The Ecological And Morphological Study Of Macrobenthos In The Intertidal Zone Of Qingdao Cove

The work of this graduation thesis were partly based on the macrobenthic samples sampled in January, March, May, July, September, and November,2011 in 6 sampling sites in the intertidal zone of Qingdao Cove. The following research contents, including species composition, dominant species, abundance & biomass, biodiversity, and community structure were discussed in the ecology part of this thesis. Morphological research of Capitella capitata and Rhynchospio asiatica were elaborated in the second and the third part. The main results are as follows:In this research, a total of 190 species, including 11 macrobenthic groups were identified. They were Coelenterata, Platyhelminthes, Nemertinea, Polychaeta, Oligocheata, Sipuncula, Mollusca, Arthropoda, Pycnogonida, Echinodermata, and Chordata. Polychaeta, Arthropoda, and Mollusc made up some 94% percents of the total species numbers in every months, leaving only 6% percents for other groups.The dominant species of Qingdao Cove is mainly Polychaetes and Molluscs, like C. capitata, R. asiatica, Umbonium thomasi, and Ruditapes philippinarum. The results of Index of Relative Importance (IRI) and Dominance Index (Y) are similar. Species with larger individuals are more likely to appear in a front position in IRI results, while species with high abundance are more likely to appear in a front position in Y results.The average abundance and biomass of macrobenthos in Qingdao Cove is 36275 ind./m2 and 351.130 g/m2, respectively. Compared to other groups, Polychaetes are the most abundant ones; while Molluscs have the highest biomass, except July,2011.The content of organic carbon in high intertidal zone is higher than middle and low intertidal zone in each months, which is in accordance with the results evaluated from Shannon-Wiener diversity index (H’). When comparing among different months, the seasons of reproduction of some species with great abundance, rather than the content of organic carbon, is the main factors that can affect the value of H’.3 macrobenthic community groups could be identified at 43% similarity level according to CLUSTER, based on the average abundance of 6 sampling sites in six months. One group contains all six months of the two sampling sites in high intertidal zone, another group contains several months of the two sites in low intertidal zone, the third group contains the rest months in low intertidal zone and all six months in middle intertidal zone. The results show that, there are obvious differences among macrobenthic communities in high, middle, and low intertidal zones, while the changes of communities in the same tidal zone in different months are relatively small.Based on the present/absent of eyespots, the specimens of C. capitaia in Qingdao Cove can be divided into two sibling species. The proportions of the two species are 95.4% and 4.6%. Due to the average thorax breadth, all 12 months of C. capitata can be diviede into two periods:from June to November, and from December to May of the next year. Average breadth of the former period is smaller, and has a relatively concentrated distribution. Breadth of the latter is larger, and has a relatively scattered distribution. Based on the relationship between breadth and thorax setae types of C. capitata, all C. capitata specimens with eyespot were considered to be one species, and the linear relation shows the pattern that thorax setae types magnify with the magnifying of thorax breadth.The reproductive peak of C. capitata from Qingdao Cove is from May to June. Except a few months (September & October), there are no obvious reproductive events in most other months. To some extent, the proportion of male individuals can reflect the average growth level of the C. capitata population. The C. capitata population may decide the reproductive time by regulate and control the proportion of male individuals.By now, altogether 10 Rhynchospio species were published. Adult morphology was described and string diagram was draw in this thesis. Compared to the recorded Type Species, and based on the data of body length, number of setigers, thorax breadth, and the latitude data, the Rhynchospio species from Qingdao Cove were identified as R. asiatica Chlebovitsch, 1959, which was first reported in China. The international research about Rhynchospio is quite a few compared to other species. Taxonomy, activity and ecology are three major research fields of this Genus. Due to the limitations of morphology, the scholars are seeking for new morphological features or turning to molecular methods for the research of taxonomy. In this thesis, living specimens were observed to elaborate the swing rules of cilia on the dorsal of this species and to reveal its biological effects. It can be inferred that the swinging of dorsal cilia has important influences on the special reproduction rules of Rhynchospio.