Differential effects of thermal and chemical stressors on tissue balls from scleractinian corals

Abstract

Coral cell aggregates (tissue balls) from four species (Acropora muricata, Fungia repanda, Pavona cactus andPocillopora damicornis) were used as an indicator to investigate the effects on the corals of thermal stress and of chemical extracts from three sponges (Adocia sp., Haliclona sp. and Lissodendoryx sp.) and one ascidian (Didemnum molle). The formation and disintegration of tissue balls were studied through exposure to a temperature range of 23-30 °C at time intervals of 0-90 min, and to sponge and ascidian crude extracts at concentrations of 50-200 μg ml -1 at temperatures of 23 and 30 °C and at time intervals of 10, 60 and 120 min. The negative effect of temperature on overall tissue ball density (number per cm 2 of coral surface) was greatest at higher temperatures (28 and 30 °C) but varied among coral species. Tissue balls of P. damicornis were the most robust whereas those of A. muricata were the most sensitive. High concentrations of extracts of Adocia sp., Haliclona sp. and Lissodendoryx sp. generally inhibited the formation of tissue balls or caused their disintegration, or both, most markedly at 30 °C. Adocia sp. induced the least negative effects and Haliclona sp. the most. No tissue balls were formed in the presence of D. molle extracts (50 and 100 μg ml -1 ), indicating a high level of interference with tissue ball formation. The differential susceptibility to thermal and chemical stressors exhibited by the corals under study have possible implications for the interactions of the corals with other sedentary reef organisms under climate change-driven ocean warming.

Photo-physiological responses and thermal tolerance of regionally endemic/rare and morphologically different corals of the Western Indian Ocean

“…Furthermore, it was found that tabular A. branchi, A. hyacinthus and branching P. cylindrica were the most susceptible to bleach and die after 6 hours of exposure to a persistent warmer environment. On the other hand, P. lutea, G. fascicularis, S. hystrix and P. indiania exhibited relatively higher thermal tolerance and these observations concurred with the findings made by van Woesik et al (2011), Mattan-Moorgawa et al (2012, Swain et al (2016) and Cheal et al (2017). Also, previous studies have demonstrated that tabular Acropora displayed signs of highest level of thermal stresses (Eriksson et al 2012;Muko et al 2013) while branching Acropora spp.…”

Differential responses of effective quantum yield to acute thermal stress in scleractinian corals including pre- and post-transplanted Acropora muricata

“…The order of bleaching susceptibility based on their photophysiological response to thermal stress were as follows: A. cytherea > G. fascicularis > P. damicornis > L. repanda. Similar results were highlighted in a study during the bleaching anomaly in 2009 at Belle Mare reporting A. cytherea as most susceptible and P. damicornis, G. fascicularis and L. repanda as more tolerant to thermal stress and mortality (Mattan-Moorgawa et al 2012). It has been suggested that Acropora corals with a higher skeletal surface area to volume ratio are least tolerant to high temperature anomalies compared to those with lower ratio (Fujioka 1999).…”

Differential photo-physiological responses of two giant clam species to elevated temperature stress from Rodrigues Island, Western Indian Ocean

“…It was observed that both species of Tridacna could tolerate the temperature without being much affected in terms of their photophysiological responses. The temperature of 32 o C, that is 3 o C above the normal temperature on a normal summer day (29 o C), was used to mimic the condition of the El Niño or an event of an extreme increase in water temperature as has been recorded previously in the waters of Mauritius (Bhagooli and Taleb-Hossenkhan 2012;Mattan-Moorgawa et al 2012). The results of this study corroborate those of other studies such as Blidberg et al (2000) who investigated the physiological responses of three species of giant clams by exposing them to different elevated temperature stress for 24 hours.…”