Density Of Aquatic Invertebrates Research Articles

Response of benthic macroinvertebrate assemblages to round (Neogobius melanostomus, Pallas 1814) and tubenose (Proterorhinus semilunaris, Heckel 1837) goby predation pressure

One of the main assumed impacts of invasive gobies is predation on benthic macroinvertebrates. Despite numerous dietary studies, however, quantitative evaluations of impact in European river systems are scarce. Here, we investigate the impact of tubenose (Proterorhinus semilunaris, Heckel 1837) and round (Neogobius melanostomus, Pallas 1814) gobies on macroinvertebrates in a lowland river (River Dyje, Czech Republic) by allowing and preventing gobiid access to rip-rap substrate naturally colonised by invertebrates at two sites (Site 1—tubenose goby only, Site 2—tubenose and round gobies). Gobies had a negative impact on invertebrates at both sites, with overall invertebrate density reduced by 15% (ca. 17.9 g m−2 per year) at Site 1 and 36% (ca. 23.6 g m−2 per year) at Site 2. Both species showed increased impact in summer and ingested larger invertebrates preferentially, resulting in an overall reduction in invertebrate body size. Tubenose gobies had a significant impact on Annelida, Gastropoda, Crustacea and Ephemeroptera nymphs, while tubenose and round goby together impacted Annelida, Bivalvia (Dreissena), Gastropoda, Crustacea, Ephemeroptera nymphs, Odonata nymphs and Chironomidae larvae. Our results confirm that round and tubenose gobies can have a significant negative impact on aquatic invertebrate density and community composition.

Aquatic invertebrate production in moist-soil managed wetlands on Richland Creek Wildlife Management Area, east-central Texas

Abstract Aquatic invertebrates have significant value to wetland-dependent species as well as to wetlands themselves. They process organic matter through producer and detritus food webs, modify wetland habitats, and provide a food resource to wetland-dependent species such as waterfowl and shorebirds. Timely flooding and drawdown of water within moist-soil managed wetlands will increase invertebrate diversity and abundance, allowing wetland managers to maximize the production of such areas. We examined how flood timing and duration influenced aquatic invertebrate density, diversity, richness, and production within four moist-soil managed wetlands on Richland Creek Wildlife Management Area, east-central Texas from January 2004 through December 2006. A total of 12,089 aquatic invertebrates from 41 aquatic invertebrate families were collected. Overall, diversity indices were 0.76 (Simpson's Index) and 2.47 (Shannon-Wiener Index). Most common aquatic invertebrates were Crustacea (n = 3,568) and Ephemeroptera ...

Characterizing Biodiversity of Alpine Streams in Grand Teton National Park, Wyoming

The highest rate of climate change is occurring in alpine areas above permanent treeline. The Teton Mountains in northwestern Wyoming are one of these ecosystem and little work has been done on alpine streams in the area. We sampled 6 streams in the Teton Mountains in 2015 at both upper and lower sites. We measured environmental variables (e.g., glacierality index, basic water quality, and temperature), aquatic invertebrate assemblages and microbial diversity. The water sources for sampled streams were glacier-fed, snowmelt and icy-seep. Aquatic invertebrate density (116-11,523 ind/m2) and biomass (31-21,704 mg/m2) varied greatly among streams. Snowmelt streams had the highest biomass of invertebrates, but the density and richness did not differ among stream types. Micrbial diversity in groundwater-fed springs harbored higher diversity than glacier-fed streams. The discovery of an icy-seep stream type lead us to sample rock glacier in the Teton Mountains during 2016. We hope to continue to sample alpine streams in the Teton Mountains to understand how climate change will alter streams of different types.

Comparing Stream Invertebrate Assemblages Before and After Wildfire in Yellowstone National Park

Warmer, dryer climate conditions during the past 3 decades are thought to have increased severe fires in the western United States. Severe fires may change food webs due to altered light levels, nutrient concentrations, and hydrology in streams. To measure how wildfire changes stream food webs, we collected aquatic invertebrates before and after a fire, and calculated their density. To investigate the effects of wildfire on streams, we collected aquatic invertebrates from Cub Creek on the east side of Yellowstone Lake before and after the East Fire. The timing of our study was serendipitous with the fire burning after our first year of collecting samples. Therefore, we collected one year of data prior to the wildfire (2003) and 2 years of data after the fire (2004 and 2005). The East Fire was a crown fire that set ablaze >9000 hectares and burned 95% of the watershed of this stream. Working in Yellowstone National Park is opportune, because few other perturbations exist and the effects of wildfire can be easily studied. We analyzed the samples to understand how wildfire alters stream invertebrates. Our specific questions are: 1.) What effect did wildfire have on the density of aquatic invertebrates? 2.) How did the composition of aquatic invertebrates change before and after wildfire? Results from our study will inform managers about how the food base for fish (i.e., aquatic invertebrates) changes after wildfire.

Periphyton and invertebrate response to wood placement in large pacific coastal rivers

AbstractWood abundance in aquatic systems has been dramatically reduced compared to historical levels due to anthropogenic activities that led to wood removal and stream simplification. As a result, reintroduction of wood to aquatic systems is now a widely used and relatively well‐studied restoration technique for increasing habitat complexity. Although stream periphyton (biofilm) and invertebrates serve as food sources for a variety of predators including fish, birds and bats, data on how lower trophic levels respond to wood placement are relatively scarce. The purpose of this study was to test the hypothesis that periphyton biomass and aquatic invertebrate density were higher on Engineered Log Jams (ELJs) than on inorganic substrates in two large Pacific Northwest river systems. Among years and rivers, periphyton biomass and invertebrate densities were significantly higher on ELJs than on cobbles within the same reach. Invertebrate communities on ELJs were dominated by meiofauna (<500 µm), whereas cobbles were dominated by larger chironomids. We attribute these trophic level differences to substrate type, as we did not detect taxonomic differences between cobbles in reaches with and without ELJs. We show that adding wood to reaches with little or no naturally occurring wood increased overall habitat surface area and thereby the potential for increased productivity relative to reaches with low levels of wood. Finally, wood supports a unique community of invertebrates that are often overlooked in lotic system studies but may be contributing substantially to overall biological diversity. Published in 2009 by John Wiley & Sons, Ltd.

Decomposition Rate and Community Structure of Leaf-packs in an Urban and Rural Stream in Southwestern Missouri

Previous studies demonstrated significantly lower diversity and density of aquatic invertebrates in a southwestern Missouri urban stream, Turkey Creek, below a large mall in comparison to above mall sites and a rural stream, Jones Creek. Such invertebrate declines might affect leaf decomposition rates in these streams. We estimated decomposition rate and macro-invertebrate community structure using experimental leaf-packs composed of freshly dried red elm leaves. Thirty-six leaf-packs housed in polyester mesh (2 by 4 mm) bags were anchored in riffles at the three sites. Bags were recovered after 15 and 36 days, invertebrates were removed and identified, and leaf residue air dried. Decay rates as fraction lost/day after 15 days were 4.20%/day Turkey Creek above mall, 4.43%/day Turkey Creek below mall, and 4.45%/day at Jones Creek. After 36 days decay rates were 2.14%/day Turkey Creek above mall, 2.15% Turkey Creek below mall, and 2.36%/day Jones Creek. Rates were not significantly different between sites (ANOVA, P = 0.55 at 15 days and P = 0.23 at 36 days). Decay constants calculated by regressing % dry mass remaining and days in stream were −0.040/day for both Turkey Creek above and below mall and −0.056/day for Jones Creek. Shredders were primarily represented by the cranefly larvae Tipula abdominalis in both TC sites and by T abdominalis and the isopod Lirceus hoppinae in JC. Collector-gatherers, primarily net-spinning caddisflies Cheumatopsyche, Ceratopsyche, and Chimarra, as well as the dipteran family Chironomidae, numerically dominated leaf-packs. Leaf decomposition may be more related other factors, physical fragmentation, microbial processes, and seasonal differences in leaf abundance, than shredding in these streams. Dominance of collector-gatherers appears to indicate leaf-packs serve primarily as habitat and not a direct energy source for many stream macroinvertebrates.

Lateral organization of aquatic invertebrates along the corridor of a braided floodplain river

Although spatial scale, upstream–downstream gradients, environmental variability, and floodplain connectivity and complexity have been recognized as integral components of our understanding of riverine pattern and process, aquatic invertebrate community structure across lateral gradients from headwaters to the lowland of a river has received little empirical documentation. Aquatic invertebrate density, distribution, and richness were investigated at 29 study sites distributed laterally (main channel–floodplain) among 6 geomorphologically distinct river reaches from the headwaters to near the mouth of one of the last seminatural river corridors draining the European Alps, the Tagliamento River in northeastern Italy. Community relationships were examined using multivariate and diversity analyses to investigate patterns of taxonomic richness. Diversity parameters were scaled at the site, reach, and catchment levels to better understand local and regional patterns. Mean invertebrate density increased from 7484 ± 2480 (±1 SE) individuals/m2 in the headwaters to 98,811 ± 18,037 individuals/m2 on the lowland floodplain. Crustacea, Coleoptera, and Ephemeroptera richness increased and nonchironomid Diptera and Plecoptera richness declined along the corridor. Richness (α diversity) and turnover (β diversity) showed no consistent increase or decrease along connectivity gradients within geomorphic reaches along the river corridor, possibly because each reach had unique characteristics. α diversity was similar among geomorphic reaches along the corridor, whereas β diversity between reaches increased as a function of distance between them. Direct gradient analysis indicated high taxa-to-environment concordance along lateral (i.e., floodplain water bodies) and longitudinal (upstream–downstream) dimensions and indicated distinct floodplain communities. These results demonstrate how lateral gradients (floodplain dimension) structure zoobenthic communities and how this structure can change along the longitudinal dimension (upstream–downstream). Our results highlight the importance of off-channel environments to macroinvertebrate community structure and diversity. Conservation, restoration, and preservation measures must consider the lateral dimension along river corridors as integral to maintaining diversity and community structure.

Breeding density of Dippers Cinclus cinclus‘ Grey Wagtails Motacilla cinerea and Common Sandpipers Actitis hypoleucos in relation to the acidity of streams in south‐west Scotland

The distribution of breeding pairs of Dippers Cinclus cinclus, Grey Wagtails Motacilla cinerea and Common Sandpipers Actitis hypoleucos was assessed along 18 streams in south‐west Scotland during summer 1987, and the lengths of territories, occupied by 5 5 breeding pairs of Dippers, were measured. In each stream the water chemistry, physical structure (e.g. gradient, altitude, nature of bankside vegetation) and density of aquatic invertebrates was determined. The density of breeding pairs of dippers was significantly lower along streams of low pH (high acidity) and steep gradients, and territories were significantly longer at these sites compared with those of higher pH. Many of the invertebrate families that are important prey for Dippers were scarce at sites of low pH, particularly caddisfly larvae (Trichoptera) and mayfly nymphs (Ephemeroptera). The low numbers and large territories of breeding pairs of Dippers on acidic streams may be due to reduced density and diversity of macroinvertebrate prey. Stream pH was not an important correlate of the distribution or density of Grey Wagtails or Common Sandpipers. It is suggested that the lack of any similar effect of pH on these other two species compared with Dippers is attributable to differences in their feeding ecology.

Response of aquatic macroinvertebrates to early-spring drawdown in nodding smartweed marshes

Effects of early-spring water-level reduction on aquatic macroinvertebrate populations were studied in four nodding smartweed (Polygonum lapathifolium L.) marshes in northwest Ohio. Water depths in two marshes were maintained at normal (>40 cm) overwinter levels then were reduced in early April each year to approximately 50% (20 cm) of over-winter depth. Water levels in two other marshes were allowed to fluctuate naturally throughout the study period. Aquatic invertebrate density and biomass were sampled from late March through mid-Junc in the water column, in the benthos, and on the surfaces of nodding smartweed plants. Invertebrate levels (activity, density, and biomass) in the water column were higher (P<0.05) in shallow marshes than in deep marshes. Benthic invertebrate levels in all marshes were low compared to invertebrate levels in the water column. Water-level reduction in smartweed marshes did not significantly increase benthic or periphytic invertebrate levels in shallow marshes over those in deep marshes.