Natural Variability in Caribbean Coral Physiology and Implications for Coral Bleaching Resilience

Coral reefs are among the most diverse and complex ecosystems in the world that provide important ecological and economical services. Increases in sea surface temperature linked to global climate change threatens these ecosystems by inducing coral bleaching. However, it is not fully known if natural intra- or inter-annual physiological variability is linked to bleaching resilience or recovery capacity of corals. Here, we monitored the coral physiology of three common Caribbean species (Porites divaricata, Porites astreoides, Orbicella faveolata) at six time points over 2 years by measuring the following traits: calcification, biomass, lipids, proteins, carbohydrates, chlorophyll a, algal endosymbiont density, stable carbon isotopes of the host and endosymbiotic algae, and the stable carbon and oxygen isotopes of the skeleton. The overall physiological profile of all three species varied over time and that of P. divaricata was consistently different from the two other coral species. Porites divaricata had higher energy reserves coupled with higher contributions of heterotrophically derived carbon to host tissues than both P. astreoides and O. faveolata. Consistently higher overall energy reserves and heterotrophic contributions to tissues appear to buffer against environmental stress, including bleaching events. Thus, natural physiological variability among coral species appears to be a stronger predictor of coral bleaching resilience than intra- or inter-annual physiological variability within a coral species.

Battery Energy Storage Participation in Automatic Generation Control of Island Systems, Coordinated with State of Charge Regulation

Efficient storage participation in the secondary frequency regulation of island systems is a prerequisite towards their complete decarbonization. However, energy reserve limitations of storage resources pose challenges to their integration in centralized automatic generation control (AGC). This paper presents a frequency control method, in which battery energy storage systems (BESSs) participate in automatic frequency restoration reserve (aFRR) provision, through their integration in the AGC of an island system. A local state of charge (SOC) controller ensures safe operation of the BESS in case of disturbances, without jeopardizing system security when available energy reserves are diminishing. The aFRR participation factors of regulating units are altered when the storage systems approach their SOC limits, re-allocating their reserves to other load-following units. Restoration of BESS energy reserves is achieved by integrating SOC regulation in the real-time economic dispatch of the system, formulated as a mixed-integer linear programming problem and solved every few minutes to determine the base points of the AGC units. A small autonomous power system, comprising conventional units, renewable energy sources and a BESS, is used as a study case to evaluate the performance of the proposed method, which is compared with alternative approaches to secondary regulation with BESS participation.

Estimation Method of Biomass Energy Reserves in China: A Case Study of Corn Straw

Nowadays, biomass resources are the best choice to replace fossil resources. Energy development in biomass is mainly through pyrolysis of biomass. At present, no one has estimated how much biomass energy there is for a country. In this article, taking corn as an example, China as the production country, the potential biomass resources in China are speculated, in which Lignocellulose is the main experimental biomass and pyrolyzed to obtain biomass energy. The most common method of biomass energy conversion is isothermal conversion. The first-order reaction model is used for kinetic analysis of the conversion. The sample is subjected to powder falling pyrolysis at 480 degrees. In order to overcome the regional differences in China, the data of 30 degrees north latitude are used. Finally, the reaction time and the total amount of biomass energy available for development and utilization in China in 2020 are obtained.

The algae revolution 2.0: the potential of algae for the production of food, feed, fuel and bioproducts – why we need it now

Algae made our world possible, and it can help us make the future more sustainable; but we need to change the way we live and adopt new more efficient production systems, and we need to do that now. When the world was new, the atmosphere was mainly carbon dioxide, and no animal life was possible. Along came algae with the process of photosynthesis, and things began to change. Ancient cyanobacteria algae turned carbon dioxide into enormous sums of lipids, proteins and carbohydrates, while they secreted oxygen into the atmosphere. Over a billion years, as oxygen filled the air and algae filled the seas, animal life became possible. Eventually all that algae biomass became petroleum and natural gas, which for eons sat undisturbed in vast underground reservoirs, holding enormous sums of untapped energy. Less than 200 years ago humans learned to tap these energy reserves to create the world we know today, but in so doing, we have released millions of years of stored CO2 back into the atmosphere. Algae can again help make the world a better place, but this will require new thinking and new ways of producing our food, feed and fuels. We need an algae revolution 2.0.

Energetic and reproductive costs of coral recovery in divergent bleaching responses

Mass thermal bleaching events are a primary threat to coral reefs, yet the sublethal impacts, particularly on energetics and reproduction, are poorly characterized. Given that the persistence of coral populations is contingent upon the reproduction of individuals that survive disturbances, there is an urgent need to understand the sublethal effects of bleaching on reproductive output to accurately predict coral recovery rates. In 2019, the French Polynesian island of Mo’orea experienced a severe mass bleaching event accompanied by widespread coral mortality. At the most heavily impacted sites, we observed Acropora hyacinthus individuals that were resistant to bleaching, alongside colonies that bleached but showed signs of symbiont recovery shortly after the bleaching event. We collected fragments from A. hyacinthus colonies five months post-bleaching and, using energetic assays and histological measurements, examined the physiological and reproductive consequences of these two distinct heat stress responses. Despite healthy appearances in both resistant and recovered corals, we found that recovered colonies had significantly reduced energy reserves compared to resistant colonies. In addition, we detected compound effects of stress on reproduction: recovered colonies displayed both a lower probability of containing gametes and lower fecundity per polyp. Our results indicate that bleaching inflicts an energetic constraint on the concurrent re-accumulation of energy reserves and development of reproductive material, with decreased reproductive potential of survivors possibly hampering overall reef resilience. These findings highlight the presence of intraspecific responses to bleaching and the importance of considering multiple trajectories for individual species when predicting population recovery following disturbance.

Black Sea turbot sperm motility depending on the dilution of seawater

The sperm motility of fish reflects their fertilizing ability. Sperm activation in fish with external fertilization occurs in an isotonic medium (sea or freshwater). The duration of sperm motility is a compromise between the level of energy reserves possessed by the sperm and the process of osmotic damage it experiences in the activating medium. Under natural conditions, various biotic and abiotic factors can affect the characteristics of motility. At the same time, when assessing the reproductive potential of males in laboratory conditions, the dilution and methods of its activation have a significant effect on the characteristics of sperm quality (namely, speed, the proportion of motile spermatozoa, and the time of their activity). In our work, we determined the main characteristics of the motility of the Black Sea turbot sperm at a dilution of 1:10 and 1: 100 with seawater. We have shown that, the average speed and percentage of motile sperm significantly decrease with higher dilution of seawater.