Advisory Committee Chair
Stephen A Watts
Advisory Committee Members
Andy Gannon
John Lawrence
James McClintock
Thane Wibbels
Document Type
Dissertation
Date of Award
2008
Degree Name by School
Doctor of Philosophy (PhD) College of Arts and Sciences
Abstract
The range of the regular echinoid Lytechinus variegatus extends from the Carolinas along the US Atlantic coast to Brazil. To our knowledge, the present study is the northernmost study to examine histology of the reproductive cycle of Lytechinus variegatus. From April 2001 to September 2003, at intervals of about 4-6 weeks, L. variegatus with an average diameter of 45 mm were collected at Eagle Harbor in St. Joseph’s Bay, Florida.. A staging system for gamete development and maturation based on histology of the gonad was devised for female and male L. variegatus. Histology indicated a period of nutrient storage and limited gametogenic activity in the fall and winter preceded spring gamete production and maturation. Histometrics indicated that gametes comprise a maximum percentage within gonad acini in the spring and again in the late summer, indicating a biannual cycle. Correlation coefficients with gonad index were higher for relative nutrient storage capacity than for relative reproductive potential, indicating that the gonad index is a better indicator of nutrient storage than reproductive state. Biochemical analysis of gonad tissue indicated that stored lipids were not related to changes in gonad size or cell populations. The negative correlation of percent carbohydrates and percent gametes indicated that carbohydrates were a primary energy iii source during gametogenesis. Comparisons of proximate component production and gonad index indicated that gonad index is a better indicator of nutrient storage than of gamete production. Nutrient reserves were higher in the spring and may increase the reproductive success of L. variegatus that spawn in the spring compared to those that spawn in the summer. Cyclical changes in the storage of proximate components in the gonad may represent an innate response in relation to reproductive stage of an individual, the control of which (abiotic vs. biotic) has not been determined. The results for the 18 and 28ºC and the spring and summer treatments suggest that eggs developing at typical spring and summer temperatures acclimated (and acclimatized) to their respective temperatures. In addition, results from the spring and summer treatments indicate that eggs developing at summer temperatures are generally less likely to be viable than eggs developing at spring temperatures.
Recommended Citation
Cunningham, Adele, "The Reproductive Cycle Of Lytechinus Variegatus (Echinodermata: Echinoidea) From The Florida Panhandle" (2008). All ETDs from UAB. 3687.
https://digitalcommons.library.uab.edu/etd-collection/3687