Diversity, Volume 11, Issue 3 (March 2019) – 19 articles

Few reports have been published on detection distances of bat calls because the evaluation of detection distance is complicated. Several of the approaches used to measure detection distances are based on the researcher’s experience and judgment. More recently, multiple microphones have been used to model flight path. In this study, the validity of a low-cost and simple detectability metric was tested. We hypothesize that the duration of an echolocating-bat-pass within the area of an ultrasonic bat detector is correlated with the distance of detection. Two independent datasets from a large-scale acoustic bat survey—a total of 25,786 bat-passes from 20 taxa (18 species and two genera)—were measured. We found a strong relationship between these measures of bat-pass duration and published detection distances. The advantages of bat-pass duration measures are that, for each study, experimenters easily produce their own proxy for the distance of detection. This indirect measure of the distance of detection could be mobilized to monitor the loss in microphone sensitivity used to monitor long-term population trends. Finally, the possibility of producing an index for distance of detection provides a weight for each bat species’ activity when they are aggregated to produce a bat community metric, such as the widely used “total activity”. Full article

Many coral reef systems are shelf-based and consist of reefs that are arranged in rows parallel to the coastline. They usually show an increase in species richness in the offshore direction, coinciding with decreasing terrigenous impact and a deeper seafloor. These two conditions usually concur, which makes it less easy to distinguish how each of them influences coral diversity separately. Since reefs off Jakarta (in the Thousand Islands archipelago) are arranged in an 80 km long string perpendicular to the coastline in south-to-north direction, with a maximum shelf depth halfway along (instead of at the end of) the string, this archipelago is very suitable for studies on inshore–offshore gradients. In the present study, mushroom corals (Fungiidae; n = 31) were used to examine diversity patterns on 38 reef sites along such a gradient, involving species richness over their entire depth range from reef flat to reef base (2–30 m) and separately at shallow depths (2–6 m). Total species diversity was highest in the central part of the archipelago, with unique species occurring in deep habitats. Diversity at shallow depths was only slightly higher here than at reefs located more nearshore and offshore, which both had less clear water. Therefore, shelf depth and distance from the mainland can be considered separate determinants of coral diversity off Jakarta. Full article

Climate change and the anthropic emission of pollutants are likely to have an accelerated impact in high-elevation mountain areas. This phenomenon could have negative consequences on alpine habitats and for species of conservation in relative proximity to dense human populations. This premise implies that the crucial task is in the early detection of warning signals of ecological changes. In alpine landscapes, high-elevation forests provide a unique environment for taking full advantage of epiphytic lichens as sensitive indicators of climate change and air pollution. This literature review is intended to provide a starting point for developing practical biomonitoring tools that elucidate the potential of hair-lichens, associated with high-elevation forests, as ecological indicators of global change in the European Alps. We found support for the practical use of hair-lichens to detect the impact of climate change and nitrogen pollution in high-elevation forest habitats. The use of these organisms as ecological indicators presents an opportunity to expand monitoring activities and develop predictive tools that support decisions on how to mitigate the effects of global change in the Alps. Full article

Scleractinian corals often exhibit high levels of morphological plasticity, which is potentially important in enabling individual species to occupy benthic spaces across a wide range of environmental gradients. This study tested for differences in the three-dimensional (3D) geometry of three branching corals, Acropora nasuta, Pocillopora spp. and Stylophora pistillata among inner-, mid- and outer-shelf reefs in the central Great Barrier Reef, Australia. Important attributes of coral morphology (e.g., surface area to volume ratio) were expected to vary linearly across the shelf in accordance with marked gradients in environmental conditions, but instead, we detected non-linear trends in the colony structure of A. nasuta and Pocillopora spp. The surface area to volume ratio of both A. nasuta and Pocillopora spp. was highest at mid-shelf locations, (reflecting higher colony complexity) and was significantly lower at both inner-shelf and outer-shelf reefs. The branching structure of these corals was also far more tightly packed at inner-shelf and outer-shelf reefs, compared to mid-shelf reefs. Apparent declines in complexity and inter-branch spacing at inner and outer-shelf reefs (compared to conspecifics from mid-shelf reefs) may reflect changes driven by gradients of sedimentation and hydrodynamics. The generality and explanations of observed patterns warrant further investigation, which is very feasible using the 3D-photogrammetry techniques used in this study. Full article

Lichen biomonitoring programs focus on temporal variations in epiphytic lichen communities in relation to the effects of atmospheric pollution. As repeated surveys are planned at medium to long term intervals, the alternation of different operators is often possible. This involves the need to consider the effect of non-sampling errors (e.g., observer errors). Here we relate the trends of lichen communities in repeated surveys with the contribution of different teams of specialists involved in sampling. For this reason, lichen diversity data collected in Italy within several ongoing biomonitoring programs have been considered. The variations of components of gamma diversity between the surveys have been related to the composition of the teams of operators. As a major result, the composition of the teams significantly affected data comparability: Similarity (S), Species Replacement (R), and Richness Difference (D) showed significant differences between “same” and “partially” versus “different” teams, with characteristics trends over time. The results suggest a more careful interpretation of temporal variations in biomonitoring studies. Full article

Lichens have been used as biomonitors for multiple purposes. They are well-known as air pollution indicators around urban and industrial centers. More recently, several attempts have been made to use lichens as monitors of climate change especially in alpine and polar regions. In this paper, we review the value of saxicolous lichens for monitoring environmental changes in Antarctic regions. The pristine Antarctica offers a unique opportunity to study the effects of climate change along a latitudinal gradient that extends between 62° and 87° S. Both lichen species diversity and thallus growth rate seem to show significant correlations to mean annual temperature for gradients across the continent as well as to short time climate oscillation in the Antarctic Peninsula. Competition interactions appear to be small so that individual thalli develop in balance with environmental conditions and, as a result, can indicate the trends in productivity for discrete time intervals over long periods of time. Full article

Long-term or cumulative diversity is the biodiversity that accumulates at a site over many generations of community members. Cumulative diversity is likely important to the intrinsic and functional value of ecosystems given the legacies left behind by many species. While its components—average short-term diversity (alpha) and temporal turnover (beta)—have been extensively studied, cumulative diversity itself has not. We therefore examined the environmental and community drivers of cumulative diversity with a novel hierarchical diversity partition. This partition breaks cumulative diversity into short-term, turnover, richness, and evenness components. We applied this framework to 49 tropical rock pool communities, censused over tens to hundreds of organism generations. Results uncovered two environmental regimes that differentially impacted the richness and evenness components of cumulative diversity: Occasional drying events mainly limited richness and reset communities, while less severe physicochemical variations reduced the evenness of communities. These causal pathways amount to differential controls on cumulative diversity; controls that can oppose each other to buffer diversity against change as well as create unexpected trade-offs for managers. We conclude that maintaining diversity at longer timescales requires new analytical tools and an expanded view that can account for its complexity. Full article

Head-starting is a conservation strategy that entails releasing captive-reared animals into nature at sizes large enough to better resist post-release predation. However, efforts to maximize growth in captivity may jeopardize development of beneficial behaviors. Environmental enrichment can encourage natural behaviors before release but potentially comes with a tradeoff of reduced growth in complex enclosures. We compared growth and behavior of enriched and unenriched captive-born juvenile box turtles (Terrapene carolina). Enriched turtles grew slower than unenriched turtles during the first eight months in captivity, although growth rates did not differ between treatments from 9–20 months old. After five months post-hatching, unenriched turtles became and remained larger overall than enriched turtles. During two foraging tasks, unenriched turtles consumed more novel prey than enriched turtles. In a predator recognition test, eight-month-old enriched turtles avoided raccoon (Procyon lotor) urine more than unenriched turtles of the same age, but this difference was not apparent one year later. The odds of turtles emerging from a shelter did not differ between treatments regardless of age. Although our results suggest turtles raised in unenriched environments initially grew faster and obtained larger overall sizes than those in enriched conditions, tradeoffs with ecologically-relevant behaviors were either absent or conditional. Full article

Ecosystem engineers can modulate harsh abiotic conditions, thus creating habitat for species that cannot withstand the local environment. In this study, we investigated if vacant boreholes created by the rock-boring bivalve Petricola dactylus increase species richness in the low intertidal zone of a Patagonian rocky shore characterized by intense hydrodynamic forcing and sediment scour. Invertebrate species richness was three times higher in engineered than unengineered habitats (i.e., with and without Petricola boreholes, respectively) and the increase in species richness was area-independent. The most prevalent species in unengineered areas showed strong adhesion mechanisms, whereas infaunal and vagile species were mostly restricted to boreholes. The positive influence of engineered microhabitats on species richness can largely be attributed to amelioration of physical conditions, particularly a reduction in hydrodynamic forces and sediment trapping/stabilization within boreholes. We conclude that vacant boreholes are essential microhabitats for the maintenance of biodiversity within the otherwise inhospitable low intertidal zone. Full article

Changes in coral reef health and status are commonly reported using hard coral cover, however such changes may also lead to substantial shifts in coral community composition. Here we assess the extent to which coral communities departed from their pre-disturbance composition following disturbance (disassembly), and reassembled during recovery (reassembly) along an environmental gradient across the continental shelf on Australia’s Great Barrier Reef. We show that for similar differences in coral cover, both disassembly and reassembly were greater on inshore reefs than mid- or outer-shelf reefs. This pattern was mostly explained by spatial variation in the pre-disturbance community composition, of which 28% was associated with chronic stressors related to water quality (e.g., light attenuation, concentrations of suspended sediments and chlorophyll). Tropical cyclones exacerbated the magnitude of community disassembly, but did not vary significantly among shelf positions. On the outer shelf, the main indicator taxa (tabulate Acropora) were mostly responsible for community dissimilarity, whereas contribution to dissimilarity was distributed across many taxa on the inner shelf. Our results highlight that community dynamics are not well captured by aggregated indices such as coral cover alone, and that the response of ecological communities to disturbance depends on their composition and exposure to chronic stressors. Full article

Lake Faro, in the North-Eastern corner of Sicily (Italy), shows the typical stratification of a meromictic tempered basin, with a clear identification of the mixolimnion and the monimolimnion, separated by an interfacial chemocline. In this study, an annual-scaled study on the space-time distribution of the microbial communities in water samples of Lake Faro was performed by both ARISA (Amplified Ribosomal Intergenic Spacer Analysis) and CARD-FISH (Catalyzed Reporter Deposition-Fluorescence In Situ Hybridization) approaches. A correlation between microbial parameters and both environmental variables (i.e., temperature, pH, dissolved oxygen, redox potential, salinity, chlorophyll-a) and mixing conditions was highlighted, with an evident seasonal variability. The most significative differences were detected by ARISA between the mixolimnion and the monimolimnion, and between Spring and Autumn, by considering layer and season as a factor, respectively. Full article

Epiphytic (tree inhabiting) lichens, well-known biomonitors of atmospheric pollution, have a great potential for being used in environmental forensics. Monitoring changes in biodiversity is a useful method for evaluating the quality of an ecosystem. Lichen species occurring within an area show measurable responses to environmental changes, and lichen biodiversity counts can be taken as reliable estimates of environmental quality, with high values corresponding to unpolluted or low polluted conditions and low values to polluted ones. Lichen diversity studies may be very useful in the framework of environmental forensics, since they may highlight the biological effects of pollutants and constitute the base for epidemiological studies. It is thus of paramount importance that great care is taken in the interpretation of the results, especially in the context of a rapidly changing environment and facing global change scenarios. For this reason, it seems advisable to produce several zonal maps, each based on different species groups, and each interpreted in a different way. This exercise could also be a valid support in the framework of a sensitivity analysis, to support or reject the primary results. In addition, a clear and formal expression of the overall uncertainty of the outputs is absolutely necessary. Full article

Common buzzard is the most abundant bird of prey in Europe, and its population has undergone serious changes. In this study, we focused on a population in Central Poland (study area 105 km², forests around 24 km², seven forest complexes) to analyze how certain environmental factors influenced population abundance, breeding parameters, and diet composition. The study was undertaken from 2011 to 2018, and the results were compared with data from two study periods (1982–1992; 2001–2003). Current population density was 3.5 pairs/10 km² of total area and 14.3 pairs/10 km² of forested area, it was negatively correlated to the abundance of northern goshawk, and it grew in the last few decades. Mammals were dominant prey (72.6% prey items, 38.6% of biomass), but their share in diet changed following rodent availability. A decrease in the share of voles was recorded, reflecting drop in their abundance and dampening of abundance cycles. Breeding parameters were similar to those in the past, and the number of offspring depended on small rodent availability. Buzzards adapted to changes in the stand structure, i.e., when share of Scots pine decreased, they chose it as their nesting tree less frequently. All this showed that buzzard is a very adaptable species. Full article

Global positioning system (GPS) telemetry units are now small enough to be deployed on terrestrial and semi-aquatic turtles. Many of these GPS units use snapshot technology which collects raw satellite and timestamp data during brief periods of data recording to minimize size. We evaluated locations from snapshot GPS units in stationary tests and on wood turtles (Glyptemys insculpta) in northeastern Minnesota. Stationary GPS units were placed in wood turtle habitat to evaluate location accuracy, fix success rate, and directional bias. The GPS fix success rate and accuracy were reduced in closed canopy conditions and when the stationary GPS unit was placed under a log to simulate wood turtle hiding behavior. We removed GPS location outliers and used a moving average calculation to reduce mean location error in stationary tests from 27 m (SD = 38) to 10 m (SD = 8). We then deployed GPS units and temperature loggers on wood turtles and collected 122,657 GPS locations and 242,781 temperature readings from 26 turtles from May to September 2015 and 2016. Location outliers accounted for 12% of locations when the GPS receiver was on a turtle. We classified each wood turtle location based on the GPS location and by comparing temperature profiles from river, sun, and shaded locations to the temperature logger on the turtle. We estimated that wood turtles were on land 68% (SD = 12) of the time from May to September. The fix success rate for land locations was 38% (SD = 9), indicating that wood turtles often use habitats with obstructed views of the sky. Mean net daily movement was 55 m (SD = 192). Our results demonstrate that snapshot GPS units and temperature loggers provide fine-scale GPS data useful in describing spatial ecology and habitat use of semi-aquatic turtles. Full article

Planktivorous damselfishes (Pomacentridae) are diverse and abundant on the Great Barrier Reef (GBR), are important prey for commercially harvested coral trout (Plectropomus spp.) and their feeding mode plays a central role in transferring energy from the plankton to the reef. However, little is known about their distribution patterns throughout the GBR and how those patterns are influenced by predators and habitat despite increasing pressures on both. Here we quantify the distribution and abundance of GBR planktivorous damselfishes, then examine the role of coral trout and habitat in shaping their assemblages. The assemblage structure of planktivorous damselfishes varied across the continental shelf, yet their total abundances varied sub-regionally, dependent on differences in coral habitat. Latitudinal patterns were relatively weak. Damselfish assemblages generally retained characteristics of their sub-regional setting over 20 years and assemblage degradation was only associated with major coral losses. Damselfish numbers were not negatively influenced by top-down control from coral trout. Instead, numbers of coral trout and damselfishes were both positively associated with coral habitat and each other. Our findings suggest that a complexity of factors and interactions shape reef fish assemblages and reinforce the fundamental importance of coral as the foundation of healthy reef communities. Full article

(1) Background: Neotropical montane forests represent one of the most diverse world ecosystems; however, they are also among the most threatened ones mostly due to deforestation. Our main goal is to classify and clarify the forest types based on the changes in basal area (BA), tree density, and species composition of montane forests in Southern Ecuador, and to determine the influence of critical environmental and geomorphological factors. (2) Methods: One hundred thirty-two temporary plots of 400 m² were installed in homogeneous and well-conserved forest stands. We identified and measured all trees >10 cm diameter breast height (DBH). We modeled species diversity (Fisher’s alpha) change in relation to climatic, altitudinal, and geomorphological gradients using GLM and Kruskall-Wallis analyses. The change in composition was determined using cluster analyses (BIOENV analysis followed by a LINKTREE procedure). Non-metric multidimensional scaling (NMDS) was used to analyze changes across climatic and geomorphological gradients. Finally, we used a SIMPER analysis to identify the species that contributed most to the floristic dissimilarity among the identified altitudinal forests types. (3) Results: The floristic groups were determined by altitude, temperature, and isothermality, but also some geomorphological variables and lithology were used. Plots located in low hills have higher alpha diversity compared to the high hills and dissected mountains. (4) Conclusions: Altitude is the most important factor responsible for the division of structural and floristic groups. In addition, those plots located on the whitish tuff have higher alpha value diversity compared with plots in andesitic tuffs. Precipitation on the wettest quarter (>839 mm) and isothermality (>90.5) are the most relevant climatic factors driving the floristic classification. Full article

Revealing the genetic population structure in abundant avian species is crucial for understanding speciation, conservation, and evolutionary history. The Red-backed Shrike Lanius collurio, an iconic songbird renowned for impaling its prey, is widely distributed as a breeder across much of Europe, Asia Minor and western Asia. However, in recent decades, many populations have declined significantly, as a result of habitat loss, hunting along migration routes, decrease of arthropod food, and climate change e.g., severe droughts in Africa. Within this context, gene flow among different breeding populations becomes critical to ensure the survival of the species, but we still lack an overview on the genetic diversity of the species. In this paper, we analyzed the mitochondrial cytochrome b gene (mtDNA) and the cytochrome c oxidase subunit 1 gene (mtDNA) of 132 breeding Red-backed Shrikes from across the entire breeding range to address this knowledge gap. Our results revealed consistent genetic diversity and 76 haplotypes among the Eurasian populations. Birds are clustered in two major groups, with no clear geographical separation, as a direct consequence of Pleistocene glaciations and apparent lineage mixing in refugia. This has led to genetic panmixia. Full article

Invertebrate diversity can be a key driver of ecosystem functioning, yet understanding what factors influence local biodiversity remains uncertain. In many marine and terrestrial systems, facilitation cascades where primary foundation and/or autogenic ecosystem engineering species promote the settlement and survival of a secondary foundation/engineering species have been shown to enhance local biodiversity and ecosystem functioning. We experimentally tested if a facilitation cascade occurs among eelgrass (Zostera marina), pen clams (Atrina rigida), and community diversity in temperate seagrass beds in North Carolina, U.S.A., and if this sequence of direct positive interactions created feedbacks that affected various metrics of seagrass ecosystem function and structure. Using a combination of surveys and transplant experiments, we found that pen clam density and survivorship was significantly greater in seagrass beds, indicating that eelgrass facilitates pen clams. Pen clams in turn enhanced local diversity and increased both the abundance and species richness of organisms (specifically, macroalgae and fouling invertebrate fauna)—the effect of which scaled with increasing clam density. However, we failed to detect an impact of pen clams on other seagrass functions and hypothesize that functioning may more likely be enhanced in scenarios where secondary foundation species specifically increase the diversity of key functional groups such as epiphyte grazers and/or when bivalves are infaunal rather than epifaunal. Our findings add to the growing amount of literature that demonstrates that secondary foundation species are important drivers of local biodiversity in marine ecosystems. Further experimentation is needed that directly examines (i) the role of functional versus overall diversity on seagrass functions and (ii) the relative importance of life-history strategy in determining when and where engineering bivalves increase biodiversity and/or functioning of seagrass beds. Full article

Signal crayfish, as an invasive alien species in Europe, have caused impacts on aquatic communities and losses of native crayfish. Eradication of recently established populations may be possible in small ponds (<2.5 ha) and short lengths of small watercourses using a nonselective biocide. Between 2004 and 2012, a total of 13 sites in the U.K. were assessed for suitability. Six were treated with natural pyrethrum and crayfish were successfully eradicated from three. In Norway, five sites were assessed and two sites were treated with a synthetic pyrethroid, cypermethrin, both successfully. In Sweden, three sites were treated with another synthetic pyrethroid, deltamethrin, all successfully. Defining the likely extent of population was critical in determining the feasibility of treatment, as well as the ability to treat the whole population effectively. Important constraints on projects included site size, habitat complexity, environmental risks, cooperation of landowners and funding availability. Successful projects were manageably small, had good project leadership, had cooperation from stakeholders, had access to resources and were carried out within one to three years. Factors influencing success included treating beyond the likely maximum geographical extent of the population and taking care to dose the treated area thoroughly (open water, plus the banks, margins, inflows and outflows). Recommendations are given on assessing the feasibility of biocide treatments and project-planning. Full article