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Li W.-T.,Pusan National University | Li W.-T.,Ocean University of China | Kim Y.K.,Pusan National University | Park J.-I.,Pusan National University | And 4 more authors.
Ecological Engineering | Year: 2014

Significant losses in seagrass coverage have been reported worldwide, and thus efforts are under way to restore disturbed seagrass habitats. Unfortunately, rates of seagrass restoration success through transplantation remain quite low, and inappropriate transplant times may be one cause of the low success rates. To determine suitable seasons for transplanting eelgrass, transplantation experiments were conducted seasonally. After each transplantation trial, shoot density, chlorophyll content, shoot morphology, and productivity of transplants and reference plants were monitored at 2-4-week intervals for approximately 3 months. All eelgrass transplants had disappeared by the end of the summer transplantation trial, whereas transplant density increased most rapidly in the fall transplantation. High water temperature in summer appeared to be a primary seasonal stress in eelgrass meadows, causing high transplant mortality. Results for shoot morphology, physiology, and growth of transplants indicated that those planted in summer suffered the most severe transplanting stress, whereas those planted in fall experienced the least stress. Accordingly, summer transplantation for eelgrass restoration should be avoided in areas where summer water temperatures are greater than 25. °C. Because transplants planted in fall exhibited the highest expansion of shoots and suffered the least transplant stress, the optimal season for eelgrass transplantation is likely to be fall, just after the high water temperature period. © 2014 Elsevier B.V.


Park J.-I.,Marine Eco Technology Institute | Son M.H.,Marine Eco Technology Institute | Kim J.B.,Marine Environment Research Division | Lee K.-S.,Pusan National University
Ocean Science Journal | Year: 2014

Phyllospadix japonicus is an abundant surfgrass that thrives mainly along the exposed rocky shores of Northeastern Asia. On the eastern coast of Korea, surfgrass populations have been adversely affected by increasing human pressures. We developed a seeding method using an artificial reef for the restoration of P. japonicus. In January 2005, we planted P. japonicus seeds on the lower part of coarse hemp-plant brush that was embedded densely on the concave surface on the top of artificial reefs. The reefs were then installed on an exposed rocky shore. To evaluate the feasibility of this seed-based surfgrass restoration technique, we monitored the seedling/shoot density and morphological characteristics of the shoots over a 2-year period. Seedlings began to emerge within the first month after seeding, reaching densities of up to 275.0 shoots m-2 by April 2005. After an initial decline, shoot density increased through the production of lateral shoots, and densities of up to 997.1 shoots m-2 were observed by the end of the experiment. Shoot height, the number of leaves, and leaf width rapidly increased during the first year after seeding, whereas the number of rhizome internodes and rhizome length rapidly increased during the second year. The P. japonicus shoots exhibited approximately 63.4 mm of rhizome elongation during the study period. Because seeded P. japonicus on the artificial reefs were successfully established at the study site, this seeding method using an artificial reef may offer an effective approach to restoring surfgrass habitat. © 2014, Korea Ocean Research & Development Institute (KORDI) and the Korean Society of Oceanography (KSO) and Springer Science+Business Media Dordrecht.


Park J.-I.,Marine Eco Technology Institute | Kim J.B.,Marine Environment Research Division | Lee K.-S.,Pusan National University | Son M.H.,Marine Eco Technology Institute
Ocean Science Journal | Year: 2013

To select the optimal site for the restoration of seagrass habitats in the Taehwa River estuary, we transplanted the eelgrass Zostera marina to three potential candidate sites in March 2007 and monitored the transplanted seagrass and associated environmental factors for six months. In all three sites, the transplanted seagrasses exhibited no initial morphological loss due to transplanting stress. The transplanted seagrass communities at sites 2 and 3 showed more than a 180% increase in density over the entire survey period. In contrast, despite a density increase in the first month after transplantation, most of the transplanted seagrasses at site 1 died. This may be due to the large decrease in underwater irradiance reaching the seagrass leaves at site 1 for two months during June and July, which fell below the level of compensation irradiance. The growth rate and size of the seagrass shoots were also larger at sites 2 and 3 compared with site 1. This is probably due to higher nutrient concentrations in the sediment pore water at sites 2 and 3 compared with site 1, although water depth, salinity, and the nutrient concentrations in the water columns from the three sites were similar. Therefore, for the restoration of seagrass habitats in the Taehwa River estuary, sites 2 and 3 were preferable to site 1 as transplantation sites. © 2013 Korea Ocean Research & Development Institute (KORDI) and the Korean Society of Oceanography (KSO) and Springer Science+Business Media Dordrecht.


Kim J.B.,Marine Environment Research Division | Lee W.-C.,Marine Environment Research Division | Lee K.-S.,Pusan National University | Park J.-I.,Marine Eco Technology Institute
Ocean Science Journal | Year: 2013

To examine the growth dynamics of eelgrass, Zostera marina, in the intertidal zone of Seomjin Estuary, Korea, we surveyed environmental factors such as water temperature, underwater irradiance, tidal exposure, and nutrient concentrations in the water column and sediment pore water in relation to the shoot density, biomass, morphological characteristics, and growth of Z. marina inhabiting the upper and lower intertidal zones. The survey was conducted monthly from January 2003 to December 2004. The water temperature of the two areas displayed seasonal fluctuations. Underwater irradiance was significantly higher in the upper intertidal zone than in the lower intertidal zone. Tidal exposure was also markedly longer in the upper intertidal zone than in the lower intertidal zone, whereas tidal exposure was highest in the spring and lowest in the summer in both areas. Water column NH4 + and sediment pore water NO3 -+NO2 - concentrations were significantly higher in the upper intertidal zone than the lower intertidal zone. The eelgrass shoot density, biomass, morphology, and leaf productivity were significantly higher in the lower intertidal zone than in the upper intertidal zone. Both areas displayed a clear seasonal variation depending on changes in water temperature. However, leaf turnover time was significantly shorter in the upper intertidal zone than in the lower intertidal zone, with a higher turnover rate in the upper intertidal zone. Compared to the seagrasses in the lower intertidal zone, those in the upper intertidal zone showed more effective adaptations to the stress of long tidal exposure through downsizing and increased turnover time. These results suggest that tidal exposure, coupled with desiccation stress, can be a limiting factor for seagrass growth in the intertidal zone, along with underwater irradiance, water temperature, and nutrient availability. © 2013 Korea Ocean Research & Development Institute (KORDI) and the Korean Society of Oceanography (KSO) and Springer Science+Business Media Dordrecht.


Park J.-I.,Marine Eco Technology Institute | Lee K.-S.,Pusan National University | Son M.H.,Marine Eco Technology Institute
Ocean Science Journal | Year: 2014

To determine the optimal storage method and longest possible storage period of Phyllospadix japonicus seeds, we examined post-storage germination rates using different storage methods and periods for P. japonicus seeds harvested in Korean coastal waters. P. japonicus seeds are classified as recalcitrant seeds with an average moisture content of 45.4%. Germination rates of P. japonicus seeds stored in seawater at 4 °C, seawater at room temperature with air supply, and an aquarium with continuous seawater circulation ranged from 35.0% to 43.5%, whereas seeds stored in seawater at 30°C, a refrigerator at -20°C, and a desiccator at room temperature did not germinate. Seeds stored at 4°C maintained germination rates of 72.5~73.0% until 30 days of storage, but showed rapidly decreasing germination rates after 60 days and no germination after 180 days. Since few studies have investigated seed storage of P. japonicus, these results will serve as useful data for seed-based P. japonicus habitat restoration. © 2014 Korea Ocean Research & Development Institute (KORDI) and the Korean Society of Oceanography (KSO) and Springer Science+Business Media Dordrecht.


Kim J.-H.,Pusan National University | Park S.H.,Pusan National University | Kim Y.K.,Pusan National University | Kim S.H.,Pusan National University | And 3 more authors.
Ocean Science Journal | Year: 2014

Zostera caulescens is an endemic seagrass species in Northeastern Asia. Estimated distributional area of this species is approximately 1–5 km2 on the coasts of Korea. Because Z. caulescens has a very limited distribution, the growth dynamics of Z. caulescens is little known in the coastal waters of Korea. In the present study, we investigated the growth dynamics of Z. caulescens in relation to coincident measurements of environmental factors, such as underwater irradiance, water temperature, and nutrient availability. The study was conducted on a monotypic meadow of Z. caulescens in Uljin on the eastern coast of Korea from September 2011 to September 2012. Shoot density and biomass of Z. caulescens showed distinct seasonal variations, and exhibited strong correlations with water temperature suggesting that the seasonal growth of this species was regulated by water temperature. Shoot density and biomass rapidly decreased during the high water temperature period in summer, and thus Z. caulescens is considered a cold water adapted species like other temperate seagrass species on coasts of Korea. Biomass of photosynthetic leaf tissues on reproductive shoots was approximately 4 times higher than that on vegetative shoots. The height of reproductive shoots ranged from 1.2 m in February 2012 to 3.2 m in August 2012, whereas the height of vegetative shoots was usually less than 1.0 m. Leaf tissues on reproductive shoots probably received much more light for photosynthesis than those on vegetative shoots. Thus, reproductive shoots may play an important role in total production of Z. caulescens. © 2014, Korea Ocean Research & Development Institute (KORDI) and the Korean Society of Oceanography (KSO) and Springer Science+Business Media Dordrecht.


Kim J.-H.,Pusan National University | Kim J.-H.,Marine Eco Technology Institute | Kim S.H.,Pusan National University | Kim Y.K.,Pusan National University | And 2 more authors.
Estuarine, Coastal and Shelf Science | Year: 2016

The seagrass Zostera japonica occurs mainly in the intertidal zone and is thus exposed to widely varying environmental conditions affecting its growth and distribution compared to subtidal seagrasses. The growth dynamics of Z. japonica at its upper and lower distributional limits in the intertidal zone were investigated in Koje Bay on the southern coast of Korea to examine the environmental stresses and limiting factors on the growth of intertidal seagrasses. The shoot density and morphology, biomass, and leaf productivity of Z. japonica were measured in relation to coincident measurements of environmental factors at its upper and lower distributional limits and in an intermediate zone of the intertidal area. The mean exposure time to the atmosphere during low tide in the upper intertidal zone was approximately 1.5- and 1.9-fold longer than that in the intermediate and lower intertidal zones, respectively. Shoot density and biomass were significantly higher in the intermediate zone than at the upper and lower distributional limits. Longer emersion leading to a various of environmental stresses appeared to reduce Z. japonica growth in the upper intertidal zone, whereas interspecific competitive interactions related to irradiance seemed to affect Z. japonica growth in the lower intertidal zone. Shoot size, density, biomass, and leaf productivity were lower in the upper than in the lower zone, implying that emersion-associated stresses in the upper zone had a greater detrimental effect on Z. japonica growth than did stresses occurring in the lower zone. The productivity of Z. japonica showed strong positive correlations with air and water temperature, suggesting enhancement of Z. japonica production at higher temperatures. Thus, the predicted increases in air and water temperature associated with global climate change might have positive effects on the growth and extension in distributional range of this species. © 2016 Elsevier Ltd.

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