Local Factors and Colonist Dispersal Influence Crustacean Zooplankton Recovery From Cultural Acidification

Abstract

We investigated the roles of local environmental conditions and dispersal limitation in zooplankton recovery from acidification in Swan Lake, Ontario, a historically acidified, metal‐contaminated lake. We hypothesized that local environmental conditions (pH and the presence of resident, acid‐tolerant zooplankton) would limit the establishment of several zooplankton colonist species. We tested this in a factorial mesocosm experiment that ran for 32 days during the mid summer. Ambient pH (5.6) reduced the abundance of two acid‐sensitive cladoceran taxa, Daphnia spp. and Ceriodaphnia lacustris compared to elevated pH (6.5) but increased the abundance of cyclopoid copepod juveniles. The resident community suppressed Skistodiaptomus oregonensis and Diacyclops bicuspidatus thomasi, and to a lesser extent Mesocyclops edax, but slightly enhanced Daphnia spp. We also hypothesized that conditions in the sediments of acidified Swan Lake would limit zooplankton recruitment from diapausing eggs. We tested this by reciprocally transferring sediments containing eggs between Swan Lake and a nearby recovered lake, and incubating them for 15 weeks in 20‐L emergence traps. Most zooplankton emerged from diapause in both lakes indicating that this mechanism contributes to the recolonization of acidified lakes once pH returns to normal. Some species, however, emerged in only one lake or the other, indicating that hatching cues such as light, temperature, oxygen, or appropriate pH may have been missing. Our experiments demonstrate that both local lake conditions and diapausing eggs can influence zooplankton recovery. Continued recovery may require additional management efforts to reduce and control regional acid emissions and active intervention in the form of food web manipulations.

Immigration and zooplankton community responses to nutrient enrichment: a mesocosm experiment

“…Also, the occasional success of adult colonists in this study and others (e.g. Binks et al 2005) shows that colonisation by mature zooplankton is possible. Further experiments involving the addition of colonists to enclosures with and without resident zooplankton would be necessary to determine whether biotic factors (i.e.…”

Recovery of zooplankton diversity in a restored Mediterranean temporary marsh in Doñana National Park (SW Spain)

“…Predation and competition are likely to have important effects on the zooplankton community composition in new ponds. It is possible that competition with species that established populations early on delayed colonization by other species present in nearby source populations, just as acidtolerant species established in acidified lakes delay the recovery of acid-sensitive species after restoration of normal pH (Binks et al, 2005;Frost et al, 2006). However, little is known about the interactions between the species recorded in this study.…”

Portage connectivity does not predict establishment success of canoe-mediated dispersal for crustacean zooplankton

“…Biological resistance could also play a role by preventing establishment in an otherwise hospitable environment. For instance, priority effects can allow the resident zooplankton community to inhibit further colonization through resource monopolization (Boileau et al 1992;Lukaszewski et al 1999;Shurin 2000;De Meester et al 2002;Binks et al 2005). Predation by macroinvertebrates has also been shown to significantly reduce zooplankton abundance, diversity, and species richness in some acid-recovering lakes (Arnott et al 2006) and can play a role in restricting colonization when fish are not present (Arnott and Vanni 1993; but see Shurin 2001).…”

“…Several studies have identified a number of local exclusion mechanisms at work even in the face of frequent dispersal, including biological resistance from native and non-native predatory macroinvertebrates (Arnott and Vanni 1993;Keller et al 2002;Arnott et al 2006;Strecker and Arnott 2010) and competitive interactions with the resident zooplankton community (Lukaszewski et al 1999;Shurin 2000;De Meester et al 2002;Binks et al 2005). Moreover, dispersal is often haphazard in the sense that only a few colonists are likely to disperse to the same location at any one time, making small colonist populations vulnerable to extinction via Allee effects (Stephens et al 1999;Kramer et al 2008).…”