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Aquaculture 187 2000 85–96 www.elsevier.nl
rlocateraqua-online
Evaluation of diets for culture of the calanoid copepod Gladioferens imparipes
M.F. Payne , R.J. Rippingale
School of EnÕironmental Biology, Curtin UniÕersity of Technology, GPO Box U1987, Perth, Western Australia 6845, Australia
Accepted 9 December 1999
Abstract
Provision of copepod nauplii as food increases larval survival in many fish species that are difficult to rear using standard practices. Gladioferens imparipes is a temperate estuarine calanoid
copepod with culture potential. Diets were tested to determine which would maximise copepod production. Copepods were fed five diets: Isochrysis galbana, Chaetoceros muelleri, Dunaliella
tertiolecta, Nannochloropsis oculata and baker’s yeast. Copepod survival, time to maturity, maturation rate, nauplius production and female length were recorded at 208C and 258C. By most
criteria, Isochrysis was the most efficacious diet, followed by Chaetoceros and then Dunaliella. Nannochloropsis and yeast resulted in little or no survival. Fatty acid profile of each diet was
determined. In general, copepod production was positively related to the ratio of DHA:EPA in their diet. Poor survival on Nannochloropsis was probably a result of the small cell size and poor
digestibility of this species. q 2000 Elsevier Science B.V. All rights reserved.
Keywords: HUFA; Calanoid; Copepod; Algae; Culture; Diet
1. Introduction
For many fish species, hatchery production is uneconomical or impossible using either rotifers or Artemia as larval diets. This is mostly a result of poor survival at the
first feeding stage. The provision of copepod nauplii in the early larval diet often
Corresponding author. Tel.: q61-8-9266-7915; fax: q61-8-9266-2495.
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E-mail address: epayne2cc.curtin.edu.au M.F. Payne . 0044-8486
r00r - see front matter q 2000 Elsevier Science B.V. All rights reserved. Ž
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increases survival in these fish. Species in which this has been recently demonstrated Ž
. Ž
. include red snapper Doi et al., 1994 and some of the groupers Doi et al., 1997 . Also,
the provision of copepods in the early larval diet decreases malpigmentation in halibut Ž
. Ž
. McEvoy et al., 1998 and increases stress resistance in mahi-mahi Kraul et al., 1993 .
These improvements are mostly attributed to increased feeding by fish on copepods and the high nutritional content of copepods.
Copepod culture must demonstrate reliable and prolific production to be accepted as part of commercial operations. Both calanoid and harpacticoid copepods have been
cultured for use in fish larviculture. Harpacticoids are amenable to high-density culture conditions, hence, they are the subject of most studies on intensive copepod culture
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e.g., Sun and Fleeger, 1995; Støttrup and Norsker, 1997; Nanton and Castell, 1998 . However, harpacticoid copepods are predominantly benthic and so are not readily
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available to fish larvae that feed in the water column Kitajima, 1973 . In contrast, calanoid copepods are almost entirely planktonic, making them more suitable for feeding
to larval fish. However, production from calanoid copepod cultures is typically much Ž
. lower than that from harpacticoid cultures Støttrup et al., 1986; Schipp et al., 1999 .
Calanoid copepod production is limited by difficulties in maintaining broodstock at high densities. Stress caused by crowding decreases fecundity in the calanoid Cen-
Ž .
tropages typicus Miralto et al., 1996 . Also, cannibalism of nauplii by adults reduces Ž
. production in dense cultures. Rippingale and MacShane
1991 have identified a
temperate estuarine species, Gladioferens imparipes, that exhibits high nauplius produc- tion at relatively high broodstock densities when cultured on a small scale and does not
consume its own nauplii. While late copepodid and adult stages of this calanoid species Ž
. adhere to surfaces, nauplii are entirely pelagic Rippingale, 1994 .
To increase the scale of G. imparipes cultivation, algal diets that maximise copepod growth, survival and fecundity must be identified. Diets that are high in highly
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unsaturated fatty acids HUFAs maximise fecundity in the calanoid Acartia tonsa Ž
. Støttrup and Jensen, 1990 and are generally the choice of diet for calanoid cultivation
Že.g., Rippingale and MacShane, 1991; Klein Breteler and Laan, 1993; Schipp et al., .
Ž .
1999 . More specifically, the dietary ratio of two HUFAs, docosahexaenoic acid DHA Ž
. Ž
and eicosapentaenoic acid EPA , may affect copepod fecundity Støttrup and Jensen, .
1990 A wide range of algal species from different taxonomic groups are in common use in
aquaculture, each with specific nutritional characteristics. Four algal species from different groups were fed to copepods in the present work: the prymnesiophyte
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Isochrysis galbana T-Iso , the diatom Chaetoceros muelleri, the chlorophyte Dunaliella Ž
tertiolecta and the eustigmatophyte Nannochloropsis oculata. Baker’s yeast Sac-
. charomyces cereÕisiae was also included as a copepod diet. I. galbana, C. muelleri and
Ž .
N. oculata each have a high HUFA content review by Brown et al., 1997 , whereas D. Ž
tertiolecta and yeast contain little or no HUFAs Støttrup and Jensen, 1990; Whyte and .
Nagata, 1990 . The present work was planned to determine the diets that will improve production of
the calanoid copepod G. imparipes at two different temperatures using the criteria of copepod survival, time to maturity, maturation rate, nauplius production and female
prosome length.
2. Materials and method
