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Exploring factors impacting long-term temperature trends in U.S. estuarine and coastal waters
Citation:
Pelletier, Peg, C. Brown, Jim Hagy, Jim Kaldy, A. Oczkowski, AND H. Plaisted. Exploring factors impacting long-term temperature trends in U.S. estuarine and coastal waters. 14th National Monitoring Conference, Green Bay, WI, March 10 - 14, 2025.
Impact/Purpose:
Climate change is associated with increasing air and water temperature. However, this warming is not evenly distributed in space and time. For example, warming is more pronounced in higher latitudes and in shallow waters. This shallow water enhancement may adversely impact early life stages of aquatic organisms and the condition of seagrass habitats. In this study we compiled long-term temperature records from estuaries and coastal waters in the Atlantic Ocean, Pacific Ocean, and Gulf of Mexico to understand how warming varies spatially, and what factors are most important to explain observed warming patterns.
Description:
Climate-based warming has been affecting our coastal waters for decades, and there is some limited information suggesting that this warming may be enhanced in nearshore shallow waters. These areas are often important nursery areas and may support seagrass habitat. In contrast, monitoring data and buoys are often located in deeper, more centrally located ‘representative’ areas in estuaries. To assess whether shallow-water warming was a universal phenomenon, we compiled recent, long term (generally 15-20 years) data from 187 monitoring buoys and instruments from coastal waters in the United States. The sensors were deployed at depths of 0 (surface) to 7.3 m, in water depths ranging from 0.25 to 1000 m. Buoys and instruments were located from the landward limit of estuaries seaward to offshore coastal waters. Multiple metrics were extracted from these temperature time series including the rate of increase over time, both yearly and seasonally, and the frequency of exceeding temperature thresholds expected to adversely impact seagrasses. We compiled other data typically associated with water temperature including ecoregion, latitude, air temperature, distance from shore, estuary position, tidal height, and day length. In this presentation we explore the relationships between these temperature metrics and the variables associated with temperature. For example, although temperature increases are more dramatic at higher latitudes, we expect that this trend will be modified by location (e.g., Atlantic vs. Pacific). This initial evaluation will be used to define a model that can be used to quantify the relative importance of each of these factors.
