{"name":"aquatic-community-response-in-a-groundwater-fed-desert-lake-to-holocene-desiccation-of-the-sahara","title":"Aquatic community response in a groundwater-fed desert lake to Holocene desiccation of the Sahara","maintainer":"Christian Schepers","maintainer_email":"christian_schepers@online.de","notes":"The finely laminated sediment record of a permanent, hypersaline, desert oasis lake in the Ounianga region of northeastern Chad presents a unique opportunity to document the hydrological evolution of this groundwater-fed aquatic ecosystem during mid- and late-Holocene desiccation of the Sahara. In this study we reconstruct long-term changes in zoobenthos and zooplankton communities of Lake Yoa as their early-Holocene freshwater habitat changed into the hypersaline conditions prevailing today. Chironomid production peaked during the fresh-to-saline transition period, then stabilized at about half\r\nthat of the earlier freshwater ecosystem. Quantitative salinity inferences based on fossil chironomid assemblages indicate that the fresh-to-saline transition occurred fairly abruptly between w4100 and 3400 cal yr BP, but that the ecosystem was buffered against shorter-term climate fluctuations due to continuous inflow of fossil groundwater. The mixture of tropical-African and southern Palaearctic chironomid faunas in the Lake Yoa fossil record required us to address several methodological issues concerning chironomid-based salinity reconstruction, and the applicability of a calibration dataset based on tropical East and West African lakes to this Sahara desert locality. The most coherent reconstruction\r\nwas obtained with an inference model that applies a weighted best-modern-analogue (WMAT) transfer function to the African calibration dataset expanded with six Sahara lakes.","type":"researchdata","resources":[{"description":"","format":"PDF","url":"http://crc806db.uni-koeln.de/data/Phase_1/A/A2/data/000/Eggermont_etal_2008_Aquatic_community_response_groundwater-fed_desert_lake_Holocene_desiccation_Sahara.pdf","created":"2017-10-06T19:04:08.778992","state":"active","package_id":"78a2b393-582c-4429-b2af-7237df64c50b","last_modified":"2021-10-23T04:10:08","id":"c6856575-6e3e-40c8-8fe6-da91808c4bfd","name":"Eggermont_etal_2008_Aquatic_community_response_groundwater-fed_desert_lake_Holocene_desiccation_Sahara.pdf"},{"description":"","format":"URL","url":"http://www.sciencedirect.com/science/article/pii/S0277379108002151","created":"2017-10-06T19:04:09.464320","state":"active","package_id":"78a2b393-582c-4429-b2af-7237df64c50b","last_modified":"2021-10-23T04:10:08","id":"44fb2e2c-75d3-4525-a670-498057b85645","name":"http://www.sciencedirect.com/science/article/pii/S0277379108002151"}],"tags":[{"name":"aquatic ecosystem"},{"name":"chad"},{"name":"desert lake"},{"name":"ecosystem succession"},{"name":"groundwater fed"},{"name":"holocene"},{"name":"lake sediments"},{"name":"lake yoa"},{"name":"qunianga"},{"name":"sahara"}],"extras":[{"key":"bibtex:address","value":""},{"key":"bibtex:author","value":"Hilde Eggermont and Dirk Verschuren and Maureen Fagot and Bob Rumes and Bert Van Bocxlaer and Stefan Kr\u00f6pelin"},{"key":"bibtex:booktitle","value":""},{"key":"bibtex:citation","value":"Eggermont H., Verschuren D., Fagot M., Rumes B., Bocxlaer B. V., Kr\u00f6pelin S. (2008): Aquatic community response in a groundwater-fed desert lake to Holocene desiccation of the Sahara. In: Quaternary Science Reviews 27, Issues 25\u201326: 2411-2425"},{"key":"bibtex:doi","value":"10.1016/j.quascirev.2008.08.028"},{"key":"bibtex:editor","value":""},{"key":"bibtex:howpublished","value":""},{"key":"bibtex:isbn","value":""},{"key":"bibtex:journal","value":"Quaternary Science Reviews"},{"key":"bibtex:month","value":""},{"key":"bibtex:number","value":""},{"key":"bibtex:organization","value":""},{"key":"bibtex:pages","value":"2411\u20132425"},{"key":"bibtex:publisher","value":""},{"key":"bibtex:school","value":""},{"key":"bibtex:series","value":""},{"key":"bibtex:type","value":"article"},{"key":"bibtex:key","value":""},{"key":"bibtex:url","value":""},{"key":"bibtex:volume","value":"27"},{"key":"bibtex:year","value":"2008"},{"key":"Spatial","value":"{\"type\":\"Point\",\"coordinates\":[20.51,19.01]}"}],"groups":[{"image_url":"http://crc806db.uni-koeln.de/fileadmin/template/images/projects/imageA2.png","name":"a2"}],"author":" Christian Schepers","author_email":false}{"help":"Update a dataset (package).\n\n You must be authorized to edit the dataset and the groups that it belongs\n to.\n\n Plugins may change the parameters of this function depending on the value\n of the dataset's ``type`` attribute, see the ``IDatasetForm`` plugin\n interface.\n\n For further parameters see ``package_create()``.\n\n :param id: the name or id of the dataset to update\n :type id: string\n\n :returns: the updated dataset (if 'return_package_dict' is True in the\n context, which is the default. Otherwise returns just the\n dataset id)\n :rtype: dictionary\n\n ","success":false,"error":{"message":"Unable to add package to search index: Solr returned an error: 500 Lock obtain timed out: NativeFSLock@\/var\/lib\/solr\/data\/index\/lucene-d6f7b3bf6fe64f362b4d45bfd4924f54-write.lock org.apache.lucene.store.LockObtainFailedException: Lock obtain timed out: NativeFSLock@\/var\/lib\/solr\/data\/index\/lucene-d6f7b3bf6fe64f362b4d45bfd4924f54-write.lock \tat org.apache.lucene.store.Lock.obtain(Lock.java:85) \tat org.apache.lucene.index.IndexWriter.init(IndexWriter.java:1562) \tat org.apache.lucene.index.IndexWriter.(IndexWriter.java:1418) \tat org.apache.solr.update.SolrIndexWriter.(SolrIndexWriter.java:191) \tat org.apache.solr.update.UpdateHandler.createMainIndexWriter(UpdateHandler.java:98) \tat org.apache.solr.update.DirectUpdateHandler2.openWriter(DirectUpdateHandler2.java:173) \tat org.apache.solr.update.DirectUpdateHandler2.addDoc(DirectUpdateHandler2.java:220) \tat org.apache.solr.update.processor.RunUpdateProcessor.processAdd(RunUpdateProcessorFactory.java:61) \tat org.apache.solr.handler.XMLLoader.processUpdate(XMLLoader.java:139) \tat org.apache.solr.handler.XMLLoader.load(XMLLoader.java:69) \tat org.apache.solr.handler.ContentStreamHandlerBase.handleRequestBody(ContentStreamHandlerBase.java:54) \tat org.apache.solr.handler.RequestHandlerBase.handleRequest(RequestHandlerBase.java:131) \tat org.apache.solr.core.SolrCore.execute(SolrCore.java:1317) \tat org.apache.solr.servlet.SolrDispatchFilter.execute(SolrDispatchFilter.java:338) \tat org.apache.solr.servlet.SolrDispatchFilter.doFilter(SolrDispatchFilter.java:241) \tat org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157) \tat org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:388) \tat org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:216) \tat org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:182) \tat org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:766) \tat org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:418) \tat org.mortbay.jetty.handler.ContextHandlerCollection.handle(ContextHandlerCollection.java:230) \tat or - \n\n\nError 500 Lock obtain timed out: NativeFSLock@\/var\/lib\/solr\/data\/index\/lucene-d6f7b3bf6fe64f362b4d45bfd4924f54-write.lock\n\norg.apache.lucene.store.LockObtainFailedException: Lock obtain timed out: NativeFSLock@\/var\/lib\/solr\/data\/index\/lucene-d6f7b3bf6fe64f362b4d45bfd4924f54-write.lock\n\tat org.apache.lucene.store.Lock.obtain(Lock.java:85)\n\tat org.apache.lucene.index.IndexWriter.init(IndexWriter.java:1562)\n\tat org.apache.lucene.index.IndexWriter.<init>(IndexWriter.java:1418)\n\tat org.apache.solr.update.SolrIndexWriter.<init>(SolrIndexWriter.java:191)\n\tat org.apache.solr.update.UpdateHandler.createMainIndexWriter(UpdateHandler.java:98)\n\tat org.apache.solr.update.DirectUpdateHandler2.openWriter(DirectUpdateHandler2.java:173)\n\tat org.apache.solr.update.DirectUpdateHandler2.addDoc(DirectUpdateHandler2.java:220)\n\tat org.apache.solr.update.processor.RunUpdateProcessor.processAdd(RunUpdateP","__type":"Search Index Error"}}