Trophic Structure, Feeding Ecology, and Bioaccumulation of Mercury in Gulf of Mexico Hagfishes, 2011-2014

Hagfishes (Myxinidae) are common in deep waters of the Gulf of Mexico (GoM). Two out of the three species found in the GoM are endemic and potentially provide key ecosystem services (e.g. generate substrate turnover and recycling of organic matter by consuming carrion falls) and yet very little is known about their life histories and ecology. The objective of this study is to investigate inter and intraspecific variations in trophic structure, feeding ecology and bioaccumulation of mercury (Hg) of Eptatretus springeri, Eptatretus minor, Myxine mcmillanae including variations along relevant environmental gradients as well as potential shifts in Hg bioaccumulation levels caused by the changing conditions that originated after the 2010 Deep Water Horizon (DWH) oil spill. The objective is to test the hypothesis these hagfish species exhibit varying feeding strategies which may be influenced by changing environmental conditions. These variations in feeding ecology would place each species at different trophic levels in the GOM deep-sea food web. Consequently, these differences in feeding ecology and trophic structure could signify inter and intraspecific variations in bioaccumulation levels of Hg. To test these hypotheses, the trophic structure and feeding ecology of these species will be described using an approach using stable isotope analysis (SIA) of carbon (δ13C), nitrogen (δ15N) and sulfur (δ34S). Total Hg (THg) and Methyl-Mercury (MeHg) concentrations in muscle tissues will be measured via cold vapor fluorescent mass spectrometry and combined with SIA to identify the influence of trophic structure in Hg accumulation. To test whether the change in substrate conditions after the DWH oil spill had potential effects on Hg levels in muscle tissue, we will compare Hg levels of hagfish from areas of different levels of exposure to the oil released by DWH. Quantifying variation in trophic dynamics and feeding ecology of ecosystem service providers such as hagfish, could help better understand their importance in the ecosystems in which they inhabit.