Fish Trophic Levels: Symbiosis + Competition

trophic relationships of inner shelf fish

trophic relationships of rocky reef fish

association vs effect (table)

problem with fish competition

difficult to observe with the exception of territoriality (ex: sarcastic fringehead, garibaldi, black perch)

inter-phylum competition

black perch + urchins compete for food (kelp), eventually perch has to leave

the ghost of competition past

what you see is a result of something that’s already happened. fish don’t perform these behaviors often, especially in front of an observer

realized niche

Coextensive niche model

where each species can use the same range of resources in the absence of its competitor, yet each is the dominant competitor at opposite ends of that range. Each species excludes the other from opposite ends of the resource gradient in a fairly symmetrical way.

Niche overlap model with symmetrical competition

both species undergo fairly equal niche shifts

Niche overlap model with asymmetrical competition

the dominant competitor (Dom) undergoes a substantially smaller niche shift than the subordinate competitor (Sub)

Included niche model

a dominant specialist (S) eliminates a subordinate generalist (G) from most of the region of niche overlap, leaving the generalist to survive in a "competitive refuge" (CR)

how to figure out if resource partitioning

eliminate one to see if one moves in or not (black + yellow rockfish vs gopher rockfish)

symbiosis

mutualism, phoresis-non-obligatory, inquilinism/endoecism, parasite picking (+ mimicry), heterospecific shoaling)

mutualism

participants benefit each other thru their direct contact (ex: clownfish + anemone)

phoresis-non-obligatory

a host provides shelter, support, or transport for one or more other species (ex: shark + pilot fish, carangid + jellyfish)

inquilinism (endoecism)

seek shelter in living invertebrates (fish in spiny urchin)

parasite picking + mimicry

ex: blacksmith + senorita, scythe butterflyfish + kelp bass, gulls + sunfish)

sabertooth blenny pretends to be a wrasse and bites fish

heterospecific shoaling

shark gets disguise, bait gets protection (too small for the shark to eat)

cookiecutter shark

thick lips and modified larynx are used to attach to prey and razor sharp teeth are used to bite plug out of prey