Coastal rock pools of Lake Superior in North America are a mosaic of biologically rich ecosystems that vary in their physical morphology and chemistry. Occurring in bedrock depressions between the forest edge and the lake, the aquatic communities in these pools are susceptible to impacts from both international shipping lane traffic and changing climate patterns. Individual pools are small, but the number of pools across the coastal landscape provide an expansive network of variable habitats, with >70,000 pools found in the 48 km of shoreline in the study area. In this study, we aimed to understand the relationships between aquatic invertebrates and abiotic conditions in coastal pools. The Dipteran family Chironomidae were studied because of their ubiquity and diversity in freshwater systems. We used nonmetric multidimensional scaling to describe how Chironomidae diversity and abundance were related to seasonality, habitat, and environmental factors (water chemistry and trace metals). We observed 2 distinct chironomid assemblages associated with habitat type based on chemical characteristics and physical location on the shoreline, including numerous rheophilic species near the lake, where consistent wave wash mimics lotic conditions, and species preferring lentic-mesotrophic conditions near the forest edge. Conductivity and pH were higher in pools near the lake, whereas temperature and dissolved O-2 varied seasonally. Nutrients and metals differed between study sites and pools at each site. At 2 sites, naturally occurring Cu and Al were found at concentrations that exceeded estimated chronic toxicity for sensitive aquatic invertebrates. Pool separation of known tolerant or sensitive species indicated a potential response to elevated metal concentrations. Metals may be an important driver for sensitive species occupancy and survival in certain pools, raising more general concerns regarding community responses to natural conditions in pristine environments.

ABSTRACT Chironomid communities of the upper St. Croix River, Wisconsin, were sampled for pupal exuviae at four locations monthly from April to October, 2007. Species richness was very high, with 252 species from 73 genera, dominated by the subfamilies Chironominae and Orthocladiinae. Most studies of lotic systems find fewer than 150 chironomid taxa, and often less than 100. The high richness may be due to regional conditions that support diverse aquatic communities, such as thermal regime, typical landscape patterns such as elevated mid-order stream diversity or increased β-diversity in headwaters, or the collection method which can detect species from adjacent habitats. There were 35 species that are atypical of lotic systems and some may have occupied microhabitats or adjacent habitat that more closely matches their preferences. Twenty-one species, mostly in Orthocladiinae, had range expansions into the western Great Lakes region or appear to be previously undescribed for the Nearctic. Sixty morphotypes, dominated by 41 Chironominae, did not fit any published exuviae descriptions.

Associated Procladius Skuse (Holotanypus Roback) material from the Sublette collection was found to have specimens with undescribed immature stages. Pupal exuviae of two species are described for the first time: P. barbatulus Sublette and P. clavus Roback. Adult and larval features are included for P. barbatulus. In addition, specimens of Nearctic P. denticulatus Sublette are compared to Palearctic P. signatus (Zetterstedt) to determine if exuviae can separate these species or suggest that P. signatus is a senior synonym. Finally, associated pupal and larval traits of P. prolongatus Roback are compared to the original description, corroborating the theory that features are unique enough to warrant subgeneric status.

Rapid bioassessment protocols using benthic macroinvertebrate assemblages have been successfully used to assess human impacts on water quality. Unfortunately, traditional benthic larval sampling methods, such as the dip-net, can be time-consuming and expensive. An alternative protocol involves collection of Chironomidae surface-floating pupal exuviae (SFPE). Chironomidae is a species-rich family of flies (Diptera) whose immature stages typically occur in aquatic habitats. Adult chironomids emerge from the water, leaving their pupal skins, or exuviae, floating on the water's surface. Exuviae often accumulate along banks or behind obstructions by action of the wind or water current, where they can be collected to assess chironomid diversity and richness. Chironomids can be used as important biological indicators, since some species are more tolerant to pollution than others. Therefore, the relative abundance and species composition of collected SFPE reflect changes in water quality. Here, methods associated with field collection, laboratory processing, slide mounting, and identification of chironomid SFPE are described in detail. Advantages of the SFPE method include minimal disturbance at a sampling area, efficient and economical sample collection and laboratory processing, ease of identification, applicability in nearly all aquatic environments, and a potentially more sensitive measure of ecosystem stress. Limitations include the inability to determine larval microhabitat use and inability to identify pupal exuviae to species if they have not been associated with adult males.

Coastal habitats are an ecotone between aquatic and terrestrial ecosystems. Depressions on volcanic bedrock shores of Lake Superior form small pool habitats that are influenced to various degrees by their spatial context and that relate to differences in mechanisms of disturbance. A total of 71,931 coastal pools were mapped and measured, and amphibian occupants were identified along 48km of shoreline at Isle Royale National Park, where coastal rock pool habitats were abundant. Generally, mean depth of pools was 0.11m, with a mean surface area of 0.6m2, although maximum measurements were 1.5m and 378m2, respectively. Three strongly defined zones occurred, with bedrock near the lake having a low slope and more numerous, smaller, and shallower pools; bedrock near the forest edge had a steeper slope and fewer, larger, and deeper pools; and a median zone occurring between. A single offshore location, Passage Island, had nearly 63% of all pool abundance. Two amphibian species were typical of coastal pools, the chorus frog (Pseudacris triseriata) and blue-spotted salamander (Ambystoma laterale), while spring peeper (Pseudacris crucifer) was uncommon and probably incidental to coastal habitats. These three species were significantly more abundant in mid-shore pools. Four other amphibian species were only rarely detected. Both coastal habitat density and chorus frog abundance were highest at localities directly adjacent to an international shipping lane. As a result of intriguing spatial distributions and potential for impacts from coastal pollution, chorus frog in particular reveals that coastal ecology can be unique from inland contexts and have important management implications at the land–water interface.

Chironomid pupal exuviae were collected from coastal rock pools at Isle Royale National Park, Michigan, from April to October in 2009 and 2010. Pools in bedrock depressions were separated into those higher on the shore, where desiccation is likely an important disturbance, and lower on the shore, where wave-wash from Lake Superior is likely a fundamental influence. The 102 species collected represent 42 genera in six subfamilies. The distribution and ecology of each species is summarized. Also included are remarks on species with significant range expansions, either with Palearctic or Nearctic disjunct ranges, or novel habitat use among species that are typically considered lotic but occur in splash zone pools at Isle Royale.

Chironomidae are typically abundant in freshwater habitats and can be good indicators of ecological health. Coastal rock pools of barrier islands were sampled to determine how communities varied spatially between two horizontal zones, defined by wave disturbance and distance from shore, and from island-to-island. Pupal exuviae were collected monthly from pool surfaces to assess species composition, true community richness, and alpha and beta diversity. Cluster analyses were used to determine geographic community variation. A majority of species were rare, while three species dominated relative abundances. Zonal differences were significant, diversity was greater in near-shore pools overall, and few species occurred in both zones. Communities were more species-rich than expected based on prior studies in similar habitats. Community clusters were not strongly differentiated but suggested increased dispersal challenges at wider gaps between islands. Higher diversity near the shore and geographic clustering of communities are important to consider when planning for remediation activities following pollution events such as ship groundings or oil spills. In general, baseline coastal studies and conservation planning should consider aquatic invertebrates when pool habitats are present.

Understanding the phenology of emergences can be useful in determining seasonal chironomid life cycle patterns, which are often influenced by ice cover and temperature in cold climates. Lake Superior is the largest lake in North America and with a mean surface temperature of 3.9 °C influences regional climate. Coastal pools at Isle Royale, a wilderness archipelago in the northern part of the lake, occur in dense patches on low-gradient volcanic bedrock between the lakeshore and forest, creating variable microhabitats for Chironomidae. Four sites were sampled monthly from April to October, 2010. Surface-floating pupal exuviae were collected from a series of pools in two zones: a lower zone near the lake influenced by wave splash, and an upper zone near the forest and influenced by upland runoff. We used Jaccard’s and Whittaker’s diversity indexes to test community similarity across months. Temperature loggers in pools collected hourly readings for most of the study. Assemblage emergences were stable in upper pools, with significant similarity across late spring and summer months. Assemblages were seasonally variable in lower pools, with significant dissimilarity across spring, summer, and fall months. Few species in either zone were unique to spring or fall months. However, many summer species in the splash zone had a narrow emergence period occurring during calm weather following distinct increases in mean water temperature. Regardless of input of cold lake water to the lower zone, pools from both zones generally had corresponding temperature trends.

Chironomidae (Diptera) are among the most diverse and widespread aquatic insects, with approximately 5,500 species described. However, prior to the present work, only 4 species of Chironomidae were reported from the Bahamas. The goal of our study was to provide basic species data on the Chironomidae of San Salvador Island. In March of 2012, a variety of aquatic habitats representing fresh to saline waters were sampled for chironomid larvae and pupal exuviae. Twelve species were found: Chironomus Meigen (3 morphospecies), Dicrotendipes sp. A sensu Epler, Polypedilum (Tripodura) scalaenum group (1 morphospecies), Goeldichironomus fluctuans Reiss, Tanytarsus mendax Kieffer, Tanytarsus cf. confusus Malloch, Ablabesmyia (Sartaia) metica Roback, Labrundinia maculata Roback, Paramerina anomala Beck & Beck, and Djalmabatista pulchra (Johannsen). All of these are new records for the Bahamas, with Tanytarsus mendax and Paramerina anomala new for the Neotropical region.

Collections of floating chironomid pupal exuviae are used to monitor water quality and assess ecological conditions. Factors controlling exuviae sinking rates are not well known, although they should have an effect on conclusions that can be drawn from collections. The current study was conducted to determine the rate of sinking under controlled laboratory conditions using water from three streams with different nutrient levels. Sinking rates ranged from less than a day to seven days, depending on microbial activity, nutrient concentrations, temperature and turbulence. Results also varied by genus, with pupal exuviae of Chironomus riparius , Diamesa nivoriunda , Orthocladius ( Euorthocladius ) thienemanni and Eukiefferiella sp. used in experiments. Four species of bacteria and eight genera of fungi colonized and metabolized exuviae, with bacteria dominant early and fungi dominant later in the decomposition process. Decomposition was faster in lightly chitinized abdominal conjunctive areas, which resulted in exuviae breaking apart and sinking. Examination of untreated, dewaxed and dewaxed-deproteinized exuviae indicated that untreated exuviae sank faster. Waxes appeared important for colonization and initial microbial metabolization was delayed when waxes were removed. Results confirm the importance of biological degradation of exuviae in determining floatation times. We predict that streams and other waterbodies with high dissolved nutrients will result in rapidly sinking exuviae, while exuviae in low nutrient waterbodies will float longer. Article submitted 1. October 2014, accepted 18. November 2014, published 22. December 2014.

Moose (Alces alces [L]) droppings were sampled in June-August, 2007, in Isle Royale National Park, a remote wilderness island in Lake Superior, to characterize biodiversity of the park's moose dung fauna. Twelve Diptera and nine Coleoptera species were obtained, for a total of 21 insect taxa. Twenty of the taxa are newly recorded colonists or visitors to moose dung. The Diptera were Psychodidae, Anthomyiidae, Muscidae and representatives of three other families, and Coleoptera consisted of three species in each of Scarabaeidae, Staphylinidae and Histeridae. Species per sample ranged from two in early June to nine in mid-July, and a species accumulation curve indicated a total of six more species remain to be detected. The relatively depauparate nature of the island's dung insect fauna may be attributed to absence of other large herbivores,. to geographic isolation from source populations on adjacent mainland, or to distinct physical or biological properties of moose dung. Among reared specimens, Hylemyza partita (Meigen) (Anthomyiidae) and moose fly, Haematobosca alcis (Snow) (Muscidae) required approximately 3 weeks to complete development from egg to adult. Projections from weather records on the island indicated the two species could have completed as many as five generations between dates of last spring frost in May and first autumn frost in November.