Foundational Studies on Resource Investigation and Ecological Restoration of Eelgrass in Typical Bays in Shandong
|School||Graduate School , Chinese Academy of Sciences ( Institute of Oceanography )|
|Keywords||Eelgrass Ecological characteristics Restoration Bivalve molluscs Biodepostion|
Methods of morphology and experiment ecology were adopted to investigateecological characteristics of the seagrass meadows occurring in coastal water inShandong; and several eelgrass ecological restoration methods were tried. Apreliminary understanding of the coastal Zostera seagrass resources status was gained,and several effective seagrass recovery methods were obtained. The main results aresummarized as follows:There were five species of seagrasses in inshore areas of Shandong totally, whichbelong to two genera. The five species were Zostera marina L., Zostera caespitosaMiki, Zostera japonica Ascherson&Graebner, Phyllospadix iwatensis Makino, andPhyllospadix japonicus Makino.Results showed that average temperature of surface seawater in Swan Lake,Sangou Bay, and Qingdao Bay was14.7℃,16.3℃and15.1℃from September2010to September2011, respectively. The average spacing density of Zostera marina inthese three areas was438ind/m~2,613ind/m~2and618ind/m~2, respectively; and averageheight of the seagrass was11.73±2.83~158.53±33.61,18.80±4.13~87.60±20.68,and27.77±5.51~114.80±25.86cm, respectively. The average biomass of aerial partswas0.61~15.95,0.76~5.31, and0.93~7.30g/ind, respectively. The average biomass ofunderground parts was0.34~4.66,0.39-2.89, and0.46~2.24g/ind, respectively. Theannual average biomass of aerial parts and underground parts was267.18~6986.10,471.19~3252.58,578.04~4508.52; and150.67~2042.54,242.34~1776.47,283.46~1388.44, respectively. Changes of biomass and height of eelgrass were related to temperature of sea water.Contents of carbon, nitrogen and phosphorus in different parts of eelgrass variedseasonally. Annual average contents of carbon in underground stem, aerial stem andleaf of eelgrass were32.68±1.27,33.78±3.06,37.01±1.86%, respectively,similarly annual average contents of nitrogen were1.62±0.63,2.79±0.81,3.10±0.81%, respectively; while annual average contents of phosphorus were0.28±0.04,0.51±0.10,0.48±0.07%, respectively. Variation in contents of carbon, nitrogen andphosphorus in surface sediment associated with organic matter due to degradation anddetachment of eelgrass. The sediment under the eelgrass bed mainly consisted of sandand mud. Concentrations of nitrites, phosphates, ammonia nitrogen and nitrates wereconformed to the standard of class seawater.Macrobenthos in seagrass beds of Swan Lake and Sangou Bay were investigated.66species were identified in Swan Lake, including37species of polychaetes,13species of molluscs,15species of crustaceans, and one specie of echinoderms.39species were identified in Sangou Bay, including23species of polychaetes,6speciesof molluscs,8species of crustaceans, and one specie of others. The dominant speciesin these two areas are both annelid polychaetes, two other main groups werearthropods and molluscs.Eelgrass was transplanted through several methods, including direct planting ofrooted shoots, planting of rooted shoots tied on stones with cotton thread, planting ofrooted shoots in mud pot, planting of rooted shoots using planting devices. In addition,depth experiments were carried out in Ailian Bay and Jiaozhou Bay. Results showedthat these eelgrass-transplanting methods were effective; Growth and survival oftransplanting eelgrass were monitored after planting. The rate of survival could reachto more than85%. The depth experiments showed that the suitable actual depth fortransplanting eelgrass was4meter. Considering of the4meter tide, the depth incoastal waters that was suitable for eelgrass transplanting was8meter. Laboratorysimulation experiment showed that the rate of germination were22%to26%. But the shoots could not survival longer than6months. Therefore, eelgrass restoration byseed breeding is difficult and needs further research.Biodeposition and ecological effects of several species of bivalves in JiaozhouBay were studied. The cultured bivalves were including Chlamys farreri, Argopectenirradians and Mytilus galloprovincialis. The characteristics of water environment, therates of biodeposition, and the contents of carbon, nitrogen, phosphorus and heavymetal of biodeposits were measured.