The Study On Marine Meiofafuna In The Human-distrubed Sandy Intertidal Shores Of Qingdao

The meiofauna and its sedimentary environment were investigated seasonally in a one-year period in three bathing beaches of Qingdao (No.1, 2 and 3 bathing beaches) which were subject to various degree of human disturbance. The sampling dates were chosen seasonally in March (spring season in Qingdao), July (summer), October (autumn), 2010 and in January (winter), 2011. Besides these three sampling locations, an additional samples collection was taken in June, 2010 in the outfall zone of the No.1 bathing beach. The meiofauna studies mainly focused on the spatial-temporal changes of faunal abundance, biomass and group composition. Meanwhile, the studies of sedimentary environments were to measure the salinity, temperature, dissolved oxygen and pH in situ and to measure the particle size of sediment, chlorophyll level and organic content back in laboratory. To study the effects of organic-enrichment on the meiofauna, a combination study of field survey and laboratory microcosm experiment was carried out in April, 2010.There were three sections in this thesis which were:1.Sedimentary environment of the human-disturbed sandy intertidal shores;2.Spatial-temporal changes of meiofauna abundance and biomass in the human-disturbed sandy intertidal shores ;3.Effect of organic-enrichment on sandy beach meiofauna, field study and laboratory microcosm experiment.The results of the sedimentary environmental study showed: three sampling locations were all sandy beaches; and the major components of all sediments were fine sand. The sediments were well sorted; the values of MDφ(between 1.985 and 2.434) were about to be the same; and the values of Ski always closed to zero. The measurement results of the sedimentary particle size did not show obvious seasonal or spatial variations. In No.2 and No.3 bathing beaches, the annual changing trends of chlorophyll-αwere similar with highest values occurred in summer. However, in No.1 bathing beach, the highest value of chlorophyll-αappeared in autumn season. The chlorophyll-αlevel of the No.1 bathing beach in autumn (post-bloom period of the green tide) was found extremely high than other seasons and sampling locations, which may be caused by the dramatically increasing of the stock of green algae (i.e., green algae bloom). In autumn, No.2 and No.3 bathing beaches seemed not to be affected by green tides, however, the chlorophyll-αlevels in summer (bloom period of the green tide) of those two locations were highest seasonally, this perhaps indicated that chlorophyll-αhas strong relationship with green tide. Besides spring and summer season, the chlorophyll-αdecreased continuously since autumn to winter in No.2 and No.3 bathing beaches, suggesting that the chlorophyll-αlevel was affected by temperature and solar radiation intensity. Among three bathing beaches, the changing trends (continuously decreasing along seasons) of TOM were very closely similar to each other: the values of TOM were all fairly high in spring season in three sampling locations, but not significant different to other three seasons. This may be caused by the low decomposition rate in winter temperature and accumulation of organic matter. In the additional one-off study in the outfall zone of the No.1 bathing beach in June, 2010, the value of the chlorophyll-α(mean: 0.646 mg/kg) was statistically close to the summer value (mean: 0.937 mg/kg), and they are not statistically different to each other (one-way ANOVA, F_1,11 = 2.687, p = 0.129).The studies on meiofaunal abundance and biomass shows that, in No.1 and 3 bathing beaches, the changing patterns of the meiofaunal abundance in one year period were similar to the ones of the meiofauna biomass: abundance and biomass was positive correlated. In the No.1 bathing beach, both highest abundance and biomass occurred in summer, then decreased continuously since summer to winter; differently, in the No.3 bathing beach, the sharp turning down or up of both abundance and biomass happened along every season. However, the fluctuation patterns of No.2 bathing beach were slightly different to other two bathing beaches: the abundance and biomass was negative correlated, but the values of them were fair stable along four seasons. The two-way crossed ANOVA for meiofaunal abundance comparison among sampling locations (location variability: three bathing beaches) and seasons (seasonality: four seasons) showed that there were no significant effect of the sampling locations on the meiofaunal abundance (two-way ANOVA, p = 0.075); and no significant effect of the seasons on meiofaunal abundance (two-way ANOVA, p = 0.902) as well. But, significant effects of the interaction (location variability x seasonality) on the meiofaunal abundance (two-way ANOVA, p = 0.002) were detected.The Pearson correlation analysis showed that the meiofauna abundance was negative correlated to chlorophyll a; the biomass was positive correlated to salinity, and negative correlated to temperature. Thus, furthermore graphs of seasonal variations between the abundance and chlorophyllαamong three sampling locations were drawn: from summer to autumn, meiofaunal abundance has a dramatic decreasing only in No.1 bathing beach, this differ to other two bathing beaches in same period. These indicate that some special events (human disturbance, such as tourism and the bloom period and post-bloom period of the green tide) did happen in the No.1 bathing beach during the summer and autumn seasons which may cause the increased chlorophyll level increased and decreased meiofaunal abundance.The meiofauna group compositions had been analyzed. The results showed that they did change seasonally and spatially. Nematoda was the most dominant group, and then, Copepoda and Polychaeta was another two main component groups in each season and sampling location. Beside these three meiofauna groups, Ostracoda, Cnidaria, Cumacea, Amphipoda, Kinorhyncha, Tardigrada, Turbellaria, and Bivalvia were found. By the comparison of meiofauna compositions among three bathing beaches, the composition trends were similar to each other. The vertical distributions of the meiofauna were similar to each other seasonally and spatially, most meiofauna groups with large percentage were found in (0-4) m layers, the abundance decreased with the increasing of the sampling depths. In winter season of the No.1 and 2 bathing beaches, the meiofauna abundance in (0-4) cm layers dramatically decreased. This indicated that the cold temperature has the direct effect on meiofauna, and pushes the meiofauna migrate downwards to maintain heat. However, the phenomenon did not occur in the winter of the No.3 bathing beach. And, the vertical distribution in the outfall zone of No.1 bathing beach was absolutely different to other studies, the larger meiofauna abundances always were found from deeper depths. This maybe caused by human-disturbance (i.e., daily run-off from outfall): the strong run-off movement reduced the surface salinity; and force the meiofauna migrate downwards.The last section of the thesis was a summary about the organic-enrichment study based on both the laboratory microcosm experiment and corresponding field study. The key hypothesis of this study is to examine whether the meiofaunal abundance would be affected by the organic enrichment, and whether and how the abundance would be higher in high-organic enrichment levels other than in low-organic enrichment levels. To examine this, a 21-days laboratory microcosms experiment was set up. N/C ratios were investigated as well. The organic content of the sediments is a decisive factor and plays a key role in meiofaunal density and diversity. Among three different organic content levels (high-organic level, low-organic level and control/reference level), both of meiofauna and nematode abundance was significantly different. However, the abundance was highest in non-organic matter added (control/reference) treatments; comparing with other groups, i.e., the low-organic and high-organic matter addition treatment results, a fair decrease in the total meiofaunal and nematode abundances was obtained and the number of taxa was greatly reduced. However, only the decrease in low-organic matter groups was statistically different with non-organic matter groups (control groups). Overall, the results of the thesis showed that not only do meiofauna abundances vary seasonally, but also does the group composition. No.1, 2 and 3 bathing beaches were all human-disturbed areas, and No.1 bathing beach was affected by the human disturbance mostly in tourism seasons, nematode was the most dominant meiofauna group and least affected.Which abiotic and/or biotic factors control meiofauna communities most is still not very clear because of the lack of sufficient data to come up with an answer. But, by the evidence from this thesis, the spatial and temporal change of meiofaunal abundance was supposed to be controlled by environmental factors of Chl-α, salinity and temperature mostly, and could be affected by human disturbance.