TRIP TO CEDO - INTRODUCTION TO ECOSYSTEMS
CEDO is the Centro Intercultural de Estudios de Desertos y Oceanos, A. C.
or the Intercultural Center for the study of Deserts and Oceans Inc.
Peggy J. Turk Boyer and Richard E. Boyer, Co-directors
Check out their web site
ITINERARY
It is also a great place for you to see a major sedimentary basin and modern analogs of what you will see in the fossil record on next weeks field trip to Northern Arizona. |
Tuesday, June 9
Drive to CEDO, leaving at 9:00 AM
Swimming in PM possible
CEDO is located just outside Puerto Penasco, Sonora, Mexico on the northern shore of the Gulf of California. The Gulf is one of the most unusual biological and geological environments in the world because, and an ideal place to introduce you to the ecosystem concept and ecosystem evolution. |
Wednesday, June 10
STOP 1 - The Estero Morua, leaving at 7:00 AM
low tide 9:40 AM
Things to bring:Swim wear, notebook, pencil.
Questions to answer
The Estero Morua is a lagoon cut off, except for channel, from the Gulf by huge sand dunes, and it is where you will be introduced to the marine ecosystem the way it is today. Because it has no freshwater stream entering it, the water becomes more salty by evaporation the further up the estero you go. Near its mouth, there are large mud flats inhabited by a shrimp of the genus Callianassa which makes its living basically by eating mud. The significance to the marine ecosystem of this kind of behavior is remarkable.
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Here students from last year are doing the "shrimp dance" in which they liquefy the mud on which they stand, sink deeply into it and, in the process, force the Callianassa (ghost shrimp) to rise to the surface you can get a look at them. In the background you can see some of the sand dunes,
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 Here is a Callianassa (Callianassa truncata) from Italy.
Our species is Callianassa californiensis, which looks
virtually the same. Only males have claws so
unequal in size.
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 The tiny Callianassa makes burrows that can extend for more that a meter below the surface.
On the left is an example of a burrow system filled with epoxy and then excavated. This example is also from Italy, but the estero examples are very similar. By constructing and living in these burrows and eating the organic matter in the sediment the ghost shrimp massively ventilate the sediments, which would otherwise be anoxic.
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The Estero Morua is home to several oyster farms. Last year the students enjoyed several dozen Oysters fresh from the estero, some trying them for the very first time. They were DELICIOUS! But, remember, oysters are detritus feeders and since they are what they eat, they are always an assault on your immune systems. Thus, there is always a slight risk of, well, a reaction.
At the Estero Morua, we will also be examining the normal marine fauna and flora attached to and under beachrock, and we will have our first detailed look at eolian dunes.
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A HREF="ecoevol_cedo.html">Lecture 1 - Evolution of Ecosystems Beginning about 1:30 PM.
STOP 2 - Salina on east side of Puerto Penasco, leaving at 3:30 PM.
Things to bring:Long pants, notebook, pencil, maybe insect repellent.
Questions to answer
A salina is a land-locked lagoon that receives seepage of ocean water through the sand surrounding it. This particular salina obtains its water from seepage from marine water from an experimental shrimp farm. The remarkable thing about salinas is that they frequently have what are called algal or bacteria mats that are essentially holdovers of ecosystems from at least 1.5 billion years ago.
About 900 million years ago, the first macroscopic animals evolved, called the Ediacaran assemblage. and colonized the mats. However, almost none of these animals could burrow into the mud. This all changed about 540 million years ago at the beginning of the Cambrian period. Apparently, all major phyla of animals appear at this time and many enter the mud for protection and for food. This not only aerated the mud, but also wiped out the mat communities, except in places like salinas where they still survive because of the exclusion of nearly all macroscopic animals. This so called "agronomic revolution" (Sielacher, 1997), changed marine ecosystems fundamentally.
Thursday, June 11Lecture 2 - Ecological Transect at Station Beach 9:00 AM.
Things to bring:Swim wear, notebook, pencil.
Questions to answer
STOP 1 - Station Beach, leaving at 9:30 AM
low tide 10:20 AM
Station beach is a rocky beach composed of layers of beachrock dated (by Carbon 14) as greater than 37,000 years old. On, in, and under the beachrock you will find an amazing diversity of animals and photosynthesizing protists (seaweeds). We will examine a transect across this "rocky intertidal" community and attempt a crude census. This is part of a sub-tropical marine ecosystem and it is an antithesis of the salina we will have seen the day before. Although the salinity here is slightly higher than normal, it is still well within the range that marine organisms are comfortable.
On the right are a few of the mollusks you will probably see (from Parker, 1964). But you will see many more organisms which are brightly colored and oddly shaped - and alive. |
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Workshop - Work on data from transect at Station Beach. 1:00 - 3:00 PM. Data collected on the transect will be collated and at the end presented to the class by each transect group.
Lecture 2 - Gulf of California as a Sedimentary Basin. Beginning about 3:00 PM.
Lecture 3 - Desert Ecology (Paul Barber). Beginning about 4:00 PM.
Things to bring:Notebook, pencil.
Questions to answer
Above is an aerial photograph of the area we will be visiting. Puerto Penasco is to the south of this image.
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Stop 4 - Gran Desierto. Leave CEDO at 5:00 PM. Perhaps the most spectacular part of the Sonoran Desert is the Gran Desierto just south of the giant Pinacate Volcano.
The Pinacate Volcano stands over 1200 m tall, is active, and has erupted within the last 60 years. We will walk over one some of its more recent flows.
On the south side of the volcano are parts of the largest sand sea in the new world - the dunes of the Gran Desierto. In the eastern area, where we will visit, the dunes reach heights of from 20 to 80 m.
There can be wonderful displays of animals which come out as the sun sets and the desert cools, which is why we visit the area in the early evening.
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