Direct visualization of mucus production by the cold-water coral <i>Lophelia pertusa</i> with digital holographic microscopy

<i>Lophelia pertusa</i> is the dominant reef-building organism of cold-water coral reefs, and is known to produce significant amounts of mucus, which could involve an important metabolic cost. Mucus is involved in particle removal and feeding processes, yet the triggers and dynamics of mucus production are currently still poorly described because the existing tools to study these processes are not appropriate. Using a novel microscopic technique—digital holographic microscopy (DHM)–we studied the mucus release of <i>L</i>. <i>pertusa</i> under various experimental conditions. DHM technology permits µm-scale observations and allows the visualization of transparent mucoid substances in real time without staining. Fragments of <i>L</i>. <i>pertusa</i> were first maintained in flow-through chambers without stressors and imaged with DHM, then exposed to various stressors (suspended particles, particulate food and air exposure) and re-imaged. Under non-stressed conditions no release of mucus was observed, whilst mucus strings and sheaths were produced in response to suspended particles (activated charcoal and drill cuttings sediment) i.e. in a stressed condition. Mucus strings and so-called ‘string balls’ were also observed in response to exposure to particulate food (brine shrimp <i>Artemia salina</i>). Upon air-exposure, mucus production was clearly visible once the fragments were returned to the flow chamber. Distinct optical properties such as optical path length difference (OPD) were measured with DHM in response to the various stimuli suggesting that different mucus types are produced by <i>L</i>. <i>pertusa</i>. Mucus produced to reject particles is similar in refractive index to the surrounding seawater, suggesting that the energy content of this mucus is low. In contrast, mucus produced in response to either food particle addition or air exposure had a higher refractive index, suggesting a higher metabolic investment in the production of these mucoid substances. This paper shows for the first time the potential of DHM technology for the detection, characterization and quantification of mucus production through OPD measurements in <i>L</i>. <i>pertusa</i>

Disrupted histories, recovered pasts: a cross-disciplinary analysis and cross-case synthesis of oral histories and history in post-conflict and postcolonial contexts

This working paper outlines the conceptual framework and case studies comprising the research project Disrupted Histories, Recovered Pasts. Our project proposes a cross-disciplinary analysis and cross-case synthesis of experience and memory in post-conflict and postcolonial contexts. In the postconflict and colonial contexts of our cases, we see ‘disruption’ as present in three senses: as the productive ways in which multiple experiences retrieved through oral histories may refract and revise historical analysis; as the happening histories of objectively disruptive events break the flow of individual and collective experience; and as a strategy for cross-disciplinary research to disrupt and democratise conventional understanding by drawing attention to occluded experiences. We also articulate ‘recovery’ as polysemic: invoking retrieval of past experiences and the possibility for enhanced well-being through voicing memories that may have been suppressed, as well as attending to mismatches with public discourses about displaced groups and individual experience. Following an introduction to our conceptual approach, we summarise our proposed and on-going case-research. We are conducting oral history and archival research in multiple contexts, conducted from disciplinary bases in anthropology and history. Our aim is to interrogate relationships between oral histories and amateur histories with more formal written archives and historiography in a series of disrupted settings: evictions in colonial and apartheid west Namibia (Sullivan); memories and historical interpretations of the Egyptian Jewish diaspora (Baussant); the evacuation of children in Second World War France (Dodd); recent maritime exodus of migrants from Africa (Otele); and rupture from a hegemonic imperial-nostalgic narrative in Portugal (Dos Santos). Our case research will be complemented by systematic cross-case engagement, synthesis, theorisation and communication of case-study research, to be shared in the first instance through a future working paper

Disrupted histories, recovered pasts: an introduction

This introductory paper outlines the conceptual framework and case studies comprising the research project 'Disrupted Histories, Recovered Pasts'. Our project proposes a cross-disciplinary analysis and cross-case synthesis of experience and memory in post-conflict and postcolonial contexts. In the post- conflict and colonial contexts of our cases, we see “disruption” as present in three senses: as the productive ways in which multiple experiences retrieved through oral histories may refract and revise historical analysis; as the happening histories of objectively disruptive events break the flow of individual and collective experience; and as a strategy for cross-disciplinary research to disrupt and democratise conventional understanding by drawing attention to occluded experiences. We also articulate “recovery” as polysemic: invoking retrieval of past experiences and the possibility for enhanced well-being through voicing memories that may have been suppressed, as well as attending to mismatches with public discourses about displaced groups and individual experience. Following an introduction to our conceptual approach, we summarise our case-research. We have conducted oral history and archival research in multiple contexts, from disciplinary bases in anthropology and history. Our aim has been to interrogate relationships between oral histories and amateur histories with more formal written archives and historiography in a series of disrupted settings: evictions in colonial and apartheid west Namibia (SULLIVAN); memories and historical interpretations of the Egyptian Jewish diaspora (BAUSSANT); the evacuation of children in Second World War France (DODD); recent maritime exodus of migrants from Africa (OTELE); and rupture from a hegemonic imperial-nostalgic narrative in Portugal (DOS SANTOS). Our case research is complemented in the concluding paper of this Special Issue by systematic cross-case engagement, synthesis and theorisation of our case-study research

Cross-case synthesis: doing together

The project ‘Disrupted Histories, Recovered Pasts’ forming the focus of this Special Issue has researched biographical experiences that have undergone a rupture as a result of brutal political, social and/or economic changes, linked especially with war, colonization/decolonization, migration and exile. These personal biographical experiences have tended to find themselves on the margins of national and/or academic historical narratives. In this final paper of our Special Issue we share the open-ended process of co-production, cross-case learning, and synthesis that accompanied case research, focusing especially on our systematic cross-case engagement, which involved sharing and theorising content and experiences across our case-studies, and the commonalities and differences we identified across our case-studies through this process. We outline the steps we took in this process to sharing what we know, find ‘points of articulation’ across our case-studies and to identify themes emerging across our research

lmpacts of drilling mud discharges on water column organism and filter feeding bivalves

The two main objectives of our project was to study possible effects of drilling mud discharges on water column organism (plankton and fish), and filter feeding bivalves, and to analyse metals in fish and bivalves exposed to suspended particles of drilling mud to find out if metals from the mud was taken up by the organisms. The results from the different parts of the project have been reported in 8 manuscripts/reports. The ultimate aim is to publish as many of these manuscripts as possible. Hence this report is a collection of early versions of future publications