Destruction of seaweed habitats along the coast of the Korean peninsula and its consequences

Large seaweeds can form dense underwater forests. These forests provide a physical structure that supports marine communities by providing animals with food and shelter. Until the end of 1980, Sargassum, Laminaria and Ecklonia forests were abundant all along Korean peninsula except the western coast of the peninsula (i.e., Yellow Sea) where the sea bottom is composed of mud. From the beginning of 1990s, however, these forests had been decreasing due to various reasons such as global warming, sea urchin grazing, industrialization near the shores, and over releasing of abalone without consideration of carrying capacity of rocky habitats, and by the end of 2004, ca. 13% of the eastern coast of the peninsula (i.e., East Sea) and 31.4% of the coastal zone of Jeju island in South Sea became barren ground with crusty pink algae and little else covering the rocks (Fig. 1, Table 1). Construction of artificial seaweed beds, therefore, is presently looked into as a necessary factor for the recovery of natural resources. Of the seaweed species, Sargassum, Laminaria and Ecklonia are of interest in Korea. Various techniques have been applied to construct artificial seaweed beds (Fig. 2). Here, I introduce some of the techniques as below:1

Seaweed Community of the Subtidal Rocky Habitats along the Coast of Geumo Archipelago in the Central South Sea of Korea

Seaweed community of the subtidal rocky habitats along the coast of Geumo Archipelago in the central South Sea of Korea is described. This area is characterized by archipelago in which islets are separated by shallow bottom sediments (primary, muddy sand), and turbidity is generally high due to the resuspension of bottom sediments. The hard substrata available for algal attachment are limited to less than 10 m in depth. Thirty sites were randomly chosen along the coast from August 2003 to September 2003 and a 50 m long transect was established at each site. The transect began at a depth of 1 m and ended at the depth of 9 m. The percent cover of all species other than crustose coralline algae was estimated at 2 m depth intervals along the transect using a 0.25 m2 PVC quadrat with 25 squares. Thirty-six species were identified including 6 Chlorophyta, 10 Phaeophyta and 20 Rhodophyta. Species with more than 5% mean bottom cover were Gelidium amansii, Corallina pilulifera, Amphiroa dilatata and Carpopeltis cornea, which formed dense turf-forming algal assemblages at 1-5 m depth. At all sites except S11-S15 located in the western coast of Sorido, bottom covers of seaweed species at the depth deeper than 7 m were less than 6%. The lower limit of algal assemblages was 9 m in depth. We speculate that the limited water clarity and vertical extent of hard substrata available for the settlement of seaweed species are the direct cause of reducing the diversity, abundance and distributional extent of algal assemblages in the area.22Nkc

Habitat improvement for marine ranching in Korea

Aquatic habitat improvement is a key element of the marine ranching program conducted in Korea. There are three types of habitat improvement: Restoration-returning a habitat to its original condition, Rehabilitation-returning a habitat to some other state, and Enhancement-the process of adding something different to a habitat. Several activities for aquatic habitat improvement in our marine ranching program are consistent with Enhancement. Our missions are to monitor the physicochemical environment, document the topography of ranching areas, estimate the production of all marine biota, measure the carrying capacity using an ecosystem model based on the ecological interactions between the biota, and to improve fish habitats by deploying various types of artificial reefs and constructing marine forests.1

Distribution Patterns of the Dominant Macrobenthos and Their Relations to the Benthic Environments on Subtidal Soft-bottom in Chonsu Bay, Korea

Dominant species on a macrobenthic communities make selection by several methodology. This study executed to analyze differentiation of three types methods, density based, biomass based and Le Bris method considering to frequency occurrence using the quantitative data during five year, 1993 to 1998, at 21 stations in Chonsu Bay. Sedimentary environments as well as species composition and diversity showed the spatial and temporal distribution patterns. The rank of dominant species by density based listed similar to the results by Le Bris method than biomass based. Considering to the temporal variation, Le Bris method were more efficient than any other methods when made a selection of dominant species in Chonsu Bay. Three of species, Lumbrineris longifolia, Theora fragilis, Moerella jedoensis were included in all of methods. As results for one-way ANOVA, most of dominant species characterized to the spatial distribution patterns. These species showed positive correlations to sedimentary environments such as mean grain size. But only two species, T. fragilis, P. pinnata affected to the temporal patterns on their distribution, and also showed the correlations to benthic environments, organic contents and dissolved oxygen. Some of dominant species, T. fragilis, S. scutata, G. gurjanovae showed the possibilities of benthic indicator according to the environmental variations which can applying to the long-term benthic ecological monitoring in Chonsu Bay.22Nkciothe

Morphological and genetic variability among Ecklonia cava Kjellman (Laminariales, Phaeophyta) populations in Korea

Ecklonia cava Kjellman is a common macroalga on rocky reefs in the warm-temperate part of Korea. It often forms dense subsurface canopies, playing an important role as nursery and breeding space for commercial fishes. E. cava surveys were first conducted along a 180 km length of southern Korea between 2003 and 2004, indicated that the external morphology of adult E. cava sporophytes were highly variable along environmental gradients and contributed to confusion about its taxonomy. We quantified the magnitude of morphological and genetic variation in fully developed E. cava across its geographic range in Korea using conservative morphological comparisons and RAPD analysis during the period from March 2007 to May 2007. A total of nine morphological characters were sampled from 6 locations along ~700 km coastline from Jeju Island to Dokdo. All morphological characters investigated were significantly different among locations. There were consistent patterns of spatial variation in individual morphological characters: in most morphological characters, populations (e.g., Yeosu) in turbid nearshore areas and sheltered or semi-exposed showed considerably lower values, compared to those (e.g., Jeju Island) in clear nearshore or offshore areas and semi-exposed or exposed. In addition, most characters were moderately to highly correlated to each other (0.5< R <1.0), suggesting that most morphological characters develop dependently of each other. Multivariate analyses indicated that there were two phenetically distinct groups, and stipe length was the character largely contributing to separating the two groups. For RAPD analysis, a total of 155 discernible and reproducible RAPD bands were generated with 9 selected primers across the 116 individuals of six locations, out of which 56 (36.1%) were polymorphic. The Nei’s diversity (H) varied among locations, ranging from 0.192 to 0.225, with an average value of 0.205. AMOVA showed that the variance components of within and between1

Spatial distribution of corals and fisheries relation to the reefs formation based on topography around Kosrae Island,FSM

This study have carried to get the approximate state of the coral reefs and to provide a basic information concerning to quantitative stocks of fisheries such as Trochus, Giant clam, around Kosrae island. The topographical characteristics were divided to three types, reef flat, slope and small ravine, approximately. First type have composed to the slope flat type and complicated topography by the clump of brain corals, Acropora sp., Diploastrea sp., Montastera sp. And so on., until 15m depth, and spreaded to deep slope along the deep area . Second type have composed deep slopes than the first type area and formed the small ravine partially Coralline debris and breakages have accumulated on the ravine. Strong downward currents flowed from shallow area to deep area along to the ravine. The corals,, Montastera sp., showed terrace shape along the slope. Third type also showed similar to second type in topographical shape. Branching type coral, Porites sp., and fan coral, Montipora aequituberulata, scattered between 8m to 15m depth.1

The fish fauna in Chuuk, Micronesia

More than 264 species were observed at 12 research stations of Chuuk and Quop atoll. Total 317 species were recorded in Cuukish waters involved Moen atoll, Nomwin atoll and Kuop atoll. In this data, unvisual small fishes living in sand bottom and coral polyps were excepted. 222 fish species were observed in Chuuk atoll, 108 species in Namwin and 181 species in Kuop atoll (Table 2). In some station of Chuuk lagoon, we found destroyed marine ecosystem by using explosive for fisheries. Those stations showed low fish species diversity.1

Population Studies on the Kelp Ecklonia cava and Eisenia bicyclis in Dokdo, Korea

The vertical distribution, density and biomass, population composition, and morphometric parameters of the kelp Ecklonia cava and Eisenia bicyclis were investigated in the subtidal zone of Dokdo during the summer of 2000. In most area, Ecklonia cava occurred in the depth range from 2 m to 10 m, and showed the highest density and biomass at 5 m. Ecklonia cava also occurred from 2 m, but its vertical limit was extended to deeper than 25 m. In addition, E. cava formed the conspicuous belt in depth range from 10 to 25 m, with the highest density and biomass between 15 and 20 m. The density and biomass of E. cava in its vertical distribution range were 3.0 to 372.2 inds m super(-2) and 1.2 to 21.6 kg wwt m super(-2), whereas those of Eisenia bicyclis were 6.6 to 117.5 inds m super(-2) and 7.6 to 29.0 kg wwt m super(-2). The average length and wet weight of E. cava were 26.0 ± 32.7 cm and 64.0 ± 160.8 g, and those of E. bicyclis were 34.2 ± 41.4 cm and 226.8 ± 465.7 g. Total biomass of E. bicyclis in Dokdo was as high as 1,686.7 M/T wet weight, and that of E. bicyclis was 570.4 M/T wet weight. The length frequency distributions of two species were positively skewed due to the massively recruited juveniles and their subsequent growth. This means that the populations of these two species could be well maintained. Both species exhibited the significant direct regressions of stipe length, branch legth, blade length, blade width and body weight to frond length (r super(2) > 0.91, p < 0.001). This result indicates that frond length would be a good parameter for describing morphology and classifying age groups.33Nkciothe

Extensive screening of environmental stress responsive genes and theirapplication for ecosystem conservation and restoration

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