Zostera marina is the only seagrass species whose seeds have been successfully used in large‐scale restoration. Although progress has been made in refining Z. marina restoration protocols, additional information on Z . marina seed physiology is necessary as the science of seagrass restoration evolves. We tested the germination rates of Z. marina seeds under different relative humidities and temperatures for different periods of time. Z. marina seed moisture content (MC) and germination rates were also tested when seeds were exposed to a temperature of 25°C and relative humidity of 50%. Z. marina seeds suffered higher mortality when exposed to lower relative humidity and higher temperature for longer period of exposure time. A significant negative correlation was detected between seed germination rate and MC. Z. marina seeds are sensitive to desiccation exposure and long periods of exposure to air should be prevented to minimize seed mortality when seeds are used in restoration projects.
Abstract The coast of the Yellow Sea in China, like many other temperate coastal zones, has been experiencing a dramatic decline in the abundance of seagrass. Intensive efforts have been made to restore seagrass communities along the coast to restore the function of the coastal ecosystem. Transplanting adult Zostera marina shoots is labor‐intensive, time‐consuming, expensive, and detrimental to donor beds; thus, restoring seagrass communities through the use of seeds is highly valued in current, large‐scale restoration trials. In this study, an effective method for collecting, processing, and storing Z. marina seeds was developed. From 2009 to 2013, respectively, 122,000, 421,000, 364,000, 1,041,000, and 1,091,000 seeds were successfully collected. Two‐way analysis of variance ( ANOVA ) showed the interaction between salinity and temperature significantly affected the cumulative germination rate (CGR) ( p < 0.01) during the storage period and the viability ( p < 0.01) of seeds after storage. The germination rate after storage was significantly affected by salinity and temperature ( p < 0.01). The highest viability (89.8 ± 1.0%) and germination rate (75.6 ± 4.5%) were found among seeds stored at 4°C and a salinity of 44.5 psu for 7 months. The cost for planting 1 ha of sea bottom with Z. marina seeds ranged from $2,613 to $80,900 depending on the seeding density and seed loss during storage. The average cost per Z. marina seed in this study was $0.00586.
This paper studied the dynamics of reproductive allocation (RA) of Sargassum thunbergii during its sexual reproductive season and the related environmental factors at the Taiping Cape of Yellow Sea. The sexual reproduction of S. thunbergii initiated in early June, peaked in mid July when the sea water temperature was about 22 degrees C (the mean proportion of biomass allocated to reproductive organs on July 19 was 76.7%), and ended in late August. The RA had a significant linear correlation with the average length of thallus branches (r = 0.855, P < 0.01). The thalli with a length less than 10 cm showed a lower RA in the whole sexual reproductive season, while the thalli longer than 10 cm had a RA up to averagely 70.0% at the peak maturing stage. UNIANOVA analysis showed that both tidal level and wave strength had significant effects on the RA of S. thunbergii (tidal level: F = 175.62, P < 0.01; wave strength: F = 95.35, P < 0.01), and there was a significant interaction between tidal level and wave strength (F = 9.14, P < 0.05). The sizes of the effects were in the order of tidal level > wave strength > tidal level x wave strength.
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