Robert W. Sites

AQUATIC MACROINVERTEBRATE DIVERSITY OF PLAYA WETLANDS: THE ROLE OF LANDSCAPE AND ISLAND BIOGEOGRAPHIC CHARACTERISTICS

Wetland habitats continue to be lost at a unsettling rate, especially freshwater emergent wetlands that are isolated geographically. These are the predominant wetlands found in arid and semi-arid environments, where they serve as foci of regional biodiversity. This is especially true of the playa wetlands of the Southern High Plains of Texas, USA. The factors that determine and maintain biotic diversity in these wetlands are understood poorly. Consequently, this study examined the effect of island biogeographic and landscape features on the diversity of aquatic macroinvertebrates in playa wetlands. Macroinvertebrates were collected from playas three times during the spring and summer of 1994 and categorized as resident or transient taxa based on life history strategies. Diversity was estimated using taxonomic richness (richness) and Fisher’s log-series alpha (α). Surrounding land-use practices influenced resident richness, whereas playa surface area affected resident and transient richness, as well as resident α. However, relationships differed among sampling dates. Regression analyses suggested that transient richness and α were influenced more by insular characteristics than by landscape features. The converse was true for resident richness and α. Therefore, both insular and landscape characteristics affected the diversity of macroinvertebrates in playa wetlands, but impacts were dependent on life-history strategy and time since inundation (i.e., sampling date). Consequently, conservation and management efforts targeting macroinvertebrates in playa wetlands will need to focus on the wetlands and characteristics of adjacent watershed features.

Microhabitat associations of three species of Dryopoidea (Coleoptera) in an Ozark stream: a comparison of substrate, and simple and complex hydraulic characters

Microhabitat associations of adults and larvae of Stenelmis lateralis Sanderson, Optioservus sandersoni Collier (Coleoptera: Elmidae) and larvae of Psephenus herricki (DeKay) (Coleoptera: Psephenidae) were examined within riffles of an Ozark stream in Missouri. The invertebrate fauna was sampled from 150 quadrats, and each quadrat was characterized by a suite of substrate, simple hydraulic, and complex hydraulic variables. Larvae were assigned to size classes for analyses. MANOVAs were performed to determine if differences existed between sites of presence and absence for each of the three species separately. Subsequently, ANOVAs and Bonferroni sequential adjustments were performed to determine differences in each habitat variable that are related to presence or absence of each group. Multiple regression was performed to determine which habitat variables were important determinants of density for each taxon. Finally, discriminant function analyses were performed to determine the degree of overlap in microhabitat associations of each group. A clear distinction was seen between sites of occurrence and absence for P. herricki, and for larvae of each elmid species (MANOVAs). For P. herricki, current velocity and the complex hydraulic characteristics of Reynolds number and boundary Reynolds number were important in determining beetle presence. In contrast, substrate characteristics were major determinants of presence for larvae of O. sandersoni and S. lateralis. In general, the density of each of the three species was related to a different subset of abiotic variables. For each species, the most definitive microhabitat associations were seen in the early instars. Microhabitat associations for larvae of each elmid species were size class-specific. Inclusion of complex hydraulic characteristics along with substrate and simple hydraulic characteristics provided greater resolution of microhabitat associations.

Submerged Rootmats: A Mesohabitat Harboring a Distinct Insect Community in Ozark Streams

ABSTRACT Three third order Ozark streams in different watersheds were sampled quantitatively to determine if rootmats harbored an insect community distinct from other lotic communities. Samples were taken from pools, riffles, and rootmats in each stream. The communities were compared based on taxonomic richness, abundance, diversity, and composition. Whereas diversity and richness were not significantly different among mesohabitats, abundance was greater in rootmats than in pools and riffles. The taxonomic composition of rootmat communities was more dissimilar to those of pools and riffles than were pool and riffle communities to each other. Of the 75 taxa collected, 13 were unique to rootmats and seven each to riffles and pools. Further, it appeared that several taxa, not necessarily unique to rootmats, utilized rootmats at some point in their life history (i.e., pupation, oviposition). The results indicate that submerged rootmats harbor a distinct and abundant insect fauna that likely plays an integral part in stream ecosystems.

Aquatic insects as umbrella species for ecosystem protection in Death Valley National Park

Under the United States Endangered Species Act (ESA), critical habitat for listed species is also protected. Many aquatic insects protected under the ESA are habitat-restricted, mainly to springs. Some of these species do not co-occur with ostensibly more charismatic vertebrates, and have the potential to act as umbrella species for aquatic ecosystems. We suggest that the flightless creeping water bug Ambrysus funebris La Rivers (Insecta: Heteroptera: Naucoridae) has the potential to be such a species. Endemic to a spring system in Death Valley National Park, it co-occurs with eight other endemic aquatic invertebrate species, but with no vertebrates. Therefore, its protection would facilitate protection of this desert oasis. Ambrysus funebris is a candidate for protection under the ESA because of its endemicity, a decline in abundance, and habitat degradation. To facilitate its use as an umbrella species, we report the first illustrated descriptions of the five nymphal instars of Ambrysus funebris La Rivers. Recommendations on its conservation and role as an umbrella species for conserving its habitat are presented. A synopsis of aquatic insect species protected or listed as candidates under the ESA indicates that spring-endemics predominate. We also present a list of potentially threatened and unprotected aquatic heteropterans in the western United States.

Two New Species of Leptohyphes (Ephemeroptera:Leptohyphidae) from Ecuador

Leptohyphes liniti New Species and Leptohyphes nicholsae New Species are described from larvae taken in Ecuador. Leptohyphes liniti has a highly developed ridge on the hind femora and otherwise is most similar to Leptohyphes tacajalo Mayo, also from Ecuador. Leptohyphes nicholsae is closely related to L. curiosus Lugo-Ortiz and McCafferty, described from Costa Rica, but differs in the presence of abdominal tubercles and color pattern.

The Ephemeroptera, Plecoptera, and Trichoptera of Missouri State Parks, with Notes on Biomonitoring, Mesohabitat Associations, and Distribution

Abstract Thirty-seven streams within 15 Missouri State Parks were sampled for immature and adult Ephemeroptera, Plecoptera, and Trichoptera (EPT) during 2002 and early 2003. Seven mesohabitats were sampled: riffle, run, leafpack, pool, no flow organic, bank, and silt/mud. Mesohabitat associations are reported for each species collected. All totaled, 34,251 EPT larvae were collected, all specimens of which were identified to the lowest taxon possible. Of approximately 70,000 adult specimens collected by blacklight and vegetation sweeping, 10,342 were examined and identified to the lowest taxon possible. Fifteen species endemic to the Interior Highlands and two species on the Missouri Species of Conservation Concern Checklist were collected. This research revealed a total of 213 species in 99 genera and 37 families of EPT in the designated state parks, representing 65% of the EPT fauna known from Missouri. Mesohabitat associations are reported for all species of larvae collected. Richness of mayflies and stoneflies was significantly highest during the spring season whereas richness of caddisflies was significantly highest during the fall. Richness of all three orders was highest in the riffle mesohabitat, and lowest in the pool and no flow organic mesohabitats. Many distribution records are reported and Serratella sordida McDunnough (Ephemeroptera: Ephemerellidae) and Triaenodes perna Ross (Trichoptera: Leptoceridae) were collected in Missouri for the first time.

Least-Desired Index for Assessing the Effectiveness of Grass Riparian Filter Strips in Improving Water Quality in an Agricultural Region

Abstract Unprotected streams within the agricultural Midwest region of the United States are subject to sedimentation, nutrification, and agricultural chemicals. Grass riparian filter strips (GRFSs) have been implemented as a best management practice to minimize sedimentation and associated materials that are harmful to aquatic ecosystems; however, few studies have examined the benthic community response to GRFS installation. This study introduces a least-desired index (LDI) multimetric approach of evaluating benthic communities in response to GRFS installation. LDI was determined in a reciprocal fashion to that of a benthic macroinvertebrate index of biotic integrity (B-IBI). When reference conditions are not available for the use of B-IBI, anti-reference sites, representing least-desired conditions, can be used in constructing an LDI. A B-IBI and LDI were constructed in the Claypan Till Plains Subsection of Missouri and comparatively used to evaluate two test sites where tall fescue GRFS were installed. Five metrics were used to develop the B-IBI and six for the LDI. The LDI tended to be more conservative at evaluation in comparison to the B-IBI. Paired t-tests showed that LDI and B-IBI were significantly different at scoring test sites. The LDI assessed both test sites as showing no response to GRFS installation, whereas the B-IBI suggested moderate improvement. The LDI was considered to be a better index for evaluation because the streams used to develop the B-IBI were not suitable reference sites. An argument for the use of chironomid based metrics in low gradient agricultural streams is presented.

The Influence of Adjacent Land Uses on Macroinvertebrate Communities of Prairie Streams in Missouri

ABSTRACT The impact of adjacent land uses on aquatic macroinvertebrate communities was assessed in three low gradient, prairie streams in Missouri, USA. Aquatic macroinvertebrates were collected from 17 sites during fall 1999, and spring and summer 2000; each site was bordered by a single land use practice. We found no significant differences in taxa diversity [richness, abundance, or Fishers log-series a (FLSA)] or composition metrics (richness and abundance of EPT taxa, functional feeding groups or Chironomidae) attributable to adjacent land use during any season. However, FLSA was significantly affected by the distance of a site from the beginning of the perennial stream during the spring and summer. Little of the variation in taxa diversity was attributable to physicochemical factors. However, these factors were more important in explaining differences in diversity among sites during the drought (fall 1999) than in other seasons. Taxonomic composition of the macroinvertebrate community effectively discriminated among sites bordered by different land uses. Although compositional differences were season-specific, predators and chironomids were the most important groups accounting for signiticant differences among land use groups regardless of season. Moreover, compositional analysis, based on proportional abundances of taxa, revealed the importance of both stream identity and adjacent land use to community structure.

Review of the Ambrysus stali La Rivers species complex (Heteroptera: Nepomorpha: Naucoridae) with the description of a new species from Mesoamerica

The Neotropical Ambrysus stali La Rivers species complex is reviewed and includes A. bifidus La Rivers & Nieser, A. scolius La Rivers, A. stali La Rivers, and A. tricuspis La Rivers. Ambrysus oblongulus Montandon is removed as a member of this complex. Features uniting these species are related to male genitalia and associated structures. Ambrysus maya n. sp. is the fifth species in the complex and is described from Belize, Guatemala, and Mexico based on specimens from recent collecting and museum collections.

A Review of Ptilomera (Heteroptera: Gerridae) in Thailand, with Descriptions of Three New Species

Abstract Three new species of Ptilomera (P. jariyae, P. kra, and P. tennaserim) were collected from mountain streams in western and southern Thailand, and they are described and illustrated herein. These new species bring the number of described species of this genus in Thailand to seven. In addition, the winged form of P. fang Polhemus is described. Diagnoses for males and females are provided for all seven species occurring in Thailand, along with distributional records and maps.