不同岸线植物和仔稚鱼群落特征及其与江豚分布的关系: 以长江安庆段为例

CHARACTERISTICS OF PLANT AND JUVENILE FISH COMMUNITIES ALONG DIFFERENT SHORELINES AND THEIR RELATIONSHIP WITH THE DISTRIBUTION OF FINLESS PORPOISES: A CASE STUDY OF THE ANQING SECTION OF THE YANGTZE RIVER

  • 摘要: 为了探究不同岸线植物和仔稚鱼群落特征及其与江豚分布的潜在关系, 研究在长江安庆段选取了15个典型断面, 分别进行了植物群落结构特征和仔稚鱼群落特征调查以及开展了3次江豚数量和分布的目视考察。结果表明: (1)自然岸线、抛石岸线和预制砌块岸线分别记录了126、106和89种植物, 均以草本植物为主; Ward最小方差聚类将3种岸线的植物群落分别划分成了4、4和5个群落类型, 其中益母草+芦苇+狗牙根群落、芦苇+荻+狗牙根群落及三裂叶薯+苍耳+小蓬草群落分别在自然岸线、抛石岸线和预制砌块岸线出现频率最高。(2)共采集仔稚鱼个体130005尾, 隶属于6目7科14属15种。其中自然岸线、抛石岸线和预制砌块岸线水域分别采集了15、12和13种鱼类, 三种岸线水域鱼类群落结构均以鲤科鱼类为主。䱗、鲫、鲤、陈氏新银鱼、大银鱼和间下鱵为三种岸线水域的共优势种, 子陵吻虾虎鱼为预制砌块岸线水域的特有优势种。方差分析结果表明, 自然岸线渔获物总数量和中上层鱼类种数显著高于其他两种岸线水域。(3) 3次考察累积发现观江豚135头次, 平均每次考察观察到江豚(45.00±8.66) 头次。考察发现长江安庆段江豚总体呈连续分布, 但存在明显的集中分布区域, 江豚对自然岸线水域有较为明显的偏向选择性。(4)植物群落和仔稚鱼群落和江豚分布的相关性分析表明: 植被盖度与仔稚鱼种类、数量及小型鱼类种数之间存在显著的正相关(P<0.05), 仔稚鱼种类、数量及小型鱼类物种数和数量与长江江豚的分布也均显示出显著的正相关(P<0.05)。综上推断, 江豚选择自然岸线水域作为主要栖息地可能是由于其具有较高的植被覆盖率和丰富多样的植物种类及丰富的中上层鱼类资源。

     

    Abstract: The Yangtze finless porpoise is found exclusively in the middle and lower reaches of the Yangtze River and two large river-connected lakes-Poyang and Dongting Lakes. With a considerable stretch of the natural riverbank along the Yangtze main stem replaced by artificial structures and the depletion of fish stocks, prey availability, habitat loss, and fragmentation have become the most important factors affecting the survival of the finless porpoise. To explore the structural characteristics of plant communities and juvenile fish along different shorelines and their potential relationship with the distribution of finless porpoises, we selected 15 typical sections in the Anqing section of the Yangtze River to investigate plant and juvenile fish communities. Simultaneously, three visual surveys were conducted to record the abundance and distribution patterns of the finless porpoise, along with the types ofshorelines. The results showed that: (1) A total of 126, 106, and 89species of vascular plants were collected from the natural, rock, and prefabricated masonry shorelines, respectively, with herbaceous plants being the main life form and Asteraceae, Poaceae, and Cyperaceae as the dominant families. The Ward’s minimum variance method was used to classify plant communities of the three shorelines into four, four, and five community types, respectively. The most frequent plant associations were Ass. Leonurus japonicus + Cynodon dactylon+ Phragmites australis on natural shorelines, Ass. Xanthium strumarium+ Hemarthria sibirica + Panicum bisulcatum on rock shorelines, and Ass. Ipomoea triloba+ Xanthium strumarium+ Erigeron canadensis on prefabricated masonry shorelines, respectively. (2) A total of 130005 juvenile were collected and identified, belonging to 14 genera, 7 families, and 6 orders. Among them, 15, 12, and 13species were collected from natural, rock, and prefabricated shoreline waters, respectively. The six common dominant species across the three shoreline types were Hemiculter leucisculus, Carassius auratus, Cyprinus carpio, Neosalanx tangkahkeii, Protosalanx hyalocranius, and Hyporhamphus intermedius. The endemic dominant species in the rock and the prefabricated shoreline waters was Rhinogobius giurinus. ANOVA indicated that the total number of individual and upper fish species were significantly higher in natural shoreline waters than that in the other shoreline waters. (3) A total of 135 porpoises were sighted during the three surveys, with an average of (45.00±8.66) individuals per survey. Our observations revealed that porpoises in the Anqing section of the Yangtze River exhibit a continuous distribution, with distinct areas of concentrated distribution. However, finless porpoises displayed a noticeable preference for natural shoreline waters. (4) Correlation analyses of plant communities, juvenile fish communities, and finless porpoise distribution showed significant positive correlation (P<0.05) between vegetation cover and juvenile fish species richness, as well as between juvenile fish species richness, the number of small fish, and the distribution of the finless porpoise. (P<0.05). Therefore, we concluded that high vegetation cover, plant species diversity, and the abundance of upper fish in confluence areas are key factors supporting the habitat of the finless porpoise.

     

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