Enduring physiological and reproductive benefits of enhanced flow for a stony coral

Abstract

We experimentally examined the in situ, long-term effects of flow on the coral Pocillopora verrucosa over a 2-yr period. Eighteen coral nubbins were positioned on stages protected from the ambient flow with transparent walls. Six of the corals were exposed to ''enhanced flow'' with underwater pumps (15-20 cm s 21 ), while another other six were grown under ''reduced-flow'' conditions (, 1 cm s 21 ), and a further six nubbins were set up as a control treatment exposed to ambient natural flow conditions on stages without walls. Mortality was 50% in the reducedflow experiment. Compared with the reduced-flow and the control treatments, colonies growing in enhanced-flow conditions developed a more compact morphology and had significantly higher chlorophyll and protein concentrations, a higher density of zooxanthellae, and, most importantly, higher reproductive output. However, corals grown in reduced-flow conditions had lower skeleton density compared with those grown under ambient flow or enhanced flow. Flow rate had no measurable influence on average pH at the site of calcification as monitored by skeletal boron isotopic composition (d 11 B). Hence, the skeletal d 11 B-pH proxy in this coral appears to be independent of flow and the biological attributes that are modulated by flow, such as zooxanthellae density, chlorophyll concentrations, and rates of photosynthesis, respiration, and calcification. Calcification site pH in all colonies was raised by +0.3 relative to ambient seawater pH. Together with light, flow should be considered a key abiotic factor determining core biological characteristics of P. verrucosa.

Switch between Morphospecies of Pocillopora Corals

“…2, A1) may explain why P. inflata has been observed in some surveys, only to be absent after 1-3 years in subsequent surveys (Glynn 1999). In addition, a few studies that have monitored the morphology of Pocillopora corals for 9-24 months have reported similar changes in swollen branches (Nakamura and Yamasaki 2006;Mass et al 2011;see below). Our findings show that some coral colonies can maintain their morphology over long periods (unchanged colonies over more than 3 years, fig.…”

“…For example, transplanted fragments of P. damicornis began to develop thicker, more swollen branches after 9 months of constant high (20 cm/s) flow (Nakamura and Yamasaki 2006). Pocillopora verrucosa also developed short but swollen branches after 2 years in higher flow (Mass et al 2011). Models also predict that thicker, swollen branches will be induced by high water flow and light availability (Filatov et al 2010;Chindapol et al 2013).…”

Testing the limitations of artificial protein degradation kinetics using known-age massive Porites coral skeletons

“…Calcification occurs extracellular but under strictly controlled conditions (e.g. Mass et al, 2011) beneath the calicoblastic tissue, isolated from seawater by two layers of tissue and the coelenteron. Since the skeleton cores come from living colonies it would be incorrect to refer to the samples as 'fossils'; instead we refer to them as 'naturally aged' to distinguish them from the experimentally heated samples.…”

Modelling Growth and Form of the Scleractinian Coral Pocillopora verrucosa and the Influence of Hydrodynamics

“…(B) A coral that was grown in an in situ controlled flume setup with “reduced flow” condition (∼1 cm s −1 ) (C–E) Corals were grown in the in-situ controlled flumes setup with “enhanced flow” condition (15–20 cm s −1 ) [32]. Arrows indicate flow direction.…”