Ecology of algae in a subarctic stream

Abstract

Changes in the density of planktonic, epilithic, and epiphytic algae in a subarctic stream (Baker Creek) were estimated from collections made at least every 2 weeks between June 1975 and November 1976. Simultaneous determinations of 17 nutrients. pH, temperature, discharge, and the gut contents of 29 herbivorous animals were made. Multiple regression analysis indicated that temperature had the greatest overall effect on changes in the density of the plankton (Ankistrodesrnris frilcritus, Scerzedesnz~rs q~rrrdricrrrida, Nostoc pr~rnifortne, and Chlarnydornonas lapponictr) and epilithon (Nostoc prlrniforme) during the growing season. It was followed in significance by either NO3-N, hardness, or discharge. NO3-N was always primarily responsible for initiating changes in the epiphyton (Achnrrnthes rnirl~ttissirno, A. linearis, and Coccor~eisplrrccn-trrlrr). Temperature did, however, assume secondary importance followed by SiO,. Other environmental factors usually had little effect on all three communities. MOORE, J. W. 1977. Ecology of algae in a subarcticstream. Can. J. Bot. 55: 1838-1847L'auteur a estime les changements de la densite des algues planctoniques, Cpilithiques et Cpiphytiques, dans un ruisseau sub-arctique (Baker Creek), a partir de recoltes effectuies au moins.8 toutes les 2 semaines entre juin 1975 et novembre 1976. Simultanement, il a determine 17 elements nutritifs, le pH, la temperature ainsi que les excretions et les contenus intestinaux de 29 animaux herbivores. L'analyse par regression multiple indique que la temperature exerce I'effet general le plus important sur les changementsde ladensite du plancton (Ar~kistrodesmrrs fcrlcrrt~~s, Scenerlesrn~rs qrrrrdrico~rdo, Nostoc prrrniforn~e. Clzlrrmydotnonrrs lapponicrr) et sur I'epilithon (Nostocpr~rr~ifort~ze) au cours de la saison de croissance. En second rang d'importance on trouve soit le NO3-N, la dureti ou I'excrCtion. Le NO,-N est toujours implique de f a~o n preponderante avec I'initiation de changements dans I'kpiphyton (Achtlotlthes tninrrtissin~ri, A. lir~errri~, Cocconcis plncetztrrlrr). La temperature cependant a une importance secondaire suivie par SiO,. Les autres facteurs du milieu ont habituellement peu d'effets, sur ces trois communautes.[Traduit par le journal]

Influence of food availability and other factors on the composition, structure and density on a subarctic population of benthic invertebrates

“…Dissolved oxy-2 1 6 gen in water collected from bottom with a 4 1 Van Dorn bottle was determined by the Winkler-azide titration method . Phytoplankton was collected at 5 m depth intervals and at 0 .5 m from bottom using the same Van Dorn bottle and analyzed as in Moore (1977a) . The microflora associated with the sediments (epipelon) were sampled by pipetting off the upper 2 cm of sediment from a 50 mm diameter core collected at each station .…”

“…The microflora associated with the sediments (epipelon) were sampled by pipetting off the upper 2 cm of sediment from a 50 mm diameter core collected at each station . The density and species composition of the flora in these samples were analyzed as in Moore (1977a) . Core samples could not be taken during the winter due to low atmospheric temperatures .…”

Hydrological controls on the diatom assemblage of a seasonal arctic river: Boothia Peninsula, Nunavut, Canada

“…vaucheriae, Cymbella arctica, C. minuta, C. silesiaca, Encyonema fogedii and Diatoma tenuis in the river samples compared to the lake sediments suggest that these taxa are rheophilic in this environment. The ability of A. minutissima to adhere closely and firmly to substrata may account for its competitiveness in flowing waters (Peterson & Stevenson, 1992;Wehr & Sheath, 2003), including those in northern Europe (Vilbaste & Truu, 2003) and across the Canadian Arctic (Moore, 1977;Moore, 1979;Hamilton et al, 1994;Ludlam et al, 1996;Antoniades & Douglas, 2002). However, Ludlam et al (1996) noted that while A. minutissima was common in small stream and lake algal mat samples in a High Arctic catchment, it was rare in high energy stream samples, suggesting it is more representative of littoral environments.…”

“…However, Ludlam et al (1996) noted that while A. minutissima was common in small stream and lake algal mat samples in a High Arctic catchment, it was rare in high energy stream samples, suggesting it is more representative of littoral environments. In Arctic freshwater environments, A. minutissima has been associated with the epilithon (Douglas & Smol, 1993), although strong affinities for the epiphyton (Moore, 1977;Lim et al, 2001a) or no appreciable affinity for a particular habitat (Antoniades & Douglas, 2002) have also been observed. Given the comparable relative abundances in rock and moss samples it appears that A. minutissima is equally competitive on both of these substrates in the Lord Lindsay River as well.…”

Zooplankton, and related phytoplankton cycles, in a eutrophic lake

“…pH and the concentrations of Na, K, Cl, SO4 and total hardness were determined as outlined in Moore (1977b) .…”