The effects of phlorotannin concentrations of brown seaweeds (Phaeophyceae) on the feeding rates of the black sea hare Aplysia vaccaria

Danielle McHaskell Dr. Jayson R Smith College of Biological Sciences California State Polytechnic University, Pomona Importance of Herbivores

• A Type of Predation

• Great diversity with in the Rocky Intertidal Zone

• Herbivores drive population abundance Chemical Defense

Herbivory is a negative impact on the agal individual

Tactics to deter herbivorey

Palatability: how easily the nutrients of a seaweed can be assimilated into the body through digestion

Astringency: A chemical that binds to a protein to produce a precipitate which inhibits assimilation of nutrients.

Astringency Palatability Phlorotannins

Within the class of Phenols Phloroglucinol Polymerization of Phloroglucinol units

Produced in Phaeophyceans (Brown algae)

UV protection Dieckol Anti-microbial

Herbivore deterrence

Located within Physodes

Variation in concentration due to taxa Variation in Phlorotannins Among Phaeophycean Taxa Fucoids Kelps

From Smith et al. 2014 Aplysia vacarria The Black Sea Hare

Phylum: Mollusca, Class: Gastropoda

1 year life span, reaching:

length: 99cm (39 in)

mass: 14kg (31 lbs)

Consume primarily brown algae

Large herbivore may have play an important role in population dynamics

Little work on their diet and no work on the effect of phlorotannin on feeding selectivity Objectives

Feeding Rate Phlorotannin Concentraitontes will decreas Compare the concentration of phlorotannins of native and non-native phaeophycean species in southern California by using the Folin-Ciocalteau Assay. Determine the feeding rate of A. vaccaria when offered different brown seaweeds Determine relationship between feeding rates and phlorotannin concentration Hypothesize that feeding ra e with increasing phlorotannins Samples Collected

Target 8 species of seaweed to compare phlorotannin concentration among taxa Samples collected from various sites along the Pneumatocysts coast of southern California Samples consisted of blades* Conceptacles Colorimetric Assay

Quantification of Phlorotannin Concentration

Determined Phlorotannin percentage for 7 species

Folin -Ciocalteau (FC) Assay

Homogenize algae

Extract Phlorotannins

Add FC reagent

Absorbance recorded

Phloroglucinol used as a standard Feeding Rate Trials

7 individuals of A. vaccaria

Individual tanks

Starved for 48 hours

5 different seaweed species were offered

Consumption rate measured

Change in wet weight over 24 hour feeding trial

Autogenic weight change accounted for. Seaweed Species: Fucoids Silvetia compressa Hesperophycus californica

Colorimetric Assay Sargassum muticum Feeding Sargassum horneri Rate Trial Seaweed Species: Kelps Undaria pinnatifida Egregria menziesii

Macrocystis pyrifera Eisenia arborea Results: Phlorotannins

ANOVA P<0.001 Kelps Fucoids Results: Feeding Rates

ANOVA P<0.001 Results: Relationship

*

*Phlorotannin percentage data retrieved from Steinburg 1985 Conclusions

• Kelps tend to have a lower amount of phlorotannins and Fucoids tend to have a higher amount.

• Eisenia arborea and Sargassum muticum do not fit the trend we predicted.

• There is a slight trend but not significant Future Work Undaria pinnatifida Hesperophycus californicus

Egregria menziesii

Previous work

Future work Future Work

High Phlorotannin Low Phlorotannin Sargassum agardhianum

Native

Non- Native Acknowledgements Mentor: Dr. Jayson Smith Seaweed Collection: Leonard Ko, Maddie Thompson Institution: California State Polytechnic University of Pomona Funding: NIH, COAST Program: MBRS RISE Grant #: 1R25GM113748-01