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As one of Earth's most productive marine ecosystems, the Peruvian upwelling system transports large amounts of biogenic matter from the surface to the deep ocean. Whilst particle sinking velocity is a key factor controlling the biological pump, thereby affecting carbon sequestration and O2-depletion, it has not yet been measured in this system. During a 50 d mesocosm experiment in the surface waters off the coast of Peru, we assessed particle sinking velocities and their biogeochemical and physical drivers. We further characterized the general properties of exported particles under different phytoplankton communities and nutritional states. Average sinking velocities varied between size classes and ranged from 12.8 ± 0.7 m d−1 (particles 40–100 µm) to 19.4 ± 0.7 m d−1 (particles 100–250 µm) and 34.2 ± 1.5 m d−1 (particles 250–1000 µm) (± 95 % CI). Despite a distinct plankton succession from diatoms to dinoflagellates with concomitant 5-fold drop in opal ballasting, substantial changes in sinking velocity were not observed. This illustrates the complexity of counteracting factors driving the settling behaviour of marine particles. In contrast, we found higher sinking velocities with increasing particle size and roundness and decreasing porosity. Size had by far the strongest influence among these physical particle properties, despite a high amount of unexplained variability. Our study provides a detailed analysis of the drivers of particle sinking velocity in the Peruvian upwelling system, which allows modellers to optimize local particle flux parameterization. This will help to better project oxygen concentrations and carbon sequestration in a region that is subject to substantial climate-driven changes.

As one of Earth’s most productive marine ecosystems, the Peruvian Upwelling System transports large amounts of biogenic matter from the surface to the deep ocean. Whilst particle sinking velocity is a key factor controlling the biological pump, thereby affecting carbon sequestration and O2-depletion, it has not yet been measured in this system. During a 50-day mesocosm experiment in the surface waters off the coast of Peru, we measured particle sinking velocities and their biogeochemical and physical drivers. We further characterized the general properties of exported particles under different phytoplankton communities and nutritional states. Average sinking velocities varied between size classes and ranged from 12.8 ± 0.7 m d-1 (particles 40–100 µm), to 19.4 ± 0.7 m d-1 (particles 100–250 µm), and 34.2 ± 1.5 m d-1 (particles 250–1000 µm) (±95% CI). Surprisingly, no relationship between opal ballast and sinking velocity could be identified, despite the presence of diatoms, questioning the importance of opal ballast in freshly produced material sinking from the surface. In contrast, we found higher sinking velocities with increasing particle size, compactness and roundness. Size had by far the strongest influence among these physical particle properties. Our study provides a detailed analysis of the drivers of particle sinking velocity in the Peruvian Upwelling System, which allows modelers to optimize local particle flux parameterization. This will help to better project oxygen concentrations and carbon sequestration in a region that is subject to substantial climate-driven changes.

Gravitational sinking of photosynthetically fixed particulate organic carbon (POC) constitutes a key component of the biological carbon pump. The fraction of POC leaving the surface ocean depends on POC sinking velocity (SV) and remineralization rate (Cremin), both of which depend on plankton community structure. However, the key drivers in plankton communities controlling SV and Cremin are poorly constrained. In fall 2014, we conducted a 6 weeks mesocosm experiment in the subtropical NE Atlantic Ocean to study the influence of plankton community structure on SV and Cremin. Oligotrophic conditions prevailed for the first 3 weeks, until nutrient‐rich deep water injected into all mesocosms stimulated diatom blooms. SV declined steadily over the course of the experiment due to decreasing CaCO3 ballast and – according to an optical proxy proposed herein – due to increasing aggregate porosity mostly during an aggregation event after the diatom bloom. Furthermore, SV was positively correlated with the contribution of picophytoplankton to the total phytoplankton biomass. Cremin was highest during a Synechococcus bloom under oligotrophic conditions and in some mesocosms during the diatom bloom after the deep‐water addition while it was particularly low during harmful algal blooms. The temporal changes were considerably larger in Cremin (max. 15‐fold) than in SV (max. 3‐fold). Accordingly, estimated POC transfer efficiency to 1000 m was mainly dependent on how the plankton community structure affected Cremin. Our approach revealed key players and interactions in the plankton food web influencing POC export efficiency thereby improving our mechanistic understanding of the biological carbon pump. Key points Sinking velocity was higher during oligotrophy than during blooms which is linked to ballast, porosity, and phytoplankton size structure Remineralization was highly variable but tended to be higher during Synechococcus or diatom blooms and lower during harmful algal blooms

Planktonic Foraminifera and thecosome pteropods are major producers of calcite and aragonite in the ocean and play an important role for pelagic carbonate flux. The responses of planktonic foraminifers to ocean acidification (OA) are variable among the species tested and so far do not allow for reliable conclusion. Thecosome pteropods respond with reduced calcification and shell dissolution to OA and are considered at high risk especially at high latitudes. The present investigation was part of a large-scale in situ mesocosm experiment in the oligotrophic waters of the eastern subtropical North Atlantic. Over 62 days, we measured the abundance and vertical flux of pelagic foraminifers and thecosome pteropods as part of a natural plankton community over a range of OA scenarios. A bloom phase was initiated by the introduction of deep-water collected from approx. 650 m depth simulating a natural up-welling event. Foraminifers occurred throughout the entire experiment in both the water column and the sediment traps. Pteropods were present only in small numbers and disappeared after the first two weeks of the experiment. No significant CO2 related effects were observed for foraminifers, but cumulative sedimentary flux was reduced at the highest CO2 concentrations. This flux reduction was most likely accompanying an observed flux reduction of particulate organic matter (POM) so that less foraminifers were intercepted and transported downward.

Oceanic uptake of anthropogenic carbon dioxide (CO2) causes pronounced shifts in marine carbonate chemistry and a decrease in seawater pH. Increasing evidence indicates that these changes—summarized by the term ocean acidification (OA)—can significantly affect marine food webs and biogeochemical cycles. However, current scientific knowledge is largely based on laboratory experiments with single species and artificial boundary conditions, whereas studies of natural plankton communities are still relatively rare. Moreover, the few existing community-level studies were mostly conducted in rather eutrophic environments, while less attention has been paid to oligotrophic systems such as the subtropical ocean gyres. Here we report from a recent in situ mesocosm experiment off the coast of Gran Canaria in the eastern subtropical North Atlantic, where we investigated the influence of OA on the ecology and biogeochemistry of plankton communities in oligotrophic waters under close-to-natural conditions. This paper is the first in this Research Topic of Frontiers in Marine Biogeochemistry and provides (1) a detailed overview of the experimental design and important events during our mesocosm campaign, and (2) first insights into the ecological responses of plankton communities to simulated OA over the course of the 62-day experiment. One particular scientific objective of our mesocosm experiment was to investigate how OA impacts might differ between oligotrophic conditions and phases of high biological productivity, which regularly occur in response to upwelling of nutrient-rich deep water in the study region. Therefore, we specifically developed a deep water collection system that allowed us to obtain ~85 m3 of seawater from ~650 m depth. Thereby, we replaced ~20% of each mesocosm's volume with deep water and successfully simulated a deep water upwelling event that induced a pronounced plankton bloom. Our study revealed significant effects of OA on the entire food web, leadin

The ocean's potential to export carbon to depth partly depends on the fraction of primary production (PP) sinking out of the euphotic zone (i.e., the e-ratio). Measurements of PP and export flux are often performed simultaneously in the field, although there is a temporal delay between those parameters. Thus, resulting e-ratio estimates often incorrectly assume an instantaneous downward export of PP to export flux. Evaluating results from four mesocosm studies, we find that peaks in organic matter sedimentation lag chlorophyll a peaks by 2 to 15 days. We discuss the implications of these time lags (TLs) for current e-ratio estimates and evaluate potential controls of TL. Our analysis reveals a strong correlation between TL and the duration of chlorophyll a buildup, indicating a dependency of TL on plankton food web dynamics. This study is one step further toward time-corrected e-ratio estimates

Progressive ocean acidification due to anthropogenic CO2 emissions will alter marine ecosytem processes. Calcifying organisms might be particularly vulnerable to these alterations in the speciation of the marine carbonate system. While previous research efforts have mainly focused on external dissolution of shells in seawater under saturated with respect to calcium carbonate, the internal shell interface might be more vulnerable to acidification. In the case of the blue mussel Mytilus edulis, high body fluid pCO2 causes low pH and low carbonate concentrations in the extrapallial fluid, which is in direct contact with the inner shell surface. In order to test whether elevated seawater pCO2 impacts calcification and inner shell surface integrity we exposed Baltic M. edulis to four different seawater pCO2 (39, 142, 240, 405 Pa) and two food algae (310–350 cells mL−1 vs. 1600–2000 cells mL−1) concentrations for a period of seven weeks during winter (5°C). We found that low food algae concentrations and high pCO2 values each significantly decreased shell length growth. Internal shell surface corrosion of nacreous ( = aragonite) layers was documented via stereomicroscopy and SEM at the two highest pCO2 treatments in the high food group, while it was found in all treatments in the low food group. Both factors, food and pCO2, significantly influenced the magnitude of inner shell surface dissolution. Our findings illustrate for the first time that integrity of inner shell surfaces is tightly coupled to the animals' energy budget under conditions of CO2 stress. It is likely that under food limited conditions, energy is allocated to more vital processes (e.g. somatic mass maintenance) instead of shell conservation. It is evident from our results that mussels exert significant biological control over the structural integrity of their inner shell surfaces.

Pencak silat is a form of martial arts indigenous to the Malay derived ethnic groups that populate mainland and island Southeast Asia. Far from being merely a form of selfdefense, pencak silat is a pedagogic method that seeks to embody particular cultural and social ideals within the body of the practitioner. The history, culture and practice ofpencak in West Java is the subject of this study. As a form of traditional education, a performance art, a component of ritual and community celebrations, a practical form of self-defense, a path to spiritual enlightenment, and more recently as a national and international sport, pencak silat is in many respects unique. It is both an integrative and diverse cultural practice that articulates a holistic perspective on the world centering upon the importance of the body as a psychosomatic whole. Changing socio-cultural conditions in Indonesia have produced new forms of pencak silat. Increasing government intervention in pencak silat throughout the New Order period has led to the development of nationalized versions that seek to inculcate state-approved values within the body of the practitioner. Pencak silat groups have also been mobilized for the purpose of pursuing political aims. Some practitioners have responded by looking inwards, outlining a path to self-realization framed by the powers, flows and desires found within the body itself. Others have developed styles that reflect the demands made upon them by their immediate environment. Viewed historically these changes in the practice of pencak silat provides insights into the impact of broader processes of social and cultural change at the level of individual bodies and the institutions through which they are constructed; a politics of the body, its potentialities, limits and 'legitimate' use.

This thesis explores the question of why health development, indicated by a reduction in maternal and infant mortality rates, has been relatively slow in the district of East Lombok, in the province of Nusa Tenggara Barat, Indonesia. It describes the political, economic, social and cultural character of Sasak village life, and the historical and wider politico-economic context in which it is embedded. The thesis fulfils the requirements of the emerging field of critical medical anthropology, paying attention not only to culture, but also to political economy; not only at the local (or micro) level, but also at the macro and intermediary levels. The objective of part one is to offer a broad analysis which demonstrates the local, regional and national political and economic constraints upon reducing maternal and infant mortality rates in rural East Lombok. Part two critically examines international and national health development discourses, which, it is argued, depoliticise the issue of health inequalities, and represent local people as sole cause of their poor health status. It also discusses the political effects of the process of medicalisation. This thesis is based on ethnographic research, the focus of which is the interface between rural Sasak women and local government health staff, who deliver medical interventions through the national family planning and primary health care programmes. At the local level economic, political, social and cultural factors determine the everyday decisions women make about where and when to seek preventative and curative treatment for themselves and their infants. It is at this local level that the disjuncture between Sasak theories of illness causation and healing practices, and those of biomedicine which inform the policies and interventions of government health development planners, are revealed. Similarly, it is at this level that the disjuncture between the planned and the actual quality and quantity of health interventions

This thesis uses ethnographic research and interrogation of a number of discourses and tropes to examine the street-side performances of a group of young male kampung-dwellers in a part of urban Yogyakarta I call Kusuman. These young men, who refer to their group as the cah-cah (lads) are located between the socially defined roles of uncircumcised children and married heads of households, and have an ambiguous status in their communities. Among other lads in the same liminal phase they act out a series of personas in an attempt to construct meaningful identities. Their performances are re-iterations or re-interpretations of tropes to which they are exposed. The Javaneseness of wayang, elaborate politeness codes and stratified language, the Indonesianness of Pancasila, mutual help and military parades, and a Javanised mystical version of Islam form a background to their knowledge of self and society. These idioms also offer scope for playing out resistant readings, through reversal and caricature, as do the mystical martial-arts comics they devour and the trickster heroes of their folk mythology. Tourism is a major cultural and economic influence on Kusuman, and their repertoire of tropes is expanded by the performances of the "wild guides", English-speaking opportunists who seek sex, money and to "change their thinking with a western woman" among the many tourists passing through Kusuman.

This is an original dissertation on Mazar (Sufi shrine) culture in Bangladesh, emphasising its socio-religious dimensions. Mazar culture is a dominating force in Bangladeshi culture. It is comprised of history, myths, mystical powers, social roles and religious significance. Currently, Mazar culture is an issue of religious debate between the Sufi (Muslim saints) and non-Sufi traditions in Bangladesh. Controversy centres on the religious validity of devotional intensity with regard to veneration of Sufis and their Mazars, the two key factors of Mazar culture. In this regard, the unlettered Baul Fakirs (mystic singers belonging to Sufi tradition) have received prominence for violating the Shariat and their oral discourses on socio-religious issues. This thesis notes that the Mazar culture of Bangladesh inherits the cultural traits of immigrant Sufis who converted many indigenous non-Muslims to Islam in the medieval period. To establish a new tradition, the Sufis illustrated Quranic declarations about the super human power of the Auliya (sages), alive or departed. History reveals that Sanatan (indigenous) esotericism had semblances with Islamic mysticism. The Sufis took advantage of this by mingling the two cultures and projecting miraculous power, which made them the object of veneration similar to the earlier prevalent Guru Bhakti (veneration). It is also observed that the spirit of Sufi mysticism is still manifest widely in Bengali culture. Diverse Sufi teachings gave birth to the traditions of Shariati (eso-exoteric) Pirs, or Ulama (learned), and the Marifati (esoteric) Pirs or mystic Baul Fakirs. These two groups have different views of Mazar veneration. They have produced an unending polemical discourse between them in regard with the illustrative approaches to Mazar veneration. Moreover, "The Tablig Jamaat", a preaching society and reformist group hostile to some aspects of Islamic mysticism, has aggravated the situation. The Jamaat is mainly concerned with the