A study was done on a rocky intertidal community in Puerto Penasco, Sonora, Mexico in the summers of 1997--1999 in order to determine if the ENSO of 1997--1998 had an effect on population densities of selected macroinvertebrates. Two replicate transects were laid perpendicular to the sea edge and a census of 21 macroinvertebrate species was taken in the summers of 1997, 1998 and 1999. A significant decrease of species densities occurred in 1998 when the mean sea surface temperature (SST) was more than 2°C warmer than in 1997 due to the 1997--1998 ENSO event. A phenomenon was also observed in 1998 where some species changed, compared to 1997, their vertical distribution in the intertidal from shallow to deeper waters, with a subsequent return to a more expected distribution in 1999. Also a comparison of 1997 and 1976 densities showed an increase in 1997 in abundances of those species with southern geographic ranges and a decrease of those with northern geographic ranges. This was correlated with an increase of mean SST of 1.9°C between the 1970's and the 1990's.
| Identifer | oai:union.ndltd.org:arizona.edu/oai:arizona.openrepository.com:10150/278712 |
| Date | January 1999 |
| Creators | Chandler, Margaret Ann |
| Contributors | Thomson, Donald A. |
| Publisher | The University of Arizona. |
| Source Sets | University of Arizona |
| Language | en_US |
| Detected Language | English |
| Type | text, Thesis-Reproduction (electronic) |
| Rights | Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author. |
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