Katie Brown
Biology 130
Abalone Size Frequency in the Intertidal
Summary of method
We will be working to uncover the total abundance and average size of the black abalone that still remain on the Santa Cruz Island. This field survey will require the use of calipers to measure the size of these beautiful sea snails. We will be surveying dead as well as living black abalone in order to compare the difference in sizes. Also, looking at the dead abalone versus the living will give us insight into how drastic the withering foot syndrome disease has effected the black abalone of the intertidal. This pathogen shrinks the foot of the black abalone so that the mollusk cannot attach to rock, leading to high mortality rates. Withering foot syndrome is a wasting disease that has been evident since the major drops in black abalone population in the Channel Islands in the 1980s and has been rampant on our California coast ever since. In order to efficiently measure the size of these organisms we will be working in buddy pairs using a call-out system; one person will be using a caliper to measure the longest point of the shell and will call out the size in centimeters. The partner recording the information will then call back the size they heard so that there is no discrepancy in communication. This call back system is crucial for accurate data.
Purpose of method
We will be exploring the intertidal zone off the coast of the Santa Cruz Islands in order to determine the overall frequency and size of black abalone that are living and attached to hard substrate, as well as deceased. We will be able to compare growth rates between the living and dead black abalone, giving us a greater understanding of the impacts of withering foot syndrome.
Benefits and limitations of the technique
Measuring the size and estimating total abundance will help to observe how resilient these organisms are to this debilitating disease and how beneficial it is to live in a protected area away from human impacts. This survey will compare growth rates of the living and dead, which is also an important part of the organism’s evolution over the last 30 years. The major benefit of this method is being able to look at black abalone growth rates by looking at organism’s age in correlation with their size. Limitations of the technique will be determined by high or low tides and wave shock on the small area we will be surveying.
Considerations required
When touching these organisms, we must remember that they are hemophiliacs. This means that if they are punctured or obtain an open sore they will not be able to clot their blood properly and will bleed out. We must also consider the tragic effects the withering foot syndrome has had on the organisms population overtime, and be aware that the black abalone still left are extremely persistent. If the tide is high and wave action is rough we may have to estimate the size and frequency of these organisms because this hub requires students to be standing on mostly rock that is not submerged.
Utility of this technique for other ecosystems
The use of calipers is fundamental to all ecosystems because it measures the size of growing organisms overtime, as well as how the expense of their growth when they are dead. This shows us how long the life span of an organism is relative to size and allows us to compare the dead organisms and resilient living population of black abalone considering the effects of withering foot syndrome.
List of Equipment Needed
* Calipers
* Field Notebook