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The Jehol and Yanliao biotas of northern China, two world‐class Lagerstätten with abundant biomass and biodiversity, provide critical clues to Mesozoic terrestrial ecosystems. Their evolution is a response to the destruction of the North China craton. However, the impetus for the rapid bloom of the biotas remains a mystery. Mesozoic large‐scale volcanic‐sedimentary strata in northern China are rich in terrestrial organisms. Statistical analyses show that volcanic nutrient element delivery, biomass, and biodiversity in these stratigraphic sequences increase synchronously, while harmful elements have the opposite change with them. These observations reveal the coevolutionary relationship between volcanism and terrestrial biotas. The increased nutrient element supply and inhibited harmful element delivery to terrestrial ecosystems from the voluminous volcanic products, produced under the geodynamic regime of paleo‐Pacific subduction and cratonic destruction, could create a conducive environment for the biodiversity and high prosperity of Mesozoic terrestrial biotas. Plain Language Summary: The weathering of volcanic products can quickly provide material supply for ecosystems, including nutrient and harmful elements. The availability of these elements in volcanic‐sedimentary sequences can provide key evidence for the intrinsic relations between volcanism and terrestrial biological evolution. Through statistically‐based big data analyses, we determine the changes in nutrient/harmful element delivery, biomass, and vertebrate and entomic diversity of the Mesozoic fossil‐bearing volcanic‐sedimentary strata in northern China. Excluding the interference of pyroclastic flows on the fossil records, the results reveal the significant contributions of elevated volcanic nutrient supply to the flourishing of the Jehol and Yanliao biotas. Meanwhile, the inhibited release of harmful elements has limited impacts on the biotas. This study opens a new path for multidisciplinary investigations to explore the feedback relationship among regional tectonics, volcanism, and terrestrial biotas. Key Points: Mesozoic terrestrial biotas in northern China coevolved with volcanism during the paleo‐Pacific subduction and cratonic destructionThe increasing supply of volcanic nutrients promoted the flourishing of the Jehol and Yanliao biotasInhibited volcanic toxic delivery facilitated the rapid bloom of the terrestrial biotas [ABSTRACT FROM AUTHOR]

Abstract The Jehol and Yanliao biotas of northern China, two world‐class Lagerstätten with abundant biomass and biodiversity, provide critical clues to Mesozoic terrestrial ecosystems. Their evolution is a response to the destruction of the North China craton. However, the impetus for the rapid bloom of the biotas remains a mystery. Mesozoic large‐scale volcanic‐sedimentary strata in northern China are rich in terrestrial organisms. Statistical analyses show that volcanic nutrient element delivery, biomass, and biodiversity in these stratigraphic sequences increase synchronously, while harmful elements have the opposite change with them. These observations reveal the coevolutionary relationship between volcanism and terrestrial biotas. The increased nutrient element supply and inhibited harmful element delivery to terrestrial ecosystems from the voluminous volcanic products, produced under the geodynamic regime of paleo‐Pacific subduction and cratonic destruction, could create a conducive environment for the biodiversity and high prosperity of Mesozoic terrestrial biotas.

In the subtropical gyres, phytoplankton rely on eddies for transporting nutrients from depth to the euphotic zone. But, what controls the rate of nutrient supply for new production? We show that vertical nutrient flux both depends on the vertical motion within the eddying flow and varies nonlinearly with the phytoplankton growth rate. Flux is maximized when the growth rate matches the inverse of the decorrelation timescale for vertical motion. Using a three‐dimensional ocean model and a linear nutrient uptake model, we find that phytoplankton productivity is maximized for a growth rate of 1/3 day−1, which corresponds to the timescale of submesoscale dynamics. Variability in the frequency of vertical motion across different physical features of the flow favors phytoplankton production with different growth rates. Such a growth‐transport feedback can generate diversity in the phytoplankton community structure at submesoscales and higher net productivity in the presence of community diversity. Plain Language Summary: The productivity of phytoplankton is the result of a two‐way coupling between the rate of phytoplankton growth and nutrient supply by physical mechanisms. A three‐dimensional model of an oceanic eddy flow field maximizes its nutrient flux to the sunlit surface layer when the average phytoplankton growth rate is approximately 1/3 day−1, which is consistent with observations. Different features of the flow field experience variable frequencies in the up/down motion and favor different phytoplankton growth rates to maximize new production, providing a way to generate diversity in the community composition of phytoplankton. Since changing the grid resolution of ocean models alters the vertical velocities, the biological growth rates also ought to be altered to represent the appropriate physical‐biological coupling. Key Points: Nutrient flux depends nonlinearly on the rate of biological nutrient uptake with a maximum at a particular rateIn a subtropical eddy field, the nutrient uptake rate that maximizes nutrient flux corresponds to the frequency of submesoscale dynamicsVariability in vertical velocity characteristics on water mass trajectories could favor phytoplankton with a diversity of growth rates [ABSTRACT FROM AUTHOR]

In oligotrophic gyres of the tropical ocean, islands can enhance phytoplankton biomass and create hotspots of productivity and biodiversity. This "island mass effect" (IME) is typically identified by increased chlorophyll concentrations next to an island. Here we use a simple plankton model in a Lagrangian framework to represent an unexplained open ocean bloom, demonstrating how islands could have triggered it remotely. This new type of IME, termed "delayed IME," occurs when nitrate is limiting, N:P ratios are low, and excess phosphate and iron remain in water masses after an initial bloom associated with a "classical" IME. Nitrogen fixers then slowly utilize leftover phosphate and iron while water masses get advected away, resulting in a bloom decoupled in time (several weeks) and space (hundreds of kilometers) from island‐driven nutrient supply. This study suggests that the fertilizing effect of islands on phytoplankton may have been largely underestimated. Plain Language Summary: In the poor and nutrient‐depleted waters of the tropical Pacific, islands act as sources of nutrients fertilizing nearby waters. These nutrients are consumed by microscopic photosynthesizing algae, the phytoplankton. The resulting phytoplankton enrichments (blooms) in turn support productive ecosystems. This phenomenon, termed the "island mass effect," has been known for 60 years and is classically defined by increased chlorophyll (representing phytoplankton biomass) next to an island. Blooms also occur in the open ocean and are usually attributed to vertical processes such as mixing or uplifting that locally supply nutrients from subsurface reservoirs. In this paper, we demonstrate that a different type of island mass effect exists, where the phytoplankton response is delayed because they grow very slowly. These blooms are supported by the nitrogen fixer Trichodesmium. Since phytoplankton get carried away from islands by oceanic currents while they grow, this can lead to a bloom located hundreds of kilometers away with no apparent connection to the islands. Nutrient inputs by islands followed by advection can thus trigger remote blooms in the open ocean. Our study suggests that the fertilizing effect of islands may currently be largely underestimated, particularly in the warm waters of the tropical Pacific where Trichodesmimum is common. Key Points: Previously undescribed delayed island mass effects can generate intense blooms decoupled from island fertilization both in time and in spaceThese occur when diazotrophs slowly utilize excess phosphate and iron after a classical island effect while being advected away from islandsThe fertilizing impact of islands on phytoplankton may thus currently be largely underestimated in the oligotrophic ocean [ABSTRACT FROM AUTHOR]