Nutritional ecology of Agalma okeni and other siphonophores from the epipelagic western North Atlantic Ocean

Submitted in partial fullfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution May 1976The feeding and fishing behavior of siphonophores in their natural environment: was observed by SCUBA diving at 171 stations in warm-water areas of the Western North Atlantic Ocean. Calycophorae and Physonectae showed a two-phase cycle of fishing and swimming. The fishing posture of a siphonophore is determined by its floatation and by the contractility of its stem; fishing postures can be similar in siphonophores which are unrelated generically. Total tentacle length in colonies with 2 - 3 mg body protein can extend 4.5 meters. Variations in the morphology of tentilla reflect differences in the kinds of prey which can be captured. Dissection of feeding polyps revealed that most siphonophores could eat copepods, amphipods, polyc:haetes, pteropods, heteropods, veliger larvae, sergestids, mysids, euphausiids, and small fish, though laboratory experiments showed that not all could eat nauplii. Species which could capture Artemia nauplii usually required 2 - 4 hours to digest them, while large prey took 7 - 18 hours to be digested. Since a single feeding polyp of species which captured nauplii could ingest more than one per minute, colonies with 20 - 150 feeding polyps may be able to eat several hundred individuals within minutes if they encounter aggregations of small zooplankton. Agalma okeni was the most common siphonophore encountered by divers. Colonies of A. okeni maintained in the laboratory on a diet of Artemia nauplii, copepods, or shrimp budded an additional feeding polyp and 1 - 2 pairs of nectophores about every two days. Energetic calculations suggest that small and medium-size colonies incorporate 48% and 33%, respectively, of ingestion into production. A small colony of A. okeni with six nectophores probably requires 2.8 - 5.0 calories to balance daily rates of oxygen consumption and growth; a medium-size colony with 14 nectophores probably requires 5.8 - 9.2 calories. Extrapolating from short-term increases in size in the laboratory, the generation time of A. okeni in tropical and subtropical regions is likely 2 1/2 - 4 weeks. Respiration of siphonophores at 26 ± 3°C ranged from 2 - 86 μ1 02/mg protein-hr, and ammonia excretion ranged from 0.1 - 3.3 μg NH4/mg protein-hr. The cystonects Rhizophysa filiformis and Bathyphysa sibogae had low rates of respiration and excretion, while calycophores of the genus Sulculeolaria had the highest rates. For most siphonophores, ratios of oxygen consumed to ammonia-nitrogen excreted ranged from 16 - 36 and suggest that both protein and lipid are important metabolites.Supported by predoctoral fellowships from the National Science Foundation and the Hoods Hole Oceanographic Institution, and in part by NSF Grants GA-39976 and GA-21715

Distribution and Abundance of Phytoplankton, Zooplankton, Ichthyoplankton, and Micronekton in the Deepwater Gulf of Mexico

Expeditions in the 1960s and 1970s are the basis for the general paradigm that standing stocks and productivity of phytoplankton are both low ( \u3c0.1 mg chl·m-3; \u3c150 mg C.m-2·d-1) seaward of the shelf-slope break in the Gulf of Mexico. The present review supports this description of the mean (stable) state but also shows hot spots in primary production (\u3e2 g C·m-2·d-1) occur when/where nutrient availability is locally enhanced seaward of the shelf-slope break. Recent collections with Bongo and MOCNESS nets, midwater trawls, and bioacoustic surveys of the Loop Current and associated cyclonic and anticyclonic eddies in the Gulf of Mexico show that these deepwater hot spots have higher stocks of zooplankton and micronekton as well. The local aggregations ranged in size from coarse- to meso- spatial scales (10s to 100s of kilometers) though locations of such oases were spatially variable along the continental margin

Ship and Satellite Studies of Mesoscale Circulation and Sperm Whale Habitats in the Northeast Gulf of Mexico During GulfCet II

Eighty-three encounters with sperm whales (Physeter macrocephalus) occurred on two cruises that made expendable bathythermograph + conductivity-temperature-depth surveys of cyclone-anticyclone eddy pairs in the Northeast Gulf of Mexico (NEGOM). In late summer 1996, 41 sightings of sperm whales were made and 10 acoustic contacts were registered. Of these 51 encounters, 90% were in a cyclonic area of lower than average dynamic height offshore that was surveyed from space by near-real-time altimetric sea surface height anomaly and then mapped in high resolution with shipboard measurements or within 100 km of SW Pass of the Mississippi River. In midsummer 1997, 23 sightings and nine acoustic contacts were made. Of these 32 encounters, 81% were in an offshore cyclonic area of lower than average dynamic height or within 100 km of the mouth of the Mississippi River. Time series animation of the 1996 and 1997 altimetric data indicated these cyclones are typically associated with Loop Current excursions into the NEGOM and that the two cyclones we surveyed had spun up 4-6 mo previous to our fieldwork. Although cyclones in the NEGOM are temporally persistent, their geographic location is spatially variable: the cyclone surveyed in 1996 was centered 150-200 km south and east of the Mississippi River delta in water 2-3 km deep, whereas that surveyed in 1997 was centered farther east in water 2-3 km deep over DeSoto Canyon. Sperm whales appear to have affinity for cyclonic eddies because the largest numbers of encounters with sperm whales also shifted east in 1997 compared with 1996

A new VLA/e-MERLIN limit on central images in the gravitational lens system CLASS B1030+074

We present new VLA 22-GHz and e-MERLIN 5-GHz observations of CLASS B1030+074, a two-image strong gravitational lens system whose background source is a compact flat-spectrum radio quasar. In such systems we expect a third image of the background source to form close to the centre of the lensing galaxy. The existence and brightness of such images is important for investigation of the central mass distributions of lensing galaxies, but only one secure detection has been made so far in a galaxy-scale lens system. The noise levels achieved in our new B1030+074 images reach 3 microJy/beam and represent an improvement in central image constraints of nearly an order of magnitude over previous work, with correspondingly better resulting limits on the shape of the central mass profile of the lensing galaxy. Simple models with an isothermal outer power law slope now require either the influence of a central supermassive black hole, or an inner power law slope very close to isothermal, in order to suppress the central image below our detection limit. Using the central mass profiles inferred from light distributions in Virgo galaxies, moved to z=0.5, and matching to the observed Einstein radius, we now find that 45% of such mass profiles should give observable central images, 10% should give central images with a flux density still below our limit, and the remaining systems have extreme demagnification produced by the central SMBH. Further observations of similar objects will therefore allow proper statistical constraints to be placed on the central properties of elliptical galaxies at high redshift.Comment: Accepted by Monthly Notices of the Royal Astronomical Society. 16 pages, 8 figure

Summertime Nutrient Supply to Near-Surface Waters of the Northeastern Gulf of Mexico: 1998, 1999, and 2000

In the summers of 1998, 1999, and 2000, deep water eddies induced strong anticyclonic currents along the upper slope and outer shelf from the Mississippi River delta to the west Florida shelf. Those currents transported Mississippi River discharge eastward along the outer shelf and slope, reversing the normal offshore increase in salinity, with the exception of a few regions very near the coast that were influenced by the discharges from other rivers or bays. The entrainment of low-salinity river water resulted in anomalously high chlorophyll a concentrations in the upper 15 m over the outer shelf and upper slope, in contrast to the concentrations that typically occur over deep water in the subtropics in summer. Nitrate concentrations in this surface water were quite low except near the mouths of rivers, which act as point sources for nutrients; presumably, this was because of the rapid utilization of nitrate by phytoplankton. A significant supply of nutrients to the euphotic zone at regions quite removed from these point sources resulted from eddies intruding onto or formed over the slope. These caused mid-depth water rich in nutrients to be uplifted to within the euphotic zone, the uplift depending on the location and intensity of the eddies. Based on measurements at approximately 100 stations on each cruise, estimates were made of the quantity of nitrate and silicate in the upper 15 m of the water column and in the depth interval from 15m to 60 m, the nominal depth of the euphotic zone. Study results suggest that the nitrate and silicate in the near-surface interval of 0-15 m largely resulted from riverine discharge and subsequent advection, while the nutrients between 15 and 60 m resulted from uplift of waters by circulation features. The euphotic zone occupied at least the upper 60 m of the water column, but standing stocks of nitrate and silicate in the 15- to 60-m layer were between two and six times those in the upper 15 m on all three cruises and appeared to depend on the strength and relative proximity to the shelf break of local anticyclonic features. The effects of these circulation features were potentially significant in supplying nutrients to the euphotic zone during these summers

A “step too far” or “perfect sense”? A qualitative study of British adults’ views on mandating COVID-19 vaccination and vaccine passports

BACKGROUND: Debate is ongoing about mandating COVID-19 vaccination to maximise uptake. Policymakers must consider whether to mandate, for how long, and in which contexts, taking into account not only legal and ethical questions but also public opinion. Implementing mandates among populations who oppose them could be counterproductive. METHODS: Qualitative telephone interviews (Feb-May 2021) with British adults explored views on vaccine passports and mandatory vaccination. Participants (n=50) were purposively selected from respondents to a probability-based national survey of attitudes to COVID-19 vaccination, to include those expressing vaccine-hesitancy. Data were analysed thematically. FINDINGS: Six themes were identified in participants’ narratives concerning mandates: (i) mandates are a necessary and proportionate response for some occupations to protect the vulnerable and facilitate the resumption of free movement; (ii) mandates undermine autonomy and choice; (iii) mandates represent an over-reach of state power; (iv) mandates could potentially create ‘vaccine apartheid’; (v) the importance of context and framing; and (vi) mandates present considerable feasibility challenges. Those refusing vaccination tended to argue strongly against mandates. However, those in favour of vaccination also expressed concerns about freedom of choice, state coercion and social divisiveness. DISCUSSION: To our knowledge, this is the first in-depth UK study of public views on COVID-19 vaccine mandates. It does not assess support for different mandates but explores emotions, principles and reasoning underpinning views. Our data suggest that debate around mandates can arouse strong concerns and could entrench scepticism. Policymakers should proceed with caution. While surveys can provide snapshots of opinion on mandates, views are complex and further consultation is needed regarding specific scenarios

Arts practice and research: locating alterity and expertise.

This is the peer reviewed version of the following article: Grennan, S. (2015). Arts Practice and Research: Locating Alterity and Expertise. International Journal of Art & Design Education, 34(2), 249-259. doi: 10.1111/jade.1776 , which has been published in final form athttp://onlinelibrary.wiley.com/doi/10.1111/jade.1776/epdf. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-ArchivingThere is still no agreed pedagogic definition of practice-based research. However, there is not a dearth of definitions, but rather a wide variety, predicated upon the developing programmes of individual places of study. This article will examine these definitions in terms of underlying concepts of intentionality and alterity and the ways in which instrumental use of them affects study. The article will discuss a number of existing models for the theorising and adjudication of practice as research, and the questions that underpin their development. First, are non-text outputs, and the methods of their production, able to communicate knowledge rather than simply constituting knowledge? Second, by what criteria can this knowledge be adjudicated within an academic environment? Third, what is the status of these outputs and methods relative to the production of text? It will propose that interrogation of these models will advance little in discussions that focus on media. Text or nottext is beside the point. Rather, the relationship between research and practice can be explored as a relationship between intentionality and alterity, based in an essentially social conception of communities of expertise, including academic communities of expertise. Finally, the article will describe an attempt by the author to undertake a drawing activity in response to a research question, in order to assess the possibilities of articulating practice specifically in order to demonstrate expert knowledge of the field in which a research question occurs

Grouping practices in the primary school: what influences change?

During the 1990s, there was considerable emphasis on promoting particular kinds of pupil grouping as a means of raising educational standards. This survey of 2000 primary schools explored the extent to which schools had changed their grouping practices in responses to this, the nature of the changes made and the reasons for those changes. Forty eight percent of responding schools reported that they had made no change. Twenty two percent reported changes because of the literacy hour, 2% because of the numeracy hour, 7% because of a combination of these and 21% for other reasons. Important influences on decisions about the types of grouping adopted were related to pupil learning and differentiation, teaching, the implementation of the national literacy strategy, practical issues and school self-evaluation