Biofluorescence as a survey tool for cryptic marine species

Abstract

As ecosystems come under increasing anthropogenic pressure, rare species face the highest risk of extinction. Paradoxically, data necessary to evaluate the conservation status of rare species are often lacking because of the challenges of detecting species with low abundance. One group of fishes subject to this undersampling bias are those with cryptic body patterns. Twenty-one percent of cryptic fish species assessed for their extinction risk (International Union for Conservation of Nature [IUCN]) are data deficient. We developed a nondestructive method for surveying cryptically patterned marine fishes based on the presence of biofluorescence (underwater biofluorescence census, UBC). Blue LED torches were used to investigate how widespread biofluorescence was in cryptic reef fishes in the Coral Triangle region. The effectiveness of UBC to generate abundance data was tested on a data-deficient pygmy seahorse species (Hippocampus bargibanti) and compared with data obtained from standard underwater visual census (UVC) surveys. We recorded 95 reef fish species displaying biofluorescence, 73 of which had not been previously described as biofluorescent. Of those fish with cryptic patterns, 87% were biofluorescent compared with 9% for noncryptic fishes. The probability of species displaying biofluorescence was 70.9 times greater for cryptic species than for noncryptic species. Almost twice the number of H. bargibanti was counted using the UBC compared with UVC. For 2 triplefin species (Ucla xenogrammus, Enneapterygius tutuilae), the abundance detected with UBC was triple that detected with UVC. The UBC method was effective at finding cryptic species that would otherwise be difficult to detect and thus will reduce interobserver variability inherent to UVC surveys. Biofluorescence is ubiquitous in cryptic fishes, making this method applicable across a wide range of species. Data collected using UBC could be used with multiple IUCN criteria to assess the extinction risk of cryptic species. Adopting this technique will enhance researchers' ability to survey cryptic species and facilitate management and conservation of cryptic marine species.

The hidden half: ecology and evolution of cryptobenthic fishes on coral reefs

“…Increasing underwater technology that will facilitate detection (e.g. via fluorescence) and photographic capture of CRFs is likely to further increase their contribution to the diving industry (De Brauwer et al , ).…”

Light and Autofluorescence, Multitasking Features in Living Organisms

“…Fluorescence may occur in fishes belonging to different species, in part still unidentified because of a cryptic living behavior. In fishes populating coral reef areas biofluorescence has been recommended as a valuable tool in the search and surveillance of otherwise poorly detectable rare species [203]. It has been also reported that many of the fluorescing fishes, including sharks and rays, possess a good vision and the presence of intraocular yellow filters, likely facilitating their ability to detect this fluorescence at wavelengths longer than the blue or dark in aquatic environment.…”

Shining in the dark: First record of biofluorescence in the seahorse Hippocampus reidi

“…bargibant and H . denise ) and also pipefish species of the Syngnathidae family, in relation to the occurrence of green and red biofluorescence [13,14,7,3].…”

“…bargibant and H . denise [13], especially in relation to the eyes. Green fluorescence has been reported to attract preys in hydromedusa and has an effective result during day light [20].…”

“…Worldwide, biofluorescence was recently reported for the Syngnathidae family, and only to four seahorse species, H . erectus , Hippocampus zosterae Jordan and Gilbert, 1882 [3], Hippocampus bargibanti Whitley, 1970 and Hippocampus denise Lourie and Randall, 2003 [13]. The present study aimed to check for biofluorescence in the seahorse H .…”