The Ecology of Temporary Streams I. The Faunas of Two Canadian Streams

Abstract

This, thefirst of two papers on the ecology of temporary streams, describes, in detail, the faunas of two such habitats in southeastern Canada. The adaptive mechanisms for coping with the summer drought are documented for a variety of species and faunal succession is shown to occur from the stream stage (fall-winter) through the pool stage (spring) to the terrestrial (summer). I. IntroductionThis is the first of two papers dealing with the ecology of temporary stream faunas. I n it, we propose to present the detailedfindings of work on two temporary streams in Ontario, Canada. This will lay the foundations for the second paper in which we will attempt to summarize what is known of these habitats and to underline how the members of what is essentially an aquatic community, deal with the terrestrial phase of their environment. Previous literatureThere have been few studies on temporary streams as such, but there is a copious literature dealing with temporary ponds and other small water bodies. Whereas the differences between permanent lotic and lentic habitats may be very considerable indeed, in the temporary water situation, because many of these streamsflow slowly and often dry up to pools, we find considerable overlaps.ABELL (1956) in a study of intermittency in foothill streams of central California, made extensive faunal lists and tried to explain these in terms of three groups: 7 62 D. D. WILLIAMS and H. B. N. HYNES 1. a rapidly appearing but essentially temporary fall association which tended towards a herbivo-2. a winter and spring succession which tended to replace the fall forms and represented a step 3. a summer cleanup crew consisting mostly of predators and scavengers. He found that these animals employed three methods of survival in the dry stages of these habitats, namely, dormancy within the habitat, transfer of activity to another environment, and retreat to a more favourable habitat to await resumption of flow. The latter was apparently the most variably and successfully used, permitting almost any sort of life history timing. Eighty percent of ABELL'S temporary stream fauna were insects.CLIFFORD (1966) in a study of a temporary stream in Indiana, divided the fauna into two groups with respect to season. The first was a late summer-fall association, characteristic of the stream when i t was dry or nearly so. It consisted of adventitious species and adult aquatic beetles. The second was a later winter-spring association, characteristic of conditions of flow. Its constituents were mainly permanent residents which appeared year after year and were the basis for a stable community. Apparently, many of the latter were not specifically adapted t o this kind of environment, but possessed certain pre-adaptations which favoured them over others. Lirceus fontinah and Crangonyx forbesi were the two most abundant organisms and both survived the summer drought as small individuals buried in the substrate.HARRISON (1966) observed that the Munwahuku stream near Salisbury, Rhodesia, became dry for 3 mo...

Spatial and temporal patterns of benthic invertebrate communities in an intermittent river (North Africa)

“…These contrasting results could be due to different concepts of «temporary sites» in different works, as some authors consider them as sites that dry up completely in summer, whereas others refer to rivers that have isolated pools during the dry period (Bonada 2003). The dry season length has been recognized as one important factor determining the biological diversity in these streams (Williams & Hynes 1976, Abell 1984, Williams 1996, Bonada 2003. Thus, further comprehensive studies on the effects of frequent absence of flow and insufficient flow on benthic communities are needed, probably supporting the intermediate disturbance hypothesis (Connell 1978), which assumed that high species diversity is a result of intermediate frequency of disturbance, while either too low or too high frequency of disturbance will reduce biodiversity (Jørgensen & Padisak 1996).…”

“…The drying process poses several physico-chemical and biological challenges to the biota of intermittent streams (Williams 1996). The patterns of water disappearance are of fundamental importance, whether they are predictable (i.e., part of a stable cycle) or unpredictable (i.e., linked to the vagaries of local climate) (Williams & Hynes 1976, Wiggins et al 1980, Delucchi 1988. The length of the dry period thus influences the decrease in habitat size.…”

Influences of geology and land use on macroinvertebrate communities across the Motueka River catchment, New Zealand

“…Macroinvertebrate communities in intermittent flow environments are likely to have less diversity than in perennial environments and especially so if sub-surface flow permanence is low (Datry et al 2007;Storey & Quinn 2008). When flow resumes in intermittent environments, the main sources of invertebrate colonisation will be through aquatic invertebrate drift, aerial colonisation, upstream migration and vertical migration through the hyporheos (Williams & Hynes 1976;Sagar 1983;Fowler 2002Fowler , 2004. The lower diversity and density of invertebrates in one of the Moutere gravel exotic forest streams and dominance of particular groups of invertebrates (Diptera, Potamopyrgus) that are often associated with ephemeral streams in the other two streams could be an indication of invertebrate communities in the process of recovery from a period of flow intermittence (Storey & Quinn 2008).…”

Review: From multi-scale conceptualization to a classification system for inland groundwater-dependent ecosystems

“…Thus, the plant size, form and stand structure, together with the strength of its stems and method of anchoring, constrains its presence to a specific physical environment. For example, Reactions are facilitated by bacteria and geochemically active sediment coatings (see Williams and Hynes 1976;Boulton et al 2010). Aerobic species may completely use up oxygen at some distance into the streambed, and then may be replaced by organisms adapted to or specialized for hypoxic conditions.…”