Late Holocene Indian summer monsoon variability revealed from a 3,300-year-long 1 lake sediment record from Nir'pa Co, southeastern years. Constrained by modern calibration elevated silt and lithics and low sand and clay 24 between 3.3-2.4 ka and 1.3 ka to the present indicate two pluvial phases with lake levels 25 near their current overflow elevation. Between 2.4-1.3 ka, a sharp increase in sand and 26 corresponding decrease in lithics and silt suggest drier conditions and lower lake levels at 27Nir'pa Co. Hydroclimate expressions in the sedimentological proxies during the 28Medieval Climate Anomaly (MCA) and Little Ice Age (LIA) are not statistically 29 significant, suggesting that these events were minor compared to the millennial scale 30 variability on which they were superimposed. However, decreasing sand and increasing 31 lithics and silt during the MCA between 950-800 cal yr B.P. may suggest briefly wetter 32 conditions while increasing sand and reduced lithics and silt from 500-200 cal yr B.P. an area referred to as the Third Pole Environment (Qiu, 2008), show that the Indian 47 summer monsoon (ISM) reached a maximum during the early and middle Holocene 48 between 10 and approximately 6 ka when boreal summer insolation peaked and strong 49 tropical Pacific sea surface temperature (SST) gradients resembled a La Niña-like mean 50 state (Koutavas et al., 2006;He et al., 2004;Bird et al., 2014;Cai et al., 2012; Yanhong 51 et al., 2006;Marchitto et al., 2010;Morrill et al., 2003). The late Holocene, in contrast, 52 has been characterized by increasing aridity as summer insolation waned and an 53 increasingly El Niño-like mean state developed in the tropical Pacific. Despite an 54 improved understanding of long-term Holocene ISM trends and the likely driving 55 mechanisms, higher frequency ISM variations have been more difficult to characterize 56 because there are comparatively few high-resolution records from the Third Pole (Chen et 57 al., 2015). The late Holocene is under represented by high-resolution paleoclimate 58 records in part because mean state aridity resulted in decreased resolution (e.g., Bird et 59 al., 2014) or depositional hiatuses in many ISM archives (Berkelhammer et al., 2012; 60 Morrill et al., 2006;Cai et al., 2012). The paucity of climate records detailing ISM 61 variability during the last few millennia limits our understanding of monsoon dynamics 62 during a time when climatic boundary conditions were generally similar to the present, 63 but perturbations in radiative and other forcings, including ocean-atmosphere processes, 64 produced widely recognized climatic events including: the Medieval Climate Anomaly 65 (MCA; 950-1250 AD) and Little Ice Age (LIA; 1450-1900 AD) (Mann et al., 2009). 66Paleoclimate records from the Third Pole that span at least part of the late 67Holocene suggest that within this period of general aridity there were regional scale 68Bird et al. (2016) Page 4 of 39 fluctuations in ISM precipitation, lake levels and temperature (Bird et al., 2014; 69 ...

Taking into account the continuous increase in freshwater introductions, and to support the recent European legislation on invasive alien species, the identification of priority pathways and gateways of introductions is of utmost importance to develop adequate control strategies. The aim of this paper was to analyse the main pathways and gateways of introductions of freshwater alien species in Europe. Based on a thorough review of the scientific and grey literature, information on pathways, country and year of initial introduction of all freshwater alien species in Europe, was retrieved. The spatial and temporal patterns and trends of biological invasions in freshwater ecosystems in Europe, in relation to different pathways, were assessed. Our results pinpoint the major importance of aquaculture, pet/aquarium trade and stocking activities as pathways of introduction of freshwater alien species in Europe. For species native to some European countries, shipping and inland canals were the most important pathways, highly responsible for the entry of many harmful species. Germany, the United Kingdom and Italy were the main entry gateways of freshwater alien species in Europe. We found a geographical pattern related to some pathways of introduction in Europe: introductions through inland canals were concentrated in Central/North-eastern Europe, while introductions through pet/terrarium/aquarium trade were mainly observed in Central/Western Europe. While Chordata species entered Europe mainly through the three major above mentioned pathways, many harmful Arthropoda and Mollusca entered through shipping and inland canals. The information gathered in this study clearly indicates the entry routes that should be prioritised by Member States, for which stronger control and management actions should be implemented and prevention efforts concentrated under the scope of the related new EU Regulation.

Hypoxia, low dissolved oxygen (DO) concentrations (<2 mg/L), has been a major issue in Lake Erie for decades. While much emphasis has been placed on biological factors, particularly algal blooms, contributing to hypolimnetic oxygen depletion, there has been little focus on the role of weather. For this study, we monitored water temperature and DO concentrations at sites in the western, central, and Sandusky basins in Lake Erie during June and July 2010-2012. We then compared trends in stratification and DO concentrations to weather patterns during that period. We found that during those three years, there was significant variation in weather patterns, particularly decreased ice coverage and increased storm events in 2012. These weather patterns corresponded to 2012 having the warmest water temperatures, some of the lowest DO concentrations, and a deeper and thinner hypolimnion (especially in the central basin) than the previous years. We found a relationship between weather and hypoxia, providing further evidence for why these basins are susceptible to low DO conditions during summer months. The role of weather in hypoxia is another indication that the lake is vulnerable to effects of climate change and should be considered in management strategies.

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