Land/water ecotone effects in reservoirs on the fish fauna

The morphology and function of one tropical and 25 temperate reservoirs are examined in relation to their effect upon the nature of the land/water interface and, further, to what extent the features of these ecotones satisfy the ecological requirements of the reservoir fish species throughout their life cycle during spawning, larval, juvenile and adult stages. The two main conclusions are that (1) reservoir fish species are especially dependent upon land/water ecotones during their early life history and (2) there exists a strong relationship between the extent of the littoral area and the nature of the fish stocks. Several examples are given to show that manipulation of the land/water ecotone is a major tool for the management of reservoirs advantageously for their major functions.     

Spatio-temporal patterns of fish assemblages in a large regulated alluvial river

1. The River Durance, the last alpine tributary of the River Rhône, is a large, braided alluvial hydrosystem. Following large-scale regulation, flow downstream of the Serre-Ponçon dam has been maintained at 1/40th of previous annual mean discharge. To assess the effects of historical disturbances, fish assemblages and habitat use were analysed during five summers in a representative reach of the middle Durance.
2. Habitat availability and use were assessed with a multi-scale approach including the variables water depth, current velocity, roughness height of substratum, amount of woody debris and lateral/longitudinal location. Eighteen fish species were sampled by electrofishing in 289 habitat sample units.
3. Partial least square (PLS) regression showed that taxa were mainly distributed according to relationships between their total length and water depth/velocity variables. Fish assemblage composition was also related to roughness height as well as distance from the bank or to the nearest large woody debris. However, PLS regression revealed no significant differences in habitat selection between two periods of varying hydromorphological stability.
4. Fish distribution patterns and density were related to proximity to the bank and cover, indicating that local scale variables need to be considered in conservation and restoration programmes.     

台湾海峡鱼类组成及其生态区系

本文依据台湾海峡鱼类物种的相关历史调查资料和文献, 分析了台湾海峡鱼类物种组成及其生态类型和区系特征, 探讨全球变化背景下台湾海峡鱼类物种组成变化。结果显示, 台湾海峡共有鱼类1,697种, 分隶40目206科740属, 其中, 目级分类阶元种类数最多的为鲈形目, 科级分类阶元种类数最多的为鰕虎科; 从适温性上看, 暖水性鱼类最多, 有1,560种, 其次为暖温性鱼类(128种)和冷温性鱼类(9种); 栖息地生态类型则以大陆架砂泥质底层鱼类和岩礁性鱼类种类数最多, 各有596种, 其后依次是大陆架近底层鱼类(249种)、大陆架中上层鱼类(158种)和大洋性鱼类(98种), 洄游性鱼类181种, 经济性鱼类735种; 海区间鱼类种类数对比显示, 台湾海峡鱼类与南海鱼类共有种最多, 共有种比例高达91.9%, 其次为东海(69.3%)和黄海(19.4%), 多为印度—西太平洋海区分布种, 仅288种广泛分布于中国各海区。由此, 台湾海峡鱼类区系特征兼有热带和亚热带海区鱼类区系特点, 属于印度—西太平洋暖水区系中—日亚区和印度—马来亚区的过渡海区, 其分界区域在台湾浅滩东部外缘至澎湖列岛偏北海域。     

Relating life‐history traits,environmental constraints and local extinctions in river fish

相似文献   

Prioritising the rehabilitation of fish passage in a regulated river system based on fish movement

Environmental rehabilitation budgets are often limited, and management actions need to be prioritised to achieve the best outcomes. Prioritisation can best be done when evidence informs the decision‐making process. We acoustically tagged twenty Golden Perch (Macquaria ambigua) in the Loddon River, Australia, and tracked their movements to gain an understanding on the requirements for fish passage at a major regulating structure, the Box Creek regulator. The movements of these fish were monitored through a network of receivers located throughout the lower Loddon River and Pyramid Creek system. Five fish moved 50–120 km upstream, four of which reached the Box Creek regulator before moving back downstream to the entrance of the Kerang Lakes system. Most long distance upstream movements were associated with an increase in river discharge. The remaining 15 fish moved <20 km, with all fish being detected at least once. This pilot study indicates that Box Creek regulator is acting as a barrier for some fish within the Loddon River system. Movement data also indicate that Golden Perch migration pathways may be influenced by river discharge. The management implications of this work includes the need to reinstate fish passage at Box Creek regulator and the potential use of environmental flows to enhance colonisation of native fish species throughout the Murray Darling Basin.     

川西高山林线交错带土壤动物对岷江冷杉和高山杜鹃凋落物分解的贡献

土壤动物是调控凋落物分解的重要生物因素.为了探究川西高山林线交错带土壤动物对两个优势物种岷江冷杉和高山杜鹃凋落物分解的贡献,在3个海拔梯度(针叶林-林线-高山草甸)采用凋落物分解袋试验,通过不同孔径的网袋(0.04 mm,基本排除土壤动物;3 mm,允许土壤动物通过),研究了分解554 d(2013年5月—2014年11月)土壤动物对凋落物的影响.结果表明: 在整个林线交错带上,岷江冷杉的分解速率(k)为0.209～0.243,高山杜鹃的k为0.173～0.189,岷江冷杉的k大于高山杜鹃.土壤动物的参与显著加速了两种凋落叶分解,同时土壤动物对两种凋落物分解的作用和贡献随海拔升高而降低.自针叶林、高山林线至高山草甸,土壤动物对岷江冷杉分解的质量损失率为15.2%、13.2%、9.8%,对高山杜鹃分解的质量损失率为20.1%、17.5%、12.4%;土壤动物对岷江冷杉分解的平均日贡献率为0.17%、0.13%、0.12%,对高山杜鹃分解的平均日贡献率为0.26%、0.25%、0.23%,土壤动物对高山杜鹃的分解影响相对较大.海拔、凋落物自身性质及其交互作用对土壤动物作用下凋落物的质量损失率和贡献率均表现出显著影响.土壤动物的作用于岷江冷杉和高山杜鹃分解的平均日贡献率在当年生长季(0.25%和0.44%)和次年生长季(0.10%和0.19%)均高于雪被期(0.07%和0.12%).回归分析表明,环境因子(日平均气温、冻融循环次数以及雪被厚度)可以解释土壤动物作用于岷江冷杉和高山杜鹃质量损失率的42.7%和50.9%,贡献率的43.2%和55.6%,这对了解土壤动物在凋落物分解中的作用和深入认识高山生态系统物质循环具有重要意义.     

Applying an index of biotic integrity based on fish assemblages in a West African river

A multivariate measure of river quality, the Index of Biotic Integrity (IBI), was adapted to a West African river, the Konkoure (Republic of Guinea). Fish assemblages were sampled using gill-nets during the dry season to provide data for the IBI. Ten metrics were subsequently defined. The capacity of the modified IBI to assess the impact of a bauxite treatment plant was tested. The IBI decreased as expected at the impacted station. Detailed examination of the data revealed that one family, the Mormyridae, was almost eliminated from the impacted station, suggesting that members of this familiy can be considered as intolerant species in future uses of the IBI in other African rivers.     

River channelization effects on fish population structure in the Larraun river (Northern Spain)

As a consequence of the construction of the A-15 highway between 1991 and 1995, some modifications affecting the Larraun River (Navarra, North of Spain) were made. One of the most important effects was the channelization of a section of the river in the middle zone. Fish were caught by electrofishing in August of 1996 in the channelized reach, as well as in non-modified stretches upstream and downstream. Physical and chemical variables and shelter availability were also analyzed. The captured fish were measured (total length) and released into the river. We calculated the density, biomass, length distribution and diversity, comparing the obtained results from the different stretches. The number of species was higher in the lower zones of the river and diversity increased progressively downstream. The fish density in the channelized section was slightly lower than in the other two points. Also biomass in the channelized section was about a factor of 10 smaller than the calculated biomass in unaltered points. Moreover, in comparison with the unaltered sections of the river, in the channelized area a major decrease in the presence of fish larger than 150 mm was detected. The low shelter availability in the channelized section, lack of bank vegetation and alterations in the substratum could explain the observed variations in the length distribution, biomass and the lower value of the density of European minnow, Phoxinus phoxinus (Linnaeus, 1758).     

Large-scale assessments of river health using an Index of Biotic Integrity with low-diversity fish communities

1. Effective tools are needed to measure the ‘health’ of rivers at scales large enough to be useful for management. Indicators for assessing the complex of variables that constitutes river health need to be ecologically based, efficient, rapid and consistently applicable in different ecological regions. 2. A large-scale survey of rivers in New South Wales, Australia provided data to test the Index of Biotic Integrity (IBI). The IBI employs the fish-community attributes, identified using regional and river-size data, expected for a river reach of excellent environmental quality. It uses metrics based on species richness, abundance, community structure and the health of individual fish. IBI metrics were established to suit a relatively low-diversity and unspecialized freshwater fish fauna in south-eastern Australia, totalling 55 species. 3. The IBI was able to discriminate between relative levels of environmental quality within a diverse set of stream systems and four presumptive ecological regions. The index was validated by testing the repeatability of scores, and by comparison of IBI scores at eighty sites with an independent measure of potential catchment condition, the River Disturbance Index. 4. Assessments of metric performance showed that eleven of the twelve metrics contributed satisfactorily. One metric based on trophic guild performed poorly and should be deleted from the index. Six other recommendations are made to enhance the performance of the IBI. 5. Results show that, while all large rivers have been disturbed, rivers in the Murray region and those in many coastal montane areas are particularly degraded. 6. The IBI results presented here demonstrate a validated method for large-scale monitoring of river health based on a fish fauna of limited diversity, in the absence of suitable reference sites.     

漓江水陆交错带截污效果评价

水陆交错带作为水生、陆地生态系统之间的过渡带,具有拦截水体污染物、保护河流水质等重要作用。根据立地划分原则并结合广西壮族自治区漓江风景区实际情况,将漓江水陆交错带划分为6种立地类型:薄土层河滩地、中土层河滩地、厚土层河滩地、薄土层岸坡地、中土层岸坡地、厚土层岸坡地,筛选了14个指标并建立指标评价体系,利用层次分析法将漓江水陆交错带截污效果分为4个等级:优、良、中、差。评价结果如下:在漓江水陆交错带选取了20块样地,其中,薄土层河滩地占5%、中土层河滩地占10%、厚土层河滩地占10%、薄土层岸坡地占10%、中土层岸坡地占35%、厚土层岸坡地占30%,评价为"优"、"良"、"中"、"差"的样地分别占10%、60%、25%、5%,说明漓江水陆交错带整体截污效果良好,但是有少部分区域急需修复,部分区域有潜在生态危险。根据评价结果,针对不同截污效果的漓江水陆交错带,提出最佳的生态修复措施,对漓江水陆交错带生态修复工作具有指导意义。     

Synergistic and antagonistic interactions of future land use and climate change on river fish assemblages

River ecosystems are threatened by future changes in land use and climatic conditions. However, little is known of the influence of interactions of these two dominant global drivers of change on ecosystems. Does the interaction amplify (synergistic interaction) or buffer (antagonistic interaction) the impacts and does their interaction effect differ in magnitude, direction and spatial extent compared to single independent pressures. In this study, we model the impact of single and interacting effects of land use and climate change on the spatial distribution of 33 fish species in the Elbe River. The varying effects were modeled using step‐wise boosted regression trees based on 250 m raster grid cells. Species‐specific models were built for both ‘moderate’ and ‘extreme’ future land use and climate change scenarios to assess synergistic, additive and antagonistic interaction effects on species losses, species gains and diversity indices and to quantify their spatial distribution within the Elbe River network. Our results revealed species richness is predicted to increase by 0.7–2.9 species by 2050 across the entire river network. Changes in species richness are likely to be spatially variable with significant changes predicted for 56–85% of the river network. Antagonistic interactions would dominate species losses and gains in up to 75% of the river network. In contrast, synergistic and additive effects would occur in only 20% and 16% of the river network, respectively. The magnitude of the interaction was negatively correlated with the magnitudes of the single independent effects of land use and climate change. Evidence is provided to show that future land use and climate change effects are highly interactive resulting in species range shifts that would be spatially variable in size and characteristic. These findings emphasize the importance of adaptive river management and the design of spatially connected conservation areas to compensate for these high species turnovers and range shifts.     

The contribution of long‐term isolated water bodies to floodplain fish diversity

1. Floodplains and their water bodies are typical ecotopes of large lowland rivers. The lowland Oder River, Germany, provided a rare opportunity to study fish assemblages of comparable floodplain water bodies differing by >50 years of isolation history. We hypothesised that true floodplain specialists peak in rarely connected water bodies, while frequently flooded waters support tolerant generalists. 2. Three macrohabitats, main channel (MC), temporarily connected and isolated floodplain water bodies, were sampled by electro‐fishing and their fish assemblage characters recorded. 3. Long‐term isolation of floodplain water bodies had a significant effect on the fish assemblage by promoting species preferring still water. Limnophilic and floodplain specialist species significantly increased with isolation. 4. Fish densities, species richness and diversity clearly differed between MC sites and floodplain water bodies. Shannon’s species diversity index peaked in both the MC and isolated waters and was lowest in the temporarily flooded waters where eurytopic fish dominated. 5. The significant gain in abundance and numbers of limnophilic species in the isolated compared to the temporarily flooded water bodies underpinned the significant contribution of long‐term isolated waters to the gamma‐diversity of large floodplain rivers, which should be considered in floodplain rehabilitation.     

Recent increase of filamentous algae in shallow Swedish bays: Effects on the community structure of epibenthic fauna and fish

A summary is presented of estimates of distribution and growth of filamentous algae and its effect on the structure and functioning of epibenthic fauna and fish communities in shallow bays on the Swedish west coast. As a consequence of coastal eutrophication vegetation cover has gradually increased during the last decade, and during 1990's most bays in the Skagerrak-Kattegat area were variously covered with filamentous algae during spring and summer (May–July). In some areas filamentous algae (mainlyCladophora andEnteromorpha) completely covered the bottom. In field studies it was demonstrated that increased cover and dominance of filamentous algae result in structural changes of the epibenthic fauna community. Field studies showed that species richness and biomass of epibenthic fauna increased in a sandy bay with a moderate increase (30 to 50%) of filamentous algae cover. At higher cover (90%), biomass of epibenthic fauna was reduced, however, to the same level as for the sandy habitat, although the dominant epibenthic species were different. Heavy growth of epiphytic filamentous algae on eelgrass resulted in reduced biomass and a shift in the species composition of the epibenthic fauna community. Fish assemblage structure was also related to changes in vegetation. In eelgrass beds, fish species numbers were reduced with increasing cover of epiphytic filamentous algae, and at rocky bottoms with kelp algae (dominated byFucus), fish biomass decreased with increasing cover of attached filamentous algae. Further, foraging efficiency of juvenile cod and settling success of plaice were reduced as a response to increasing dominance of filamentous algae.     

坡度对农田土壤动物群落结构及多样性的影响

为了研究坡度对土壤动物群落的影响,于2010年3月和9月分别对川中丘陵区坡度为5°、15°、25°的3种农田土壤动物进行了调查。共采集土壤动物11657只,隶属4门11纲21目,弹尾目、蜱螨目、颤蚓目和线虫为优势类群。土壤动物群落的类群数在3月随坡度增加无显著变化(P>0.05),9月则呈波动性上升(P<0.01)。群落密度在3月随坡度增加而显著下降(P<0.01),9月的变化趋势则相反(P<0.05)。群落多样性指数在3、9两月均随坡度增加呈显著波动性变化(P<0.05)。坡度对弹尾目、蜱螨目和线虫等主要类群的密度影响显著(P<0.05),并具季节差异。主成分分析(PCA)结果表明坡度对农田土壤动物的群落结构有明显影响,Sorenson和Morisita-Horn相似性系数进一步表明坡度在3月份主要影响土壤动物群落的类群组成,在9月主要影响优势类群的密度。研究结果表明坡度对土壤动物的群落结构、多样性及主要类群的密度有显著影响,并存在季节差异。     

Heavy metals in water,sediments, fish and plants of river Hindon,U.P., India

We analysed the concentrations of Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn in the water, sediments, fish and plants of the River Hindon, U.P., India, at seven sampling stations, in the year 1982. Considerable variation in concentration between water, sediments, fish and plants were noted. The concentration in the water was in the order Fe > Zn > Cr > Mn > Cu > Pb > Ni > Co > Cd, in the sediments, Fe > Mn > Zn > Ni > Cr > - Co > Cu > Pb > Cd; in a fish (Heteropnuestes fossilis) Fe > Zn > Mn > Pb > Ni > Co > Cu > Cd > Cr, and in a plant (Eicchornia crassipes) Fe > Mn > Zn > Ni > Cu > Cr > Pb > Co > Cd.     

Sensory structures at the surface of fish skin I. Putative chemoreceptors

Fish skin contains solitary epidermal sensory cells which, on evidence from their cytology, are believed to be chemosensory. The external appearance of the apical sensory processes of these cells, as seen by scanning electron microscopy, is shown in four species of ostariophysan teleosts, and is compared with the morphology of the pores of external taste buds. The apical processes of the gustatory cells are simple in form in all cases so far investigated in gnathostome fishes, but in some cases the solitary sensory cells have apical processes divided distally into a number of smaller processes. In the dipnoan fish Protopterus amphibius , external taste buds have simple blunt gustatory processes protruding through a cap of mucus that covers the taste bud pore. Solitary sensory cells in this species have a bulbous undivided apical process. In the lampreys, the 'end buds' have an apical morphology different from the taste bud pores of teleost fish. Lamprey epidermis has numerous solitary sensory cells each bearing a number of microvilli.     

The effects of suspensoids on fish

High suspensoid loads are a common feature of many Southern Hemisphere inland waters. Case studies on a natural lake (Chilwa), a man-made lake (Le Roux) and S.W. Indian Ocean estuaries reveal that the effects of turbidity on fish in these systems differ widely. In Lake Le Roux, high suspensoid loads influence fish by causing a reduced growth rate, a decrease in size at first maturity and maximum size, and a movement inshore by large fishes to feed on phytobenthos. High turbidities in Lake Chilwa sharply reduce food availability in benthic offshore zones, and restrict fishes to pelagic and inshore food resources. The resuspension of sediments by wind action may cause fish mortalities through deoxygenation of the water column. Moderate turbidity levels appear to be beneficial to fish in estuaries by affording protection from predators in shallow, food-rich areas. Turbidity gradients may also provide a navigational aid to fish entering estuaries.While ecological studies on Southern Hemisphere inland waters are fairly advanced, experimental work is restricted. Such research in the Northern Hemisphere has revealed that high suspensoid loads may influence breeding success, egg and larval survival, population structure and size, as well as food availability and feeding efficiency. The effect of suspensoids on the breeding success and feeding efficiency of Southern Hemisphere fish needs further investigation.Moderate suspensoid loads are a natural feature of many inland waters, but sustained high levels reduce the photic zone, blanket the benthos and interfere with the feeding efficiency of fish. The curtailment of soil erosion should therefore be regarded as a priority in the management of inland fisheries, especially in Third World countries where poor land-use practises have resulted in a marked deterioration of water quality. The need to study and manage river catchments holistically is emphasized.