Temperature

Microplastics are a ubiquitous pollutant that has emphasized major concern for several benthic ecosystems and for the species that inhabit them especially as temperatures have begun to warm at an exponential rate. This study has investigated the abundance and trophic transfer intensity of microplastics through exposure experimentation to two different benthal organisms, the stone crab (Menippe mercenaria) and hard clam (Mercenaria mercenaria), under three different temperature gradients. Within a laboratory setting, hard clams were exposed to a concentration of different sizes and types of microplastics in three different temperatures to observe the accumulation rate of these particles from direct ingestion. The exposed clams were then fed to predatory stone crabs from the Indian River Lagoon, under the same three temperature treatments, to detect MP trophic transfer. To examine the disposition of ingested plastics, histology and fluorescent microscopy were used to quantify the locations and numbers of microplastics in the tissues.

Inductive and model-tree (MT) approach-based models are developed and evaluated for forecasting mean, minimum and maximum monthly temperature in this study. The models are developed and tested using long-term historical temperature time series data derived from U.S. Historical Climatology Network at 22 sites located in the state of Florida. Inductive models developed include conceptually simple naïve models to multiple regression models utilizing lagged temperature values, sea surface temperatures (SSTs), correction factors derived using historical data. A global model using data from all the sites is also developed. The performances of the models were evaluated using observed temperature records and several error and performance measures. A composite measure combining multiple error and performance measures is developed to select the best model. MT approach-based and regression models with SSTs and correction factors along with lagged temperature values are found to be best models for forecasting temperature based on assessments of composite measures and error diagnostics.

Under the expected warmer temperatures due to climate change, sea turtle embryos may be subjected to thermal conditions detrimental to nest success and hatchling quality; one trait which may be negatively affected is cognitive ability. In this study, loggerhead sea turtle eggs were acquired from Boca Raton, FL and lab incubated under two female-producing temperatures: an “optimal” temperature of 31°C and a sublethal temperature of 33°C. Cognitive ability of post-hatchlings, assessed via associative learning and reversal was investigated using a y-maze. The sublethal temperature decreased incubation duration, hatch success, hatchling growth rates and produced smaller hatchlings with significantly more scute anomalies. Hot hatchlings performed worse on the reversal, taking longer to train, and thus hint at an effect of incubation temperature on cognitive flexibility in loggerhead turtles. With temperatures rising on beaches in South Florida, this study provides evidence of further potential threats to hatchling quality and potentially even survival.

Climate change has the potential to expose sea turtle nests to higher temperatures, which may negatively impact sea turtle hatchling vigor. In this study, loggerhead and green hatchlings were sampled from the Boca Raton, Florida beach and via lab incubation, and hatchling vigor was determined. Elevated nest temperatures decreased loggerhead and green turtle hatchling performance and corticosterone levels, with the most significant effects found in hatchlings exposed to maximum incubation temperatures above 35°C during late development. Lab-incubated loggerhead post-hatchling corticosterone levels and growth rates were also determined. The differences seen in corticosterone levels with overall nest incubation temperatures, mean temperatures during early, middle or late stages of development, and its negative correlation with hatchling performance improves our understanding of the underlying physiological mechanisms linking elevated incubation temperatures and sub-lethal physiological effects that may significantly impact hatchling survival, a critical step for sea turtle conservation in south Florida and elsewhere.