02 Ecology

02 Ecology - Paradigm Shift Fish Ecology the most fun you...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
Fish Ecology the most fun you can have with fish without eating them Paradigm Shift ± From: “Balance of nature” ± To: “The only constant is change” ± The dynamic nature of fish faunas makes more sense under new paradigm ± Once assumed an underlying predictable structure to which systems would return if perturbed. ± Underlying structure of ecological systems is a moving target. ± Scales of change Local to regional climatically influenced ecological to evolutionary temporal frames ± Humans are major drivers of change Ecological Filters ± Presence of a particular population of fish dependent on historical events & ecological filters ± Pleistocene events --10,000 ybp ± Zoogeographic barriers ± Physiological factors Codfishes: < 2 o C inhibits Cl-secreting mech ± Biological Interactions --species excluded by competitors, predators, parasites or lack of suitable prey Ecological Filters . .. ± Natural disturbances ; natural community ± Human disturbances ; observed community,changed due to extinctions, introductions, fishing pressure, water management,habitat modifications, etc. Fish Community ± An assemblage of fishes structured by species interactions = fish community ± Assemblage = co-occurring populations does not imply significant interactions ± Fundamental niche (abiotic; G. E. Hutchinson) ± Realized niche (~abiotic - biotic) ± Niche = resources (energy, materials, sites) used (Hurlbert 1981 Evol. Theory) ± Two views of structuring forces: deterministic vs stochastic equilibrium vs non-equilibrium ± Fish communities of both kinds have been described Tropical coral reef communities stochastic Temperate rocky intertidal communities deterministic ± Researchers do not always agree on characterizations Fish Community . ..
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Deterministic communities ± Structured by species interactions ± Characteristics: Persistent, year to year Resilient, bounce back after a disaster Little overlap in use of space &/or food Spp show high degree of co-evolved morphological differences ± This characterization questioned in complex communities Stochastic communities ± Environment too variable to allow a predictable community to develop ± Species populations rarely reach densities high enough for competition or biotic interactions to regulate community ± Overlaps in use of space & food are common & many spp are morphologically similar ± Rests in part on Intermediate Disturbance Hypothesis Intermediate Disturbance Hypothesis Disturbance Low High S p e c i s d v r t y Few dominant spp Few good colonizers Intermediate Disturbance Hypothesis ± Diversity highest where disturbance is moderate ± Competing species coexist because environment favors neither for very long ± Only dominant competitors survive in undisturbed habitats ± Only a few very hardy or good colonizers survive in highly disturbed habitats ± Damsel fish-Keystone species Predator-prey Relationships ±
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 7

02 Ecology - Paradigm Shift Fish Ecology the most fun you...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online