Diurnal observations of sheltering behaviour in the coral reef sea cucumber Holothuria whitmaei

Management of commercial sea cucumber stocks relies, in part, on estimates of population densities which, in-turn, depend on knowledge of habitat preferences, and of the influence of biological cues on sheltering and/or aggregation behaviour. Here, we document a diurnal shift in the sheltering behav...

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Main Authors: Shiell, Glenn, Knott, B.
Format: Journal Article
Published: Elsevier BV 2008
Online Access:http://hdl.handle.net/20.500.11937/10116
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author Shiell, Glenn
Knott, B.
author_facet Shiell, Glenn
Knott, B.
author_sort Shiell, Glenn
building Curtin Institutional Repository
collection Online Access
description Management of commercial sea cucumber stocks relies, in part, on estimates of population densities which, in-turn, depend on knowledge of habitat preferences, and of the influence of biological cues on sheltering and/or aggregation behaviour. Here, we document a diurnal shift in the sheltering behaviour of the Pacific and eastern Indian Ocean black teatfish, Holothuria whitmaei, and discuss the implication of this behaviour for surface-based population density surveys. Diurnal studies of 30 black teat fish on Ningaloo Reef, Western Australia, found that the proportion of animals sheltered (and therefore hidden when viewed from directly above) was significantly greater in the morning (3-23%; AM_0830-1230 h) relative to the afternoon (0-6%; PM_1230-1730 h). As with sheltering behaviour, the straight-line distance between individual sea cucumber and the nearest shelter also showed marked diurnal variation, with animals observed at greater distances from shelter between 1230 and 1730 h (PM_4-22 cm; AM_1-7 cm). Based on these results, we suggest that surfaced-based census techniques (e.g. manta tows) may underestimate population densities if conducted during times of reduced activity and increased incidence of sheltering behaviour. Appropriate calibration factors for day-time black teatfish surveys are proposed. © 2007 Elsevier B.V. All rights reserved.
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spelling curtin-20.500.11937-101162017-10-02T02:28:09Z Diurnal observations of sheltering behaviour in the coral reef sea cucumber Holothuria whitmaei Shiell, Glenn Knott, B. Management of commercial sea cucumber stocks relies, in part, on estimates of population densities which, in-turn, depend on knowledge of habitat preferences, and of the influence of biological cues on sheltering and/or aggregation behaviour. Here, we document a diurnal shift in the sheltering behaviour of the Pacific and eastern Indian Ocean black teatfish, Holothuria whitmaei, and discuss the implication of this behaviour for surface-based population density surveys. Diurnal studies of 30 black teat fish on Ningaloo Reef, Western Australia, found that the proportion of animals sheltered (and therefore hidden when viewed from directly above) was significantly greater in the morning (3-23%; AM_0830-1230 h) relative to the afternoon (0-6%; PM_1230-1730 h). As with sheltering behaviour, the straight-line distance between individual sea cucumber and the nearest shelter also showed marked diurnal variation, with animals observed at greater distances from shelter between 1230 and 1730 h (PM_4-22 cm; AM_1-7 cm). Based on these results, we suggest that surfaced-based census techniques (e.g. manta tows) may underestimate population densities if conducted during times of reduced activity and increased incidence of sheltering behaviour. Appropriate calibration factors for day-time black teatfish surveys are proposed. © 2007 Elsevier B.V. All rights reserved. 2008 Journal Article http://hdl.handle.net/20.500.11937/10116 10.1016/j.fishres.2007.12.010 Elsevier BV restricted
spellingShingle Shiell, Glenn
Knott, B.
Diurnal observations of sheltering behaviour in the coral reef sea cucumber Holothuria whitmaei
title Diurnal observations of sheltering behaviour in the coral reef sea cucumber Holothuria whitmaei
title_full Diurnal observations of sheltering behaviour in the coral reef sea cucumber Holothuria whitmaei
title_fullStr Diurnal observations of sheltering behaviour in the coral reef sea cucumber Holothuria whitmaei
title_full_unstemmed Diurnal observations of sheltering behaviour in the coral reef sea cucumber Holothuria whitmaei
title_short Diurnal observations of sheltering behaviour in the coral reef sea cucumber Holothuria whitmaei
title_sort diurnal observations of sheltering behaviour in the coral reef sea cucumber holothuria whitmaei
url http://hdl.handle.net/20.500.11937/10116