Seasonal Variation in Subtidal Seaweed Community Structure at Hajung, on the Southeast Coast of Korea

Abstract

Subtidal benthic macroalgal flora and community structure on barren grounds were examined seasonally along vertical shore gradients on the rocky shore of Hajung, Pohang, on the southeast coast of Korea, from February 2005 to November 2006. Twenty-six seaweed species were identified, including 5 green, 7 brown, and 14 red algae. The number of seaweed species ranged between 7 and 17 among seasons and between 13 and 20 species were found in vertical gradients along the shore. Over the study period, average seaweed biomass (g wet wt/m 2 ) was 299.88 g and it ranged seasonally from 120.99 to 620.00 g. Seaweed biomass declined with increasing seawater depth and ranged between 323.06 and 593.68 g. The dominant seaweed species, in terms of biomass, were Desmarestia ligulata and Sargassum honeri, which grew at depths between 5 and 10 m. The red alga Delisea pulchra was also abundant at a depth of 15 m. No seasonal patterns were found in community indices. Along vertical shore gradients, community indices showed different patterns; the dominance index increased and the richness, evenness, and diversity indices decreased with seawater depth.

In-Situ Estimates of Net Ecosystem Metabolisms in the Rocky Habitats of Dokdo Islets in the East Sea of Korea

“…In Japan, the periodic intrusion of the warm Tsushima Current along the coast produces mass mortality of Ecklonia and Eisenia species in rocky habitats, which are replaced by tropical species (Sargassum ilicifolium) on the small spatial scale for a short time [6]. Similar to the situation in Japan, kelp beds are rapidly disappearing from the coastlines of the Korean peninsula and are replaced by the whitening of CCA [7,59,60]. Considering that the increase in the annual mean surface water temperature around Korea is about three-times higher than that of the global trend over the last five decades, the physiological interaction in the benthic community by thermal effect may be closely related to the contraction of kelp and expansion of CCA [61].…”

Effects of Irradiance and Temperature on the Photosynthesis of the Crustose Coralline Algae Pneophyllum fragile (Corallinales, Rhodophyta) in the Coastal Waters of Korea

“…In fact, isoyake (the word for whitening in Japan) has reduced commercial seaweed (Gelidium, Saccharina, Eckonia, and Sargassum) levels over the past couple of decades, and resulted in a decrease in fisheries production [42]. Recently, whitening has spread throughout Korean coastal waters (from Jeju Island to Dokdo Island), and kelp forest restoration projects have been initiated to recover the benthic ecosystem [2,3,43]. However, the results of these efforts remain unclear because the physiological characteristics of CCA and the precise mechanisms associated with whitening outbreaks are unknown.…”

“…Whitening can reduce the biomass and biodiversity of the benthic habitat, which are major factors associated with the devastation of the benthic ecosystem [1]. Since the 1990s, a massive outbreak of whitening has been observed in the coastal waters of Korea and it has gradually expanded into the subtidal habitats [1][2][3][4]. In particular, the whitening detected in the coastal waters of Jeju Island has rapidly expanded from 2913 ha in 1998 to 4541 ha in 2004, and is considered a threat to the coastal ecosystem.…”

“…Recently, studies of whitening in the coastal waters of Korea have been initiated to restore the macroalgae meadows and assess their ecological functions [1][2][3][4]. However, most of the studies focused on the monitoring of the occurrence and evolution area of whitening because of the absence of appropriate methods to estimate CCA metabolism [24,25].…”

Effects of Temperature on the Spore Release and Growth of Lithophyllum yessoense and Hildenbrandia rubra

“…(lateral growth) , , (Dethier, 1994), (Fujita et al, 1992;Gherardi and Bosense, 2001), (Littler et al, 1985;Steneck, 1986). , (Isoyake) (Chung et al, 1998;Wilson et al, 2004), (Noro et al, 1983;Chung et al, 1998;Ichiki et al, 2000;Kim et al, 2011).…”