Use of biological trait analysis of periphytic protozoan assemblages for evaluating effects of harmful algal blooms on ecological quality status in marine ecosystem

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.

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.

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.

Identifying Spatial Priority of Ecological Restoration Dependent on Landscape Quality Trends in Metropolitan Areas

Ecological restoration has become an important tool for mitigating and adapting to environmental degradation caused by global urbanization. However, current research has focused on single indicators and qualitative analysis, meaning that ecological restoration has not been effectively and comprehensively addressed. This study constructed a spatial priority identification system for ecological restoration, with landscape area, landscape structure and landscape function as the core indicators. The system has wide adaptability. In this work, the spatial classification of ecological degradation was performed by overlay analysis. The results showed the following: (1) In the Shanghai metropolitan area, the landscape quality showed a trend of degradation, with built-up areas encroaching on forests and cropland. (2) Ecological degradation in the suburbs was more severe than that in the urban center. Forests had the highest landscape area indicator (LAI) stability. Significant degradation of landscape structure indicators (LSIs) occurred when built-up area and cropland were transformed into forests. (3) Different types of ecological restoration had significant spatial distribution patterns. Through this identification system, this study aimed to help planners/managers of ecological restoration to recognize the changing patterns of regional landscape quality and its relationship with land cover. It ultimately provides a basis for the formulation of regional ecological objectives and spatial strategies.

An approach to evaluating the acute toxicity of nitrofurazone on community functioning using protozoan periphytons

The acute toxicity of nitrofurazone on community functioning was studied using an acute toxicity test. Consequently, 14-day protozoan periphyton assemblages were used as test organism communities, under a range of nitrofurazone concentrations including 0 (control), 0.5, 3, 6, and 12 mg ml^-1 within 0, 2, 4, 6, 8, 10, and 12 h time duration. Fuzzy coding system of functional traits classified the test protozoan periphyton community into six major traits and 15 categories. Briefly, community-weighted means (CWM) were used to identify the community functioning of test protozoan assemblage. Inferences demonstrate a drastic/significant variation in the functional patterns of the test organisms at a high concentration (12 mg ml^-1) after an exposure time of 12 h, but the functional diversity indices leveled off at the exposure time of 10 h and then dropped sharply. These results suggested that nitrofurazone may significantly influence the community functioning in marine ecosystems.