Population Demographics of Golden Tilefish \u3cem\u3eLopholatilus chamaeleonticeps\u3c/em\u3e in the Gulf of Mexico

The Deepwater Horizon (DWH) oil spill had catastrophic impacts on aquatic organisms in the Northern Gulf of Mexico (GoM). Longline gear was used to sample demersal fish species at 344 locations distributed throughout the GoM in the seven years following DWH. Sampling was accomplished deploying 450-500 baited hooks per station in depths ranging from 20-600 m. Using data from these surveys, I analyzed the length and age frequency, condition, growth, and mortality rates of Golden Tilefish (Lopholatilus chamaeleonticeps) throughout the GoM. Demersal habitat use and apparent high contaminant levels in Golden Tilefish makes them potentially vulnerable to oil spills such as DWH. Therefore, comparing population resiliency by analyzing rates of growth and mortality is an obvious methodology for understanding the effects of anthropogenic perturbations and how vital rates vary spatially. Comparisons were also made by country of origin in order to establish a baseline dataset for the southern GoM. Although there is spatial and temporal variation in some length distribution, condition, and growth metrics, other metrics show no difference among Golden Tilefish by country of origin, site location relative to the DWH spill perimeter, and in pre- and post-spill comparisons. Golden Tilefish grow slightly faster off Mexico than in the Northern GoM, however the total mortality rate (Z), determined via catch curve analysis, was higher off Mexico than in the United States. Growth curves fit to length-at-age data from the DWH spill site and all other US sites post-spill showed slight differences, although those differences decreased in pre- and post-DWH spill site comparisons. Although the total mortality rate was much higher in fish from the DWH spill perimeter compared to all other US sites, there was no discernable difference in Z occurred pre- vs. post-spill. Thus, any differences in growth and mortality observed in post-spill fish from the DWH spill perimeter compared to post-spill fish from elsewhere in the US appear to be endemic to the northeastern Gulf of Mexico. While further study is needed to analyze the impacts from oil exposure on eggs and larvae on population demographics, Adult Golden Tilefish appeared to be resilient against DWH oil exposure

Ice Formation and the Risk of Chloride Toxicity in Shallow Wetlands and Lakes

The process of ice formation in shallow waterbodies can increase chloride to toxic levels in waterbodies already impacted by chloride loading from road salt (NaCl deicer) application. Chloride concentrations were measured bi-weekly in a shallow, urban wetland in Madison, Wisconsin. We found that in this shallow waterbody, ice thickening doubled chloride concentrations from ion exclusion as the water froze. To understand the role of ice formation and ion exclusion, we constructed a numerical model to predict chloride concentrations beneath the ice resulting from ion exclusion. Where chloride levels already are elevated above background and flushing rates are low, ice thickening can push concentrations well above toxicity thresholds for much of the winter. The compounding effects of road salt runoff and ice formation should be considered in the management of water quality and ecosystem health in shallow urban water bodies or waterbodies receiving road salt runoff from nearby roadways

Ice Formation and the Risk of Chloride Toxicity in Shallow Wetlands and Lakes

The process of ice formation in shallow waterbodies can increase chloride to toxic levels in waterbodies already impacted by chloride loading from road salt (NaCl deicer) application. Chloride concentrations were measured bi-weekly in a shallow, urban wetland in Madison, Wisconsin. We found that in this shallow waterbody, ice thickening doubled chloride concentrations from ion exclusion as the water froze. To understand the role of ice formation and ion exclusion, we constructed a numerical model to predict chloride concentrations beneath the ice resulting from ion exclusion. Where chloride levels already are elevated above background and flushing rates are low, ice thickening can push concentrations well above toxicity thresholds for much of the winter. The compounding effects of road salt runoff and ice formation should be considered in the management of water quality and ecosystem health in shallow urban water bodies or waterbodies receiving road salt runoff from nearby roadways