Natal elemental signatures in the otoliths of Lipophrys pholis (Pisces: Blenniidae)

Larval dispersal is a fundamental form of connectivity in the marine environment but in spite of its importance to biogeography, population dynamics and resilience, it is little studied and poorly estimated due to the... [ view full abstract ]

Larval dispersal is a fundamental form of connectivity in the marine environment but in spite of its importance to biogeography, population dynamics and resilience, it is little studied and poorly estimated due to the complexity and variability of the multitude of processes involved. One important gap in our knowledge is caused by our inability to track the multitude of microscopic larvae from a spawning site to a recruitment site. Recent advances in the use of natural tags show great promise in identifying the place of origin of dispersing larvae. Calcified structures such as otoliths have capacity to reflect in their chemistry the physiochemical properties of the surrounding seawater at the time they were formed. In this study we show that embryonic otoliths of the blennid fish Lipohrys pholis retain natal geochemical signatures that can be used to identify the potential source populations of dispersing larvae. Using laser ablation - inductively coupled plasma - mass spectrometry (LA-ICP-MS), we measured the concentration of 12 elements (Li, B, Mg, P, S, K, Mn, Cu, Zn, Sr, Ba, Pb) in the embryonic otoliths of L. pholis from 20 sites within 3 regions of the Portuguese coast. We found significant spatial variation in otolith geochemical signatures and show that these elemental fingerprints can be used to discriminate with a high degree of confidence between sites separated by 10s to 100s of km. The atlas of natal geochemical signatures in the otoliths of L. pholis generated in this study will be used in the construction of empirical connectivity matrices by assigning the recruits of this species to their correspondent natal populations based on the match of their otolith core signatures to the embryonic otolith signatures.