Environmental predictors of bottlenose dolphin distribution and core feeding densities in Galveston Bay, Texas /

Bibliographic Details
Main Author: Moreno, Maria Paula Teixeira, 1966-
Other Authors: Würsig, Bernd G. (Thesis advisor)
Format: Thesis eBook
Language:English
Published: [College Station, Tex.] : [Texas A&M University], [2006]
Subjects:
Online Access:Link to OAK Trust copy

MARC

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100 1 |a Moreno, Maria Paula Teixeira,  |d 1966- 
245 1 0 |a Environmental predictors of bottlenose dolphin distribution and core feeding densities in Galveston Bay, Texas /  |c by Maria Paula Teixeira Moreno. 
264 1 |a [College Station, Tex.] :  |b [Texas A&M University],  |c [2006] 
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500 |a "Major Subject: Wildlife and Fisheries Sciences" 
500 |a Title from author supplied metadata (automated record created on Sep. 15, 2006.) 
500 |a Vita. 
500 |a Abstract. 
502 |b Ph. D.  |c Texas A&M University  |d 2005. 
504 |a Includes bibliographical references. 
516 |a Text (Dissertation). 
520 3 |a Coastal dolphins are often exposed to habitat degradation and direct interactions with humans. Major factors that influence dolphin distribution, critical for conservation concerns, are still poorly understood even for the bottlenose dolphin, the best-studied cetacean. To establish the environmental conditions that best predict occurrence of bottlenose dolphins and high feeding densities in Galveston Bay, I conducted a total of 367 boat surveys in five locations of the estuary, totaling 3,814.77 km of search effort. I counted groups of dolphins and measured surface water temperature, salinity, turbidity, total number of boats, shrimp vessels, and number of seabirds. Using geospatial tools, these data -- along with location, distance to the Gulf of Mexico and water depth -- were analyzed on a 500- m resolution grid. Temporal factors at daily and seasonal scales were also examined. Occurrence was modeled using a Generalized Additive Model and core feeding densities (i.e., feeding densities above 2 SD of the mean) were modeled with a Generalized Linear Model. A total of 1,802 dolphins in 262 groups were detected,56.87% of which were feeding. I found that all factors except warm/cold seasons and turbidity were useful to predict dolphin distribution, which was related non-linearly tomost predictors. Fewer variables were relevant in predicting core feeding densities. These were, in decreasing order of relevance, distance to the Gulf of Mexico, surface water temperature, depth, number of boats, and warm/cold seasons. Feeding was highly clustered and the main core areas, less than approximately 3 km² wide, were stable across time of day and season. The majority of the occurrences (86.2%) and feeding groups (94%) were situated in two bay locations - Galveston Ship Channel (GSC) and Bolivar Roads (BRD) - that amounted to only one- fifth of the surveyed area. Compared to conditions in GSC and BRD when no dolphins were sighted, feeding cores were deeper and more seabirds were observed. This fine-scale study of bottlenose dolphin distribution may contribute to a better understanding of habitat requirements for coastal dolphins. It also may provide information needed to minimize potential negative impacts to this population caused by human activities. 
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500 |a Electronic resource. 
650 4 |a Major wildlife and fisheries sciences. 
653 |a GAM 
653 |a habitat 
653 |a environmental predictors 
653 |a bottlenose dolphin 
653 |a feeding 
653 |a GLM 
700 1 |a Würsig, Bernd G.,  |e thesis advisor. 
856 4 0 |u http://hdl.handle.net/1969.1/3803  |z Link to OAK Trust copy  |t 0 
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998 f f |a 2005 Dissertation M67  |t 0  |l Available Online