Stress Resistance and Adaptation of the Aquatic Invasive Species Tubastraea Coccinea (Lesson, 1829) to Climate Change and Ocean Acidification

Kevin B Strychar,Joshua A Haslun,Jessica Deboer,Katherine Cryer,Briana Hauff-Salas,Scott Keith,Sam Wooten

doi:10.3390/w13243645

Abstract

A great number of studies published on long-term ocean warming and increased acidification have forecasted changes in regional biodiversity preempted by aquatic invasive species (AIS). The present paper is focused on invasive Tubastraea coccinea (TC), an azooxanthellate AIS coral thriving in regions of the Gulf of Mexico, which has shown an ability to invade altered habitats, including endemic Indo-Pacific T. coccinea (TCP) populations. To determine if invasive TC are more stress resistant than endemic Indo-Pacific T. coccinea (TCP), authors measured tissue loss and heat shock protein 70 (HSP70) expression, using a full factorial design, post exposure to changes in pH (7.5 and 8.1) and heat stress (31 °C and 34 °C). Overall, the mean time required for TCP to reach 50% tissue loss (LD50) was less than observed for TC by a factor of 0.45 (p < 0.0003). Increasing temperature was found to be a significant main effect (p = 0.004), decreasing the LD50 by a factor of 0.58. Increasing acidity to pH 7.5 from 8.1 did not change the sensitivity of TC to temperature; however, TCP displayed increased sensitivity at 31 °C. Increases in the relative density of HSP70 (TC) were seen at all treatment levels. Hence, TC appears more robust compared to TCP and may emerge as a new dominant coral displacing endemic populations as a consequence of climate change.

Highlights

Under current global climate change projections where both marine and freshwater habitats are expected to continue to change, i.e., become warmer and more acidic [1], invasive species are anticipated to continue to increase in drastic numbers, altering environments on a large scale
Invasive species have high potential to alter the ecosystems in which they reside, their impacts may exponentially increase if they are simultaneously able to resist the changing climate coupled to reduced predation and are less susceptible to disease
Tubastraea coccinea (TC) has become a successful invader in the Western Atlantic probably due to its ability to withstand the effects of our changing climate as compared to its congener in the Indo-Pacific (TCP)

Summary

Introduction

Under current global climate change projections where both marine and freshwater habitats are expected to continue to change, i.e., become warmer and more acidic [1], invasive species are anticipated to continue to increase in drastic numbers, altering environments on a large scale. Complications in the marine environment stemming from increased atmospheric CO2, including increases in sea surface temperatures and ocean acidification, will change conditions such that endemic organisms will need to adapt or perish under competition from more fit and/or less predated individuals [3,4]. We discuss the ahermatypic, azooxanthellae (lacking an algal symbiont) coral Tubastraea coccinea as an invasive species in the Caribbean and Gulf of Mexico [9,10,11,12,13] and discuss its potential resilience to climate change. Orange cup coral, and/or golden flower coral, this species experiences little to no predation in the Caribbean and Gulf of Mexico [24,25] albeit Epidendrium billeeanum (gastropod snail) has been reported to feed on this species in the eastern Pacific [26,27]. As no fossils of T. coccinea have been found in the Caribbean [42], it is clear that T. coccinea is an invasive colonizer that negatively affects indigenous benthic organisms in the Western Atlantic

Methods

Results

Conclusion