www.elsevier.com/locate/aqua-online

Aquaculture 245 (

Improving gonad colour and somatic index in the European sea

urchin Paracentrotus lividus

Muki Shpigela,*, Susan C. McBrideb, Sharon Marcianoa, Shiri Rona, Ami Ben-Amotzc

aNational Center for Mariculture, Israel Oceanographic and Limnological Research, PO Box 1212, Eilat 88112, IsraelbCalifornia Sea Grant Program, 2 Commercial St., Ste. 4, Eureka, CA 95501

cIsrael Oceanography and Limnological Research Ltd.

Received 5 August 2004; received in revised form 16 November 2004; accepted 22 November 2004

Abstract

One of the major factors influencing marketability of sea urchins is their gonad colour. The effects of a prepared diet, algal

diets, and rotational feeding of these diet treatments on the European sea urchin Paracentrotus lividus were studied to determine

a diet that would provide optimal gonad colour and gonadal somatic index (GSI). P. lividus underwent six diet treatments: Ulva

lactuca and Gracilaria conferta for 12 weeks (UG-12); prepared diet for 10 weeks followed by administration of Ulva and

Gracilaria for 2 weeks (P-10); prepared diet for 8 weeks followed by Ulva and Gracilaria for 4 weeks (P-8); prepared diet for 6

weeks followed by Ulva and Gracilaria for 6 weeks (P-6); prepared diet for 12 weeks (P-12); and Ulva, Gracilaria and

prepared diet for 12 weeks (UGP-12).

The algae diet produced a dark orange colour but a low GSI. The pellet diet produced a good GSI but pale gonad colour. P.

lividus fed the prepared diet for 8 weeks followed by 4 weeks of algal diet produced the optimal combination of desired gonad

colour and GSI.

The dominant carotenoid in the gonads was echinenone, which the sea urchin synthesises from h-carotene. The higher theechinenone level in the gonads, the more intense their colouration. The lack of echinenone found in the gut and its high

accumulation in the gonad, in inverse proportion to the h-carotene profile, indicates bioconversion within the gonad or upon

transfer from the gut to the gonad.

D 2005 Elsevier B.V. All rights reserved.

Keywords: Paracentrotus lividus; Diet; Carotenoids; Gonad colour; GSI

0044-8486/$ - see front matter D 2005 Elsevier B.V. All rights reserved.

doi:10.1016/j.aquaculture.2004.11.043

* Corresponding author. Tel.: +972 8 6361441; fax: +972 8

6375761.

E-mail address: shpigelm@agri.huji.ac.il (M. Shpigel).

1. Introduction

The sea urchin industry is based on the production

of marketable gonads. The quality of the gonads

affects the prices for the product, which range between

US$6 and $200 kg�1 (Unuma, 2002). The most

2005) 101–109

M. Shpigel et al. / Aquaculture 245 (2005) 101–109102

commercially valuable sea urchin gonads are bright

yellow-orange. Carotenoid pigments are the source of

red, orange and yellow colouration and are synthesised

only by plants and microorganisms. Animals are able

to alter these molecules by oxidation.

The colouration in echinoid gonads is derived

primarily from carotenoid pigments, particularly

echinenone which is synthesised from h-carotene by

the sea urchin (Shina et al., 1978; Goodwin, 1984;

Matsuno and Tsushima, 2001). Sea urchins fed

prepared artificial diets often produce gonads that

are large but pale (McBride et al., 1997, 2004;

Lawrence et al., 1997; Barker et al., 1998; Walker

and Lesser, 1998; Pearce et al., 2004), and such

gonads are commercially unacceptable (Lawrence et

al., 1995; Robinson and Colborne, 1998; Watts et al.,

1998; McLaughlin and Kelly, 2001). Natural algal

diets or addition of natural h-carotene product derivedfrom spray-dried algae, Dunaliella salina, resulted in

intensification of gonad colour (McBride et al., 1997,

1999; Robinson et al., 2002; Pearce et al., 2004),

whereas neither synthetic h-carotene nor astaxanthin

improved gonad colour (Goebel and Barker, 1998,

Havardsson and Imsland, 1999). In addition, synthetic

carotenoid pigments are expensive and contribute

significantly to the production cost in salmonid

aquaculture (Torrissen et al., 1990).

The objective of this study was to investigate

whether large gonads of a desirable colour in Para-

centrotus lividus could be produced using a combi-

nation of algal and prepared diets.

2. Materials and methods

The experiments were carried out at the Oceano-

graphic and Limnological Research (IOLR), National

Center for Mariculture (NCM), Eilat, Red Sea, Israel.

Large P. lividus individuals were collected from

rocks in the intertidal zone near Haifa, on the

Mediterranean coast of Israel. The spawning season

for P. lividus in the eastern Mediterranean is

December through March (Shpigel, unpublished

data). Mean initial test diameter and whole live

weight were 40.18F3.84 mm and 29.62F5.79 g,

respectively. P. lividus were stocked in 18 rectan-

gular, 20-l glass aquaria, 6 individuals in each, and

exposed to a natural photoperiod in a covered

outdoor laboratory. All the animals were starved

for 2 weeks prior to the beginning of the feeding

trials. The experiments were conducted between 10

March and 2 June 2000.

The aquaria were supplied with aeration and

unfiltered running seawater. The water flow was kept

at 0.5 l/min and the temperature was 21.8 8CF0.7.

The sea urchins were fed twice a week to satiation.

Uneaten food and faeces were removed by siphoning.

Thorough tank cleaning took place only once a month

to avoid disturbing the animals. Feed portions of algae

were based on wet weight. Excess moisture was

removed by gently squeezing the algae in a mesh net

and blotting on paper towels. The prepared diet was

refrigerated and feed portion was based on fresh

weight. The two algal diets were fed in equal

proportions (50:50), as were the algae and prepared

diet in the UGP-12 treatment. All feeds were present

in aquaria in excess at all times. Uneaten food

removed from aquaria was not weighed and food

consumed was not measured.

The animals underwent six diet treatments: Ulva

lactuca and Gracilaria conferta for 12 weeks (UG-

12); Ulva, Gracilaria, and prepared diet for 12 weeks

(UGP-12); prepared diet for 10 weeks followed by

Ulva and Gracilaria for 2 weeks (P-10); prepared diet

for 8 weeks followed by Ulva and Gracilaria for 4

weeks (P-8); prepared diet for 6 weeks followed by

Ulva and Gracilaria for 6 weeks (P-6); and prepared

diet for 12 weeks (P-12). Three replicates, 6 animals

per replicate, were used.

The algal diets fed to P. lividus consisted of U.

lactuca and G. conferta cultured from fish pond

effluents in the IOLR integrated system (Cohen and

Neori, 1991; Schuenhoff et al., 2003). What we

hereafter refer to as the prepared diet is extruded

moist pellets. Prepared diet ingredients included

wheat gluten, shrimp meal, soybean meal, corn

middlings, fish oil, vitamin and mineral premix. The

proximate analysis of the prepared diet is given in

Table 1. Carotenoid content of the prepared diet is

shown in Table 2.

At the beginning and end of the experiment the

gonad, emptied gut, lantern, and eviscerated test were

weighed to the nearest 0.001 g. Test diameter (TD)

was measured with Verniers calipers (F0.01 mm).

Gonad somatic index (GSI) was calculated as:

GSI=(gonads (g wet)/whole urchin (g wet))*100.

Table 1

Proximate composition (%) of prepared and algal diets fed to

Paracentrotus lividus

Prepared diet Percent (%)

Dry matter 80.82

Crude protein 20.36

Crude fat 3.74

Crude fiber 3.9

Ash 7.72

Carotenoids 1.39

M. Shpigel et al. / Aquaculture 245 (2005) 101–109 103

Colour was assessed by ranking each gonad in

categories from unacceptable to most desirable: dark

orange (DO), pale yellow (PY), bright orange (BO),

yellow-orange (YO), and mango orange (MO),

respectively. Results were compared to other studies

in which DO and PY are considered low quality, BO

and YO are acceptable and MO is excellent

(McLaughlin and Kelly, 2001). Gonad colour was

determined by the same observer in natural daylight.

Total carotenoids and carotenoid composition of

the diets, eight gonads and the digestive system in

each treatment were determined using three-dimen-

sional photo-diode array high-performance liquid

chromatography (HPLC; Ben-Amotz and Levy,

1996). Spectral analysis and auto-scaled chromato-

gram peak heights compared to authentic standards

were used to determine carotenoid concentration by

percentage. Spectral diagrams were used with extinc-

tion coefficients (Bauernfeind, 1981) to identify

carotenoids in the diets, gonads and digestive system.

Total carotene levels and carotenoid composition in

the gonads were measured in all treatments; these

parameters in the gut were measured only for UG-12

and P-10 diets. Total carotenes are given as Ag g�1 per

wet weight of the respective organ (gonad or gut).

Carotenoid composition is given as a percentage of

the organ wet weight (WW).

2.1. Statistics

Whole weight, test diameter, and gonad index were

compared using one-way ANOVA for aquarium

Table 2

Carotenoid content of prepared diet (mg/kg)

Diet Total carotenoid h-carotene h-c

Prepared diet 13.86 5.31 0.4

means. For all ANOVA, the df are 6, 14, and 20

between treatments, residual and total, respectively.

The data showed homogeneity of variance (Cochran’s

C-test) and were normally distributed (Kolmogorov–

Smirnoff test with Lilliefors modification). Significant

differences were compared using the Tukey’s test.

3. Results

3.1. Growth

No significant differences were found between the

initial sample and diet treatments for whole live

weight and test diameter after 12 weeks; F=1.120,

p=0.400, F=0.161, P=0.093, respectively (Table 3).

Gonad somatic index (GSI) of P. lividus from the

initial stage and UG-12 treatment was significantly

lower compared to all other treatments (F=52.643,

pb0.001). GSI in the P-12 and P-10 diets were about

22% of the wet weight (WW) and were also

significantly greater than P. lividus gonads in P-6

and UGP-12 treatments. There were no significant

differences in the GSI between P-12, P-10, and P-8

treatments (Fig. 1). The GSI attained by P. lividus

from P-6 (14.4%) and UGP-12 (16.6%) diets are

commercially acceptable for Strongylocentrotus fran-

ciscanus (McBride et al., 1997).

3.2. Pigments

Total carotenoids in the gonads ranged between 17

and 60 Ag g�1 WW. Total carotenoids in UG-12 diet

were significantly higher than in all other diets.

Carotenoid levels in P-8, P-10 and UGP-12 diets

were similar. P-12 and P-10 diets showed the lowest

levels of carotenoids (Fig. 2).

In the gut, total carotenoid levels in P-12 and P-10

diets were similar to those of the gonads and were

approximately 15 Ag g�1 WW. In the rest of the diets,

carotenoid levels were significantly ( F=43.24,

pb0.01) higher than those of the gonads, ranging

ryptoxanthin Lutein Zeaxanthin Other

9 2.17 2.06 3.83

Table 3

Whole live weight (WW) and test diameter (TD) of Paracentrotus lividus from the initial sample and six diet treatments

Initial sample UGP-12 P-12 P-10 P-8 P-6 UG-12

WW (g) 29.62F5.79 32.52F1.42 33.98F1.86 34.78F2.33 34.33F0.86 33.67F3.77 31.96F0.36

TD (mm) 40.18F3.08 39.78F0.45 40.87F1.96 40.16F0.63 39.88F1.46 40.52F1.02 40.18F0.84

M. Shpigel et al. / Aquaculture 245 (2005) 101–109104

between 108 Ag g�1 WW in the P-6 diet and 31 Agg�1 WW in the UGP diet (Fig. 2).

In the gonads echinenone was the dominant

carotenoid, ranging between 75% and 78% of the

total carotenoids in all the diets; xanthophyll levels

increased from 2.5% in P-6 diet to 13% in P-10 diets

(Table 4a); and a-and h-carotene ranged between 3%

and 8% of the total carotenoids.

In UG-12 diet, echinenone levels in the gut were

lower (3.1%) compared to the gonads. Fucoxanthin

(31.6%) and h-carotene (37.3%) were the dominant

pigments. The amount of h-carotene was lower in the

P-10 diet than the UG-12 diet. (Table 4b).

The total chlorophyll content (a and b) in Ulva and

Gracilaria was 10 mg g�1 and 5 mg g�1 DW,

respectively. The total carotenoid content in Ulva and

Gracilaria was 2 mg g�1 and 0.5 mg g�1 DW,

respectively.

Pigment composition in Ulva and Gracilaria is

described in Table 5. Ulva contains a high proportion

0

5

10

15

20

25

Initial UGP-12 P-12 P

mea

n go

nad

inde

x (%

)

b

b, c

aa

Fig. 1. Wet gonad index for Paracentrotus lividus from six diet treatment

letter are not significantly different.

of chlorophyll a and b, while Gracilaria contains

chlorophyll a and d. Both species contain a small

proportion of h-carotene (2.88–3.95%).

3.3. Colour

The most intense colouration of gonads (42.8% of

DO and 29% of BO) was observed in the sea urchins

fed the UG-12 diet (Fig. 3). The palest colour (78%

PY and 22% YO) was seen in the P-12 diet. The sea

urchins given the UG diet produced only DO-, BO-,

and MO-coloured gonads, while those receiving the

prepared diet appeared to have only YO and PY

gonads. The initial sample of P. lividus gonads

showed all colours except PY, with the greatest

number of gonads falling in the DO and MO

categories. At the end of the study, all treatments

except P-12 had 23 to 28% of individuals with MO

gonads. MO colour was found in the P-10 treatment.

Bright orange, mango orange, and yellow orange, the

-10 P-8 P-6 UG-12

, c

a, c

b, c

b

s and an initial sample (n=3, meanFS.D.). Columns with the same

To

tal C

aro

ten

oid

s (µµ

g/g

-1 w

w)

0

20

40

60

80

100

120

140

P-10 P-8 P-6 U/G UGPDiet

guts gonads

P-12

Fig. 2. Total carotenoid levels of guts and gonads for Paracentrotus lividus (n=18, meanFS.D.).

M. Shpigel et al. / Aquaculture 245 (2005) 101–109 105

three acceptable gonad colours, were found in all

treatments except P-12. UGP was the only treatment

where all urchins had a gonad colour scoring

dacceptableT or above.

4. Discussion

The results of the present study indicate that the

prepared diet is very effective in increasing gonad

mass while algae can be used to improve gonad

quality and colour. For example: after conditioning

the urchins for 12 weeks with prepared diet, GSI

reached a satisfactory level (23%); however, although

pigments are included in the prepared diet, the colour

was too pale (78% were PY) to be acceptable to the

market. On the other hand, animals fed for 12 weeks

with U. lactuca and G. conferta showed an intense

orange colour (42.8% DO) of the gonads, but their

GSI was relatively low (8%) and similar to the initial

level. It was encouraging that the effects of improved

gonad color were seen after only two weeks of feeding

Table 4a

Carotenoid distribution (% of total) in sea urchin gonads

Diet P-10 P-8 P-6 UG-12

Xanthophylls 13.0 12.0 2.5 7.6

Isocrypotoxanthin 0.4 2.3 3.0 3.4

Echinenone 75.2 72.5 78.2 78.2

a-carotene 6.0 6.3 6.5 3.1

h-carotene 5.4 4.2 9.8 7.7

on U. lactuca and G. conferta in the P-10 treatment.

This relatively simple change from prepared diet to

algae may have applications in commercial aquacul-

ture of sea urchins. The relatively large GSI of P.

lividus fed UGP-12 (16.6%) suggests that the sea

urchins consumed the prepared feed along with the

algal diets, resulting in good gonad color and

production. Rotational feeding may be more easily

controlled by aquaculturists than feeding all three

diets in a production facility. In this study and others,

sea urchins increase in gonad mass by about 1% per

week when fed prepared diet alone (McBride et al.,

1997, 1999). Lack of whole animal weight change

during this study even though gonad mass did

increase is due to the similar specific gravity of the

sea urchin pervisceral fluid to that of the gonads

(Lawrence, 1975).

Overall results in this study show that the best

compromise between colour and GSI was obtained

with the P-8 diet, in which GSI was 18.2% and 78% of

the gonads were of good colour, including 28% of the

ideal MO. This suggests that in sea urchin culture,

Table 4b

Carotenoid distribution (% of total) in sea urchin guts

Diet P-10 UG

Fucoxanthin 36.7 31.6

Isocryptoxanthin 16.3 16.2

Echinenone 6.7 3.1

a-carotene 11.3 11.8

h-carotene 29.0 37.3

Table 5

Pigment distribution (% of the total pigment) in Ulva lactuca and

Gracilaria conferta

Pigment distribution

(% of total pigments)

Ulva Gracilaria

Chlorophyll a 44.8 50.01

Chlorophyll b 39.75 0

Chlorophyll d 0 38.63

a-carotene 1.14 (17%) 3.69 (17%)

h-carotene 3.95 (43%) 2.88 (38%)

Phaeophytins 8.78 2.69

Xanthophylls 2.72 (40%) 1.10 (14%)

The numbers in parentheses are percentages of the total carotene.

M. Shpigel et al. / Aquaculture 245 (2005) 101–109106

addition of macroalgae to the diet four weeks before

harvest can best provide the desired balance between

gonad colour and GSI. Many aquaculturists prefer to

use prepared feed rather than macroalgae due to the

expense and logistics of acquiring the latter, together

with fluctuations in their nutritional value and health

(Pearce et al., 2003). However, integrated polyculture

systems often incorporate these algae as biofilters

(Shpigel et al., 1993, Neori et al., 2003, Schuenhoff et

al., 2003) and therefore have a steady supply, as well as

control over their nutritional value and sanitary aspects.

0%

20%

40%

60%

80%

100%

Initial UGP-12 P-12 P-

dark orange pale yellow bright orang

Fig. 3. Gonad colour for Paracentrotus lividus fed six experimental diets (n

gonads in each colour category. Mango orange is most desirable; bright oran

unacceptable.

Our results are consistent with those obtained in

studies with other species, where sea urchins fed

prepared diets had significantly higher GSI than

animals fed on algae alone (Lawrence et al., 1997;

Pearce et al., 2003), but the pale colouration of their

gonads made the animals commercially unacceptable

(Lawrence et al., 1995; Robinson and Colborne, 1998;

Watts et al., 1998; McLaughlin and Kelly, 2001).

Conversely, Pearce et al. (2003) found that gonad

colour of Strongylocentrotus droebachiensis fed pre-

pared diet or kelp diet did not differ significantly

between the two diets. However, these authors’

prepared diet contained 0.2% synthetic h-carotene,and 22.8% macroalgal meal. It seems that the quality

colour obtained from their diet came mainly from the

macroalgal meal and not from the h-carotene. Studieshave shown that addition of synthetic h-carotene or

astaxanthin did not improve gonad colour (Goebel and

Barker, 1998, Havardsson and Imsland, 1999), while

algal diets and h-carotene derived from the alga D.

salina did contribute colour (McBride et al., 1997,

1999, 2004; Robinson et al., 2002; Pearce et al., 2004).

Gonad colouration was also noted when using vegeta-

ble preparations of carrot and paprika, which have a

10 P-8 P-6 UG-12

e yellow orange mango orange

=18/treatment) and the initial sample (n=20). Values are the percent of

ge and yellow orange are acceptable; dark orange and pale yellow are

10% 28% 40% 70%

0

5

10

15

20

25

30

35

40

45

50

P-8 P-6 U/G P-10

Ech

inen

one

leve

l (µ

g/ g-1

WW

)

Diet

Fig. 4. Echinonene levels in the gonads using different diets (the values inside the arrow represent the percent of DO and BO, the dark colours)

in the samples.

M. Shpigel et al. / Aquaculture 245 (2005) 101–109 107

high natural carotenoid content. Robinson et al. (2002)

achieved the most effective intensification of sea urchin

gonad colour with the addition of spray dried alga D.

salina at a concentration of 250 mg h-carotene/kg dry

weight of feed. It is not yet clear why naturalh-caroteneoutperformed the synthetic all-trans h-carotene, or

whether gonad colouration is related to bioavailability,

bioabsorption, or bioconversion of the added pigments

in the gut and in the gonad.

In the present study, the pigment content of the

marine algae used is composed mainly of chlorophylls

β-ca

rote

ne le

vels

(µµg

/g-1

WW

)

37.3

3.1

0

5

10

15

20

25

30

35

40

Gut

Betacarotene

Fig. 5. Echinenone (E) and h-carotene (x) levels in sea urchin guts and gocomprised by each.

and their degradation products, phaeophytins, xantho-

phylls and hydrocarbon carotenoids. Our results

showed that the natural source of carotenoids derived

from seaweeds was more effective in achieving good

colouration than comparable concentrations of syn-

thetic carotenoids supplied in the prepared diet.

The intense gonad colouration is attributed to high

bioavailability of the algal pigments in sea urchin

gonads. While only present at low levels in the gut,

echinenone was the predominant pigment in the

gonad, comprising over 75% of total carotenoid

Echinenone levels (µg/g

-1 WW

)

7.7

75.0

Gonads0

10

20

30

40

50

60

70

80Echinonene

nads. Numbers inside graph represent percentage of total carotenoids

M. Shpigel et al. / Aquaculture 245 (2005) 101–109108

content. A positive relationship between echinenone

levels and gonad colour was found in this study (Fig.

4), suggesting that echinenone is the major factor

determining its intensity.

Echinenone has been identified as being the

dominant carotenoid in most sea urchin gonads

(Griffiths, 1966; Griffiths and Perrot, 1976; Tsushima

and Matsuno, 1990), and h-carotene has been shown

to be the precursor for the metabolic process leading

to echinenone production (Tsushima et al., 1993). The

same pattern was found in our study. The lack of

echinenone in the gut and its high accumulation in the

gonad, in exactly inverse proportion to the h-caroteneprofile, indicates bioconversion within the gonad or

possibly during assimilation (Fig. 5).

It is not clear where the bioconversion of h-carotene to echinenone takes place. Griffiths and

Perrot (1976) stated that, in P. lividus, this process

takes place exclusively in the gonads. However, due

to high levels of echinenone and its precursor,

isocryptoxanthin, found in the gut, Tsushima and

Matsuno (1990) and Tsushima et al. (1995) postulate

that this is where the synthesis takes place. In our

study as well, isocryptoxanthin levels in the gut

were higher than in the gonad, inverse to echinenone

levels, suggesting that at least part of the synthesis

occurs in the gut. Similar results were found by

Plank et al. (2002), who observed that several

pathways exist to metabolise dietary carotenoids in

Lytechinus variegatus, including nutritive phago-

cytes in the gonads that store nutrients used in

gametogenesis.

Because echinenone comprises as much as 83% of

the total carotenoids in the various echinoid gonads

studied, Plank et al. (2002) suggest that this is the

terminal carotenoid in sea urchin organs and that these

high levels indicate its importance for the develop-

ment of gametes, eggs, and embryos.

Acknowledgements

This research was funded by the Texas–Israeli

Exchange Fund Board, grant no. 845-4782, and by the

Israeli Ministry of Agriculture, grant no. 894-0125-02

to MS, and a grant from the National Sea Grant

College Program, National Oceanographic and

Atmospheric Administration, U.S. Department of

Commerce, under Grant NOAA NA06RG0142, proj-

ect number A/EA-1, through the California Sea Grant

College System to SM.

Thanks to Prof. John Lawrence and Dr. Angelo

Colorni for helpful comments; and to Mikhal Ben-

Shaprut for help in editing.

References

Barker, M.F., Keogbh, J.A., Lawrence, J.M., Lawrence, A.L., 1998.

Feeding rate, absorption efficiencies, growth, and enhancement

of gonad production in the New Zealand sea urchin Evechinus

chloroticus Valenciennes (Echinoidea: Echinometridae) fed

prepared and natural diets. J. Shellfish Res. 17, 1583–1590.

Bauernfeind, J.C., 1981. In: Bauernfeind, J.C. (Ed.), Carotenoids as

Colorants and Vitamin A Precursors. Academic Press, NewYork.

Ben-Amotz, A., Levy, I., 1996. Bioavailability of a natural isomer

mixture compared with synthetic all-trans h-carotene in human

serum. Am. J. Clin. Nutr. 63, 729–734.

Cohen, I., Neori, A., 1991. Ulva lactuca biofilters for marine

fishpond effluent: I. Ammonia uptake kinetics and nitrogen

content. Bot. Mar. 34, 475–482.

Goebel, N., Barker, M.F., 1998. Artificial diets supplemented

with carotenoid pigments as feeds for sea urchins. In: Mooi,

R., Telford, M. (Eds.), Echinoderms. Balkema, San Francisco,

pp. 667–672.

Goodwin, T.W., 1984. Animals, (2nd ed.). The Biochemistry of the

Carotenoids, vol. II. Chapman & Hall, New York.

Griffiths, M., 1966. The carotenoids of the eggs and embryos of

the sea urchin Strongylocentrotus purpuratus. Dev. Biol. 13,

296–309.

Griffiths, M., Perrot, P., 1976. Seasonal changes in the carotenoids

of the sea urchin Strongylocentrotus droebachiensis. Comp.

Biochem. Physiol. 55, 435–441.

Havardsson, B., Imsland, A., 1999. The effect of Astaxanthin in

feed and environmental temperature on carotenoid concentration

in the gonads of the green sea urchin Strongylocentrotus

droebachiensis Muller. J. World Aquac. Soc. 30 (2), 208–218.

Lawrence, J.M., 1975. The relationship between echinoids and

marine plants. Ocean. Mar. Biol. Ann. Rev. 13, 213–286.

Lawrence, J.M., Olave, S., Otaiza, R., Lawrence, A.L., Bustos, E.,

1995. A comparison of gonad production in Loxechinus albus

(Echinodermata: Echinoidea) fed algae and prepared feeds. Am.

Zool. 35, 109A.

Lawrence, J.M., Olave, S., Otaiza, R., Lawrence, A.L., Bustos, E.,

1997. Enhancement of gonad production in the sea urchin

Loxechinus albus in Chile fed extruded feeds. J. World Aquac.

Soc. 28, 91–96.

Matsuno, T., Tsushima, T., 2001. Carotenoids in sea urchins. In:

Lawrence, J.M. (Ed.), Edible sea urchins: Biology and Ecology.

Amsterdam, Elsevier, pp. 115–138.

McBride, S.C., Pinnix, W.D., Lawrence, J.M., Lawrence, A.L.,

Mulligan, T.M., 1997. The effect of temperature on production

of gonads by the sea urchin Strongylocentrotus franciscanus fed

natural and prepared diets. J. World Aquac. Soc. 28, 357–365.

M. Shpigel et al. / Aquaculture 245 (2005) 101–109 109

McBride, S.C., Lawrence, J.M., Lawrence, A.L., Mulligan, T.J.,

1999. Ingestion, absorption, and gonad production of adult

Strongylocentrotus franciscanus fed different rations of a

prepared diet. J. World Aquac. Soc. 30 (3), 364–370.

McBride, S.C., Price, R.J., Tom, P.D., Lawrence, J.M., Lawrence,

A.D., 2004. Comparison of gonad quality factors: color,

hardness and resilience, of Strongylocentrotus franciscanus

between sea urchins fed prepared feed or algal diets and sea

urchins harvested from the Northern California fishery. Aqua-

culture 233, 405–422.

McLaughlin, G., Kelly, M.S., 2001. Effect of artificial diets

containing carotenoid-rich microalgae on gonad growth and

colour in the sea urchin Psammechinus miliaris (Gmelin).

J. Shellfish Res. 20 (1), 377–382.

Neori, A., Msuya, F.E., Shauli, L., Schuenhoff, A., Lupatsch, I.,

Shpigel, M., 2003. A novel three-state Ulva lactuca biofilter

design for integrated mariculture: fast and efficient ammonia

uptake rates and high yields of protein-rich biomass. J. Appl.

Phycol. 15, 543–553.

Pearce, C.M., Daggett, T.L., Robinson, S.M.C., 2003. Effects of

starch type, macroalgal meal source, and B-carotene on gonad

yield and quality of the green sea urchin, Strongylocentrotus

droebachinensis (Muller), fed prepared diets. J. Shellfish Res.

22 (1), 505–519.

Pearce, C.M., Daggett, T.L., Robinson, S.M.C., 2004. Effect of

urchin size and diet on gonad yield and quality in the green sea

urchin (Strongylocentrotus droebachiensis). Aquaculture 233,

337–367.

Plank, L.R., Lawrence, J.M., Lawrence, A.L., Olvera, R., 2002. The

effect of dietary carotenoids on gonad production and carotenoid

profiles in the sea urchin Lytechinus variegatus. J. World

Aquac. Soc. 33 (2), 127–137.

Robinson, S.M.C., Colborne, L., 1998. Roe enhancement trials of

the green sea urchin using an artificial food source. In: Moo, R.,

Telford, M. (Eds.), Proceedings of the 9th International

Echinoderm Conference, San Francisco, 1996. Balkema, Rot-

terdam, pp. 803.

Robinson, S.M.C., Castell, J.S., Kennedy, E.J., 2002. Devel-

oping suitable colour in the gonads of cultured green sea

urchins (Strongylocentrotus droebachiensis). Aquaculture 206,

289–303.

Schuenhoff, A., Shpigel, M., Lupatsch, I., Ashkenazi, A., Msuya,

F.E., Neori, A., 2003. A semi-recirculating, integrated system for

the culture of fish and seaweed. Aquaculture 221, 167–181.

Shina, A., Gross, J., Lifshitz, A., 1978. Carotenoids of the

invertebrates of the Red Sea (Eilat Shore): II. Carotenoid

pigments in the gonads of the sea urchin Tripneustes gratilla

(Echinodermata). Comp. Biochem. Physiol. 61B, 123–128.

Shpigel, M., Neori, A., Popper, D.M., Gordin, H., 1993. A proposed

model for benvironmentally cleanQ land-based culture of fish,

bivalves and seaweeds. Aquaculture 117, 115–128.

Torrissen, O.J., Hardy, R.W., Shearer, K.D., Scott, T.M., Stone,

F.E., 1990. Effects of dietary canthaxanthin level and lipid

level on apparent digestibility coefficients for canthaxanthin

in rainbow trout (Oncorhynchus mykiss). Aquaculture 88,

351–362.

Tsushima, M., Matsuno, T., 1990. Comparative biochemical studies

of carotenoids in sea-urchins—I. Comp. Biochem. Physiol. 96B,

801–810.

Tsushima, M., Kawakami, T., Matsuno, T., 1993. Metabolism of

carotenoids in sea-urchin Pseudocentrotus depressus. Comp.

Biochem. Physiol. 106B, 737–741.

Tsushima, M., Byrne, M., Amemiya, S., Matsuno, T., 1995.

Comparative biochemical studies of carotenoids in sea urchins:

III. Relationship between developmental mode and carotenoids

in the Australian echinoids Heliocidaris erythrogramma and H.

tuberculata and a comparison with Japanese species. Comp.

Biochem. Physiol. 110B, 719–723.

Unuma, T., 2002. Gonadal growth and its relationship to aqua-

culture in sea urchins. In: Yukio, Y., Matranga, V., Smolenicka,

Z. (Eds.), The Sea Urchin: From Basic Biology to Aquaculture.

A.A. Balkema Publishers, The Netherlands, pp. 115–128.

Walker, C.W., Lesser, M.P., 1998. Manipulation of food and

photoperiod promotes out-of-season gametogenesis in the green

sea urchin Strongylocentrotus droebachiensis: implications for

aquaculture. Mar. Biol. 132, 663–676.

Watts, S.A., Boettger, S.A., McClintock, J.B., Lawrence, J.M.,

1998. Gonad production in the sea urchin Lytechinus

variegatus (Lamarck) fed prepared diets. J. Shellfish Res. 17

(5), 1591–1595.