PhD Research

The Dynamics of Delayed Development in Kelp Forest Systems

Joint Doctorate of Ecology-University of California, Davis & San Diego State University

Forest-forming kelp species provide essential ecosystem services to the surrounding nearshore marine environment, deep sea and coastal terrestrial communities; their loss causes subsequent species losses throughout these ecosystems. Every 3-5 years, El Nino events bring conditions of low nutrients and severe storms to the Pacific coast of North America, which can devastate kelp forest communities on a regional scale. It has been suggested that the microscopic stages of kelp can survive this devastation, develop into adults after the disturbance, promoting rapid recovery verses awaiting the arrival of new propagules from distant populations. Little is known about which kelp species rely on these stages or the processes that regulate development.

In addition, California kelp populations experience decreased fitness due to high rates of inbreeding (i.e. when propagules released from one plant mate with each other). Inbreeding may be responsible for the large fluctuations in kelp biomass that have been observed over the last 50 years along the Pacific coast of North America (Raimondi et al. 2004). The longer a microscopic stage persists, the greater its chance of encountering an unrelated individual to mate with. Therefore, populations that rely on long-lived microscopic stages may be more stable.

I will investigate the following hypotheses:

1. Changing environmental factors control a delay and resumption of development for annual and perennial kelp species.

2. Delayed gametophytes within a propagule bank decrease the effects of inbreeding by successfully mating with:

i. younger siblings and;
ii. less-related individuals (non-siblings).

3. Removing the seed bank from natural substratum decreases recruitment density and changes kelp species composition and these effects change seasonally and spatially within the kelp forest.

Kelp gametophyte	Microscopic kelp sporophyte	Adult Nereocystis