Michael D. Kaller

Evidence of a threshold level of fine sediment accumulation for altering benthic macroinvertebrate communities

When land use practices alter natural hydrologic and sediment delivery regimes, the effects usually are negative to macroinvertebrates. We hypothesized a threshold level of fine sediment accumulation in the substrate may exist where benthic macroinvertebrate abundance and diversity will be significantly reduced. We surveyed seven Appalachian streams with different levels of substrate fine sediment twice yearly from fall 1998 to spring 2000. Three riffles (with 2 replicates each) were sampled with a 0.25 mm Surber sampler in each season and stream. Simple linear regression was used to test relationships between substrate size classes and metrics, and nested ANOVA was used to test macroinvertebrate differences among streams. Consistent negative relationships with the finest substrate particles (<0.25 mm) were observed with EPT (Ephemeroptera, Plecoptera, and Trichoptera) taxa richness. In seasons of normal hydrology, EPT taxa richness significantly decreased (p<0.05) in streams where fine substrate particles (<0.25 mm) exceeded 0.8–0.9% of riffle substrate composition. In drought seasons, fine sediment (<0.25 mm) exceeded 0.8–0.9% in most surveyed streams, lowering macroinvertebrate diversity in all streams. In these streams, a threshold for EPT diversity appears to be in excess of 0.8–0.9% fine sediment (<0.25 mm) substrate accumulation. We suggest similar threshold levels exist in other streams where macroinvertebrate taxa are altered with potential effects on trophic webs and nutrient processing.

How much do valley fills influence headwater streams

AbstractValley fill mining has the potential to alter headwater stream habitat in many areas in the eastern United States. In valley fill mining, overburden is removed to expose underlying coal seams. The overburden is then deposited in the adjacent valley. The deposited overburden from mining increases sedimentation, increases stream conductivity, and alters hydrologic regimes downstream of the fill. Changes in downstream communities are not well documented. However, it was suspected the increased sedimentation and conductivity would have deleterious effects upon the downstream macroinvertebrate communities. In southern West Virginia, four pairs of streams, each consisting of a fill and a reference stream, were selected as representative of watersheds experiencing valley fill mining. Stream pairs were selected for similar environmental conditions, with one stream having a valley fill in its headwaters. Each stream was sampled by replicate Surber samples (n=9 per stream). Water chemistry and sediment measurements also were taken at each location. Valley fill streams experienced significantly higher specific conductance (p < 0.01), but did not have elevated levels of fine sediment. Fills exhibited elevated levels of Na, K, Mn, Mg, Ca, Ni and Fe relative to reference streams. Additionally, valley fill streams demonstrated significantly lower densities of Ephemeroptera, Coleoptera, Odonata, Non-insects, Scrapers, and Shredders (p < 0.03) than reference streams. Further, Ephemeroptera richness was negatively related to specific conductivity and many of the richness metrics were negatively related to metals, both of which were generally elevated in fill streams. It appears that at the minimum, valley fills increase specific conductance and metals in streams and this or some other unqualified factors structure the macroinvertebrate community downstream of the valley fill. However, given the level of disturbance in valley fills, it is surprising how little differences existed between fills and reference stream biota.

Swine Activity Alters Invertebrate and Microbial Communities in a Coastal Plain Watershed

Abstract Swine (Sus scrofa Linnaeus) are an invasive species with a negative impact on native terrestrial plant and animal diversity. Further, in its native range, excessive population size has been perceived as a potential problem. The effects of swine on aquatic organisms remain poorly documented. We investigated the effect of an unmanaged population of feral and free ranging swine upon aquatic habitat, invertebrates and microbes in a coastal plain stream in Louisiana. Sampling was conducted twice yearly, spring and fall, from August 2002 through April 2004, at five sites within the Mill Creek watershed. We measured stream characteristics, carbon and nitrogen, biochemical oxygen demand, fecal coliform counts and heterotrophic plate counts. We collected invertebrates from woody debris, microbes from the water column and identified both to the lowest practical taxon. Invertebrate, microbial, habitat and swine relationships were assessed with detrended and canonical correspondence analysis. Swine activity did not appear to alter stream habitats. However, swine changed the microbial taxonomic composition in the stream increasing pathogens. Swine also appeared to have a positive relationship with gastropods (snails) and a negative relationship with collecting and scraping (predominantly insect) taxa in the streams. We suggest the decline of scraper taxa may be related to the changes in microbial composition. Shifts in the invertebrate community can impact other organisms in the ecosystem, and the full extent of swine impacts on other aquatic organisms may also be negative.

Evaluation of target strength–fish length equation choices for estimating estuarine fish biomass

In the Gulf of Mexico (GOM), fish biomass estimates are necessary for the evaluation of habitat use and function following the mandate for ecosystem-based fisheries management in the recently reauthorized Sustainable Fisheries Act of 2007. Acoustic surveys have emerged as a potential tool to estimate fish biomass in shallow-water estuaries, however, the transformation of acoustic data into an index of fish biomass is not straightforward. In this article, we examine the consequences of equation selection for target strength (TS) to fish length relationships on potential error generation in hydroacoustic fish biomass estimates. We applied structural equation models (SEMs) to evaluate how our choice of an acoustic TS–fish length equation affected our biomass estimates, and how error occurred and propagated during this process. To demonstrate the magnitude of the error when applied to field data, we used SEMs on normally distributed simulated data to better understand the sources of error involved with converting acoustic data to fish biomass. As such, we describe where, and to what magnitude, error propagates when estimating fish biomass. Estimates of fish lengths were affected by measurement errors of TS, and from inexact relationships between fish length and TS. Differences in parameter estimates resulted in significant differences in fish biomass estimates and led to the conclusion that in the absence of known TS–fish length relationships, Love’s (J Acoust Soc Am 46:746–752, 1969) lateral-aspect equation may be an acceptable substitute for an ecosystem-specific TS–fish length relationship. Based upon SEMs applied to simulated data, perhaps the most important, yet most variable, component is the mean volume backscattering strength, which significantly inflated biomass errors in approximately 10% of the cases.

Bird Community Response to Vegetation Cover and Composition in Riparian Habitats Dominated by Russian Olive (Elaeagnus angustifolia)

Abstract Riparian systems in the western United States provide important habitat for bird communities during all times of the year. In recent decades, invasive plants, such as Russian olive (Elaeagnus angustifolia), have achieved broad distribution and local dominance in many western riparian areas, raising concerns over the loss of ecological function within these systems. In 2005 and 2006 we conducted avian point counts and surveyed vegetation cover at 95 points along the Snake and Columbia Rivers in southeastern Washington to investigate the effects of total woody vegetation cover and the relative proportion of Russian olive cover on breeding and wintering riparian bird communities. Our results indicated that riparian habitats dominated by Russian olive can support diverse and abundant bird communities, though cavity nesting species were noticeably sparse. Bird density and species richness were best explained by a quadratic relationship to total woody vegetation cover in both seasons, as was breeding bird community composition, with greatest density and richness in intermediate cover levels. We found no indication that the proportion of the woody vegetation comprised of Russian olive strongly influenced any of these bird community metrics. Given that Russian olive comprised 81.6% of the riparian vegetation in our study area, it is unclear from our results how Russian olive would affect bird communities in regions where native vegetation is more abundant. Regardless, complete eradication of Russian olive from riparian systems where the plant is a major component will reduce the overall habitat value for birds by eliminating significant structural complexity.

Basins for Fish and Ecoregions for Macroinvertebrates: Different Spatial Scales Are Needed to Assess Louisiana Wadeable Streams

Abstract We targeted wadeable streams in six USEPA Level III ecoregions spanning eight major study basins in northern Gulf of Mexico coastal plains and terraces to identify appropriate spatial frameworks for the assessment of stream quality, as well as fish species and macroinvertebrate families that were characteristic of least disturbed conditions. We analyzed previously collected (1990–2006) and recently collected (2005–2010) stream fish and macroinvertebrate data with mean similarity analysis to identify spatial frameworks, either basins or ecoregions, appropriate for the assessment of stream fish and macroinvertebrates. We also conducted partial redundancy analysis of fish and macroinvertebrates separately, controlling for differences in stream size, and variance partitioning to identify the variation attributable to ecoregion or basin as a measure of the importance of spatial influence. Our results indicated that fish distributions were better described by basins, with anticipated strong dissimilari...

Likely Changes in Habitat Quality for Fish and Wildlife in Coastal Louisiana during the Next Fifty Years

ABSTRACT Nyman, J.A.; Baltz, D.M.; Kaller, M.D.; Leberg, P.L.; Parsons Richards, C.; Romaire, R.P., and Soniat, T.M., 2013. Likely changes in habitat quality for fish and wildlife in coastal Louisiana during the next fifty years. Louisianas 2012 Master Plan for a sustainable coast was designed to minimize economic damage from storm surges and to maximize wetland habitat for fish and wildlife. Selecting projects for inclusion in the master plan depended partly on models that simulated the effects of management options on environmental factors that control habitat quality for fish and wildlife. We used 13 models to predict the effects of the master plan on habitat quality for fish and wildlife in coastal Louisiana. Habitat quality was predicted to change more for the Neotropical songbirds and seven other modeled species losing habitat quality with the status quo (−37%) than it was predicted to increase for five modeled species gaining habitat quality with the status quo (+18%). The master plan was predicted to slow or negate all changes associated with the status quo. All of the modeled fish and wildlife belong to people of the state of Louisiana, people living in countries bordering the Gulf of Mexico, and to people throughout the Americas. Thus, declining fish and wildlife habitat quality in Louisiana probably will cause market and nonmarket losses, which although concentrated in Louisiana, will extend across the Americas. As funding for Louisianas master plan is pursued, it is important to consider that almost all of the causes for net wetland losses in Louisiana are external to the owners of these wetlands but that the fish and wildlife that use these wetlands belong to and benefit people throughout the Americas.

Effects of Hurricanes Katrina and Rita on Sport Fish Community Abundance in the Eastern Atchafalaya River Basin, Louisiana

Abstract The Atchafalaya River basin (ARB), a 5,000-km2 river–floodplain system in south-central Louisiana, provides one of the most popular fisheries in the state for anglers pursuing bass Micropterus spp., sunfishes Lepomis spp., crappies Pomoxis spp., and catfishes Ictalurus spp. Hurricanes Katrina and Rita struck in August and September 2005, resulting in tremendous changes in habitat and water quality in the ARB. Although the short-term and long-term impacts of these storms on this floodplain ecosystem remain poorly understood, a long-term fish and water quality monitoring program has provided data with which to analyze sport fish abundance in the eastern ARB 2 years before and 2 years after the hurricanes. The results of this analysis suggest that location within the basin influenced the effect of the hurricanes on sport fish abundance and that overall sport fish catch per unit effort (CPUE) decreased after the hurricanes. Within the study area, sunfishes in Bayou Postillion, bass and sunfishes in M...

EFFECTS OF A SMALL-SCALE CLEARING ON HABITAT AND MACROINVERTEBRATES OF A COASTAL BOTTOMLAND STREAM IN LOUISIANA

Abstract Streams in the southeastern USA are commonly affected by streamside disturbance. We investigated the effects of a small-scale clearing (associated with a pipeline crossing) on a third-order stream in southwestern Louisiana by sampling habitat, water chemistry, stream microbes, and benthic and wood-dwelling macroinvertebrates in fall 2002 and spring 2003. We selected 3 locations for sampling, one in a forested section of stream 100 m upstream of a clearing, one within the clearing, and one in a forested section of stream 100 m downstream from the clearing. We detected significantly higher temperature and fecal coliform counts and significantly lower dissolved oxygen, specific conductance, pool-riffle ratio, coarse woody debris, fine organic detritus, and heterotrophic plate counts in the clearing location compared to the upstream and downstream locations. Depth and current velocity did not differ significantly among sampling locations. Despite differences in stream characteristics, we detected only a single statistical difference: Bezzia (Insecta: Diptera: Ceratopogonidae) was significantly lower in density in the clearing location. We conclude that the observed differences in stream characteristics were not biologically substantial enough to noticeably alter composition of the stream macroinvertebrate community. However, multiple small-scale disturbances that increase fragmentation in a watershed would be more likely have significant negative affects on macroinvertebrate community diversity.

Occurrence of Freshwater Bivalves in a Chronically Hypoxic Coastal Stream in Louisiana, USA

ABSTRACT We sampled bivalves in Mill Creek, a low-gradient stream in southwestern Louisiana, and found a comparatively diverse assemblage in a disturbed, chronically hypoxic stream. We found few bivalves in April, nearly 1,700 in June, but only 170 in September. Species richness varied temporally with one species in April, eight species in June, and three species in September. We suggest dissolved oxygen level plays a particularly important role in bivalve community dynamics in this stream.