Shining new light on mammalian diving physiology using wearable near-infrared spectroscopy

Investigation of marine mammal dive-by-dive blood distribution and oxygenation has been limited by a lack of non-invasive technology for use in freely diving animals. Here, we developed a non-invasive near-infrared spectroscopy (NIRS) device to measure relative changes in blood volume and haemoglobin oxygenation continuously in the blubber and brain of voluntarily diving harbour seals. Our results show that seals routinely exhibit preparatory peripheral vasoconstriction accompanied by increased cerebral blood volume approximately 15 s before submersion. These anticipatory adjustments confirm that blood redistribution in seals is under some degree of cognitive control that precedes the mammalian dive response. Seals also routinely increase cerebral oxygenation at a consistent time during each dive, despite a lack of access to ambient air. We suggest that this frequent and reproducible reoxygenation pattern, without access to ambient air, is underpinned by previously unrecognised changes in cerebral drainage. The ability to track blood volume and oxygenation in different tissues using NIRS will facilitate a more accurate understanding of physiological plasticity in diving animals in an increasingly disturbed and exploited environment

The light requirements for growth and photosynthesis in seagrasses with emphasis on Texas estuaries : a literature survey

During the last 20 years, seagrass communities throughout the world have experienced decreased productivity and distribution. These declines have often been attributed to decreased water transparency as a result of turbidity or shading by epiphytic algae. Epiphytic shading is often an indication of nutrient enrichment caused by anthropogenic inputs. Although both epiphytes and turbidity occur as natural phenomena, human activities can exacerbate existing natural conditions with adverse effects on seagrass communities. The objectives of this study were (a) to review the existing literature and data available on the effect of natural and anthropogenic factors on the underwater light environment; (b) to examine the relationship between light and seagrass distribution and productivity; and (c) to make recommendations on how to protect seagrass habitats in Texas bays and estuaries. To meet these goals, we have examined the available literature, emphasizing the physiological response of seagrasses to light and temperature. By using data and observations collected on a variety of species from around the world we may be better able to define the light requirements of Texas seagrasses. A knowledge of the minimum annual light requirements for seagrass growth is necessary to maintain the current distribution of Texas species. This information will also be required in the development of a management plan that permits the expansion and establishment of new seagrass habitat.Submitted to United States Environmental Protection Agency, Region 6 ... Dallas, Tx31 July 1993Marine Scienc

Factors affecting estuarine populations of Nereocystis luetkeana in Kachemak Bay, Alaska

Thesis (M.S.) University of Alaska Fairbanks, 2003Nereocystis luetkeana forms extensive kelp beds in Kachemak Bay, Alaska. Salinity and turbidity gradients apparently regulate kelp bed distribution throughout this estuary. The beds are large at the entrance of the bay, only solitary stands occur in the inner bay, and no kelp is found at the head of the bay. The role of salinity and turbidity on Nereocystis sporophyte growth was investigated by performing reciprocal transplants among three beds along the bay axis and regularly measuring stipe growth. The effects of salinity and light on spores were studied in the laboratory by recording sinking tendency, settlement success, germination success, and germ tube length under different salinity and light levels. Grazing effects of Lacuna vincta impacted the survival of Nereocystis transplants in-situ and on plants of different age classes in the laboratory. Overall, this study suggests a possible negative estuarine effect on sporophytes transplanted from the outer to the inner bay and on certain aspects of spore development. Herbivory pressure had significant localized effects on Nereocystis survival and was most pronounced on juvenile plants. The dynamics of Nereocystis kelp beds in Kachemak Bay results from large-scale environmental factors and local-scale biological processes

Florida marine biotechnology: research, development and training capabilities to advance science and commerce

The level of activity and interest in “marine biotechnology” among Florida university faculty and allied laboratory scientists is reported in this document. The information will be used to (1) promote networking and collaboration in research and education, (2) inform industry of possible academic partners, (3) identify contacts interested in potential new sources of funding, and (4) assist development of funding for a statewide marine biotechnology research, training and development program. This document is the first of its kind. Institutions of higher learning were given the opportunity to contribute both an overview of campus capabilities and individual faculty Expressions of Scientific Interest. They are listed in the table of contents. (104pp.

Aerospace Medicine and Biology: A continuing bibliography with indexes

This bibliography lists 253 reports, articles, and other documents introduced into the NASA scientific and technical information system in October 1975

Aerospace Medicine and Biology: A continuing bibliography with indexes, supplement 145

This bibliography lists 301 reports, articles, and other documents introduced into the NASA scientific and technical information system in August 1975

Role of adenylyl cyclase S674 in central and forearm vasomotor control

This study examined the cardiac and vasomotor responses to submaximal handgrip exercise and beta-adrenergic control in carriers (n = 6) and non-carriers (n = 4) of a genetic variant of adenylyl cyclase 6 (AC S674). Rhythmic handgrip contractions (1 minute bout; 2 second contraction-relaxation period) were performed at three different intensities (20, 40, and 60% of maximal voluntary contraction force) to test the vasodilatory response to exercise. Additionally, two 5 minute infusions of isoproterenol (0.01 and 0.02 µg·kg-1·min-1 diluted in 5% dextrose) and one 10 minute infusion of propranolol (0.1 mg·kg-1 diluted in 0.9% saline) were used to examine beta-adrenergic mediated cardiovascular responses. Ascending aorta and brachial artery mean blood flow velocities (pulsed Doppler ultrasound) and brachial artery blood pressure (Finometer) were continuously measured during handgrip and pharmacological protocols. Vascular mechanics of the forearm were calculated using a three-element lumped windkessel model. At baseline, AC S674 carriers have decreased systemic vascular conductance and forearm vascular bed compliance, as well as increased pulse pressure. However, AC S674 carriers did not exhibit altered cardiac or vasomotor control during handgrip exercise, isoproterenol infusion, or propranolol infusion. These results indicate that expression of the dysfunctional genetic variant AC S674 has profound effects on systemic hemodynamics at rest. Chronic elevation in vascular contractile state may result in vascular stiffening and enhanced pulse pressures with detrimental long-term consequences for cardiovascular health

Plasma nitrite reserve and vascular function before and after handgrip training in patients with heart failure

There is a direct relationship between vascular health and physical function. The controllers of this relationship are unclear, but appear to involve biomechanical and biochemical influences on the vascular wall. Purpose: The purpose of this dissertation was twofold: (1) to explore the relationship between vascular health and physical function in three populations (elderly, young and chronic heart failure patients); and (2) to determine the modifying role of physical activity, inactivity and exercise training on controllers of this relationship. Methods: Four projects were designed to address 3 key issues in exercise vascular biology, including the influence of the pattern of blood flow on the vasculature; the effects of exercise training with blood flow restriction vascular function; and the influence of exercise training on vascular function in individuals with known disease. Results: Projects 1 and 2 indicate an increase in oscillatory shear within the vasculature with aging. This appears to be associated with lower physical function. Those individuals who maintain a higher amount of daily physical activity have more favorable blood flow pattern and higher vascular function. Project 3 indicates that localized exercise training with blood flow restriction dissociates vascular and muscle gains leading to enhanced muscular strength but diminished vascular function. The controller involved in the lower vascular function may be reduced shear stress during exercise. The controller that contributes to greater muscle strength during blood flow restriction remains unknown. Project 4 concludes that localized exercise training significantly improves vascular function and muscular strength in heart failure patients, although the gains are less than in age-matched individuals. The underlying controllers are unclear but may involve localized increases in shear stress and reduced oxidative stress. However, the benefits of exercise training are transient with vascular function returning to pre-training levels within 4 weeks after cessation of the training stimulus. Conclusion: These projects confirm a direct relationship between vascular health and physical function. This relationship is modifiable with physical activity levels and exercise training. It appears that intermittent shear stress, as seen with acute exercise, and oxidative stress serve as important stewards of the relationship between vascular and physical function

Science-based restoration monitoring of coastal habitats, Volume Two: Tools for monitoring coastal habitats

Healthy coastal habitats are not only important ecologically; they also support healthy coastal communities and improve the quality of people’s lives. Despite their many benefits and values, coastal habitats have been systematically modified, degraded, and destroyed throughout the United States and its protectorates beginning with European colonization in the 1600’s (Dahl 1990). As a result, many coastal habitats around the United States are in desperate need of restoration. The monitoring of restoration projects, the focus of this document, is necessary to ensure that restoration efforts are successful, to further the science, and to increase the efficiency of future restoration efforts