Effects of wave action and grazers on frond perforation of the green alga, Ulva australis

doi:2015.30.1.59

Algae > Volume 30(1); 2015 > Article

Algae 2015;30(1): 59-66. doi: https://doi.org/10.4490/algae.2015.30.1.059

Han Gil Choi¹^,*, Bo Yeon Kim¹, Seo Kyoung Park¹, Jin Suk Heo¹, Changsong Kim², Young Sik Kim² and Ki Wan Nam³

¹Faculty of Biological Science and Institute of Basic Natural Sciences, Wonkwang University, Iksan, 570-749, Korea
²Department of Marine Biotechnology, Kunsan National University, Kunsan, 573-701, Korea
³Department of Marine Biology, Pukyong National University, Busan 608-737, Korea

*Corresponding Author

Email: hgchoi@wku.ac.kr

ABSTRACT

The growth and hole formation of Ulva australis were examined at seven coastal areas of Korea between July and August, 2013. Animal species and weight growing on the Ulva fronds were estimated at Haseom, Pohang, and Woedo. The effects of wave exposure on the morphological features and residential animals of Ulva fronds were investigated at wave-exposed and sheltered sites of Seongsan on October 19, 2013. U. australis had different frond areas (82-665 cm2), hole areas (2.5-6.3 cm2), and hole numbers (9.8-41.3 holes) at the seven sites. Within 0.1 m2 of Ulva frond, hole areas ranged from 0.37 to 5.94 cm2, and between 4.9 and 36.2 holes were observed. Fourteen residential animal species were observed at the three evaluated sites, 75.0 (Haseom) to 408.7 individuals 100 g-1 Ulva (Pohang) per site. The dominant residential species at each site differed with Amphithoe sp. at Haseom, Monodonta spp. at Pohang, and Pagurus sp. at Woedo. The growth (frond area, wet weight) and hole number of Ulva fronds, and the number of residential animals were significantly greater in samples collected from the sheltered shore than the wave-exposed shore of Seongsan. The present results showed U. australis grew well at sheltered shores and had more holes on the fronds due to abundance of residential animals. The dominant residential animals (crabs, gammaridea, and snails) were similar in the Ulva populations of sheltered and wave-exposed shores, but greater species diversity was observed at the exposed shore (18 species ver. 11 species). In conclusion, U. australis is a keystone species providing habitat to various invertebrates and frond holes are positively correlated to the number of residential animals.

Key words: grazer; growth; hole formation; Ulva australis; wave action