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Veröffentlichung Decades needed for ecosystem components to respond to a sharp and drastic phosphorus load reduction(2020) Beulker, Camilla; Köhler, Antje; Chorus, Ingrid; Fastner, JuttaLake Tegel is an extreme case of restoration: inflow treatment reduced its main external phosphorus (TP) load 40-fold, sharply focused in time, and low-P water flushed the lake volume ~ 4 times per year. We analysed 35 years of data for the time TP concentrations took to decline from ~ 700 to 20-30 (my)g/l, biota to respond and cyanobacteria to become negligible. The internal load proved of minor relevance. After 10 years, TP reached 35-40 (my)g/l, phytoplankton biomass abruptly declined by 50% and cyanobacteria no longer dominated; yet 10 years later at TP < 20-30 (my)g/l they were below quantifiable levels. 20-25 years after load reduction, the lake was stably mesotrophic, macrophytes had returned down to 6-8 m, and vivianite now forms, binding P insolubly in the sediment. Bottom-up control of phytoplankton through TP proved decisive. Five intermittent years with a higher external P load caused some 're-eutrophication', delaying recovery by 5 years. While some restoration responses required undercutting thresholds, particularly that of phytoplankton biomass to TP, resilience and hysteresis proved irrelevant. Future research needs to focus on the littoral zone, and for predicting time spans for recovery more generally, meta-analyses should address P load reduction in combination with flushing rates. The Author(s) 2020Veröffentlichung Colonisation of secondary habitats in mining sites by Labidura riparia (Dermaptera: Labiduridae) from multiple natural source populations(2021) Wiegleb, Gerhard; Güth, Mareike; Durka, WalterAbstract Background Open cast lignite mines, sand pits and military training areas represent human-made, secondary habitats for specialized xerothermophilous and psammophilous species. Rare species, including the earwig Labidura riparia, are found in high population densities in such sites. However, it is unknown from which sources colonisation took place and how genetic variation compares to that of ancient populations on natural sites. Methods Using nine microsatellite markers, we analysed genetic variation and population structure of L. riparia in 21 populations in NE Germany both from secondary habitats such as lignite-mining sites, military training areas and a potassium mining heap, and rare primary habitats, such as coastal and inland dunes. Results Genetic variation was higher in populations from post-mining sites and former military training areas than in populations from coastal or inland dune sites. Overall population diferentiation was substantial (FST=0.08; F'ST=0.253), with stronger diferentiation among primary (FST=0.196; F'ST=0.473) than among secondary habitats (FST=0.043; F'ST=0.147). Diferentiation followed a pattern of isolation by distance. Bayesian structure analysis revealed three gene pools representing primary habitats on a coastal dune and two diferent inland dunes. All populations from secondary habitats were mixtures of the two inland dune gene pools, suggesting multiple colonization of post-mining areas from diferent source populations and hybridisation among source populations. Discussion Populations of L. riparia from primary habitats deserve special conservation, because they harbour diferentiated gene pools. The majority of the L. riparia populations, however, thrive in secondary habitats, highlighting their role for conservation. Implications for insect conservation A dual strategy should be followed of conserving both remaining natural habitat harbouring particular intraspecific gene pools and secondary habitat inhabited by large admixed and genetically highly variable populations. © The Author(s) 2021