Multiscale analysis of cetacean distribution in the Gulf of Mexico /
The distribution of cetaceans in the northeastern Gulf of Mexico was compared to concurrent shipboard oceanographic measurements, using data collected on seven cruises, from 1996 to 1999. Horizontal spatial scales of environmental variables were also estimated to determine the optimum sample unit f...
| Main Author: | |
|---|---|
| Format: | Thesis Book |
| Language: | English |
| Published: |
[Place of publication not identified] :
[publisher not identified] ;
2002.
|
| Subjects: | |
| Online Access: | http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=726464431&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD |
| Summary: | The distribution of cetaceans in the northeastern Gulf of Mexico was compared to concurrent shipboard oceanographic measurements, using data collected on seven cruises, from 1996 to 1999. Horizontal spatial scales of environmental variables were also estimated to determine the optimum sample unit for analysis. Decorrelation spatial scale lengths ranged from 3.9 km (for depth of the maximum backscatter measured with an acoustic Doppler current profiler) to 39.6 km (for mixed layer depth), with a mean horizontal spatial scale of 13.5 for all environmental variables. Canonical Correspondence Analysis (CCA) was then used to relate the abundance of cetacean species to environmental variables including acoustic backscatter, bathymetric region, depth, depth slope, distance to shore, distance to the continental margin, hydrographic region, sea surface chlorophyll concentration, dynamic height, salinity, and temperature. A multiscale approach was followed by performing CCA on three datasets with survey effort segments of 5, 10, and 20 km. Variation of species abundance data was then partitioned into independent components, to remove the spatial structure of the community and the spatial structure of environmental variables. The amount of cetacean species variation explained by environmental variables differed between bathymetric regions (continental shelf and continental slope) and between the 5, 10, and 20 km survey effort segments. On the continental shelf, the highest amount of variance in species data (24.2%) was explained by sea surface dynamic height anomaly, surface chlorophyll concentration, and surface salinity when 20 km effort segments were used. On the continental slope, the highest amount of variance in the species data (31.6%) was explained by surface salinity, distance to shore, hydrographic region, and skewness of acoustic backscatter when 5 km effort segments were used. In the southern Gulf of Mexico, distribution of cetaceans was analyzed using data collected on six shipboard surveys and from historical records. Out of 28 cetacean species previously registered in the entire Gulf, records of 25 species were found for the southern region. However, more surveys are necessary to determine the distribution and abundance of cetaceans in the southern Gulf of Mexico, particularly in the deep waters beyond the continental shelf. |
|---|---|
| Item Description: | Vita. "Major Subject: Wildlife and Fisheries Sciences". |
| Physical Description: | xvi, 170 leaves : illustrations, maps ; 28 cm. Issued also on microfiche from University Microfilm Inc. |
| Bibliography: | Includes bibliographical references (leaves 124-143). |