Mid-late Holocene changes in the El Niño Southern Oscillation and Hadley Cell intensity; their effect on sea-surface conditions in the mid-latitude southeast Pacific Ocean (41°S)

The study focuses on the observed effects of changes in the El Niño Southern Oscillation (ENSO) and Hadley Cell intensity on sea-surface water conditions in the SE Pacific (41°S; Site ODP1233) during the last 8.000 years. Recent studies suggest that periods characterised by a negative Southern Oscillation Index (SOI; El Niño) cause positive precipitation anomalies during austral winter (and annually) in Mid-South Chile, while austral summer periods are rather drier. This because El Niño weakens the southeast (SE) Pacific anticyclone, causing a northward shift of the westerly wind belt resulting in higher annual rainfall at 41°S. Positive rainfall anomalies result in a increasing runoff, which causes a decrease in sea-surface salinity (SSS) in near-shore areas. At first sight, this is supported by the process length of Operculodinium centrocarpum (a dinoflagellate cyst), which constitutes a proxy for a changing SSS/SST (sea-surface temperature)-ratio. A decreasing SSS and constant SST result in a shortening of the process lengths. However, when comparing the Fe-record of GeoB3313-1 with the intensity and frequency of the El Niño events during the studied period, a negative SOI seems not to be necessarily associated with positive annual rainfall anomalies in Mid-South Chile. Three major peaks in the frequency and intensity of El Niño events correspond with drier conditions at 41°S. Those three periods occur simultaneous with an increasing Hadley Cell activity, which in turn strengthens the SE Pacific anticyclone. This causes a southward shift of the westerlies, leading to dryer conditions at 41°S, in turn causing less runoff and an increase rather than a decrease in SSS. Thereby, negative SST anomalies occur offshore Mid-South Chile during the intensification of the SE Pacific anticyclone. Both the lower SST and higher SSS should result in longer process lengths while an obvious shortening is observed. Therefore, we suggest that the shortening of the process results from a further northward penetration of the less saline Chilean Fjord Waters. This is most likely caused by favourable southerly winds associated with a more poleward position of the SE Pacific anticyclone, due to an increase in intensity of the Hadley Cell. Those results indicate a domination of the Hadley Cell effects over the effects of ENSO in the mid-latitude SE Pacific Ocean

Holocene dinoflagellate cysts as salinity indicators from the southwestern Black Sea

Dinoflagellate cysts are used as a proxy for the reconstruction of the salinity variations during Holocene times in the southwestern Black Sea. Core GeoB 7625-2, located 50 km northeast of the mouth of the Sakarya River, was sampled with a 200 year resolution between 0.25 ka BP – 7.8 ka BP. In the lower part of the core, some extra crucial intervals were sampled with a higher resolution for the determination of the reconnection between the Black Sea and the Sea of Marmara. The drastic change in the dinoflagellate cyst assemblage – from a freshbrackish water to saltwater association – is observed between ~9.6 and ~8.1 ka BP, which is earlier than observed in the dinocyst studies of e.g. Marret et al. (in press), Mudie et al. (2001) and Wall & Dale (1973). This could indicate a diachronic salinification of the Black Sea. The fresh to brackish water indicator species are Spiniferites cruciformis form 1-4 and Pyxidinopsis psilata, while the most important saltwater species are Lingulodinium machaerophorum and cysts of Pentapharsodinium dalei. The first occurrence of euryhaline species took place synchronous with a sea level rise and an increase in productivity. The process length of L. machaerophorum, a salinity proxy, indicates a gradual salinity increase. This assumes a gradual reconnection between the Black Sea and the Sea of Marmara, which conflicts with the catastrophic flood (Noah’s Flood Hypothesis) introduced by Ryan et al. (1997, 2003). The 500 to 800 year cycles observed in the sedimentary record by Lamy et al. (2006), and related to the North Atlantic Oscillation, were not only recorded by us in the salinity proxy but also in dinoflagellate cyst abundances (productivity). The observed productivity changes are furthermore related to the sedimentation rate: the increase in precipitation in Anatolia possibly results in a higher sediment discharge leading to a better preservation of the organic-walled microfossils. This makes it difficult to determine whether the fluctuations of the dinocysts/gram ratio are the result of fluctuations in productivity or are an artefact due to changes in the sedimentation rate. Furthermore, it is shown that Peridinium ponticum, a species restricted geographically to the Black Sea, is a good proxy for the reconstruction of Holocene salinity variations since its relative abundance fluctuates synchronous with the process length variations of L. machaeorophorum

Invasive Alien Species in Belgian marine waters: an information platform and checklist for science and policy support

Since 2006, the ‘VLIZ Alien Species Consortium’ has collected data and information on species that were introduced by humans in marine and brackish habitats and have established reproducing populations in the study area. The consortium consists of a network of experts in marine and brackish environments in Belgium, representing more than 22 different institutions and supported by a secretariat hosted at Flanders Marine Institute VLIZ. Evidence on invasiveness is reported for 12 of the 73 alien species that are currently included in the checklist for the study area (October 2014). The network brings together scientific information from distributed sources in a central platform. It is a first step to developing an evidence-based approach to inform environmental policy objectives for Belgian marine waters and support effective measures to address invasive alien species in the study area. The information platform and species checklist are presented, approaches for collection and integration of information are described, and opportunities for collaboration between information systems at different governance levels are briefly discussed