Bioremediation Of Laminaria Japonica And The Establishment Of Its Gametophyte Clones

In recent years, with the increasing of point-source pollution and large-scale mariculture in China Coast, eutrophication has become serious and red tide is developing towards high frequency and large scale.Large-scale cultivation of seaweed is one of the effective ways to absorb enutrition and reduce eutrophication. This paper has studied the bioremediation of Laminaria japonica, including bioremediation of mariculture area by Laminaria japonica in Luoyuan Bay, biopurification of Laminaria japonica on aquaculture effluents, the major nutritient uptake kinetics of Laminaria japonica, the inhibiting effect of the extract of Laminaria japonicaon to red-tide algae’s growth and the establishment of gametophyte clones. The main results were as following:1. Bioremediation of mariculture area by Laminaria japonica in Luoyuan BayCompared with the controlling area, during Laminaria japonica cultivation from March to May, the reduction percentages of DIN in the area of seaweed cultivation was up to25.48%,19.62%,44.65%respectively, and percentages of DIP was20.17%,32.00%,38.72%respectively. Among three main kinds of DIN, Laminaria japonica had the highest reduction of NH4-N. On an average, the nitrogen and phosphorus content of dry weight of Laminaria japonica were8.87%and1.68%, respectively during March to May. The fresh quality of the alga reached to the maximum of533g in mid-April. Nitrogen and phosphorus removal were51.2kg and9.84kg in one hectare of Laminaria japonica cultivation during harvest time. This algal cultivation could improve water quality and reduce concentrations of DIN and DIP in Luoyuan bay.2. The biopurification of Laminaria japonica on aquaculture effluentsThrough the establishment of circulation cooling water system, the condition of low temperature and aeration in the laboratory, individuals of Laminaria japonica proved to be efficient in removing inorganic nitrongen of effluents within the7-days experiment, achieving over98%of removal in three experimental groups and a good daily growth rate and increasing of fresh weight and blade length.3. The major nutritient uptake kinetics of Laminaria japonicaBy combination of multiple flask and the perturbation technologies, a study on the uptake kinetics of NO3-N、NH4-N、NO2-N and PO4-P in Laminaria japonica was conducted. Before test the alaga was cultured by the depletion of nitrogen or phosphorous. There were three different stages of uptaking of NO3-N、NH4-N and NO2-N for Laminaria japonica. In the first10min of rapid uptake, the maximum uptake rate of NO3-N、NH4-N and NO2-N was75.76μmol·g-1h-1、137.03μmol·g-1h-1and63.69μmol·g-1h-1, respectively, the corresponding Km was15.04μmol·g-1h-137.04μmol·g-1h-1and13.97μmol·L-1respectively. The maximum uptake rate of PO4-P was38.22μmol·g-1h-1and its corresponding Km was26.99μmol·L-1.It showed that Laminaria japonica had a good absorption effects on NO3-N、NH4-N、NO2-N and PO4-P under the depletion of nitrogen and phosphorus.4. The effects of the extracts of Laminaria japonica on the growth of red-tide algaeIn coexistence assays, dry powder, aqueous extracts, proteins, or extracts of Laminaria japonica with methanol, ethyl acetate, acetone, chloroform and petroleum ether strongly inhibited the growth of Alexandrium tamarense and Skeletonema costatumum.They were completely killed with different concentrations of various extracts.Usually, five kinds of organic solvent extract showed the strongest inhibition effect to two species of red tide algae.5. The establishment of Laminaria japonica gametophyte clonesGametophyte clone was obtained through the cultivation of Fujian Laminaria japonica gametophytes, meanwhile,comparing with static cultivation, by oscillation cultivation the SGR of male gametophytes clones increased by3.58%per-day, and the female gametophytes clones increased by3.58%,respectively. After the experiment, the average quality of male gametophytes clones by the oscillation culture was1.82times of the staticculture and, the female gametophytes clones was2.15times.