Mechanisms underlying natural variation in otolith elemental fingerprints of larval lake whitefish

Fish otolith elemental composition is used to infer natal origins and
early life histories, but the relative roles of environmental exposure
versus maternal influences remain uncertain for many species. We examined
otolith elemental fingerprints of larval lake whitefish (Coregonus
clupeaformis) in Green Bay, Lake Michigan, finding two distinct
geochemical groupings among wild-caught larvae. To identify mechanisms
generating this variation, we conducted a reciprocal transplant experiment
testing whether incubation environment drives larval otolith signatures.
Larval signatures differed primarily by maternal spawning origin, while
incubation environment contributed minimally. Classification analyses
showed high assignment success to maternal source, with most
misclassification among groups sharing maternal origin. These results
indicate that maternally associated chemical signatures dominate larval
otolith fingerprints through early development, complicating
interpretation of larval otolith chemistry as a "natal
environment" signal. Our findings clarify when larval signatures
likely reflect maternal provenance versus environmental exposure and
highlight the need for additional reference collections and temporal
validation to strengthen natal assignment frameworks in the Great Lakes.