• Energy Research

In the biodiverse Nakdong River estuary, the predominant seagrass and salt marsh species, Zostera japonica and Bolboschoenus planiculmis, are declining due to human and natural pressures. Our study investigated how environmental factors and co-existing salt marsh vegetation impact the growth and reproduction of Z. japonica. Understanding the reproductive dynamics of Z. japonica in this estuary is crucial, as sexual reproduction ensures the resilience and stability of seagrass populations in challenging environments. This study revealed that approximately 49% of Z. japonica shoots flowered, yet none persisted to the subsequent growth season, indicating a reliance on sexual reproduction for population resilience. The presence of competing B. planiculmis shoots and Ulva pertusa indirectly suppressed the growth and reproduction of Z. japonica by reducing light availability. Additionally, environmental stresses that occurred during summer, such as elevated temperatures, reduced salinity, and sediment transport, likely affected the vegetative and reproductive performance of Z. japonica in this estuary. Consequently, Z. japonica in this estuary has adopted a mixed annual life history strategy in response to these environmental oscillations. Our findings highlight the vulnerability of the Z. japonica population to seasonal environmental shifts and interspecies competition in this estuary, offering essential considerations for its conservation and effective management.

In the biodiverse Nakdong River estuary, the predominant seagrass and salt marsh species, Zostera japonica and Bolboschoenus planiculmis, are declining due to human and natural pressures. Our study investigated how environmental factors and co-existing salt marsh vegetation impact the growth and reproduction of Z. japonica. Understanding the reproductive dynamics of Z. japonica in this estuary is crucial, as sexual reproduction ensures the resilience and stability of seagrass populations in challenging environments. This study revealed that approximately 49% of Z. japonica shoots flowered, yet none persisted to the subsequent growth season, indicating a reliance on sexual reproduction for population resilience. The presence of competing B. planiculmis shoots and Ulva pertusa indirectly suppressed the growth and reproduction of Z. japonica by reducing light availability. Additionally, environmental stresses that occurred during summer, such as elevated temperatures, reduced salinity, and sediment transport, likely affected the vegetative and reproductive performance of Z. japonica in this estuary. Consequently, Z. japonica in this estuary has adopted a mixed annual life history strategy in response to these environmental oscillations. Our findings highlight the vulnerability of the Z. japonica population to seasonal environmental shifts and interspecies competition in this estuary, offering essential considerations for its conservation and effective management.

The seagrass ecosystem is among the most efficient natural carbon sinks that can contribute to climate change mitigation. However, little is known about the effects of coastal nutrient enrichment caused by anthropogenic activities and/or climate change on the capacity of the seagrass blue carbon sink. Our experimental manipulations of sediment nutrient enrichment shifted the blue carbon sink capabilities of seagrass meadows. Sediment nutrient enrichment significantly increased the nutrient content of seagrass litter, stimulating the decomposition of rhizome + root litter by ∼10% while retarding the decomposition of leaf litter by ∼5%. Sediment N + P enrichment increased seagrass growth and litter production, while enrichment of N or P alone did not. Organic carbon (Corg) stocks in the surface sediments (0-5 cm) were 34% higher than those in the control with N + P enrichment due to high litter production and the low decomposition rate of nutrient-enriched leaf litter. However, Corg stocks in the subsurface sediments (5-20 cm) did not increase with sediment nutrient enrichment, which is likely due to accelerated decomposition of rhizome + root litter. Our findings suggest that nutrient loading in coastal sediments alters the blue carbon sink and storage capacities in seagrass meadows by changing the rates of carbon sequestration and decomposition.

The seagrass ecosystem is among the most efficient natural carbon sinks that can contribute to climate change mitigation. However, little is known about the effects of coastal nutrient enrichment caused by anthropogenic activities and/or climate change on the capacity of the seagrass blue carbon sink. Our experimental manipulations of sediment nutrient enrichment shifted the blue carbon sink capabilities of seagrass meadows. Sediment nutrient enrichment significantly increased the nutrient content of seagrass litter, stimulating the decomposition of rhizome + root litter by ∼10% while retarding the decomposition of leaf litter by ∼5%. Sediment N + P enrichment increased seagrass growth and litter production, while enrichment of N or P alone did not. Organic carbon (Corg) stocks in the surface sediments (0-5 cm) were 34% higher than those in the control with N + P enrichment due to high litter production and the low decomposition rate of nutrient-enriched leaf litter. However, Corg stocks in the subsurface sediments (5-20 cm) did not increase with sediment nutrient enrichment, which is likely due to accelerated decomposition of rhizome + root litter. Our findings suggest that nutrient loading in coastal sediments alters the blue carbon sink and storage capacities in seagrass meadows by changing the rates of carbon sequestration and decomposition.

Distribution of Earth’s biomes is structured by the match between climate and plant traits, which in turn shape associated communities and ecosystem processes and services. However, that climate–trait match can be disrupted by historical events, with lasting ecosystem impacts. As Earth’s environment changes faster than at any time in human history, critical questions are whether and how organismal traits and ecosystems can adjust to altered conditions. We quantified the relative importance of current environmental forcing versus evolutionary history in shaping the growth form (stature and biomass) and associated community of eelgrass ( Zostera marina ), a widespread foundation plant of marine ecosystems along Northern Hemisphere coastlines, which experienced major shifts in distribution and genetic composition during the Pleistocene. We found that eelgrass stature and biomass retain a legacy of the Pleistocene colonization of the Atlantic from the ancestral Pacific range and of more recent within-basin bottlenecks and genetic differentiation. This evolutionary legacy in turn influences the biomass of associated algae and invertebrates that fuel coastal food webs, with effects comparable to or stronger than effects of current environmental forcing. Such historical lags in phenotypic acclimatization may constrain ecosystem adjustments to rapid anthropogenic climate change, thus altering predictions about the future functioning of ecosystems.

Distribution of Earth’s biomes is structured by the match between climate and plant traits, which in turn shape associated communities and ecosystem processes and services. However, that climate–trait match can be disrupted by historical events, with lasting ecosystem impacts. As Earth’s environment changes faster than at any time in human history, critical questions are whether and how organismal traits and ecosystems can adjust to altered conditions. We quantified the relative importance of current environmental forcing versus evolutionary history in shaping the growth form (stature and biomass) and associated community of eelgrass ( Zostera marina ), a widespread foundation plant of marine ecosystems along Northern Hemisphere coastlines, which experienced major shifts in distribution and genetic composition during the Pleistocene. We found that eelgrass stature and biomass retain a legacy of the Pleistocene colonization of the Atlantic from the ancestral Pacific range and of more recent within-basin bottlenecks and genetic differentiation. This evolutionary legacy in turn influences the biomass of associated algae and invertebrates that fuel coastal food webs, with effects comparable to or stronger than effects of current environmental forcing. Such historical lags in phenotypic acclimatization may constrain ecosystem adjustments to rapid anthropogenic climate change, thus altering predictions about the future functioning of ecosystems.

Significance Consumption transfers energy and materials through food chains and fundamentally influences ecosystem productivity. Therefore, mapping the distribution of consumer feeding intensity is key to understanding how environmental changes influence biodiversity, with consequent effects on trophic transfer and top–down impacts through food webs. Our global comparison of standardized bait consumption in shallow coastal habitats finds a peak in feeding intensity away from the equator that is better explained by the presence of particular consumer families than by latitude or temperature. This study complements recent demonstrations that changes in biodiversity can have similar or larger impacts on ecological processes than those of climate.