autofluorescence

Hermodice carunculata the bearded fireworm is abundant in Bonaire‘s coral reefs. The corallivorous fireworm is a voracious eater, and a generalist predator. H. carunculata’s foraging behaviors play a role in coral reef community structure and building. This study looked at the abundance of the bearded fireworm in two environments, coral reefs and sand flats, during dusk and night hours. Within these two substrates size, abundance, and fluorescent color morphologies of the fireworms were studied. Sizes were separated into four length categories: 9 cm. Due to the active nature of fireworms and sampling at night, BlueStar flashlights and yellow barrier filters were used to locate the fireworms in the dark. Field surveys were conducted using 10 m transects and a t-bar to estimate abundance in both environments. Wire box traps were also placed along the coral reef and sand flats to estimate abundance of fireworms in the area. H. carunculata were found to be less abundant on coral reefs at dusk than at night. Furthermore, fireworms in the size class >9 cm were only found on coral reefs, indicating an ontogenetic shift in habitat and size. An ontogenetic shift was also found in the fluorescent color morphologies. Green fluorescence was most abundant in the 0-6 cm size range, and completely absent in the >9 cm size class. The green body with orange bands was an intermediate fluorescent pattern found predominantly in 3-9 cm size range. The orange body with orange bands coloration was found in the largest size class, possibly being the terminal fluorescent phase.

This student research was retrieved from Physis: Journal of Marine Science XIII (Spring 2013)19: 1-9 from CIEE Bonaire.

Abstract

An integrated suite of imaging techniques has been applied to determine the three-dimensional (3D) morphology and cellular structure of polyp tissues comprising the Caribbean reef building corals Montastraeaannularis and M. faveolata. These approaches include fluorescence microscopy (FM), serial block face imaging (SBFI), and two-photon confocal laser scanning microscopy (TPLSM). SBFI provides deep tissue imaging after physical sectioning; it details the tissue surface texture and 3D visualization to tissue depths of more than 2 mm. Complementary FM and TPLSM yield ultra-high resolution images of tissue cellular structure. Results have: (1) identified previously unreported lobate tissue morphologies on the outer wall of individual coral polyps and (2) created the first surface maps of the 3D distribution and tissue density of chromatophores and algae-like dinoflagellate zooxanthellae endosymbionts. Spectral absorption peaks of 500 nm and 675 nm, respectively, suggest that M. annularis and M. faveolata contain similar types of chlorophyll and chromatophores. However, M. annularis and M. faveolata exhibit significant differences in the tissue density and 3D distribution of these key cellular components. This study focusing on imaging methods indicates that SBFI is extremely useful for analysis of large mm-scale samples of decalcified coral tissues. Complimentary FM and TPLSM reveal subtle submillimeter scale changes in cellular distribution and density in nondecalcified coral tissue samples. The TPLSM technique affords: (1) minimally invasive sample preparation, (2) superior optical sectioning ability, and (3) minimal light absorption and scattering, while still permitting deep tissue imaging.