Evaluation of periodic and aperiodic otolith structure and somatic-otolith scaling for use in retrospective life history analysis of a tropical marine goby, Bathygobius coalitus

Abstract

Daily increment formation in sagittal otoliths, scaling between otolith and somatlc growth. and the temporal link between settlement and formation of a settlement mark in otolith structure were evaluated for their use in reconstructing aspects of the early Me history of the basalt goby Bathygobius coalitus. Formation of daily increments was validated in sagittae of fish ranging In Life history stage from new recruits to sexually differentiated males and females. Total length (TL) was proportional to other measures of body length, width, and depth, and linearly proportionaI to sagitta radius for fish between 8 and 40 mm TL. Somatic-otolith scaling became more curvilinear in larger fish due to declining growth rate of otoliths relative to TL, especially in fish collected during warmer sea surface temperatures. For fish 8 to 40 mm TL, somatic-otolith scaling was not affected by differential somatic growth rates nor by seasonal water temperature. A settlement mark, clearly identifiable as a distinct and abrupt shift in optical focal plane, contrast, and width of daily increments, was venfied to coincide with settlement. Wider post-settlement increments abruptly followed narrower pre-settlement increments across the settlement mark. These results support the use of daily increments, somatic-otolith scaling, and a settlement mark for reconstruction of hatch and settlement dates, mean daily pre-and post-settlement growth rates, size and age at settlement, and post-settlement size-at-age histories for the basalt goby.

Habitat- and sex-specific life history patterns of yellow tang Zebrasoma flavescens in Hawaii, USA

“…Only otolith preparations that provided clear transects from core to edge were used in analyses. While daily increment formation in yellow tang was not validated in the present study, we are confident in our interpretation because it has been validated for 2 congeners, Zebrasoma scopus and Z. veliferum, at Lizard Island, Australia (Lou & Moltschaniwskyj 1992), and for a number of other coral reef fishes in Hawaii (Danilowicz 1997, Shafer 2000.…”

“…Only otolith preparations that provided clear transects from core to edge were used in analyses. While daily increment formation in yellow tang was not validated in the present study, we are confident in our interpretation because it has been validated for 2 congeners, Zebrasoma scopus and Z. veliferum, at Lizard Island, Australia (Lou & Moltschaniwskyj 1992), and for a number of other coral reef fishes in Hawaii (Danilowicz 1997, Shafer 2000.Habitat use modeling. Median size and age at which yellow tang make an ontogenetic shift in daytime habitat use was estimated by adapting methods developed for estimating size or age at 50% reproductive maturity (Welch & Foucher 1988, Roa et al 1999.…”

“…These recruit otoliths were also ground to produce a transverse section, but grinding was performed by hand and finished by polishing with alumina polish. Counts of daily increments were conducted by a single observer (D. J. Shafer) following standardized procedures (Shafer 2000). Only otolith preparations that provided clear transects from core to edge were used in analyses.…”

Otolith-check formation and accelerated growth associated with sex change in an annual protogynous tropical fish

“…However, the present study suggests that P. cylindrica differs from the tropical annual gobiids with respect to age-and sex-specific growth rates. Gobiopterus mindanen, Favonigobus reichei, Glossogobius biocellatus (Schläppy 1997), Bathygobius coalitus (Shafer 2000), and Istigobius decoratus (Kritzer 2002) all have linear length-at-age trajectories, with males following the female growth pattern after sex change. In contrast, the von Bertalanffy growth model was found the best descriptor of length-age data for P. cylindrica.…”

“…These display rapid growth, a linear relationship between otolith and somatic growth, high reproductive investment, and longevities spanning no longer than 2.5 yr (Schläppy 1997, Munday & Jones 1998, Shafer 2000, Kritzer 2002). P. cylindrica had a maximum longevity of 326 d at Orpheus Island and 411 d at One Tree Island.…”