Habitat-specific effects of interstitial space between stream substrate particles on the colonization of aquatic organisms

We examined the effects of interstitial space between stream substrate particles on the colonization of aquatic organisms using three types of substrates (gravel, a cobble, and a cobble on gravel) in a riffle and pool of a temperate stream. Significantly greater abundance, wet weight, diversity (H′), taxonomic richness, and evenness of aquatic organisms were found in the riffle than in the pool, and the interstitial space substrate (i.e., a cobble on gravel) had significantly greater abundance, wet weight, and taxonomic richness of aquatic organisms than did the cobble substrate. Of the 13 families observed in the experiments, larval net-spinning caddisfly (Hydropsychidae) dominated the riffle in terms of the abundance and wet weight; chironomid larvae dominated both the riffle and the pool in terms of abundance. Simple main effect tests indicated significant effects of substrate on the abundance and wet weight of larval caddisfly in the riffle, and post hoc tests on substrate in each habitat indicated that the abundance and wet weight of larval caddisfly on interstitial space substrate were significantly greater than those on cobble substrate in the riffle. Our results suggest the importance of interstitial space between stream substrates in riffles to ensure higher colonization rates of aquatic organisms such as larval net-spinning caddisflies characterized as filter feeders.

Visual Impacts of Stalk Forming Diatoms in Grand Teton National Park

A survey was conducted in August 2008 to determine the distribution and extent of stalked diatoms in major rivers and streams in Grand Teton National Park (GTNP). We determined that a nuisance bloom of the diatom Didymosphenia geminata was present in Lake Creek from the outlet of Phelps Lake to approximately 1 km downstream of the Rockefeller Preserve. This bloom was considered "excessive" because the coverage of the stream substrate was 70% or above for greater than 1 km. This diatom species is able to survive out of water in damp conditions, and it may be transported on the gear of recreationalists. In GTNP, this diatom was found in a high visitor use area, with concomitant potential for the species to be spread by anglers to other sites within the national park. Although there are several factors that appear to influence its distribution, recent nuisance blooms of this species suggest popular angling sites are often sites of nuisance blooms. Decontamination of aquatic gear by recreationalists may be appropriate to limit the spread of nuisance blooms within the national park system and adjacent public and private water bodies

Is "Rocksnot" (Didymosphenia Geminata) in Grand Teton National Park?

Didymosphenia geminata is a microscopic single-celled freshwater diatom. The invasive behavior of D. geminata is greatly altering physical and biological conditions in streams and rivers; the stalk material byproduct that D. geminata produces has the potential to cover up to 100% of stream substrate with a thickness of 20 cm. Even though D. geminata is native to the United States, it is acting like an invasive species. Once only identified in nutrient poor waters, D. geminata has been expanding its native range and is occurring more frequently in nutrient-rich streams and rivers. We conducted a survey of D. geminata in Grand Teton National Park Wyoming and to our knowledge, this is one of the first surveys examining D. geminata in this area. We found and confirmed D. geminata in approximately 7 streams including; Phelps Lake Outlet 1.5x108 cells/m2, Taggert Lake Outlet 2.4x107 cells/m2, Phelps Lake Inlet 2.1 x 106 cells/m2, Jenny Lake Outlet 8.4x105 cells/m2, Flat Creek 2.9x107 cells/m2, Leigh Lake Outlet 1.3x104 cells/m2, and Fish Creek 9.2x105 cells/m2. Potential commonalities in the sites where D. geminata was found and confirmed in Grand Teton National Park include lake outlet streams and high traffic areas.

The response of a small stream in the Lesni potok forested catchment, central Czech Republic, to a short-term in-stream acidification

Lesni Potok stream drains a forested headwater catchment in the central Czech Republic. It was artificially acidified with hydrochloric acid (HC1) for four hours to assess the role of stream substrate in acid-neutralisation and recovery. The pH was lowered from 4.7 to 3.2. Desorption of Ca and Mg and desorption or solution of Al dominated acid-neutralisation; Al mobilisation was more important later. The stream substrate released 4,542 meq Ca, 1,184 meq Mg, and 2,329 meq Al over a 45 m long and 1 m wide stream segment; smaller amounts of Be, Cd, Fe, and Mn were released. Adsorption of SO42- and desorption of F‾ occurred during the acidification phase of the experiment. The exchange reactions were rapidly reversible for Ca, Mg and SO42-; but not symmetric as the substrate resorbed 1083, 790 and 0 meq Ca, Mg, and Al, respectively, in a 4-hour recovery period. Desorption of SO42-; occurred during the resorption of Ca and Mg. These exchange and dissolution reactions delay acidification, diminish the pH depression and retard recovery from episodic acidification. The behaviour of the stream substrate-water interaction resembles that for soil–soil water interactions. A mathematical dynamic mass-balance based model, MASS (Modelling Acidification of Stream pediments), was developed which simulates the adsorption and desorption of base cations during the experiment and was successfully calibrated to the experimental data. Keywords: Al, Ca, Mg, base cations, acid-neutralisation, stream acidification, recovery, stream sediment, experiment, modelling, adsorption, desorption, adsorption, Czech Republic, Lesni Potok

Biases Associated with Four Stream Substrate Samplers

We compared samples collected from 10 substrates of various compositions with a single-probe freeze-core sampler, a triple-probe freeze-core sampler, a McNeil sampler, and a shovel. The accuracy with which these devices sampled particles larger than 50 mm in diameter varied; they were oversampled by the freeze-core devices, sampled in proportion to their availability by a shovel, and sampled inconsistently by the McNeil sampler. The geometric mean particle size and variance of single-probe freeze-core samples consistently exceeded those of samples collected with the other devices. Most sample means also exceeded the test substrate means. By excluding the proportions of particles larger than 50 mm in diameter in our analyses, we found that proportions of several particles sizes in samples collected by different methods differed significantly from the actual proportions in test substrates. There were few differences between the single- and triple-probe freeze-core samples or between McNeil and shovel samples. All four samplers were biased, but the McNeil sampler most frequently produced samples that approximated the true substrate composition.

Occurrence, Relative Abundance, and Size of Landlocked Sea Lamprey (Petromyzon marinus) Ammocoetes in Relation to Stream Characteristics in the Great Lakes

The effect of 14 environmental variables on the occurrence of sea lamprey (Petromyzon marinus) ammocoetes was examined in 73 tributaries of the Great Lakes. We successfully classified 86% of streams without lamprey and 90.5% of streams with ammocoete populations using discriminant analysis. Eighty percent of streams in a test data set were also successfully classified. The classification success was largely determined by differences in stream substrate characteristics based on the magnitude of canonical coefficients and contribution to the multivariate F-statistic. Streams with ammocoetes had significantly (P < 0.10) higher proportion of sand and a lower proportion of bedrock and clay than streams without ammocoetes. Catch per unit effort (CPUE) of ammocoetes collected with electro-fishing gear was also significantly related (P = 0.004) to the proportion of rubble, gravel, and clay. As well, we observed a significant (P < 0.01) positive relationship between conductivity and temperature with size of 2+ ammocoetes. Results indicate that it should be possible to develop predictions for the number of metamorphosing ammocoetes based upon differences in stream characteristics.

A comparison of bryophyte species diversity and niche structure of montane streams and stream banks

Eleven alkaline western Canadian montane streams were sampled by transects to compare the bryophyte species cover, diversity, frequency, richness, niche width, and niche overlap in three vertical zones (relative to water level) with the same parameters in four acidic streams on Slide Mountain in the Adirondack Mountains of New York. Resources for niche width and overlap include vertical distance from water surface, aspect in stream, substrate size, and percent bare substrate. Species cover, richness, and diversity increase from the submerged zone 1 (< −5 cm) to the terrestrial zone 3 (10–30 cm). Brillouin species diversity increases from 1.98 to 3.03 (means per stream) along the same gradient. All species except one from zone 1 also occur in zone 3. The niche widths for aspect in stream, substrate size, and vertical distance from water surface are all negatively correlated with their chi-square values, indicating that the width values are most reliable for small widths and become increasingly less reliable for large niche widths. Niche overlap is high among most species for at least one resource parameter.