Local Habitat Variables Research Articles

Depopulation and Changes in Habitat Type in Rural Areas in Aragón (Spain)

Objective: The study aims to examine recent transformations in rural habitats undergoing depopulation in Aragón, Spain, between 2010 and 2018. It seeks to verify changes in habitat concentration patterns and identify the underlying factors. Theoretical Framework: Drawing upon theories of rural exodus and demographic shifts, the research employs the Colas Index (Colas, 1945) to analyze habitat types—dispersed or concentrated. It recognizes the influence of agricultural changes, service provision challenges, and territorial dynamics on rural settlement patterns (Escolano and de la Riva, 2003; Nuninger et al., 2021). Method: The investigation focuses on depopulated municipalities in Aragón, utilizing a comparative analysis of the Colas Index from 2010 to 2018. Administrative boundaries define the study's territorial units, enabling the quantification of habitat changes and an assessment of their direction. The analysis integrates demographic and settlement dynamics to understand habitat evolution. Results and Discussion: Findings indicate varied habitat transformation processes across municipalities, confirming the heterogeneity of the rural landscape (Pinilla and Sáez, 2017). While transformations are not universal, they challenge the traditional link between depopulation and habitat concentration. The Colas Index proves valuable for characterizing habitat dispersion levels, yet its limitations in concentrated areas are acknowledged. Methodological constraints related to administrative boundaries and the complexity of rural-urban continua are also discussed. Research Implications: This study contributes to a nuanced understanding of depopulation impacts on rural habitats, informing territorial planning and demographic policies. It underscores the need for tailored strategies that consider local habitat variability and the potential for revitalization efforts in select areas. Originality/Value: By highlighting the diversity of habitat transitions amidst depopulation, the research offers fresh insights into rural settlement dynamics. Its value lies in demonstrating that depopulation no longer universally leads to habitat concentration, thus updating the scholarly discourse on rural transformation in Spain.

Hydrological dynamics, wetland morphology and vegetation structure determine riparian arthropod communities in constructed wetlands

Wetland hydrological dynamics often dictate the composition of biological communities found in or near wetlands, either directly or through changes in vegetation composition. However, much remains unknown, particularly regarding how riparian arthropods respond to such dynamics. In this study, we used high-resolution hydrological data, along with presence of grazing livestock and shoreline vegetation height from 41 constructed wetlands in south-western Sweden to explore flood zone areas, flood frequencies, vegetation and grazing as drivers of the resident arthropod communities. The collected material consisted of 26,817 arthropods, where the dominant groups were Diptera (13,258 specimens), spiders (6,207) and Coleoptera (2,858), which were collected using SLAM (Sea Land and Air Malaise) trapping, along with pitfall trapping and vacuum sampling of riparian arthropods. We found group-specific responses to inundation frequencies, where wetlands with higher frequencies had lower abundances of some beetles and tipulids, and where wetlands with longer low-water table periods contained less trichopterans and heteropterans. In contrast, the size of flood zone areas only affected some wolf spider groups, that were more abundant in wetlands with intermediately sized flood zones. Shoreline vegetation height affected multiple groups, spiders, beetles and dipterans, but in different directions, whereas presence of grazing livestock had limited impact on abundances and community compositions. Given the variable responses to wetland hydrological and structural drivers, it seems that wetland arthropod communities would benefit from a high local wetland habitat variability, or wetlandscapes where individual wetlands have differing hydrological dynamics, morphology and vegetation.

Do highly anthropized hydrological conditions in marshes influence fish communities according to their life‐history strategies?

AbstractAlterations of natural hydrology in aquatic ecosystems are known to strongly impact the community composition of different taxa. Surprisingly, literature on the potential influence of hydrology on fish community composition is still very scarce in agricultural marshes, where canals represent one of the few remaining aquatic habitats. This study is aimed to address this research gap by monitoring fish communities in independent hydrological units differing in hydrology management over a 6 years period. We predicted variable fish responses to the hydrological context according to different life‐history strategies (opportunistic, equilibrium, or periodic species). Periodic and opportunistic species were the most frequently observed. Despite differences in hydrology between canals (but little variation over years), we found that hydrology explained only a very low proportion of variation in the composition of fish communities. In particular, the flooding duration of meadows in early spring did not influence the composition of fish communities, not even the abundance of periodic species expected to rely on such temporary habitats. Instead, fish communities were more influenced by local habitat variables (aquatic vegetation cover, turbidity, tree roots, and refuges under the canal banks). The hydrological management of most hydrological units for agricultural purposes (i.e., severe flood abatement in spring and shallow water depth in canals in summer) was found to be incompatible with conservation goals to promote more diverse fish communities between hydrological units. Therefore, we call for further investigations in similar habitats covering a larger range of hydrological conditions.

Synergistic effects of climate and salinity on radial growth of Excoecaria agallocha L. in the Sundarbans world heritage mangrove ecosystem

The Sundarbans World Heritage ecosystem provides valuable ecosystem goods and services to >7.5 million coastal people in South Asia. This sentinel mangrove ecosystem is threatened by historical anthropogenic disturbances, salinity intrusion and long-term environmental changes including sea level rise. Understanding which factors regulate mangroves’ growth is crucial for taking effective management decisions under global changes. However, a paucity of long-term mangrove tree growth data has limited our ability to quantify and predict the impacts of global changes on mangrove ecosystems. Using long-term growth data archived from the stem discs, this study, therefore, aims to understand how climatic and habitat variables influence radial growth dynamics in Excoecaria agallocha, a hyperdominant mangrove species in the Bangladesh Sundarbans. We find E. agallocha forms a distinct tree-ring boundary characterized by a narrow (2–4 cells wide) band of radially flattened fibres. The crossdatable tree-rings enabled us to develop two ecological zone-specific (low and high saline zone) chronologies (1972–2020) covering the entire salinity stress gradient present in the Sundarbans. Our analyses show: (I) radial growth rate in E. agallocha is significantly lower in the high saline zone, (II) monsoonal precipitation enhances radial growth, (III) large-scale climate drivers, such as sea surface temperature (SST) of the equatorial Pacific and the Indian Ocean, and the El Niño-Southern Oscillation (ENSO) influence tree growth through modifying the local precipitation in varying seasons, and (IV) local habitat variables, such as soil salinity and siltation have combined effects on radial growth of trees although soil salinity exhibits stronger negative effect. Our results highlight the importance of integrating both climate and local habitat variables with tree-ring data for a better understanding of tree growth dynamics under changing environment.

The impacts of hydropower on freshwater macroinvertebrate richness: A global meta-analysis.

Hydroelectric dams and their reservoirs have been suggested to affect freshwater biodiversity. Nevertheless, studies investigating the consequences of hydroelectric dams and reservoirs on macroinvertebrate richness have reached opposite conclusions. We performed a meta-analysis devised to elucidate the effects of hydropower, dams and reservoirs on macroinvertebrate richness while accounting for the potential role played by moderators such as biomes, impact types, study designs, sampling seasons and gears. We used a random/mixed-effects model, combined with robust variance estimation, to conduct the meta-analysis on 107 pairs of observations (i.e., impacted versus reference) extracted from 24 studies (more than one observation per study). Hydropower, dams and reservoirs did significantly impact (P = 0.04) macroinvertebrate richness in a clear, directional and statistically significant way, where macroinvertebrate richness in hydropower, dams and reservoirs impacted environments were significantly lower than in unimpacted environments. We also observed a large range of effect sizes, from very negative to very positive impacts of hydropower. We tried to account for the large variability in effect sizes using moderators, but none of the moderators included in the meta-analysis had statistically significant effects. This suggests that some other moderators (unavailable for the 24 studies) might be important (e.g., temperature, granulometry, wave disturbance and macrophytes) and that macroinvertebrate richness may be driven by local, smaller scale processes. As new studies become available, it would be interesting to keep enriching this meta-analysis, as well as collecting local habitat variables, to see if we could statistically strengthen and deepen the conclusions of this meta-analysis.

Long‐term minnow community trait shifts and metacommunity dynamics in a geomorphically unstable river

AbstractEcological disturbances may affect both habitat connectivity and heterogeneity, changing the dominant metacommunity processes affecting local communities. Altered fluvial sediment dynamics in rivers experiencing headcutting and accelerated erosion may foster morphologically unstable reaches in which supplies of habitat‐forming materials are spatially and temporally unpredictable. We hypothesise such environments will select for species with traits which promote dispersal or rapid resource use. We tested this hypothesis using historical and recent datasets from a biologically and functionally diverse taxonomical group, minnows (Leuciscidae and Cyprinidae) in the Bayou Pierre, Mississippi. Local communities decreased in both α and β‐diversity over time. Spatial autocorrelation of communities was consistently high through time, and more strongly related to regional community structure than local habitat variables in contemporary data. Communities shifted towards species with larger body sizes, less parental care, shorter age at maturity and higher fecundity. Communities also shifted towards more generalist species with lower potential trophic positions, and keystone species declined. Our data support the hypothesis of community‐level shifts towards species with dispersal trait syndromes and opportunistic resource utilisation. These shifts have led to a decrease in ecological complexity and overall homogenisation of minnow communities in the geomorphically evolving Bayou Pierre mainstem. The Bayou Pierre presents a unique window into ecological dynamics in a watershed characterised by altered sediment dynamics and sediment loss, in contrast to the large body of literature examining systems with increased sedimentation. These insights demonstrate the importance of studying the full range of fluvial sediment dynamics, including how broader processes of loss and transport may affect long‐term habitat stability, persistent trait syndromes and metacommunity dynamics.

Fish functional responses to local habitat variation in streams within multiple land uses areas in the Amazon

Abstract In this study, we assessed the effects of multiple land uses and local habitat variables on the composition of fish functional trophic groups (FTG’s) and on the ecomorphological traits of fish in Amazonian streams. We evaluated land use types and local habitat variables in 26 streams distributed within a land use gradient. Land use and habitat variables affected the composition of FTG’s, as evidenced by the increased abundance of diurnal channel drift feeders in areas with high dissolved oxygen and deeper thalweg. At the same time, diurnal surface pickers, as well as diggers, and ambush and stalker predators were more abundant in streams with higher canopy density. Only habitat variables affected the ecomorphological characteristics of the species. Fish with higher values of relative caudal peduncle length were positively associated with high canopy density, while fish with greater relative mouth width were negatively associated with the variables impact in the riparian zone and cover of fish shelter. The stream fish functional structure was mainly affected by the impacts caused to the local habitat resulting from different land uses. Thus, preserving forest remnants, as well as recovering degraded areas, is essential for the maintenance of aquatic biodiversity in the region.

Spatial and seasonal patterns of fish assemblages in mountain streams of the Ren River, southwest China.

The spatial–temporal patterns of fish assemblages in lotic systems can provide useful information in developing effective conservation measures. This study aimed to explore the spatial and seasonal changes in fish assemblages and their association with environmental factors in mountain streams of the Ren River, southwest China. Field investigations were conducted at 18 sites during the rainy and dry seasons in 2017. A total of 1,330 individuals, belonging to three orders, eight families, 19 genera, and 21 species, were collected. Analysis of similarities (ANOSIM) showed that the structure of fish assemblages varied significantly at the spatial scale, but not at the seasonal scale. In low‐order sites, fish assemblages were mainly dominated by cold‐water and rheophilic species (e.g., Rhynchocypris oxycephalus, Scaphesthes macrolepis, Metahomaloptera omeiensis, and Gnathopogon herzensteini), while those in high‐order sites were predominated by warm‐water and eurytopic or stagnophilic species (e.g., Squalidus argentatus, Hemiculter leucisculus, and Zacco platypus). Canonical correspondence analysis (CCA) showed that the fish assemblages were structured by a combination of large‐scale landscape factors (e.g., altitude and C‐link) and small‐scale habitat features (e.g., channel width, water temperature, and depth). Among these factors, landscape had the greatest influence on fish assemblages, while local habitat variables were less important or were only significant in certain seasons.

The co-occurrence of Ural Owls Strix uralensis and Northern Goshawks Accipiter gentilis differs between extensive and fragmented forests

ABSTRACT Capsule Territories of the nocturnal Ural Owl Strix uralensis and diurnal Northern Goshawk Accipiter gentilis were spatially associated in fragmented forest but not in extensive forest. Aims To test the hypotheses that (i) the patterns of distribution of Ural Owl and Northern Goshawk territories are different in extensive and fragmented forests and (ii) the distribution of their territories do not depend on local forest structure and habitat variables. Methods The territories of Northern Goshawks and Ural Owls were identified in forests in southern Poland. Spatial analysis was used to examine the co-occurrence patterns of the two species, and multivariate analysis to examine the impact of environmental cues on territory selection. Results Most habitat parameters were not significantly related to the presence of territories of either species. For Northern Goshawk there was a positive association with the occurrence of old-growth patches and a negative association with clear-cut areas and proximity to forest edge in fragmented forests; for Ural Owl there was a significant effect of wood type in extensive forest. None of the habitat parameters distinguished the territories of the two species, suggesting similarity in the habitats used. The territories of the two species were spatially associated in fragmented forests, suggesting some positive interspecific relationship. In contrast, the distributions of the two species were not significantly associated in extensive forest. Conclusions To explain the spatial co-occurrence between Northern Goshawks and Ural Owls we suggest: (i) Ural Owls can occupy unused Northern Goshawk nests in managed extensive forest where there is a deficiency of large tree cavities; (ii) restricted availability of habitat in fragmented forests forces both species to nest in close proximity, and/or (iii) Ural Owls use social information from Northern Goshawks about habitat quality when selecting territories in some landscapes.

Fish communities and associated habitat variables in the upper Subansiri River of Arunachal Pradesh, eastern Himalaya, India

Ecological information on the rivers of eastern Himalaya, specifically the state of Arunachal Pradesh is not studied well. The present study describes fish assemblage patterns and deriving relationships between local habitat variables in the upper reaches of Subansiri River, Arunachal Pradesh. This study was carried out during October to November 2014 and February to March 2015. A total of 26 fish species belonging to eight families were recorded, in which eight species are endemic to the eastern Himalayan region. Fish species richness varied from two to 18 species in the upper reaches of Subansiri River and high species diversity was recorded in Sigin Stream (H’=2.76). Based on the seven habitat variables (water velocity, depth, channel width, percentage of substrate composition, percentage of riparian vegetation, altitude, and water temperature) then streams were categorized into lower-order and higher-order streams using principal component analysis (PCA). The site-wise fish abundance data along with habitat variable information was then subjected to the canonical correspondence analysis (CCA) for testing the association of habitat variables on fish abundance. The CCA results revealed that the abundance of large-size barbs, Neolissochilus hexagonolepis, N. nigrovittatus, Schizothorax progastus, and S. richardsonii were strongly associated with high altitude, water velocity, rich dissolved oxygen, and good riparian vegetation. On the other hand, Channa gachua, Botia rostrata, Danio rerio, Devario aequipinnatus, and Garra nasuta showed strong association with warm water streams with more conductivity.

Differences in Response of Butterfly Diversity and Species Composition in Urban Parks to Land Cover and Local Habitat Variables

Background and Objectives: As urbanisation is a significant global trend, there is a profound need for biodiversity protection in urban ecosystems. Moreover, the potential of urban green space to support urban biodiversity should be appreciated. Butterflies are environmental indicators that are sensitive to urbanisation. Therefore, it is important to identify butterfly distribution patterns and the factors influencing butterfly diversity and species composition in urban parks within cities. Research Highlights: To our knowledge, ours is the first study evaluating the effects of both land cover and local habitat features on butterfly species composition in urban parks of Beijing, China. Materials and Methods: In this study, we surveyed butterfly richness and abundance in 28 urban parks in Beijing, China. The parks differed in age and location in the urban area. Meanwhile, we investigated the green space in the surroundings of the parks at multi-spatial scales at the landscape level. We also investigated local park characteristics including the age of the park (Age), perimeter/area ratio of the park (SQPRA), area of the park (ha) (Area), green space cover within the park (Greenp), nectar plant species richness (Necpl), abundance of flowering nectar plants (Necabu) and overall plant species richness (Pl). Generalised linear models (GLMs) and redundancy discriminant analysis (RDA) were applied to relate butterfly diversity and butterfly species composition to environmental variables, respectively. Results: We recorded 3617 individuals belonging to 26 species from July to September in 2019. Parks on the city fringe had significantly higher butterfly diversity. Butterfly species richness was mostly related to total plant richness. The abundance of flowering nectar plants was closely linked to butterfly abundance. Land cover had little impact on butterfly diversity and community structure in urban parks. Conclusions: Once a park has sufficient plants and nectar resources, it becomes a useful haven for urban butterflies, regardless of the surrounding land cover. Well-planned urban parks focused on local habitat quality support butterfly conservation.

Determinants of Wetland- Bird Community Composition in Agricultural Marshes of the Northern Prairie and Parkland Region

Wetland losses in the Northern Prairie and Parkland Region are largely attributed to agriculture. Since land use is known to influence bird habitat selection, bird community composition is likely sensitive to the extent of neighboring agricultural activity. We determined local and landscape habitat variables predictive of wetland-dependent avian assemblage occurrence in southern Alberta. We: 1) identified distinct bird assemblages with a cluster analysis, 2) identified species indicative of these assemblages using an indicator species analysis, and 3) predicted bird assemblage occurrence in wetlands using a classification and regression tree. Wetland-dependent birds formed distinct avian assemblages that were primarily differentiated by region and local-level habitat characteristics like wetland size, depth, or vegetation cover. Generally, however, wetland-dependent bird assemblages were surprisingly insensitive to surrounding landscape composition. The extent of agricultural activity in the surrounding landscape was weakly predictive of avian assemblages in wetlands in the Grassland Natural Region, with edge-nesting birds being excluded from wetlands with >42% agricultural land cover in the surrounding landscape.

Bacterial dispersal and drift drive microbiome diversity patterns within a population of feral hindgut fermenters.

Studies of microbiome variation in wildlife often emphasize host physiology and diet as proximate selective pressures acting on host-associated microbiota. In contrast, microbial dispersal and ecological drift are more rarely considered. Using amplicon sequencing, we characterized the bacterial microbiome of adult female (n=86) Sable Island horses (Nova Scotia, Canada) as part of a detailed individual-based study of this feral population. Using data on sampling date, horse location, age, parental status, and local habitat variables, we contrasted the ability of spatiotemporal, life history, and environmental factors to explain microbiome diversity among Sable Island horses. We extended inferences made from these analyses with both phylogeny-informed and phylogeny-independent null modelling approaches to identify deviations from stochastic expectations. Phylogeny-informed diversity measures were correlated with spatial and local habitat variables, but null modelling results suggested that heterogeneity in ecological drift, rather than differential selective pressures acting on the microbiome, was responsible for these correlations. Conversely, phylogeny-independent diversity measures were best explained by host spatial and social structure, suggesting that taxonomic composition of the microbiome was shaped most strongly by bacterial dispersal. Parental status was important but correlated with measures of β-dispersion rather than β-diversity (mares without foals had lower alpha diversity and more variable microbiomes than mares with foals). Our results suggest that between host microbiome variation within the Sable Island horse population is driven more strongly by bacterial dispersal and ecological drift than by differential selective pressures. These results emphasize the need to consider alternative ecological processes in the study of microbiomes.

Unravelling patterns of taxonomic and functional diversity of Amazon stream fish

Environmental filtering and dispersal limitation are essential processes affecting the variability of ecological communities. However, their relative contributions are highly debated and remain largely unknown in several systems, such as the hyperdiverse Amazon Basin. We determined the relative role of local, catchment, spatial, and biogeographical variables on the taxonomic and functional alpha and beta diversity of stream fish. We sampled 54 streams across six river basins in the Amazon. For each stream, we obtained 35 local habitat variables and 11 climate-catchment variables. Watercourse distances and basin identity were converted into spatial and biogeographical variables, respectively. We found that taxonomic alpha diversity responds both to spatial and local predictors, whereas its functional counterpart was mainly associated with local variables. Biogeography was the main factor structuring taxonomic and functional beta diversity, with a secondary contribution of catchment and local variables. Locally, substrate type and isolation determined the number and relative abundance of species and traits. The shared variation between biogeographical and environmental variables, especially altitude and slope, were strongly associated with beta diversity patterns, indicating a joint role of habitat filtering and dispersal limitation. Our results show the need to include both spatial and environmental variables in studies of stream communities at large spatial scales, as they are related to distinct processes that regulate community structure. We also encourage future studies to account for the responses of multiple facets of biodiversity to different drivers, as they provide essential and complementary information for community ecology and biogeography.

Wintry habitat selection of the Zapallaren tree iguana (Liolaemus zapallarensis, Müller & Hellmich, 1933) and its abundance in Changa beach, Coquimbo, northern Chile

Urban development modifies the habitat of reptiles where we expect, the individuals to select available sites with the quality necessary for their permanence. The aim of this study was to determine the variables that favored the habitat selection and abundance of The Zapallaren Tree Iguana Liolaemus zapallarensis, an endemic species of Chile, during a winter season in Changa beach, Coquimbo, in northern Chile. Between June and September 2017, we made 30 random visits to 18 plots of 900 m2 each. We estimated a resource selection probability function for presence-absence and abundance data using local habitat (e.g. slope, distance from the protection wall to the sea at low tide, interior height of the wall, mean height of the vegetation, rocky surface, and vegetal surface) and climatic variables (temperature, atmospheric pressure, direction and wind speed, solar radiation, and mean cloudiness) as predictors. Vegetation cover was the most important habitat variable explaining the presence of L. zapallarensis. In addition, increase in cloudiness and wind speed decreased the probability of selection. Manly’s selectivity measure varied according to the established home ranges and the availability ratios within them. Finally, increase in cloudiness and wind speed decreased the abundance. Overall, our results show that the characteristics related to habitat and local climate influences the resource selection that favors the survival of reptiles. This work shows that beach sectors in urban contexts under anthropic pressure have important available resources that favor the presence and abundance of reptiles.

The effect of hedgerow density on habitat quality distorts species-area relationships and the analysis of extinction debts in hedgerows

ContextHedgerows are highly important for maintaining the biodiversity in deforested landscapes. Especially for habitat specialists such as several forest plants they can provide important refuge habitats.ObjectivesThis study aims to examine whether there is an extinction debt for forest plants in hedgerows.MethodsIn a study area in Northern Germany that had lost 47% of the hedgerow network over the past 120 years, hedgerows were mapped for the presence of forest vascular plants. In a multi-model approach, we compared the explanatory power of present and historical landscape variables and habitat quality on diversity patterns.ResultsThe change in landscape configuration had no effect on the species richness of forest plants in hedgerows, i.e. there was no sign of an extinction debt. The best explanatory variable was the hedgerow width with more species found in wider hedgerows. This demonstrates the importance of including local habitat variables in the study of extinction debt. For ancient woodland indicator species models including both the landscape configuration and habitat variables were superior to simple models. The best models included the historical distance to the nearest forest, suggesting an extinction debt. Counterintuitively, a high density of hedgerows had a negative influence on species richness, most likely because hedgerows are narrower in areas with higher densities due to land-saving measures by farmers. There was also a negative correlation between hedgerow density and the hedgerow proximity to forests.ConclusionsThe effects of important covariates may obscure species-area relationships and undermine extinction debt analyses.

Living on the edge: Forest cover threshold effect on endangered maned sloth occurrence in Atlantic Forest

Habitat loss and the isolation of remaining habitats are undoubtedly the two greatest threats to biodiversity conservation, especially for the maned sloth, due to its ecological restrictions. In this study, we identified a critical threshold of forest cover for maned sloth occurrence and explored the effects of other local and landscape variables. We sampled 68 sites, where we searched for the maned sloth and collected local habitat variables. We calculated the percentage of forest cover and open areas, assessing the appropriated scale through model selection. We used occupancy models and model selection methods to identify the threshold and assess occupancy and detection probabilities. The occupancy probability of the maned sloth is 0.97, but it decreases abruptly at 35% of forest cover, reaching zero in areas with less than 20% of forest cover. The two landscape variables are the most important predictors of sloth occupancy, based on the cumulative weight of evidence, were: Forest cover (78%) and Open areas cover (46%); the latter influencing negatively maned sloth occupancy. This is the first attempt to identify the habitat requirements of the threatened maned sloth in a fragmented area using landscape and local variables. Our results imply that conservation of maned sloth will benefit from an increase in the amount of native forest at the landscape scale. Given difficulties in the creation of new public protected areas, this improvement could be achieved via the recovery of areas located in private properties that are protected by the Brazilian Forest Code.

Does catchment geodiversity foster stream biodiversity?

ContextOne approach to maintain the resilience of biotic communities is to protect the variability of abiotic characteristics of Earth’s surface, i.e. geodiversity. In terrestrial environments, the relationship between geodiversity and biodiversity is well recognized. In streams, the abiotic properties of upstream catchments influence stream communities, but the relationships between catchment geodiversity and aquatic biodiversity have not been previously tested.ObjectivesThe aim was to compare the effects of local environmental and catchment variables on stream biodiversity. We specifically explored the usefulness of catchment geodiversity in explaining the species richness on stream macroinvertebrate, diatom and bacterial communities.MethodsWe used 3 geodiversity variables, 2 land use variables and 4 local habitat variables to examine species richness variation across 88 stream sites in western Finland. We used boosted regression trees to explore the effects of geodiversity and other variables on biodiversity.ResultsWe detected a clear effect of catchment geodiversity on species richness, although the traditional local habitat and land use variables were the strongest predictors. Especially soil-type richness appeared as an important factor for species richness. While variables related to stream size were the most important for macroinvertebrate richness and partly for bacterial richness, the importance of water chemistry and land use for diatom richness was notable.ConclusionsIn addition to traditional environmental variables, geodiversity may affect species richness variation in streams, for example through changes in water chemistry. Geodiversity information could be used as a proxy for predicting stream species richness and offers a supplementary tool for conservation efforts.

Examining the influence of human stressors on benthic algae, macroinvertebrate, and fish assemblages in Mediterranean streams of Chile

Changes in land-uses and cover are strong drivers of stream degradation worldwide. In Mediterranean ecoregions, land conversion from forest with native species to tree plantations, agricultural, and urban areas have drastically increased in recent years. Here, we examined the influence of land-use types on water quality (physical and chemical variables) and biota (benthic algae, macroinvertebrates, and fishes). We conducted field surveys between December–March 2016 (dry season) in 24 sites located across four land-use types including native vegetation (NV), tree plantation (TP), agriculture (Ag), and urban (Ur) within the Chilean Mediterranean ecoregion. We calculated metrics and multivariate statistics to assess correlations between biological and environmental variables. Significant differences between land-uses were found for environmental/physicochemical variables and the three biotic groups (i.e., benthic algae, macroinvertebrates, and fishes). We found higher chlorophyll-a biomass for TP, Ag, and Ur compared to NV streams. The macroinvertebrate diversity of sensitive taxa (i.e., Ephemeroptera, Plecoptera, and Trichoptera) and water quality were lower in land draining streams with human uses, other than NV, with the most evident impact found in Ag and Ur streams. NV and TP streams had a lower Diptera density and lower percentage of non-insect taxa. Fish richness and diversity were not affected by land-use. However, cold-water fishes (both native and introduced) were closely associated with NV and TP streams whereas warm-water fishes (mostly introduced) were closely associated with Ag and Ur streams. Multivariate analysis revealed that both local habitat and catchment-scale variables influenced each biological assemblage. Our findings suggest that benthic algae, macroinvertebrates, and fish populations are good indicators of human land-use disturbances, with Ag and Ur areas being the most detrimental for freshwater biota.

Cyclical climate oscillation alters species statistical relationships with local habitat

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 614:159-171 (2019) - DOI: https://doi.org/10.3354/meps12890 Cyclical climate oscillation alters species statistical relationships with local habitat Sarah M. Roberts1,*, Andre M. Boustany2, Patrick N. Halpin1, Ryan R. Rykaczewski3 1Marine Geospatial Ecology Lab, Nicholas School of the Environment and Earth Sciences, Duke University, Durham, NC 27708, USA 2Monterey Bay Aquarium, 886 Cannery Row, Monterey, CA 93940, USA 3Marine Science Program, University of South Carolina, Columbia, SC 29208, USA *Corresponding author: sarah.m.roberts@duke.edu ABSTRACT: As anthropogenic climate change increases the temperatures of the world’s oceans, the survival rates, spatial distributions, and phenology of marine species are affected. Additionally, cyclical climate oscillations, such as the North Atlantic Oscillation (NAO), influence species presences throughout the Atlantic Basin. We evaluate the potential effects of local habitat variability on the nearshore presence of 7 commercial fish species along the South Atlantic Bight. Employing random forest models, we assess the relationships between historical observed presence and bottom temperature (BT), salinity, benthic habitat structure, and the NAO. Our results suggest that for some species, the influence of BT on species nearshore presence depends on the phase of the NAO. Thus, the statistical responses of some species to changing ocean temperatures will largely depend on the phase of the NAO. KEY WORDS: Climate change · Climate variation · North Atlantic Oscillation · Species distribution · Species-environment relationships Full text in pdf format Supplementary material PreviousNextCite this article as: Roberts SM, Boustany AM, Halpin PN, Rykaczewski RR (2019) Cyclical climate oscillation alters species statistical relationships with local habitat. Mar Ecol Prog Ser 614:159-171. https://doi.org/10.3354/meps12890 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 614. Online publication date: April 04, 2019 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2019 Inter-Research.