Deep-sea biology food for thought? : examining dietary selection and resource allocation in deep-sea holothurians
Deep-sea biology food for thought? : examining dietary selection and resource allocation in deep-sea holothurians
This study examined the complex link between surface production and the feeding ecology of a range of holothurian species from both abyssal and bathyal depths on the PAP and PSB over 3 seasonal periods from Summer 2001 to Autumn 2002 using a range of biochemical techniques and novel experimental work.
The chlorophyll and carotenoid pigments taken from the gut contents of over 14 holothurian species showed significant between-species difference in the concentration, and to some extent composition of pigment. Individual species were shown to have subtly different preferences for different pigment biomarkers, derived from different types of OM contained within the seafloor sediment. One of the most noticeable differences occurred in Amperima rosea. The study showed that A. rosea had a consistently higher pigment concentration than all other abyssal species during all the sampling periods. The pigment composition was also significantly different, with large concentrations of zeaxanthin, echinenone and β-carotene. Examining the remaining abyssal species, showed that A. rosea was able to feed preferentially upon the labile fractions of the sediment, leaving the more refractory breakdown products for the other species to utilise.
Trends within bathyal species were somewhat different. Most bathyal species had similar pigment compositions, but there were significant differences in overall pigment concentration. As species were sampled with increasing depth down the continental slope, the pigment concentration found within the gut contents of different holothurian species increased, with highest concentrations in Benthothuria funebris, sampled from 3000m.
The pigment concentrations of both bathyal and abyssal holothurians showed marked seasonal patterns. In periods during, and directly after, spring blooms, the concentration of pigments within gut contents was an order of magnitude higher than in pre-bloom periods.
To determine how holothurians assimilate and utilise labile OM, gonadal material from bathyal and abyssal species was examined. From a suite over 10 pigments ingested, only a small number were found within the gonad, most notably echinenone and β-carotene. These labile carotenoids were concentrated in the gonad by an order of magnitude when compared with levels in gut contents. These carotenoids are used in aquaculture to stimulate increased egg production and growth. The high level of these carotenoids in deep-sea holothurians suggests they rely upon OM flux to provide key biochemical components crucial for reproduction and development.
Using a fatty acid biomarker approach, a similar seasonal pattern in the dietary requirement of holothurians was shown. All species selected polyunsaturated fatty acids (PUFAs) in preference to other groups of lipid. The highest levels of PUFA coincided with the arrival of OM associated with the spring bloom, much in the same way as pigment concentrations, especially labile carotenoids also increased.
University of Southampton
2004
Hudson, Ian Richard
(2004)
Deep-sea biology food for thought? : examining dietary selection and resource allocation in deep-sea holothurians.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
This study examined the complex link between surface production and the feeding ecology of a range of holothurian species from both abyssal and bathyal depths on the PAP and PSB over 3 seasonal periods from Summer 2001 to Autumn 2002 using a range of biochemical techniques and novel experimental work.
The chlorophyll and carotenoid pigments taken from the gut contents of over 14 holothurian species showed significant between-species difference in the concentration, and to some extent composition of pigment. Individual species were shown to have subtly different preferences for different pigment biomarkers, derived from different types of OM contained within the seafloor sediment. One of the most noticeable differences occurred in Amperima rosea. The study showed that A. rosea had a consistently higher pigment concentration than all other abyssal species during all the sampling periods. The pigment composition was also significantly different, with large concentrations of zeaxanthin, echinenone and β-carotene. Examining the remaining abyssal species, showed that A. rosea was able to feed preferentially upon the labile fractions of the sediment, leaving the more refractory breakdown products for the other species to utilise.
Trends within bathyal species were somewhat different. Most bathyal species had similar pigment compositions, but there were significant differences in overall pigment concentration. As species were sampled with increasing depth down the continental slope, the pigment concentration found within the gut contents of different holothurian species increased, with highest concentrations in Benthothuria funebris, sampled from 3000m.
The pigment concentrations of both bathyal and abyssal holothurians showed marked seasonal patterns. In periods during, and directly after, spring blooms, the concentration of pigments within gut contents was an order of magnitude higher than in pre-bloom periods.
To determine how holothurians assimilate and utilise labile OM, gonadal material from bathyal and abyssal species was examined. From a suite over 10 pigments ingested, only a small number were found within the gonad, most notably echinenone and β-carotene. These labile carotenoids were concentrated in the gonad by an order of magnitude when compared with levels in gut contents. These carotenoids are used in aquaculture to stimulate increased egg production and growth. The high level of these carotenoids in deep-sea holothurians suggests they rely upon OM flux to provide key biochemical components crucial for reproduction and development.
Using a fatty acid biomarker approach, a similar seasonal pattern in the dietary requirement of holothurians was shown. All species selected polyunsaturated fatty acids (PUFAs) in preference to other groups of lipid. The highest levels of PUFA coincided with the arrival of OM associated with the spring bloom, much in the same way as pigment concentrations, especially labile carotenoids also increased.
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Published date: 2004
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Local EPrints ID: 465283
URI: http://eprints.soton.ac.uk/id/eprint/465283
PURE UUID: 141169ff-4d47-4f96-8486-8cb021740f3a
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Date deposited: 05 Jul 2022 00:34
Last modified: 05 Jul 2022 00:34
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Author:
Ian Richard Hudson
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