Research & Experiments
Alyssa Demko has been working to answer a question.
"How is palatability of seaweeds influenced by latitude of the seaweeds and phylogeny of the seaweeds?"
The goal is to have an idea as to which kinds of seaweeds are more appealing to eat and why. Having a pleasant or agreeable taste is called palatability. Alyssa will be looking to see if certain traits link to palatability. Alyssa has been working with 50 seaweeds (31 Rhodophyta or red algae and 19 Phaeophyta or brown algae) found in different regions or latitudes (polar, temperate, tropical) and comparing how herbivores eat foreign seaweeds versus local seaweed found here in our marsh.
Alyssa's Hypothesis: Palatability of seaweed will increase with latitude.
Two scientific techniques Alyssa has been using to test her hypothesis are:
Click the following links below to explore more about these techniques!
"How is palatability of seaweeds influenced by latitude of the seaweeds and phylogeny of the seaweeds?"
The goal is to have an idea as to which kinds of seaweeds are more appealing to eat and why. Having a pleasant or agreeable taste is called palatability. Alyssa will be looking to see if certain traits link to palatability. Alyssa has been working with 50 seaweeds (31 Rhodophyta or red algae and 19 Phaeophyta or brown algae) found in different regions or latitudes (polar, temperate, tropical) and comparing how herbivores eat foreign seaweeds versus local seaweed found here in our marsh.
Alyssa's Hypothesis: Palatability of seaweed will increase with latitude.
Two scientific techniques Alyssa has been using to test her hypothesis are:
- Feeding assays
- DNA trait analysis with PCR
Click the following links below to explore more about these techniques!
Results/Conclusions:
Alyssa determined that seaweeds from polar and temperate locations were twice as
palatable as were seaweeds from the tropical location. This latitudinal
increase in palatability is largely explained by how urchins reacted to Rhodophytes (red seaweeds) in the feeding assays. Urchins showed that they loved polar red seaweeds versus tropical red seaweeds. The palatability of Phaeophytes (brown seaweeds) did not significantly differ across latitudes (polar, temperate, tropical).
Chemistry also played a role in the latitudinal increase in palatability. Latitudinal increases in nutritional content were measured by percent carbon, nitrogen, and ash-free dry mass. For example, polar seaweeds are much more rich in nitrogen, which is very appealing to herbivores. So overall if given the option, herbivores will choose polar seaweeds versus the tropical ones.
Protein content was also analyzed, but there were no significant relationships between latitudinal origin or palatability.
In conclusion, tropical red seaweeds were significantly less palatable than temperate and polar reds than was expected. This suggests that tropical red seaweeds have undescribed chemical defenses that make them take less appealing to generalist herbivores.
Chemistry also played a role in the latitudinal increase in palatability. Latitudinal increases in nutritional content were measured by percent carbon, nitrogen, and ash-free dry mass. For example, polar seaweeds are much more rich in nitrogen, which is very appealing to herbivores. So overall if given the option, herbivores will choose polar seaweeds versus the tropical ones.
Protein content was also analyzed, but there were no significant relationships between latitudinal origin or palatability.
In conclusion, tropical red seaweeds were significantly less palatable than temperate and polar reds than was expected. This suggests that tropical red seaweeds have undescribed chemical defenses that make them take less appealing to generalist herbivores.
Updates:
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Alyssa completed her MS thesis defense on Latitudinal gradients in seaweed nutritional content and palatability to generalist marine herbivores. She now moves onto Paul Jensen’s laboratory at Scripps Institute of Oceanography to pursue a PhD in microbial ecology. More details about her thesis results can be found on Dr. Sotka's page here.
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