| 摘要: |
| 于1994年12月–1995年3月（南极夏季）期间，对南极菲尔德斯半岛卵石滩、岩石滩潮间带南极帽贝的种群数量、垂直分布进行了定点、定时、定量的调查和观察。结果表明，南极帽贝的种群数量有明显下降，分别仅为起始数量的35％和52％。卵石滩潮间带的帽贝分布于中潮区及低潮区，尤其是低潮区，且有随季节（冬季来临）向潮下带移动的趋势。岩石滩潮间带的帽贝具有类似的垂直分布特征，但其在分布带上的发生频次有很大差异，呈波动状态。在垂直岩面上，帽贝数量在低潮区的底部更为集中。讨论了导致数量变化、垂直分布的可能原因。今后有必要深入研究种群数量的时空动态及其调控机理。 |
| 关键词: 南极帽贝 种群密度 垂直分布 |
| DOI： |
| 分类号: |
| 基金项目:国家“八五”重点科技攻关项目，85-905-02号和国家南极考察委员会“八五”南极考察研究项目85-02号联合投资 |
|
| STUDIES ON THE POPULATION ECOLOGY OF THE LIMPET NACELLA CONCINNA IN THE INTERTIDAL ZONE OF FILEDS PENINSULA, ANTARCTICA—VARIATION OF POPULATION DENSITY IN SUMMER AND VERTICAL DISTRIBUTION |
|
HUANG Feng-peng1, WU Bao-ling1, XU Ru-mei2, JIANG Nan-qing2
|
|
1.First Institute of Oceanography, State Oceanic Administration, Qingdao, 266003;2.College of Life Sciences, Beijing Normal University, 100875
|
| Abstract: |
| During the summer (December 1994 to March 1995) in Antarctica, investigations at fixed stations were made into the population quantity and vertical distribution of the Antarctic limpet (Nacella concinna) on the pebble beach, rocky beach and vertical cliffs, respectively, of the intertidal zone of the Fildes Peninsula, Antarctica. On the pebble beach, three sampling zones, each 1 m wide and spaced 2 m apart, were set up; piles were driven and connected with ropes to serve as marks for sampling at the high and low tide areas. The quantities of Nacella concinna and Neptulnea sp. living in the sampling zone, the cover percentage of the algae and the distribution of benthic algae were counted and recorded for every 1m × 1m quadrats. The spatial distribution of Nacella concinna was studied by setting up 16 × 16 quadrats 0.1m × 0.1m each and the quantity was recorded. On the rocky beach one sampling zone was set up. On the cliff the vertical distribution of Nacella concinna was investigated by counting layer by layer (0.1 m) from the high to low tide areas.
An obvious drop in the population quantity of Nacella concinna on the pebble and rocky beach to 35% and 52% of its initial quantity, respectively, was found from Dec. 1994 to March 1995. The limpet on the pebble beach was distributed in the mid-tide and low-tide areas and, especially in the low-tide area, they showed a tendency to migrate towards the infralittoral zone along with the coming of winter. On the rocky beach the limpet had a similar vertical distribution, but there appeared large differences in occurrence frequency, showing a state of fluctuation. On the vertical cliffs, the limpets were even more concentrated on the bottom of the low-tide area. During the investigation, 7 or 8 Neptulnea sp. were preying upon the limpets in the sampling zone. The tendency of the variation of the quantitative distribution of the Neptulnea sp. was opposite to that of the limpets. The birds represented by Larus dominicanus prey on the limpets, which amounted to 26.9% of the food of the bird. Each bird can consume 8.63 limpets every day.
The food of the limpets consists mainly of benthic algae. Determinations were made of the chlorophyll-a content of benthic algae in the tide area where the limpets were mainly distributed. In the mid-tide area the chlorophyll-a content increased every day, the tendency of the variations in the content was opposite to that of the limpets.
The paper only reveals the quantitative variations and vertical distribution of the limpets in summer. It is necessary to make systematic investigations successively in the sampling sites to reveal the interannual variations, and the patterns of dynamics and control mechanisms.
On the rocky beach the predation of Neptulnea sp. is not seen and the quantity of Nacella concinna also drop but the percentage is slightly lower. As the predation of Nacella concinna by birds is strong, it is necessary to study and the key factor of the various lethal factors. Among the factors causing drop in quantity of population there is the factor of migration besides death. There is a tendency for the limpets on the pebble beach to migrate towards the infralittoral zone in winter. Hence, it is necessary to further study the relations between the distribution features of the limpets and environment and food, and the patterns of the migration and spread of the limpets.
Owing to different ecological environments and bottom material there may be differences in the quantitative variation and vertical distribution of Nacella concinna, in view of the fact that its density on the rocky beach is several times that on the pebble beach. Hence, it is necessary to investigate into the food habit of Nacella concinna, the quantitative variation of its ingestion of algae and the distribution of the algae. |
| Key words: Antarctic limpets (Nacella concinna), Population density, Vertical distribution |
