Summary1. The European Council Water Framework Directive requires reference conditions to be determined for all water body types including lakes. We examined the role of palaeolimnology, specifically the diatom record, as a tool for assessing eutrophication and for defining lake reference conditions and ecological status. 2. Sediment cores (representing c .  1850 to present day) were taken from 26 Scottish freshwater loch basins. Radiometric dating techniques ( 210 Pb and 137 Cs) established a chronology for each core. Two levels of diatom analysis were employed: a relatively high resolution (15-20 samples) at 21 lochs considered of high interest, and a lower resolution (four to five samples) at the remaining sites. 3. Detrended correspondence analysis and dissimilarity measures were applied to the core top (present day) and bottom (reference state, c .  1850) samples to assess floristic change at each site. Significant floristic change, indicative of nutrient enrichment, occurred in 18 lochs along a broad trophic gradient. 4. Two-way indicator species analysis (  ) was applied to the bottom ( c .  1850) samples to classify the 'reference' diatom assemblages and thereby characterize the reference floras of the different lake types.  identified four site end-groups, each with a characteristic diatom assemblage, although there was some overlap in the taxa present in the four groups. Water depth and productivity were key factors that explained the groupings. 5. Diatom transfer functions that reconstructed total phosphorus (TP) concentrations were used to evaluate eutrophication. Nineteen lochs had increases in diatom-inferred (DI) TP of > 5 µ g l − 1 (five of these > 20 µ g l − 1), six lochs had no change or negligible increases in DI-TP (< 2 µ g l − 1 ), and there was evidence of a decline in DI-TP in one loch over the period represented by the sediment cores. The inferred increases were significant at 12 lochs. 6. Synthesis and applications . Our data indicate that it may be difficult to find minimally impacted waters to act as reference sites, particularly for shallow, lowland lake types, in the current population. The derivation of site-specific reference conditions from the sediment record is a particularly valuable approach in such cases. Ordination, clustering and dissimilarity measures applied to palaeodata, combined with transfer functions, offer powerful techniques for characterizing lake types, defining ecological and chemical reference conditions, and assessing deviation from the reference state.

The estuary of the lower River Murray features a complex mosaic of lakes, coastal lagoons and interconnecting channels. The waters of these wetlands are degraded as a result of river regulation, water abstraction, salinisation, sedimentation and the recent constriction of the River mouth. Palaeolimnologial analysis of sediment cores in two wetlands reveals that salinity in the large terminal Lake Alexandrina was only moderately influenced by tidal inflow, particularly over the past ca. 2000 years. It is now largely fresh as a result of isolation by a series of barriers completed by 1940 AD. In contrast, the seaward portion of the Coorong, a back barrier coastal lagoon, was determined to be a subsaline estuary strongly influenced by marine inflows. These findings contrast somewhat with the Coorong's current Ramsar classification as a saline lagoon. Riverine diatoms, typical of the fossil flora of Lake Alexandrina, are rare or absent in the Holocene sediments of the Coorong, other than for a short period in the late Holocene in the northernmost end of the lagoon. The palaeolimnological evidence for independent evolution of these wetlands is consistent with geomorphic evidence of a stranded, last interglacial shoreline that acted as a sill limiting the exchange of flows between Lake Alexandrina and the Coorong lagoon.

Williams, M. A. J., Williams, F. M., Duller, G. A. T., Munro, R. H., El Tom, O. A. M., Barrows, T. T., Macklin, M. G., Woodward, J. C., Talbot, M. R., Haberlay, D., Fluin, J. (2010). Late Quaternary floods and droughts in the Nile valley, Sudan: new evidence from optically stimulated luminescence and AMS radiocarbon dating. Quaternary Science Reviews, 29(9-10), 1116-1137 Sponsorship: Australian Research Council;Our results show that the late Pleistocene Nile in northern Sudan was shifting position and actively aggrading at 145 +/- 20 kyr, 83 +/- 24 kyr, 32 +/- 8 kyr and 20.7 +/- 0.2 kyr and indicate, for the first time, a phase of high-energy flow in the White Nile at 27.8 +/- 3.2 kyr, with still high but somewhat reduced flow in that river at 13.3 kyr, 10 kyr and 4.8-4.0 kyr. Beach ridges associated with a 386 m strandline of the White Nile have OSL ages of 27.5 +/- 2.7 kyr and 14.5 +/- 1.6 kyr. The Holocene terraces and former channels of the main Nile have ages of 11 kyr, 6.5-5.0 kyr and 4.8-4.0 kyr, after which there was a general decline in flood discharge. The now arid main Nile valley in northern Sudan was significantly wetter during the early to middle Holocene, with a lake up to 450 km(2) in area, fed by an overflow channel from the early Holocene Nile between 9.5 kyr and 7.5 kyr. Previously stable late Pleistocene dunes were reactivated at intervals during the Holocene, with five samples from the White Nile valley indicating brief phases of Holocene dune activity at 9.9 +/- 2.0 kyr, 9.0 +/- 2.8 kyr, 6.6 +/- 0.9 kyr, 4.8 +/- 0.9 kyr and 2.9 +/- 0.5 kyr, the earliest of which occurred within periods of generally wetter climate and higher Nile flow. The youngest freshwater shells on the Khor Abu Habl alluvial fan west of the White Nile correspond to a time of regionally wetter climate between 1.7 and 1.0 kyr. Our results suggest that millennial scale climatic instability may have been characteristic of Holocene climates in this region. (C) 2010 Elsevier Ltd. All rights reserved.Peer reviewe

Epipelic diatom assemblages collected from three wetlands connected to the Murray River displayed considerable variation in response to flooding and drying phases. Murray River water input usually generated diatom assemblages dominated by Aulacoseira species. After isolation, the diatom flora of two wetlands shifted to assemblages of small Fragilariaceae forms. Elevated nutrient levels corresponded with the appearance of eutraphentic taxa such as Cyclotella meneghiniana, Eolimna subminuscula, Luticola mutica and Nitzschia palea. Further evapoconcentration induced shifts to taxa tolerant of elevated salinity levels including Amphora coffeaeformis, Navicula incertata, Staurophora salina and Tryblionella hungarica. Ordination analyses reveal a strong chemical control on the diatom taxa present in the wetlands, in accordance with known ecological preferences for salinity and nutrients. The influence of nitrogen and phosphorus concentrations in controlling diatom assemblages was subordinate to salinity once conductivity values exceeded 1400 μS cm–1. The results of such biomonitoring provide a means of interpreting wetland history from fossil assemblages contained in sediment sequences.

Over the last decade there has been a deliberate focus on the application of paleolimnological research to address issues of sediment flux and water quality change in the wetlands of the Murray-Darling Basin of Australia. This paper reports on the research outcomes on cores collected from sixteen wetlands along the Murrumbidgee-Murray River continuum. In all sixteen wetlands radiometric techniques and exotic pollen biomarkers were used to establish sedimentation rates from the collected cores. Fossil diatom assemblages were used to identify water source and quality changes to the wetlands. The sedimentation rates of all wetlands accelerated after European settlement, as little as two-fold, and as much as eighty times the mean rate through the Late Holocene. Some wetlands completely infilled through the Holocene, while others have rapidly progressed towards a terrestrial state due to accelerated accretion rates. Increasing wetland salinity and turbidity commenced within decades of settlement, contributing to sediment inputs. The sedimentation rate was observed to slow after river regulation in one wetland, but has accelerated recently in others. The complex history of flooding and drying, and wetland salinisation and eutrophication, influence the reliability of models used to establish recent, fine-resolution chronologies with confidence and the capacity to attribute causes to documented effects.