灵昆岛东滩潮间带大型底栖动物功能群及营养等级构成

The trophic functional groups and trophic levels of the macrobenthic community at the east tidal flat of Lingkun Island

2003年11月至2004年8月,在温州湾的灵昆岛东滩针对大型底栖动物群落进行了取样调查,利用调查数据进行功能群和营养等级构成研究。共得到大型底栖动物33种,隶属7门8纲21科,主要为软体动物、节肢动物甲壳类和环节动物多毛类。其中,高潮带25种,中潮带30种,低潮带14种。Margalef物种丰富度指数和Shannon-Weiner多样性指数均表现为:高潮带>中潮带>低潮带;Pielou均匀度指数和Simpson优势度指数表现为:高潮带<中潮带<低潮带。定性取样得到的浮游生物食者4种,植食者12种,肉食者8种,杂食者7种,碎屑食者2种,定量取样得到的分别为:3,8,5,3种和2种。定量取样获得数据中各个功能群种类数和密度季节间差异均不显著,不考虑季节变化因素肉食者和植食者密度在潮带间存在差异,杂食者和植食者种类数在潮带间存在差异,其他功能群密度和种类数数据在潮带间的差异不显著。研究显示了功能群的生境梯度变化,高潮带主导的功能群为肉食者,植食者和浮游生物食者;中潮带主导的功能群为肉食者和浮游生物食者;低潮带主导的功能群为肉食者,这些变化反映了不同潮带营养等级构成和食物来源的差异,由于生境中能提供的植物沿着高潮带,中潮带和低潮带方向递减,至低潮带未发现植食者;且由于中潮带的生境最为复杂,其功能群的构成也最为复杂;3个潮带的碎屑食者数量比较稳定。大型底栖动物群落与其食物来源一起共有4个营养等级,其中大型底栖动物占据了第2、3、4级,第1级主要碎屑、浮游生物和植物,第2级包括了碎屑食者、浮游生物食者和植食者,第3级主要是杂食者,第4级是肉食者,各个营养级、食物来源之间构成一张复杂的食物网。

From Nov. 2003 to Aug. 2004, macrobenthic assemblages were investigated seasonally at the east tidal flat of Lingkun Island, Wenzhou Bay. A total of 33 taxa, including 21 families, 8 classes and 7 phyla, were found. Most of them were mollusks, crustaceans and polychaetes. The species numbers found at three tidal fiat （high, middle and low） were 25, 30 and 14. The average value of Margalef＇s and Shannon-Wiener＇s indices were the highest at high tidal flat （2.26 and 2.04）, following by middle （2.04 and 2.10） and low （1.02 and 1.50） tidal fiat. The average values of Pielou＇s and Simpson＇s dominance indices had the Opposite trend： high （0.89 and 0, 14） 〈 middle （0.85 and 0.16） 〈 low （0.96 and 0.25 ） tidal flat. The species belonged to five different trophic functional groups： Phytophagous （12）, Camivorous （8）, Omnivorous （7）, Planktophagous （3） and Detritivorous （2） in qualitative samplings. Then 3, 8, 5, 3 and 2 kinds of species belonged to Planktophagous group, Phytophagous group, Carnivorous group, Omnivorous group and Detritivorous group respectively in quantitative sampling. The density and species number of each functional group did not display seasonal variation by the two-way ANOVA method. Without regarding the seasonal variation, density of the Phytophagous group （54.00 ±1.41, 32.00 ±6.32 and 0 respectively to high, middle and low tidal flat） and Camivorous group （54.00 ±4.76, 64.50 ±4.65 and 22.00 ±3.37 respectively to high, middle and low tidal flat） had distinct difference among the different zones of tidal fiat, the species number of the Phytophagous group （5.25 ±0.25,3.75 ±0.48 and 0 respectively to high, middle and low tidal fiat） and Omnivorous group （ 1.25 ±0.48, 1.75 ±0.25 and 0.25 ±0.25 respectively to high, middle and low tidal fiat） had distinct difference among the different zones of tidal fiat. The results show that there was variation of functional groups among habitats. The Planktophagous group, Phytophagous group and Camivorous group were the primary components of the macrobenthic community at high tidal fiat, the Planktophagous group and Camivorous group are the primary components of the macrobenthic community at middle tidal fiat, then the Camivorous group was the primary component of the macrobenthic community at low tidal fiat. The change of components of macrobenthie community reflected the change of food source in different zones of tidal fiat. Because the plants decreased in the gradient from high, middle to low tidal fiat, the Phytophagous group decreased along the direction of high, middle and low tidal fiat. There was no Phytophagous group at low tidal fiat. The density and species number of the Detritivorous group was similar in the three zones of the tidal fiat. In conclusion, there were 5 functional groups in the macrobenthie community including the Planktophagous group, Phytophagous group, Detritivorous group, the Omnivorous group, and the Camivorous group; there were 4 nutrition levels at the macrobenthic community with the food resource, then the maerobenthos were the second, third and fourth level in the system, the first level included the dross, plankton and plant, the second level included the Planktophagous group, Phytophagous group and Detritivorous group, the third level was the Omnivorous group, the fourth level was the Camivorous group; which implies the tidal fiat with a complicated food web.