| Abstract | Istraživanje ovog diplomskog rada je provedeno s ciljem određivanja utjecaja različitih mikroalgalnih hranidbenih režima na rast, kompetenciju i metamorfozu ličinki hridinskog ježinca, Paracentrotus lividus. Za potrebe istraživanja prikupljene jedinke hridinskog ježinca iz dubrovačkog akvatorija, zaljeva Gruž, injektirane su 1M otopinom KCL-a, a jajne stanice i spermatozoidi su transportirani u biološki laboratorij Sveučilišta u Dubrovniku, gdje je obavljena oplodnja i pokus. Dobivene ličinke su postavljene na četiri hranidbena režima gdje je početna koncentracija ličinki po ml bila jednaka u svim pokusnim posudama; Isochrysis galbana (H1), Chaetoceros gracilis (H2), Tetraselmis suecica (H3) u monokulturi, dok se hrana za četvrtu skupinu sastojala od mješavine triju mikroalgi (H4). Istraživanje je trajalo 21 dan, ličinke su hranjene svakodnevno, provjeravana im je kompetencija, a zabilježeni razvojni stadiji su fotografirani i pohranjeni na računalu za daljnju morfometrijsku analizu. Na samom početku pokusa (48h), u svim skupinama su zabilježeni mortaliteti (10-50%). H1 skupina je jedina koja je uspješno prošla kroz preobrazbu, dok je H2 skupina prva u kojoj je zabilježen totalni mortalitet (9 DNO – dan nakon oplodnje) i prekid uzgoja deveti dan. U skupini H3 zabilježeno je najveće preživljavanje (od početka eksperimenta 14 DNO) te je gustoća jedinka po ml bila (20/ml) znatno veća od ostalih skupina tijekom pokusnog razdoblja. U režimu H3, nakon razvoja 4. nožice zaustavljene su razvojne promjene u ontogenezi, odnosno sve do kraja trajanja istraživanja, pluteusi su ostali „zarobljeni“ u stadiju s 4 nožice. U hranidbenom režimu H4 dio jedinka je zaostao u razvojnom stadiju 4 nožice (15 DNO, 20%), a dio je pokazivao deformiranosti u razvoju (70%). Ovim istraživanjem se pokazala prikladnost vrste, Isochrysis galbana, kao hrane za rane razvojne stadije hridinskog ježinca premda je važno uzeti u obzir preživljavanje postličinki i mlađi, a kako bi se utvrdila učinkovitost hranidbenih tretmana. Stoga, potrebna su daljnja istraživanja na kvaliteti hrane kao i podloge za preobražaj.. |
| Abstract (english) | The current study was carried out to investigate the effect of different algal diets on growth, competence and metamorphosis of common sea urchin, Paracentrotus lividus larvae. For the purposes of the study, urchin samples were taken from Gruž Bay and injected with 1M KCL to induced spawning. Collected eggs and sperm were transported to the laboratory of Dubrovnik University where the experiment was carried out. The echinopluteus larvae were fed four microalgal diets consisting of: Isochrysis galbana (H1), Chaetoceros gracilis (H2), Tetraselmis suecica (H3) and mixture of three algal species at equal ratio (H4). The study lasted for 21 days, while algal diets were provided daily and larvae were checked for competence. All stages of development were photographed and saved for later analysis. At the beginning of the experiment (48h) mortality was recorded in all four groups (10-50%). Sample H1 was the only one that went through metamorphosis, while in the sample H2 total mortality was recorded (9 DPF- days post fertilization) therefore, the experiment was terminated for sample H2. The sample H3 showed the highest survival rates (from the beginning of the experiment to 14 DPF), where the density of larvae (20/m) was significantly higher than recorded in other samples, and such was the case until the end of the experiment. The sampled H3 showed a great deal of abnormalities while the „normal“ pluteus were arrested in 4-arm stage until the end of the study. In the sample H4 a part of the larvae were arrested in 4-arm stage (15 DPF, 20%), at the same time a great deal of abnormalities were recorded (70%). The present study suggest that Isochrysis galbana diet succeeded to support P. lividus larval development to competence and metamorphosis, although it is necessary to further investigate the survival rate of postlarvae and juveniles. Further research is needed on diet quality and suitable substrate for metamorphosis. |
