Crocker, Daniel E.http://hdl.handle.net/10211.1/14062024-03-28T12:11:42Z2024-03-28T12:11:42ZThe Effect of a Low-Frequency Sound Source (Acoustic Thermometry of the Ocean Climate) on the Diving Behavior of Juvenile Northern Elephant Seals, Mirounga angustirostrisCosta, Daniel P.Crocker, Daniel E.Gedamke, JasonWebb, Paul M.Houser, Dorian S.Blackwell, Susanna B.Waples, DanielleHayes, Sean A.Le Boeuf, Burney J.http://hdl.handle.net/10211.3/1247202019-12-12T20:37:05Z2003-02-01T00:00:00ZThe Effect of a Low-Frequency Sound Source (Acoustic Thermometry of the Ocean Climate) on the Diving Behavior of Juvenile Northern Elephant Seals, Mirounga angustirostris
Costa, Daniel P.; Crocker, Daniel E.; Gedamke, Jason; Webb, Paul M.; Houser, Dorian S.; Blackwell, Susanna B.; Waples, Danielle; Hayes, Sean A.; Le Boeuf, Burney J.
Changes in the diving behavior of individual free-ranging juvenile northern elephant seals,
Mirounga angustirostris, exposed to the acoustic thermometry of the ocean climate (ATOC) sound
source were examined using data loggers. Data loggers were attached to the animals and measured
swim speed, maximum depth of dive, dive duration, surface interval, descent and ascent rate, and
descent and ascent angle along with sound pressure level (SPL). The ATOC sound source was at a
depth of 939 m and transmitted at 195 dB re: 1µPa at 1 m centered at 75 Hz with a 37.5-Hz
bandwidth. Sound pressure levels (SPL) measured at the seal during transmissions averaged 128 dB
and ranged from 118 to 137 dB re: 1 µPa for the 60–90 Hz band, in comparison to ambient levels
of 87–107 dB within this band. In no case did an animal end its dive or show any other obvious
change in behavior upon exposure to the ATOC sound. Subtle changes in diving behavior were
detected, however. During exposure, deviations in descent rate were greater than 1 s.d. of the control
mean in 9 of 14 seals. Dive depth increased and descent velocity increased in three animals, ascent
velocity decreased in two animals, ascent rate increased in one animal and decreased in another, and
dive duration decreased in only one animal. There was a highly significant positive correlation
between SPL and descent rate. The biological significance of these subtle changes is likely to be
minimal. This is the first study to quantify behavioral responses of an animal underwater with
simultaneous measurements of SPL of anthropogenic sounds recorded at the animal.
Published by and copyright of AIP Publishing. The definitive version of this article is available at: http://scitation.aip.org/content/asa/journal/jasa/113/2/10.1121/1.1538248
2003-02-01T00:00:00ZA Non-Traditional Model of the Metabolic Syndrome: The Adaptive Significance of Insulin in Fasting-Adapted SealsHouser, Dorian S.Champagne, Cory D.Crocker, Daniel E.http://hdl.handle.net/10211.3/1232412014-10-02T09:26:11Z2013-11-01T00:00:00ZA Non-Traditional Model of the Metabolic Syndrome: The Adaptive Significance of Insulin in Fasting-Adapted Seals
Houser, Dorian S.; Champagne, Cory D.; Crocker, Daniel E.
Insulin resistance in modern society is perceived as a pathological consequence of excess
energy consumption and reduced physical activity. Its presence in relation to the development
of cardiovascular risk factors has been termed the metabolic syndrome, which
produces increased mortality and morbidity and which is rapidly increasing in human populations.
Ironically, insulin resistance likely evolved to assist animals during food shortages
by increasing the availability of endogenous lipid for catabolism while protecting protein
from use in gluconeogenesis and eventual oxidation. Some species that incorporate fasting
as a predictable component of their life history demonstrate physiological traits similar
to the metabolic syndrome during prolonged fasts. One such species is the northern elephant
seal (Mirounga angustirostris), which fasts from food and water for periods of up
to 4 months. During this time, s90% of the seals metabolic demands are met through
fat oxidation and circulating non-esterified fatty acids are high (0.7–3.2 mM). All life history
stages of elephant seal studied to date demonstrate insulin resistance and fasting hyperglycemia
as well as variations in hormones and adipocytokines that reflect the metabolic
syndrome to some degree. Elephant seals demonstrate some intriguing adaptations with
the potential for medical advancement; for example, ketosis is negligible despite significant
and prolonged fatty acid oxidation and investigation of this feature might provide insight into
the treatment of diabetic ketoacidosis. The parallels to the metabolic syndrome are likely
reflected to varying degrees in other marine mammals, most of which evolved on diets
high in lipid and protein content but essentially devoid of carbohydrate. Utilization of these
natural models of insulin resistance may further our understanding of the pathophysiology
of the metabolic syndrome in humans and better assist the development of preventative
measures and therapies.
Published by Frontiers and copyright of Houser, Champagne and Crocker 2013. The definitive version of this article is available at: http://journal.frontiersin.org/Journal/10.3389/fendo.2013.00164/abstract
2013-11-01T00:00:00ZEffects of Age, Adipose Percent, and Reproduction on PCB Concentrations and Profiles in an Extreme Fasting North Pacific Marine MammalPeterson, Sarah H.Hassrick, Jason L.Lafontaine, AnneThome, Jean-PierreCrocker, Daniel E.Debier, CathyCosta, Daniel P.http://hdl.handle.net/10211.3/1232052014-10-02T09:21:30Z2014-04-01T00:00:00ZEffects of Age, Adipose Percent, and Reproduction on PCB Concentrations and Profiles in an Extreme Fasting North Pacific Marine Mammal
Peterson, Sarah H.; Hassrick, Jason L.; Lafontaine, Anne; Thome, Jean-Pierre; Crocker, Daniel E.; Debier, Cathy; Costa, Daniel P.
Persistent organic pollutants, including polychlorinated biphenyls (PCBs), are widely distributed and detectable far from
anthropogenic sources. Northern elephant seals (Mirounga angustirostris) biannually travel thousands of kilometers to
forage in coastal and open-ocean regions of the northeast Pacific Ocean and then return to land where they fast while
breeding and molting. Our study examined potential effects of age, adipose percent, and the difference between the
breeding and molting fasts on PCB concentrations and congener profiles in blubber and serum of northern elephant seal
females. Between 2005 and 2007, we sampled blubber and blood from 58 seals before and after a foraging trip, which were
then analyzed for PCBs. Age did not significantly affect total PCB concentrations; however, the proportion of PCB congeners
with different numbers of chlorine atoms was significantly affected by age, especially in the outer blubber. Younger adult
females had a significantly greater proportion of low-chlorinated PCBs (tri-, tetra-, and penta-CBs) than older females, with
the opposite trend observed for hepta-CBs, indicating that an age-associated process such as parity (birth) may significantly
affect congener profiles. The percent of adipose tissue had a significant relationship with inner blubber PCB concentrations,
with the highest mean concentrations observed at the end of the molting fast. These results highlight the importance of
sampling across the entire blubber layer when assessing contaminant levels in phocid seals and taking into account the
adipose stores and reproductive status of an animal when conducting contaminant research
Published by PLoS ONE and copyright of Peterson et al. The definitive version of this article is available at: http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0096191
2014-04-01T00:00:00ZHigh Rates of Energy Expenditure and Water Flux in Free-Ranging Point Reyes Mountain Beavers Aplodontia rufa phaeaCrocker, Daniel E.Kofahl, NathanFellers, Gary D.Gates, Natalie B.Houser, Dorian S.http://hdl.handle.net/10211.3/1231642014-10-02T09:19:28Z2007-01-01T00:00:00ZHigh Rates of Energy Expenditure and Water Flux in Free-Ranging Point Reyes Mountain Beavers Aplodontia rufa phaea
Crocker, Daniel E.; Kofahl, Nathan; Fellers, Gary D.; Gates, Natalie B.; Houser, Dorian S.
We measured water flux and energy expenditure in free-ranging
Point Reyes mountain beavers Aplodontia rufa phaea by using
the doubly labeled water method. Previous laboratory investigations
have suggested weak urinary concentrating ability,
high rates of water flux, and low basal metabolic rates in this
species. However, free-ranging measurements from hygric
mammals are rare, and it is not known how these features
interact in the environment. Rates of water flux (210+/-32 mL
d-1) and field metabolic rates (1,488+/-486 kJ d-1) were 159%
and 265%, respectively, of values predicted by allometric equations
for similar-sized herbivores. Mountain beavers can likely
meet their water needs through metabolic water production
and preformed water in food and thus remain in water balance
without access to free water. Arginine-vasopressin levels were
strongly correlated with rates of water flux and plasma
urea : creatinine ratios, suggesting an important role for this
hormone in regulating urinary water loss in mountain beavers.
High field metabolic rates may result from cool burrow temperatures
that are well below lower critical temperatures measured
in previous laboratory studies and suggest that thermoregulation
costs may strongly influence field energetics and
water flux in semifossorial mammals.
Published by and copyright of the University of Chicago Press. The definitive version of this article is available at: http://www.jstor.org/stable/10.1086/521204
2007-01-01T00:00:00Z