Relationship Between Amounts of Zooxanthellae
Intertidal Zone Distribution in Anthopleura
xanthogrammica
Bi 3B [Bio 3B]
Patricia Seabourne
[Professor Steve Teh]
and
Introduction
Zooxanthellae are photosynthetic algae that inhabit the endodermal tissues of their
hosts (Weiss 10996). Anthopleura xanthogrammica is common in the lower and middle
intertidal zones in the west coast of North America, and it forms symbiotic relationships
with photosynthetic algae.
The color of the algae makes the anemone brownish
grenn[brownish-green]. Anemones with Zooxanthellae can be found throughout the
intertidal zone, but favor the upper levels (Bates 2000; second et al. 2000). Bates
explains that high-shore individuals of A. xanthogrammica tend to have predominantly
Zooxanthellae and are brownish-green in color. Zooxanthellae favours higher
temperatures and higher light conditions[more exposure to light]. In order to determine
the relationships between amounts of Zooxanthellae present and intertidal zone
distribution, I developed the hypothesis that A. xanthogrammica living in the middle
intertidal zone, contain higher amounts of Zooxanthellae.
Methods
Six tentacles were collected at Aliso Creek Beach, Laguna Beach, California, and
six tentacles were collected at Woods Cove, Palos Verdes, California. I wane[went] to
Aliso Creek Beach during the lowest tide (Lowest tide=1.2[units?]) and started collecting
tentacles at the lowest point of the intertidal zone. I walked toward the bottom of the
lower zone, found an animal. And cut a tentacle[, and cut a tentacle off it]. . [random
period]Then, I continued walking until I found another animal and I cut another tentacle.
It was difficult to cut tentacles from anemones that were contracted, thus I avoided those.
I also avoided anemones I found in crevices, and under rocks. I continued walking the
lower intertidal zone until I collected six tentacles from six different A. xanthogrammica.
Then, I moved to the middle zone and I began collecting six tentacles in the same manner.
Collection at the Palos Verdes location was carried in the same way with a low tide of 0.6[units?]. I placed the samples in plastic containers and immediately froze them. Tips
of A. xanthogrammica were used for analysis. All tentacles were cut into the same
volune[weight] (0.2 grams), placed in an Eppendorf tube and dipped in a 15 ul of distilled
water. The tentacles mixture was homogenized using a glass rod, and the density was
calculated. The mixture was placed in an hemacytometer under a light microscope. The
number of Zooxanthellae was counted in eight squares. Then, the cell concentration was
calculated by dividing the average cells in the eight squares by the volume of a square.
The final Zooxanthellae volume was calculated by dividing the obtained density
musltiplied by the initial value by the recommended cell density.[multiplying the
obtained density by the initial value and then dividing this by the recommended cell
density.]
Results
Anemones with a higher concentration of Zooxanthellae were observed in the
higher intertidal zone, or middle zone, while the anemones with the lower concentration
of Zooxanthellae were observed in the lower intertidal zone.
[these figures are illegible... something must have happened when transferring them from
excel... in excel, just select the graph, press ctrl+c, then click where you want the graph in
your paper, and press ctrl+v]
Figure 1. Amount of Zooxanthellae in Lower Intertidal Zone and Middle Intertidal
Zone.[need some numbers/data relevant to graphs... also there are 2 graphs labeled as
Figure 1.. you need to separate them into Figure 1 and Figure 2]
Correlation between amount of Zooxanthellae and tidal zone distribution was clear. The
mean amount of Zooxanthellae present in anemones from the middle intertidal zone was
higher. (Figure 1).
Discussion
The location in the intertidal zone seems to affect the number of Zooxanthellae
present in the anemone; the anemones with a higher number of Zooxanthellae seem to
prefer locations in the middle intertidal zone, and the anemones with lower numbers of
Zooxanthellae are more likely to be found in the lower intertidal zone. As Bates (2000)
mentioned, anemones with Zooxanthellae are usually found in the higher intertidal zones.
Higher numbers of Zooxanthellae found in anemones further from the water ay[may]
help anemones survive better[more harsh conditions]. Also, anemones can always find a
crevice or shaded area where to hide. These shaded microhabitats may help the
Zooxanthellae survive. While collecting specimens of A. xanthogrammica, I only chose
specimens exposed to the sun and light, thus my results indicate the amounts of
Zooxanthellae found in anemones which are exposed. If tentacles were collected from
anemones found in shaded areas, the results may differ[duplicate information]. The
amount of Zooxanthellae seems to be directly correlated to the amount of Zooxanthellae
present in the anemone. Figure 1 suggests that the standard deviation and mean standard
error is also lower for anemones found in the middle intertidal zone. Figure 1 also
indicates that middle zone anemones have the higher mean. This result supports my
hypothesis that anemones with higher concentrations of Zooxanthellae are more likely to
be found in higher intertidal zones. Even thought[though] my results support my
hypothesis, some points should be mentioned[reworded, sounds weird]. All the results are
based in samples collected from anemones exposed to sunlight. If the tentacles would
have been collected from specimens living in shaded areas or crevices, the results might
have been different[duplicate information]. Also, counting Zooxanthellae cells using an
hemacytometer needs to be done very precisely. Counting errors can alter the results
significantly. There is still a lot to learn[like what? Give examples] about the relationship
between tidal zone distribution and amounts of Zooxanthellae.