Silva, M.A., R. Prieto, I. Cascão, M.I. Seabra, M. Machete, M.F. Baumgartner, and R.S. Santos. 2014. Spatial and temporal distribution of cetaceans in the mid-Atlantic waters around the Azores. Marine Biology Research 10:123-137. PDF|
Palacios, D.M., M.F. Baumgartner, K.L. Laidre, and E.J. Gregr. 2013. Beyond correlation: integrating environmentally and behaviourally mediated processes in models of marine mammal distributions. Endangered Species Research 22:191-203. Conclusion to the ESR Theme Section Beyond Marine Mammal Habitat Modeling: Applications For Ecology And Conservation. PDF
Gregr, E.J., M.F. Baumgartner, K.L. Laidre, and D.M. Palacios. 2013 Marine mammal habitat models come of age: The emergence of ecological and management relevance. Endangered Species Research 22:205-212. Introduction to the ESR Theme Section Beyond Marine Mammal Habitat Modeling: Applications For Ecology And Conservation. PDF
Silva, M.A., R. Prieto, I. Jonsen, M.F. Baumgartner, and R.S. Santos. 2013. North Atlantic blue and fin whales suspend their spring migration to forage in middle latitudes: Building up energy reserves for the journey? PLoS ONE 8(10): e76507. doi:10.1371/journal.pone.0076507. PDF
Baumgartner, M.F., N.S.J. Lysiak, H.C. Esch, A.N. Zerbini, C.L. Berchok, and P.J. Clapham. 2013. Associations between North Pacific right whales and their zooplanktonic prey in the southeastern Bering Sea. Marine Ecology Progress Series 490:267-284. PDF
Baumgartner, M.F., D.M. Fratantoni, T.P. Hurst, M.W. Brown, T.V.N. Cole, S.M. Van Parijs, and M. Johnson. 2013. Real-time reporting of baleen whale passive acoustic detections from ocean gliders. Journal of the Acoustical Society of America 134:1814-1823. PDF
Miller, C.A., P.B. Best, W.L. Perryman, M.F. Baumgartner, and M.J. Moore. 2012. Body shape changes associated with reproductive status, nutritive condition and growth in right whales Eubalaena glacialis and Eubalaena australis. Marine Ecology Progress Series 459:135-156. PDF
Silva, M.A., L. Steiner, I. Cascão, M. João Cruz, R. Prieto, T. Cole, P.K. Hamilton, and M.F. Baumgartner. 2012. Winter sighting of a known western North Atlantic right whale in the Azores. Journal of Cetacean Research and Management 12:65–69. PDF
Newhall, A.E., Y-T. Lin, J.F. Lynch, M.F. Baumgartner, and G.G. Gawarkiewicz. 2012. An acoustic normal mode approach for long distance passive localization of vocalizing sei whales. Journal of the Acoustical Society of America 131:1814-1825. PDF
Aruda, A.M., M.F. Baumgartner, A.M. Reitzel, and A.M. Tarrant. 2011. Heat shock protein expression during stress and diapause in the marine copepod Calanus finmarchicus. Journal of Insect Physiology (Special Issue on Invertebrate Diapause) 57:665-675. PDF
Baumgartner, M.F. and S.E. Mussoline. 2011. A generalized baleen whale call detection and classification system. Journal of the Acoustical Society of America 129:2889-2902. PDF
Baumgartner, M.F., N.S.J. Lysiak, C. Schuman, J. Urban-Rich, and F.W. Wenzel. 2011. Diel vertical migration behavior of Calanus finmarchicus and its influence on right and sei whale occurrence. Marine Ecology Progress Series 423:167-184. PDF
Schick, R.S., P.N. Halpin, A.J. Read, C.K. Slay, S.D. Kraus, B.R. Mate, M.F. Baumgartner, J.J. Roberts, B.D. Best, C.P. Good, S.R. Loarie, and J.S. Clark. 2009. Striking the right balance in right whale conservation. Canadian Journal of Fisheries and Aquatic Sciences 66:1399-1403. PDF
Patrician, M.R., I.S. Biedron, H.C. Esch, F.W. Wenzel, L.A. Cooper, P.K. Hamilton, A.H. Glass, M.F. Baumgartner. 2009. Evidence of a North Atlantic right whale calf (Eubalaena glacialis) born in northeastern U.S. waters. Marine Mammal Science 25:462-477. PDF
Baumgartner, M.F., L. Freitag, J. Partan, K. Ball and K. Prada. 2008. Tracking large marine predators in three dimensions: the Real-time Acoustic Tracking System. IEEE Journal of Oceanic Engineering 33:146-157. PDF
Baumgartner, M.F. and D.M. Fratantoni. 2008. Diel periodicity in both sei whale vocalization rates and the vertical migration of their copepod prey observed from ocean gliders. Limnology and Oceanography 53: 2197-2209. PDF
Baumgartner, M.F., S.M. Van Parijs, F.W. Wenzel, C.J. Tremblay, H.C. Esch, and A.M. Warde. 2008. Low frequency vocalizations attributed to sei whales (Balaenoptera borealis). Journal of the Acoustical Society of America 124:1339-1349. PDF
Tarrant*, A.M., M.F. Baumgartner*, T. Verslycke, and C.L. Johnson. 2008. Differential gene expression in diapausing and active Calanus finmarchicus (Copepoda). Marine Ecology Progress Series 355:193-207. *These two authors made equal contributions to this paper. PDF
Baumgartner, M.F., C.A. Mayo, and R.D. Kenney. 2007. Enormous carnivores, microscopic food, and a restaurant that's hard to find. in S.D. Kraus and R.M. Rolland (eds). The Urban Whale: North Atlantic Right Whales at the Crossroads. Harvard University Press. PDF
Redfern, J.V., M.C. Ferguson, E.A. Becker, K.D. Hyrenbach, C. Good, J. Barlow, K. Kaschner, M.F. Baumgartner, K.A. Forney, L.T. Ballance, P. Fauchald, P. Halpin, T. Hamazaki, A.J. Pershing, S.S. Qian, A. Read, S.B. Reilly, L. Torres, and F. Werner. 2006. Techniques for cetacean-habitat modeling: A review. Marine Ecology Progress Series 310:271-295. PDF
Baumgartner, M.F. and B.R. Mate. 2005. Summer and fall habitat of North Atlantic right whales (Eubalaena glacialis) inferred from satellite telemetry. Canadian Journal of Fisheries and Aquatic Sciences 62:527-543. PDF
Baumgartner, M.F. 2003. Comparisons of Calanus finmarchicus fifth copepodite abundance estimates from nets and an optical plankton counter. Journal of Plankton Research 25:855-868. PDF
Baumgartner, M.F. and B.R. Mate. 2003. Summertime foraging ecology of North Atlantic right whales. Marine Ecology Progress Series 264:123-135. PDF
Baumgartner, M.F., T.V.N. Cole, P.J. Clapham and B.R. Mate. 2003. North Atlantic right whale habitat in the lower Bay of Fundy and on the SW Scotian Shelf during 1999-2001. Marine Ecology Progress Series. 264:137-154. PDF
Baumgartner, M.F., T.V.N. Cole, R.G. Campbell, G.J. Teegarden and E.G. Durbin. 2003. Associations between North Atlantic right whales and their prey, Calanus finmarchicus, over diel and tidal time scales. Marine Ecology Progress Series. 264:155-166. PDF
Durbin, E., G. Teegarden, R. Campbell, A. Cembella, M.F. Baumgartner and B.R. Mate. 2002. North Atlantic right whales, Eubalaena glacialis, exposed to paralytic shellfish poisoning (PSP) toxins via a zooplankton vector, Calanus finmarchicus. Harmful Algae 1:243-251. PDF
Baumgartner, M.F., K.D. Mullin, L.N. May and T.D. Leming. 2001. Cetacean habitats in the northern Gulf of Mexico. Fishery Bulletin 99:219-239. PDF
Baumgartner, M.F. and S.P. Anderson. 1999. Evaluation of regional numerical weather prediction model surface fields over the Middle Atlantic Bight. Journal of Geophysical Research 104:18,141-18,158. PDF
Anderson, S.P. and M.F. Baumgartner. 1998. Radiative heating errors in naturally ventilated air temperature measurements made from buoys. Journal of Atmospheric and Oceanic Technology 15:157-173. PDF
Davis, R.W., G.S. Fargion, L.N. May, T.D. Leming, M.F. Baumgartner, W.E. Evans, L.J. Hansen and K. Mullin. 1998. Physical habitat of cetaceans along the continental slope in the north-central and western Gulf of Mexico. Marine Mammal Science 14:490-507. PDF
Weller, R.A., M.F. Baumgartner, S.A. Josey, A.S. Fischer and J.C. Kindle. 1998. Atmospheric forcing in the Arabian Sea during 1994-1995: Observations and comparisons with climatology and models. Deep Sea Research II 45:1961-1999. PDF
Walsh, E.J., R. Pinkel, D.E. Hagan, R. A. Weller, C.W. Fairall, D.P. Rogers, S.P. Burns and M.F. Baumgartner. 1998. 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. Journal of Geophysical Research 103:12,613-12,628. PDF
Baumgartner, M.F. 1997. The distribution of Risso's dolphin (Grampus griseus) with respect to the physiography of the northern Gulf of Mexico. Marine Mammal Science 13:614-638. PDF
Silva, M.A., R. Prieto, I. Cascão, M.I. Seabra, M. Machete, M.F. Baumgartner, and R.S. Santos. 2014. Spatial and temporal distribution of cetaceans in the mid-Atlantic waters around the Azores. Marine Biology Research 10:123-137.
Cetaceans living in offshore waters are under increasing pressure from anthropogenic activities. Yet, due to the lack of survey effort, relatively little is known about the demography or ecology of these populations. Spatial and temporal distribution of cetaceans in mid-Atlantic waters were investigated using a long term dataset collected from boat surveys and land-based observations around the Azores. From 1999 to 2009, 7307 cetacean schools were sighted during 271,717 km of survey effort. In 4944 h of land-based observations, 2,968 cetacean groups were detected. Twenty-four species were recorded: seven baleen whales, six beaked whales, eight dolphin species, Physeter macrocephalus, Kogia breviceps and Kogia sima. Overall, Delphinus delphis was the most frequently sighted species, but its encounter rate decreased in June–November, coinciding with the presence of Stenella frontalis in the region. Tursiops truncatus, P. macrocephalus and Grampus griseus were frequently encountered year-round, whereas large baleen whales showed a distinct peak in encounter rates in March–May. Mesoplodonts were fairly common and appear to be present throughout the year. These findings fill in a significant gap in the knowledge of cetaceans occurring in a poorly studied region of the North Atlantic, providing much needed data to inform management initiatives.
Palacios, D.M., M.F. Baumgartner, K.L. Laidre, and E.J. Gregr. 2013. Beyond correlation: integrating environmentally and behaviourally mediated processes in models of marine mammal distributions. Endangered Species Research 22:191-203.
Marine species distribution modeling has seen explosive growth in recent years, and the Endangered Species Research Theme Section entitled ‘Beyond marine mammal habitat modeling: applications for ecology and conservation’ demonstrates that the field of marine mammalogy has been no exception. For the past decade, marine mammal ecologists have been developing habitat models with increasing proficiency and sophistication. However, these efforts have largely focused on correlative analyses of observed species-environment associations, which often have low explanatory power due to the absence of critical, but unaccounted for processes that are important drivers of animal distributions. Here we provide an overview of these processes, advocate for directed studies (e.g. tagging, prey sampling, focal follows, physiological assessment) to address how the processes influence species’ distributions, and challenge the modeling community to incorporate these results into their efforts. We also identify a progression of modeling stages from correlative to confirmatory to mechanistic that should lead us to formulate increasingly robust and accurate predictions of species distributions rooted in greater ecological understanding. Given the on-going risks to marine mammals from human activities and climate change, such models are needed for conservation and management now more than ever.
Gregr, E.J., M.F. Baumgartner, K.L. Laidre, and D.M. Palacios. 2013. Marine mammal habitat models come of age: The emergence of ecological and management relevance. Endangered Species Research 22:205-212.
Models for predicting marine mammal habitat are increasingly being developed to help answer questions about species’ ecology, conservation, and management. Over the past 10 yr, the models and analyses presented at the Habitat Modelling Workshops of the Biennial Conference on the Biology of Marine Mammals have shown tremendous development in their breadth and complexity. At the 18th Biennial, held in Quebec City, Canada, in 2009 we noticed a change in how these models were presented. Instead of a focus on methods and model development, many researchers presented models highlighting ecological insights or management applications. We recognised this as a watershed moment for our discipline, the time when we started paying more attention to what our models were telling us than how to build them. To celebrate this progress, we invited researchers from the global marine mammal community to submit articles to this Theme Section of Endangered Species Research describing work that included not only advanced model development, but also emphasised ecological interpretation or management relevance. The resulting collection of articles highlights the leading science in marine mammal habitat modelling, and provides some important indications of how, as a community, we must continue to refine our methods to move beyond correlations towards understanding the processes that interact to create marine mammal habitat. While there will no doubt be future challenges to overcome, the articles in this collection raise the standard for marine mammal habitat modelling, and herald the transition from learning how to model, to using our models as a heuristic tool to support ecological understanding and marine spatial planning.
Silva, M.A., R. Prieto, I. Jonsen, M.F. Baumgartner, and R.S. Santos. 2013. North Atlantic blue and fin whales suspend their spring migration to forage in middle latitudes: Building up energy reserves for the journey? PLoS ONE 8(10): e76507. doi:10.1371/journal.pone.0076507.
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.
Baumgartner, M.F., N.S.J. Lysiak, H.C. Esch, A.N. Zerbini, C.L. Berchok, and P.J. Clapham. 2013. Associations between North Pacific right whales and their zooplanktonic prey in the southeastern Bering Sea. Marine Ecology Progress Series 490:267-284.
Due to the seriously endangered status of North Pacific right whales Eubalaena japonica, an improved understanding of the environmental factors that influence the species’ distribution and occurrence is needed to better assess the effects of climate change and industrial activities on the population. Associations among right whales, zooplankton, and the physical environment were examined in the southeastern Bering Sea during the summers of 2008 and 2009. Sampling with nets, an optical plankton counter, and a video plankton recorder in proximity to whales as well as along cross-isobath surveys indicated that the copepod Calanus marshallae is the primary prey of right whales in this region. Acoustic detections of right whales from sonobuoys deployed during the cross-isobath surveys were strongly associated with C. marshallae abundance, and peak abundance estimates of C. marshallae in 2.5 m depth strata near a tagged right whale ranged as high as 106 copepods m-3. The smaller Pseudocalanus spp. was higher in abundance than C. marshallae in proximity to right whales, but significantly lower in biomass. High concentrations of C. marshallae occurred in both the surface and bottom layers of the highly stratified water column, but there was no evidence of diel vertical migration. Instead, occurrence of C. marshallae in the bottom layer was associated with elevated near-bottom light attenuance and chlorophyll fluorescence, suggesting C. marshallae may aggregate at depth while feeding on resuspended phytodetritus. Despite the occasional presence of strong horizontal gradients in hydrographic properties, no association was found between C. marshallae and either fronts or phytoplankton distribution.
Baumgartner, M.F., D.M. Fratantoni, T.P. Hurst, M.W. Brown, T.V.N. Cole, S.M. Van Parijs, and M. Johnson. 2013. Real-time reporting of baleen whale passive acoustic detections from ocean gliders. Journal of the Acoustical Society of America 134:1814-1823.
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-minute 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 10 cases when whales were sighted during aerial or shipboard surveys and a glider was within 20 km of the sighting location, 9 were accompanied by real-time acoustic detections of the same species by the glider within ±12 hours of the sighting time.
Miller, C.A., P.B. Best, W.L. Perryman, M.F. Baumgartner, and M.J. Moore. 2012. Body shape changes associated with reproductive status, nutritive condition and growth in right whales Eubalaena glacialis and Eubalaena australis. Marine Ecology Progress Series 459:135-156 .
Mammalian reproduction is metabolically regulated; therefore, the endangered status and high variability in reproduction of North Atlantic right whales Eubalaena glacialis necessitate accurate assessments at sea of the nutritional condition of living individuals. Aerial photogrammetry was used to measure dorsal body width at multiple locations along the bodies of free-swimming right whales at different stages of the female reproductive cycle (E. glacialis) and during the initial months of lactation (mother and calf Eubalaena australis) to quantify changes in nutritional condition during energetically demanding events. Principal components analyses indicated that body width was most variable at 60% of the body length from the snout. Thoracic, abdominal and caudal body width of E. australis thinned significantly during the initial months of lactation, especially at 60% of body length from the snout, while their calves’ widths and width-to-length ratios increased. The body shape of E. glacialis that had been lactating for 8 mo was significantly thinner than non-lactating, non-pregnant E. glacialis. Body shape of E. glacialis measured in the eighth month of lactation was significantly thinner than that of E. australis in the first month, but did not differ from that of E. australis in the third and fourth months. Body width was comparable with diameter calculated from girth of carcasses. These results indicate that mother right whales rely on endogenous nutrient reserves to support the considerable energy expenditure during the initial months of lactation; therefore, photogrammetric measurements of body width, particularly at 60% of body length from the snout, are an effective way to quantitatively and remotely assess nutritional condition of living right whales.
Silva, M.A., L. Steiner, I. Cascão, M. João Cruz, R. Prieto, T. Cole, P.K. Hamilton, and M.F. Baumgartner. 2012. Winter sighting of a known western North Atlantic right whale in the Azores. Journal of Cetacean Research and Management 12:65–69.
A right whale (Eubalaena glacialis) from the western North Atlantic population, sighted in the Azores, was subsequently found to have moved back to the northwest Atlantic. The whale was sighted in the Azores on 5 January 2009 travelling in a west-south westerly direction at a constant speed. A photographic match was found to an adult female in the North Atlantic Right Whale Catalogue. The whale’s previous last sighting, on 24 September 2008 in the Bay of Fundy, Canada, implies movement to the Azores of at least 3,320km in 101 days. It was subsequently resighted in the Bay of Fundy on 2 September 2009, 237 days after being seen in the Azores. This appears to be the only documented evidence of a western North Atlantic right whale outside its normal range in winter, and provides additional evidence of the potential for interbreeding between western North Atlantic right whales and the remnant eastern population.
Newhall, A.E., Y-T. Lin, J.F. Lynch, M.F. Baumgartner, and G.G. Gawarkiewicz. 2012. An acoustic normal mode approach for long distance passive localization of vocalizing sei whales. Journal of the Acoustical Society of America 131:1814-1825.
During a 2 day period in mid-September 2006, more than 200, unconﬁrmed but identiﬁable, sei whale (Balaenoptera borealis) calls were collected as incidental data during a multidisciplinary oceanography and acoustics experiment on the shelf off New Jersey. Using a combined vertical and horizontal acoustic receiving array, sei whale movements were tracked over long distances (up to tens of kilometers) using a normal mode back propagation technique. This approach uses low-frequency, broadband passive sei whale call receptions from a single-station, two-dimensional hydrophone array to perform long distance localization and tracking by exploiting the dispersive nature of propagating normal modes in a shallow water environment. The back propagation approach is examined for accuracy and application to tracking the sei whale vocalizations identiﬁed in the vertical and horizontal array signals. This passive whale tracking, combined with the intensive oceanography measurements performed during the experiment, was also used to examine sei whale movements in relation to oceanographic features observed in this region.
Aruda, A.M. , M.F. Baumgartner, A.M. Reitzel, and A.M. Tarrant. 2011. Heat shock protein expression during stress and diapause in the marine copepod Calanus ﬁnmarchicus. Journal of Insect Physiology (Special Issue on Invertebrate Diapause) 57:665-675.
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.
Baumgartner, M.F. and S.E. Mussoline. 2011. A generalized baleen whale call detection and classification system. Journal of the Acoustical Society of America 129:2889-2902.
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.
Baumgartner, M,F., N.S.J. Lysiak, C. Schuman, J. Urban-Rich, and F.W. Wenzel. 2011. Diel vertical migration behavior of Calanus finmarchicus and its influence on right and sei whale occurrence. Marine Ecology Progress Series 423:167-184.
Diel vertical migration (DVM) by herbivorous copepods likely has a profound effect on the behavior and ecology of copepod predators. We characterized the DVM behavior of late-stage Calanus finmarchicus in the southwestern Gulf of Maine during the spring seasons of 2005 to 2007, and investigated the influence of this behavior on the occurrence of zooplanktivorous baleen whales. On 5 occasions, we occupied an oceanographic station for 1 to 2 d and conducted (1) a half-hourly census of whales and (2) a half-hourly cast with an instrument package measuring temperature, salinity, chlorophyll fluorescence, and copepod abundance. We observed significant variability in DVM behavior both within and among years that was unrelated to stratification or chlorophyll concentration. Instead, DVM appeared to be influenced by the vertical distribution of phytoplankton, the presence of visual predators (sand lance Ammodytes spp.), copepod developmental stage, and the feeding history of individual copepods. Migrating copepods had oil sacs that were 44% larger than non-migrating copepods at the surface after accounting for developmental stage, which suggests that well-fed copepods are more likely to vertically migrate. While the occurrence of North Atlantic right whales Eubalaena glacialis was unrelated to variability in the migration behavior of C. finmarchicus, sei whales Balaenoptera borealis were significantly less abundant during times of strong DVM behavior. We speculate that right whales do not compete directly with sand lance and herring for C. finmarchicus, but by inducing DVM behavior, these fish are likely influencing the distribution and abundance of sei whales in the southwestern Gulf of Maine.
Schick, R.S., P.N. Halpin, A.J. Read, C.K. Slay, S.D. Kraus, B.R. Mate, M.F. Baumgartner, J.J. Roberts, B.D. Best, C.P. Good, S.R. Loarie, and J.S. Clark. 2009. Striking the right balance in right whale conservation. Canadian Journal of Fisheries and Aquatic Sciences 66:1399-1403.
Despite many years of study and protection, the North Atlantic right whale (Eubalaena glacialis) remains on the brink of extinction. There is a crucial gap in our understanding of their habitat use in the migratory corridor along the eastern seaboard of the United States. Here, we characterize habitat suitability in migrating right whales in relation to depth, distance to shore, and the recently enacted ship speed regulations near major ports. We find that the range of suitable habitat exceeds previous estimates and that, as compared with the enacted 20 nautical mile buffer, the originally proposed 30 nautical mile buffer would protect more habitat for this critically endangered species.
Baumgartner, M.F., L. Freitag, J. Partan, K. Ball and K. Prada. 2008. Tracking large marine predators in three dimensions: the Real-time Acoustic Tracking System. IEEE Journal of Oceanic Engineering 33:146-157.
Large marine predators like sharks and whales can have a substantial influence on oceanic ecosystems, and characterizing their interactions with the physical and biological environment is an important goal in marine ecology. Studies of foraging ecology are of particular importance, but sampling prey aggregations encountered by these predators is extremely difficult because of the small spatial scales over which prey aggregations often occur (meters to hundreds of meters). We developed the real-time acoustic tracking system (RATS) to allow large marine predators to be accurately tracked over these small spatial scales to facilitate proximate environmental sampling. The system consists of an array of four free-floating buoys capable of detecting 36-kHz pings emitted by an animal-borne acoustic transmitter. Upon detection, the buoys transmit their position and the arrival time of the ping via a radio modem to a computer on board a nearby ship, and a software program uses differences in arrival times from all of the buoys to estimate the location of the tagged animal. The positions of the tagged animal, buoys, ship, and support boats can be monitored via a graphical user interface to allow proximate environmental sampling and maintenance of the array around the tagged animal. In situ tests indicate that average positional accuracies for a transmitter inside either a four- or three-buoy array (buoys spaced 1–1.75 km apart) are less than 10 m, and that accuracies remain near 10 m for transmitters located up to 500 m away from the edge of the array. The buoys can consistently detect the transmitter up to 1000 m away, but detection rates decrease between 1000 and 2000 m; no detections were obtained beyond 2300 m. Field deployments of the system have demonstrated an unprecedented ability to monitor the movements of baleen whales in real time, allowing a suite of prey and oceanographic observations to be collected within meters to tens of meters of a tagged animal.
Baumgartner, M.F. and D.M. Fratantoni. 2008. Diel periodicity in both sei whale vocalization rates and the vertical migration of their copepod prey observed from ocean gliders. Limnology and Oceanography 53: 2197-2209.
The daily activity cycles of marine predators may be dictated in large part by the timing of prey availability. For example, recent studies have observed diel periodicity in baleen whale vocalization rates that are thought to be governed by the diel vertical migration of their zooplanktonic prey. We addressed this hypothesis by studying associations between sei whale (Balaenoptera borealis) vocalization rates, oceanographic conditions, and the vertical distribution of the whales’ prey, the calanoid copepod Calanus finmarchicus, during May 2005 in the southwestern Gulf of Maine using an array of autonomous ocean gliders. Each of the four gliders was equipped with sensors to measure temperature, salinity, and chlorophyll fluorescence. Three of the four gliders carried a digital acoustic recorder and the fourth carried a 1-MHz acoustic Doppler current profiler. We observed strong diel periodicity in the acoustic backscatter measured by the current profiler that we attribute (based on a corroborating shipboard study) to the diel vertical migration of C. finmarchicus. Sei whale vocalization rates also exhibited diel periodicity, with more calls detected during the daytime when C. finmarchicus was observed at depth. We found no evidence to suggest that the observed patterns in sei whale calling rates were attributable to diel periodicity in background noise or acoustic propagation conditions. Sei whales are adept at foraging on near-surface aggregations of C. finmarchicus; therefore we expect that the whales were feeding at night. We hypothesize that calling rates are reduced at night while the whales are feeding, but increase with social activity during the day when copepods are either more difficult or less efficient to capture at depth. The gliders’ persistence during adverse weather conditions experienced during the study allowed continuous collocated observations of whale vocalization behavior and oceanographic conditions that have not been previously possible with traditional shipboard techniques.
Baumgartner, M.F., S.M. Van Parijs, F.W. Wenzel, C.J. Tremblay, H.C. Esch, and A.M. Warde. 2008. Low frequency vocalizations attributed to sei whales (Balaenoptera borealis). Journal of the Acoustical Society of America 124:1339-1349.
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.
Tarrant, A.M., M.F. Baumgartner, T. Verslycke, and C.L. Johnson. 2008. Differential gene expression in diapausing and active Calanus finmarchicus (Copepoda). Marine Ecology Progress Series 355:193-207.
To survive long periods of low food availability, some calanoid copepods have a life history that includes a diapause phase during which copepodids delay development to adulthood, migrate to depth, reduce metabolism, and utilize stored lipids for nourishment. While seasonal patterns in diapause have been described, the environmental and physiological regulation of diapause has not been elucidated. We collected Calanus finmarchicus C5 copepodids from surface (0 to 39 m) and deep (157 to 201 m) waters in the Gulf of Maine, and both morphological and biochemical measurements indicated that these copepodids were from active and diapausing populations, respectively. Two complementary molecular techniques were used to compare gene expression in these 2 groups: (1) suppressive subtractive hybridization (SSH) was used to identify genes that may be differentially expressed, and (2) quantitative real-time RT-PCR was used to characterize patterns of gene expression in individual copepodids. Three genes associated with lipid synthesis, transport and storage (ELOV, FABP, RDH) were upregulated (more highly expressed)in active copepods, particularly those with small oil sacs. Expression of ferritin was greater in diapausing copepods with large oil sacs, consistent with a role of ferritin in chelating metals to protect cells from oxidative stress and/or delay development. Ecdysteroid receptor (EcR) expression was greater in diapausing copepods, highlighting the need for further investigation into endocrine regulation of copepod development. This study represents the first molecular characterization of gene expression associated with calanoid copepod diapause and provides a foundation for future investigations of the underlying mechanisms that regulate diapause.
Redfern, J.V., M.C. Ferguson, E.A. Becker, K.D. Hyrenbach, C. Good, J. Barlow, K. Kaschner, M.F. Baumgartner, K.A. Forney, L.T. Ballance, P. Fauchald, P. Halpin, T. Hamazaki, A.J. Pershing, S.S. Qian, A. Read, S.B. Reilly, L. Torres, and F. Werner. 2006. Techniques for cetacean-habitat modeling: A review. Marine Ecology Progress Series 310:271-295.
Cetacean-habitat modeling, although still in the early stages of development, represents a potentially powerful tool for predicting cetacean distributions and understanding the ecological processes determining these distributions. Marine ecosystems vary temporally on diel to decadal scales and spatially on scales from several meters to 1000s of kilometers. Many cetacean species are wide-ranging and respond to this variability by changes in distribution patterns. Cetacean-habitat models have already been used to incorporate this variability into management applications, including improvement of abundance estimates, development of marine protected areas, and understanding cetacean-fisheries interactions. We present a review of the development of cetacean-habitat models, organized according to the primary steps involved in the modeling process. Topics covered include purposes for which cetacean-habitat models are developed, scale issues in marine ecosystems, cetacean and habitat data collection, descriptive and statistical modeling techniques, model selection, and model evaluation. To date, descriptive statistical techniques have been used to explore cetacean-habitat relationships for selected species in specific areas; the numbers of species and geographic areas examined using computationally intensive statistic modeling techniques are considerably less, and the development of models to test specific hypotheses about the ecological processes determining cetacean distributions has just begun. Future directions in cetacean-habitat modeling span a wide range of possibilities, from development of basic modeling techniques to addressing important ecological questions.
Baumgartner, M.F. and B.R. Mate. 2005. Summer and fall habitat of North Atlantic right whales (Eubalaena glacialis) inferred from satellite telemetry. Canadian Journal of Fisheries and Aquatic Sciences 62:527-543.
Satellite-monitored radio tags were attached to North Atlantic right whales (Eubalaena glacialis) in Grand Manan Basin of the lower Bay of Fundy during the summer and early fall seasons of 1989-1991 and 2000. Monte Carlo tests were used to examine the distribution of the tagged whales in space and time and with respect to a variety of environmental variables to characterize right whale habitat on their northern feeding grounds. These environmental variables included depth, depth gradient, climatological surface and bottom hydrographic properties, and remotely sensed surface temperature, chlorophyll concentration, and their respective horizontal gradients. Site fidelity in the Bay of Fundy was very low during 1989-1991 and high during 2000. When the tagged animals left the Bay, they did not frequently visit the deep basins of the Gulf of Maine and Scotian Shelf, where abundances of their primary copepod prey, Calanus finmarchicus, are thought to be high. Instead, right whales visited areas characterized by low bottom water temperatures, high surface salinity, and high surface stratification. No evidence was found that the tagged right whales associated with oceanic fronts or regions with high standing stocks of phytoplankton.
Baumgartner, M.F. 2003. Comparisons of Calanus finmarchicus fifth copepodite abundance estimates from nets and an optical plankton counter. Journal of Plankton Research 25:855-868.
The response of an optical plankton counter (OPC) to concentrations of Calanus finmarchicus fifth copepodites (C5) ranging from 2 to 1621 copepods m-3 was examined during the summers of 1999-2001 over the continental shelf of the northwest Atlantic Ocean. Net tows from either a bongo net or a multiple opening/closing net and environmental sensing system (MOCNESS) were collocated with vertical OPC casts to provide comparable data. OPC-derived particle abundance in the 1.5-2.0 mm equivalent circular diameter range was strongly correlated with net-derived abundance of C. finmarchicus C5 (r2 = 0.655 and 0.726 for comparisons in two independent datasets). Particle abundance in this size range increased with increases in the descent speed of the vertically profiled OPC, which indicated avoidance of the small sampling aperture by C. finmarchicus C5. A regression model was developed to relate OPC particle abundance in the 1.5-2.0 mm size range to the abundance of C. finmarchicus C5 and the descent speed of the OPC. The data fitted the model well (r2 = 0.684) and the inverted model was used as a calibration equation to predict C. finmarchicus C5 abundances from OPC measurements in an independent comparison to net abundances. In that case, the calibration equation underestimated net abundance by an average factor of 2. However, anomalously low OPC particle abundances for some casts suggest that spatial heterogeneity (patchiness) can confound such comparisons.
Baumgartner, M.F. and B.R. Mate. 2003. Summertime foraging ecology of North Atlantic right whales. Marine Ecology Progress Series 264:123-135.
North Atlantic right whales were instrumented with suction-cup mounted, time-depth recorders (TDR) during the summers of 2000 and 2001 to examine their diving and foraging behavior. Simultaneous observations of temperature, salinity and the vertical distribution of their principal prey, Calanus finmarchicus stage 5 copepodites (C5), were obtained along each whaleís track with a conductivity-temperature-depth instrument (CTD) and an optical plankton counter (OPC). Right whale feeding dives were characterized by rapid descent from the surface to a particular depth between 80 and 175 m, remarkable fidelity to that depth for 5 to 14 min and then rapid ascent back to the surface. The average depth of dive was strongly and positively correlated with both the average depth of peak C. finmarchicus C5 abundance and the average depth of the bottom mixed layer's upper surface. Significantly longer surface intervals were observed for reproductively active females and their calves when compared to other individuals, indicating that this critical segment of the population may be at increased risk of ship strikes owing to their diving behavior. Ingestion rates calculated from TDR and OPC data exceeded estimated daily metabolic requirements for most of the tagged right whales; however, short deployment durations and uncertainty in metabolic rates make it impossible to judge whether individual right whales were obtaining sufficient energy to meet the metabolic costs of reproduction. Improvements in attachment durations and the development of novel methods to estimate the metabolic rates of large whales in situ are required to determine whether right whale reproduction is limited by insufficient food resources.
Baumgartner, M.F., T.V.N. Cole, P.J. Clapham and B.R. Mate. 2003. North Atlantic right whale habitat in the lower Bay of Fundy and on the SW Scotian Shelf during 1999-2001. Marine Ecology Progress Series. 264:137-154.
Simultaneous visual and oceanographic surveys were conducted in the lower Bay of Fundy and in Roseway Basin of the SW Scotian Shelf during the summers of 1999 to 2001 to investigate the physical and biological oceanographic factors associated with North Atlantic right whale occurrence. Sightings of right whales were recorded along predetermined transects through each region, while both in situ and remotely sensed oceanographic measurements were collected. Sampling with plankton nets and an optical plankton counter confirmed that right whales in these regions feed on Calanus finmarchicus copepodite stage 5 (C5). Spatial variability in right whale occurrence was associated with water depth and the depth of the bottom mixed layer. C. finmarchicus C5 aggregated over the deepest water depths in both regions, and within these areas, right whales occurred where the bottom mixed layer forced discrete layers of C. finmarchicus C5 to occur shallower in the water column (allowing more efficient foraging). Annual increases in right whale occurrence appeared to be associated with decreases in sea surface temperature (SST) in both regions; however, this observation merits caution in light of the short duration of the study (3 yr). There was also evidence to suggest that both spatial and interannual variability in right whale occurrence in Roseway Basin may be associated with SST gradient, a proxy for ocean fronts.
Baumgartner, M.F., T.V.N. Cole, R.G. Campbell, G.J. Teegarden and E.G. Durbin. 2003. Associations between North Atlantic right whales and their prey, Calanus finmarchicus, over diel and tidal time scales. Marine Ecology Progress Series. 264:155-166.
Temporal variability in the distribution and abundance of North Atlantic right whales Eubalaena glacialis and their copepod prey, late-stage Calanus finmarchicus, was monitored at an oceanographic station in Grand Manan Basin of the lower Bay of Fundy for 29 h on 2 separate occasions. The vertical distribution of C. finmarchicus was measured at 1/2 h intervals with an optical plankton counter (OPC) and at 6 or 12 h intervals with a MOCNESS. Right whale abundance was estimated from periodic point scans. Late-stage C. finmarchicus exhibited diel vertical migration in the upper 100 m of the water column, but the bulk of the population remained at depths below 100 m throughout both the day and night and was likely in diapause. Diel vertical migration is unlikely to be influenced by right whales, but may instead be motivated by abundant, near-surface food resources and avoidance of visual predators. Right whale sighting rate was correlated with OPC-detected C. finmarchicus fifth copepodite (C5) abundance at mid-depths (90-140 m); variability in both right whale sighting rate and C. finmarchicus C5 abundance in this depth stratum appeared to have similar periodicity to that of the tide. Energetic considerations suggest that right whales continue to feed on deep, diapausing layers of C. finmarchicus during the night, but the occasional presence of exploitable near-surface concentrations of C. finmarchicus suggests that nighttime near-surface feeding might sometimes occur.
Durbin, E., G. Teegarden, R. Campbell, A. Cembella, M.F. Baumgartner and B.R. Mate. 2002. North Atlantic right whales, Eubalaena glacialis, exposed to paralytic shellfish poisoning (PSP) toxins via a zooplankton vector, Calanus finmarchicus. Harmful Algae 1:243-251.
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 for 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.
Baumgartner, M.F., K.D. Mullin, L.N. May and T.D. Leming. 2001. Cetacean habitats in the northern Gulf of Mexico. Fishery Bulletin 99:219-239.
Surveys were conducted in the northern Gulf of Mexico during the spring seasons of 1992, 1993 and 1994 to determine the distribution, abundance and habitat preferences of oceanic cetaceans. The distributions of bottlenose dolphins (Tursiops truncatus), Rissoís dolphins (Grampus griseus), Kogia spp. [pygmy (Kogia breviceps) and dwarf sperm whales (Kogia sima)], pantropical spotted dolphins (Stenella attenuata) and sperm whales (Physeter macrocephalus) were examined with respect to depth, depth gradient, surface temperature, surface temperature variability, the depth of the 15 degree Celcius isotherm, surface chlorophyll concentration and epipelagic zooplankton biomass. Bottlenose dolphins were encountered in two distinct regions: the shallow continental shelf (0 - 150 m) and just seaward of the shelf break (200 - 750 m). Within both of these depth strata, bottlenose dolphins were sighted more frequently than expected in regions of high surface temperature variability which suggests an association with ocean fronts. Rissoís dolphins were encountered over the steeper sections of the upper continental slope (200 - 1000 m) while the Kogia spp. were sighted more frequently in waters of the upper continental slope that had high zooplankton biomass. The pantropical spotted dolphin and sperm whale were similarly distributed over the lower continental slope and deep Gulf (> 1000 m), but sperm whales were generally absent from anticyclonic oceanographic features (e.g., the Loop Current, warm-core eddies) characterized by deep occurrences of the 15 degree Celcius isotherm. Habitat partitioning, high-use areas, species accounts, environmental sampling limitations and directions for future habitat work in the Gulf of Mexico are discussed.
Baumgartner, M.F. and S.P. Anderson. 1999. Evaluation of regional numerical weather prediction model surface fields over the Middle Atlantic Bight. Journal of Geophysical Research 104:18,141-18,158.
Coastal ocean models often rely on the surface fields from numerical weather prediction (NWP) models for realistic surface boundary conditions, but the errors in these fields are poorly understood. We evaluate the surface meteorological and flux fields provided by three of the regional NWP models in operation during 1996 and 1997 at the U.S. National Centers for Environmental Prediction (NCEP): the Eta-48, Eta-29 and Rapid Update Cycle (RUC-1) models. These model fields are compared to in-situ measurements made from an air-sea interaction buoy deployed from July 1996 to June 1997 at a mid-shelf location in the Middle Atlantic Bight during the Coastal Mixing and Optics (CMO) experiment. In addition, data from six National Data Buoy Center buoys are used to evaluate spatial errors in the model fields. The Eta-29 and RUC-1 models overestimate the net ocean-to-atmosphere heat flux by an average 83 and 74 W m-2, respectively, with notable errors in each of the individual heat flux components. The poorly resolved SST fields used in the 1996-1997 regional NWP models lead to significant errors in the latent and sensible heat fluxes over the continental shelf and slope. Moreover, wind speeds are slightly overestimated in the Eta-48 and Eta-29 models while the RUC-1 model underestimates them by over 1 m s-1. All of the models have mean wind direction errors of 7 to 13 degrees east of north. In light of these evaluations, considerations for improving the accuracy of the surface flux fields for use in future ocean modeling studies are discussed.
Anderson, S.P. and M.F. Baumgartner. 1998. Radiative heating errors in naturally ventilated air temperature measurements made from buoys. Journal of Atmospheric and Oceanic Technology 15:157-173.
Solar radiative heating errors in buoy mounted, naturally ventilated air temperature sensors are examined. Data from sensors with multi-plate 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 0.27C and maximum instantaneous errors of 3.4C. 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 occurring at elevations of approximately 45 degrees. A simple model of sensor heating that balances the radiative heating with convective and conductive cooling is presented. This model can be used with empirically determined coefficients and observations of wind speed and shortwave radiation to quantify the radiative heating errors in naturally ventilated air temperature sensors.
Davis, R.W., G.S. Fargion, L.N. May, T.D. Leming, M.F. Baumgartner, W.E. Evans, L.J. Hansen and K. Mullin. 1998. Physical habitat of cetaceans along the continental slope in the north-central and western Gulf of Mexico. Marine Mammal Science 14:490-507.
The physical habitat of cetaceans found along the continental slope in the north-central and western Gulf of Mexico was characterized from shipboard sighting data, simultaneous hydrographic measurements, and satellite remote sensing. The study area was encompassed by the longitude of the Florida-Alabama border (87.5W), the southernmost latitude of the Texas-Mexico border (26.0N), and the 100-m and 2,000-m isobaths. Shipboard surveys were conducted seasonally for two years from April 1992 to May 1994. A total of 21,350 km of transect was visually sampled in an area of 154,621 km2.
Sighting localities of species in the study area were differentiated most clearly with bottom depth. Atlantic spotted dolphins (Stenella frontalis) were consistently found in the shallowest water on the continental shelf and along the shelf break. In addition, the bottom depth gradient (sea floor slope) was less for Atlantic spotted dolphins than for any other species. Bottlenose dolphins (Tursiops truncatus) were found most commonly along the upper slope in water significantly deeper than that for Atlantic spotted dolphins. All the other species and species categories were found over deeper bottom depths; these were Risso's dolphins (Grampus griseus), short-finned pilot whales (Globicephala macrorhynchus), pygmy/dwarf sperm whales (Kogia spp.), rough-toothed dolphins (Steno bredanensis), spinner dolphins (Stenella longirostris), sperm whales (Physeter macrocephalus), striped dolphins (Stenella coeruleoalba), Mesoplodon spp., pantropical spotted dolphins (Stenella attenuata), Clymene dolphins (Stenella clymene) and unidentified beaked whales (Ziphiidae). Risso's dolphins and short-finned pilot whales occurred along the upper slope and, as a subgroup, were significantly different from striped dolphins, Mesoplodon spp., pantropical spotted dolphins, Clymene dolphins, and unidentified beaked whales, which occurred in the deepest water. Pygmy/dwarf sperm whales, rough-toothed dolphins, spinner dolphins, and sperm whales occurred at intermediate depths between these two subgroups and overlapped them.
Weller, R.A., M.F. Baumgartner, S.A. Josey, A.S. Fischer and J.C. Kindle. 1998. Atmospheric forcing in the Arabian Sea during 1994-1995: Observations and comparisons with climatology and models. Deep Sea Research II 45:1961-1999.
Accurate, year-long time series of winds, incoming shortwave and longwave radiation, air and sea temperatures, relative humidity, barometric pressure, and precipitation have been 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.
Walsh, E.J., R. Pinkel, D.E. Hagan, R. A. Weller, C.W. Fairall, D.P. Rogers, S.P. Burns and M.F. Baumgartner. 1998. 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. Journal of Geophysical Research 103:12,613-12,628.
Patterns in sea surface temperature (SST) on 5-km scales were observed from low-flying research aircraft on a light wind day during the TOGA 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.
Baumgartner, M.F. 1997. The distribution of Risso's dolphin (Grampus griseus) with respect to the physiography of the northern Gulf of Mexico. Marine Mammal Science 13:614-638.
The distribution of Risso's dolphin (Grampus griseus) was examined with respect to two physiographic variables, water depth and depth gradient (sea floor slope), in the northern Gulf of Mexico using shipboard and aerial survey data collected from 1992 to 1994. Univariate chi-squared analyses demonstrated that Risso's dolphins are distributed non-uniformly with respect to both depth and depth gradient. A bivariate analysis of the shipboard data indicated that Risso's dolphins utilize the steep sections of the upper continental slope in the northern Gulf of Mexico. This narrow, core habitat is in waters bounded by the 350m and 975m isobaths with depth gradients greater than 24m per 1.1km and consists of only 2% of the surface area of the entire Gulf of Mexico. Sighting rates inside this region were nearly 5 and 6 times the average for the shipboard and aerial surveys, respectively. Of the groups sighted outside this region, 40% (shipboard) and 73% (aerial) were encountered within 5km of it. Since it is unlikely that the physiography alone can attract dolphins, oceanographic mechanisms that may concentrate prey along the steep upper continental slope are discussed. The implications of this distribution including potential prey species, foraging strategies and impacts of proposed mineral exploration and development are also considered.