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DETERMINING IF EYE LENSES CAN BE USED TO UNDERSTAND THE ORIGIN AND LIFE HISTORY OF ADULT LAMPREY
1SUNY ESF, 144 Illick Hall, 1 Forestry Drive, Syracuse, NY, 13210, firstname.lastname@example.org
2CARY Institute, 2801 Sharon Turnpike, P.O. Box AB, Millbrook, NY,
3SUNY ESF, 249 Illick Hall, 1 Forestry Drive, Syracuse, NY, 13210, email@example.com
Sea lamprey (Petromyzon marinus) invaded the upper Laurentian Great Lakes and fundamentally altered the structure and function of the ecosystem. Control efforts have been successful at limiting their numbers by targeting larvae in tributaries before they enter the Lakes. However, identification of which rivers produce the most sea lamprey parasites and the efficiency of control treatments in different tributaries is difficult because parasitic individuals cannot be assigned to a natal stream. Therefore, developing a method to identify parasitic sea lamprey natal origin is a high priority for management of the species in the Great Lakes.
There has been a recent interest in using calcified structures to identify sea lamprey natal origin. Natural chemical tags recorded in statoliths, calcified structures in the inner ear of sea lamprey, have been used with limited success as an indicator of sea lamprey natal origin. Like statoliths, eye lenses grow throughout life, but unlike the former, they are made of protein rather than calcium phosphate (apatite). The objective of our pilot study was to test the potential of eye lenses to determine sea lamprey natal origin. We examined lens chemistry from 123 sea lamprey lenses from the Great Lakes region, Lake Champlain, and the Connecticut River. Eleven elements were measured (24Mg, 43Ca, 55Mn, 56Fe, 64Zn, 65Cu, 85Rb, 88Sr, 138Ba, 202Hg, 208Pb) using laser ablation inductively coupled plasma mass spectrometry (LA ICP-MS). Natal origin classification reached 67% (for individual streams) and 64% (when streams were grouped within basins). We were able to correctly classify animals to their collection location on average 67% (range: 40-90%) of the time with quadratic discrimination analysis. We found the isotopes 24Mg and 55Mn to be most useful in classification. We also tested the effect of ethanol on lens chemistry. Even short exposure to ethanol appears to lower the concentration of some of the measured elements and we recommend avoiding use of ethanol in the preservation or preparation of lens samples. The chemistry of lenses provides insight into the natal origin of lamprey, although more work is required to understand the stability and long term changes that occur in lamprey lens chemistry.