Effects of Changes in Acidity on Aquatic Insects in Rocky Littoral Habitats of Lakes Near Sudbur y, Ontario

Abstract

Benthic aquatic insects were collected from rocky nearshore areas ( Ͻ 1 m deep) of 17 lakes near Sudbury, Ontario, with a pH range of 4.7-7.3 and a size range of less than 10 ha to over 10,000 ha. These insect communities were composed of taxa common to lake softsediments and streams. Direct and indirect effects of lake acidity appeared to be major controls on the structure of these communities, implying that several factors may be involved in restructuring during acidification or recovery. Declines in abundances of several taxa of Ephemeroptera at pH below 5.5 were attributable to acid toxicity, while increases in the abundances of Odonata and Diptera at pH below 5.5 were associated with the absence of fish predators and other indirect effects of acidity. The communities of two experimentally neutralized lakes restructured rapidly within 5 years, approaching but not achieving community structures typical of our near-neutral survey lakes. Neutralization led to recolonization or increased abundance of the acid-sensitive mayfly, Stenacron interpunctatum , and the dragonfly, Boyeria grafiana ; however, recolonization by other taxa expected to be present in nearneutral lakes ( Stenonema femoratum, Eurylophella, and Basiaeshna janata ) was not observed. Consistent with results for the survey lakes, declines in the abundances of the dragonflies Aeshna interrupta, Aeshna eremita , and Leucorrhinia glacialis in the neutralized lakes were associated with reintroductions of Salvelinus fontinalis (aurora trout) and increased fish predation pressure, while reduced abundances of the dipterans Ceratopogonidae, Psectrocladius , and Stackelbergina may be related to indirect effects of acidity other than fish predation. Although community composition varied greatly across the acidity gradient, total species richness and abundance were not correlated with lake chemistry or number of fish species.

Recovery of Crustacean Zooplankton Communities from Acidification in Killarney Park, Ontario, 1971–2000: pH 6 As a Recovery Goal

“…Post and Cucin (1984) showed that predation pressure on littoral benthic invertebrates by introduced yellow perch decreased biomass and body size in benthic invertebrate communities. Many other studies have shown the important interactions between fish and littoral benthic invertebrate communities (Diehl 1992, Carbone et al 1998, Sherwood et al 2002. Fish can be efficient predators and are important in structuring invertebrate communities in aquatic ecosystems ranging from streams (Wooster 1994, Nilsson et al 2008) to tropical reefs (Ayal andSafriel 1982, Dulvy et al 2004).…”

Macrozoobenthos structure in a temperate acid oligotrophic lake

“…In Jasne Lake, there were also relatively numerous taxa such as: Procladius sp., Ablabesmyia monilis, Cladopelma lateralis and Dicrotendipes sp. These taxa in significant densities also in acidic Canadian (Dermott et al, 1986;Carbone et al, 1998) and American lakes (Dougherty & Morgan, 1991) were found.…”

“…These organisms are also commonly found in other acid water bodies due to their resistance to low water pH (Carbone et al, 1998). The cited authors, studying the Canadian lakes, significantly higher densities of this group of animals in acidotrophic than in neutral lakes have noted.…”

“…However, some investigations did not show influence of water pH on the diversity and the number of zoobenthos taxa (Collins et al, 1981;Kownacki et al, 2000;Kownacki et al, 2006). Dougherty and Morgan (1991), as well as Carbone et al (1998) also reveal lack of overall changes in species richness and abundance related to acidity, although significant shifts in community composition occur.…”

“…The acidification of water bodies is a widespread phenomenon that has been extensively characterized in terms of chemical and biological changes (Carbone et al, 1998). The effect of acidification is, among other things, an increase in the solubility of aluminum, which is accompanied by the formation of toxic Al 3+ ions.…”