Ocean acidification disrupts the orientation of postlarval Caribbean spiny lobsters

Philip M Gravinese,Samantha Fisher,Clay Hewett,David Lankes,Heather N Page,Angelo Jason Spadaro,Megan Considine,Casey B Butler

doi:10.1038/s41598-020-75021-9

Abstract

Anthropogenic inputs into coastal ecosystems are causing more frequent environmental fluctuations and reducing seawater pH. One such ecosystem is Florida Bay, an important nursery for the Caribbean spiny lobster, Panulirus argus. Although adult crustaceans are often resilient to reduced seawater pH, earlier ontogenetic stages can be physiologically limited in their tolerance to ocean acidification on shorter time scales. We used a Y-maze chamber to test whether reduced-pH seawater altered the orientation of spiny lobster pueruli toward chemical cues produced by Laurencia spp. macroalgae, a known settlement cue for the species. We tested the hypothesis that pueruli conditioned in reduced-pH seawater would be less responsive to Laurencia spp. chemical cues than pueruli in ambient-pH seawater by comparing the proportion of individuals that moved to the cue side of the chamber with the proportion that moved to the side with no cue. We also recorded the amount of time (sec) before a response was observed. Pueruli conditioned in reduced-pH seawater were less responsive and failed to select the Laurencia cue. Our results suggest that episodic acidification of coastal waters might limit the ability of pueruli to locate settlement habitats, increasing postsettlement mortality.

Highlights

In nearshore and shallow coastal waters, seawater pH varies daily and seasonally, often more strongly than in the open ocean because of the smaller water volumes involved[1,2,3]
12.5% of pueruli conditioned in reduced-pH conditions selected the Laurencia spp. cue side of the chamber, which was significantly different from the control
Of the pueruli conditioned in ambient-pH seawater that entered the Y-section of the chamber (n = 14), 100% oriented toward the Laurencia spp. cue side

Summary

Introduction

In nearshore and shallow coastal waters, seawater pH varies daily and seasonally, often more strongly than in the open ocean because of the smaller water volumes involved[1,2,3]. The variation in coastal seawater pH is driven by a number of processes that can occur simultaneously with daily and seasonal fluctuations including benthic biological activity, storms, tidal cycles, and seasonal changes in biogeochemical processes[4,5,6,7,8] Anthropogenic factors such as increased carbon dioxide emissions, increased nutrient-rich runoff, eutrophication, and changes in land use can amplify the acidification of coastal waters in both the short and long t erm[2,9,10]. How reduced seawater pH affects chemosensory behaviour in P. argus postlarvae is not known but is of critical importance, given the sensitivity of P. argus to chemosensory stimuli and the behavioural impairment reported for juvenile P. argus under acidified c onditions[27]

Methods

Results

Conclusion