Quantitative Proteomic Analysis Reveals the Key Molecular Events Driving Phaeocystis globosa Bloom and Dissipation.

Phaeocystis globosa is a marine-bloom-forming haptophyte with a polymorphic life cycle alternating between free-living cells and a colonial morphotype, that produces high biomass and impacts ecological structure and function. The mechanisms of P. globosa bloom formation have been extensively studied, and various environmental factors are believed to trigger these events. However, little is known about the intrinsic biological processes that drive the bloom process, and the mechanisms underlying P. globosa bloom formation remain enigmatic. Here, we investigated a P. globosa bloom occurring along the Chinese coast and compared the proteomes of in situ P. globosa colonies from bloom and dissipation phases using a tandem mass tag (TMT)-based quantitative proteomic approach. Among the 5540 proteins identified, 191 and 109 proteins displayed higher abundances in the bloom and dissipation phases, respectively. The levels of proteins involved in photosynthesis, pigment metabolism, nitrogen metabolism, and matrix substrate biosynthesis were distinctly different between these two phases. Ambient nitrate is a key trigger of P. globosa bloom formation, while the enhanced light harvest and multiple inorganic carbon-concentrating mechanisms support the prosperousness of colonies in the bloom phase. Additionally, colonies in the bloom phase have greater carbon fixation potential, with more carbon and energy being fixed and flowing toward the colonial matrix biosynthesis. Our study revealed the key biological processes underlying P. globosa blooms and provides new insights into the mechanisms behind bloom formation.

Coastal sediment heavy metal(loid) pollution under multifaceted anthropogenic stress: Insights based on geochemical baselines and source-related risks.

Contamination and risk assessments generally ignore the potential bias in results caused by the variation of background values at different spatial scales due to the spatial heterogeneity of sediments. This study aims to perform quantitative source-ecological risk assessment via establishing geochemical baselines values (GBVs) of heavy metal(loid)s (HMs) in Daya Bay, China. Cumulative frequency distribution (CFD) curves determined the GBVs of 12.44 (Cu), 30.88 (Pb), 69.89 (Zn), 0.06 (Cd), 47.85 (Cr), 6.80 (As), and 0.056 mg kg-1 (Hg), which were comparable to the background values of Guangdong Province surface soils, and implied a potential terrestrial origin of the coastal sediments. Principal component analysis (PCA) and positive matrix factorization (PMF) identified three sources (F1: natural processes; F2: anthropogenic impacts; F3: specific sources) with contributions of 51.7%, 29.2%, and 19.1%, respectively. The source-specific risk assessment revealed an ecological risk contribution potential of 73.8% for the mixed anthropogenic sources (F2 + F3) and only 26.2% for natural processes. Cd and Hg were the priority management of metallic elements, occupying 63.5% and 72.5% of the contribution weights of F2 and F3, respectively, which showed multi-level pollution potentials and ecological risk levels. The spatial distribution patterns demonstrated the hotspot features of HM pollution, and priority concerns should be given to the management of marine traffic and industrial point source pollution in Daya Bay. The results of the study provide a scientific approach and perspective for pollution treatment and risk management in the coastal environment.

Comparison of benthic nematode assemblages in native mangrove forest and exotic mangrove plantations (Sonneratia apetala Buch-Ham) along the South China Coast.

The exotic mangrove species Sonneratia apetala has been planted widely in China since 1985. As an exotic mangrove species, it is important to understand the influence of Sonneratia plantations on marine nematode assemblages. We studied the Zhanjiang and Xiatanwei mangrove wetlands on the South China Coast during the four seasons of 2010 and 2019. The results showed that S. apetala plantations increased the number of genera, Shannon-Wiener diversity, richness, evenness, maturity index (MI) and decreased the index of trophic diversity (ITD) values for nematodes compared to those in mudflats, but did not change significantly compared to those of native mangrove forests. In addition, Sonneratia plantations did not significantly change nematode assemblages compared to those of native mangroves, though they did change significantly compared to those in mudflats. Thus, interplanting S. apetala into native mangrove forests may be an effective substitute for using native mangroves in mangrove plantation.

How do spatial and environmental factors shape the structure of a coastal macrobenthic community and meroplanktonic larvae cohort? Evidence from Daya Bay.

We examined the relative importance of spatial processes (dispersal-related) and environmental processes (environmental selection-related) in community structure for macrobenthos (including juveniles and adults) and meroplanktonic larvae in the subtidal areas of Daya Bay, China. We found that both macrobenthos and meroplanktonic larvae showed similar spatial patterns, both following the distance-decay relationship. The results of variation partitioning analysis (VPA) showed the roles of both spatial and environmental factors in governing the assembly of both communities, although both explained only a small (slightly larger for spatial factor) fraction of the community variation. We also found that macrobenthos were more affected by spatial processes than meroplanktonic larvae. In addition, we highlight that the mechanisms determining community structure change according to the spatial extent considered.

Three new free-living marine nematode species of Dorylaimopsis (Nematoda: Araeolaimida: Comesomatidae) from the South China Sea and the Chukchi Sea.

Three new species of the free-living marine nematode genus Dorylaimopsis are described from the South China Sea and the Chukchi Sea. Dorylaimopsis longispicula sp. n. is characterized by cuticle with lateral differentiation consisting of four longitudinal rows of larger dots in pharyngeal and tail regions, two rows of larger dots elsewhere, long curved spicules, and 12-16 tubular precloacal supplements. Dorylaimopsis boucheri sp. n. is characterized by lateral differentiation consisting of 3-4 longitudinal rows of larger dots in males and 4-6 rows in females, beginning about 30 µm posterior to amphids and terminating at the conical portion of the tail, 13-16 tubular precloacal supplements, and distal part of tail cylindrical without terminal setae. Dorylaimopsis jinyuei sp. n. is characterized by cuticle with lateral differentiation in the form of longitudinal rows of larger dots in two separate regions, not along entire body. One region is from posterior edge of amphid to anterior of intestine or anterior border of pharyngeal bulb in some females (4-7 longitudinal rows), the other is the tail region (5-7 longitudinal rows). In this paper, Dorylaimopsis metatypica Chitwood, 1936 is transferred to Hopperia because it is characterized by lateral differentiation consisting of larger, irregularly-distributed coarse dots (as in Hopperia), and Hopperia communis Gagarin Nguyen, 2006 is transferred to Dorylaimopsis based on the presence of longitudinal rows of coarse dots and a cylindrical buccal cavity in most specimens of this species. A dichotomous key to valid species of Dorylaimopsis Ditlevsen, 1918 is provided.