- Title
- The effect of fresh seaweed and a formulated diet supplemented with seaweed on the growth and gonad quality of the collector sea urchin, Tripneustes gratilla under farm conditions
- Creator
- Onomu , Abigail John
- Subject
- Marine algae Algae
- Date
- 2019
- Type
- Thesis
- Type
- Masters
- Type
- MSc
- Identifier
- http://hdl.handle.net/10353/14682
- Identifier
- vital:40044
- Description
- This study investigates the effect of two fresh seaweeds, a formulated diet and different feeding regimes on the growth (weight, diameter and height) and gonad quality (gonadosomatic index, colour, texture, firmness and gonad maturity) of the collector sea urchin, Tripneustes gratilla under farm conditions for eighteen weeks. The gonad enhancement study was divided into two sections. The first section investigated the effect of feeds on the somatic growth and gonad quality for 12 weeks. The feeds investigated during this phase of the study were fresh Ulva (U); a 50:50 mixture of fresh Ulva and Gracilaria (UG); fresh Gracilaria (G) and a formulated diet, which contained 200g of dried Ulva per kg (designated as 20U). The second section or phase of this study started for a period of 6 weeks and investigated the effect of a change of diet on urchins previously fed the various feeds from section 1. The feeding regimes used were (U-20U) i.e urchins previously fed with Ulva were subsequently fed 20U diet, similarly, (UG-20U); (G-20U) and (20U- 20U). For the first section of the experiment, no differences were observed in the growth (weight, diameter and height) of urchins fed both fresh diets and the formulated diet. However, urchins fed the formulated diet produced gonad weight of 50.72 ± 5.4g which was significantly higher (P<0.001) than those fed fresh diets. The gonads of urchins fed the Gracilaria diet were significantly darker (P= 0.023) in colour compared with those examined from urchins fed the formulated diet, but were not significantly different from any of the other fresh diets tested (Ulva and Ulva mixed with Gracilaria). Gonad from each of the feed treatments were similar in terms of the redness (a*) and yellowness (b*) as well as the texture and firmness. The gonad maturities of urchins fed the various diets were not significantly different from each other. By the end of the second section/phase of the study (6 week period following the diet change), somatic growth (weight, height and diameter) of urchins in all treatment groups did not differ significantly from each other (ANOVA, P= 0.784; P= 0.988; P= 0.28 respectively). Gonad weight of urchins in treatment groups UG-20U and G-20U became similar to those fed the 20U diet at the end of the trial (week18). However, the gonad weight of urchins in the 20U treatment group remained significantly greater than urchins in the U-20U group at the end of the trial (Kruskal-Wallis ANOVA, P= 0.002). Gonad colour of urchins in the G-20U treatment became significantly lighter (ANOVA, P= 0.029) than those in the U-20U group after the change of diet. However, gonad lightness (L*) of urchins in treatment groups U-20U and G–20U did not differ significantly from those in the UG-20U and 20U treatment groups. All feed regimes were similar in terms of the gonad‟s redness (a*) and yellowness (b*), texture and firmness as well as gonad maturity at the end of the trial. This gonad enhancement study on wild collected adult T. gratilla has shown that somatic growth (urchin weight, test diameter and height) does not differ between the dietary treatments (fresh seaweeds and a formulated diet) tested in this study. The formulated feed (20U diet) does however enhance gonad growth of T. gratilla under farm conditions, supporting previous laboratory trials conducted on this species fed similar diets, indicating that sea urchins gonad enhancement can be cultured under farm conditions in South Africa.
- Format
- 127 leaves
- Format
- Publisher
- University of Fort Hare
- Publisher
- Faculty of Science and Agriculture
- Language
- English
- Rights
- University of Fort Hare
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UFH Department of Zoology & Entomology
| Thumbnail | File | Description | Size | Format | |||
|---|---|---|---|---|---|---|---|
| View Details | SOURCE1 | Onomu, AJ - MSc Dissertation (Zoology) 2019 - Final post-examination version.pdf | 1 MB | Adobe Acrobat PDF | View Details |