Hawaiian Freshwater Polychaeta: A Potentially Substantial Trophic Component of Stream Depositional Habitats

In this paper we report the widespread occurrence of large annelids (Polychaeta: Nereididae) in Hawaiian stream depositional habitats, drawing attention to the lack of knowledge of Hawaiian stream energetics. Specimens of Namalycastis sp. were collected from five Hawaiian Islands from May–July 1995 and from the island of Maui from July–December 1999 and April–July 2000. Most specimens collected were N. hawaiiensis, while two specimens of N. abiuma were collected from a single site on the island of Molokai. Specimens were collected from elevations ranging from 3–240 m; several collections were from sites above at least one major (\u3e 15 m high) waterfall. Habitats were characterized by slow-moving or stagnant water, water temperatures ranging from \u3c 18–29 C, mixed gravel and sand substrates with organic detritus. Specimens were found among roots of vegetation along stream edges, in small lava pockets, buried in loose gravel, and in depressions between, under, and inside porous rocks. Body lengths of preserved specimens ranged from ~ 9 to 150 mm among islands and streams between years and seasons. Polychaetes were usually abundant in these habitats indicating a nearly ubiquitous distribution of Namalycastis, and suggesting ecological importance for stream benthic trophic dynamics throughout the Hawaiian archipelago

Morphological Characteristics and Species Separation of Hawaiian Postlarval Amphidromous Fishes

There are five Hawaiian amphidromous fishes (Gobiidae: Lentipes concolor, Awaous guamensis, Sicyopterus stimpsoni, Stenogobius hawaiiensis; Eleotridae: Eleotris sandwicensis). Amphidromous adults deposit eggs on the stream bottom. After hatching, larvae drift to the ocean for growth followed by postlarval migration back into the streams. Postlarvae were collected to construct a dichotomous identification key based on 12 morphological measures and ray counts from four fins. Overall, the presense of fused pelvic fins, standard length (SL), and fin ray numbers were the most useful in species separation. Gobies were separated from the eleotrid by the former having fused pelvic fins. Within the gobies, S. stimpsoni had the largest SL [mean (SD) = 20.5 (1.0) mm] with A. guamensis [15.8 (0.6)mm] smaller and L. concolor [13.7 (1.3) mm] and S. hawaiiensis [13.3 (1.0) mm] the smallest. Although SL alone could not separate L. concolor and S. hawaiiensis, the former had 5 first dorsal fin rays compared to 6 in all other gobies. Nineteen pectoral fin rays separated S. stimpsoni from A. guamensis, and SL along with anal and second dorsal fin ray number, separated A. guamensis from S. hawaiiensis. Canonical discriminate function analysis was used as an exploratory approach to confirm the dichotomous key. With all morphological features entered into the analysis, three significant discriminate functions were generated with the most highly correlated morphological variables within each function the same as those used in the dichotomous key. Additionally, regression models were generated for predicting SL from total length (TL) of three postlarval species. Measures of TL do not require excessive handling or killing specimens; however, SL is usually the preferred measure for body size. The ability to identify migrating postlarvae under a variety of conditions aids in data acquisition under circumstances where preservation may or may not be necessary for the research objectives

Temporal changes in temperature may suggest microhabitat shifts in larval spongillafly Climacia areolaris Hagen (Neuroptera: Sisyridae) abundance and density in a temperate freshwater lake

Abiotic factors such as temperature and depth are known to affect aquatic insect populations and are thought to be major variables that directly impact how communities are assembled and populations distributed. The purpose of this study was to examine the role of temperature and depth in structuring C. areolaris populations within a temperate freshwater quarry. Larval densities among individual sponges at different depths were determined over six months in a Pennsylvania quarry. Sponges from four depths (7.0 - 8.0 m; 8.1 - 9.0 m; 9.1 - 10.0 m and 10.1 - 12.0) were collected once per month (n = 3) using SCUBA. Temperature data were collected at four depths (n = 3 samples/depth). Larval densities significantly varied over the study period, but were not significantly different between depths on any date. Mean total larval density was significantly higher in March, April and May compared to dates later in the season. This result followed an inverse pattern where there was a significant effect of date on temperature, but no difference between depths. There was a detectable change in relative abundance of the sisyrid populations among the depths; the two shallowest depth ranges collectively represented \u3e50% of the population during March and April, but were \u3c 50% throughout the rest of the summer. There was also a significant negative relationship of larval density with temperature. Few studies have documented the role of abiotic factors such as depth and temperature on the spatial and temporal structuring of spongillafly microdistribution within a quarry environment

Life Cycle of a Torrenticolous Hawaiian Chironomid (Telmatogeton Torrenticola): Stream Flow and Microhabitat Effects

In this study we documented the instar densities and life cycle of Telmatogeton torrenticola Terry (Chironomidae : Telmatogetoninae) from Kinihapai Stream, Maui, Hawaii. Greatest larval densities of this midge are found on substrates of high velocity, shallow flows of cascades, and splash zones of waterfalls, with lower densities in riffles. In the summer of 1994 we compared the effects of two microhabitats (termed optimal and suboptimal) on inter-instar density and relative abundance. In a second year (1995), we evaluated the effect of long-term reduced stream flow on these variables only in optimal microhabitats. A significant reduction in stream flow from 1994 to 1995 was correlated with a similar reduction in larval densities that precluded larval colonization of suboptimal habitats in 1995, thereby preventing sampling in this microhabitat during that summer. Depth of optimal habitats of 1995 were significantly shallower than both habitats of 1994, with suboptimal habitats of 1994 the deepest. Total larval density was significantly higher in 1994 optimal habitats, while 1994 suboptimal and 1995 optimal habitats were statistically similar. Individual instar densities showed variable differences among habitats and years, with the first three instars always highest in 1994 optimal habitats. All instars and pupae were collected on most sampling dates in both years ; however, pupae were only collected on a two dates in suboptimal habitats of 1994. Based on larval size frequency histograms, T. torrenticola has a multivoltine, asynchronous life cycle, with continuous reproduction, which is variable among microhabitats characterized by different flow velocity and depth, and between years of differing stream discharge. Reduced stream flow during the summer of 1995 had effects of reducing densities and changing life cycle features similar to those found in 1994 (a year of higher stream flow) suboptimal habitats

The Occurrence of the Freshwater Clams, Musculium partumeium (Say) and Pisidium casertanum (Poli) (Bivalvia: Sphaeriidae), in the Hawaiian Islands

Sphaeriid clams were collected from an ancient, continuously cultivated taro pond complex at Ke‘anae Peninsula, Maui. Both species are known for adaptations for temporary pond habitats and could have been initially introduced by the earliest Hawaiian settlers transported with moist taro root stock from other areas of Oceania

A Note on Cascade Climbing of Migrating Goby and Shrimp Postlarvae in Two Maui Streams

In this study, we documented cascade climbing rates of 133 and 230 postlarvae of Lentipes concolor (O‘opu alamo‘o) and Atyoida bisulcata (Opae kahaole), respectively, from two streams on the island of Maui, Hawaii. Climbing measurements and observations were made of postlarvae at the water-substrate interface in cascade habitats of constricted water flow. Both species were observed to move in short bursts of forward progression within or above the pulsing water-substrate interface. Goby postlarval climbing rates ranged from 0.04 – 1.50 cm s–1 and were slower than shrimp rates which ranged from 0.30 – 3.06 cm s–1. The high variability is attributed to the bursting movement behaviors exhibited by both species. During one night of monitoring, a mean of 9.4 shrimp min–1 were observed to climb along ~ 0.4 m stretch of the watersubstrate interface, resulting in conservative recruitment estimate of 564 shrimp h–1. Potential applications to stream management are discussed

Carcasses at Fixed Locations Host a Higher Diversity of Necrophilous Beetles

In contrast to other necro mass, such as leaves, deadwood, or dung, the drivers of insect biodiversity on carcasses are still incompletely understood. For vertebrate scavengers, a richer community was shown for randomly placed carcasses, due to lower competition. Here we tested if scavenging beetles similarly show a higher diversity at randomly placed carcasses compared to easily manageable fixed places. We sampled 12,879 individuals and 92 species of scavenging beetles attracted to 17 randomly and 12 at fixed places exposed and decomposing carcasses of red deer, roe deer, and red foxes compared to control sites in a low range mountain forest. We used rarefaction-extrapolation curves along the Hill-series to weight diversity from rare to dominant species and indicator species analysis to identify differences between placement types, the decay stage, and carrion species. Beetle diversity decreased from fixed to random locations, becoming increasingly pronounced with weighting of dominant species. In addition, we found only two indicator species for exposure location type, both representative of fixed placement locations and both red listed species, namely Omosita depressa and Necrobia violacea. Furthermore, we identified three indicator species of Staphylinidae (Philonthus marginatus and Oxytelus laqueatus) and Scarabaeidae (Melinopterus prodromus) for larger carrion and one geotrupid species Anoplotrupes stercorosus for advanced decomposition stages. Our study shows that necrophilous insect diversity patterns on carcasses over decomposition follow different mechanisms than those of vertebrate scavengers with permanently established carrion islands as important habitats for a diverse and threatened insect fauna.publishedVersio

Temporal and Spatial Impact of Human Cadaver Decomposition on Soil Bacterial and Arthropod Community Structure and Function

As vertebrate carrion decomposes, there is a release of nutrient-rich fluids into theunderlying soil, which can impact associated biological community structure andfunction. How these changes alter soil biogeochemical cycles is relatively unknown and may prove useful in the identification of carrion decomposition islands that have long lasting, focal ecological effects. This study investigated the spatial (0, 1, and 5 m) and temporal (3–732 days) dynamics of human cadaver decomposition on soil bacterial and arthropod community structure and microbial function. We observed strong evidence of a predictable response to cadaver decomposition that varies over space for soil bacterial and arthropod community structure, carbon (C) mineralization and microbial substrate utilization patterns. In the presence of a cadaver (i.e., 0 m samples), the relative abundance of Bacteroidetes and Firmicutes was greater, while the relative abundance of Acidobacteria, Chloroflexi, Gemmatimonadetes, and Verrucomicrobia was lower when compared to samples at 1 and 5 m. Micro-arthropods were more abundant (15 to 17-fold) in soils collected at 0 m compared to either 1 or 5 m, but overall, micro-arthropod community composition was unrelated to either bacterial community composition or function. Bacterial community structure and microbial function also exhibited temporal relationships, whereas arthropod community structure did not. Cumulative precipitation was more effective in predicting temporal variations in bacterial abundance and microbial activity than accumulated degree days. In the presence of the cadaver (i.e., 0 m samples), the relative abundance of Actinobacteria increased significantly with cumulative precipitation. Furthermore, soil bacterial communities and C mineralization were sensitive to the introduction of human cadavers as they diverged from baseline levels and did not recover completely in approximately 2 years. These data are valuable for understanding ecosystem function surrounding carrion decomposition islands and can be applicable to environmental bio-monitoring and forensic sciences

Buruli ulcer disease prevalence in Benin, West Africa: associations with land use/cover and the identification of disease clusters

© 2008 Wagner et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution Licens

Bacterial Community Succession, Transmigration, and Differential Gene Transcription in a Controlled Vertebrate Decomposition Model

Decomposing remains are a nutrient-rich ecosystem undergoing constant change due to cell breakdown and abiotic fluxes, such as pH level and oxygen availability. These environmental fluxes affect bacterial communities who respond in a predictive manner associated with the time since organismal death, or the postmortem interval (PMI). Profiles of microbial taxonomic turnover and transmigration are currently being studied in decomposition ecology, and in the field of forensic microbiology as indicators of the PMI. We monitored bacterial community structural and functional changes taking place during decomposition of the intestines, bone marrow, lungs, and heart in a highly controlled murine model. We found that organs presumed to be sterile during life are colonized by Clostridium during later decomposition as the fluids from internal organs begin to emulsify within the body cavity. During colonization of previously sterile sites, gene transcripts for multiple metabolism pathways were highly abundant, while transcripts associated with stress response and dormancy increased as decomposition progressed. We found our model strengthens known bacterial taxonomic succession data after host death. This study is one of the first to provide data of expressed bacterial community genes, alongside transmigration and structural changes of microbial species during laboratory controlled vertebrate decomposition. This is an important dataset for studying the effects of the environment on bacterial communities in an effort to determine which bacterial species and which bacterial functional pathways, such as amino acid metabolism, provide key changes during stages of decomposition that relate to the PMI. Finding unique PMI species or functions can be useful for determining time since death in forensic investigations