Long-term studies of crayfish-invaded lakes reveal limited potential for macrophyte recovery from the seed bank

Habitat explains patterns of population decline for an invasive crayfish

“…Hansen et al (2013a) recorded significant recovery of native fish, crayfish, and macrophytes in Sparkling Lake where F. rusticus was manually removed, but found little to no recovery of some benthic macroinvertebrates in this lake. Alternatively, Baldridge and Lodge (2014) working in a subset of the study lakes reported here found that the seed banks remaining after F. rusticus invasion were not generally adequate for recovery of aquatic macrophytes even if this invader declined, and that active restoration of macrophytes may be required. Loss of the aquatic macrophyte seed bank in lakes that achieve high F. rusticus abundances could explain a lack of oscillating boom-bust dynamics between crayfish and aquatic macrophytes, and is consistent with expectations that depletion of pooled resources can contribute to invasive species population declines (Strayer et al 2017).…”

Response of Submerged Macrophyte Communities to External and Internal Restoration Measures in North Temperate Shallow Lakes

“…Whether and which macrophyte stands or propagules survive during the turbid phase depends on the occurrence of macrophyte species before the shift to turbid conditions and on the length and severity of the turbid phase (e.g., Vari and Toth 2017). Seed banks in shallow lake sediments have often been assumed to be insufficient for recovery of submerged vegetation by germination, due to low numbers of viable seedlings, strong seed dormancy, strict germination cues and the reliance of many species upon vegetative reproduction (Haag, 1983 ; Kautsky, 1990 ; Rodrigo et al, 2013 ; Baldridge and Lodge, 2014 ). In contrast, De Winton et al ( 2000 ) and Verhofstad et al ( 2017 ) have shown that seed banks from even the most degraded lakes are capable of an emergence response and thus offer a potential means to restore vegetation.…”

Long‐term macrophyte and snail community responses to population declines of invasive rusty crayfish (Faxonius rusticus)

“…Between 1975 and 2020, each of our 10 study lakes was sampled for crayfishes between 9 and 17 times using standard methods for our study system (Table 1; Baldridge & Lodge, 2014; Capelli & Magnuson, 1983; Kreps et al, 2012; Larson et al, 2019). Wire‐mesh Gee minnow traps with two 3.5 cm diameter openings were baited with ~120 g of beef liver and set overnight at depths of 1–3 m. Each lake was sampled at either 24 or 36 sites, located at least 100 m apart, to allow for 12 traps per major habitat type present in the lake (cobble, open sand, or macrophyte; Kershner & Lodge, 1995, Lodge et al, 1998).…”

“…We sampled macrophytes, snails, and crayfishes in 10 F. rusticus‐ invaded and uninvaded lakes (Table 1) between late June and early September of 1987, 2002, 2011, and 2020. Subsets of the 1987, 2002, and 2011 data were previously used in other publications but were never published in a data repository (Baldridge, 2013; Baldridge & Lodge, 2014; Kreps et al, 2012; Lodge et al, 1998; Olsen, 1989; Rosenthal, 2004). Data from 2020 are original to this study.…”

“…Several previous studies in northern Wisconsin lakes have examined whether freshwater communities and ecosystems can recover after either natural or human‐caused declines in F. rusticus populations. Baldridge and Lodge (2014) found that macrophytes in lakes invaded by F. rusticus had only a modest potential for future recovery due to depleted seed banks compared to uninvaded lakes, suggesting that active restoration of lakes might be necessary for recovery of macrophyte communities after F. rusticus declines (e.g., Kettenring & Tarsa, 2020). Conversely, Hansen, Hein, et al (2013) demonstrated that manual removal of F. rusticus from a small lake resulted in substantial recovery of macrophytes, but found no recovery of benthic macroinvertebrates, perhaps because the recovery of fish populations suppressed invertebrate response.…”