Growth characteristics of bloom-forming filamentous green algae in the littoral zone of an experimentally acidified lake

Abstract

Filamentous green algae, predominantly Mougesfia and Zygogonium, bloom frequently in the littoral zones of acidified lakes. Growth characteristics of Zygogsnium-dominated filamentous green algae were studied for 4 yr in an experimentally acidified (pH 4.5) lake at the Experimental Lakes Area of northwestern Ontario. They were present in low abundance as periphyton (algal associations attached to surfaces) during spring, and as blooms of metaphyton (benthic algae unconstrained by surfaces) beginning in midsummer and reaching a maximum in early fall. Metaphytic filamentous green algae displayed high photosynthetic capacity in summer despite the oligotrophic nature of the acidified lake. The ma~or factors controlling photosynthetic rates of Zygogonium were similar to those controlling Msugeotia, and included algal crowding, irradiance, dissolved inorganic carbon, and water temperature. Rates of photosynthesis were negatively dependent upon algal crowding, so that highest rates were associated with minimum algal crowding. Light requirements for photosynthesis were higher than those of the epilithon, which were dominant prior to acidification. The dependence of photosynthesis on ambient concentrations of dissolved inorganic carbon was partly regulated by water temperature. Anthropogenically caused releases from growth limitations (e.g., increased availability of limiting nutrients, increased water temperature, and extension of the growing season) may cause proliferation of filamentous green algae in the future.RCsnmC : Les chlorophycCes filamenteuses (algues vertes), surtout Mougeotia et Zygogonium, prolierent souvent dans les zones littorales des lacs acidifies. Les caract~ristiques de croissance des chlorophycCes filamenteuses ii prCdominmce de Zygsgonium ont fait I'objet d9Ctudes 6chelonnCes sur 4 ans dans un lac acidifik expkrimentalement (ti un pH de 4,5) Bans la region des lacs expCrimentaux du nord-ouest de 190ntario. Ces algues Ctaient prtsentes en faible abondance sous forme de pgriphyton (associations algales fixCes B des surfaces) au cours du printemps, et sous forme d'efflorescences du mktaphyton (algues benthiques non liCes B des surfaces), commenqant B proliferer au milieu de 1' CtC et atteignant un niveau maximal au &but de l'automne. Les algues vertes du mktaphyton prksentaient une grande capacitg photosynthCtique en Ct C malgrC le caractkre oligotrophe du lac acidifiC. Les principaux facteurs rCgissant la photosynthkse de Zygogonium Ctaient semblables ii ceux qui sont la base de la photosynth8se de Ikfougeotia, notamment la BensitC Be peuplement, 1'Cclairement CnergCtique, le carbone inorganique dissous et la temperature de l'eau. La photosyntfii5se Ctait inversement proportionnelle ti la densite des algues, le taux le plus ClevC Ctant observe aux endroits 06 la densite de peuplement Ctit minimale. Les besoins en Cclairement aux fins de la photosynth8se Ctaient supdrieurs ceux de I'Cpilithon, qui dominait avant I'acidification. La Bependance de la photosynth2se ti l'tgard des concentrations mbiantes

Responses of periphyton to artificial nutrient enrichment in freshwater kettle ponds of Cape Cod National Seashore

“…Analyses of communities harvested from periphyton samplers in 2004 showed that Mougeotia species (filamentous green algae) comprised the vast majority of algal biomass (Smith, 2004). The amount of available attachment area in each pond, and thus the amount of periphyton, varies with aquatic plant biomass, which itself is linked to pond trophic status and successional stage, While no direct quantification has been done, the biomass of periphyton relative to phytoplankton in the ponds appears to be relatively high, as is frequently the case in acidic waters (Turner et al, 1995;Winkler, 1997;Vinebrooke et al, 2002).…”

Algal responses to dissolved organic carbon loss and pH decline during whole‐lakeacidification: Evidence from paleolimnology

“…Benthic communities were also affected by the acidification of L302S (Turner et al 1987(Turner et al , 1995aFindlay et al 1999). In general, net photosynthesis of epilithon declined (Turner et al 1995c) as cyanobacteria were replaced by chlorophytes and dinoflagellates during ice-free seasons (Findlay et al 1999).…”

“…Laboratory and field experiments demonstrate that algal growth can decline with pH (e.g., Stokes 1981;Vinebrooke 1996). In contrast, field surveys document that acidification results in species replacements (Turner et al 1987;Howell et al 1990;Nichols et al 1992), although not necessarily a decline in production (Shearer and DeBruyn 1986; but see Turner et al 1987). In principle, trophic interactions within the food web could lead to either increase or decrease phytoplankton and periphyton abundance, depending on whether predators or prey species are more strongly influenced by acidification events (e.g., Schindler et al 1985;France et al 1991;Appelberg et al 1993).…”

“…In principle, trophic interactions within the food web could lead to either increase or decrease phytoplankton and periphyton abundance, depending on whether predators or prey species are more strongly influenced by acidification events (e.g., Schindler et al 1985;France et al 1991;Appelberg et al 1993). Acidification also reduces the availability of dissolved inorganic carbon (DIC) and photosynthesis by periphyton (e.g., Turner et al 1994Turner et al , 1995aVinebrooke 1996). However, benthic biomass may not decline because severe acidification often leads to the development of loosely attached clouds of filamentous green algae (metaphyton) at pH Ͻ 5.2 (e.g., Turner et al 1987;Howell et al 1990).…”

“…Acidification also reduces the availability of dissolved inorganic carbon (DIC) and photosynthesis by periphyton (e.g., Turner et al 1994Turner et al , 1995aVinebrooke 1996). However, benthic biomass may not decline because severe acidification often leads to the development of loosely attached clouds of filamentous green algae (metaphyton) at pH Ͻ 5.2 (e.g., Turner et al 1987;Howell et al 1990).…”