The Effects of Temperature, Light, and Feeding on the Physiology of Pocillopora damicornis, Stylophora pistillata, and Turbinaria reniformis Corals

Abstract

Evidence has shown that individually feeding or reduced light can mitigate the negative effects of elevated temperature on coral physiology. We aimed to evaluate if simultaneous low light and feeding would mitigate, minimize, or exacerbate negative effects of elevated temperature on coral physiology and carbon budgets. Pocillopora damicornis, Stylophora pistillata, and Turbinaria reniformis were grown for 28 days under a fully factorial experiment including two seawater temperatures (ambient temperature of 25 °C, elevated temperature of 30 °C), two light levels (high light of 300 μmol photons m−2 s−1, low light of 150 μmol photons m−2 s−1), and either fed (Artemia nauplii) or unfed. Coral physiology was significantly affected by temperature in all species, but the way in which low light and feeding altered their physiological responses was species-specific. All three species photo-acclimated to low light by increasing chlorophyll a. Pocillopora damicornis required feeding to meet metabolic demand irrespective of temperature but was unable to maintain calcification under low light when fed. In T. reniformis, low light mitigated the negative effect of elevated temperature on total lipids, while feeding mitigated the negative effects of elevated temperature on metabolic demand. In S. pistillata, low light compounded the negative effects of elevated temperature on metabolic demand, while feeding minimized this negative effect but was not sufficient to provide 100% metabolic demand. Overall, low light and feeding did not act synergistically, nor additively, to mitigate the negative effects of elevated temperature on P. damicornis, S. pistillata, or T. reniformis. However, feeding alone was critical to the maintenance of metabolic demand at elevated temperature, suggesting that sufficient supply of heterotrophic food sources is likely essential for corals during thermal stress (bleaching) events.

Low-level nutrient enrichment during thermal stress delays bleaching and ameliorates calcification in three Hawaiian reef coral species

“…5 , Table S9 ), the species with the highest heterotrophic feeding rate during post-bleaching recovery. This concurs with other studies that report M. capitata was able to obtain up to 100% of the required metabolic energy requirements from heterotrophy ( Dobson et al, 2021 ; Grottoli, Rodrigues & Palardy, 2006 ). Alternatively, the relatively poor response of P. acuta to heating in this study may have been driven by its limited ability to regulate endosymbiont proliferation ( Fox et al, 2021 ).…”

Peer Review #3 of "Low-level nutrient enrichment during thermal stress delays bleaching and ameliorates calcification in three Hawaiian reef coral species (v0.1)"

“…5, Table S9), the species with the highest heterotrophic feeding rate during post-bleaching recovery. This concurs with other studies that report M. capitata was able to obtain up to 100% of the required metabolic energy requirements from heterotrophy (Dobson et al 2021;Grottoli et al 2006). Alternatively, the relatively poor response of P. acuta to heating in this study may have been driven by its limited ability to regulate endosymbiont proliferation (Fox et al 2021).…”

Coastal ecological impacts from pumice rafts

“…Reef-building corals maintain photosynthetic algae (zooxanthellae) that live in their tissues and play a critical role in supplying the coral with glucose, glycerol, and amino acids, which are the products of photosynthesis under energetic consequences of flexible symbiont associations (i.e., mutualistic relationships) 49 . If the symbiotic relationship breaks down, the coral tissue will turn white (bleaching), and in the worst case, the coral will die 50 , 51 . Besides, pumice rafts may provide the opportunity for any attached species to escape from local unfavorable conditions.…”