Antarctic marine mammals and ocean acoustics

Marine mammals rely on sound and hearing as their primary means of communication and sensing their world. Concerns that anthropogenic sound in the ocean could infer their sensing, cause stress or even damage their hearing physically rose a controversial discussion and triggered a worldwide boost in marine bioacoustic research. Innovative acoustic technologies and field methods are required to provide a basis for carefully designed and technically challenging research projects on free-ranging marine mammals, especially under the harsh environmental conditions of polar regions. The Ocean Acoustics group within the Marine Observing Systems section endeavors multidisciplinary research of environmental scientists, geophysicists, oceanographers, physicists, physiologists, and biologists to investigate the need and scope of mitigation measures for the effects of man-generated sound in the ocean, develop acoustic census techniques, explore marine mammal responses to various anthropogenic sounds, and study the vocal behaviour and hearing physiology of Antarctic marine mammals

Nosocomial methicillin-resistant staphylococcus aureus (MRSA) pneumonia: linezolid or vancomycin? - Comparison of pharmacology and clinical efficacy

The incidence of nosocomial pneumonia involving methicillin-resistant Staphylococcus aureus strains (MRSA) is on the rise worldwide. For years, vancomycin has been used as the drug of choice in the treatment of MRSA infections and was recommended as such by clinical guidelines. There is growing evidence that vancomycin, despite low resistance rates is a suboptimal therapeutic option in critically ill patients, particularly in patients with pneumonia. Disadvantages of vancomycin are i) slow bactericide action, ii) poor penetration into pulmonary tissue, iii) the globally slowly increasing vancomycin MICs ("creep") that result in increased clinical failure despite being susceptible according to defined break points and iv) nephrotoxicity. In contrast to other novel antibiotics with MRSA activity, Linezolid is currently approved for the treatment of nosocomial pneumonia in the USA and Europe. Several studies have compared vancomycin with linezolid for nosocomial pneumonia with conflicting results. This review compares both substances regarding pharmacodynamics, resistance, safety and clinical efficacy and discusses preliminary data of the ZEPHyR study. This study compared linezolid versus vancomycin in patients with proven MRSA pneumonia and was the largest trial ever conducted in this population

A Useful Radiologic Method for Preoperative Joint-line Determination in Revision Total Knee Arthroplasty

Intraoperative joint-line determination during revision TKA is difficult and no method exists to plan the position preoperatively. Two questions need to be answered: to which extent does the joint line differ from its anatomic position after revision TKA if it has only been determined intraoperatively, and can the joint line be calculated preoperatively based on the transepicondylar width. Of 22 consecutive patients with complete preoperative (before and after primary TKA) and postoperative (after revision TKA) radiograph documentation, the joint-line position was measured on plane radiographs using the medial epicondyle as a reference. On another set of 45 consecutive patients with no knee disorders other than meniscal lesions, the transepicondylar axis width (TEAW) and the perpendicular distance from the medial and lateral epicondyles to the joint line were measured twice by two independent observers on plane AP radiographs of the knee. Significant joint-line alterations were observed after primary and revision TKA, implicating that a method for preoperative planning is needed. Because a linear correlation between the TEAW and the perpendicular distance from the epicondyles to the joint-line tangent was found, the ratio is useful to calculate the true joint-line position from the TEAW before revision TKA. Level of Evidence: Level III, therapeutic study. See Guidelines for Authors for a complete description of levels of evidenc

Static species distribution models in the marine realm: The case of baleen whales in the Southern Ocean

Aim Information on the spatio-temporal distribution of marine species is essential for developing proactive management strategies. However, sufficient information is seldom available at large spatial scales, particularly in polar areas. The Southern Ocean (SO) represents a critical habitat for various species, particularly migratory baleen whales. Still, the SO’s remoteness and sea ice coverage disallow obtaining sufficient information on baleen whale distribution and niche preference. Here, we used presence-only species distribution models to predict the circumantarctic habitat suitability of baleen whales and identify important predictors affecting their distribution. Location The Southern Ocean (SO). Methods We used Maxent to model habitat suitability for Antarctic minke, Antarctic blue, fin and humpback whales. Our models employ extensive circumantarctic data and carefully prepared predictors describing the SO’s environment and two spatial sampling bias correction options. Species-specific spatial-block cross-validation was used to optimize model complexity and for spatially independent model evaluation. Results Model performance was high on cross-validation, with generally little predicted uncertainty. The most important predictors were derived from sea ice, particularly seasonal mean and variability of sea ice concentration and distance to the sea ice edge. Main conclusions Our models support the usefulness of presence-only models as a cost-effective tool in the marine realm, particularly for studying the migratory whales’ distribution. However, we found discrepancies between our results and (within) results of similar studies, mainly due to using different species data quality and quantity, different study area extent and methodological reasons. We further highlight the limitations of implementing static distribution models in the highly dynamic marine realm. Dynamic models, which relate species information to environmental conditions contemporaneous to species occurrences, can predict near-real-time habitat suitability, necessary for dynamic management. Nevertheless, obtaining sufficient species and environmental predictors at high spatio-temporal resolution, necessary for dynamic models, can be challenging from polar regions

Vocal behaviour of bowhead whales (Balaena mysticetus) in eastern Fram Strait

Bowhead whales (Balaena mysticetus) of the East Greenland-Svalbard-Barents Sea (Spitsbergen) population have been depleted close to the point of extinction by commercial whaling and are still considered as endangered. Due to their low abundance and the remoteness of their habitat, baseline knowledge on spatio-temporal distribution patterns and behavioural aspects are scarce, yet crucial for the conservation of this population. Long-term passive acoustic recordings were collected at different locations in eastern Fram Strait (78-79°N, 0-7°E) as part of the Ocean Observing System FRAM (Frontiers in Arctic Marine Monitoring). Data recorded in 2012 and 2016/2017 were analysed for the acoustic occurrence of bowhead whales at an hourly resolution using an automated detector. Bowhead whales were acoustically present from autumn throughout the winter months (October-February) and occasionally in spring (March-June), supporting hypotheses that Fram Strait is an important overwintering area. Acoustic presence peaked between mid-November and mid-December when bowhead whales were recorded almost daily, often hourly for several days in a row. The observed peak in acoustic presence coincided with the presumed mating period of bowhead whales, starting in late winter, indicating that Fram Strait may also serve as a mating area. Detailed analyses of recordings of a single year and location revealed eight distinct bowhead whale song types comprising simple songs and call sequences. No bowhead whales were recorded in summer (July-September), indicating that they either were vocally inactive or had migrated to summering areas. Compared to previous studies in western Fram Strait, bowhead whale detections in our recordings were less frequent and less complex. The observed regional differences in bowhead whale acoustic behaviour across Fram Strait suggest that our mooring locations in eastern Fram Strait may represent the eastern distribution boundary of the bowhead whale overwintering area

Acoustic presence and vocal repertoire of bowhead whales (Balaena mysticetus) in eastern and central Fram Strait

Bowhead whales (Balaena mysticetus) of the East Greenland-Svalbard-Barents Sea (Spitsbergen) population are still considered endangered, but knowledge on spatio-temporal distribution patterns and behavioral aspects remains scarce, yet crucial for this population’s conservation. Long-term passive acoustic recordings were collected at five locations in central and eastern Fram Strait (78-79°N, 0-7°E) as part of the Ocean Observing System FRAM (Frontiers in Arctic Marine Monitoring). Data recorded in 2012 and 2016/2017 were analyzed for the acoustic occurrence of bowhead whales at hourly resolution using a combination of automated and manual analyses. Bowhead whales were acoustically present from autumn throughout the winter months (October-February) and occasionally in spring (March-June), supporting hypotheses that Fram Strait is an important overwintering area. Acoustic presence peaked between mid-November and mid-December with bowhead whale calls recorded almost daily, often hourly for several consecutive days. The observed peak in acoustic presence coincided with the presumed mating period of bowhead whales, starting in late winter, indicating that Fram Strait may also serve as a mating area. Detailed analyses of recordings of a single year and location revealed eight distinct bowhead whale song types, comprising simple songs and call sequences. No bowhead whales were recorded in summer (July-September), indicating that they had migrated to summering areas or resided outside the detection range. Compared to previous studies in western Fram Strait, bowhead whale detections in our recordings were less frequent and recorded songs were less complex. The observed regional differences in bowhead whale acoustic behavior across Fram Strait suggest that eastern Fram Strait may represent a less favorable part of the bowhead whale overwintering area.</jats:p

Umwelterheblichkeitsstudie (UES) für den Einsatz von hydroakustischen Messgeräten im Rahmen von marinen Forschungsvorhaben im Bereich des Antarktisvertrages

1. Die Struktur der UES orientiert sich an dem Merkblatt "Anforderungen an eine Umwelterheblichkeitsstudie (UES)", das vom UBA in 2015 herausgegeben wurde. 2. In Kapitel 2 wird das Untersuchungsgebiet (aufgeteilt in 3 Untergebiete) beschrieben, in denen die in dieser UES behandelten hydroakustischen Geräte eingesetzt werden. Kapitel 2 enthält zudem eine Beschreibung der in dieser UES zu betrachtenden marinen Säugetiere (14 Wal- und 6 Robbenarten), die in der Antarktis heimisch sind und die in einzelnen Bereichen des Untersuchungsgebietes angetroffen werden können. Die aus der Literatur entnommen Beschreibung der Walarten konnte leider aus Zeitgründen noch nicht ins Deutsche übersetzt werden. 3. Kapitel 3 beschreibt die in dieser UES behandelten hydroakustischen Geräte (Fächerlot Hydrosweep DS3, Sedimentecholot Parasound P70, Echolot EK60/80 im Einzelkanal- und Mehrkanal-Modus, Ortungssysteme Posidonia und GAPS) und wie diese im Bereich des Antarktisvertrages im Rahmen wissenschaftlicher Forschungen eingesetzt werden. Fact Sheets mit den technischen Daten dieser Geräte sind in separaten Annexen der Studie beigefügt. 4. Kapitel 4 stellt dar, dass es für den Einsatz der o.g. hydroakustischen Geräte derzeit keine Alternativen gibt. 5. In Kapitel 5 werden die potentiellen Auswirkungen auf die in Kap. 2 beschriebenen marinen Säugetierarten betrachtet, die durch den Einsatz der o.g. hydroakustischen Geräte entstehen könnten. Zentraler Aspekt hierbei ist die neue Modellierung der von den Geräten erzeugten räumlichen Schallfelder. Diese sind Grundlage für die Abschätzungen der Risiken, dass es durch die Schallemissionen zu Auswirkungen auf marine Säugetiere kommen könnte. Diese Modellierungen und Risikobetrachtungen sind separat für jedes Gerät in Annex 10 - Annex 15 dargestellt. 6. Kapitel 6 gibt die bislang angewandten Genehmigungsauflagen und die zusätzlichen Maßnahmen wider, welche beim Einsatz der hydroakustischen Geräte zur Minimierung des Risikos von Auswirkungen durchgeführt werden. 7. Kapitel 7 geht auf die z.T. erheblichen Wissenslücken und unvermeidlichen Unsicherheiten ein, welche bei der Betrachtung und Bewertung der potentiellen Auswirkungen durch den Einsatz der o.g. hydroakustischen Geräte berücksichtigt werden müssen. Diese Lücken und Unsicherheiten betreffen besonders die in dieser UES betrachteten Säugetierarten (für die es kaum wissenschaftliche Untersuchungen gibt) als auch die fehlende und/oder unterschiedliche Auslegung von Begriffsdefinitionen für die objektive Bewertung der potentiellen Auswirkungen auf marine Säuger. 8. Kapitel 8 fasst die wichtigsten Ergebnisse und Schlussfolgerungen dieser UES zusammen

The marine soundscape off Elephant Island: A Southern Ocean coastal habitat

Here we present a comprehensive description of the acoustic environment approximately 31 km west-northwest of Minstrel Point, Elephant Island, Antarctica at 210 m water depth based on three years (Jan 2013 – Feb 2016) of subsampled (5 min per hour) passive acoustic recordings. Long-term spectrograms reveal a notable recurrence of acoustic environments between years. Fin and Antarctic blue whale calls dominate the low (< 100 Hz) part of the biophonic spectrum energetically from end of January to late July/early August. November through early January are dominated by leopard seal vocalizations at around 300 Hz. Concurrently, the geophonic spectrum exhibits strong fluctuations between days, both due to storm and tidal influences, causing flow and shackle noise from the instrumentation itself. Manual analysis of every second day of the subsampled data by visual and aural screening (employing short term spectrograms) was used to examine the data in greater detail for additional acoustic contributions and to assign the various acoustic signatures to their sources. Six cetacean and two pinniped species were identified based on their acoustic signatures and analysed for seasonal and diel patterns in occurrence. Anthrophonic signatures were attributed to air guns on 3 % of the analysed days. Vessel noise was noted between 10 and 12% of days on annual averages, occurring mainly in austral summer and fall with sporadic events throughout the remainder of the year

Fin whale (Balaenoptera physalus) acoustic presence off Elephant Island, Antarctica

Recent visual observations suggest that the region around Elephant Island serves as an important feeding area for fin whales. Passive acoustic recordings collected northwest of Elephant Island (61°0.88’S, 55°58.53’W) from January 2013 to February 2016 were analysed manually for seasonal and diel patterns of fin whale 20 Hz calls. Overall, calls were detected year-round, although in some years calls were not present during all months. For all years, fin whale calls were consistently present from February to July for more than 90% of days per month. From August to January, percentage of days with calls varied between years, with presence exceeding 75% of days per month throughout 2014, whereas in 2015 calls were absent in October and November. In 2013, fin whale calling dropped in August and increased again towards November (present 80% of days per month). Diel patterns in call activity were analysed for a 10-month subset of the data from 2013. Fluctuations in call rates did not follow a diel pattern nor correspond to local insolation. During peak calling period, maximum calls amounted approximately to 80 per 10-minute file. Fluctuations in call presence outside the peak calling period may be explained by variation in local ice conditions as drift may temporally force the animals away to areas with reduced ice concentrations. Furthermore, delays in the timing of migration between age groups, sexes and/or reproductive classes may also affect temporal patterns in the clustering of calls. The observed peaks in fin whale call activity correspond to the periods during which fin whale super groups have been repeatedly observed visually in this region. Our year-round acoustic analysis indicates that the Elephant Island region is likely to play an important role for fin whales throughout the remainder of the year