Model simulation output data (CCSM3) related to uplift of African topography and the intensification of upwelling in the Benguela region

The Benguela Current, located off the west coast of southern Africa, is tied to a highly productive upwelling system**1. Over the past 12 million years, the current has cooled, and upwelling has intensified**2, 3, 4. These changes have been variously linked to atmospheric and oceanic changes associated with the glaciation of Antarctica and global cooling**5, the closure of the Central American Seaway**1, 6 or the further restriction of the Indonesian Seaway**3. The upwelling intensification also occurred during a period of substantial uplift of the African continent**7, 8. Here we use a coupled ocean-atmosphere general circulation model to test the effect of African uplift on Benguela upwelling. In our simulations, uplift in the East African Rift system and in southern and southwestern Africa induces an intensification of coastal low-level winds, which leads to increased oceanic upwelling of cool subsurface waters. We compare the effect of African uplift with the simulated impact of the Central American Seaway closure9, Indonesian Throughflow restriction10 and Antarctic glaciation**11, and find that African uplift has at least an equally strong influence as each of the three other factors. We therefore conclude that African uplift was an important factor in driving the cooling and strengthening of the Benguela Current and coastal upwelling during the late Miocene and Pliocene epochs.

Experiment on wound activated production of Prostaglandin E2 and related toxic compounds in populations of Gracilaria vermiculophylla

The capacity of the East Asian seaweed Gracilaria vermiculophylla ("Ogonori") for production of prostaglandin E2 from arachidonic acid occasionally causes food poisoning after ingestion. During the last two decades the alga has been introduced to Europe and North America. Non-native populations have been shown to be generally less palatable to marine herbivores than native populations. We hypothesized that the difference in palatability among populations could be due to differences in the algal content of prostaglandins. We therefore compared the capacity for wound-activated production of prostaglandins and other eicosatetraenoid oxylipins among five native populations in East Asia and seven non-native populations in Europe and NW Mexico, using a targeted metabolomics approach. In two independent experiments non-native populations exhibited a significant tendency to produce more eicosatetraenoids than native populations after acclimation to identical conditions and subsequent artificial wounding. Fourteen out of 15 eicosatetraenoids that were detected in experiment I and all 19 eicosatetraenoids that were detected in experiment II reached higher mean concentrations in non-native than in native specimens. The datasets generated in both experiments are contained in http://doi.pangaea.de/10.1594/PANGAEA.855008. Wounding of non-native specimens resulted on average in 390 % more 15-keto-PGE2, in 90 % more PGE2, in 37 % more PGA2 and in 96 % more 7,8-di-hydroxy eicosatetraenoic acid than wounding of native specimens. The dataset underlying this statement is contained in http://doi.pangaea.de/10.1594/PANGAEA.854847. Not only PGE2, but also PGA2 and dihydroxylated eicosatetraenoic acid are known to deter various biological enemies of G. vermiculophylla that cause tissue or cell wounding, and in the present study the latter two compounds also repelled the mesograzer Littorina brevicula. The dataset underlying this statement is contained in http://doi.pangaea.de/10.1594/PANGAEA.854922. Non-native populations of G. vermiculophylla are thus more defended against herbivory than native populations. This increased capacity for activated chemical defense may have contributed to their invasion success and at the same time it poses an elevated risk for human food safety.

Data compilation on the biological response to ocean acidification: environmental and experimental context of data sets and related literature

The exponential growth of studies on the biological response to ocean acidification over the last few decades has generated a large amount of data. To facilitate data comparison, a data compilation hosted at the data publisher PANGAEA was initiated in 2008 and is updated on a regular basis (doi:10.1594/PANGAEA.149999). By January 2015, a total of 581 data sets (over 4 000 000 data points) from 539 papers had been archived. Here we present the developments of this data compilation five years since its first description by Nisumaa et al. (2010). Most of study sites from which data archived are still in the Northern Hemisphere and the number of archived data from studies from the Southern Hemisphere and polar oceans are still relatively low. Data from 60 studies that investigated the response of a mix of organisms or natural communities were all added after 2010, indicating a welcomed shift from the study of individual organisms to communities and ecosystems. The initial imbalance of considerably more data archived on calcification and primary production than on other processes has improved. There is also a clear tendency towards more data archived from multifactorial studies after 2010. For easier and more effective access to ocean acidification data, the ocean acidification community is strongly encouraged to contribute to the data archiving effort, and help develop standard vocabularies describing the variables and define best practices for archiving ocean acidification data.

Model simulation output data (CCSM3) related to uplift of Africa and Himalaya/Tibet Plateau and the influence on tropical African vegetation

Hominid evolution in the late Miocene has long been hypothesized to be linked to the retreat of the tropical rainforest in Africa. One cause for the climatic and vegetation change often considered was uplift of Africa, but also uplift of the Himalaya and the Tibetan Plateau was suggested to have impacted rainfall distribution over Africa. Recent proxy data suggest that in East Africa open grassland habitats were available to the common ancestors of hominins and apes long before their divergence and do not find evidence for a closed rainforest in the late Miocene. We used the coupled global general circulation model CCSM3 including an interactively coupled dynamic vegetation module to investigate the impact of topography on African hydro-climate and vegetation. We performed sensitivity experiments altering elevations of the Himalaya and the Tibetan Plateau as well as of East and Southern Africa. The simulations confirm the dominant impact of African topography for climate and vegetation development of the African tropics. Only a weak influence of prescribed Asian uplift on African climate could be detected. The model simulations show that rainforest coverage of Central Africa is strongly determined by the presence of elevated African topography. In East Africa, despite wetter conditions with lowered African topography, the conditions were not favorable enough to maintain a closed rainforest. A discussion of the results with respect to other model studies indicates a minor importance of vegetation-atmosphere or ocean-atmosphere feedbacks and a large dependence of the simulated vegetation response on the land surface/vegetation model.