中国经历了大量的沿海填海和河流筑坝。这些变化有可能影响远缘鱼类在海洋和淡水之间的迁移,但是这些鱼类的组成以及障碍对它们在中国运动的影响很少受到关注。我们清点了远缘鱼类的种类组成和分布,以及障碍对它们的影响,在香港特别行政区,中国南方。使用手网对鱼类进行了调查,辅以投射网和单通浮潜调查,在三个地区的24条沿海小溪中。在雨季和旱季多次进行了调查,以说明季风热带气候。收集了二十八条透水鱼,主要是虾虎鱼,占主要淡水鱼总丰富度的一半以上(53%);从文献记录中得知另外四个物种。雨季的横向丰富度增加了48%,当遇到所有物种时。丰富度在溪流之间变化很大,从最多17(2流的多样性热点)到无(3流)。最广泛的泛鱼是Glossogobiusgiuris(发生频率为71%),其次是Mugil头颅(58%的发生率)和拔牙(50%的发生率)。剩下的25条透水鱼发生在不到一半的溪流中;12种被限制在一条溪流中,可能受到局部威胁。整个香港特别行政区的杂物组合存在明显的空间差异,尽管范围有限(1114平方公里),被调查的溪流的接近程度,以及大多数物种的广泛地理分布。区域物种组合受到局部栖息地特征的影响,有和没有大的区域之间有明显的区别,快速流动,和高度含氧的溪流。溪流屏障(堰:高0.3-8.7m)的存在并不影响物种组合的空间格局,虽然,平均而言,在堰阻塞的河流中,透水丰富度较低(4.0与无阻塞溪流中的6.9种)。总的来说,18种被限制在无阻碍的溪流或堰下方的部分,而其余10种都在堰上方和下方记录。只有斑驳的鳗鱼(安圭拉marmorata)和虾虎鱼(Stiphodonmultisquamus)能够在2m以上升堰。尽管对每条河流的下游至少400m进行了采样,在13条被堰阻塞的溪流中,有12条被限制在前300m。值得注意的是,香港特区32个透脉物种的总数超过了中国大陆已知的19个,强调需要进一步研究透水鱼类的组成和保护状况。
China has experienced substantial coastal reclamation and damming of rivers. These changes have the potential to impact migrations of diadromous fishes between the sea and fresh waters, but the composition of these fishes and the impacts of barriers to their movement in China have received little attention. We inventoried the species composition and distribution of diadromous fishes, and the impacts of barriers on them, in the Hong Kong Special Administrative Region (HKSAR), southern China. Fish assemblages were surveyed using hand-nets, supplemented by cast-netting and single-pass snorkel surveys, in 24 small coastal streams across three regions. Surveys were undertaken on multiple occasions during the wet and dry seasons to account for the monsoonal tropical climate. Twenty-eight diadromous fishes were collected, mostly gobies, amounting to over half (53%) of the total richness of primary freshwater fishes; four additional species are known from literature records. Diadromous richness was 48% greater during the wet season, when all species were encountered. Richness varied substantially among streams, from a maximum of 17 (2 streams that were diversity hot spots) to none (3 streams). The most widespread diadromous fish was Glossogobius giuris (71% frequency of occurrence), followed by Mugil cephalus (58% occurrence) and Eleotris oxycephala (50% occurrence). The remaining 25 diadromous fishes occurred in fewer than half of the streams; 12 species were confined to a single stream and may be locally threatened. There were conspicuous spatial differences in diadromous assemblages across HKSAR, despite its limited extent (1114 km2), the proximity of the surveyed streams, and the broad geographic distribution of most species. Regional species assemblages were influenced by localized habitat characteristics, with a noticeable distinction between areas with and without large, fast-flowing, and highly oxygenated streams. The presence of in-stream barriers (weirs: 0.3-8.7 m high) did not affect spatial patterns in species assemblages, although, on average, diadromous richness was lower in weir-obstructed streams (4.0 vs. 6.9 species in unobstructed streams). In total, 18 species were confined to unobstructed streams or sections below weirs, whereas the remaining 10 species were recorded both above and below weirs. Only the mottled eel (Anguilla marmorata) and a goby (Stiphodon multisquamus) were able to ascend weirs over 2 m. Although at least 400 m of the lower course of each stream was sampled, diadromous fishes were confined to the first 300 m in 12 of the 13 weir-obstructed streams. Remarkably, the tally of 32 diadromous species in HKSAR exceeds the 19 known from mainland China, highlighting the need for further research on composition and conservation status of diadromous fishes.