Reef Odor: A Wake Up Call for Navigation in Reef Fish Larvae

Abstract

The behavior of reef fish larvae, equipped with a complex toolbox of sensory apparatus, has become a central issue in understanding their transport in the ocean. In this study pelagic reef fish larvae were monitored using an unmanned open-ocean tracking device, the drifting in-situ chamber (DISC), deployed sequentially in oceanic waters and in reef-born odor plumes propagating offshore with the ebb flow. A total of 83 larvae of two taxonomic groups of the families Pomacentridae and Apogonidae were observed in the two water masses around One Tree Island, southern Great Barrier Reef. The study provides the first in-situ evidence that pelagic reef fish larvae discriminate reef odor and respond by changing their swimming speed and direction. It concludes that reef fish larvae smell the presence of coral reefs from several kilometers offshore and this odor is a primary component of their navigational system and activates other directional sensory cues. The two families expressed differences in their response that could be adapted to maintain a position close to the reef. In particular, damselfish larvae embedded in the odor plume detected the location of the reef crest and swam westward and parallel to shore on both sides of the island. This study underlines the critical importance of in situ Lagrangian observations to provide unique information on larval fish behavioral decisions. From an ecological perspective the central role of olfactory signals in marine population connectivity raises concerns about the effects of pollution and acidification of oceans, which can alter chemical cues and olfactory responses.

Wind Conditions on the Great Barrier Reef Influenced the Recruitment of Snapper (Lutjanus carponotatus)

“…This represents the chemotaxis driven orientation documented in the larvae of many coral reef fish species, where they can swim to reefs by discriminating between water with a reef odor and oceanic water (e.g., Paris et al, 2013). Wolanski and Kingsford (2014) simulated the odor plume from OTI and found it extended several kilometers from the reef.…”

“…In addition to physical oceanographic features, the biological characteristics of fish larvae can greatly affect their dispersion (Kingsford et al, 2002;Paris et al, 2013;Wolanski and Kingsford, 2014;Bottesch et al, 2016). The larvae of many fish species can maintain swim speeds that exceed local mean current speeds for extended periods of time, they can, therefore, influence their dispersal trajectories (Fisher, 2005;Leis, 2006).…”

“…The larvae of many fish species can maintain swim speeds that exceed local mean current speeds for extended periods of time, they can, therefore, influence their dispersal trajectories (Fisher, 2005;Leis, 2006). They can also orient to reefs using a variety of senses including a sun compass (e.g., Leis and Carson-Ewart, 2003;Mouritsen et al, 2013) and a magnetic compass (e.g., Bottesch et al, 2016) for long distance orientation, and hearing (e.g., Mann et al, 2007;Wright et al, 2010) and chemotaxis (e.g., Gerlach et al, 2007;Dixson et al, 2008;Paris et al, 2013) when they are closer to reefs. The exceptional swimming and orientation abilities of reef fish larvae, in combination with hydrodynamic retention mechanisms near reefs, may prevent the expatriation of some larvae away from natal reefs (Almany et al, 2007;Andutta et al, 2012).…”

Response of Gilthead Seabream (Sparus aurata L., 1758) Larvae to Nursery Odor Cues as Described by a New Set of Behavioral Indexes

“…Potential larval stimuli include water pressure gradients (Burke et al, 1995), magnetism (Qin et al, 2015), visual (Whitfield, 1994;Faillettaz et al, 2015), auditory (Staaterman et al, 2014), and odor-based cues (McCormick and Manassa, 2008;Arvedlund and Kavanagh, 2009), which may be used in tandem to identify suitable habitats (Lecchini et al, 2005;Hale et al, 2008). These environmental cues will then trigger a variety of larval behaviors, such as orientation (Paris et al, 2013;Faillettaz et al, 2015), vertical migration (Fortier and Leggett, 1983), predator avoidance (Lehtiniemi, 2005), and habitat selection (Gerlach et al, 2007).…”

“…Fish larvae perceive odor cues over greater distances than any other cue (Teodósio et al, 2016), and they can distinguish the chemical signatures present in the water to pinpoint the location of a nursery habitat (Atema et al, 2002;Døving et al, 2006;Paris et al, 2013). Chemical signatures are determined by abiotic or biotic factors, as type of substrate (V. Baptista, CCMAR, unpublished data), vegetation (Radford et al, 2012), or chemical signals released by conspecifics (Døving et al, 2006).…”