Lecture Topic: Lecture Topic: Basic ecological principles of competition and the associated affects on marine community structure

A Biological Community is “all of the populations of organisms living together (and potentially interacting) within the ecosystem.”

Community: Within a community you have interactions among the species themselves that can lead to: Within a community you have interactions among the species themselves that can lead to: (a) Predation (b) Symbiosis (c) COMPETITION

What is competition? “A contest among organisms in the demand for a necessary resource that is in short supply.” “A contest among organisms in the demand for a necessary resource that is in short supply.” a. Interspecific a. Interspecific b. Intraspecific b. Intraspecific c. Predator-Prey c. Predator-Prey d. Within a plant community d. Within a plant community

EXAMPLE #1: Zonation and Interspecific“Competition” in a Barnacle community

“Rocky Intertidal” (LIS)

The 2 barnacles occupy different niches, Upper limits of Balanus set by water, while lower limits of Chthamalus set by Competition. (If you remove Balanus, then Chthamalus will move lower but it typically cannot because it gets out-competed).

EXAMPLE #2: Predator-Prey “Competition” between a mussel and sea star

Pisaster: A “keystone predator” Predator-Prey Dynamics can influence a community, leading to diversity

EXAMPLE #3: ZONATION and “Competition” IN THE (TIDAL WETLAND) PLANT COMMUNITY

High Marsh Low Marsh Shoal/Mud Flat

<-- Iva frutescens (Marsh Elder) <-- Distichlis spicata (Spike Grass) (low vigor) S. alterniflora (IM)

IM cont. Juncus -> Phragmites Again…DIVERSITY!!!

There can even be “zonation” between a plant and animal species.

Species Diversity is EVERYWHERE… Now get out there and see what you can find!