Stony Substrates Research Articles

Detection of Stones in Marine Habitats Combining Simultaneous Hydroacoustic Surveys

Exposed stones in sandy sublittoral environments are hotspots for marine biodiversity, especially for benthic communities. The detection of single stones is principally possible using sidescan-sonar (SSS) backscatter data. The data resolution has to be high to visualize the acoustic shadows of the stones. Otherwise, stony substrates will not be differentiable from other high backscatter substrates (e.g., gravel). Acquiring adequate sonar data and identifying stones in backscatter images is time consuming because it usually requires visual-manual procedures. To develop a more efficient identification and demarcation procedure of stone fields, sidescan sonar and parametric echo sound data were recorded within the marine protected area of “Sylt Outer Reef” (German Bight, North Sea). The investigated area (~5.900 km2) is characterized by dispersed heterogeneous moraine and marine deposits. Data from parametric sediment echo sounder indicate hyperbolas at the sediment surface in stony areas, which can easily be exported. By combining simultaneous recorded low backscatter data and parametric single beam data, stony grounds were demarcated faster, less complex and reproducible from gravelly substrates indicating similar high backscatter in the SSS data.

Early vegetation succession on gravel bars of Czech Carpathian streams

Rivers with a natural flooding regime and gravel accumulations are an important natural habitat endangered by regulations and other types of human impact. Succession after disturbances by floods creates a mosaic of different vegetation types, some of them containing rare specialist species. We studied vegetation succession and changes in plant diversity on river gravel bars of four streams in the Western Carpathians and their foothills in the eastern Czech Republic. This area experienced extreme 50-year flood event in May 2010. Gravel bar vegetation was destroyed, some of the former bars were covered by sediments, and some new bars arose. We sampled gravel bar vegetation two months after the floods and repeated the sampling on each site during the next three years. Initial vegetation has developed through a sparse and species-rich stage into denser stands with more shade-tolerant species. In the fourth year, tall herbs, such as Urtica dioica, Phalaris arundinacea and the alien Impatiens glandulifera, dominated the communities, but shrub vegetation started to develop only in a few places. Species capable of vegetative dispersal prevailed over species dispersed by seeds only. Altitude and size of gravel/stone particles were identified as important factors affecting vegetation succession. The succession ran faster on gravelly substrates at lower altitudes than on stony substrates at higher altitudes. Although the studied streams are partly influenced by human interventions and host only few gravel bar specialists, they are of considerable conservation importance.

New data on distribution and ecology of rare in the Khanty-Mansi Autonomous District (Western Siberia) moss species (Bryophyta)

New locations of 25 rare species of mosses, known earlier in the Khanty-Mansi Autonomous District from one or a few locations, are provided. Their ecology, phytocenotic affinity and peculiarities of the distribution on the territory of the autonomous district and taiga zone of the Western Siberia as a whole are discussed. A high proportion of rare species in the moss flora of the central part of the taiga zone of Western Siberia resulted from limited distribution or absence of suitable habitats associated with stony substrates and outcrops of groundwater rich in mineral nutrition elements, as well as from intermediate (ecotone) position of the flora on the latitudinal bioclimatic gradient from south to north.

The longitudinal pattern of crustacean (Peracarida, Malacostraca) assemblages in a large south European river: bank reinforcement structures as stepping stones of invasion

The spread of alien crustaceans has significantly contributed to the homogenization of macroinvertebrate fauna of European freshwaters. However, little is known about alien Peracarida crustaceans of the Sava River, which represents the most important corridor for the spread of invasive species into Dinaric rivers with highly endemic fauna. In this study, we investigated Peracarida (Amphipoda, Isopoda and Mysida) collected during three years (2011, 2012 and 2015) from a total of 61 sites along the entire course of the Sava River. Besides describing the longitudinal pattern of Peracarida assemblages, we tested the hypothesis that bank reinforcement structures facilitate peracarid invasions by comparing densities and assemblages on natural and artificial substrate at 15 sites. In a total, 14 peracarid crustacean species (5 native and 9 alien) were recorded. The Upper third of Sava was inhabited by native peracarids only, while the Middle and Lower Sava were dominated by alien species. The invasive amphipods Dikerogammarus haemobaphes, Chelicorophium sowinskyi and Chelicorophium curvispinum, and invasive isopod, Jaera istri, were the most abundant species along the middle course. Densities of alien peracarids in the Middle Sava were the highest and their share in macroinvertebrate assemblages was very variable, while the Lower Sava had the highest number of alien species in low densities. The densities of alien amphipods and isopods were in most cases significantly higher on bank reinforcement structures than on natural substrate. Therefore, artificial stony substrates act as stepping stones of invasion for alien peracarids and largely contribute to their success in large lowland rivers.

Rock outcrops in the southeastern part of the West Siberian plain as the northern limit of distribution and refuge of rare moss species

Foothill plains along the northwest periphery of Altai–Sayan Mountain Country are the northern limit of stony substrates in the West Siberian longitudinal sector. Rock outcrops in this area are rare; their areas usually do not exceed few dozens of square meters. Despite small areas, the rocky outcrops keep nearly half of the foothill moss flora. 119 moss species were recorded in the rocky habitat; 26 of them are rare both in Western Siberia and in its mountain ringing. An annotated list of species is given. Features of species distribution in the longitudinal sector of West Siberia are discussed.

Differential responses by stream and riparian biodiversity to in‐stream restoration of forestry‐impacted streams

Summary Forestry can have detrimental impacts on stream ecosystems, particularly via excessive sedimentation. A key challenge to stream management is therefore to identify the best restoration practices to mitigate the harmful impacts of fine sediments on stream biodiversity and ecosystem functioning. We studied the effects of restoration of sediment‐impacted headwater streams on the habitat structure, hydrologic retention, biodiversity (microbes, bryophytes, benthic macroinvertebrates, riparian plants) and ecosystem functions (periphyton accrual rate and leaf breakdown) by comparing four treatments: wood‐restored, boulder‐restored, impacted (by fine sediments) and near‐natural streams. The restored streams were sampled 3–7 years post‐restoration. Restoration by wooden or boulder structures aimed to reduce deposited sediments and increase channel heterogeneity and hydraulic retention. Wooden structures were ineffective in removing fine bed sediments and did not induce positive responses in aquatic biota. Boulder additions reduced substrate limitation and thereby proved beneficial for aquatic bryophytes. Benthic macroinvertebrates were clearly impaired by sedimentation but responded weakly to restoration. Leaf‐decomposing microbes and ecosystem functions were unresponsive to restoration but neither did they differ between near‐natural and impacted streams, suggesting that they were little harmed by sedimentation. Wood addition enhanced hydraulic retention, and riparian plant assemblages along wood‐restored streams resembled those in near‐natural streams, suggesting that increased retention re‐established a more natural flood regime. By contrast, riparian plant assemblages in boulder‐restored streams did not differ from those in impacted streams. Synthesis and applications. Restoration improved several aspects of stream and/or riparian biodiversity, but had limited effects on ecosystem functions. Different restoration measures resulted in differing biodiversity outcomes: boulder addition was more effective at restoring in‐stream heterogeneity and aquatic biodiversity, whereas wooden structures helped restore channel hydrology and retentiveness, and, consequently, riparian vegetation. Therefore applying both measures in the restoration of forested headwater streams with naturally stony substrates enhances stream habitat variability at the watershed scale, providing the most promising scenario for biodiversity benefits in broad‐scale restoration designs. In‐stream restoration that increases hydraulic retention has impacts that extend beyond ecosystem boundaries, reinforcing the need to restore, manage and protect streams and their riparian forests in an integrated effort.

Nuevos registros con notas ecológicas y taxonómicas de esponjas dulceacuícolas (Porifera, Spongillidae) en la cuenca del Duero

This work is a contribution to the knowledge of freshwater sponges (Porifera, Demospongiae, Spongillidae) of the Douro River watershed. Specimens were found in 24 of 32 transects in 16 sampling stations. Distribution and several ecological data were obtained in 25 wadeable river transects (20+/5−) and 7 deep lakes (4+/3−) of six sub-basins of the northern Iberian plateau. Four species ( Ephydatia fluviatilis, E. muelleri, Heteromeyenia baileyi and Spongilla lacustris ) were recorded throughout the survey during successive dry sessions and classified by microscopic observation of siliceous sclera. The maximum species richness was found in the Negro River, where sympatric coexistence was detected in three species. E. muelleri was only found in the Aliste River, and it is the first record of this species in the Douro basin. H. baileyi showed a preference for shallow areas in flowing waters, and was only present on hard stony substrates (quartzites). S. lacustris and E. fluviatilis were found on compacted sediments, rocks and submerged wood substrates, and in a wide interval of depths. E. fluviatilis was absent in mountain lakes, whereas it was the most frequent species in rivers. H. baileyi and S. lacustris showed preference for acidic and low mineralization rivers, while both species of Ephydatia for more mineralized waters. The influence of chemical water and other environmental parameters on the distribution range of each species and its presence in syntopy with other invertebrate indicators of oligotrophic conditions, acidity and high oxygenation in water is remarked.

Phenotype diversity and phylogeny of selected Scytonema-species (Cyanoprokaryota) from SE Brazil.

Members of the genus Scytonema belong to prominent components of microflora of tropical and subtropical soils, but their diversity and taxonomic classification is still little known. Molecular analyses of isolated strains, but also the morphological and ecological examination of natural populations are important for the starting revisions. Here we present phenotype characteristics of fourteen morphotypes of the cyanobacterial genus Scytonema from the SE Brazil, mostly from the state Sao Paulo and from the Atlantic Rainforest (ecosystem of Mata Atlântica). The populations of studied Scytonema species are ecologically significant, as they hold the dominant position in the microvegetation communities of lateritic and forest soils and of stony substrates (less frequently also aquatic forms). Species commonly distributed throughout the tropical regions (such as S. guyanense, S. javanicum, S. stuposum), as well as the types with restricted geographic distribution in S America are included in the study. Two new species from a little known subgenus Myochrotes, in which the cultivation is difficult, are described: S. papillicapitatum Sant´Anna et Komarek and S. chorae Sant´Anna et Komarek. Our analyses support the principle of congruency of morphological characters with phylogenetic position of the studied species.

Current and substrate preferences of benthic invertebrates in the rivers of the Hindu Kush-Himalayan region as indicators of hydromorphological degradation

The study introduces an approach to obtaining information about the preferences of benthic invertebrates for substrate and current velocity in a region with little prior knowledge of benthic invertebrates. These preferences are then used for river assessment. Substrate-specific sampling of 271 reference sites was conducted in lower mountainous and lowland areas of the Hindu Kush-Himalaya region. Statistical analysis revealed significant preferences for substrate type and current velocity for 50 taxa of Ephemeroptera, Plecoptera, Trichoptera, Coleoptera, Diptera, Odonata, Mollusca, and Oligochaeta. A 20-point system was developed to assign scores for substrate and current preferences. Scores from seven taxa of Ephemeroptera and Trichoptera revealed low ecological potential in response to habitat alteration. These data were used to develop four preference metrics. The Lithal metric is composed of 34 taxa with significant preferences for stony substrates (fine gravel to bedrock size). The Lithophile metric contains 21 taxa with strong statistical links to stony substrates, which were also found on other substrates. The Lithobiont metric consists of 13 taxa exclusively found on stones. The Lotic metric consists of 11 taxa with significant preferences for moderate-to-fast current velocities. Multi-habitat sampling was conducted at 181 sites reflecting a hydromorphological gradient. The Mann–Whitney U test and box-and-whisker plots were applied to test the relationship of the new metrics to hydromorphological stress. Of the four new metrics, the Lithal, Lithophile, and Lotic were able to detect impacts of hydromorphological degradation.

A test of the association between Lake Habitat Quality Assessment and macroinvertebrate community structure

Abstract Lake Habitat Survey (LHS) provides a standard method for characterizing the physical habitat of lakes and reservoirs, but has not been tested for its relevance to the composition and abundance of macroinvertebrates. This study investigated the relationship between the metrics used in LHS and components of macroinvertebrate communities found in the littoral zone of a shallow calcareous lake in the west of Ireland. A scoring system, the Habitat Quality Assessment (HabQA), developed from the Lake Habitat Quality Assessment (LHQA) of the LHS, was used to assess the relationship between habitat quality based on physical structure within 10 LHS ‘habplots’ and metrics of the macroinvertebrate community. Macroinvertebrate taxon richness, both of adults found in the riparian zone and larvae found in the littoral zone, correlated positively with the HabQA score. Macrophytes within the littoral zone, and complexity of riparian vegetation within the riparian zone, were particularly important in driving the HabQA score. While overall abundance of macroinvertebrates did not vary with HabQA score, that of particular genera did. The HabQA score was a useful surrogate of taxon richness for adult and larval aquatic macroinvertebrates, suggesting that, in general, LHS provides a useful conservation assessment tool relevant for macroinvertebrates. However, in some circumstances, such as wave‐washed stony substrates devoid of macrophytes, the HabQA score may not capture the quality of a site for macroinvertebrates, and the importance of natural but low diversity sites should not be neglected in conservation assessment of lakes. Similarly, while the LHS method notes the presence of alien species, further work on how these could be incorporated into the method would be useful. Reliance on a single, or overall combined, metric score across quality elements, whether based on biotic or structural assessment, has some potential limitations. It is clear that for conservation management a holistic assessment of naturalness, representativeness and species rarity needs to be made in conjunction with scoring systems. Copyright © 2009 John Wiley & Sons, Ltd.

Characterisation of juvenile flatfish habitats in the Baltic Sea

Survival and growth of the earliest life-stages is considered a key factor in determining the abundance of many marine fish species. For flatfishes, the availability of high quality nursery areas is essential for successful recruitment. Regarding the Baltic Sea, there are large gaps in knowledge on factors that influence the distribution of flatfishes during this sensitive stage. To identify the characteristics of important nursery areas in the Baltic for flounder ( Platichthys flesus) and turbot ( Psetta maxima), a field survey with push net sampling was conducted in the northern Baltic proper during autumn 2006. The sampling stations were stratified to cover several different habitat types defined by substrate and wave exposure. Apart from density of young-of-the-year (YOY) flatfishes, a number of ecological characteristics of the habitat were recorded. Physical habitat variables included substrate type, salinity, depth, turbidity, vegetation and habitat structure. Variables describing biotic processes, such as prey availability and abundance of competitors, were also sampled. The relationships between the spatial distribution of species and these ecological characteristics were fitted to presence/absence data of juvenile flatfish using generalized additive models (GAM). The best habitat descriptors for flounder in order of contribution were: substrate, habitat structure, salinity, wave exposure and occurrence of filamentous algae. Positive effects of increasing wave exposure, salinity and structure were detected while a high cover of filamentous algae had a negative effect. Sand and gravel were preferred over soft and stony substrates. For turbot the best habitat descriptors in order of contribution were: occurrence of filamentous algae, substrate and turbidity. Turbot showed a preference for areas with a low cover of filamentous algae, high turbidity and sandy substrate. Prey availability and abundance of competitors were not included in the models, indicating that the distribution of flatfishes at the scales studied (tens of kilometres) is mainly governed by physical habitat properties. These results constitute the basis for future efforts on mapping of essential flatfish habitats in the Baltic Sea.

The epilithic algal assemblages of Lake Kinneret, Israel

We studied for the first time the effects of geological substrates on taxonomic composition of epilithic algal assemblages in Lake Kinneret and their seasonal fluctuations. It is shown that both species richness and cell densities increase during the winter. Among the fifty-four species identified, the major groups were Bacillariophyta, Chlorophyta, and Cyanobacteria (41%, 37%, and 16%, respectively). The dominant alga on stony substrates throughout the study period was the diatom Gomphonema sp., accompanied by Cymbella sp., Navicula spp., and Nitzschia spp. The Chlorophyta were represented by Cladophora glomerata (Linnaeus) Kutzing, Tetraedron minimum (A. Braun) Hansgirg, and the Cyanobacteria by Lyngbya sp. The substrate effect on algal growth was also determined. The results show that 66%, 20%, and 14% of all epilithic algae were found on limestone, basalt, and flint, respectively. In the depth profile, two peaks of epilithic algae were revealed. The first was found at 0.25-0.70 m, dominated by the Bac...

Using Baetidae Species as Biological Indicators of Environmental Degradation in a Brazilian River Basin

The Ephemeroptera family Baetidae is one of the most specious families in the Neotropical region and a great effort to improve the taxonomy of this group has been made over the last 10 years in South America. Such studies now enable the development of biomonitoring tools at species-level in the region. A total of 2,199 baetids were collected from seven sampling sites, collected three times (autumn, winter and summer), representing an environmental gradient, draining an area of Atlantic Forest remnants. We describe the mesohabitat of nine Baetidae species and evaluate their responses to environmental degradation and water chemistry by means of biological measures (richness and abundance) and multivariate analysis (Canonical Correspondence Analysis), in order to assess their potential capacity as indicators of these impacts. Most species were found predominantly associated with stony substrates, but some were associated with pool litter, and one species was found predominantly in riffle litter substrate. Species distribution was influenced by the environmental gradient. Based on the CCA ordination, we were able to identify which species were found in pristine versus the most impaired areas, therefore enabling us to establish the sensitivity of each species.

Accumulation of Endosulfan in Wild Rat, Rattus Norvegious as a Result of Application to Soya Bean in Mazoe (Zimbabwe)

The sensitivity of eleven metrics using macroinvertebrate assemblages were evaluated in an environmental gradient in a tropical river in south-east Brazil. Eight sites were sampled in an altitudinal range of 160-650 m.a.s.l. during 1999 (April and August) and 2000 (February). Four substrates were sampled at each site: riffle litter, pool litter, stony substrates and sediment. Correspondence Analysis indicated that assemblages were primarily more influenced by physical changes (like deforestation and erosion processes) than the water chemistry. The sensitivity of each metric was evaluated through the application of box-and-whisker plot method by its power to assess impairment (metrics should be able to discriminate reference sites from impaired sites) and natural variability (metrics should not discriminate two reference sites). Metrics that failed in at least one of the above premises were not considered as sensitive. In this study, the most sensitive metrics were Shannon index, BMWP-ASPT, %_EPT, and relative abundance of EPT to Chironomidae.

WHITE-CLAWED CRAYFISH IN MUDDY HABITATS: MONITORING THE POPULATION IN THE RIVER IVEL, BEDFORDSHIRE, UK

White-clawed crayfish Austropotamobius pallipes are usually associated with stony substrates, tree roots, or refuges in submerged banks. The River Ivel has the last known population of white-clawed crayfish in Bedfordshire. Prior to 2005, much of the bed comprised uniform silt, plus leaf-litter. Stands of reedmace Typha latifolia and other emergent vegetation were localised in less shaded areas. Initial survey results suggested a population at low abundance. A low-cost monitoring strategy was started in 2001 and continued three times a year to 2005, using engineering bricks, which offer artificial refuges. Crayfish are counted when bricks are lifted periodically. De-silting of c. 430 m river was carried out in February 2005, to improve habitat and to maintain the flood capacity in the channel upstream of a mill weir. Additional bricks were deployed a few weeks in advance of de-silting, then bricks and crayfish were lifted prior to dredging and were returned the next day. Starting upstream, soft, wet mud was dredged out, placed on the bank and searched manually for crayfish. Banks, tree roots and shallow margins were left undisturbed. In all, 4,142 crayfish were found in dredgings from a 430 m length of the mid channel. Crayfish were strongly associated with emergent vegetation, but many were present below the surface of the silt. Crayfish released in the dredged channel immediately burrowed into the silt retained on the channel margins. Monitoring after dredging showed no change in abundance in the main area with in-bank refuges and lots of bricks, but there was an increase in occupancy of bricks in an area where most crayfish had been in emergent vegetation.

Influence of water chemistry and environmental degradation on macroinvertebrate assemblages in a river basin in south-east Brazil

Benthic macroinvertebrate assemblages, water chemistry variables and environmental degradation were investigated in an Atlantic Forest region in Brazil. Seven sites of the Guapimirim river basin were studied during three sampling periods based on the rain regime: end of wet season (May 1998), dry season (August 1998), and wet season (January 1999). Four substrates were collected at each site: sand, stony substrates, litter in pool areas and litter in riffle areas. Relationships between macroinvertebrate assemblages, water chemistry variables and environmental degradation were examined using canonical correspondence analysis (CCA). According to CCA, concentrations of dissolved oxygen and chloride, and the environmental degradation, measured by the Riparian Channel Environment index, exhibited the strongest relationship to macroinvertebrate assemblages. Overall, the loss of community diversity measured by the Shannon Index along the degradation gradient was observed. Some taxa were shown to be sensitive to water pollution, especially among Plecoptera, Trichoptera, Coleoptera and some Ephemeroptera, while others such as Simuliidae, Odonata and molluscs were tolerant to moderate levels of pollutants. The Chironomidae were the only group tolerant to a high level of pollutants and degradation.

The ‘natural’ vegetation of the Mexican Bajío: Archival documentation of a 16th-century Savanna environment

Neo-ecologists make assumptions about a ‘natural’ or potential vegetation when they argue whether a particular landscape is in secondary and degraded condition. Similarly, paleoecologists attempt to infer a three-dimensional biotic mosaic from a core taken in a low-lying wetland. Yet with millennia of human disturbance, climatic fluctuation, biotic response to long-term climatic trends or catastrophic ‘events’, and co-evolution between Holocene vegetation and human land-use, ‘natural ecosystems’ have not been in equilibrium. While past vegetation changes can be traced, efforts to reconstruct potential vegetation are probably unrealistic. This paper assembles 16th century landscape descriptions of the Bajio of Central Mexico from archival repositories, to characterise the landscape at the time of Spanish intrusion. Attention is focused on five major landscape elements: (1) Riparian woodlands of mesquite, bald cypress and willow, with reed stands; (2) Level, vertisolic plains, with a low-tree savanna (mesquite-acacia-grass); (3) Steeper piedmont plains with stony substrates, probably favoring xeric, thorn-bush associations; (4) Rough uplands with a mix of mesquite-acacia woodland, scrub oak, and thorn bush; and (5) Mountains dominated by live and deciduous oak woodlands. The biotic mosaic of the 16th century appears similar to that of the modern spontaneous vegetation in physiognomic terms, despite changes in structure. Areas of older indigenous settlement were affected by local vegetation disturbance, with partial deforestation near lakes Cuitzeo and Yuriria. While Spanish-Criollo intrusion (1540–1640) brought new, potentially destructive landuse methods, there is no evidence of additional landscape degradation in the Bajio until well into the 18th century. Dramatic changes in hydrology and riparian vegetation are quite recent. Archival documentation provides a complementary methodology to re-examine the interplay of edaphic variation, climate and cumulative land-use in understanding contemporary vegetation, and it can assist in converting proxy data into a three-dimensional landscape.

Woody colonization on unmanaged urban and ex-industrial sites

Summary Forty-six unmanaged urban and ex-industrial sites in the county of Avon, South Staffordshire and the West Midlands were visited in 1992/93 during a survey which aimed to relate site factors with natural colonization by trees and shrubs. The factors observed included: type and texture of substrate; the predominant type of vegetation; aspect; the presence of parents in the near vicinity of the site and the numbers and species of colonizing woody plants. The extent of woody colonization was very variable and despite an average stocking density of 1500 stems ha1, only 19 per cent of the land surveyed was colonized to an acceptable woodland standard. Woodland produced by natural colonization was species poor with an average of three per site; the most abundant species were ash, birch, goat willow and hawthorn, which made up 85 per cent of the colonization recorded. Although there was variation between species, the presence of the parent was usually the most important factor associated with colonization; when potential parent trees were visible from the site there was, on average, a 58 per cent probability of finding colonization of the corresponding species. In general, colonizing plants were positively associated with subsoil, small stony substrates such as gravel and ballast, and a weak grass sward. Conversely colonization was negatively associated with loam soils, sand, unfractured rock/concrete substrates, and sites with grazed sward or no vegetation.

Longitudinal zonation of the benthic invertebrate fauna in the river Glomma, Eastern Norway

Zonation studies of the benthic invertebrate fauna of stony substrates were made along a longitudinal gradient (600 km) in the Glomma river which drains 13% of Norway's land area (41767 km2). Wide differences in the faunal composition were found between the upper, middle and lower reaches of the river. Plecoptera were most abundant in the upper and Chironomidae and Trichoptera in the lower reaches. Ephemeroptera were abundant throughout the river. The faunal composition showed a dominance of shredders in the upper, grazers in the middle and collectors in the lower reaches. Some local effects of human influence were observed, but no general changes from the natural faunal composition and zonation seem to have taken place. The benthic data are in general agreement with the predictions of the River Continuum Concept (Vannote et al. 1980).

Evolutionary and Ecological Relationships Between Quail-Thrushes

Cladistic and phenetic clustering methods indicate two main groups of species in the quail-thrush genus Cinclosoma: a closely linked group composed of cinnamomeurn, alisteri, castaneothorax and marginatum, and a looser group containing punctatum, ajax and castanotum. The first cluster is an example of allopatric speciation and subspeciation within the deserts of Australia; the second provides an example of the derivation of a semi-arid form from a wet-country one. Members of the cinnamomeum group are allopatric except for parapatry between cinnamomeum and castaneothorax, these two forms hybridizing in some areas but not in others. No more than two taxa occur in the same geographical area and wherever there is overlap, one taxon is always castanotum which is partly sympatric with marginatum and cinnamomeum, marginally sympatric with punctatum and parapatric with alisteri. All quail-thrush taxa breed in the winter semester and dry-country populations also breed in the summer semester. Overlap in food between quail-thrushes is considerable but potential competitors generally segregate by habitat or substrate. Members of the cinnamomeum complex prefer stony substrates and where they overlap geographically with castanotum, the latter inhabits sandy substrates though elsewhere it may also frequent stony ground. The parapatric boundaries between cinnamomeum and castaneothorax and between castanotum and alisteri coincide with sharp changes in habitat. It is concluded that allopatry and parapatry in Cinclosoma is caused not only by competitive interactions but also by recency of speciation and subspeciation and by adaptation to different habitats, climates and substrates.