Morphological and Biochemical Changes of Sand Dollar Larvae in Response to Variation in Diet and Salinity

<p>Larval growth and development of two sand dollars, <em>Mellita isometra</em> and <em>Dendraster excentricus</em> was investigated by assigning larvae to several single and mixed algal diets, three levels of salinity and salinity-diet combinations in the laboratory. For <em>M. isometra</em>, C<em>haetoceros muelleri</em>, <em>Isochtysis galbana</em> and <em>Dunaliella tertiolectu</em> were used as single algal diets and /. <em>galbana</em> -<em>D. tertiolecta</em>, <em>I. galbana-C. muelleri</em> and <em>C. muelleri - D. tertiolecta</em> as a mixed algal diets. Among the single algal diets, larvae fed <em>Isochrysis galbana</em> were the smallest. They developed smaller rudiments and had the lowest protein content. <em>Mellita</em> larvae fed <em>C. muelleri</em> or the mixed algal diet of /. <em>galbana</em> and <em>D. tertiolecta</em> developed the fastest, had the biggest rudiments, and had the highest protein content. Low salinities favored faster rudiment development. The biggest rudiments were produced by <em>Mellita</em> larvae at 27%o. <em>Mellita</em> larvae maintained at 32%o and fed <em>C. muelleri </em>were significantly longer, wider and had longer posterodorsal arms than larvae in the other two treatments. <em>Dendraster excentric</em>us larvae were fed two single diets: - <em>Dunaliella tertiolecta</em> and <em>Rhodomonas sp</em>. and three mixed diets-<em>D. tertiolecta</em> and <em>Isochrysis galhana</em>, <em>Rhodomonas sp</em>. and /. <em>galbana</em>, and <em>D. tertiolecta</em> and <em>Rhodomonas sp</em>. were used. <em>Rhodomonas sp</em>. had the highest percentage of the long chain PUFAs (polyunsaturated fatty acids), <em>D. tertiolecta</em> had the highest percentage of MUFAs (monounsaturated fatty acids) and <em>I. galbana</em> had the highest percentage of SAFAs (saturated fatty acids). Early larval stages ingested a higher volume of the small alga /. <em>galbana</em> and later larval stages ingested a higher volume of the bigger cells <em>D. tertiolecta</em> and <em>Rhodomonas sp.</em> Larvae fed I. <em>galbana</em> and <em>D. tertiolecta</em> developed faster, had bigger rudiments, the highest protein content and produced more juveniles than the other four diet treatments. Larvae were able to assimilate SAFAs and MUFAs from the algae and synthesize long chain PUFAs.</p> <p>In conclusion, a single algal diet consisting of <em>C. muelleri</em> was just as effective as a mixed algal diet of /, <em>galbana</em> and <em>D. tertiolecta</em> for optimal larval growth and development of the sand dollar <em>M. isometra</em>. <em>I. galbana</em> was ineffective regardless of salinity. Similar to <em>M. isometra</em>, for <em>D. excentricus</em> a mixed algal diet of <em>I.galbana- D. tertiolecta</em> was the best in terms of larval growth and rudiment development.</p>

Name thesis:degree_name

Master of Science

Level thesis:degree_level

Thesis (restricted to Georgia Southern)

Discipline thesis:degree_discipline

Department of Biology

Year dc:date.available

2003

Author dc:creator

• Schiopu, Daniela

Contributors dc:contributor

• Stephen P. Vives
• Alan Harvey

• ETD
• Larval growth
• Sand dollars
• Mellita isometra
• Dendraster excentricus
• Diet
• Salinity
• Algal diets
• Protein content
• Rudiment development
• Biochemistry, Biophysics, and Structural Biology
• Biology

Repository record dc:identifier

https://digitalcommons.georgiasouthern.edu/etd_legacy/363

OAI identifier oai:identifier

oai:digitalcommons.georgiasouthern.edu:etd_legacy-1626