Intermittent Headwater Streams Research Articles

Intermittent streamflow generation in a merokarst headwater catchment

Intermittent headwater streams are highly vulnerable to environmental disturbances, but effective management of these water resources requires first understanding the mechanisms that generate streamflow.

Streams dry and ecological uniqueness rise: environmental selection drives aquatic insect patterns in a stream network prone to intermittence

The study of variation of species composition among sites is key to understanding community ecology, but few studies have assessed beta diversity patterns in highly dynamic stream networks in the Neotropical region. We assessed aquatic insect patterns of local contribution to beta diversity (LCBD) and species contribution to beta diversity (SCDB) in a Neotropical drainage network composed of both perennial and intermittent streams in a dry period. We evaluated if environmental and/or spatial predictors drive patterns of LCBD. We sampled aquatic insects in 12 intermittent headwater streams and 34 perennial streams. The intermittent compared to perennial streams had higher LCBDs and lower richness. The pure environmental component significantly explained 19% of the variation of LCBD, while the pure spatial components were not significant. Forty-six taxa contributed to beta diversity above the mean of the 199 taxa. We detected the association of oxygen tolerant and good dispersal ability taxa to intermittent streams and species riffle-adapted taxa as indicators of perennial streams. We showed a disproportional contribution of intermittent streams to the regional species pool. In summary, we demonstrated that when streams dry out, compositional uniqueness may increase during the dry period making them critical to conservation planning of dynamic stream networks.

Difference in benthic invertebrate communities of headwater streams can be detected using a short elevation gradient

Communities of benthic invertebrates from a series of intermittent headwater streams spanning over a short elevation gradient (i.e., ~ 180–500 m) were investigated in April–July 2010 and May–July 2011. The main purpose of this study was to better understand whether the potential future effect of environmental change on biological communities of the Precambrian Shield’s freshwaters can be detected using elevation as a substitute for time. Since obtaining long-term environmental data is a time-consuming process, substituting space for time could instead generate similar information in a shorter time. In this study, environmental differences associated with short elevation gradient were correlated with differences in benthic invertebrate communities. Therefore, elevation gradient provides a spatial proxy for anticipated future environmental change impacts over time. It was determined that water temperature accounts for the greatest variation in communities along the elevation. Many community metrics such as abundance, functional feeding groups, diversity, and evenness were significantly different based on the difference in elevation. Result indicates that even a short elevation gradient can potentially be used as a surrogate to look at the effect of environmental change.

Effects of pulse and press drying disturbance on benthic stream communities

Natural disturbance is an integral component of most ecosystems and occurs in 3 different forms: pulse, press, and ramp. In lotic ecosystems, seasonal drought is a major form of disturbance, particularly in intermittent headwater streams, which often are reduced to pools that serve as refuges for biota. We used simulated intermittent stream pools to compare the effects of control, pulse, and press drying on growth and survival in 3 fish species (Lepomis megalotis, Campostoma anomalum, and Etheostoma spectabile) commonly found together in drought-prone streams in the Ozark Highlands, USA. We also compared effects on benthic community structure, including periphyton and chironomid density and sediment in deep (permanently watered) and shallow (intermittently dewatered) habitat. Only one species, L. megalotis, showed a significant reduction in length and mass growth in press drying compared with control treatments. Drying and type of drying had no effect on survival of any fish species. Drying and type of drying had strong overall effects on periphyton growth in shallow habitats, where ash-free dry mass decreased and the autotrophic index (the ratio of chlorophyll a to total biomass) increased significantly in drying relative to control and in press relative to pulse treatments. Drying negatively affected sediment accumulation in shallow habitat and chironomid density in deep habitat. Drying in intermittent streams has species-dependent effects on fish growth and benthic structure, and pulse and press drying differ in their effects on periphyton in these systems. These effects may have important consequences in seasonally drying streams as anthropogenic influence on stream drying increases.

Predicting alpine headwater stream intermittency: a case study in the northern Rocky Mountains

This investigation used climatic, geological, and environmental data coupled with observational stream intermittency data to predict alpine headwater stream intermittency. Prediction was made using a random forest classification model. Results showed that the most important variables in the prediction model were snowpack persistence, represented by average snow extent from March through July, mean annual mean monthly minimum temperature, and surface geology types. For stream catchments with intermittent headwater streams, snowpack, on average, persisted until early June, whereas for stream catchments with perennial headwater streams, snowpack, on average, persisted until early July. Additionally, on average, stream catchments with intermittent headwater streams were about 0.7°C warmer than stream catchments with perennial headwater streams. Finally, headwater stream catchments primarily underlain by coarse, permeable sediment are significantly more likely to have intermittent headwater streams than those primarily underlain by impermeable bedrock. Comparison of the predicted streamflow classification with observed stream status indicated a four percent classification error for first-order streams and a 21 percent classification error for all stream orders in the study area.

High Aquatic Biodiversity in an Intermittent Coastal Headwater Stream at Golden Gate National Recreation Area, California

Headwater and intermittent streams have traditionally been considered less biologically diverse than downstream perennial reaches. However, recent studies have highlighted the significant role that headwaters play in supporting regional aquatic biodiversity. Additionally, intermittent streams in the Pacific Northwest may be more diverse than similar streams in other regions. Here, we present a four-year biodiversity study of the John West Fork, an intermittent coastal headwater stream in northern California. It only flows for 5–7 months each year, but supports residual perennial pools during the summer dry season. Our goals are to describe the physical and biological settings of the John West Fork, document its aquatic biodiversity, and promote the use of it and similar streams as study systems. From 2009 to 2012, we sampled fish and invertebrates in riffles and pools during early summer (June) and in residual pools during late summer (late September/early October). We documented four vertebrate species (steelhead trout, coho salmon, California giant salamander, and Pacific chorus frog) and 159 aquatic invertebrate taxa. Steelhead trout were common each year, but coho salmon were present only in 2010 and 2011. Most invertebrate taxa were tolerant of stagnant pool conditions; only nine taxa were exclusive to flowing riffle habitats. Intermittent headwater streams similar to John West Fork are numerous along the west coast of North America. This great number of replicate systems and their tractability make them ideal for ecological studies, and their high biodiversity makes them deserving of consideration in local and regional conservation planning.

Do recolonisation processes in intermittent streams have sustained effects on benthic algal density and assemblage composition?

When intermittent streams flow, benthic algae develop from both colonising propagules and regrowing dried biofilm. We aimed to determine whether colonisation processes influence algal densities and taxonomic composition beyond the period immediately following commencement of winter flows, and whether regulation modifies those processes, in the Victoria Range, Australia. Stones were placed in two unregulated streams, and upstream and downstream of weirs in three regulated streams, after dry biofilm was removed. Epilithic algae on treatment and control stones were collected after winter flows (12 weeks). Treatment effects were still apparent in one (unregulated) stream, but not in the other streams. Algal assemblages and densities upstream and downstream of weirs differed, but there was no systematic pattern among streams. In intermittent headwater streams, recolonisation processes may influence algal assemblages until spring; but in most streams, the duration of influence will be shorter, depending on the assemblage composition in regrowth and refuges, which is also shaped by conditions during the previous flow season. If the effects of regulation depend on how idiosyncratic flow regimes and assemblage compositions influence recolonisation, they may be difficult to predict. Similarly, recovery trajectories for stream communities after drought will differ among streams, depending on whether biofilm can develop during potentially short seasonal flows.

Riffle Beetle Communities of Perennial and Intermittent Streams in Northern Nevada, USA, with a New State Record forOptioservus castaneipennis(Fall) (Coleoptera: Elmidae)

Long-lived, benthic macroinvertebrate taxa are often poorly represented in intermittent streams because the periodic lack of water eliminates colonization habitat for those invertebrates, especially among those for which burrowing is not part of their life history. In the western United States, elmid beetles, which do not burrow, have a multiple-year life cycle, and multiple species are often found coexisting, even in intermittent streams. The elmid beetle communities of 21 sites on eight streams in northern Nevada were examined to determine patterns of occurrence and their relation to water permanence in those streams. Samples were collected in June 2006, May 2007, September 2010, and July 2011. In two streams, no elmid beetles were collected, probably due to the habitat not being conducive to elmid beetle presence (mucky substrate). Among the perennial stream sites, one or two species were consistently dominant, and the relative abundances of species were similar throughout all years. In contrast, elmid beetles were often, but not always, absent from intermittent streams even when water was present, and species dominance was usually different among the years when elmid beetles were present in those streams. These data suggest a strong role of opportunistic colonization in intermittent headwater streams, with more stable communities fostered by perennial streams. Collection records are presented for Optioservus castaneipennis (Fall), new state record, which heretofore had not been reported from Nevada.

A New Species ofProceratophrys(Anura: Cycloramphidae) from Midwestern Brazil

Abstract We describe adult morphology, advertisement call, and natural history aspects of a new frog species from riparian habitats alongside intermittent headwater streams in southwestern Cerrado, the second largest biome in Brazil. Presently known from three localities in Mato Grosso State, the new species belongs to the Proceratophrys cristiceps group. It is characterized mainly by small size (adult snout–vent length approximately 46 mm), snout rounded in dorsal view and obtuse in lateral view, absence of flared lips, dorsal skin granular, and absence of both postocular swellings and prominent palpebral appendages. The advertisement call of the new species consists of a single note with 19–25 pulses. Calls are repeated at mean intervals of 0.7 sec. Mean dominant frequency is 1,250.2 Hz, with ascendant modulation.

Movement patterns of southern redbelly dace, Chrosomus erythrogaster, in a headwater reach of an Ozark stream

AbstractPrevious research on fish movement has focused primarily on recreationally important fishes in perennial streams; however, fewer studies have examined movement patterns of small‐bodied fishes in intermittent streams where abiotic and biotic conditions can be extreme compared with perennial systems. Using mark–recapture, we examined movement patterns of southern redbelly dace, Chrosomus erythrogaster, in an intermittent Ozark stream having both permanently connected and temporally isolated sections. Juvenile (60–88%) and adult (55–83%) residency rates were not significantly different for any mark–recapture sample, and movement was primarily within a section for both groups. Ontogenetic differences were detected for kurtosis, distance moved and population spread, with adults exhibiting greater variability in movement, moving more often and further. When considering only adults, there was a significantly higher number of individuals that exhibited intermovement from isolated sections compared with connected sections. In addition, a higher proportion of adults exhibiting intermovement moved to connected stream sections in May and July compared to January and March. Dace exhibited upstream bias in July, with 76% of emigrates moving to an upstream connected section. Although there were no statistically significant associations between the proportion of intermovers from connected and isolated sections and measured water quality and habitat variables, noteworthy trends were observed, and these trends were always stronger for connected sections. Understanding the factors that influence population dynamics in headwater streams is important for the survival and persistence of stream fish populations, especially considering the anticipated expansion of intermittent headwater streams as a result of future climatic changes.

Life histories and life history strategies of invertebrates inhabiting intermittent streams in Hawke's Bay, New Zealand

Intermittent streams are predicted to harbour macroinvertebrate taxa with particular life history traits that allow them to complete development in a limited time and survive periods without water. Three intermittent headwater streams in Hawke's Bay, New Zealand, had more taxa with very small body size, plurivoltine life cycles, low dissemination potential, long-lived adults and asexual reproduction than three nearby perennial streams. We traced the population size structure and adult flight periods of six aquatic insect taxa, and the population size structure of an aquatic snail, in three intermittent streams to provide basic information on larval growth rates and infer whether they use particular life history stages to survive summer drought. The insect taxa appeared to over-summer primarily as eggs, whereas the snail Potamopyrgus antipodarum over-summered at various stages of maturity. Final instar larvae and adults of most insect taxa appeared well ahead of stream drying, suggesting they can survive early-onset drought. However, late-onset drought would allow more larvae to complete development.

Invertebrate colonization of leaves and roots within sediments of intermittent Coastal Plain streams across hydrologic phases

Ecological flows between habitats are vital for predicting and understanding structure and function of recipient systems. Ecological flows across riparian areas and headwater intermittent streams are likely to be especially important in many river networks because of the shear extent of these interfaces, their high edge-to-width ratio, and the alternation of wet and dry conditions in intermittent channels. While there has been substantial research supporting the importance of riparian-stream linkages above-ground, comparatively less research has investigated below-ground linkages. We tested the hypothesis that riparian roots are colonized by invertebrates as a food source within stream beds of intermittent headwater streams. We compared benthic invertebrate assemblages colonizing three types of buried substrates (leaves, roots, and plastic roots) among three intermittent Coastal Plain streams, each with a different riparian management treatment (clearcut, thinned, and reference), over a 1-year period. Invertebrate density was significantly lower in root litterbags than in plastic roots litterbags, but neither differed from densities in leaf litterbags. Total invertebrate abundances, however, were significantly higher in leaf and root litterbags compared to abundances in plastic root litterbags. Invertebrate biomass and richness did not vary among substrates, but invertebrate density, abundance, and richness all declined from the wet phase (September–December) through the dry phase (June–August). Meiofauna and aquatic dipterans were the primary colonizing invertebrates during the wet phase. Relative abundance of terrestrial taxa increased during the dry phase, but their absolute abundance remained lower than aquatic taxa during the wet phase. Invertebrate composition did not differ among substrate types, but was significantly different among streams and time periods. Cumulative number of dry days, degree days, and redox depth all strongly correlated with assemblage structure as indicated by ordination scores. Our results suggest that subsurface invertebrates respond to leaves and roots as food sources, but assemblage composition is not substrate specific. Colonization of leaves and roots within stream beds by aquatic and terrestrial taxa supports the idea that headwater intermittent streams are important interfaces for the reciprocal exchange of energy and materials between terrestrial and aquatic ecosystems.

A multiple watershed field test of hydrogeomorphic functional assessment of headwater streams—Variability in field measurements between independent teams

Ephemeral and intermittent headwater streams are under increasing pressure from disturbance and development. Rapid, repeatable assessment techniques are needed in order to gauge the condition of these stream systems. Several attributes of these headwater streams constrain the use of the most widely used macroinvertebrate or water quality stream assessment techniques. The hydrogeomorphic (HGM) functional assessment is a reference-based alternative technique. To evaluate this alternative, repeated assessments were conducted in eight high-gradient headwaters in West Virginia by four independent teams. Across-site and measurement variance among teams was assessed using a coefficient of variation (CV, expressed as percent). A variability of >50% CV, which suggests less repeatable results, occurred in only 13.8% of measurements, primarily associated with 2 of the 9 variables examined (snag density and substrate size). Between site measurement variance was the greatest at more highly disturbed sample locations, particularly with regard to the large woody debris, tree species richness, and channel bank erosion variables. Variables with the lowest CV were tree diameter, detrital cover, canopy cover, and channel embeddedness. Based on these results, measurements included when applying HGM approach to these streams should focus on direct measurements or directed estimates that yield a large response range across a spectrum of sites while maintaining consistent repeatability among different teams, with special attention paid to their use in highly disturbed sites.

Potential impacts of global climate change on the hydrology and ecology of ephemeral freshwater systems of the forests of the northeastern United States

Global, national, and regional assessments of the potential effects of Global Climate Change (GCC) have been recently released, but not one of these assessments has specifically addressed the critical issue of the potential impacts of GCC on ephemeral freshwater systems (EFS). I suggest that this is a major oversight as EFS occur in various forms across the globe. In the northeastern United States, these systems, whether ephemeral (“vernal”) pools or ephemeral or intermittent headwater streams are abundant and provide unique habitats critical to the maintenance of forest biodiversity. Since the hydrology of these waterbodies is strongly affected by weather patterns (in the short-term) or climate (long-term), they are especially sensitive to climate change. In this essay, I review the literature on relationships between climate and hydrology of EFS and on relationships between hydrology and ecology of these systems. I then conclude with my assessment of potential impacts of GCC on the hydrology of EFS and implications for their ecology. The focus of this essay will be on EFS of the forests of the northeastern United States, but will include literature from other regions as they relate to the general relationships between GCC and EFS.

Composition and temporal changes in macroinvertebrate communities of intermittent streams in Hawke's Bay, New Zealand

Macroinvertebrate communities in three stony‐bottomed intermittent headwater streams in central Hawke's Bay, New Zealand, were sampled once per month (on average) for 11 months from autumn 2005 to summer 2006, and compared with communities in three perennial streams and three intermittent streams with perennial headwaters. Among the intermittent headwater sites, 95 taxa were found, with Oligochaeta, Copepoda, Chironomidae, and Ostracoda occurring in greatest abundance. Eight mayfly, 6 stonefly and 16 caddisfly species were found. Macroinvertebrate abundance at intermittent headwater sites was equal to nearby perennial sites, but taxon richness per sample was lower. Community composition changed progressively during the autumn‐to‐spring flow period (March‐November 2005) at one intermittent headwater site, but at the other two sites a directional change was not evident, probably because stream flow stopped briefly several times during the flow period. Most of the taxa collected in riffles during the flow period were also in disconnected pools after flow stopped in summer (January 2006), but some taxa were absent and the disconnected pools contained several additional species. The disconnected pools in January had higher macroinvertebrate density and richness than connected pools during the flow period. At intermittent sites with perennial headwaters, taxon richness and EFT (Ephemeroptera, Plecoptera, and Trichoptera) richness were intermediate between intermittent headwater sites and perennial streams. Two weeks after flow began, the intermittent sites with perennial headwaters showed much higher EPT abundance and richness than the intermittent headwater sites, but after 8 weeks the proportional difference was less.

Associations of watershed vegetation and environmental variables with fish and crayfish assemblages in headwater streams of the Pedernales River, Texas

AbstractIntermittent headwater streams serve important functions for humans and wildlife in semi‐arid rangelands. Increases in ashe juniper coverage in central Texas over recent decades are believed to have negatively impacted stream flows. Few studies have examined relationships between aquatic species and environmental factors in these systems as well as the influence of juniper coverage on assemblage structure. During summer 2003 and spring 2004, we examined species–environment relationships to infer potential effects of juniper cover on aquatic ecology relative to local‐scale and watershed‐scale environmental variables. Fish and crayfish species assemblages and physicochemical variables were investigated in spring‐fed headwater tributaries of the Pedernales River, Texas. Fish abundance was much higher in summer 2003, whereas crayfish abundance was higher in spring 2004. Fish species richness was lower during spring 2004, possibly due to below average precipitation during spring 2004 that reduced deep‐water refugia. Higher abundance of crayfish in spring 2004 samples was probably due to their ability to survive low‐flow conditions, and a release from fish predation pressure. Fish assemblage structure was more strongly associated with local abiotic factors during spring 2004 when flow was reduced, whereas structure during summer 2003 samples suggested a relatively greater influence of predation. In general, juniper cover was weakly associated with fish and crayfish assemblages, although it tended to be positively associated with relatively high‐quality habitat for sensitive taxa (flowing runs with coarse substrate; deep, connected pools). We suggest that intermediate levels of juniper cover in the region provide indirect benefits to aquatic organisms. However, short‐term, local environmental factors appear to have a much greater influence than watershed vegetation on fish and crayfish assemblages in these intermittent streams. Copyright © 2007 John Wiley & Sons, Ltd.

Riparian influence on hyporheic‐zone formation downstream of a small dam in the Blackland Prairie region of Texas

AbstractSmall‐order streams have highly variable flows that can result in large temporal and spatial variation of the hyporheic zone. Dam construction along these intermittent headwater streams alters downstream flow and influences the hydrologic balance between stream water and the adjacent riparian zone. A 3‐year site study was conducted along an impounded second‐order stream to determine the water balance between stream, unsaturated zone, groundwater and riparian vegetation. The presence of the upstream impoundment provided near‐perennial water flow in the stream channel. The observed woody plant transpiration accounted for 71% of average annual water loss in the site. The overall contribution of stream water via the hyporheic zone to site water balance was 73 cm, or 44% of total inputs. This exceeded both rainfall and upland subsurface contribution to the site. A highly dynamic hyporheic zone was indicated by high water use from woody plants that fluctuated seasonally with stream water levels. We found leaf area development in the canopy layer to be closely coupled with stream and groundwater fluctuations, indicating its usefulness as a potential indicator of site water balance for small dam systems. The net result of upstream impoundment increased riparian vegetation productivity by influencing movement of stream water to storage in the groundwater system. Copyright © 2006 John Wiley & Sons, Ltd.

Life History Phenology and Sediment Size Association of the Dragonfly <em>Cordulegaster dorsalis</em> (Odonata: Cordulegastridae) in an Ephemeral Habitat in Southwestern British Columbia

The life cycle of the dragonfly Cordulegaster dorsalis was studied over one year by systematic sampling of larvae in three intermittent headwater streams in southwestern British Columbia. We determined that larvae normally take three years to reach maturity, emerging throughout July and August. There is limited evidence suggesting a split cohort development, with early emergence after two years. Additionally, we tested whether larval instars were distributed randomly or if they occupied different sediment microhabitats. Smaller animals tend to be associated with smaller grained organic sediments, although there was high variation between the streams.

A Fish-Based Index of Biotic Integrity to Assess Intermittent Headwater Streams in Wisconsin, USA

I developed a fish-based index of biotic integrity (IBI) to assess environmental quality in intermittent headwater streams in Wisconsin, USA. Backpack electrofishing and habitat surveys were conducted four times on 102 small (watershed area 1.7-41.5 km(2)), cool or warmwater (maximum daily mean water temperature > or = 22 C), headwater streams in spring and late summer/fall 2000 and 2001. Despite seasonal and annual changes in stream flow and habitat volume, there were few significant temporal trends in fish attributes. Analysis of 36 least-impacted streams indicated that fish were too scarce to calculate an IBI at stations with watershed areas less than 4 km(2) or at stations with watershed areas from 4-10 km(2) if stream gradient exceeded 10 m/km (1% slope). For streams with sufficient fish, potential fish attributes (metrics) were not related to watershed size or gradient. Seven metrics distinguished among streams with low, agricultural, and urban human impacts: numbers of native, minnow (Cyprinidae), headwater-specialist, and intolerant (to environmental degradation) species; catches of all fish excluding species tolerant of environmental degradation and of brook stickleback (Culaea inconstans) per 100 m stream length; and percentage of total individuals with deformities, eroded fins, lesions, or tumors. These metrics were used in the final IBI, which ranged from 0 (worst) to 100 (best). The IBI accurately assessed the environmental quality of 16 randomly chosen streams not used in index development. Temporal variation in IBI scores in the absence of changes in environmental quality was not related to season, year, or type of human impact and was similar in magnitude to variation reported for other IBI's.

Biomass and Decay Rates of Roots and Detritus in Sediments of Intermittent Coastal Plain Streams

Biomass and breakdown of tree roots within streambed sediments were compared with leaf and wood detritus in three Coastal Plain headwater intermittent streams. Three separate riparian forest treatments were applied: thinned, clearcut, and reference. Biomass of roots (live and dead) and leaf/wood was significantly higher in stream banks than in the channel and declined with depth strata (0–10 > 10–20 > 20–30 cm). Riparian roots (live and dead combined) contributed on average 24 and 42% of coarse particulate organic matter (CPOM) biomass within the top 30 cm of channel and streambank sediments, respectively. Estimated mean surface area of live riparian roots within sediments was 1084 cm2 m−3. Streambed temperatures showed greater fluctuation at the clearcut site compared to thinned and reference treatments. However, breakdown rates among buried substrate types or riparian treatments did not differ after 1 y. Slow decay rates were associated initially with anaerobic conditions within sandy sediments and later with dry sediment conditions. Riparian roots represent a direct conduit between streamside vegetation and the hyporheic zone. In addition to contributing to organic matter storage, the abundance of riparian roots within streambed sediments suggests that roots play an important role in biogeochemical cycling within intermittent headwater streams of the Coastal Plain.