Somatochlora Hineana Research Articles

Groundwater characterization of the eastern Minesing Wetlands in support of the endangered Hine’s emerald dragonfly (Somatochlora hineana)

The Minesing Wetlands contain Canada’s only known population of Hine’s emerald dragonfly (HED), a species listed as endangered since 2011. The HED relies on groundwater discharge areas to complete its life cycle and therefore the population is potentially sensitive to changes in groundwater. The goals of this study were to, (1) characterize groundwater discharge to the eastern portion of the Minesing Wetlands, which corresponds to the HED habitat, (2) document any significant changes in groundwater chemistry since a 1998 study, and (3) establish a comprehensive baseline water quality data set to facilitate future comparisons. Consistent with HED habitats in the USA, the chemistry of Minesing Wetlands groundwater was dominated by calcium and bicarbonate. Low groundwater chloride and nitrate concentrations indicated minimal impact from activities such as road salt application and fertilizer use. Nitrate was generally only found at the wetland margin where groundwater springs emerged from the base of the uplands. The dominant form of inorganic nitrogen in wetland groundwater was ammonium (max = 1.5 mg N/L), and soluble reactive phosphorus concentrations were also relatively high (8 to 122 µg/L). The most consistent change in wetland groundwater chemistry between the 1998 study and samples collected in 2015–2017 was that chloride concentrations in 10 of 23 wells increased over time, however the maximum mean well chloride (11.6 mg/L) remained well below the guideline for the protection of aquatic life (120 mg/L). To preserve HED habitat, potential impacts to groundwater need to be considered during land use planning for the recharge area.

Persistence and accumulation of environmental DNA from an endangered dragonfly

Detection of environmental DNA (eDNA) has become a commonly used surveillance method for threatened or invasive vertebrates in both aquatic and terrestrial environments. However, most studies in this field favor vertebrate target species. Environmental DNA protocols can be especially useful for endangered invertebrates such as the Hine’s emerald dragonfly (Somatochlora hineana) where conservation efforts have been greatly hindered by training, time, overall costs, and environmental impacts associated with conducting surveys in the calcareous fens occupied by this species. An essential step in developing such a protocol is to evaluate the dynamics of eDNA concentration under controlled conditions. We used the quantitative polymerase chain reaction (qPCR) to examine seasonal shifts in the persistence and net-accumulation of eDNA from captive S. hineana larvae in experimental mesocosms at temperatures corresponding with their overwintering (5.0 °C) and active (16.0 °C) seasons. Environmental DNA persisted longer at 5.0 °C but accumulated more readily at 16.0 °C. Differences in the accumulation and persistence of eDNA reflect differences in the longevity of eDNA at different temperatures and seasonal differences in larval S. hineana behavior. This study highlights the importance of considering how seasonal changes in temperature influence not only the speed of eDNA degradation but also the target species’ eDNA shedding rates.

Contrasting Ozark and Great Lakes populations in the endangered Hines emerald dragonfly (Somatochlora hineana) using ecological, genetic, and phylogeographic analyses

AbstractThe federally endangered species Hine's emerald dragonfly (Somatochlora hineana) is found in fens surrounding the Great Lakes region and in a small portion of the Missouri Ozarks. Most previous work has focused on the populations in the Great Lakes region. We present mark/recapture studies and genetic surveys to address the status of the Ozark populations. The densities and genetic diversity tend to be higher in the Ozarks than in the Great Lakes region. A phylogeographic analysis indicates that the Ozarks, with its unglaciated fens, is the likely source for the populations currently inhabiting the formerly glaciated Great Lakes region, and genetic diversity decreases with increasing distance from the Ozarks. This work illustrates the inadequacy of using geography alone to identify a population as marginal and of less conservation concern. We also reanalyzed genetic data on the Great Lakes populations, where several populations have been extirpated over the last several decades. We show that the populations in the Great Lakes region have already lost more than 30% of their genetic diversity over just several decades, and the phylogeographic analysis indicates that increased fragmentation is a possibility in this region due to local extirpations. Ecologically and genetically, the Ozark populations should have a high priority in management plans, and the high rate of loss of genetic diversity and potential fragmentation indicates that continued monitoring and management is needed in the Great Lakes region for this highly endangered dragonfly.

The complete mitochondrial genome of Hine’s emerald dragonfly (Somatochlora hineana Williamson) via NGS sequencing

Here, we report the complete mitochondrial genome of the endangered Hine’s emerald dragonfly (HED), Somatochlora hineana Williamson. Data were generated via next generation sequencing (NGS) and assembled using a mitochondrial baiting and iterative mapping approach. The full length circular genome is 15,705 bp with 26.6% GC content. It contains the typical metazoan set of 37 genes: 13 protein-coding genes, 22 transfer RNA (tRNA) and 2 ribosomal RNA (rRNA) genes, and an A + T-rich control region. To our knowledge, this is the first report of the complete HED mitogenome.

Single-sample estimation of effective population size in several populations of the endangered Hine’s emerald dragonfly

AbstractHine’s emerald dragonfly (Somatochlora hineana) is the only odonate on the US Endangered Species list. It prefers discrete fen-and-wet-meadow habitat from Ontario, Canada, to Missouri, USA. This habitat has been destroyed across much of S. hineana’s range. Its conservation genetics were assessed by microsatellite analysis in a previous study. We applied 2 common single-sample estimators to the same data set to estimate effective population size (Ne), or effective number of breeders, in 5 populations (separated into adult and naiad stage classes) across the species’ range in 2008 and 2010–2011. Populations of the species in the Upper Peninsula of Michigan, the Door Peninsula of Wisconsin, and along the Des Plaines River Valley in Illinois are made up of individuals collected from multiple sites, but the other 2 populations, at Cedarburg Bog, Wisconsin, and along the Lower Wisconsin River, consist of samples from single habitats disjunct from other known sites. Ne for S. hineana were similar to thos...

The potential of diversion structures to reduce roadway mortality of the endangered Hine’s emerald dragonfly (Somatochlora hineana)

Roadways near wetlands and ponds inflict high roadkill rates on a wide variety of taxa. For threatened or endangered species that typically do not have large adult populations, fast reproduction rates, and/or rapid recolonization rates, such mortality is likely to have significant population consequences. Thus, exploring ways to reduce roadkill rates will have considerable conservation benefits. In this study, we evaluate whether a diversion structure can be used to modify flight behavior of the endangered Hine’s emerald dragonfly (Somatochlora hineana) in ways that would reduce roadway mortality. Flight behavior of adult S. hineana was observed with and without two 3 m high nets spaced at 6 and 12 m to simulate a small and a larger roadway. The netting significantly deterred (p < 0.0001) S. hineana adults from crossing the simulated roadway. Flight height was also influenced significantly (p = 0.0025) with flight heights over the 6 m net spacing being higher than those over the 12 m spacing. This study suggests that the use of diversion netting in areas where sensitive dragonfly species interact with motor vehicles might aid in reducing roadway mortality and might help reduce the overall impact of roadways on wetland ecosystems.

Conservation in Hine’s sight: the conservation genetics of the federally endangered Hine’s emerald dragonfly, Somatochlora hineana

Hine’s emerald dragonfly (Somatochlora hineana) is distributed in discrete fen and wet meadow habitats over its range from Ontario, Canada, to Missouri, USA. Habitat destruction in the vicinity of Chicago, IL, and other areas lead to its designation as an US federal endangered species in 1995. Our main goal was to delineate the population genetic structure of the species within the northern recovery unit centered on the Door Peninsula in Wisconsin and the southern recovery unit in the Des Plaines River Valley near Chicago, IL. Sites on the Door Peninsula, WI, are in a matrix of agricultural development and second-growth forest and were used as a best available approximation of a pristine system for the dragonfly. We nondestructively sampled 557 adults and larvae from 16 sites in Illinois, Michigan, and Wisconsin from 2008 through 2011 and used ten microsatellite markers to estimate levels of genetic variability, and genetic structure. Mean allelic richness across all sites and years was 5.03 (±0.64) and expected heterozygosity was 0.52 (±0.032). Northern and southern recovery units as designated in the original recovery plan were genetically distinct. We delineated two genetic populations in the northern unit and three within the southern including two disjunct sites.

Dennis Paulson: Dragonflies and damselflies of the east

This welcome guide is a companion to an earlier volume in the same series (Paulson 2009) dealing with the western fauna of North America, and follows the same clear and informative format. As a fully illustrated field guide to adults of the 336 species of Odonata in the region, it has the primary goals of enabling identification and presenting material on natural history to prompt wide interest in these already popular insects. The two books together comprise authoritative guides to the North American representatives, with the excellent colour photographs of living adults a major feature. The book falls into three sections. The initial introduction is a wide-ranging account of the natural history of the Odonata, reflecting Paulson’s wise perspective that ‘they are such interesting animals that all who observe them in the field should know something about their lives’. It includes original and very readable accounts of many aspects of adult behaviour and biology, again with abundant high quality colour photographs adorning the book. I particularly liked the use of labeled colour photographs (rather than more conventional line diagrams) to indicate morphological features. Dennis Paulson writes enthusiastically and lucidly, and this section of the book encapsulates much very practical advice from his own extensive experiences with Odonata. The values of collecting (including roles in conservation) are noted, together with clear directions for specimen treatment. The short section on conservation is a succinct summary of threatening processes, and the limitations of the range maps given for each species are noted. Encouragingly, it is also noted (in context, p. 371) that the only odonate (Somatochlora hineana) listed under the United States Endangered Species Act is now known to be ‘much more widespread than was known when it was listed’. The two major sections of the guide are systematic treatments of the damselflies (87 species) and dragonflies (249 species), each given a common name, some novel. The species accounts each have one or more photographs, a small range map, and the accompanying text written in a standard, easily comparable, format. That text includes sections on descriptive features and identification, detailing differences in appearance from related or similar-looking taxa, notes on natural history, the kinds of biotope frequented, flight season (with notes on differences across the range, where this is broad). In cases where examination of terminalia or other morphology is needed for clear identification (such as for the ‘bluets’, Enallagma) clear outline drawings of the features are gathered together for easy comparison, and given on clearly demarcated blue pages to render them easily found by ‘page-flicking’. That use is facilitated also by a very comprehensive index to scientific and common names, a glossary of technical terms, and a short array of useful references and resources available to discover more about Odonata. The book is compact, excellently produced and presented on high quality paper. It will have wide and enduring use, and be of immense value to students of Odonata in North America, and as an exemplar for emulation, and envy, elsewhere.

Nonlethal Tissue Sampling Techniques and Microsatellite Markers Used for First Report of Genetic Diversity in Two Populations of the Endangered Somatochlora hineana (Odonata: Corduliidae)

Abstract Techniques for obtaining DNA noninvasively or nonlethally are highly desirable in molecular genetic studies of protected species, and several advances have been made in these types of sampling and extraction techniques. Insects present a unique set of difficulties in this regard that are not present when working with most vertebrates. This study evaluated the effectiveness of several nonlethal sampling techniques for larval and adults of the federally listed endangered dragonfly Somatochlora hineana (Williamson) (Odonata: Corduliidae). Fecal pellets and shed exuviae from captive S. hineana larvae did not provide high enough quality DNA for microsatellite analyses. Invasive, but nonlethal, wing clips from adults and tarsi from larvae provided high-quality DNA that amplified 10 microsatellite markers for this species. Ten loci were polymorphic in 94 specimens with four to 14 alleles per locus. Two populations in WI had average observed heterozygosity of 0.47, which is within the range reported for other odonates. Our sampling techniques and these new microsatellite markers provide an essential tool for determining the genetic structure of S. hineana populations throughout its range.

Evaluating the non-consumptive, positive effects of a predator in the persistence of an endangered species

Failure to consider both the consumptive and non-consumptive effects of predators on prey can lead to erroneous conclusions about the net effect of the relationship. The predatory devil crayfish, Cambarus diogenes Girard functions as an ecosystem engineer constructing extensive burrow systems through aquatic habitats. Despite crayfish posing a serious predation threat, preliminary data indicate that the federally endangered Hines Emerald dragonfly larvae, Somatochlora hineana Williamson regularly inhabit crayfish burrows. During late summer, S. hineana larval habitat dries up; leaving crayfish burrows as some of the only wetted habitats. Thus, C. diogenes can affect S. hineana through both direct, negative and indirect positive effects. We examined the positive role of crayfish burrows as drought refuges, and the threat of predation by C. diogenes on S. hineana larvae. Monthly field sampling indicated that S. hineana use open channel areas in spring and early summer moving into burrow systems in mid summer when channel areas normally dry. Laboratory experiments and field observations confirmed that crayfish prey on S. hineana larvae. Adult crayfish were a larger predation threat than juvenile crayfish. Despite their negative predatory impact, removal of crayfish from burrows in the field did not enhance densities of S. hineana larvae. Although S. hineana may face the threat of predation in burrows, they face a greater risk of desiccation if they remain in the open channel. These results lead to the counterintuitive conclusion that the maintenance of a predator is important for conserving an endangered prey species.

Protecting more than the wetland: The importance of biased sex ratios and habitat segregation for conservation of the Hine’s emerald dragonfly, Somatochlora hineana Williamson

Within species habitat use may depend on age, season or sex of an individual. The distribution of males and females may vary both temporally and spatially due to differences in the costs of reproduction and the distribution of critical resources. Conservation of a species requires knowledge of the habitat use of both sexes in order to predict the population size and protect all habitats that a species requires. Adult dragonfly populations often have highly male-biased sex ratios at the breeding habitat. This bias has been attributed to females using alternative habitats to avoid male harassment, or to high female mortality. We monitored adult Hine’s emerald dragonfly ( Somatochlora hineana Williamson) populations, in breeding and non-breeding habitats in Door County, Wisconsin and found significant differences in habitat use between males and females. Males primarily used wetland habitats, while females primarily used dry meadows and marginal breeding habitats, only coming into wetlands to lay-eggs or find mates. We assessed food resources in the different habitats and found that high quality insect prey (primarily adult Diptera) were more available in the wetland habitat, indicating that these areas were likely a more productive foraging area for adult dragonflies. The fact that females appear to avoid the wetland habitat is consistent with the hypothesis that male harassment alters female distribution patterns. Consideration of the patterns of habitat use by S. hineana indicates the need to develop a broader understanding of the importance of non-wetland areas in the conservation of wetland species.

Evaluating exuvia collection as a management tool for the federally endangered Hine’s emerald dragonfly, Somatochlora hineana Williamson (Odonata: Cordulidae)

Reliable population density estimates are crucial for monitoring endangered species. Many species are difficult to capture or range over large areas, making direct monitoring of populations through capture or observation extremely challenging. In such cases, indirect methods of assessing populations can be the only source of reliable information. We examined whether the discarded exoskeleton of the last larval instar (exuvia), left behind when dragonflies emerge into the adult stage, could be used to predict larval densities and provide life history information for the federally listed endangered, Hine’s Emerald Dragonfly ( Somatochlora hineana). Using standardized protocols, we collected exuvia within six 2 × 2 m plots in an ephemeral wetland in Door County, Wisconsin during spring and summer of 1999 and 2000. S. hineana is a “summer emerger”, with more than 95% of the emergence occurring from late June until mid-July. Based on time of emergence and the flight period, adults appear to live a month or longer. The sex ratio at emergence did not differ significantly from a 1:1 ratio and emergence was synchronous between the sexes. Estimates of larval population density using exuvial data were similar to those obtained through intensive direct sampling for larvae. Exuvial collections provide a reliable estimate of larval population density, help link larval ecology to adult ecology and are a useful tool for assessing habitat suitability. Although sampling exuviae requires repeated searching on particular sites, less expertise and fewer people are required for this type of sampling, indicating that exuvial surveys can be a very effective tool for monitoring populations of endangered dragonflies.

Distribution, Habitat, and Field Biology of Somatochlora hineana (Odonata: Corduliidae)

Somatochlora hineana Williamson is among the most endangered Odonata in the United States. Populations of S. hineana were discovered in Illinois (1988) and Wisconsin (1989), and status surveys were conducted there 1990–1993. Adults were observed 30 May–8 September in Illinois and 27 June–23 August in Wisconsin. S. hineana habitat can be characterized as shallow, calcareous, spring-fed marshes or the marshy margins of small, sluggish, calcareous streams. Notes are presented on feeding behavior, male territorial patrols, copulatory behavior, and oviposition. The previously unknown nymph was discovered. The holotype and allotype of S. hineana were compared with specimens from Illinois, Ohio, and Wisconsin. No consistent morphological differences were noted.