1 / 13

Theoretical Framework

Predation on polychaets and crustaceans through ontogeny in a small bentonic shark ( Mustelus schmitti ). Theoretical Framework. Size of sharks depend on sex and ontogenic stage. Body Length ( Lt ) can affect search and manipulation time of preys.

gavivi
Download Presentation

Theoretical Framework

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Predation on polychaets and crustaceans through ontogeny in a small bentonic shark (Mustelus schmitti)

  2. Theoretical Framework • Size of sharks depend on sex and ontogenic stage. • Body Length (Lt) can affect search and manipulation time of preys. • Changes in diet and resource partitioning minimize intraspecific competion.

  3. Hypothesis & predictions • Change of size implies different quantities and species of preys eaten. • The higher the body length, the less polychaets consumed. • Crustaceans are preyed as size and ontogeny advances. Polychaets < Crustaceans < Fishes F P C

  4. Objectives • Study the effect of the ontogeny on feeding in small bentonic sharks. • Describe the relationship between quantities of polychaets and crustaceans eaten and the lenght, according to stages and sex of Mustelus schmitti.

  5. Experimental design /methods # of preys eaten Ontogeny Two habitats: • Coastal • Depth Body length Immature, Maturing, Mature, Pregnant

  6. Quantities of prey eaten Observed distribution Glm, neg binomial distribution Glm, poisson distribution mle2, neg binom. quadratic mle2 exponential function mle2, neg binom. Holling ,III, IV GAM (crustaceans) mle2, neg binom Ricker mle2, poisson Zero inflated

  7. Model selection Polychaets

  8. Contrasts between sexes within stages

  9. Model selection Crustaceans

  10. GAM model fitted to crustaceans preyed

  11. Quadratic model for crustaceans preyed

  12. Conclusions • Body length had a signifficant effect on the number of prey consumed of each class. • Female sharks eat signifficantly less polychaets than males. • Crustaceans become more important in diet at intermediate body sizes. • Decrease of consumption of crustaceans suggests the intake of a bigger and more active prey (fishes?).

More Related