[MARMAM] Odontocete community change and its relationships with enviromental variability

christian salvadeo chsalvadeo at yahoo.com.mx
Fri Jun 27 11:49:29 PDT 2008


Hello to all:
I have just finished my Masters degree, and the Spanish version of my thesis is available 
The name of the thesis is: 
ODONTOCETE COMMUNITY CHANGE AND ITS RELATIONSHIPS WITH ENVIROMENTAL VARIABILITY IN THE SOUTH-WEST GULF OF CALIFORNIA, MEXICO
ABSTRACT
Community structure is a function of the number of species, their relative abundances and the characteristics of the dominant, common and rare species that are part of it; also, it can be forced by natural fluctuations in their environment. The study area presents a strong seasonal variability due to the Gulf of California ocean dynamics. In addition, the abundance of the most sighted odontocetes species changes temporally. We suggest that the community changes are consequence of environmental variations mediated by prey availability. To verify this hypothesis, we compared odontocetes community changes in the South-West Gulf of California with environmental data, such as sea surface temperature and Chla pigment concentration estimated from satellite images, ocean depth obtained from a bathymetric model and food availability (sardines and squid) gathered from published reports. Odontocetes community information was obtained from 21 sampling trips from
 September-2003 to March-2006 with an effort of 7325.5 km. We recorded the presence, location and other biological parameters of odontocetes sightings. Our results show a temporal lag between the peak of productivity and the major odontocetes relative abundance. Additionally, we observed a seasonal dynamic in the community structure and habitat use. During the warm and less productive season, the community shows a preference for neritic areas with productive waters, whit a dominance of squid-eating species (mostly pilot whales and an oceanic group of bottlenose dolphins). Along the temperate and highly productive season the fish-eating species dominate (particularly common dolphins) with no preference for thermal front. Furthermore, squid-eating species preferred oceanic waters. This seasonal dynamic of the community is in agreement to prey availability in the study area. This may occur as a consequence of the prey migrating pattern driven by
 environmental variability of the gulf waters.
If someone need more information about the thesis or the pdf, please send me an e- mail to chsalvadeo at yahoo.com.mx
Saludos
Christian Salvadeo
CICIMAR-IPN
La Paz, B.C.S., México

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