Coral reef fish predator maintains olfactory acuity in degraded coral habitats

Abstract

Coral reefs around the world are rapidly degrading due to a range of environmental stressors. Habitat degradation modifies the sensory landscape within which predator-prey interactions occur, with implications for olfactory-mediated behaviours. Predator naïve settlement-stage damselfish rely on conspecific damage-released odours (i.e., alarm odours) to inform risk assessments. Yet, species such as the Ambon damselfish, Pomacentrus amboinensis, become unable to respond appropriately to these cues when living in dead-degraded coral habitats, leading to increased mortality through loss of vigilance. Reef fish predators also rely on odours from damaged prey to locate, assess prey quality and engage in prey-stealing, but it is unknown whether their responses are also modified by the change to dead-degraded coral habitats. Implications for prey clearly depend on how their predatory counterparts are affected, therefore the present study tested whether olfactory-mediated foraging responses in the dusky dottyback, Pseudochromis fuscus, a common predator of P. amboinensis, were similarly affected by coral degradation. A y-maze was used to measure the ability of Ps. fuscus to detect and move towards odours, against different background water sources. Ps. fuscus were exposed to damage-released odours from juvenile P. amboinensis, or a control cue of seawater, against a background of seawater treated with either healthy or dead-degraded hard coral. Predators exhibited an increased time allocation to the chambers of y-mazes injected with damage-released odours, with comparable levels of response in both healthy and dead-degraded coral treated waters. In control treatments, where damage-released odours were replaced with a control seawater cue, fish showed no increased preference for either chamber of the y-maze. Our results suggest that olfactory-mediated foraging behaviours may persist in Ps. fuscus within dead-degraded coral habitats. Ps. fuscus may consequently gain a sensory advantage over P. amboinensis, potentially altering the outcome of predator-prey interactions.

Impacts of Global Warming and Elevated CO2 on Sensory Behavior in Predator-Prey Interactions: A Review and Synthesis

“…As chemical alarm cues are naturally broken down throughout the day (Ferner et al, 2005;Ferrari et al, 2007;Bytheway et al, 2013;Chivers et al, 2013), warming may accelerate these processes in all ecosystems and reduce the effectiveness of chemical alarm cues as reliable indicators of predation risk. In contrast, olfactory preference of dottyback predators toward damaged-released damselfish prey cues is maintained in both healthy and degraded coral environments (Natt et al, 2017). This suggests that some predators may have a sensory advantage over prey in degraded coral habitats, potentially altering the outcome of predator-prey interactions.…”

Micro‐CT reconstruction reveals the colony pattern regulations of four dominant reef‐building corals

“…Their diverse and varied growth forms provide a habitat and food for the many thousands of reef‐associated organisms (Ellison et al, 2005 ; Graham, 2014 ; Knowlton et al, 2010 ; Weis et al, 2008 ), making tropical reefs centers of biodiversity. Tropical coral reefs are under pressure from a range of local and global environmental stressors (Carpenter et al, 2008 ; Kleypas et al, 1999 ; Maynard et al, 2015 ), including global warming (Bellwood et al, 2004 ; De'ath et al, 2012 ; Jokiel & Coles, 1977 ) and ocean acidification (Mollica et al, 2018 ; Tambutté et al, 2015 ); environmental pollution (Kroon et al, 2019 ; Mantelatto et al, 2020 ) – for example, microplastics (Jeyasanta et al, 2020 ; McCormick et al, 2020 ; Patterson et al, 2020 ; Patti et al, 2020 ) and heavy‐metal contamination (Banc‐Prandi et al, 2020 ; Jafarabadi et al, 2020 ; Nour & Nouh, 2020 ; Yang et al, 2020 ); and overexploitation (Heard et al, 2020 ; Natt et al, 2017 ; Robinson et al, 2016 ), making the protection and ecological restoration of coral reefs critical. Studies on these predominant reef‐building corals are, therefore, gaining widespread traction (Adjeroud et al, 2009 ; Bramanti & Edmunds, 2016 ; Cunning et al, 2018 ; Edmunds et al, 2014 ; Kayal et al, 2012 , 2015 ; Liang et al, 2017 ; Stolarski et al, 2016 ).…”

The 3D Reconstruction of Pocillopora Colony Sheds Light on the Growth Pattern of This Reef-Building Coral

“…Reef-building scleractinian corals provide complex three-dimensional niches for various species (Costanza et al, 2014;Ellison et al, 2005;Knowlton et al, 2010;Weis et al, 2008;Graham, 2014). However, coral reefs are currently declining globally because of the climate change (Carpenter et al, 2008;Kleypas et al, 1999;Maynard et al, 2015), especially owing to the intensification of El Niñ o (Jokiel and Coles, 1977;Bellwood et al, 2004;De'ath et al, 2012), water-quality deterioration (Tambutté et al, 2015;Mollica, 2018), and overexploitation (Natt et al, 2017;Robinson et al, 2017). Studies on the biochemical processes governing coral reef and their ecological health under environmental changes are therefore undoubtedly in the spotlight (Fabricius et al, 2010).…”