Discussion

The results of this study seem to be consistent with past research completed on the distribution of these organisms through out the inter-tidal (Knox 2001). Ascophyllum and its associated epifauna are important to the cycling of nutrients in the inter-tidal. By looking at the micro community present on Ascophyllum we can understand the process of nutrient flows from primary producers to filter feeds, etc… up through the trophic levels.

One of the most fascinating observations I made during this study was the use of Ascopyllum nodosum pnuematocysts by L. obtusada and Mytilis. I am most interested in the presence of L. obtusada because they are the only known grazer that is not deterred by the noxious compound excreted by Ascophyllum. I am not certain if L. obtusada are born inside the pnuematocyst or migrate there at a young age, but in either case the pnuematocysts appears to be a preferred habitat of juvenile L. obtusada snails. This observation has raised a number of questions about the relationship between Ascophyllum and L. Obtusada i. How do the snails find the injured pnuematocysts? ii. Do snails that inhabit pnuematocysts experience higher fitness than those who are not? iii. What enables L. obtusada to consume Ascophyllum and the noxious chemicals. ? iv. When does L. obtusada acquire a liking for Ascophyllum? Are they born immune to the chemicals? v. Does the birth environment of L. obtusada affect their ability to consume Ascophyllum?

Further research into the association between these two partners may lead to some interesting conclusions about the origin and mechanisms of this relationship. The presence of L. obtusada may benefit Ascophyllum by excreting feces rich in Ammonium (Taylor & Rees 1998). Nitrogen is often a limiting factor in the growth of seaweeds, so increasing the supply of available nitrogen, in the form of Ammonium, it is likely to positively affect the growth of Ascophyllum (Taylor & Rees 1998).

The presence of L. obtusada may affect the attachment rates of P. lanosa by creating damaged sites with greater access to tissue below the epidermis layer that is sloughed off periodically by asscophyllum to protect against epiphytes. The settlement of P. lanosa is initially established using adhesive vesicles (Chemberlain & Evans; Pearson & Evans 1990). It can take up to two months before the epiphyte is able to penetrate the epidermis with unicellular rhizoids (Pearson & Evans 1990).

Although the importance of the Ascophyllum – P. lanosa association is not fully understood, there is some evidence that nutrient exchange occurs between the two algae. P. lanosa is partially dependent on the transfer of amino acids, phosphates, and other minerals from Ascophyllum (. There also appears to be a reciprocal exchange of photosynthetically fixed carbon compounds (Ciciotte & Thomas 1997).