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In Situ Measurement of Pinna nobilis Shells for Age and Growth Studies:
A New Device
Author(s) -
GarcíaMarch José Rafael,
Manuel GarcíaCarrascosa Antonio,
Luís Peña Álvaro
Publication year - 2002
Publication title -
marine ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.668
H-Index - 58
eISSN - 1439-0485
pISSN - 0173-9565
DOI - 10.1046/j.1439-0485.2002.02781.x
Subject(s) - posidonia oceanica , mediterranean sea , mediterranean climate , seagrass , potamogetonaceae , population , biology , ecology , bay , scuba diving , habitat , oceanography , fishery , geology , zoology , demography , sociology
.Pinna nobilisLinnaeus 1758 is an endemic bivalve mollusc in the Mediterranean Sea, where it inhabits seagrass meadows, especiallyPosidonia oceanica(L.) Delile. It is the largest bivalve in the Mediterranean, reaching lengths up to 120 cm. In its natural habitat,P. nobilislives with the anterior part of the valve buried in the seabed, attached toPosidoniarhizomes by byssus threads.
This habit makes it impossible to measure its total length directly in situ . As the only way to determine the individual age is the relationship between age and total length, several equations have been proposed to estimate total length by relating it to the unburied parts of the shell. Such measurements are essential to ecological studies that consider age, growth, and population dynamics, and that evaluate the environmental factors that affect this species.
Accurately estimating total length depends on the accuracy and precision of the method employed to measure the unburied shell parts. In this paper, we point out the lack of precision of the instruments and methods used until now; we also demonstrate the reason for this imprecision. A new device to measure unburied parts of Pinna nobilis with a precision comparable to that obtained when measuring extracted valves is described. This device is unaffected by substratum type and reduces measurement time. The latter is a very important feature, because these procedures are usually performed whilst SCUBA diving. Finally, a growth equation has been fitted to the measurements obtained with the new device from a population located in Moraira (Alicante, western Mediterranean).