Small Forest Streams Research Articles

Food type and temperature constraints on the fitness of a dominant freshwater shredder

Freshwaters receive a large amount of materials and biologically available energy from their surrounding catchments. In particular, small forested streams are dependent on allochthonous organic matter inputs. However, since the middle 20th century large areas of forests in the Iberian Peninsula have been converted to eucalypt plantations, impairing invertebrate communities and stream energy fluxes. In addition, the dependence of organismal metabolic rates on temperature may influence invertebrate life cycles and development, and ultimately the riparian-stream system. We tested the effects of two food resources (alder and eucalypt) under two different temperatures (9 vs. 14°C) on the life history parameters and elemental composition of Brillia bifida (Chironomidae), a numerically dominant shredder in forested streams of NW Spain. Our results showed: (i) warmer temperature accelerated the development of B. bifida larvae (i.e., three times faster at warm than at cold temperature), (ii) Brillia's growth rate when fed on eucalypt leaves was only 30% of what it was on alder leaves, and (iii) both factors together modified larvae stoichiometry and nutrient fluxes (i.e., through fine particulate organic matter production). The observed elemental imbalances suggest, to some extent, a deviation from the “strict homeostasis” assumption for heterotrophs. Differential effects observed on larval development, growth and elemental composition point out that food type and temperature are influencing B. bifida performance, and this fact may reach other trophic compartments through detritivore-mediated nutrient cycling.

Magnesium isotopes in permafrost-dominated Central Siberian larch forest watersheds

To unravel the Mg isotope fractionation pathways within the continuous permafrost zone in the larch deciduous forest of Central Siberia, we measured the Mg isotopic composition of two large Siberian rivers (Nizhnaya Tunguska and Kochechum, which flow into the Yenisey), a small forested stream, and the major fluid and solid sources of Mg in the watershed: atmospheric precipitates, surface suprapermafrost flow, interstitial soil solutions, plant biomass, litter and mineral soils. The obtained results indicate a significant seasonal variation in riverine water Mg isotope signatures. During the winter baseflow, the Mg isotope composition of large rivers is significantly lighter than the source basaltic rocks and the atmospheric depositions. These differences support the presence of fluids enriched in lighter Mg isotopes, such as those affected by the mineral precipitation of secondary silicates or fluids that dissolve sedimentary carbonate rocks. During the spring flood and in the summer and fall seasons, the river fluid δ26Mg values increased by 0.2–0.3‰ and approached the Mg isotope composition of the ground vegetation (dwarf shrubs, mosses) and the soil organic horizon. Overall, the riverine waters were 0.3–0.7‰ lighter than the unaltered bedrock and the deep minerals soil horizons.The Mg isotopic compositions of Larix gmelinii organs (i.e., stem wood, roots and needles) exhibit a low variability. However, an enrichment of 0.2–0.3‰ in the δ26Mg of larch needles in the course of the growing season, from June to September can be observed. This enrichment most likely demonstrates uptake of isotopically heavier Mg by the plant in addition to the progressive thawing of the mineral soil (deepening of the active layer of the soil). Overall, the Mg isotope approach indicates the important contribution of vegetation (larch needles, mosses and dwarf shrubs) to the riverine Mg isotope signature and helps to reveal the contribution of isotopically light carbonate rocks in the large rivers of the Central Siberian Plateau.

Taxonomic revision of Australian Platynectes Régimbart, 1879 (Part I)-four new species from Queensland (Coleoptera: Dytiscidae, Agabinae).

Four species of the genus Platynectes subgenus Gueorguievtes Vazirani, 1976 are described from Queensland, Australia: Platynectes brancuccii sp. n. (Atherton Tableland), P. larsoni sp. n. (Mulgrave Range and Windsor Tableland), P. ponderi sp. n. (Carnarvon Range) and Platynectes weiri sp. n. (White Mountains National Park and Hope Vale Mission). The latter two are the first species of the genus with striae on elytra and the informal P. weiri-species group is established for them. Platynectes brancuccii sp. n. and P. larsoni sp. n. belong to the P. decempunctatus-species group. All four species were collected from small rain forest streams or rest pools of intermittent creeks. Important species characters (median lobes, parameres and colour patterns) of all species are figured, and notes on their distribution and ecology are given. Altogether 17 species of the genus are now known from Australia.

Stream Temperature and Streamside Cover 14-17 Years after Clearcutting along Small Forested Streams, Western Oregon

Stream temperatures were monitored on seven low-elevation western Oregon streams immediately after clearcut harvesting and 14–17 years later in two studies that examined buffer designs. One study on four streams used no-tree buffers with all trees next to the stream harvested within the clearcut units. The second study on three streams examined partial buffers designed to shade the stream only from direct sun. Streams with no-tree buffers in clearcuts 90 or 180 m long mostly exhibited significantly less warming 16–17 years after harvest than 1–5 years after harvest. Streams with partial buffers had originally shown slight response to harvest, and 14–15 years after harvest temperature trends were not different from preharvest trends. Percent cover and estimated radiation 14–17 years after harvesting were mostly similar in harvested and uncut areas. The exceptions were areas close to the streams that were cleared by beavers (Castor canadensis), where streams were wide resulting in canopy openings, and where gravel bars with minimal plant development occurred. Planted conifers in no-tree riparian areas provided less shade than hardwoods and were mostly suppressed by hardwoods or damaged by beavers.

Omnivores as seasonally important predators in a stream food web

AbstractOmnivory is prevalent in terrestrial and aquatic food webs. However, the extent and seasonality of predatory feeding by omnivores in stream food webs is largely unknown. To understand better these aspects of omnivory in stream food webs, we investigated seasonal changes in the trophic positions of 2 omnivores in a small forested stream. We selected the amphipod, Gammarus pulex, and the caddisfly larvae, Hydropsyche spp., as key organisms because both taxa are common, reach high biomasses in many stream ecosystems, and have broad food spectra. We used stable-isotope analysis of the most prevalent taxa in the benthic macroinvertebrate community to assess the trophic positions of the 2 omnivorous taxa in different seasons. We estimated the degree of predatory feeding by quantifying the importance of different food resources with a stable-isotope mixing model (IsoSource). The predation capacity of omnivores, defined as the fraction of omnivore biomass associated with predation, was compared to the bio...

Persistent effects of acidification on stream ecosystem structure and function

AbstractAcidification of surface water is a persistent threat to aquatic ecosystems throughout the world. Several international policies have led to successful reductions of emissions of acidifying gases, but recovery of surface-water quality has been modest. Associated biological communities continue to suffer, and research on ecosystem functional response is sparse. We investigated shifts in macroinvertebrate communities, shifts in whole-stream metabolism, whether whole-stream metabolism is as sensitive an indicator of acidification as is benthic community structure, and shifts in stream food webs in 9 small forested streams exhibiting a pH gradient from 4.0 to 7.7 and belonging to the GEOchemical MONitoring (GEOMON) Network in the Czech Republic. Acidification was related to changes in macroinvertebrate communities including reduced taxon richness and reduced Ephemeroptera family richness and abundance. Whole-stream metabolism was not significantly related to stream pH and may be less sensitive to acid...

The effects of wood on stream habitat and native fish assemblages inNewZealand

AbstractHistoric deforestation has deprived many river systems of their natural wood loadings. To study the effects of the loss of wood from waterways, a field trial was conducted in three small forested streams inNewZealand. The objectives were to (i) examine differences in fish assemblages among wooded pools (where wood provided cover), open pools and riffles and (ii) measure the effects of wood removal on channel morphology and fish assemblages. In the first part of the study, no significant differences were found in total fish density among the three habitats. However, total fish biomass was significantly higher in wooded pools (64% of total fish biomass) compared with open pools and riffles. Mean density and biomass of banded kokopu (Galaxias fasciatus) and mean biomass of longfin eel (Anguilla dieffenbachii) were highest in wooded pools, whereas the density and biomass of bluegill bully (Gobiomorphus hubbsi) and torrentfish (Cheimarrichthys fosteri) were highest in riffles. In the second part of the study, wood was removed from a 200‐m section (treatment) in each stream, significantly reducing pool area and increasing the proportion of channel area and length in riffles. At the habitat scale, banded kokopu and large longfin eel were the two species mostly affected by wood removal. At the reach scale, banded kokopu biomass was significantly lower in the treatment sections. Although wooded pools were a small portion of total habitat, they provided important habitat for two ofNewZealand's larger native fish taxa.

Description of Apistogramma paulmuelleri sp. n., a new geophagine cichlid species (Teleostei: Perciformes) from the Amazon river basin in Loreto, Peru

A new species of Apistogramma is described from Peru, based on a total of 28 specimens collected in a small forest stream in the catchment of a nameless tributary of the Rio Amazonas about 80 kilometres south of Iquitos, Departamento Loreto (approximately 73° 34′ W / 04°24′ S). At first sight Apistogramma paulmuelleri sp. n. resembles A. regani, but is differentiated from the latter and all other Apistogramma species by the combination of a large band-like spot on the caudal-fin base, four distinct abdominal stripes, a roundish, banded caudal fin, a low dorsal fin without any striking features, in adult males yellow on the chin between the gill covers and on parts of the branchiostegal membranes, ivory sides to the head below the cheeks, and reversal of the band pattern during aggression and courtship display. Apistogramma paulmuelleri sp. n. is currently thought to be a representative of the Apistogramma eunotus complex within the Apistogramma regani lineage.

A comparison of surface and subsurface controls on summer temperature in a headwater stream

AbstractThis study compared summer stream temperature between two years in the Star Creek catchment, Alberta, a headwater basin on the eastern slopes of the Canadian Rocky Mountains. Star Creek is a subsurface water dominated stream, which represents important habitat for native salmonid species. Hydrometeorological data from May to September of 2010 and 2011 accompanied by stream energy budget calculations were used to describe the drivers of stream temperature in this small forested stream. Mean, maximum, and minimum weekly stream temperatures were lower from May to August and higher in September 2011 compared to 2010. Weekly range in stream temperature was also different between years with a higher range in 2010. Inter‐annual stream temperature variation was attributed discharge differences between years, shown to be primarily governed by catchment‐scale moisture conditions. This study demonstrates that both meteorological and hydrological processes must be considered in order to understand stream temperature response to changing environmental conditions in mountainous regions. Copyright © 2013 John Wiley & Sons, Ltd.

Diving in the sand: the natural history of Pygidianops amphioxus (Siluriformes: Trichomycteridae), a miniature catfish of Central Amazonian streams in Brazil

The natural history of Pygidianops amphioxus de Pinna and Kirovskyi (Neotropical Ichthyology 9:493–504, 2011), a highly specialized sand-dwelling catfish species, was studied based on underwater observations in a small forest stream in the central Amazon. Information on the feeding and reproductive biology was obtained by means of analyses of preserved specimens. These miniature catfishes remained buried in the sand at the bottom of the stream and were never observed swimming in open water. The catfish consumed small benthic invertebrates, particularly Chironomidae larvae and Harpacticoida copepods, which were most likely captured by suction feeding inside the sand banks. Pygidianops amphioxus displays sexual dimorphism in the shape of the urogenital papilla and in the body length, with adult females being relatively longer than males. Sexually mature females were found throughout the year and carried a small number of proportionally very large oocytes. A short duration (24 h) experiment conducted in aquaria revealed that these small catfishes exhibit the predominantly nocturnal habits typical of most Siluriformes.

Life history and secondary production of Electrogena ujhelyii (Ephemeroptera: Heptageniidae) in a small forest stream in West Carpathians

In this study we focused on life history parameters of Electrogena ujhelyii. We studied life cycle, nymphal growth pattern, biomass and secondary production in a small, calcareous stream in Male Karpaty Mts (West Carpathians). The life cycle was univoltine with a large range in the size of nymphs during most samples dates. Mean annual density was 40 ind. m−2 and the annual secondary production reached 183 mg DW m−2 y−1. There are no published data available on the secondary production values of this species, therefore these are the first published data.

Abundance and body condition of sculpin (Cottus spp.) in a small forest stream following recolonization by juvenile Coho Salmon (Oncorynchus kisutch)

Recolonization by native species following reintroduction can affect resident species through a variety of processes. We examined the effects of natural recolonization by coho salmon Oncorhynchus kisutch on sculpin (Cottus rhotus and Cottus gulosus), small benthic fishes, in a small forest stream in Western Washington, USA. Provision fish passage around a small dam allowed coho access to habitat, which had been inaccessible for over 100 years. We found that density (g m−2 and number m−2) was unchanged, and body condition (the slope of the relationship between length and weight) of sculpin tended to increase from before relative to a 5-year period following recolonization. The proportion of sculpin comprising the total fish assemblage decreased after coho colonization relative to before but remained stable for a 5-year period after coho reintroduction, whereas coho density increased over fivefold. Additionally, we used Akaike's information criteria to evaluate the relative importance of physical and biological variables to predict sculpin density in pool habitats during the initial coho recolonization period. Physical microhabitat variables had little support for predicting sculpin density, whereas there was a significant support for stream temperature; cutthroat trout (Oncorhynchus clarkii) density and year were the most important predictors of sculpin density. Coho density was not significant in any model. Our results indicate coho introduction and subsequent recolonization have to date had minimal individual or population level effects on sculpin, therefore demonstrating that species reintroductions into their native range can have no measurable effect on resident organisms. Published 2013. This article is a U.S. Government work and is in the public domain in the USA.

Assessing electric fishing sampling effort to estimate stream fish assemblage attributes

AbstractTheEU WaterFrameworkDirective (WFD) obligates authorities to assess the ecological status of rivers. The sampling of the fish assemblage must be based on a reliable and cost‐effective monitoring programme, and it should be optimised to measure the ecological quality cost‐effectively. The efficiency of single‐pass versus three‐pass backpack electric fishing was measured to assess ecological status. The data included 295 electric fishing samplings from 137 rivers inFinland and a 5‐year data series from six small forest streams in mid‐easternFinland. Compared with three‐pass electric fishing, single‐pass electric fishing in the same area increased the risk of missing rare fish species and species with low catchability. The concordance of the calculated fish metrics (e.g. proportion of tolerant and intolerant species) between one‐ and three‐pass measurements was, however, high, suggesting that single‐pass electric fishing was a suitable sampling procedure to evaluate ecological status. Increasing the area sampled by single‐pass removals stabilised the variances in the fish metrics and similarity indexes. It was concluded that in small streams electric fishing an area 24–27 times the stream width and in general a minimum of 300 m2, but preferably more than 450 m2, was adequate to estimate fish assemblage attributes reliably in boreal streams.

Influence of small-scale gold mining on French Guiana streams: Are diatom assemblages valid disturbance sensors?

The ongoing gold-rush in French Guiana could cause severe disturbance to ecosystems. Although illegal, small gold mining sites are rapidly expanding. Few studies have attempted to measure the consequences of the increased gold mining on the biota of small forest streams, and to date no study has dealt with primary producers. Here we measured the response of diatom assemblages to gold mining in ten sites differently affected by the mining activity (i.e., reference, formerly gold-mined and currently exploited). Our results showed that both taxonomic and functional structure of the diatom assemblages were influenced by the intensity of gold mining activity. A significant relationship between soil erosion and diatom motility ability has been demonstrated. These findings show that diatom assemblages are sensitive to gold mining disturbance and suggest that diatom communities may be used as sensors of the environmental stress caused by small-scale gold mining activities.

Short-term Impacts of Fish Removal from Small Amazonian Forest Streams

Collecting freshwater zoological material for research purposes is common and necessary, but its impact on biological communities is often overlooked. We tested the impacts of a conventional ichthyological collection in small forest streams and showed that fish assemblages recover after a few months. We highlight ecological traits and habitat characteristics that might exacerbate the impacts of repeated removal of fish in long-term investigations, and advocate for the use of a capture-release approach whenever possible.

Small-scale gold mining erodes fish assemblage structure in small neotropical streams

The current gold rush experienced by the Guiana shield is profoundly disturbing freshwater ecosystems. Indeed, streams act as receptors for the water that drains gold mining sites and that contain a high load of sediment and toxicants. We here investigated how gold mining activities affect the structure of fish assemblages in small forest streams in French Guiana. We selected six streams subjected to different types of gold mining impact (reference, former gold mining and currently exploited sites) to measure the impact of gold mining on downstream fish assemblages, but also to determine the resilience of fish assemblages after stopping mining activities. Although overall descriptors of the assemblage such as species richness and fish biomass were not sensitive to gold mining, the fish taxonomic composition was strongly influenced. Furthermore, we showed that the functional structure of fish assemblages was significantly affected by the mining activities favouring smaller and ubiquitous fish at the expense of bigger and habitat specialist species. Even in areas where mining activities had stopped for some time, site resilience was incomplete.

Leaf litter retention in tropical streams in Hong Kong

Leaf litter can be an important food resource in small forest streams, but its availability to detritivorous macroinvertebrates depends on stream retentiveness. Previous work in Hong Kong streams revealed a scarcity of large detritivores, and it is possible that this reflects the availability or instability of litter resources. Using leaf analogues made from waterproof paper, we undertook short-term experiments to measure the retentiveness of eight Hong Kong streams under baseflow conditions during the dry season; four streams had coarse bed sediments (boulder dominated) and four had relatively fine sediments (cobble-gravel dominated). Initially we compared the transport properties of soaked and unsoaked leaf analogues with the leaves of four native trees in one of the streams. Soaked and unsoaked analogues were used to mimic waterlogged and newly-fallen leaves. Mean travel distances (S p ) of leaves and analogues in the study streams ranged from 1-22 m. These are comparable to values recorded from similar-sized streams in temperate latitudes. Unsoaked analogues traveled further (mean S p = 10.2 m versus 3.1 m) than soaked analogues in all study streams, but retention behaviour of analogues generally matched that of real leaves. Mean travel distances of both analogue types were unrelated to streambed sediment size or sediment heterogeneity, but travel distance of soaked analogues was positively related to stream discharge. Litter retention remained high over a six-day period in one of the streams, suggesting that litter would be readily available to detritivores during periods with stable discharge, and that the scarcity of shredders must be caused by other factors.

Revision of the Neotropical water scavenger beetle genus Guyanobius Spangler, 1986 (Coleoptera: Hydrophilidae: Chaetarthriini)

The genus Guyanobius Spangler, 1986 is revised and expanded. Two species, Guyanobius queneyi sp. n. (French Guiana, Suriname) and Guyanobius lacuniventris sp. n. (Venezuela), are described as new and the two existing species, Guyanobius adocetus Spangler, 1986 and Guyanobius simmonsorum Spangler, 1990, are redescribed. Prior records of G. adocetus from Suriname were erroneous and actually refer to G. queneyi sp. n. All known species of Guyanobius were collected in leaf packs in small forest streams. The discovery of the genus in the Venezuelan Andes adds a remarkable 1200 km westward extension to its known range. Diagnostic characters are illustrated and a key to species is presented.

Forest clearance increases metabolism and organic matter processes in small headwater streams

Small headwater streams are abundant components of the riverine landscape where critical biochemical processes occur that provide clean water, energy, and nutrients to downstream reaches. Disturbance to these systems as a result of human land use has the potential to affect downstream health. Rates of metabolism and organic matter processing were measured in 22 small forested headwater streams in 2 regions of Tasmania, Australia, to evaluate the effects of forestry disturbance. Twelve of these streams had been subjected to recent clearfell-burn-and-sow (CBS) harvest. Benthic metabolism was measured in small in situ chambers (production ranged from <0.001 to 21.845 mg C m−2 h−1 and respiration from <0.001 to 4.976 mg C m−2 h−1), whole-system metabolism was estimated based on relative habitat abundance (gross primary production ranged from <0.001 to 0.297 g C m−2 d−1 and daily respiration from 0.003 to 0.072 g C m−2 d−1). Algal growth potential was measured on nutrient diffusing pots (chlorophyll a ranged from <1.0 to 40.1 mg/m2), and cellulose decomposition potential was assessed with a cotton-strip assay (cotton tensile strength loss ranged from 17.8% to 38.3% in 28 d). Sometimes an increase in the variability of response is a consequence of disturbance, but in our study, the difference between forested streams and clearcut streams was a significant increase in the mean values of all functional variables. The degree of response depended on the underlying geology (broad-scale spatial variability) of the streams. Current management practices for small headwater streams in Tasmania do not protect instream processes from forestry disturbance in the short-term (i.e., 2–5 y), and we suggest that an investigation of long-term response is warranted.

Seasonal variation in the composition of fish assemblages in small Amazonian forest streams: evidence for predictable changes

Summary1. The effects of seasonal inundation on the biology of fishes on floodplains of large Amazonian rivers are well studied. However, the small seasonal changes in headwater streams are generally considered to have little effect on fish assemblages.2. In this study, we analysed seasonal changes in the species composition and abundance of fish in small Amazonian forest streams. We sampled fish with hand and seine nets in headwater streams in a 10 000 ha terra‐firme forest reserve near Manaus, Brazil. Each stream was surveyed at the end of the 2005 dry season, at the beginning of the 2006 rainy season and at the beginning of the 2006 dry season, by means of a standardized sampling effort.3. The numbers of individuals and species caught were higher in the dry season, but rarefaction analyses indicated that greater species numbers could have been due simply to the larger number of individuals caught.4. Between the dry and rainy season, the direction of changes in species composition in multivariate space varied among sites, especially for quantitative (abundance) data. However, the observed variation among sites was the less than expected if the directions of change were random.5. Fish assemblages in the second dry season were more similar to those in the previous dry season than expected if changes in species composition among seasons were random. This indicates that a general seasonal pattern in fish assemblages can be detected, despite the existence of some erratic site‐specific changes.6. Most of the species that showed large seasonal variations in density occupy temporary ponds during the rainy season, when much of the valley is inundated and pond networks form adjacent to streams. Short‐duration lateral migrations to these ponds may play an important role in the seasonal fish‐assemblage dynamics in Amazonian headwater streams.7. Our results contrast with previous studies on small Amazonian streams, which have found little seasonal change in fish assemblages, and highlight the importance of the abundance of common species as an indicator of general fish assemblage structure in biological monitoring programmes.