FRESHWATER FISH OF THE ADDO ELEPHANT NATIONAL PARK

Summary

This study aimed to determine the distribution and relative abundance of freshwater fish in the Addo Elephant National Park. A total of 1578 fish specimens of 12 species were collected during surveys carried out in the Sundays River and four tributaries during 1996 and 1997. The redfin minnow Pseudobarbus afer comprised 81.6% of the total catch. Length frequency analysis of P. afer populations indicated recent successful recruitment in several rivers. Differences between rivers in the concentrations of dissolved and suspended solids and pH are possible reasons for different species complements. These surveys show the distribution of P. afer and Barbus aeneus in the Eastern Cape Province to be wider than previously reported. Management action is required to minimise opportunities for further establishment and spread of alien and translocated fish species and to conserve indigenous fish assemblages within the Park.     

The potential impact of a krill fishery upon pelagic fish in the Prydz Bay area of Antarctica

Summary RMT hauls taken during FIBEX in the Prydz Bay region showed a relatively high incidence of fish compared with most previous reports from the Atlantic sector. Overall, fish comprised 3.8% by number and 8.1% by weight, and these figures rose to 26.8 and 46.1%, respectively in aimed hauls over the continental shelf. Even when only hauls with>50% E. superba are considered, fish accounted for almost 1% by weight of the catch overall, and more in aimed hauls or those taken over the continental shelf. Species composition differed markedly between the continental shelf and deep water zones. Over the shelf the fish catch comprised mainly Pleuragramma antarcticum and channichthyid juveniles, while over deep water it consisted mainly of myctophids and Notolepis coatsi. These data indicate that the potentially large krill fishery in this region could affect the populations of some shelf dwelling demersal species by increasing the mortality among their pelagic juvenile stages.     

Winter spatial distribution of fish larvae assemblages relative to the hydrography of the waters surrounding Taiwan

The aim of this study was to investigate the species composition and distribution of fish larvae in relation to hydrographic conditions in the waters surrounding Taiwan Island (TI) in February 2003. In total, 242 kinds of fish larvae belonging to 127 genera and 75 families were recognized. Among these, 109 taxa were identified to the family or genus level, others to the species level. The 12 predominant types, which constituted 71% of the total fish larvae, were Engraulis japonica, Scomber sp., Diaphus spp., Benthosema pterotum, Carangoides ferdau, Embolichthys mitsukurii, Maurolicus sp., unidentified Myctophidae, Gonostoma gracile, Trichiurus lepturus, unidentified Gobiidae, and Myctophum asperum. The distribution of fish larvae showed a clear association with water masses around TI, with higher abundances and lower species richness northwest of TI where the China Coastal Current prevails, and lower abundances and higher species diversity east of TI where the Kuroshio Current dominates. Cluster analysis distinguished three station groups and four species groups, and the distribution patterns of fish larvae also corresponded to hydrographic conditions. The total abundances of fish larvae and eight of the 12 predominant taxa showed significant and positive correlations with zooplankton abundance, which suggests that food source might be a key factor determining the abundance and distribution of fish larvae during the winter.     

长江安庆新洲水域鱼类群落结构及多样性

沙洲水域环境良好,饵料资源丰富,栖息生境多样,为鱼类的生长繁殖提供了优良的生存环境。为了解长江安庆新洲水域鱼类群落结构特征,于2017年4月、7月、10月和12月对安庆江段新洲水域鱼类群落进行季节性调查。共采集鱼类64种,分属5目11科48属,其中62.5%为鲤科鱼类。以物种数和多样性指数分析群落多样性特征,结果表明新洲水域鱼类种类多样性水平较高。单因素方差分析表明,该群落多样性季节差异显著(P0.05),空间差异不明显。新洲水域鱼类群落优势种为鳊(Parabramis pekinensis Basilewsky, 1855)、鲤(Cyprinus carpio Linnaeus, 1758)、贝氏■(Hemiculter bleekeri Warpachowsky, 1887)、银鮈(Squalidus argentatus Sauvage et Dabry, 1874)和似鳊(Pseudobrama simoni Bleeker, 1864)。4种摄食功能群中,杂食性(42.19%)和肉食性(35.94%)鱼类物种数比例较高;3种生态类群中,淡水定居性鱼类占绝对优势(84.37%);3种栖息水层类型中,底层鱼类物种数比例较高,占37.50%。大型经济鱼类占总渔获物比例低(0.01%),但个体较大,因而相对重要性指数(IRI)高。总体上,新洲鱼类群落多样性和丰富度指数较高,均匀度指数偏低,个体小型化趋势明显。捕捞强度过大、水利工程建设导致的江湖阻隔及外来物种入侵是新洲水域渔业资源衰退的主要因素。由此,建议持续开展长江渔业资源监测,加强长江干流沙洲水域渔业资源保护。     

Lipids of the notothenioid fishes Trematomus spp. and Pagothenia borchgrevinki from East Antarctica

The notothenioid fishes Trematomus pennellii, T. newnesi, and T. bernacchii had 5–15% skeletal lipid, as percent dry weight, and this comprised 6–8% of the total body lipid. Trematomus hansoni and Pagothenia borchgrevinki had 2–4% skeletal lipid, which comprised 1% of total body lipid. Triacylglycerol was the major lipid class present in all tissues of all fish analyzed (up to 89% of total lipid), with minor components including sterol, phospholipid and wax esters. Monounsaturated fatty acids comprised 38.3–58.0% of the total fatty acids, and included primarily oleic [18 : 1(n-9)] and palmitoleic [16 : 1(n-7)] acids. Polyunsaturated fatty acids comprised 19.1–40.0% of the total fatty acids and included primarily eicosapentaenoic acid [20 : 5(n-3)] and docosahexaenoic acid [22 : 6(n-3)]. These five notothenioid fishes, which include benthic, benthopelagic, and cryopelagic species, are lower in lipid than other important Southern Ocean fishes (such as the Patagonian toothfish) and are estimated to be negatively buoyant. These data will be of use to research groups presently using signature lipid methodology. Accepted: 5 April 1999     

Seasonal vertical distribution and diel migration of zooplankton in a temperate stratified lake

The investigation of the vertical distribution of the zooplankton community in the temperate Lake Trichonis during four seasons in 2005, showed the existence of vertical segregation among species, ontogenetic stages and sexes within and between the major groups. In each season, the two or three more abundant rotifer species distributed at separate depth layers, while this feature was maintained during the entire 24 h period, since no diel vertical migrations (DVM) were performed. In contrast, the crustacean community, comprised mainly by the calanoid copepod Eudiaptomus drieschi and the cladoceran Diaphanosoma orghidani, showed various patterns of DVM, being more pronounced in spring and summer. Females of E. drieschi distributed deeper than males, while the copepod nauplii were found mainly in the surface layer in all four seasons. Temperature was the most important abiotic factor affecting directly and indirectly the vertical distribution and migration of various species. During stratification, the metalimnion was the most productive layer in Lake Trichonis, having maximum values of dissolved oxygen and low transparency due to high concentration of organic matter and phytoplankton. The DVM patterns of the crustaceans indicate that the metalimnion acts probably as a daylight refuge against predation by Atherina boyeri, which is the dominant planktivorous fish in the lake.     

澜沧江西双版纳段鱼类组成和物种多样性

根据2018-2020年澜沧江西双版纳段5次鱼类资源调查数据,结合相关文献资料,对该流域鱼类组成及物种多样性进行了分析。结果显示：澜沧江西双版纳段此次共调查到鱼类119种,隶属于11目28科79属,而历史记录鱼类共179种,隶属于12目34科106属。随着调查的不断深入,土著鱼类种数逐渐增多,但占比却逐渐下降,外来鱼类种数逐渐增多,占比也逐渐升高;本次调查到土著鱼类92种,占鱼类种数的77.31%,占比进一步下降;外来鱼类27种,占鱼类种数的22.69%,占比进一步升高。该区域鱼类优势种为云南吻孔鲃Poropuntius huangchuchieni和少鳞舟齿鱼Scaphiodonichthys acanthopterus,常见种为长臀鲃Mystacoleucus marginatus和宽额鳢Channa gachua。有《国家重点保护野生动物名录》（2021年）鱼类5种,《中国生物多样性红色名录脊椎动物卷》（2015年）受威胁鱼类8种。相对于我国其他江河,澜沧江西双版纳段有极高水平的鱼类物种多样性,其中澜沧江干流鱼类物种多样性相对于左、右岸支流较低,左岸支流鱼类多样性高于右岸,罗梭江鱼类多样性高于其他一级支流。虽然澜沧江西双版纳段鱼类物种多样性维持在较高水平,但土著鱼类占比下降趋势明显,仍面临着严重威胁,本文分析了受威胁因素,并提出了保护建议。     

Ichthyofaunal survey of rivers within Ewekoro cement manufacturing operational areas

A total of 298 fish specimens belonging to seven families were caught during ichthyoplanktonic survey of three rivers within the Ewekoro cement facility catchment area located in southwestern Nigeria. The highest numbers of specimens were caught from Alaguntan (37.0%) and Elebute (36.6%) rivers while 28.9% of the fish samples were collected from Itori River. The fish population and species diversity recorded in the catchment rivers were significantly lower (p < 0.05) than comparative catches from Ewekoro River located about 30 km downstream of the factory operational area. The food items ingested by the specimens across the seasons in the catchment rivers revealed obvious differences in diet with some degree of overlap in the fish trophic preferences. However, the omnivorous species dominated the catches in each of the rivers, irrespective of season. Categorization of the fish specimens based on habitat-related adaptive physiology showed that a significant number of the fish from Alaguntan and Itori Rivers have accessory respiratory organs. The four species with accessory respiratory organs were Polypterus senegalus Curv., Clarias gariepinus C. & V., Ctenopoma kingslayae Gun. and Channa obscura Smith. Of the 12 fish species recorded in the Ewekoro cement facility catchment rivers, only P. senegalus, C. gariepinus, C. obscura and Oreochromis niloticus (Trew.) are valuable food fishes in southwestern Nigeria.     

Size related variability in the summer diet of the blackfin tuna (Thunnus atlanticus Lesson, 1831) from Tobago,the Lesser Antilles

Blackfin tuna (Thunnus atlanticus) is a small epipelagic oceanic species known only from the western Atlantic. In Tobago, the Lesser Antilles, blackfin tuna is caught by the artisanal fishery. The diet of this species was examined during the summer of 2004 for fish landed at the Charlotteville fish market in Tobago. T. atlanticus ranged from 32 to 91 cm FL (0.7–12.4 kg). Overall numerical abundance of prey items comprised fish (48%), crustaceans (46%) and cephalopods (6%). Prey species included small pelagics such as anchovies (ranked as most important prey overall), juveniles of larger pelagics such as jacks, juveniles of fish found in coral reef communities as adults, e.g. squirrelfishes, and some mesopelagic species. The importance of major diet categories differed significantly with predator size, with fishes becoming more important and crustaceans less important with increasing size of the blackfin tuna. This study has improved our scant knowledge of the blackfin tuna diet in the Lesser Antilles.     

江西柘林水库鱼类群落结构及功能多样性分析

为了解江西柘林水库鱼类群落结构和多样性的时空变化特征,研究鱼类物种多样性和功能多样性的关系,于2020年9月至2021年4月在该水库调查分析了鱼类物种组成、优势度及群落物种多样性和功能多样性。结果表明,共采集鱼类53种,分属于5目12科36属。其中,鲤形目(38种)种类最多,占调查物种数的71.69%,柘林水库上、中、下游库区分别采集到鱼类36、40和32种,各库区均以鲤形目鱼类为主,分别占采集物种数的72.97%、85.00%和75.00%。优势物种主要是■(Hemiculter leucisculus)、鳙(Aristichthys nobilis)和黄尾鲴(Xenocypris davidi),重要种主要是草鱼(Ctenopharyngodon idella)、鲢(Hypophthalmichthys molitrix)、鳊(Parabramis pekinensis)、鲫(Carassius auratus)、蒙古红鲌(Erythroculter mongolicus)等。鱼类群落结构季节性差异大于空间格局差异,主要表现为秋季和冬季之间;生物多样性指数Margalef和功能丰富...     

Distribution and diet of the roughskin sculpin, <Emphasis Type="Italic">Trachidermus fasciatus</Emphasis>, larvae and juveniles in the Chikugo River estuary,Ariake Bay,Japan

Larvae and juveniles of the roughskin sculpin Trachidermus fasciatus were collected during four cruises in March and April 2001 to study the distribution and diet of the fish in the Chikugo estuary in the northern Ariake Bay, Japan. Sampling was conducted at seven stations covering an area approximately 30 km in length along the estuary, with salinity ranging from nearly 0 to about 30 PSU. Gut contents were analyzed by separating, identifying, and counting the prey organisms. Plankton samples were collected during each cruise to study the numerical composition and abundance of copepods in ambient water. A total of 1790 larvae and juveniles of T. fasciatus were collected; they were distributed in the five uppermost stations, covering approximately 20 km and ranging in salinity from 0.4 to 27.4 PSU. The fish fed almost exclusively on a single calanoid copepod species, Sinocalanus sinensis, which was numerically the most abundant in the ambient water at the upper part of the Chikugo River. At the lower part of the river, the fish positively selected S. sinensis while negatively selecting other species. T. fasciatus larvae experienced a high proportion of empty guts and low feeding intensity at around 9.0 mm body length, which appears to be associated with commencement of exogenous feeding. The proportion of empty guts reduced sharply at subsequent stages and was accompanied by an increase in feeding intensity. The oligohaline and mesohaline areas are important nursery grounds, and S. sinensis is an important prey copepod species for the larval and juvenile T. fasciatus in the Chikugo estuary.     

Fishery, seasonal abundance and mortality of grey mullets (Pisces: Mugilidae) in Negombo Lagoon, Sri Lanka

The seasonal abundance and instantaneous natural and fishing mortalities of six species of grey mullets, namely Liza subviridis, L. macrolepis, L. tade, Mugil cephalus, Valamugil buchanani and V. cunnesius were studied as a prelude for the management of their fishery in Negombo lagoon (7°10′N and 79°50′E). L. subviridis was the most abundant of the grey mullet species in the commercial catches and accounted for 37% of the total grey mullet catch. M. cephalus was the least abundant and constituted 6%. The annual catch of grey mullets was estimated to be around 23 000 kg (5.67 kg/ha); about 40 % of the total fish landings of the lagoon. The seasonal variation in the catch of different species of grey mullets appear to be related to their breeding seasons and spawning migrations. The highest value for instantaneous natural and fishing mortalities, which were 1.04 and 0.94 respectively were obtained for V. cunnesius. The lowest values for instantaneous natural and fishing mortalities which were 0.51 and 0.19 respectively were obtained for M. cephalus. The exploitation ratios calculated were less than 0.5 for all species other than L. tade which suggest that the grey mullet populations excluding L. tade in this lagoon may presently be underexploited.     

Diversity and composition of estuarine and lagoonal fish assemblages of Socotra Island,Yemen

Estuarine and lagoonal surveys of Socotra Island and selected sites on the Hadhramout coast of Yemen were conducted with the objective of documenting and analysing fish diversity and assemblage structure. A total of 74 species in 35 families were recorded, among which 65 species in 32 families were from Socotra and 20 species in 17 families were from mainland Yemen. Twenty‐one species represent new faunal records for Socotra. Including historic records re‐examined in this study, the total fish species richness of estuaries and lagoons of Socotra Island reaches 76, which is relatively high compared to species inventories of well‐researched coastal estuaries in southern Africa. Five species dominate the occurrence and abundance frequencies: Terapon jarbua, Hyporhamphus sindensis, Aphanius dispar, Ambassis gymnocephala and Chelon macrolepis. Rarefaction and extrapolation analyses suggest that the actual number of fish species inhabiting some of those estuaries might be higher than the one observed. Thus, additional sampling at specific sites should be conducted to record other less conspicuous species. Ordination and multivariate analyses identified four main distinct assemblage clusters. Two groups are geographically well structured and represent northern Socotra and mainland Yemen, respectively. The other two assemblage groups tend to be determined to a greater extent by the synchrony between physical (e.g. estuary opening periods) and biological (e.g. spawning and recruitment periods) variables than by geographical location. Finally, the single intertidal lagoon of Socotra represents by itself a specific fish assemblage. The high proportion of economically important fish species (38) recorded underscores the paramount importance of these coastal water bodies as nursery sites, and for sustaining vital provisioning ecosystem services.     

Phylogenetic relationships of Amazonetta,Speculanas, Lophonetta,and Tachyeres: four morphologically divergent duck genera endemic to South America

We studied the phylogenetic relationships of four duck genera endemic to South America: Brazilian teal Amazonetta brasiliensis, spectacled duck Speculanas specularis, crested duck Lophonetta specularioides, and four species of steamer ducks Tachyerespatachonicus, T. leucocephalus, T. pteneres, T. brachypterus. Genetic divergence within and among species was compared using population‐level sampling of the mitochondrial DNA (mtDNA) control region, supplemented with three additional mtDNA genes and six independent nuclear loci from one individual of each species and a variety of outgroup taxa. The monophyly of these four morphologically divergent South American genera was strongly supported. Within this clade, Amazonetta and Speculanas were supported as sister species in all analyses, but different gene regions yielded conflicting or ambiguous results for Lophonetta and Tachyeres. This lack of resolution resulted from little informative variation in nuclear loci and high levels of homoplasy in the mtDNA control region. Control region sequences from the four Tachyeres species fell into two distinct clades. In one clade, T. patachonicus and T. leucocephalus share a set of closely related haplotypes (≤0.6% sequence divergence); while no identical haplotypes were shared between species, the control region phylogeny was insufficiently resolved to either support or reject reciprocal monophyly. The second clade, ~1.7% divergent from the first, comprised haplotypes of the Falkland Islands species T. brachypterus and a captive individual of T. pteneres. These distinctive South American ducks likely experienced two bouts of rapid diversification, thus making analysis of their phylogenetic relationships difficult. Incomplete lineage sorting, founder effects, and perhaps introgression likely have contributed to obscuring the relationships among steamer ducks.     

Trophic interrelationships amongst cichlid fishes in a tropical African reservoir (Lake Chivero,Zimbabwe)

The diet of seven cichlid species of Lake Chivero, Zimbabwe, was investigated from October 2004 to April 2005 to determine the degree of dietary overlap and interspecific competition. These fish could be separated into four groups. Two microphages, Oreochromis niloticus and O. macrochir, fed mostly on blue-green algae and their diets, in all size classes, overlapped almost completely. This suggested a high degree of competition between the two species and may account for the fact that O. niloticus, introduced into the lake in the 1980s is now the dominant species. There was also a significant dietary overlap between the two macrophages Tilapia sparrmanii and T. rendalli, which were macrophages with macrophytes as a significant component of their diet. Interspecific competition between these two species may account for the increase in the abundance of T. sparrmanii and a decrease in the numbers of T. rendalli over the last two decades. The diet of two small omnivores Pharyngochromis acuticeps and Pseudocrenilabrus philander consisted of algae, zooplankton, plant material, fish and detritus and also overlapped extensively, but these species probably avoid competition by living in different habitats; P. philander is usually associated with vegetation while P. acuticeps tends to live in more open waters. The last species, Serranochromis robustus, was largely piscivorous. There were no ontogenetic variations in diet, apart from P. acuticeps where small fish fed mainly on zooplankton becoming omnivorous in larger ones, and S. robustus where the diet shifted from zooplankton in specimens <50 mm SL to fish in larger size classes. Data available from the 1960s and 1970s indicate that the diets of some species have changed with invertebrates such as chironomid larvae being previously more important in all diets, while most species now take a higher proportion of algae. This reflects changes in the lake, which is eutrophic and has experienced severe algal blooms since 1960. Handling editor: C. Strumbauer     

Diet comparison among demersal marine fish from the Canadian Arctic

Summary The diets of 12 species of demersal marine fish from various locations in the Canadian Arctic comprised a grand total of 267 prey species, mainly invertebrates. The total number of prey species taken by a single fish species ranged from 9 to 91, and the mean number per stomach from 2.0 to 9.4. The most important prey were Crustacea, most frequently epibenthic or planktonic species; Polychaeta, mainly the larger species; and Mollusca, notably the cropped siphons of Macoma calcarea. Generally, only a few species comprised the bulk of the food. Most of the fish had a predominantly benthic or epibenthic diet, a notable exception being Triglops pingeli which ate zoo plankton almost exclusively at the three sites from which it was collected. To a lesser extent, Triglops murrayi, Icelus spatula and Liparis gibbus also fed planktonically. No significant correlations in diet were found among sympatric fish populations, implying a division of resources and reduced interspecific competition.     

Ecological fish production in Long Pond,a lakeshore lagoon on Long Point,Lake Erie

Synopsis Long Pond, a recently formed 2.4 ha lagoon on Long Point, Lake Erie (Canada), was treated with piscicide and found to contain 47,768 fishes of 22 species. Nine dominant species (Notropis heterolepis, Pimephales notatus, Notemigonus crysoleucas, Lepomis gibbosus, L. macrochirus, Perca flavescens, Cyprinus carpio, Micropeterus salmoides and Carassius auratus) comprised 91% and 97% of total numbers and standing crop respectively. Age, growth and production were determined giving a total fish production estimate (corrected for all species) of 87.5 kg ha^–1 y^–1 for this lagoon. Dominant species were deemed either invaders (Cyprinus carpio, Carassius auratus), which had entered the lagoon to spawn and been trapped, or residents. The invaders comprised 82% of the 277.8 kg ha^–1 total standing crop. Their successful spawning and subsequent escape of the young from the lagoon would have resulted in some 615 kg y^–1 of fish production outside the lagoon. Resident stocks were dominated by young fishes, a characteristic of exploitation or early colonization. This may have been due to the recent formation and subsequent expansion of the lagoon or high annual mortality due to extreme physical conditions but was most likely the result of excessive predation by Micropterus salmoides. Relationship between biomass and production show that the chance inclusion of the invaders produces an immediate shift from a characteristically early to a characteristically late phase of ecological development.     

Comparison of fish assemblages among an artificial reef, a natural reef and a sandy-mud bottom site on the shelf off Iwate, northern Japan

Synopsis Fish assemblages at an artificial reef site, a natural reef site and a sandy-mud bottom site, on the shelf (depth 130 m) off Iwate Prefecture, northern Japan, were surveyed by using a bottom trammel net from May 1987 to March 1993. A total of 12 173 fishes of 48 species were recorded. Physiculus maximowiczi was dominant and comprised 69% of the total numerical abundance. Total fish number was lowest in March at all the 3 sites when P. maximowiczi migrated to deeper and warmer waters. Assemblage equitability and species diversity also varied seasonally in accordance with the abundance fluctuation of P. maximowiczi. P. maximowiczi, Alcichthys alcicornis and Hexagrammos otakii were more abundant at the artificial reef and natural reef sites, while Dexistes rikuzenius and Hemitripterus villosus were more abundant at the sandy-mud bottom site; total fish abundance was largest at the artificial reef site mainly due to the large number of P. maximowiczi. Species richness was similar among sites, but equitability, and consequently species diversity, was lowest at the artificial reef site. The main effect of the artificial reef seemed the attraction of P. maximowiczi from nearby bottoms, especially from natural rocky reefs; its large abundance determined the structure of the artificial reef fish community.     

东太湖鱼类群落结构特征及其与环境因子的关系

基于2019年4月、7月和10月的调查数据,用多元分析方法研究了围网拆除后东太湖鱼类群落结构的变化,及其与主要环境因子的关系。共调查到鱼类4目10科31属39种,其中鲤形目鱼类占69.23%。按不同生态类型东太湖鱼类主要为定居性鱼类、中上层鱼类以及肉食性和杂食性鱼类。优势种为鲫（Carassius auratus）、大鳍鱊（Acheilognathus macropterus）和（Hemiculter leucisculus）等。鱼类的种类数、渔获量、丰富度指数和多样性指数在监测月份间均差异显著（P＜0.05）,均为4月 > 7月 > 10月。鱼类个体呈现小型化,鱼类物种多样性处在一般水平。等级聚类分析（Cluster）结果表明,除10月份的1号点和3号点外,各样方间的相似度在46.75%以上。单因子相似性分析（ANOSIM）和相似性百分比分析（SIMPER）也表明,4月和10月的鱼类群落物种组成差异显著,平均相异性为59.41%。丰度/生物量曲线（ABC）分析表明,东太湖鱼类群落结构处于中度干扰状态。冗余分析（RDA）表明,总磷对主要鱼类变化的解释量为21.0%,是重要的解释因子（蒙特卡罗检验P＝0.036）。而总磷、pH、溶解氧等是目前影响东太湖鱼类群落的主要环境因子。     

黄山陈村水库上游河源溪流的鱼类群落及其纵向梯度格局

确定鱼类群落的分布格局及其对人类活动的响应,是合理保护、恢复和管理鱼类多样性的基础。基于2011年5月和10月自黄山陈村水库上游3条河源溪流共39个样点的调查数据,比较研究了溪流间鱼类群落及其纵向梯度格局的异同,着重探讨了人类活动对溪流鱼类群落纵向梯度格局的影响。研究结果显示,同人为干扰较轻的舒溪相比,人为干扰严重的浦溪和麻溪中水宽、底质和植被覆盖率等局域栖息地条件显著变化,这造成了后者的鱼类多样性显著下降及物种组成的显著变化,主要表现为敏感性的地方物种(如宽鳍鱲、光唇鱼、原缨口鳅等)数量减少、耐受性的广布物种(如泥鳅、麦穗鱼、高体鰟鲏等)数量增多。舒溪的鱼类物种数及其组成均与海拔显著相关,但这种"海拔-鱼类群落"关系在麻溪和浦溪中削弱甚至消失。底质、植被覆盖率对舒溪鱼类群落具有重要影响,但对浦溪和麻溪鱼类群落却无显著影响。研究结果表明,在子流域空间尺度上,诸如城镇化发展、土地利用、河道治理等人类活动可通过对局域栖息地条件的影响,导致溪流鱼类多样性下降及其物种组成的变化,破坏鱼类群落的纵向梯度格局,并改变栖息地与鱼类群落之间的联系。