Dataset: Gobe nose data

Methodology:

Fish Collection and Rearing (for all histological and SEM analyses) - Mated pairs of E. lori and of E. colini were collected from reef habitats near Carrie Bow Caye, Belize and housed in 75-l aquaria in a flow-through seawater lab at the International Zoological Expeditions (IZE) field station on South Water Caye, Belize, or in a recirculating seawater system at Boston University, USA. Ontogenetic series of E. lori and E. colini larvae were reared in 76-l cylindrical black bins and fed a variety of cultured and wild-caught zooplankton (Figure 1). A detailed description of brood stock maintenance and larval rearing methods can be found in Majoris et al. (2018). Additional post-settlement E. lori and E. colini (settlers) were collected from reef habitats within the South Water Caye Marine Reserve. Field research in Belize and the export of samples from Belize was carried out with the approval of the Belize Fisheries Department. Fish were immersed in cold seawater (2-4 degrees C) for two minutes and then fixed in cold (2-4 degrees C) 10% formalin in seawater (or in phosphate-buffered saline, PBS) for at least two minutes for anatomical study, which is consistent with AVMA Guidelines on Euthanasia of small warm-water fish. Care was taken to ensure that fish did not contact ice directly. Chemical anaesthetic was not used for several reasons, in particular because fixation must occur prior to death to avoid post-mortem changes at the cellular level, and ensure quality of the histological data and specimens prepared for SEM.

Olfactory Organ Analysis - The length of the olfactory epithelium (rostro-caudal axis) was calculated as the number of transverse sections containing sensory tissue multiplied by section thickness (5 m). In each individual, images were captured at positions 25%, 50% and 75% along the rostro-caudal length of the left olfactory epithelium (or the right epithelium, if the left one was damaged), with a Zeiss AxioCam camera mounted on a Zeiss AxioImager1 compound microscope and analyzed using ImageJ. Sensory epithelium width was determined in images of each of the three sections by measuring the epithelium halfway between the apical cell surface and basement membrane; epithelium thickness (from apical surface to basement membrane) was also measured in the middle of the epithelium in the same three sections. The mean of three measurements for each parameter was used in subsequent analyses.