TY - JOUR A1 - Pätzig, Marlene A1 - Kalettka, Thomas A1 - Onandia, Gabriela A1 - Balla, Dagmar A1 - Lischeid, Gunnar T1 - How much information do we gain from multiple-year sampling in natural pond research? JF - Limnologica : ecology and management of inland waters N2 - Natural ponds are perceived as spatially and temporally highly variable ecosystems. This perception is in contrast to the often-applied sampling design with high spatial but low temporal replication. Based on a data set covering a period of six years and 20 permanently to periodically inundated ponds, we investigated whether this widely applied sampling design is sufficient to identify differences between single ponds or single years with regard to water quality and macrophyte community composition as measures of ecosystem integrity. In our study, the factor "pond", which describes differences between individual ponds, explained 56 % and 63 %, respectively, of the variance in water quality and macrophyte composition. In contrast, the factor "year" that refers to changes between individual years, contributed less to understand the observed variability in water quality and macrophyte composition (10 % and 7 % respectively, of the variance explained). The low explanation of variance for "year" and the low year-to-year correlation for the single water quality parameter or macrophyte coverage values, respectively, indicated high but non-consistent temporal variability affecting individual pond patterns. In general, the results largely supported the ability of the widely applied sampling strategy with about one sampling date per year to capture differences in water quality and macrophyte community composition between ponds. Hence, future research can be rest upon sampling designs that give more weight to the number of ponds than the number of years in dependence on the research question and the available resources. Nonetheless, pond research would miss a substantial amount of information (7 to 10 % of the variance explained), when the sampling would generally be restricted to one year. Moreover, we expect that the importance of multiple-year sampling will likely increase in periods and regions of higher hydrological variability compared to the average hydrological conditions encountered in the studied period. KW - water quality KW - macrophytes KW - space KW - time KW - kettle holes KW - conservation Y1 - 2020 U6 - https://doi.org/10.1016/j.limno.2019.125728 SN - 0075-9511 SN - 1873-5851 VL - 80 PB - Elsevier CY - Amsterdam [u.a.] ER - TY - JOUR A1 - Périllon, Cécile A1 - Pöschke, Franziska A1 - Lewandowski, Jörg A1 - Hupfer, Michael A1 - Hilt, Sabine T1 - Stimulation of epiphyton growth by lacustrine groundwater discharge to an oligo-mesotrophic hard-water lake JF - Freshwater Science N2 - Periphyton is a major contributor to aquatic primary production and often competes with phytoplankton and submerged macrophytes for resources. In nutrient-limited environments, mobilization of sediment nutrients by groundwater can significantly affect periphyton (including epiphyton) development in shallow littoral zones and may affect other lake primary producers. We hypothesized that epiphyton growth in the littoral zone of temperate oligomesotrophic hard-water lakes could be stimulated by nutrient (especially P) supply via lacustrine groundwater discharge (LGD). We compared the dry mass, chlorophyll a (chl a), and nutrient content of epiphyton grown on artificial substrates at different sites in a groundwater-fed lake and in experimental chambers with and without LGD. During the spring-summer periods, epiphyton accumulated more biomass, especially algae, in littoral LGD sites and in experimental chambers with LGD compared to controls without LGD. Epiphyton chl a accumulation reached up to 46 mg chl a/m(2) after 4 wk when exposed to LGD, compared to a maximum of 23 mg chl a/m(2) at control (C) sites. In the field survey, differences in epiphyton biomass between LGD and C sites were most pronounced at the end of summer, when epilimnetic P concentrations were lowest and epiphyton C:P ratios indicated P limitation. Groundwater-borne P may have facilitated epiphyton growth on macrophytes and periphyton growth on littoral sediments. Epiphyton stored up to 35 mg P/m(2) in 4 wk (which corresponds to 13% of the total P content of the littoral waters), preventing its use by phytoplankton, and possibly contributing to the stabilization of a clear-water state. However, promotion of epiphyton growth by LGD may have contributed to an observed decline in macrophyte abundance caused by epiphyton shading and a decreased resilience of small charophytes to drag forces in shallow littoral areas of the studied lake in recent decades. KW - lacustrine groundwater discharge KW - periphyton KW - littoral KW - nutrients KW - benthic KW - macrophytes KW - seepage Y1 - 2017 U6 - https://doi.org/10.1086/692832 SN - 2161-9549 SN - 2161-9565 VL - 36 SP - 555 EP - 570 PB - Univ. of Chicago Press CY - Chicago ER - TY - JOUR A1 - Darwall, William A1 - Bremerich, Vanessa A1 - De Wever, Aaike A1 - Dell, Anthony I. A1 - Freyhof, Joerg A1 - Gessner, Mark O. A1 - Grossart, Hans-Peter A1 - Harrison, Ian A1 - Irvine, Ken A1 - Jähnig, Sonja C. A1 - Jeschke, Jonathan M. A1 - Lee, Jessica J. A1 - Lu, Cai A1 - Lewandowska, Aleksandra M. A1 - Monaghan, Michael T. A1 - Nejstgaard, Jens C. A1 - Patricio, Harmony A1 - Schmidt-Kloiber, Astrid A1 - Stuart, Simon N. A1 - Thieme, Michele A1 - Tockner, Klement A1 - Turak, Eren A1 - Weyl, Olaf T1 - The alliance for freshwater life BT - a global call to unite efforts for freshwater biodiversity science and conservation JF - Aquatic Conservation: Marine and Freshwater Ecosystems N2 - 1. Global pressures on freshwater ecosystems are high and rising. Viewed primarily as a resource for humans, current practices of water use have led to catastrophic declines in freshwater species and the degradation of freshwater ecosystems, including their genetic and functional diversity. Approximately three-quarters of the world's inland wetlands have been lost, one-third of the 28 000 freshwater species assessed for the International Union for Conservation of Nature (IUCN) Red List are threatened with extinction, and freshwater vertebrate populations are undergoing declines that are more rapid than those of terrestrial and marine species. This global loss continues unchecked, despite the importance of freshwater ecosystems as a source of clean water, food, livelihoods, recreation, and inspiration. 2. The causes of these declines include hydrological alterations, habitat degradation and loss, overexploitation, invasive species, pollution, and the multiple impacts of climate change. Although there are policy initiatives that aim to protect freshwater life, these are rarely implemented with sufficient conviction and enforcement. Policies that focus on the development and management of fresh waters as a resource for people almost universally neglect the biodiversity that they contain. 3. Here we introduce the Alliance for Freshwater Life, a global initiative, uniting specialists in research, data synthesis, conservation, education and outreach, and policymaking. This expert network aims to provide the critical mass required for the effective representation of freshwater biodiversity at policy meetings, to develop solutions balancing the needs of development and conservation, and to better convey the important role freshwater ecosystems play in human well-being. Through this united effort we hope to reverse this tide of loss and decline in freshwater biodiversity. We introduce several short- and medium-term actions as examples for making positive change, and invite individuals, organizations, authorities, and governments to join the Alliance for Freshwater Life. KW - biodiversity KW - conservation evaluation KW - endangered species KW - fish KW - invertebrates KW - macrophytes Y1 - 2018 U6 - https://doi.org/10.1002/aqc.2958 SN - 1052-7613 SN - 1099-0755 VL - 28 IS - 4 SP - 1015 EP - 1022 PB - Wiley CY - Hoboken ER - TY - JOUR A1 - Brothers, Soren M. A1 - Hilt, Sabine A1 - Meyer, Stephanie A1 - Köhler, Jan T1 - Plant community structure determines primary productivity in shallow, eutrophic lakes JF - Freshwater biology N2 - Regime shifts are commonly associated with the loss of submerged macrophytes in shallow lakes; yet, the effects of this on whole-lake primary productivity remain poorly understood. This study compares the annual gross primary production (GPP) of two shallow, eutrophic lakes with different plant community structures but similar nutrient concentrations. Daily GPP rates were substantially higher in the lake containing submerged macrophytes (58623gCm(-2)year(-1)) than in the lake featuring only phytoplankton and periphyton (40823gCm(-2)year(-1); P<0.0001). Comparing lake-centre diel oxygen curves to compartmental estimates of GPP confirmed that single-site oxygen curves may provide unreliable estimates of whole-lake GPP. The discrepancy between approaches was greatest in the macrophyte-dominated lake during the summer, with a high proportion of GPP occurring in the littoral zone. Our empirical results were used to construct a simple conceptual model relating GPP to nutrient availability for these alternative ecological regimes. This model predicted that lakes featuring submerged macrophytes may commonly support higher rates of GPP than phytoplankton-dominated lakes, but only within a moderate range of nutrient availability (total phosphorus ranging from 30 to 100gL(-1)) and with mean lake depths shallower than 3 or 4m. We conclude that shallow lakes with a submerged macrophyte-epiphyton complex may frequently support a higher annual primary production than comparable lakes that contain only phytoplankton and periphyton. We thus suggest that a regime shift involving the loss of submerged macrophytes may decrease the primary productivity of many lakes, with potential consequences for the entire food webs of these ecosystems. KW - macrophytes KW - oxygen curves KW - periphyton KW - regime shift KW - trophic status Y1 - 2013 U6 - https://doi.org/10.1111/fwb.12207 SN - 0046-5070 VL - 58 IS - 11 SP - 2264 EP - 2276 PB - Wiley-Blackwell CY - Hoboken ER -