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Natural growth lines in echinoid ossicles are not reliable indicators of age: a test using Strongylocentrotus droebachiensis
Author(s) -
Russell Michael P.,
Meredith Robert W.
Publication year - 2000
Publication title -
invertebrate biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.486
H-Index - 42
eISSN - 1744-7410
pISSN - 1077-8306
DOI - 10.1111/j.1744-7410.2000.tb00111.x
Subject(s) - strongylocentrotus droebachiensis , biology , ossicles , sea urchin , population , ossicle , skeleton (computer programming) , anatomy , zoology , ecology , middle ear , demography , sociology
. Natural growth lines in the ossicles of echinoids have been used to estimate age, calculate growth curves, and infer population age‐structure. However, few studies evaluate whether these bands are added annually–a critical assumption of the aging technique. We tested whether the banding pattern is annual in Strongylocentrotus droebachiensis. Sea urchins were tagged with a fluorescent marker, released into tidepools, and collected 1 year later. We quantified the position of the fluorescent mark relative to subsequent growth bands. In 30 individuals ranging in test diameter from 14 to 77 mm, and in a series of ∼2 mm size intervals, we examined 3 interambulacral plates (aboral, ambital, and oral) and a rotula from Aristotle's lantern. Overall, only 7 sea urchins (23%) added a complete band to all 4 ossicles. In 6 sea urchins (20%) at least 1 ossicle added more than 1 complete band. In many sea urchins, especially those >55 mm in diameter, most ossicles added less than 1 band. The banding pattern in ossicles seriously underestimates age in S. droebachiensis and population parameters inferred from these growth lines are biased. Before using the growth‐band aging method in other echinoids, it must be demonstrated that 1 band is added annually for all sizes in a population under field conditions.