Local habitat characteristics determine butterfly diversity and community structure in a threatened Kihansi gorge forest,Southern Udzungwa Mountains,Tanzania

Background:Many species inhabiting Kihansi gorge ecosystem in Southern Udzungwa Mountains,Tanzania are threatened with extinction due to habitat loss caused by constructed hydropower plant that diverted over 90%the water off the Kihansi River.Understanding ecological correlates and structure of an animal community in perturbed ecosystems is an important way to enhancing species conservation particularly in this system,where several species are already threatened with extinction.This study assessed influences of local habitat characteristics on the butterfly abundance,species richness and diversity and examined how the butterfly community structures across three structurally heterogeneous habitats in the Kihansi gorge forest.Butterfly abundance data were collected using baited traps and measured environmental variables in the field,where trapping occurred.To understand the diversity and butterfly richness,these parameters were computed under Primer software.Non-metric multidimensional scaling and analysis of community similarity were used to analyse the butterfly community structure.Furthermore,the generalized linear models(GLM)were used to assess how the measured variables explained observed species diversity,abundance,and richness.Results:In total,72 species of butterfly in five families were recorded.Butterfly species diversity and richness did not vary across the habitat types or elevation gradient but showed strong correlation with some habitat characteristics.In addition,there was evidence of butterfly communities structuring into distinct groups that showed greater separation associated with the habitat characteristics they utilise.Furthermore,across the study area,butterfly species diversity increased significantly in high canopy and in trees with smaller DBH and at lower ground cover.Similarly,abundance significantly increased in the woodland and wooded grassland habitats,where there was high canopy and where tree density was high.Furthermore,butterfly species richness was strongly positively associated with high canopy cover and mostly increased in sites closer to water source.Conclusion:First,this study shows strong positive correlation between the habitat characteristics and butterfly species and community structure,suggesting strongly that maintaining habitat quality should be a priority in conserving the butterfly communities in Kihansi.Second,conservation of environmental disturbance indicator butterfly taxa which are also endemic and rare is worthy of concern under the ongoing human-induced threats in the area.It is appropriate time that the Tanzania government should declare the Kihansi gorge forest among existing protected areas to secure effective conservation of biological diversity in this threatened ecosystem.Third,the ants–butterfly symbionts and their links to the potential lichen depletion are still unclear,and thus future research should explore the trophic cascades of depleting habitat quality on the endemic and rare butterfly species in the Kihansi gorge.

Comparison of nominal and standardized catch per unit effort data in quantifying habitat suitability of skipjack tuna in the equatorial Pacific Ocean

In the western and central Pacific Ocean,upper strata waters exhibit highly dynamic oceanographic features under ENSO variability.This has been proved to be responsible for the dynamic change of both abundance and zonal distribution of skipjack tuna(Katsuwonus pelamis).Although causality has been suggested by researchers using physical-biological interaction models,cumulative evidence needs to be obtained and the tenability of assertion needs to be tested from an ecological habitat perspective,based on fisheries data.For purse seine fishery,the use of catch per unit effort(CPUE)as an indication of the abundance is confusing because of technical improvements over the whole exploitation history and unbalanced individual fishing characteristic of vessels.It is particularly interesting to discriminate between habitat characteristics in comparative scenarios of CPUE application.This study identified habitat traits based on a series of oceanographic factors from a global ocean reanalysis model.A comparison was conducted between two habitat models based on unprocessed purse seine CPUE and standardized CPUE considering fishing characteristics.The results suggest that standardized CPUE could model the regular zonal shift of habitat compatible with the observed fishing efforts transfer,and achieved better prediction capacity than unprocessed CPUE.Furthermore,the habitat of skipjack tuna was also characterized and linked with surface and subsurface thermal environment,ocean current,dissolved oxygen,biotic environment,and ENSO variability.The monthly-averaged habitat suitable index,derived from the optimal habitat model prediction,showed a significant linear relationship with the southern oscillation index,which suggested that El Ni?o episodes eventually provide more preferable habitat for skipjack tuna under ENSO variability.

Flexible nest site selection of the endangered Oriental Storks(Ciconia boyciana):Trade-off from adaptive strategies

Nest site selection is a vital component of bird reproduction success,and an adaptive behavior conducted to decrease nest predation risk with avoiding external disturbances.Understanding patterns of nest site selection can provide insights into how species adapt to changes in their habitat and has important conservation implications.In this study,we used microhabitat variables and multi-scale data with a field survey of nest occurrence to determine nest site selection patterns and adaptive strategies of the breeding Oriental Storks(Ciconia boyciana)in different nest areas.Results demonstrate that the nest site microhabitat characteristics of the breeding Oriental Storks significantly differed among the three nesting areas,and nest height was higher in the middle and lower Yangtze River floodplain than in the Northeast China and Bohai Bay nest areas.The food resources and intensity of human disturbance had the greatest effects on the nest site selection of the breeding Oriental Storks.The intensity of human disturbance was positively correlated with the nest height of the breeding Oriental Storks in Bohai Bay and the middle and lower Yangtze River floodplain;however,nest height decreased with the abundance of food resources in the Northeast China nest area.Our findings indicate that the nest site selection patterns of Oriental Storks showed flexible adaptive strategies.In safer environments,nests were lower and closer to food resources,which allows parent storks to invest more in the nestlings.However,in areas where human activity was intense,nests were higher to ensure the safety of their offspring.Some measures that could be taken to improve the breeding habitat of Oriental Storks include increasing the percentage of wetland areas in nesting areas to enhance food resources availability and setting artificial nests at suitable heights in potential nesting grounds to encourage nesting.Finally,the establishment of soft barriers around the nesting areas could increase the safety of nests.

Abiotic Sponge Ecology Conditions,Limski Kanal and Northern Adriatic Sea,Croatia

The Limski kanal, a semi-closed inlet (channel-like bay) located on the western coast of Istria (Croatia), is an extraordinary sponge habitat. Research on the marine ecosystem has been conducted there for more than 100 years. Today, 42 valid Porifera species are described. 139 species are listed for the area around Rovinj and 159 species for the northern Adriatic Sea. While several scientists described the sponge fauna, information on the abiotic situation or an explanation for the diversity differences is missing. This study interprets physicochemical and ecological parameters including depth profiles (temperature, salinity, pH-value, oxygen, water current velocity, photosynthetically active radiation [PAR], water transparency and nutrients). Their variances are linked with the distribution patterns of the prevailing sponge fauna. The channel is characterised as predominantly marine habitat. Although a shallow sediment barrier and a headland reduce the impact of the northern Adriatic Sea, differences between the channel and the open sea seem to be limited. Compared to the more homogenous water body of the Adriatic sampling locations, the channel shows variations and gradients of ecological parameters between different locations (e.g., due to freshwater influx: nutrients, temperature, oxygen content, salinity and water current velocity) – this offering habitat diversity. The sponge fauna changes along those ecological gradients. It is dominated by the photophilic species Aplysina aerophoba and Chondrilla nucula, but sciaphilic species such as Dysidea avara, Axinella polypoides and Aplysina cavernicola can be found, too. Some specialised species (e.g., Geodia cydonium, Tethya aurantium) even populate the muddy bottom of the channel.

Natural variation of physical-habitat conditions among least-disturbed streams of a neotropical river basin in Brazil

The determination of natural variation in physical habitat conditions and the establishment of least-disturbed reference standards is important for ecosystem conservation.Tropical regions hold most of the global freshwater diversity,nevertheless little is known about the natural conditions of their physical habitats.We calculated 255 physical habitat metrics for 31 stream sites in five protected areas of the Brazilian S~ao Francisco River basin to identify the most variable characteristics among tropical streams in least-disturbed areas.We performed principal components analyses(PCA)to find the most relevant metrics for ordination of streams in the following categories:water quality(2);substrate(7);fish shelter(6);riparian vegetation(9);and channel morphology(7).We used distance-based linear models(DISTLM)to test how much of the variation of these metrics could be explained by geographic position,average elevation,and average discharge of stream sites.The best statistically significant models explained 42%of substrate(33%geographic position;9%average elevation),26%of channel morphology(22%geographic position;4%average discharge),23%of water quality(14%geographic position;9%average discharge),17%of fish shelter(9%geographic position;8%average elevation),and 14%of riparian vegetation(7%geographic position;7%average elevation)variation.Thus,regional features(e.g.geology and climate)related to the geographic position are of greatest importance,followed by average elevation and discharge for determining physical habitat characteristics.Therefore,we suggest that reference sites should be set for tropical streams in the same regional landscape and with similar average elevation and discharge.

Habitat heterogeneity influences avian feeding guild composition in urban landscapes:evidence from Bhubaneswar,India

Background:Habitat heterogeneity clearly distinguished in terms of availability of food and habitat resources and landscape features(natural or human-modified)play a crucial role in the avian species composition and population structure.To examine this,a study was carried out in Bhubaneswar,India,to understand the ecological niche distinction in birds based on habitat heterogeneity.Regular sampling was conducted in 30 sampling sites covering six different habitat types in a predominantly urban landscape of Bhubaneswar for understanding the ecological niche in birds.The birds were classified into 11 types of foraging guilds.Results:The insectivorous guild had the highest bird species richness(181 species)and the omnivorous guild had the lowest(11 species).The piscivorous guild and wetland habitat had the strongest linkage,followed by the insectivorous guild and agricultural land.The frugivorous guild was significantly correlated with forest habitats(r=0.386,p<0.01)and park and garden habitats(r=0.281,p<0.01).This urban area hosted a higher number of bird species in certain habitat types,viz.,agricultural lands(52%,115 species)and forest patches(50%,111 species).Conclusion:The present study highlights the importance of agricultural lands,forest patches,parks and gardens,and wetlands inside the cityscape for supporting avifauna.It is therefore suggested that such habitats should be conserved inside an urban area to protect native avifauna.Thus,the city development plan must invariably include strategies for conserving the forest patches inside the urban area.Measures must be taken to restrain the degradation of agricultural lands and reduce their utilization for non-agricultural purposes,which will help in further reducing the bird population decline in the urban landscape.

Genetic diversity and differentiation follow secondary succession in a multi-species study on woody plants from subtropical China

Aims Species diversity and genetic diversity may be affected in parallel by similar environmental drivers.However,genetic diversity may also be affected independently by habitat characteristics.We aim at disentangling relationships between genetic diversity,species diversity and habitat characteristics of woody species in subtropical forest.Methods We studied 11 dominant tree and shrub species in 27 plots in Gutianshan,China,and assessed their genetic diversity(A_(r))and population differentiation(F′_(ST))with microsatellite markers.We tested if Ar and population specific F′_(ST) were correlated to local species diversity and plot characteristics.Multi-model inference and model averaging were used to determine the relative importance of each predictor.Additionally,we tested for isolation-by-distance(IBD)and isolation-by-elevation by regressing pairwise F′_(ST) against pairwise spatial and elevational distances.Important Findings Genetic diversity was not related to species diversity for any of the study species.Thus,our results do not support joint effects of habitat characteristics on these two levels of biodiversity.Instead,genetic diversity in two understory shrubs,Rhododendron simsii and Vaccinium carlesii,was affected by plot age with decreasing genetic diversity in successionally older plots.Population differentiation increased with plot age in R.simsii and Lithocarpus glaber.This shows that succession can reduce genetic diversity within,and increase genetic diversity between populations.Furthermore,we found four cases of IBD and two cases of isolation-by-elevation.The former indicates inefficient pollen and seed dispersal by animals whereas the latter might be due to phenological asynchronies.These patterns indicate that succession can affect genetic diversity without parallel effects on species diversity and that gene flow in a continuous subtropical forest can be restricted even at a local scale.