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Changing climatic conditions can have complex effects on the biomineralized segments of marine organisms, which in turn may influence individual fitness and survival. In nacreous shells, tablet thickness is one microstructural component that has been observed to positively correlate with ocean temperature, though the strength of this relationship is unclear, leaving unresolved whether temperature is a consistent predictor of tablet thickness and, if so, over what scales. Here we investigate the relationship between tablet thickness and temperature in two nacre-producing marine mollusks in the modern ocean. We explore the relationship between nacre tablet thickness and ocean temperature through a global analysis of present-day abalone (Haliotis) nacre, and a temporal analysis of nut clam (Nucula proxima) nacre using shells from individuals that lived before and after 1950 in two regions of the Gulf of Mexico. We document a positive relationship between tablet thickness and ocean temperature within and among closely-related species. For a given temperature, considerable variation was observed in nacre tablet thickness, indicating that other factors also contribute. While increased temperature is likely to cause larger biomineralized units within the calcified segments of marine organisms, other environmental factors might counter those changes, highlighting the need for work exploring the multimodal impact of anthropogenic climate change on biominerals. 

Climate and ecosystem dynamics vary across timescales, but research into climate-driven vegetation dynamics usually focuses on singular timescales. We developed a spectral analysis–based approach that provides detailed estimates of the timescales at which vegetation tracks climate change, from 10¹to 10⁵years. We report dynamic similarity of vegetation and climate even at centennial frequencies (149⁻¹to 18,012⁻¹year⁻¹, that is, one cycle per 149 to 18,012 years). A breakpoint in vegetation turnover (797⁻¹year⁻¹) matches a breakpoint between stochastic and autocorrelated climate processes, suggesting that ecological dynamics are governed by climate across these frequencies. Heightened vegetation turnover at millennial frequencies (4650⁻¹year⁻¹) highlights the risk of abrupt responses to climate change, whereas vegetation-climate decoupling at frequencies >149⁻¹year⁻¹may indicate long-lasting consequences of anthropogenic climate change for ecosystem function and biodiversity. 

The Mississippi River watershed drains 40% of the continental United States, and the tremendous primary productivity in the adjacent north-central Gulf of Mexico has created one of the most extensive dead zones on Earth. In contrast, smaller watersheds deliver fewer nutrients to the northeastern gulf, and consequently, productivity is limited and hypoxia is uncommon. How has variation in primary productivity, oxygen availability, and sea-surface temperature affected coastal food webs? Here, we investigate environmental controls on the size of molluscan predators and prey in the northern Gulf of Mexico using Holocene death assemblages. Linear mixed models indicate that bivalve size and the frequency of drilling predation are affected by dissolved oxygen concentrations; drilling frequency declines with declining oxygen, whereas bivalve size increases. In contrast, sea-surface temperature is positively associated with the size of molluscan predators and prey. Net primary productivity contributes relatively little to predator or prey size, and predator-to-prey size ratios do not vary consistently with environmental conditions across the northern gulf. Larger bivalves in areas of oxygen limitation may be due to decreased predation pressure and, consequently, greater prey longevity. The larger size of bivalves and predatory gastropods in warmer waters may reflect enhanced growth under these conditions, provided dissolved oxygen concentrations exceed a minimum threshold. Holocene death assemblages can be used to test long-standing hypotheses regarding environmental controls on predator−prey body-size distributions through geologic time and provide baselines for assessing the ongoing effects of anthropogenic eutrophication and warming on coastal food webs.