the temperature increased by 6 ℃, and (3) the loading or assimilative capacity of the test aquatic ecosystem was decreased with the increase of water temperature. Therefore, this study suggests that continuous warming may significantly drive the colonization dynamics of periphytic ciliates in marine ecosystems.

An approach to evaluating seasonal responses to acute toxicity of antibiotic nitrofurazone on periphytic ciliated protist communities in marine environments.

Periphytic protists including ciliates are the primary components of microbial communities in which they play a vital role in the progression of food webs by moving resources from lower to higher trophic levels. However, the toxic effects of veterinary antibiotics on periphytic protists across four seasons are minimally understood. Therefore, in this study, a 1-year survey was conducted with the antibiotic nitrofurazone (NFZ) applied at concentrations of 0.0, 1.5, 3.0, 6.0, and 12.0 mg/L. Samples of protist communities were collected using microscope glass slides during four seasons in the coastal waters of the Yellow Sea, Qingdao, northern China. The abundance of protists dropped with an increase in NFZ concentrations, and almost all species were dead at a concentration of 12.0 mg/L. The 12 h-LC50 values of NFZ for the protist biota were similar among the four seasons, despite significant seasonal variability in the community structure. The present results suggest that the periphytic protist biota may be used as a biomarker for assessing the ecotoxicity of NFZ in marine environments regardless of the year season.

Microplastics drive community dynamics of periphytic protozoan fauna in marine environments.

The pollution of microplastics (MPs) to the marine environment has become a widespread focus of attention. To assess MP-induced ecotoxicity on marine ecosystems, periphytic protozoan communities were used as test organisms and exposed to five concentrations of MPs: 0, 1, 5, 25, and 125 mg l-1. Protozoan samples were collected using microscope slides from coastal waters of the Yellow Sea, northern China. A total of 13 protozoan species were identified and represented different tolerance to MP-induced ecotoxicity. Inhibition effects of MPs on the test protozoan communities were clearly shown in terms of both the species richness and individual abundance and followed linear relationships to MP concentrations. The community patterns were driven by MPs and significantly shifted at concentrations over 5 mg l-1. Our findings demonstrated that MPs may induce the community-level ecotoxic response of periphytic protozoan fauna and followed significant community dynamics. Thus, it is suggested that periphytic protozoan fauna may be used as useful community-based test model organisms for evaluating MP-induced ecotoxicity in marine environments.

Effects of continuous warming on homogeneity of periphytic protozoan fauna in marine ecosystems.

As a powerful biological indicator, multivariate dispersion in a community is widely used to evaluate the biological evaluation of environmental heterogeneity. To investigate the effects of persistent warming on microbial fauna in marine environments, the periphytic protozoan communities were used as test organisms and incubated in five temperature-controlled circulation system at 22 (control), 25, 28, 31 and 34 °C, respectively. The results showed that (1) there was a clear variation in species occurrence, and the α-/γ-diversity measures decreased with the increase of temperatures; (2) the compositional pattern was significantly driven by the persistent warming compared to community pattern from species-abundance data; and (3) both traditional ß-diversity and multivariate dispersion measures on species compositional matrix were significantly correlative with changes in the temperature. Therefore, it is suggested that continuous temperature fluctuations have a greater impact on homogeneity of species composition of protozoan communities than that of their community structure.

Continuous warming shifts the community pattern of periphytic protozoan fauna in marine environments.

Protozoan fauna is playing an important role in the functioning of microbial food webs by transferring the flux of material and energy from low to high tropic levels in marine ecosystems. To assess effects of elevated temperature on the marine ecosystem, periphytic protozoan communities were used as the test microbial fauna, and were incubated in a temperature-controlled circulation system in a successive temperature gradient of 22 (control), 25, 28, 31 and 34 °C. The results showed that: (1) the test microbial fauna was shifted in both species composition and community structure; (2) the average taxonomic distinctness represented a clear decreasing trend, (3) while the variation in taxonomic distinctness significantly increased with increase of water temperature; and (4) the community pattern was significantly departed from an expectation when temperature increased by 12 °C. These results suggested that Protozoa may be used as a useful bioindicator of global warming in marine ecosystems.

Can salinity variability drive the colonization dynamics of periphytic protozoan fauna in marine environments?

To investigate effects of salinity variability on colonization dynamics of periphytic protozoan fauna, a 21-day study was conducted in temperature-controlled circulation systems (TCCSs). Periphytic protozoan communities were incubated using glass slides as artificial substrata in five TCCS aquaria with a large-scale salinity gradient of 9, 19, 29 (control), 39, and 49 PSU, respectively. The colonization dynamics were observed on days 3, 5, 7, 10, 14, and 21. The colonization dynamics were well fitted to the MacArthur-Wilson and logistic model equations in colonization and growth curves in all five treatments, respectively. However, the maximum species richness and abundance were reduced, and the colonization patterns were significantly shifted in four treatments with salinity changed by 20 PSU compared to the control (29 PSU). Thus, it is suggested that the large-scale salinity variability may reduce the species richness significantly and affect colonization dynamics of periphytic protozoan fauna in marine environments.

Antibiotic nitrofurazone drives the functional dynamics of periphytic protozoan fauna in marine environments.

The use of functional traits of a community as a method to measure its functional dynamics in response to environmental change has gained attention because trait-based approaches offer systematic opportunities to understand the interactions between species diversity and ecosystem function. However, the relationship between functional traits of periphytic protozoa and contamination of aquatic habitats with antibiotics is poorly understood. In this study, we investigated the influence of the antibiotic nitrofurazone on functional traits of marine periphytic protozoan fauna. For this purpose, the protozoan assemblages were collected from coastal waters of the Yellow Sea at Qingdao, northern China, during four seasons of a one-year cycle using glass microscope slides as artificial substrates. The test protozoan communities were then exposed to various treatments of nitrofurazone in laboratory bioassay experiments. Our results demonstrated that the modalities of the functional traits of protozoan communities were generally driven by nitrofurazone toxicity. Briefly, R-mode linked to Q-mode (RLQ) and fourth-corner analyses revealed strong positive correlations between functional traits and nitrofurazone treatments. Trait syndromes in terms of body length, width, weight, height, and size to volume ratios were significantly influenced by nitrofurazone exposure. In particular, small and medium body size species of different feeding types, i.e., algivores, bacterivores, raptors or non-selectives, were more sensitive than other protozoan species to higher concentrations of nitrofurazone. Our findings demonstrate that antibiotic toxicity is likely to affect periphytic protozoan community function, shape the functional processes, and induce toxic responses in the community. The findings of this study suggest that periphytic protozoan communities and their functional traits are suitable bioindicators for evaluating the ecotoxicity of nitrofurazone in marine environments.

Colonization dynamics in body-size spectrum of protozoan periphytons for marine bioassessment using two modified sampling systems.

The body-size spectrum of microperiphytons has been proved to be a powerful tool for bioassessment. To explore colonization dynamics in body-size spectrum of periphytic protozoa in two modified sampling systems of both glass slide (mGS) and polyurethane foam unit (mPFU), a 28-day colonization survey was conducted in coastal waters of the Yellow Sea, China. A total of 7 body-size ranks were identified from 62 species, with 7 ranks (60 species) in the mGS and 6 ranks (37 species) in the mPFU system. The stable pattern with similar body-size spectra was found earlier in the mGS system than mPFU system during the colonization period. Both the trajectory and bootstrapped average analyses revealed that the colonization dynamics were significantly different in the body-size spectrum between the two methods. Based on our data, it suggests that the mGS system might be a better choice than the mPFU system for bioassessment in marine ecosystems.

Planktonic ciliate community driven by environmental variables and cyanobacterial blooms: A 9-year study in two subtropical reservoirs.

It is well-established that environmental variability and cyanobacterial blooms have major effects on the assembly and functioning of bacterial communities in both marine and freshwater habitats. It remains unclear, however, how the ciliate community responds to such changes over the long-term, particularly in subtropical lake and reservoir ecosystems. We analysed 9-year planktonic ciliate data series from the surface water of two subtropical reservoirs to elucidate the role of cyanobacterial bloom and environmental variabilities on the ciliate temporal dynamics. We identified five distinct periods of cyanobacterial succession in both reservoirs. Using multiple time-scale analyses, we found that the interannual variability of ciliate communities was more strongly related to cyanobacterial blooms than to other environmental variables or to seasonality. Moreover, the percentage of species turnover across cyanobacterial bloom and non-bloom periods increased significantly with time over the 9-year period. Phylogenetic analyses further indicated that 84 %-86 % of ciliate community turnover was governed by stochastic dispersal limitation or undominated processes, suggesting that the ciliate communities in subtropical reservoirs were mainly controlled by neutral processes. However, short-term blooms increased the selection pressure and drove 30 %-53 % of the ciliate community turnover. We found that the ciliate community composition was influenced by environmental conditions with nutrients, cyanobacterial biomass and microzooplankton having direct and/or indirect significant effects on the ciliate taxonomic or functional community dynamics. Our results provide new insights into the long-term temporal dynamics of planktonic ciliate communities under cyanobacterial bloom disturbance.

Can functional units of periphytic protozoan communities be used to evaluate the effects of harmful algal blooms on ecological quality in marine ecosystems?

Based on biological traits, the ecological quality status under the pressure of two harmful algal bloom (HAB) species was evaluated using functional units (FUs) of periphytic protozoan communities. Five treatments with different concentrations of Alexandrium tamarense and Gymnodinium catenatum, i.e., 100, 102, 103, 104, and 105 cells ml-1, were used. A total of 20 FUs were identified from 25 test protozoan species. Among these FUs, vagile algivores with large sizes showed a decreasing trend (i.e., in diversity and abundance) with increasing concentrations of algae, while vagile bacterivores and non-selectives with small sizes dominated at concentrations of 104 cells ml-1 of both algal species. Ellipse tests on pair-wise functional distinctness indices revealed a significant departure of test protozoan communities from an expected functional distinctness breadth when algal concentrations exceeded 104 cells ml-1. Based on these findings, it was concluded that FUs of periphytic protozoa may be a useful tool for evaluating the effects of HABs on ecological quality status in marine ecosystems.

Effects of nitrofurazone on ecosystem function in marine environments: A case study on microbial fauna.

To evaluate the effects of nitrofurazone on functional processes in marine ecosystems, periphytic protozoan communities were exposed to different concentrations of the antibiotic for a 10-day duration. Species trait distributions in the tested communities were observed during exposure to five concentrations of nitrofurazone. A fuzzy coding system with seven traits and seventeen categories was used to summarize the changes in functional patterns of the test organisms. Nitrofurazone had a significant influence on the function process of the periphytic ciliate communities. Bacterivores with flattened bodies were sensitive to the toxicant whereas sessile and cylindrical raptors showed a high tolerance to nitrofurazone, invariably dominating communities exposed to high concentrations. Bootstrapped-average analysis demonstrated a significant change in functional patterns at highest nitrofurazone concentrations (8 mg l-1). Based on these findings, it is suggested that nitrofurazone may negatively influence ecosystem function in marine environments.

Use of protozoan periphytons for evaluating of environmental heterogeneity in intertidal zones of marine ecosystems.

As an important biological indicator, multivariate dispersion in homogeneity of an observed community is a useful parameter for bioassessment of environmental heterogeneity. To identify the influence of tidal events on homogeneity of protozoan periphyton fauna from the highest tideline to the lowest, a 1-month baseline survey was carried out along five tidelines (sites A-E) in an intertidal zone of the Yellow Sea, northern China. There was a significant influence of tidal events on the homogeneity in both compositional and community structure among five tidelines. The ß-diversity measures generally decreased from the highest tideline to the lowest. The biodiversity indices of the protozoans dropped sharply from the highest to the middle tidelines, followed by an increase until to the lowest tideline. These findings suggest that the homogeneity of protozoan periphyton in both species composition and relative abundance was significantly shaped by the environmental heterogeneity in intertidal zones of marine ecosystems.

Insights for monitoring surveys into influence of tidal events on protozoan periphyton fauna along the tidelines of Yellow Sea, Northern China.

To explore the influence of tidal events on protozoan periphyton fauna along tidelines, a 1-month baseline survey for bioassessment was conducted in an intertidal zone of the Yellow Sea, Northern China. A total of 27 protozoans species were identified among five sampling sites along five tidelines (sites A-E). The periphytic protozoans showed a significant variation in species distribution and community pattern along five tidelines. Species richness decreased from the high tideline (site A) and reached the minimum value at the middle tideline (site C), followed by an increase up to the low tideline (site E). Individual abundances peaked at site C and leveled off at the other four tidelines. Species richness, evenness, and diversity showed low value at site C compared with those at the other four sites. These findings suggest that periphytic protozoan fauna was shaped by tidal events along the tidelines of marine ecosystems.

An approach to determining the nitrofurazone-induced toxic dynamics for ecotoxicity assessment using protozoan periphytons in marine ecosystems.

With several observable responses and sensitivity of protozoans to nitrofurazone (NFZ), the toxic effects of NFZ on protozoans can be an early warning signal of NFZ contamination in the aquatic environment. To evaluate the toxic dynamics induced by NFZ, protozoan samples were collected using microscopy glass slides and exposed to the five concentrations of NFZ: 0, 1, 2, 4, and 8 mg ml-1. Substantial differences in the species composition and toxic-dynamics patterns were observed among all concentrations. Briefly, periphytic euplotids and pleurostomatids were the most prevalent at each concentration level, while dysteriids were less dominant among all treatments. Multivariate analysis revealed significant (P < 0.05) differences in the taxonomic patterns of the test organisms among the five treatments. Furthermore, significant deviation of protozoan communities from the expected taxonomic breadth was observed to occur in a dose-dependent manner. Based on these findings, it is suggested that protozoan periphytons could be used as bioindicators to assess the ecotoxicity of NFZ in the marine environment.

How do microalgae in response to biological pollution treat in cultivation? A case study investigating microalgal defense against ciliate predator Euplotes vannus.

Microalgae have significant amounts of proteins, lipids, carotenoids, vitamins, minerals, and unique pigments. However, with the gradual expansion of microalgae cultivation, hostile biological pollution seriously restricted the large-scale microalgae cultivation and limited the exploitation of its biological resources. Moreover, protozoan poses the greatest threat to microalgae cultivation. Here, the relationship between six marine economic microalgae populations and their ciliate predator Euplotes vannus was examined. And four concentrations were designed for each type of microalgae to carry out the experiment. It was revealed that four species of microalgae inhibit the ciliate population growth at high density. Furthermore, the experiment which was the influence of microalgae at three different growth stages on the growth of the ciliates for these four kinds of high-density inhibitory microalgae was designed. The microalgae inhibitory effects were already exhibited at the end of the exponential growth phase, and it was significantly inhibited during the stationary growth phase. As the microalgae concentration increased, the inhibitory effect became more pronounced. This study provides fundamental data for screening protozoan-inhibiting microalgae and shows potential to be used in algae cultivation.

Can tidal events influence analysis on colonization dynamics in body-size spectrum of periphytic ciliates for marine bioassessment?

The tidal influence on body-size spectrum of the protozoan periphytons was explored by using the conventional slide system (CS) and the polyurethane foam enveloped slide system (PFES) in coastal waters during a 1-month study. During the colonization process, clear temporal patterns of the body-size spectrum were observed using the two sampling methods. In terms of relative species number and frequency of occurrence, the rank S4 represented a more stable temporal variability in the PFES system than the CS system during the colonization. Additionally, the small forms (e.g., S1, S2, and S3) were more abundant in the PFES system. The clustering and bootstrapped average analyses demonstrated differences in body-size spectrum of protozoans between the two sampling systems. Our results imply that the body-size spectrum of protozoan periphytons may be impacted by tidal events during colonization process in marine waters.