Detecting Regime Shifts in the Portuguese Continental Shelf Ecosystem Within the Last Three Decades

Marine ecosystems are affected by diverse pressures and consequently may undergo significant changes that can be interpreted as regime shifts. In this study we used integrated trend analysis (ITA) that combines multivariate statistics and methodologies to identify abrupt changes in time-series, in order to test a hypothesis about the occurrence of regime shifts in the Portuguese continental shelf ecosystem (PCSE). We used two types of data describing ecosystem drivers (fishing mortality and environmental/climatic indices) and ecosystem state (observed and modelled biomass and ecosystem indices). Modelled biomass and ecosystem indices were outputs of Ecopath with Ecosim temporal model parametrised for PSCE between 1986 and 2017. The analyses indicated that the regime shifts in the PCSE have occurred during three periods in the last three decades: “early regime” until the mid-1990s, followed by “transition regime” in-between and “late regime” since the mid-2010s. The detected regime shifts are characterised by changes in the pelagic community that became more dominant when compared to the demersal community and shifted from sardine, the main fishing resource, abundant in the “early regime”, to other less valuable pelagic fishes such as chub mackerel that dominated the “late regime”. The “early regime” was characterised by high catch, a larger proportion of demersal species, and higher diversity while, the “late regime” was represented by lower catch, an increase in higher trophic level (TL) predatory fish and lower diversity. Moreover, the “late regime” showed lower resilience and reduced maturity when compared to the “early regime”. Changes described in the ecosystem were probably related to (1) the shift in the north Atlantic environmental conditions that affected small pelagic fish (SPF) and lower TLs groups, (2) reduction in fishing pressure, and (3) internal triggers, related to the indirect trophic interactions that might have benefited higher TL fish and impacted the pelagic community. In the context of PCSE management, this study highlighted a need to consider the possibility of regime shifts in the management process. For example, regime specific harvest rates and environmental reference points should be considered when an indication of abrupt change in the ecosystem exists.

Identification of opportunistic and nonopportunistic Exophiala species using high resolution melting analysis

Exophiala is a genus comprising several species of opportunistic black yeasts. Exophiala species identification by morphological, physiological, and biochemical characteristics is challenging because of the low degree of phenotypic differences between species and its polyphyletic nature. We aimed to develop a high-resolution melting (HRM) assay based on the internal transcribed spacer (ITS) region to differentiate between pairs of clinical and environmental Exophiala species. HRM primers were designed based on the conserved ITS region of five Exophiala species (E. dermatitidis, E. phaeomuriformis, E. heteromorpha, E. xenobiotica, and E. crusticola). Environmental and clinical Exophiala isolates representing these five species (n = 109) were analyzed. The HRM assay was optimized using clinical and environmental reference isolates (n = 22), and then the results were compared with those obtained with nonreference isolates of Exophiala (n = 87) using two designed primer sets. The designed HRM assay was based on the normalized melting peak approach and two primer sets, and successfully distinguished between the five Exophiala species. The HRM1 primer set provided sufficient resolution, with a melting temperature (Tm) difference of approximately 2.5°C among the analyzed species and of approximately 1°C between E. dermatitidis and E. phaeomuriformis. HRM typing results were in agreement with those of ITS-sequence typing (100% sensitivity and specificity). The developed HRM assay can be used to ascertain the identity of Exophiala species, which may differ in clinical significance, with high accuracy. Its application to identify species directly in clinical samples and/or environmental niches may be possible in the future.

Clean Power Dispatching of Coal-Fired Power Generation in China Based on the Production Cleanliness Evaluation Method

China’s achievements in climate change and clean energy have been recognized by the international community. Although China has achieved successes in the field of clean energy, especially clean power dispatch, power dispatch is still one-sided and incomplete when considering environmental aspects. This paper presents a comprehensive production cleanliness evaluation model to assign a comprehensive environmental value as a reference for clean power dispatch. The model considers all the pollutants currently regulated in China’s coal-fired power plants, carbon emissions, and sustainability as three basic environmental constraints. Then, emergy analysis is used to unify the input/output materials with different units of measurement, and the emergy-based environmental value added (EEVA) value is constructed. As an integrated environmental value, the EEVA can provide an environmental reference for clean power dispatch. Finally, we selected a representative coal-fired power plant in China as a case study. By applying the above model, the dispatching sequence for four generating units was arranged from the perspective of cleanliness.

Seasonal Dynamics of Algae-Infecting Viruses and Their Inferred Interactions with Protists

Viruses are a highly abundant, dynamic, and diverse component of planktonic communities that have key roles in marine ecosystems. We aimed to reveal the diversity and dynamics of marine large dsDNA viruses infecting algae in the Northern Skagerrak, South Norway through the year by metabarcoding, targeting the major capsid protein (MCP) and its correlation to protist diversity and dynamics. Metabarcoding results demonstrated a high diversity of algal viruses compared to previous metabarcoding surveys in Norwegian coastal waters. We obtained 313 putative algal virus operational taxonomic units (vOTUs), all classified by phylogenetic analyses to either the Phycodnaviridae or Mimiviridae families, most of them in clades without any cultured or environmental reference sequences. The viral community showed a clear temporal variation, with some vOTUs persisting for several months. The results indicate co-occurrences between abundant viruses and potential hosts during long periods. This study gives new insights into the virus-algal host dynamics and provides a baseline for future studies of algal virus diversity and temporal dynamics.