Mark F. Baumgartner

Atmospheric forcing in the Arabian Sea during 1994–1995: observations and comparisons with climatology and models

Accurate, year-long time series of winds, incoming shortwave and longwave radiation, air and sea temperatures, relative humidity, barometric pressure, and precipitation were collected from a surface mooring deployed off the coast of Oman along the climatological axis of the Findlater Jet from October 1994 to October 1995. Wind stress, heat flux, and freshwater flux were computed using bulk formulae. The Northeast Monsoon was characterized by steady but moderate winds, clear skies, relatively dry air, and two months, December and January, in which the ocean, on average, lost 45 W m-2 to the atmosphere. The Southwest Monsoon had strong winds, cloudy skies, and moist air. Because of reduced latent and longwave heat loss, it was accompanied by sustained oceanic heat gain, with the strongest monthly mean warming, 147 W m-2, in August. Large differences are found between the observations and older climatologies. Recent climatologies agree better with the observations. The means of the Southampton Oceanography Center climatology for 1980–1995 are close to the buoy monthly means. Monthly means from that climatology show that 1994–1995 was in general a typical year, with surface meteorology and air–sea fluxes within one standard deviation of the long term means. Concurrent data from the NCEP, ECMWF, and FNMOC show that the models provide realistic surface winds. FNMOC winds show that the timing and character of the onset of the Southwest Monsoon in 1995 differed from 1994 and 1996 when variability within one month is resolved. The models fail to replicate other observed surface meteorology and to produce realistic heat fluxes. Annual and monsoonal mean net heat fluxes from the models differed from those of the buoy by 50 to 80 W m-2. Because of these differences, some care is warranted in selecting and using air-sea flux fields in studies of the Arabian Sea.

North Atlantic right whales, Eubalaena glacialis, exposed to paralytic shellfish poisoning (PSP) toxins via a zooplankton vector, Calanus finmarchicus

Abstract The seriously endangered north Atlantic right whale ( Eubalaena glacialis ) is regularly exposed to the neurotoxins responsible for paralytic shellfish poisoning (PSP) through feeding on contaminated zooplankton acting as a vector of these dinoflagellate toxins. This chronic exposure occurs during several months each summer while the whales are present on their late summer feeding ground in Grand Manan Basin in the lower Bay of Fundy. Based on estimated ingestion rates, we suggest that these toxins could affect respiratory capabilities, feeding behavior, and ultimately the reproductive condition of the whale population.

Radiative Heating Errors in Naturally Ventilated Air Temperature Measurements Made from Buoys

Abstract Solar radiative heating errors in buoy-mounted, naturally ventilated air temperature sensors are examined. Data from sensors with multiplate radiation shields and collocated, fan-aspirated air temperature sensors from three buoy deployments during TOGA COARE (Tropical Ocean Global Atmosphere Coupled Ocean–Atmosphere Response Experiment) and the Arabian Sea Mixed Layer Dynamics Experiment are used to describe the errors in the naturally ventilated measurements. The naturally ventilated sensors have mean daytime errors of 0.27°C and maximum instantaneous errors of 3.4°C. The errors are at times larger than the difference between the air and sea surface temperatures. These errors lead to mean daytime biases in sensible and latent heat fluxes of 1–4 W m−2 and instantaneous errors up to 22 W m−2. The heating errors increase with increasing shortwave radiation and diminish with increasing wind speed. The radiative heating is also found to be a function of sun elevation with maximum heating errors occur...

North Atlantic blue and fin whales suspend their spring migration to forage in middle latitudes: building up energy reserves for the journey?

The need to balance energy reserves during migration is a critical factor for most long-distance migrants and an important determinant of migratory strategies in birds, insects and land mammals. Large baleen whales migrate annually between foraging and breeding sites, crossing vast ocean areas where food is seldom abundant. How whales respond to the demands and constraints of such long migrations remains unknown. We applied a behaviour discriminating hierarchical state-space model to the satellite tracking data of 12 fin whales and 3 blue whales tagged off the Azores, to investigate their movements, behaviour (transiting and area-restricted search, ARS) and daily activity cycles during the spring migration. Fin and blue whales remained at middle latitudes for prolonged periods, spending most of their time there in ARS behaviour. While near the Azores, fin whale ARS behaviour occurred within a restricted area, with a high degree of overlap among whales. There were noticeable behavioural differences along the migratory pathway of fin whales tracked to higher latitudes: ARS occurred only in the Azores and north of 56°N, whereas in between these areas whales travelled at higher overall speeds while maintaining a nearly direct trajectory. This suggests fin whales may alternate periods of active migration with periods of extended use of specific habitats along the migratory route. ARS behaviour in blue whales occurred over a much wider area as whales slowly progressed northwards. The tracks of these whales terminated still at middle latitudes, before any behavioural switch was detected. Fin whales exhibited behavioural-specific diel rhythms in swimming speed but these varied significantly between geographic areas, possibly due to differences in the day-night cycle across areas. Finally, we show a link between fin whales seen in the Azores and those summering in eastern Greenland-western Iceland along a migratory corridor located in central Atlantic waters.

Heat shock protein expression during stress and diapause in the marine copepod Calanus finmarchicus

Calanoid copepods, such as Calanus finmarchicus, are a key component of marine food webs. C. finmarchicus undergo a facultative diapause during juvenile development, which profoundly affects their seasonal distribution and availability to their predators. The current ignorance of how copepod diapause is regulated limits understanding of copepod population dynamics, distribution, and ecosystem interactions. Heat shock proteins (Hsps) are a superfamily of molecular chaperones characteristically upregulated in response to stress conditions and frequently associated with diapause in other taxa. In this study, 8 heat shock proteins were identified in C. finmarchicus C5 copepodids (Hsp21, Hsp22, p26, Hsp90, and 4 forms of Hsp70), and expression of these transcripts was characterized in response to handling stress and in association with diapause. Hsp21, Hsp22, and Hsp70A (cytosolic subfamily) were induced by handling stress. Expression of Hsp70A was also elevated in shallow active copepodids relative to deep diapausing copepodids, which may reflect induction of this gene by varied stressors in active animals. In contrast, expression of Hsp22 was elevated in deep diapausing animals; Hsp22 may play a role both in short-term stress responses and in protecting proteins from degradation during diapause. Expression of most of the Hsps examined did not vary in response to diapause, perhaps because the diapause of C. finmarchicus is not associated with the extreme environmental conditions (e.g., freezing and desiccation) experienced by many other taxa, such as overwintering insects or Artemia cysts.

A generalized baleen whale call detection and classification system

Passive acoustic monitoring allows the assessment of marine mammal occurrence and distribution at greater temporal and spatial scales than is now possible with traditional visual surveys. However, the large volume of acoustic data and the lengthy and laborious task of manually analyzing these data have hindered broad application of this technique. To overcome these limitations, a generalized automated detection and classification system (DCS) was developed to efficiently and accurately identify low-frequency baleen whale calls. The DCS (1) accounts for persistent narrowband and transient broadband noise, (2) characterizes temporal variation of dominant call frequencies via pitch-tracking, and (3) classifies calls based on attributes of the resulting pitch tracks using quadratic discriminant function analysis (QDFA). Automated detections of sei whale (Balaenoptera borealis) downsweep calls and North Atlantic right whale (Eubalaena glacialis) upcalls were evaluated using recordings collected in the southwestern Gulf of Maine during the spring seasons of 2006 and 2007. The accuracy of the DCS was similar to that of a human analyst: variability in differences between the DCS and an analyst was similar to that between independent analysts, and temporal variability in call rates was similar among the DCS and several analysts.

Low frequency vocalizations attributed to sei whales (Balaenoptera borealis)

Low frequency (<100 Hz) downsweep vocalizations were repeatedly recorded from ocean gliders east of Cape Cod, MA in May 2005. To identify the species responsible for this call, arrays of acoustic recorders were deployed in this same area during 2006 and 2007. 70 h of collocated visual observations at the center of each array were used to compare the localized occurrence of this call to the occurrence of three baleen whale species: right, humpback, and sei whales. The low frequency call was significantly associated only with the occurrence of sei whales. On average, the call swept from 82 to 34 Hz over 1.4 s and was most often produced as a single call, although pairs and (more rarely) triplets were occasionally detected. Individual calls comprising the pairs were localized to within tens of meters of one another and were more similar to one another than to contemporaneous calls by other whales, suggesting that paired calls may be produced by the same animal. A synthetic kernel was developed to facilitate automatic detection of this call using spectrogram-correlation methods. The optimal kernel missed 14% of calls, and of all the calls that were automatically detected, 15% were false positives.

Real-time reporting of baleen whale passive acoustic detections from ocean gliders

In the past decade, much progress has been made in real-time passive acoustic monitoring of marine mammal occurrence and distribution from autonomous platforms (e.g., gliders, floats, buoys), but current systems focus primarily on a single call type produced by a single species, often from a single location. A hardware and software system was developed to detect, classify, and report 14 call types produced by 4 species of baleen whales in real time from ocean gliders. During a 3-week deployment in the central Gulf of Maine in late November and early December 2012, two gliders reported over 25,000 acoustic detections attributed to fin, humpback, sei, and right whales. The overall false detection rate for individual calls was 14%, and for right, humpback, and fin whales, false predictions of occurrence during 15-min reporting periods were 5% or less. Transmitted pitch tracks--compact representations of sounds--allowed unambiguous identification of both humpback and fin whale song. Of the ten cases when whales were sighted during aerial or shipboard surveys and a glider was within 20 km of the sighting location, nine were accompanied by real-time acoustic detections of the same species by the glider within ±12 h of the sighting time.

Coupling of internal waves on the main thermocline to the diurnal surface layer and sea surface temperature during the Tropical Ocean-Global Atmosphere Coupled Ocean-Atmosphere Response Experiment

Patterns in sea surface temperature (SST) on 5-km scales were observed from low-flying research aircraft on a light wind day during the Tropical Ocean-Global Atmosphere Coupled Ocean-Atmosphere Response Experiment. An inverse trend was observed between the SST and the sea surface mean square slope (mss). However, low correlation coefficients indicate that the dominant process causing the spatial variation of SST under these light wind conditions is neither well controlled by the wind speed nor well monitored by the mss. The SST spatial pattern persisted for at least 1 hour and propagated toward the NE at about 1 m s−1, a factor of 1.6 faster than the speed of the surface current. Coupling between internal gravity waves propagating on the seasonal thermocline and the diurnal surface layer is examined as a possible explanation for the observed SST variability in space and time.

Assessing performance of Bayesian state-space models fit to Argos Satellite telemetry locations processed with Kalman Filtering

Argos recently implemented a new algorithm to calculate locations of satellite-tracked animals that uses a Kalman filter (KF). The KF algorithm is reported to increase the number and accuracy of estimated positions over the traditional Least Squares (LS) algorithm, with potential advantages to the application of state-space methods to model animal movement data. We tested the performance of two Bayesian state-space models (SSMs) fitted to satellite tracking data processed with KF algorithm. Tracks from 7 harbour seals (Phoca vitulina) tagged with ARGOS satellite transmitters equipped with Fastloc GPS loggers were used to calculate the error of locations estimated from SSMs fitted to KF and LS data, by comparing those to “true” GPS locations. Data on 6 fin whales (Balaenoptera physalus) were used to investigate consistency in movement parameters, location and behavioural states estimated by switching state-space models (SSSM) fitted to data derived from KF and LS methods. The model fit to KF locations improved the accuracy of seal trips by 27% over the LS model. 82% of locations predicted from the KF model and 73% of locations from the LS model were <5 km from the corresponding interpolated GPS position. Uncertainty in KF model estimates (5.6±5.6 km) was nearly half that of LS estimates (11.6±8.4 km). Accuracy of KF and LS modelled locations was sensitive to precision but not to observation frequency or temporal resolution of raw Argos data. On average, 88% of whale locations estimated by KF models fell within the 95% probability ellipse of paired locations from LS models. Precision of KF locations for whales was generally higher. Whales’ behavioural mode inferred by KF models matched the classification from LS models in 94% of the cases. State-space models fit to KF data can improve spatial accuracy of location estimates over LS models and produce equally reliable behavioural estimates.