Meeting Abstract

P3.135  Sunday, Jan. 6  Preliminary Anatomical Comparison of Choroid Rete Structure Between Diurnal and Nocturnal Reef Fishes TOUSIGNANT, K.A.S.*; SHERMAN, R.L.; Nova Southeastern University; Nova Southeastern University kshade@nova.edu

The choroid rete is a richly vascularized network of capillaries within the teleost eye that provides oxygen to the avascular retina. Parallel arrangement of capillaries within the rete allows for efficient countercurrent exchange of gases and materials. Previous studies have suggested that more visually-dependent fish exhibit increased development of the choroid rete; however, no comparisons between diurnal and nocturnal reef fish rete structure have been made to date. Vascular corrosion casting techniques were applied to two nocturnal specimens (20cm Lutjanus griseus and 20.9cm Lutjanus apodus) and two diurnal specimens (34cm Carangoides ruber and 21.1 cm Lagodon rhomboides) captured on reef patches off southeastern Florida. Resulting choroid rete casts were photographed via scanning electron microscopy to examine and measure differences between the vasculature of the two groups. In diurnal species, we found an average choroid rete diameter-to-body length ratio (CRD-BLR) of 0.045 and capillary complexity of 13.7 vessels/0.01mm². In nocturnal species, we found an average CRD-BLR of 0.04 and capillary complexity of 18.9 vessels/0.01mm². Though preliminary, these results show no significant difference in CRD-BLR or capillary complexity between diurnal and nocturnal reef fish, suggesting any differences may lie in vascular physiology, rather than choroid rete structure, of these two groups. Further corrosion casting results, together with biochemical analysis of oxygen consumption in the retinal tissue, will be used to determine possible differences in eye vasculature structure and function between diurnal and nocturnal reef fish.