Bioenergetic and ecological consequences of diet variability in Atlantic croaker Micropogonias undulatus

Atlantic croaker Micropogonias undulatus is a commercially and ecologically important bottom-associated fish that occurs in marine and estuarine systems from Cape Cod, MA to Mexico. I documented the temporal and spatial variability in the diet of Atlantic croaker in Chesapeake Bay and found that in the summer fish, particularly bay anchovies Anchoa mitchilli, make up at least 20% of the diet of croaker by weight. The use of a pelagic food source seems unusual for a bottom-associated fish such as croaker, but appears to be a crepuscular feeding habit that has not been previously detected. Thus, I investigated the bioenergetic consequences of secondary piscivory to the distribution of croaker, to the condition of individuals within the population and to the ecosystem. Generalized additive models revealed that the biomass of anchovy explained some of the variability in croaker occurrence and abundance in Chesapeake Bay. However, physical factors, specifically temperature, salinity, and seasonal dynamics were stronger determinants of croaker distribution than potential prey availability. To better understand the bioenergetic consequences of diet variability at the individual level, I tested the hypothesis that croaker feeding on anchovies would be in better condition than those feeding on polychaetes using a variety of condition measures that operate on multiple time scales, including RNA:DNA, Fulton's condition factor (K), relative weight (Wr), energy density, hepatosomatic index (HSI), and gonadosomatic index (GSI). Of these condition measures, several morphometric measures were significantly positively correlated with each other and with the percentage (by weight) of anchovy in croaker diets, suggesting that the type of prey eaten is important in improving the overall condition of individual croaker. To estimate the bioenergetic consequences of diet variability on growth and consumption in croaker, I developed and validated a bioenergetic model for Atlantic croaker in the laboratory. The application of this model suggested that croaker could be an important competitor with weakfish and striped bass for food resources during the spring and summer when population abundances of these three fishes are high in Chesapeake Bay. Even though anchovies made up a relatively small portion of croaker diet and only at certain times of the year, croaker consumed more anchovy at the population level than striped bass in all simulated years and nearly as much anchovy as weakfish. This indicates that weak trophic interactions between species are important in understanding ecosystem processes and should be considered in ecosystem-based management.

The Oud Across Arabic Culture

This study is a compilation and compendium of information on the oud, the most important instrument in Arabic classical music. It has grown out of my own long-time involvement in studying and playing the oud, and in particular out of my interest in the lack of sources and knowledge available to the vast majority of oud players and researchers, as well as for the readers. My own path started from an intensive study of the oud, which included exposure to several treaties; some housed in museums around the globe, and some only available in the Arabic language. The study combines archival research (including Arabic poetry and pre-Islamic Era and medieval treaties), symbolism, new archaeological discoveries, field interviews, and analysis of existing scholarship, and draws on my professional performance experience for detailed stylistic analysis of the oud's performance practice and its historical development. The study consists of participant observation, personal performance, and interviews conducted in person, via telephone, and/or via e-mail, according to the choice of the performers. The performers have been selected from networks of musicians who perform regularly at lounges, concert halls, and private events. These performers have been chosen according to their musical knowledge, technical skill, experience, and activity in Arabic music and oud performance. Chapter one deals with the purpose of this study and the methods of investigation, as well as giving a brief overview of the history of the oud. In addition, there will be an introduction to the Arabic musical system (mâqâm), which is primarily based on the mechanics and sound production of the oud. Chapter two deals with the oud in Arabic sources: the first source is Arabic poetry in the pre-Islamic Era. The second source is Arabic poetry in the medieval era, in which I found a significant number of poets who allude to the oud, providing accurate descriptions of the player, singers, and the scenes within the contexts of oud performance. The third source is the Arab scholars' intensive treatises with meticulous accounts of the instrument's apparatii, including descriptions and measurements of the parts, strings, and tuning. While chapter three deals with the classification, the development of the oud, chapter four deals with topics such as: the symbolism of the oud and its relation to cosmology, astronomy, mathematics and anatomy. In most of the pertinent Arabic writings, philosophers mention a significant correlation between the oud and the other sciences. Chapter five deals with recreating the performance practice of the oud. A case study of the oud performers focuses on their style, technique, training, and personal experiences. Topics such as improvisation and ornamentation, the oud in the Arabic musical ensemble, the social uses and functions, and gender in musical performance practices will be included in detailed analysis. Other important topics will be analyzed such as traditional vs. modern technique, and the repertoire of the oud. Specifically, in regard to technique, the study outline the style of the music, the role of the oud in Arabic ensembles, the function of the oud in music composition, and the form of the ensembles in Arabic performance and practice.