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+--- Thread: Sepioteuthis Australis Paper (/thread-2336.html)
Sepioteuthis Australis Paper - glen - 14-09-2004
TI: Title
Are bigger calamary Sepioteuthis australis hatchlings more likely
to survive? A study based on statolith dimensions
AU: Author
Steer, MA; Pecl, GT; Moltschaniwskyj, NA
SO: Source
Marine ecology progress series [Mar. Ecol. Prog. Ser.]. Vol. 261,
pp. 175-182. 2003.
AB: Abstract
To determine whether any size-selective processes were operating
throughout the life history of squid, this study set out to
ascertain whether bigger hatchlings are more likely to survive to
adulthood. This was achieved by comparing natal statolith
dimensions between recently hatched (< 13 h old) and successfully
recruited adult Sepioteuthis australis. The squid statolith
(analogous to the teleost otolith) retains a check associated with
hatching, and the natal radius (NR) at hatching had a strong
linear relationship to dorsal mantle length (ML). Hatchlings were
collected using emergent traps from October 2001 to February 2002
on natural spawning grounds located on the east coast of Tasmania.
Hatchling size was extremely variable ranging from 4.3 to 7.3 mm
(ML), with significantly larger squids hatching out in November
and the smallest in February. From February to August, adults were
collected from the same bay and aged using validated daily rings
in the statolith and those adults estimated to have been born
between October and February were included in the analysis. In all
but 1 mo, a significant difference between the NR size
distributions of the hatchlings and adults was detected due to low
numbers of adults with small NRs. This indicated that smaller
hatchlings were less likely to recruit, suggesting that there is
an element of size-mediated mortality operating on populations of
S. australis.
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Glossary/Definitions
statolith - 1. zoology granules within a statocyst: any of the tiny bony granules that are suspended in fluid within a statocyst and whose movement is detected by sensory hairs that determine an invertebrateââ¬â¢s position.
(Also called otolith)
statocyst - invertebrate sensory organ: a fluid-filled organ of balance in some invertebrates such as the lobster containing suspended bony granules that, along with sensory cells, help it to determine its position.
(Also called otocyst)