Increasing surface sea temperatures are increasingly impacting marine and coastal environments. Bioindicator species can be used to discern broad patterns about global climate changes that are applicable to many taxa. In addition to being a bioindicator species, Atlantic sea urchins (add scientific name) also have relatively simple systems with few internal mechanisms that could confound observed responses. We tested the effect of temperature on reproductive functions, nitrotyrosine protein expression, heat shock protein expression, and coelomic fluid (CF) conditions in Atlantic sea urchin. Ten sea urchins were placed in each of six 20-gallon aquariums set to 32oC, 28oC, or 24oC (control) under controlled laboratory conditions for a 7-day period. Male and female sea urchins exposed to the high temperatures had lower gonadal growth compared to those exposed to the control temperature. The percentage of mature ova was significantly lower at high temperatures compared to the control temperature, indicating impaired ovarian functions at elevated temperatures. There was an inverse relationship between sperm production and temperature. Sea urchin exposed to high temperatures showed an increase in nytrotyrosine expression and heat shock protein expression in ova, follicles, and sperm, as well as increased cellular apoptosis and decreased CF pH compared to controls. These results suggest that elevated water temperature decline/acidify CF pH which might be involved in the impairment of reproductive functions and cellular apoptosis in Atlantic sea urchin.