M.Sc. / Please refer to full text to view abstract

This study focuses on the taxonomy, biogeography and biological aspects of the fishes of Tristan da Cunha and Gough Island in the cental South Atlantic Ocean. Oceanographic measurements were undertaken to determine the position and nature of the Subtropical Convergence (STC) in the vicinity of the islands. The Tristan da Cunha group is thought to be situated on the northern edge of the STC while Gough Island is situated on the southern edge of the front. The seasonal environmental cycle at the islands is characterised by an annual sea surface temperature fluctuation of approximately 5 °C and an annual change in stratification of the water column. It is suggested that this increase in stratification at the STC, brought about in the summer by insolation warming the surface layers of the ocean, enhances primary production. The STC is identified as a unique habitat for fishes and as an important barrier to dispersal of species in the Southern Ocean. The present study has produced 18 new distributional records from the shelf waters of Tristan da Cunha and Gough Island. The fish fauna known from the shelf waters of these islands is reviewed, and a diagnosis, synonymy, and in some cases an illustration are provided. For certain species, brief notes on their biology, relative abundance and seasonal distribution are included. An analysis of the ichthyofaunal relationships between shallow water areas in the vicinity of the STC has resulted in the identification of a characteristic neritic STC ichthyofauna. The circumglobal distribution of many of these species is thought to be a consequence of a dispersive pelagic phase in their life-cycles. Biological processes in fishes at these islands are temporally and spatially affected by seasonal changes in oceanographic conditions. Seasonal sea temperature variation was identified as being an indicator of other oceanographic phenomena that may affect processes such as growth, reproduction and feeding in fishes at the islands. Most species have a summer spawning season and growth rate increased during the summer months. It was hypothesised that enhanced primary production and a related increase in food quality and availability during the summer were the major factors temporally regulating the growth and reproduction of fishes at the islands. Twenty families of neritic fishes have been recorded in the shelf waters of Tristan da Cunha and Gough Island. Most families are represented by only one species. Because of this a wide range of life-history strategies are apparent in the fauna. Nevertheless, there are a number of common life-history characteristics shared by most of the neritic species. Firstly, the early lifehistory of many species included an extended pelagic phase which might have facilitated colonisation throughout the STC zone in the past, thereby regulating extant species diversity in this region. Secondly, the common occurrence of an extended summer breeding season and iteroparity suggested that these characters also contributed to survival in what is considered to be an unpredictable environment. It would appear that these common characteristics hold the key to the success of many fishes in the STC zone. This study has contributed to our understanding of oceanic island ecosystems and has revealed distributional patterns of fishes that were unknown previously. By focusing on the biological processes of selected species the regulatory role played by local environmental conditions became apparent. The results of this study are also relevant to proposed conservation measures for Tristan da Cunha and Gough Island.

The three components of the aerobic respiratory metabolism of sablefish, digestion (SDA), activity, and standard metabolism, were examined separately and together as dependent variables responding to the independent variable, feeding frequency. All fish were similar in size and held within a temperature range of 8.5 - 9.5 C on a 12 hr photoperiod. Fish were studied in both 4000 L mass respirometers equipped with activity meters and in a tunnel respirometer. Identical meals were given every 4, 7, and 14 days. A fourth series of starved fish served as controls. In the mass respirometers, oxygen consumption, ammonia nitrogen excretion, and activity were monitored continuously before, during, and after acclimation to the different feeding frequencies. This permitted estimation of total metabolism, the activity and feeding components of total metabolism, standard metabolism, and protein and lipid catabolism. In the tunnel respirometer, energy expenditures at similar levels of Imposed activity were compared before and after eating to examine repartitioning of locomotor and feeding metabolism. It was found that swimming energy expenditures and standard metabolism are a sigmoid functions of ration frequency. The lowest metabolic rates are associated with the least frequent feedings and the greatest with the most frequent meals. Consequently, total and routine metabolic rates are also direct functions of ration history. The lowest metabolic rates are based on lipid oxidation as an energy source. The fish primarily oxidize proteins to meet metabolic needs when on higher rations. It is also shown that apparent specific dynamic action (SDA) results to a greater extent from catabolic rather than anabolic processes. When the dual metabolic load of locomotion and digestion threatens to exceed the aerobic metabolic scope of the fish, a physiological mechanism exists whereby oxygen supply is preferentially shunted to locomotor requirements. When spontaneously active in the mass respirometers, the activity component of metabolism is generally less than 25% of the standard metabolic rate and digestion and locomotion can proceed synchronously. When swimming spontaneously, the sablefish move at a single, probably optimal velocity regardless of ration history. The better fed fish in the experiments were active most of the day despite the low contribution of the activity component to the routine metabolic rate. These results have significance regarding assumptions often made in bioenergetic models, specifically that activity energy expenditures and standard metabolic rates are independent of ration. They reveal an adaptable physiology which applies different energy partitioning strategies to meet the changing metabolic needs of fish in a dynamic environment with a variable food supply. / Science, Faculty of / Zoology, Department of / Graduate

No description available.

My research has focused on the identification, assemblage dynamics, and horizontal distribution patterns of larval fishes around rocky reefs in the Gulf of California, Mexico. In Chapter One, I analyze a series of light-trap collections taken over 35 nights at San Carlos, Sonora. Nearly 14,000 larvae from 19 families were collected. The five most abundant families contributed 90% of the larvae and the top ten families contributed 99%. Larvae of non-pelagic spawners (gobiids, labrisomids, tripterygiids, chaenopsids, pomacentrids, and bythitids) dominated the collections. Larval catches ranged from 7.5 to 2330.3 larvae/45 min, but changes in catch rate were not related to changes in ambient moonlight. In contrast, the volume of zooplankton collected was correlated with moonlight intensity. Dynamics of the ten dominant fish families were highly variable, but in most cases a large proportion of the larvae were caught on just a few nights. Taxonomic and size selectivities were apparently less severe in my study than in previous Australian studies, and the use of light-traps should be explored further. In Chapter Two, I outline the prediction that larvae of small, non-pelagic spawning fishes should more frequently be retained over reefs during development than fishes with other combinations of body size and egg type, and I describe my research testing this prediction. I made about 160 collections of fish larvae with a light-trap and plankton net at 1, 20, and 100 m from rocky shorelines. These collections yielded 27,265 larvae from about 50 families. Based on larval size frequencies, near-reef concentration gradients, and abundances offshore, I identified four families that can complete development over the reef but also have larvae dispersed offshore (Clupeidae, Engraulididae, Gerreidae, and Haemulidae). In addition, I identified seven families that primarily develop over reefs and have few or no larvae dispersed offshore (Tripterygiidae, Chaenopsidae, some Labrisomidae, Dactyloscopidae, some Gobiidae, Gobiesocidae, and Bythitidae). Adults of these seven families are mostly small, non-pelagic spawners. Larvae from four taxa of larger non-pelagic spawners (Ophioblennius, Labrisomus, Balistes, and Pomacentridae) did not appear to develop over reefs. These findings are in accord with the prediction I made. Chapter Three is a preliminary guide to identification of Gulf of California blennioid larvae. Although blennioid larvae are poorly known and few species have been described, they are well represented (ca. 20,000 larvae from five families) in my collections taken near reefs in the Gulf. Illustrations of 20 species, and brief descriptions of key characters for these and several additional species, are provided. More detailed taxonomic studies on Gulf blenniid, dactyloscopid, tripterygiid, labrisomid, and chaenopsid larvae are in progress.

No description available.

The Deepwater Horizon oil spill in 2010 prompted an enormous survey effort to assess the under-studied, deep-ocean ecosystems of the Gulf of Mexico. The resulting samples and datasets afforded a unique opportunity to study the ecology of a poorly known group of mesopelagic fishes, the barracudinas (Aulopiformes: Paralepididae). Here we address several important data gaps regarding the ecology of the Paralepididae. Our results indicate that a majority of barracudina species are efficient at avoiding research-sized nets, suggesting that their overall abundance has been historically underestimated. Notable differences in vertical distribution, seasonal abundances of sizes classes, and diets were observed among the three major sub-groups of the family, with potential implications to ecosystem-based management of deep-pelagic fisheries. This thesis is dedicated to all the fish, squids, and shrimps that gave their lives to make these data and to those that endured the hardship of the Deepwater Horizon oil spill. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2018. / FAU Electronic Theses and Dissertations Collection

by Chow Cheuk Yi. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1989. / Bibliography: leaves 179-192.

No description available.

Thesis (Ph. D.)--Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution, 1983. / Includes bibliographical references (p. 252-270).