The effect of flow speed and food size on the capture efficiency and feeding behaviour of the cold-water coral Lophelia pertusa

Covadonga Orejas,Andrea Gori,Cecilia Rad-Menéndez,Kim S Last,Andrew J Davies,Christine M Beveridge,Daniel Sadd,Konstadinos Kiriakoulakis,Ursula Witte,John Murray Roberts

doi:10.1016/j.jembe.2016.04.002

Abstract

The capture efficiency and feeding behaviour of the cold-water coral (CWC) Lophelia pertusa (Linnaeus, 1758) were investigated considering: (1) different food types, (2) different food sizes and (3) different current speeds and temperatures. This study used two different multifactorial experimental approaches: (1) Corals were subjected to three different flow speeds (2, 5 and 10cms−1) in 5l volume tanks, and three different food types (alive zooplankton, alive algae, and dry particulate organic carbon) were offered to the corals under each current regime, analysing the capture rates of the corals under these different flow velocities. (2) In a flume, the feeding behaviour of the coral polyps was studied under different current speed regimes (1, 7, 15 and 27cms−1) and a temperature change over a range of 8–12°C. The obtained results confirm that low flow speeds (below 7cms−1) appear optimal for a successful prey capture, and temperature did not have an effect on polyp expansion behaviour for L. pertusa. In conclusion, flow speeds clearly impact food capture efficiency in L. pertusa, with zooplankton predominantly captured prey at low flow velocities (2cms−1) and phytoplankton captured at higher flow velocities of 5cms−1. This split in capture efficiency may allow corals to exploit different food sources under different tidal and flow conditions.

Highlights

Knowledge of the biology and ecology of cold-water corals (CWC) has markedly improved over the last two decades
One of the main focal points of research has been the trophic ecology for some CWC species, principally Lophelia pertusa
Corals were transferred to the aquaria facilities at the Scottish Association for Marine Science (SAMS)

Summary

Introduction

Knowledge of the biology and ecology of cold-water corals (CWC) has markedly improved over the last two decades. One of the main focal points of research has been the trophic ecology for some CWC species, principally Lophelia pertusa. The works by Tsounis et al (2010) and Purser et al (2010) demonstrated that food capture rates and efficiency. Carlier et al (2009) presented the first stable isotope analyses of L. pertusa and demonstrated that zooplankton were the most assimilated prey in the tissue of L. pertusa collected in Mediterranean waters, but signals of phytoplankton were detected. Phytoplankton appears to be one of the main food for other cold-water cnidarians, such as several species of Antarctic gorgonian (Elias-Piera et al, 2013). Determining food sources and assimilation rates are important due to the increasing focus on the ecophysiology of CWC, as certain food sources may play important roles in maintaining basic physiological processes, such as respiration and growth in CWC (Naumann et al, 2011)

Methods

Results

Conclusion