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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, tevans03@syr.edu
2CARY
Institute, 2801 Sharon Turnpike, P.O. Box AB, Millbrook, NY,
12545-0129, audelochet@gmail.com
3SUNY ESF, 249 Illick Hall, 1 Forestry Drive,
Syracuse, NY, 13210, klimburg@esf.edu
October 2015
ABSTRACT:
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.