Spring Habitats Research Articles

Habitats with Large Bitter Cress (Cardamine amara L.) in the Spring Area of Nera River (Semenic Mountains, Romania)

Abstract The paper presents the spring habitats and their communities edified by the Large Bitter Cress (Cardamine amara L.) in the area of Nergăniţa, a headwater stream of the Nera River included in the “Nature Reserve Semenic Mountains and springs of Nera River”. The communities of Large Bitter Cress are situated in and on the springs and spring streamlets situated in the beech forest area, being well adapted to the special site conditions with low water temperatures, low light conditions and humus rich soils. The species composition of the Large Bitter Cress communities and their habitats are presented in strong relation with the habitat conditions and the interrelation with other communities. Finally, the conservation status of the streamlets habitats is analyzed in the context of their importance for the European Natura 2000 network.

Springs: Conserving perennial water is critical in arid landscapes

Arid landscapes are highly water-limited environments and all water (surface and groundwater) is environmentally, culturally and economically important. Springs, sites where groundwater discharges at the Earth's surface, are often the only perennial aquatic environments in arid regions. By providing habitats for aquatic biota, as well being an essential water resource for terrestrial species and human settlements, they are small natural features that make a contribution to ecological processes and biodiversity that extends far beyond their area. Many contain endemic, rare or relictual species of plants, fishes and invertebrates and are recognized as globally important biodiversity hotspots and evolutionary and ecological refugia. However, water resource development and invasive species are major threats to these systems. Future climate scenarios indicate that extended droughts may become more common in some arid regions. Such droughts will increase the pressure to extract groundwater for human uses. Increasing aquifer drawdown will result in the loss of some spring habitats and the endemic and dispersal-limited species they support. Conservation challenges include addressing the additive impacts of water extraction and exotic and invasive species and managing recreational activities. Although the isolation and small size of arid land springs makes them extremely vulnerable to anthropogenic impacts, it also means that protection and management may be more feasible and cost effective than for larger aquatic ecosystems. However, multiple approaches and ongoing actions will be required to address additive impacts. Examples of current conservation measures include fencing to exclude feral herbivores, removal of alien aquatic species and assisted re-colonisation of dispersal-limited, endemic species. The fundamental conservation priority is the protection of the groundwater resource (aquifers) on which arid land springs depend.

The Santa Fe River in northern Florida: effect of habitat heterogeneity on turtle populations

The Santa Fe River (SFR) in northern Florida and its springs provide a unique ecosystem for a wealth of flora and fauna, and support a unique freshwater turtle assemblage. We conducted a 6-year mark-recapture study of ten turtle species to assess how habitat heterogeneity among sites affects riverine turtle populations. Because the SFR ecosystem has not been well described and the major emphasis of this paper is the effect of habitat variation on turtle populations, we provide thorough descriptions of the SFR basin and specific habitats in which we sampled turtles. The SFR originates as a tannin-stained blackwater river, but receives substantial input of clear, alkaline, thermally stable water from numerous artesian springs in its lower reaches. We used mark-recapture and demographic data to evaluate differences in turtle assemblages and population structure on a spatial scale. We compared turtle assemblages between a 5 km reach of blackwater river habitat and a 9 km reach of spring-influenced river habitat. We found the same ten species in both habitats. Hand capture while snorkeling suggested similar relative abundance of species in both river habitats, but baited hoop trap captures suggested that Chelydra serpentina (Snapping Turtle) and Sternotherus minor (Loggerhead Musk Turtle) are proportionately more abundant in the three spring-influenced habitats we sampled. The total density of all turtle species combined appears to be three to four times greater in the spring-influenced river reach than in the blackwater river reach. Examination of population structure of the three most abundant species (Pseudemys suwanniensis [Suwannee Cooter], S. minor, and Trachemys scripta [Yellow-bellied Slider]) in the river and adjacent spring habitats revealed that some springs feeding the SFR may function as nursery habitats. Results demonstrate the importance of habitat diversity (beta diversity) to the riverine turtle assemblage. If we had sampled turtles only in one section of the river or only in spring habitats in the lower SFR, our perceptions of assemblages and population structure would have been vastly different. The fate of the turtle populations in the SFR depends on the quantity and quality of water discharging from its springs. If the long-term trend of declining spring flows continues, we predict that SFR turtle populations will be detrimentally affected in multiple ways such as loss of nursery habitat and reduced recruitment. Less dilution of dark tannic water flowing down from the upper SFR may cause shifts in assemblage and population structure, as well as in population densities. Given the uncertain future of ecological conditions in the SFR, we advocate continued long-term monitoring of this unique turtle assemblage.

COMPARATIVE ANALYSIS OF EPILITHIC DIATOM ASSEMBLAGES OF SPRINGS AND STREAMS IN THE KONJUH MOUNTAIN (BOSNIA AND HERZEGOVINA)

UDK: 574.587:582.26/.27(234.422 Konjuh)
 Springs are recognized as hotspots for freshwater biodiversity conservation. The study objective was to analyze and compare the biodiversity of epilithic diatom communities of spring and stream habitats in the Konjuh Mountain (B&H). The measuring of basic water physical and chemical parameters and diatom sampling were carried out during summer and autumn period in 2013.
 Diatom assemblages were collected from 10 locations: (i) five locations were placed in small mountain springs that flow into headwater streams, where another 5 localities were placed. Diatoms were collected by scrubbing the rocks using standard methodology. Relative diatom cell abundances were established by counting up to 400 frustules on permanent slides prepared in Naphrax.
 Spring habitats were more diverse in diatoms (H' loge =1.67 average) in comparison with headwater stream habitats (H' loge=1.15 average), which was confirmed by t-test (t=2.79; p=0.013). The similarities of community structure from different habitats were investigated by non-metric multidimensional scaling, on the Bray-Curtis similarity matrix in software package Primer 6.
 Using Permutational Manova test, a different diatom composition was proved between spring and stream communities (Pseudo F=2.66, p=0.012), while the seasonal difference in the community structure was not confirmed (F=0.586, p=0.876). The most abundant and frequent species in spring habitats were: Achnanthidium minutissimum (Kützing) Czarnecki, Cocconeis pseudolineata (Geitler) Lange-Bertalot, Gomphonema pumilum var. elegans E.Reichardt & Lange-Bertalot, Meridion circulare (Greville) C.Agardh and Planothidium lanceolatum (Brébisson ex Kützing) Lange-Bertalot. The most frequent and abundant species in headwater stream habitats were: Achnanthidium minutissimum (Kützing) Czarnecki, Cocconeis placentula var. euglypta (Ehrenberg) Grunow, Cocconeis placentula var. lineata (Ehrenberg) van Heurck and Cymbella tridentina Lange-Bertalot, M.Cantonati & A.Scalfi.
 In comparison with streams habitats, the springs are heterogeneous with specific diatom composition due to more stable water flow. Although the springs cover very small areas, the diversity of species that inhabit them must not be neglected in planning the use of these natural resources.

Ecological patterns of water bug (Hemiptera: Heteroptera) assemblages in karst springs: a case study from central Montenegro

Abstract The composition of water bug communities from 32 springs located in the central part of Montenegro was investigated. Twenty five species were identified, including 13 reported as new to Montenegro. The most common species were Hydrometra stagnorum and Velia sp. (Gerromorpha). Our study in the central part of Montenegro revealed that environmental and faunistic classification of karstic springs based on water bug communities may not correspond with each other. According to environmental characteristics, springs were divided into three groups indicating anthropogenic impact on the spring habitats. Water bug communities divided springs into four groups. There are differences in species richness between these four types of water bug assemblages and among the studied spring types. Results of CCA analysis revealed spring size as the main driver of biotic diversity of aquatic bugs in springs. Our study showed that community groups of water bugs specified in the biotic classification of spring habitats are much better defined than assemblages distinguished in the environmental site classification.

A new Navicula (Bacillariophyta) species from low-elevation carbonate springs affected by anthropogenic disturbance

Diatom assemblages in carbonate spring habitats at low elevations, with low discharge, and affected by direct human impacts were studied only recently and in some geographic areas. We describe and characterize the ecology of a new Navicula species from springs with these characteristics within the basin of the River Adige in the south-eastern Alps and Alpine foothills (Province of Verona, Italy). Navicula veronensis sp. nov. is in the group of species around N. cincta but has distinct outline, size, central area, and proximal raphe endings. The availability of data on the distribution of the new species in streams of the Island of Cyprus allowed to quantitatively compare the ecological preferences, niche position, and niche breadth of Navicula veronensis sp. nov. with those of allied species. The new species was found to be characteristic of medium-high conductivity freshwaters, rich in sulphates and chloride, often nitrate enriched and affected by marked discharge fluctuations and seasonal desiccation. Niche position however differed only slightly from those of morphologically-similar species, with the exception of Navicula dealpina that was found to be characteristic of oligotrophic, calcium-bicarbonate rich environments with medium(-low) conductivity. Canonical Correspondence Analysis clearly showed that the most influential environmental variables determining the diatom assemblages of low-elevation carbonate springs affected by anthropogenic disturbance were nitrate enrichment, spring morphology alteration (in particular for water abstraction), and low discharge.

Are aquatic assemblages from small water bodies more stochastic in dryer climates? An analysis of ostracod spring metacommunities

Metacommunity ecology describes community organisation considering both environmental and spatial processes. We tested the relative importance of environmental and spatial factors on spring ostracod assemblages from four European regions characterised by different climatic conditions (e.g. aridity). Pure and shared effects of environment and space were calculated using redundancy analysis and variation partitioning. Both environmental and spatial variables significantly explain assemblage variation, although with different relevance among areas. The amount of variation explained by environmental factors decreased with increasing climate aridity. The reduced size of spring habitats makes them prone to drying events, which are more frequent in dryer climates. Frequent disturbances may lead to local extinctions followed by colonisations from nearby sites, in a source–sink dynamics. Early recolonisation leads to random assemblages and reduces the match between organisms and environmental conditions. As a consequence, a low amount of community variation can be explained by environmental variables. Conversely, the settled communities from wetter climates best fit the ecological characteristics of sites, and deterministic processes, such as species sorting, dominate the assemblages. In conclusion, in the studied regions, ostracod communities from small water bodies of dryer climates seem to be mainly driven by stochastic dynamics when compared to more continental areas.

Going, going, gone? Loss of genetic diversity in two critically endangered Australian freshwater fishes, Scaturiginichthys vermeilipinnis and Chlamydogobius squamigenus, from Great Artesian Basin springs at Edgbaston, Queensland, Australia

Abstract Artesian springs are particularly sensitive freshwater ecosystems, characterized by specialized flora and fauna which, owing to their isolation, are often endemic. Thus, protection of spring habitats and endemic spring biota is important for biodiversity conservation, particularly because human impacts such as invasive species, habitat destruction, and fragmentation can have such devastating effects. This study investigated the mitochondrial DNA (mtDNA) genetic diversity and structure of two critically endangered (IUCN) freshwater fish species: red‐finned blue‐eye Scaturiginichthys vermeilipinnis, and Edgbaston goby Chlamydogobius squamigenus, with the aim of assisting management agencies to establish relocated populations that conserve the genetic integrity and evolutionary potential of both species. 2862 bp from multiple mtDNA genes were amplified from 111 red‐finned blue‐eye individuals (17 from the 1990s and 94 from 2010), and a 660 bp segment of mtDNA cytochrome b was amplified from 111 Edgbaston goby individuals (from 2010). In total, 14 concatenated mtDNA haplotypes were identified in red‐finned blue‐eye and three cytb haplotypes were identified in Edgbaston goby. Overall assessment of the genetic diversity and structure of the endemic fish fauna from the Edgbaston springs revealed low levels of diversity in both species and a loss of haplotypes in red‐finned blue‐eye over time. In addition, both species displayed significant genetic structure: at the spring scale for red‐finned blue‐eye and at the spring group scale for Edgbaston goby. It is concluded that without the appropriate management of relocated populations, such as considering genetic structure and diversity and selecting high quality habitats, these species are at a severe risk of losing evolutionary potential and becoming extinct. This study provides a valuable example for conservation managers of the contribution that population genetic studies can make regarding the adaptive management of endangered species. Copyright © 2016 John Wiley & Sons, Ltd.

Ecological differentiation in planktonic and sediment-associated chemotrophic microbial populations in Yellowstone hot springs

Chemosynthetic sediment and planktonic community composition and sizes, aqueous geochemistry and sediment mineralogy were determined in 15 non-photosynthetic hot springs in Yellowstone National Park (YNP). These data were used to evaluate the hypothesis that differences in the availability of dissolved or mineral substrates in the bulk fluids or sediments within springs coincides with ecologically differentiated microbial communities and their populations. Planktonic and sediment-associated communities exhibited differing ecological characteristics including community sizes, evenness and richness. pH and temperature influenced microbial community composition among springs, but within-spring partitioning of taxa into sediment or planktonic communities was widespread, statistically supported (P < 0.05) and could be best explained by the inferred metabolic strategies of the partitioned taxa. Microaerophilic genera of the Aquificales predominated in many of the planktonic communities. In contrast, taxa capable of mineral-based metabolism such as S(o) oxidation/reduction or Fe-oxide reduction predominated in sediment communities. These results indicate that ecological differentiation within thermal spring habitats is common across a range of spring geochemistry and is influenced by the availability of dissolved nutrients and minerals that can be used in metabolism.

Limno-ecological characteristics and distribution patterns of spring habitats and invertebrates from the Lowlands to the Alps

Springs are autochthonous aquatic ecotones with complex functional properties and heterogeneous eco-morphological structures. Within a small spatial extent, invertebrates are highly diverse and mainly composed of species adapted to the surface–subterranean water interface, the aquatic–terrestrial interface or to the spring habitat itself. In this publication, a first synopsis of limno-ecological case studies of springs from the Lowlands of Schleswig-Holstein, the low mountain ranges of Hesse and Thuringia, the pre-Alps of the Jura Mountains in Switzerland and the Alps in Germany and Switzerland is presented. The field surveys conducted in the different areas focus on an ecological assessment of spring habitats, distribution patterns of the invertebrate fauna and specific regional characteristics. A regional faunistic differentiation of spring-related invertebrate species is evident. A change in the faunistic composition in general and a loss of crenobionts owing to climatic and land-use changes are expected. In addition, it should be noted that long-term monitoring data required to make reliable statements about future developments in the distribution of spring species and to predict habitat conditions are not available.

A global review on ambient Limestone-Precipitating Springs (LPS): Hydrogeological setting, ecology, and conservation

Springs are biodiversity hotspots and unique habitats that are threatened, especially by water overdraft. Here we review knowledge on ambient-temperature (non-geothermal) freshwater springs that achieve sufficient oversaturation for CaCO3 -by physical CO2 degassing and activity of photoautotrophs- to deposit limestone, locally resulting in scenic carbonate structures: Limestone-Precipitating Springs (LPS). The most characteristic organisms in these springs are those that contribute to carbonate precipitation, e.g.: the mosses Palustriella and Eucladium, the crenophilous desmid Oocardium stratum, and cyanobacteria (e.g., Rivularia). These organisms appear to be sensitive to phosphorus pollution. Invertebrate diversity is modest, and highest in pools with an aquatic-terrestrial interface. Internationally, comprehensive legislation for spring protection is still relatively scarce. Where available, it covers all spring types. The situation in Europe is peculiar: the only widespread spring type included in the EU Habitat Directive is LPS, mainly because of landscape aesthetics. To support LPS inventorying and management to meet conservation-legislation requirements we developed a general conceptual model to predict where LPS are more likely to occur. The model is based on the pre-requisites for LPS: an aquifer lithology that enables build-up of high bicarbonate and Ca2+ to sustain CaCO3 oversaturation after spring emergence, combined with intense groundwater percolation especially along structural discontinuities (e.g., fault zones, joints, schistosity), and a proper hydrogeological structure of the discharging area. We validated this model by means of the LPS information system for the Emilia-Romagna Region (northern Italy). The main threats to LPS are water diversion, nutrient enrichment, and lack of awareness by non-specialized persons and administrators. We discuss an emblematic case study to provide management suggestions. The present review is devoted to LPS but the output of intense ecological research in Central Europe during the past decades has clearly shown that effective conservation legislation should be urgently extended to comprise all types of spring habitats.

A Case for Unique Habitat Selection bySigara mathesoni(Hemiptera: Corixidae) in South-Central Pennsylvania

Abstract Sigara mathesoni (Hemiptera: Corixidae), which predominantly inhabits the northern United States and Canada, has recently been found in carbonate streams with stable and cold temperature regimes in south-central Pennsylvania. The focus of this research was to determine if there is a difference in occurrence of S. mathesoni between carbonate and non-carbonate streams, and whether abiotic factors within these habitats can be used to explain or predict its regional distribution. Our results suggest that S. mathesoni predominantly occurs in carbonate spring habitats, and that parameters such as alkalinity and daytime summer water temperature may best predict occurrence. This work validates observations in other literature and supports the hypothesis that S. mathesoni is a rare species in Pennsylvania and possibly throughout its southern range.

Larval morphology of the Western Balkans endemic caddisflies Drusus krusniki Malicky 1981, D. vernonensis Malicky 1989, and D. vespertinus Marinković 1976 (Trichoptera, Limnephilidae, Drusinae).

Drusinae (Trichoptera, Limnephilidae) are highland caddisflies inhabiting high-gradient, turbulent running water and spring habitats. They are disjunctly distributed over the Eurasian mountain ranges, and the majority of species is endemic to particular mountain areas. The most diverse of three main groups of the Drusinae, the grazer clade, consists of species in which larvae feed on epiltihic biofilm and algae. In this paper we describe three previously unknown grazer-clade Drusinae larvae: Drusus krusniki Malicky 1981 (endemic to the Dinaric western Balkans), D. vernonensis Malicky 1989 (endemic to the Hellenic western Balkans), and D. vespertinus Marinković 1976 (endemic to the Dinaric western Balkans). The larvae of these species have toothless mandibles typical of the Drusinae grazer clade. Larvae and adults were unambiguously associated using molecular genetic data, i.e., the mitochondrial cytochrome oxidase I gene fragment (mtCOI3-P). Morphological characteristics of the larvae are described and the diagnostic features enabling species-level identification are illustrated. We further discuss the ecology and distribution of three Western Balkan endemic species.

Phylogeography and evolution of the Red Salamander (Pseudotriton ruber)

Phylogeographic studies frequently result in the elevation of subspecific taxa to species given monophyly, or the synonymy of subspecies that are not monophyletic. However, given limited or incongruent datasets, retention of subspecies can be useful to describe hypothesized incipient species or to illustrate interesting biological phenomena driving morphological diversity. Four subspecific taxa have been used to describe largely allopatric geographic variation within the species Pseudotriton ruber, a plethodontid salamander occupying stream and spring habitats across eastern North America: P. r. vioscai occurs in lowland Coastal Plain habitats, while P. r. ruber, P. r. nitidus, and P. r. schencki occupy upland regions in and around the Appalachian Mountains. Pseudotriton ruber co-occurs through its distribution with the aposematic newt Notophthalmus viridescens, and both species are hypothesized to be part of a Müllerian mimicry complex. In this study, we sequenced regions of two mitochondrial (cytochrome b, NADH dehydrogenase subunit 2) and one single copy nuclear protein-coding gene (pro-opiomelanocortin) from individuals sampled across much of the distribution of P. ruber and then used maximum-likelihood and Bayesian phylogenetic inference to test the monophyly of subspecies, reconstruct biogeographic history, and make inferences about morphological evolution. Phylogeographic hypotheses from mitochondrial and nuclear datasets described structure among populations of P. ruber which separated Coastal Plain and upland Appalachian populations, but subspecies were not monophyletic. Biogeographic reconstruction estimated the ancestor of all populations to have occupied and initially diverged in the Coastal Plain during the Pliocene (∼3.6mya), before one lineage subsequently invaded upland areas of Appalachia. Bold bright coloration of high elevation subspecies P. r. nitidus and P. r. schencki appears to have evolved twice. We hypothesize that the Müllerian mimicry complex with N. viridescens and P. ruber may provide a selective mechanism driving the co-evolution of striking bright and dull morphological variation among populations of both species. While P. ruber subspecies were not consistent with our criteria for diagnosing species (monophyly) and therefore could not be elevated to species, we advocate for the retention of subspecies because they describe hypotheses about an incipient species (P. r. vioscai) and how Müllerian mimicry may shape morphological diversity of species.

Ecological patterns of Chironomidae assemblages in Dynaric karst springs

Springs are one of important freshwater habitats in the Dynaric Mountains. Nevertheless, there were no intensive studies on dipteran communities in the region. Here we present an ecological analysis of Chironomidae communities recorded from a set of 27 springs along the Cvrcka River mainstream (the Republic of Srpska, Bosnia and Herzegovina). Environmental classification of Cvrcka springs divide them into three groups reflecting the level of human impact. Chironomidae communities divide investigated springs into three groups more dependent on bottom substrate quality. CCA indicates that the hard bottom and altitude are primary (significant) factors determining midge assemblages. Secondary factors influencing communities are oxygen concentration and conductivity. There are clear differences in diversity and abundance in these three types of spring communities. Type II aggregates natural sites for Cvrcka valley. Samples characterized by high abundance of Chironomus seems to be an outliers in Cvrcka canyon. Eucrenon and hypocrenon communities are distinct, but no differences in the diversity level or the environmental assemblage relation were recorded for both mesohabitats. This study proves that solely environmental classification of spring habitats reflects well human impact, but invertebrate communities may not clearly follow general classification, reacting to a set of natural and altered conditions.

Sedimentary evolution and persistence of open forests between the south-eastern Alpine fringe and the Northern Dinarides during the Last Glacial Maximum

Abstract We present a paleoenvironmental reconstruction for the mountain fringe between the South-Eastern Alps and the Northern Dinarides (NE-Italy/W-Slovenia) during the Last Glacial Maximum. We focused on a new sedimentary and paleoecological archive spanning the LGM acme, located in an aggrading, permanently flooded and ponded plain, dammed by an active fluvioglacial megafan. The ecosystem reconstruction, based on two high resolution pollen records, is supported by a rich plant macrofossil flora and constrained by a robust radiocarbon chronology between 26 and 22 cal ka BP. We show evidence for persistence of boreal trees and of different open boreal forest types throughout the LGM at the south-eastern mountain fringe of the Alps and the Northern Dinarides. Fire frequency is responsible for high, oscillating forest openness. The paleobotanical record is discussed in the light of the ecogeographic diversity of the region. A belt formed by Swiss stone pine, larch and dwarf mountain pine on limestone bedrock, and accompanied by Spruce in the floodplain, extended uphill, while proximal outwash plain supported Scots pine and dwarf mountain pine. These differences arise from groundwater regimes rather than from local climate variability. A steep moisture gradient from the semiarid pedoclimatic regime prevailing in the Adriatic alluvial plain to the forested mountain fringe is related to the orographic rainout triggered by southern air circulation. Mesophytic broad-leaved forest trees did not withstand the LGM temperature extremes in zonal ecosystems at the Alpine–Dinaric fringe; however, the fossil evidence suggests a number of microrefugia in karstic and thermal spring habitats of the northern Adriatic.

Exploring copepod distribution patterns at three nested spatial scales in a spring system: habitat partitioning and potential for hydrological bioindication

&lt;p&gt;In groundwater-fed springs, habitat characteristics are primarily determined by a complex combination of geomorphic features and physico-chemical parameters, while species assemblages are even more intricate. Springs host species either inhabiting the spring mouth, or colonizing spring habitats from the surface or from the aquifers which feed the springs. Groundwater species living in springs have been claimed as good candidates for identifying dual aquifer flowpaths or changes in groundwater pathways before reaching the spring outlets. However, the reliability of spring species as hydrological biotracers has not been widely investigated so far. Our study was aimed at analysing a large karstic spring system at three nested spatial scales in order: i) to assess, at whole spring system scale, the presence of a groundwater divide separating two aquifers feeding two spring units within a single spring system, by combining isotope analyses, physico-chemistry, and copepod distribution patterns; ii) to test, at vertical spring system scale, the effectiveness of copepods in discriminating surface and subsurface habitat patches within the complex mosaic spring environment; iii) to explore, at local spring unit level, the relative role of hydrochemistry and sediment texture as describers of copepod distribution among microhabitats. The results obtained demonstrated the presence of a hierarchical spatial structure, interestingly reflected in significant differences in assemblage compositions. Copepod assemblages differed between the two contiguous spring units, which were clearly characterized by their hydrochemistry and by significant differences in the groundwater flowpaths and recharge areas, as derived by the isotope analyses. The biological results suggested that stygobiotic species seem to be related to the origin of groundwater, suggesting their potential role as hydrological biotracers. At vertical scale, assemblage composition in surface and subsurface habitats was significantly different, both between spring units and among microhabitats, supporting strong habitat preferences of copepod species. At the smaller local scale, the response to habitat patchiness of subsurface copepod assemblages resulted in distribution patterns primarily defined by sediment texture, while the sensitivity to differences in hydrochemistry was negligible.&lt;/p&gt;

Environmental factors determining growth of salamander larvae: A field study

Abstract Larval growth and survival of organisms are strongly influenced by abiotic and biotic factors, as demonstrated by experimental studies performed under controlled laboratory or semi-natural conditions. Even if they have many advantages, experiments cannot cover the full complexity of natural conditions and field studies are needed for a better understanding of how environmental variation determines growth and development rate. Fire salamander Salamandra salamandra females give birth to larvae in a variety of habitats, both epigean and subterranean. In caves, salamander larvae successfully grow and metamorphose, but their growth is more than three times longer than in epigean streams and factors determining these differences require investigation. We performed a field study to understand the factors related to the growth of fire salamander larvae in different environmental conditions, evaluating the relationship between environmental features and larval growth and differences between caves and epigean spring habitats. Both caves and epigean larvae successfully grew. Capture-mark-recapture allowed to individually track individuals along their whole development, and measure their performance. Growth rate was significantly affected by environmental variables: larvae grew faster in environments with abundant invertebrates and few conspecifics. Taking into account the effect of environmental variables, larval growth was significantly lower in caves. Food availability plays a different effect in the two environments. Larval growth was positively related to the availability of invertebrates in epigean sites only. The development rate of hypogeous populations of salamanders is slower because of multiple parameters, but biotic factors play a much stronger role than the abiotic ones.

Cyanobacteria in ambient springs

Although neglected for a long time by freshwater-ecology research, springs are very important habitats for biodiversity conservation. They are multiple ecotones, and are characterized by a remarkable variety of environmental conditions (e.g., from highly-shaded to UV exposed, from permanent discharge to intermittent flow, from still water to strong currents, from extremely-soft to carbonate-precipitating water, etc.). Moreover, springs are often amongst the last high-integrity, oligotrophic freshwater habitats in densely populated areas. Because of the high quality of their waters, the main impact affecting springs is capturing and water diversion. Climate-change driven reduction in precipitations in many areas is likely to determine an aggravation of this impact. It is thus important to document the rich and peculiar biodiversity of springs, also to establish reference conditions for bioassessment methods. Especially in non-acidic springs with running water, and coarse lithic substrata, cyanobacteria are often one of the most taxa-rich and abundant groups of photoautotrophs. The relatively-scarce information available in the literature is mostly referred to similar habitats, and not to spring habitats in the narrower sense. Papers dealing with the cyanobacteria of ambient springheads (=eucrenal) worldwide are still very rare. These were reviewed separating ambient springs in temperate and warm climate, and with special attention to key species, to cyanobacterial strategies allowing survival in oligotrophic headwaters (e.g., nitrogen fixation, phosphatases, anti-UV compounds, etc.), and to distribution patterns. The review also hopes to bolster new interest and research on this topic, and suggests some promising research directions.

大兴安岭驯鹿（Rangifer tarandus）的春季生境选择

PDF HTML阅读 XML下载 导出引用 引用提醒 大兴安岭驯鹿(Rangifer tarandus)的春季生境选择 DOI: 10.5846/stxb201401120087 作者: 作者单位: 中央民族大学 生命与环境科学学院,中央民族大学 生命与环境科学学院,中央民族大学 生命与环境科学学院,中央民族大学 生命与环境科学学院,中央民族大学 生命与环境科学学院,内蒙古师范大学 生命科学与技术学院,内蒙古根河市农牧局,中国人民大学 作者简介: 通讯作者: 中图分类号: 基金项目: 国家科技支撑计划专题(2013BAC09B02-6); 高等学校学科创新引智计划(B08044) The spring habitat selection of reindeer (Rangifer tarandus) in Great Xing'anling of China Author: Affiliation: College of Life and Environment Sciences,Minzu University of China Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:为确定分布于我国大兴安岭西北麓的濒危驯鹿(Rangifer tarandus)的春季生境选择特征,于2012和2013年的3-4月间,采用样线样方结合的生境调查方法,对内蒙根河驯鹿的春季偏好生境和对照生境进行了取样,并对样方的海拔和乔木郁闭度等23个生境变量进行了计测与分析。结果表明:与非利用样方(n=132)相比,驯鹿春季偏好生境(n=79)的海拔((957.27 ±1.68) m)、乔木郁闭度((32.84±2.72)%)、乔木密度(21.72±1.52)、地表植被盖度((85.06±1.03)%)、树桩数(6.81±0.45)和倒木数(5.73±0.54)均显著较大(Mann-Whitney U test, P<0.05),而灌木盖度((57.95±2.79)%)、枯草盖度((33.11±2.79)%)、乔木高度((9.58±0.27) m)和灌木均高((59.85±2.69) cm)显著较小(Mann-Whitney U test, P<0.05),而且驯鹿春季趋向于选择西坡和南坡(77.21%)的坡度较缓(93.67%)、位于坡中下位(67.09%)的生境,并偏好选择针叶林(68.35%)中的隐蔽度好(82.28%)、避风状况良好(64.56%)、湿润(60.76%)、距水源较近(≤1000 m,94.94%)及距人为干扰较远(≥1000 m,87.34%)的生境(Chi-Square test, P<0.05)。此外,驯鹿偏好生境的变量主成分分析结果表明,坡位、乔木特征(乔木胸径和乔木高度)、食物多度(灌木盖度、倒木数及树桩数)、雪被特征(雪深、雪盖度和郁闭度)、干扰强度(距人为干扰距离)、植被类型(坡向和植被类型)是影响驯鹿春季生境选择的重要因素,综合体现了驯鹿在春季对保温、食物和安全性的需求。 Abstract:The reindeer (Rangifer tarandus) has been a wildlife resource used extensively by local people across its range for thousands of years. In China, the reindeer occurs only in the northeastern part of the Great Xing'anling area in Inner Mongolia. The Owenki people in this area have long exploited the reindeer for its hide, meat, velvet antlers, and milk, showing its economic importance. However, the reindeer has fallen into the critically endangered status, with only about 800 left in its native range. There have been some publications addressing biological and ecological characteristics of the Chinese reindeer, but most of them have been anthropological and ethnological studies of anecdotal character. To date, there has been no study on the habitat selection of reindeer. To implement an in situ conservation program for increasing its population, it is critical to study habitat selection of the reindeer in China. The purpose of this paper is to present quantitative survey results of the reindeer's spring habitat selection in China and to explore the key factors influencing its habitat utilization. Thereby, implications for conservation measures to be implemented are discussed. In March and April of 2012 and 2013, habitat selection of the reindeer was surveyed in the Genhe area of northeastern China using line-transect surveys. A total of 23 habitat factors were measured and compared for 211 sample plots, in which 79 plots were designated as used-plots and 132 as non-used plots. The results indicated that reindeer in Genhe area preferred to select spring habitats at higher altitude ((957.27±1.68) m), with higher tree canopy ((32.84±2.72)%), tree density ((21.72±1.52) per 400 m2), increased ground-plant cover ((85.06±1.03)%), stump quantity (6.81±0.45), and fallen-wood quantity (5.73±0.54), but with lower shrub canopy ((57.95±2.79)%), withered-grass cover ((33.11±2.79)%), tree height ((9.58±0.27) m), and shrub height ((59.85±2.69) cm), compared to the non-used habitat plots. Moreover, the reindeer also selected habitats with intermediate to low slope (67.09%) on the south and west slopes (77.21%), which were located mainly in conifer forests (68.35%) and provided relatively good concealment (82.28%), more protection from wind (64.56%), relative proximity to water sources (< 1000 m, 94.94%), and were farther away from human disturbance (<1000 m, 87.34%). The principal component analysis showed that slope position, tree characteristics (tree height and tree diameter at breast height), food abundance (shrub cover, number of fallen wood, and stump number), snow characteristics (snow depth, snow cover, and tree canopy), disturbance intensity (distance from human influence), and vegetation type (slope aspect and vegetation type) were most important in determining the spring habitat selection of the reindeer. In summary, the results indicated that the reindeer's habitat selection in the spring was a multidimensional process through which the reindeer could adapt to local ecological conditions of temperature, food abundance, shelter, water supply, and ground cover. Furthermore, the reindeer in China has not yet been domesticated, and it is necessary to introduce conservation methods for its protection since it is critically endangered species. 参考文献 相似文献 引证文献