Offshore Migratory Corridors and Aerial Photogrammetric Body Length Comparisons of Southbound Gray Whales, Eschrichtius robustus, in the Southern California Bight, 1988–1990

Through most of their annual migration, gray whales, Eschrichtius robustus, remain within 10 km of shore, but in the Southern California Bight many individuals migrate much farther from shore. This paper summarizes aerial survey and photogrammetric efforts to determine body lengths and temporal and spatial distributions of migratory gray whales in the southern portion of the Southern California Bight. Aerial surveys were flown along 13 east–west transects between lat. 32°35′N and 33°30′N during the southbound gray whale migratory seasons of 1988–90 in the Southern California Bight. Photogrammetry was used to obtain body length estimates of animals during some of the surveys. A total of 1,878 whales in 675 groups were sighted along 25,440 km of transect distance flown and 217 body lengths were measured. Using position and heading data, three major migratory pathways or corridors in the southern portion of the bight are defined. Those migrating offshore were split almost evenly between two corridors along the west sides of Santa Catalina and San Clemente Islands. These corridors converge on the mainland coast between San Diego and the United States–Mexico border. No whales larger than 11.5 m were photographed within 30 km of the mainland coast, suggesting that smaller, and presumably younger, whales use the coastal migratory corridor through the California Bight

Elites and modernity in Mozambique

This thesis examines the connections between ideologies of modernity and social power for three interrelated sets of elites in Mozambique. My research is based on 20 months of ethnographic fieldwork primarily, but not solely, among the now adult children of high-ranking members of Frelimo (Mozambican Liberation Front, the ruling party since independence) and those closely associated with the party in the capital city of Maputo. It examines how elites’ transforming relationship to the project of modernity has allowed them to survive periods of dramatic social change while maintaining power, although in a modified form. The thesis argues that “local” understandings of modernity held by dominant groups in Mozambique have created the wider political field that unifies elites and creates the parameters in which they operate. It allows them both to control the positions that underwrite their social power and to attempt to justify their positions of power. The thesis examines the source of elites’ social dominance and how it has been transformed over the generations. I also investigate how recent social, political and economic changes have created a growing backlash among social groups who were once Frelimo’s strongest supporters. The thesis argues that through the acquisition and monopolisation of “modern” skills, such as high levels of education, elites can survive contested legitimacy because there are few who seem capable of replacing them

Growth of a sea urchin, Allocentrotus fragilis, at different depths off the Oregon coast

Allocentrotus fragilis (Jackson) was obtained from six stations at depths of 100 to 1260 m on the continental shelf and upper slope off Newport, Oregon. Ages and growth rates of A. fragilis were determined by two methods: 1) A procedure was developed to make growth zones of the skeletal test plates visible. Alternating light and dark growth zones were found to be formed semi-annually. The total number of growth zones was used to indicate the urchin's age. 2) Age and growth rate values were also determined from analyses of size-frequency distributions of trawl collections from 200 m. Collections from other depths were not adequate for size-frequency analyses. Gonad indices of A. fragilis from 200 m were used to determine spawning periodicity and frequency. A semi-annual frequency was found, with spawning occurring in early spring and early autumn. No A. fragilis specimens collected below 400 m were reproductively mature. The growth curve of A. fragilis from 200 m, which was plotted from the mean test diameter of age groups defined by test plate growth zones, shows a good least-squares fit with von Bertalanffy's growth equation. Growth rates were similar for A. fragilis from 100-600 m, but decreased for specimens from 800 and 1260 m. The maximum test diameter decreased with increasing depth below 200 m. Variation of magnesium content of the calcareous skeletal plates was due largely to variation with age. Little skeletal Mg variation was found at different depths for specimens of the same age. Greater Mg content differences occurred between young and old specimens from the same depth, and between young and old test plates of the same individual. The effects of several environmental factors on the growth rate and maximum size of A. fragi1is are discussed. Of these factors, food availability, water temperature, and oxygen tension form gradients with depth or distance offshore; and were considered to be important in affecting the growth of A. fragilis

Growth in marine mammals : a review of growth patterns, composition and energy investment

Funded under award from Office of Naval Research: N000142012392. DPC and SA were funded under the E&P Sound and Marine Life Joint Industry Programme of the International Association of Oil and Gas Producers (IOGP; grant 00-07-23). CRM is supported by the Australian Integrated Marine Observing System (IMOS), IMOS s enabled by the National Collaborative Research Infrastructure Strategy.Growth of structural mass and energy reserves influences individual survival, reproductive success, population and species life history. Metrics of structural growth and energy storage of individuals are often used to assess population health and reproductive potential, which can inform conservation. However, the energetic costs of tissue deposition for structural growth and energy stores and their prioritization within bioenergetic budgets are poorly documented. This is particularly true across marine mammal species as resources are accumulated at sea, limiting the ability to measure energy allocation and prioritization. We reviewed the literature on marine mammal growth to summarize growth patterns, explore their tissue compositions, assess the energetic costs of depositing these tissues and explore the tradeoffs associated with growth. Generally, marine mammals exhibit logarithmic growth. This means that the energetic costs related to growth and tissue deposition are high for early postnatal animals, but small compared to the total energy budget as animals get older. Growth patterns can also change in response to resource availability, habitat and other energy demands, such that they can serve as an indicator of individual and population health. Composition of tissues remained consistent with respect to protein and water content across species; however, there was a high degree of variability in the lipid content of both muscle (0.1–74.3%) and blubber (0.4–97.9%) due to the use of lipids as energy storage. We found that relatively few well-studied species dominate the literature, leaving data gaps for entire taxa, such as beaked whales. The purpose of this review was to identify such gaps, to inform future research priorities and to improve our understanding of how marine mammals grow and the associated energetic costs.Publisher PDFPeer reviewe

Intra‐ and inter‐annual variation in gray whale body condition on a foraging ground

Baleen whales store energy gained on foraging grounds to support reproduction and other metabolic needs while fasting for long periods during migration. Whale body condition can be used to monitor foraging success, and thus better understand and anticipate individual‐ and population‐level trends in reproduction and survival. We assessed the body condition of eastern North Pacific gray whales (Eschrichtius robustus) on their foraging grounds along the Oregon coast, USA, from June to October of three consecutive years (2016–2018). We used drone photogrammetry and applied the body area index (BAI) to measure and compare whale body condition, which is a continuous, unitless metric similar to the body mass index in humans. A total of 289 drone flights were carried out over 106 photo‐identified whales, which were grouped into demographic units by sex, maturity, and female reproductive status. Calves and pregnant females displayed the highest BAIs, followed by resting females, mature males, and, finally, lactating females, reflecting the significant energetic demands on reproductive females. In all three years, gray whale body condition improved with the progression of feeding seasons, demonstrating the accumulation of body energy reserves on the foraging grounds. Yet, body condition was significantly better in 2016 than in 2017 and 2018 when overall body depletion was observed, indicating a difference in prey availability and/or quality between years. We analyzed local upwelling patterns between 2013 and 2018 as an oceanographic proxy for prey and determined significantly greater upwelling between 2013 and 2015 than low upwelling years between 2016 and 2018. We hypothesize that these upwelling patterns created ecosystem shifts in primary productivity and zooplankton prey of gray whales, causing carry‐over effects between foraging success and body condition in subsequent years. This study demonstrates the value of monitoring whale body condition to better understand temporal variation in foraging success, and potentially detect and describe the causes of anomalous changes in whale population health, such as the 2019 gray whale mortality event

Abnormal P300 in people with high risk of developing psychosis

Background Individuals with an “at-risk mental state” (or “prodromal” symptoms) have a 20–40% chance of developing psychosis; however it is difficult to predict which of them will become ill on the basis of their clinical symptoms alone. We examined whether neurophysiological markers could help to identify those who are particularly vulnerable. Method 35 cases meeting PACE criteria for the at-risk mental state (ARMS) and 57 controls performed an auditory oddball task whilst their electroencephalogram was recorded. The latency and amplitude of the P300 and N100 waves were compared between groups using linear regression. Results The P300 amplitude was significantly reduced in the ARMS group [8.6 ± 6.4 microvolt] compared to controls [12.7 ± 5.8 microvolt] (p < 0.01). There were no group differences in P300 latency or in the amplitude and latency of the N100. Of the at-risk subjects that were followed up, seven (21%) developed psychosis. Conclusion Reduction in the amplitude of the P300 is associated with an increased vulnerability to psychosis. Neurophysiological and other biological markers may be of use to predict clinical outcomes in populations at high risk

Delta-9-tetrahydrocannabinol, neural oscillations above 20 Hz and induced acute psychosis

Rationale: An acute challenge with delta-9-tetrahydrocannabinol (THC) can induce psychotic symptoms including delusions. High electroencephalography (EEG) frequencies, above 20 Hz, have previously been implicated in psychosis and schizophrenia. Objectives: The objective of this study is to determine the effect of intravenous THC compared to placebo on high-frequency EEG. Methods: A double-blind cross-over study design was used. In the resting state, the high-beta to low-gamma magnitude (21–45 Hz) was investigated (n=13 pairs+4 THC only). Also, the event-related synchronisation (ERS) of motor-associated high gamma was studied using a self-paced button press task (n=15). Results: In the resting state, there was a significant condition × frequency interaction (p=0.00017), consisting of a shift towards higher frequencies under THC conditions (reduced high beta [21–27 Hz] and increased low gamma [27–45 Hz]). There was also a condition × frequency × location interaction (p=0.006), such that the reduction in 21–27-Hz magnitude tended to be more prominent in anterior regions, whilst posterior areas tended to show greater 27–45-Hz increases. This effect was correlated with positive symptoms, as assessed on the Positive and Negative Syndrome Scale (PANSS) (r=0.429, p=0.042). In the motor task, there was a main effect of THC to increase 65–130-Hz ERS (p=0.035) over contra-lateral sensorimotor areas, which was driven by increased magnitude in the higher, 85–130-Hz band (p=0.02) and not the 65–85-Hz band. Conclusions: The THC-induced shift to faster gamma oscillations may represent an over-activation of the cortex, possibly related to saliency misattribution in the delusional state

Growth of a Sea Urchin, Allocentrotus fragilis, off the Oregon Coast

Allocentrotus fragilis (Jackson) was obtained from six stations at depths of 100 to 1,260 m on the continental shelf and upper slope off Newport, Oregon. Ages and growth rates of A. fragilis were determined by two methods: (1) from size-frequency distributions of trawl collections from 200 m, and (2) from growth zones on skeletal test plates. Collections from other depths were not adequate for size-frequency analyses. Gonad indices of A. fragilis from 200 m were used to determine spawning periodicity and frequency. A semiannual frequency was suggested, with spawning occurring in early spring and early autumn. No individuals collected below 400 m were reproductively mature. A procedure was developed to make growth zones of the skeletal test plates visible. Dark growth zones are thought to correspond to semiannual periods of growth, one-half the number of dark growth zones indicating the urchin's age. The growth curve of A. fragilis from 200 m, which was plotted from the mean test diameter of age groups defined by test plate growth zones, shows a good least-squares fit to von Bertalanffy's growth equation. Growth rates determined from plate growth zones appeared to be similar for A.fragilis from 100 to 600 m, but decreased for specimens from 800 to 1,260 m. The asymptotic size decreased with increasing depth below 200 m

An Introduction to the Biology of Marine Life

X, 434 tr.; 25 cm

An introduction to the biology of marine life

484 tr., X; 25 cm