Evenness, biodiversity, and ecosystem function of intertidal communities along the Italian coasts: Experimental short-term response to ambient and extreme air temperatures

Signals of loss, part two: A phytal community collapsing under extreme-climate conditions on a Mediterranean vermetid reef

Climate change is increasing the frequency and intensity of transient extreme climate events that can be catastrophic for ecological communities. We studied the 2014-2022 period along the northern coasts of Sicily (Western Mediterranean Sea), evaluating the ecological impacts on three macroalgae (Ericaria amentacea, Jania rubens, and Padina pavonica) and one complex of species (Laurencia complex) inhabiting the vermetid bioconstructions. All climatological metrics indicate that desiccation conditions occurred in the intertidal zones for many consecutive days during 2022, compared to previous years. These extreme conditions have led to a drastic algal biomass reduction, especially for E. amentacea, P. pavonica, and Laurencia complex species. Consistently, the analysis of mollusc communities associated with macroalgae highlighted a sharp collapse, with a general inverse relationship between community composition and structure versus air temperature values. This worrying evidence indicates that anomalous desiccation conditions could have serious short-term impacts on the fragile and neglected vermetid ecosystem.

Understanding the intricate tradeoffs among ecosystem services in the Beijing-Tianjin-Hebei urban agglomeration across spatiotemporal features

Revealing the intricate interactions between ecosystem services and their values is essential for the comprehensive management of diverse ecosystems. However, understanding tradeoffs among various ecosystem services and their influencing factors, especially at different spatial scales, remains challenging, primarily due to the difficulty in quantifying cultural services. In this study, we conducted a comprehensive analysis of the ecosystem service value (ESV) at both grid and county scales in the Beijing-Tianjin-Hebei urban agglomeration from 2000 to 2020, considering the representation of different ecosystem services. Our investigation aimed to elucidate tradeoffs among ecosystem services and identify key natural-social-economic-climate drivers. The key findings are as follows: (1) Over the study period, the overall ESV in the Beijing-Tianjin-Hebei urban agglomeration exhibited an upward trend, with regulation of waterflows, water body, and forest land making the largest contributions. (2) At the grid scale, there were 3 tradeoffs and 52 synergies among multiple ecosystem services in 2000, which increased to 18 tradeoffs in 2020, indicating a considerable degradation of numerous ecosystem services. Conversely, at the county scale, all ecosystem services exhibited a synergistic relationship. (3) The most significant synergistic effect was observed between regulation of waterflows and maintenance of soil fertility, while the most prominent tradeoff effect was identified between food production and waste treatment. (4) Social-economic factors exerted a more substantial influence on ESV, followed by climate factors, whereas the impact of natural factors was limited. GDP emerged as the primary single driver of total ESV, while farmland production potential played a crucial role in shaping the 11 ecosystem services. Notably, GDP-temperature and GDP-farmland production potential output were identified as the most influential dual factors. These findings underscore the importance of simultaneously enhancing economic development, controlling temperature rise, and improving food production as essential measures to enhance ESV.

Warming and nutrient enrichment can trigger seaweed loss by dysregulation of the microbiome structure and predicted function

Warming and nutrient enrichment are key pervasive drivers of ecological shifts in both aquatic and terrestrial ecosystems, impairing the physiology and survival of a wide range of foundation species. But the underlying mechanisms often remain unclear, and experiments have overlooked the potential effects mediated by changes in the microbial communities. We experimentally tested in the field orthogonal stress combinations from simulated air warming and nutrient enrichment on the intertidal foundation seaweed Cystoseira compressa, and its associated bacterial communities. A total of 523 Amplicon Sequence Variance (ASVs) formed the bacterial community on C. compressa, with 222 ASVs assigned to 69 taxa at the genus level. Most bacteria taxa experienced changes in abundance as a result of additive (65 %) and antagonistic (30 %) interactions between the two stressors, with synergies (5 %) occurring less frequently. The analysis of the predicted bacterial functional profile identified 160 metabolic pathways, and showed that these were mostly affected by additive interactions (74 %) between air warming and nutrient enrichment, while antagonisms (20 %) and synergisms (6 %) were less frequent. Overall, the two stressors combined increased functions associated with seaweed disease or degradation of major cell-wall polymers and other algicidal processes, and decreased functions associated with Quorum Quenching and photosynthetic response. We conclude that warming and nutrient enrichment can dysregulate the microbiome of seaweeds, providing a plausible mechanism for their ongoing loss, and encourage more research into the effects of human impacts on crucial but yet largely unstudied host-microbiome relationships in different aquatic and terrestrial species.