Invasive Species

  • Lionfish are invasive from Indian Ocean, reproduce rapidly, voracious opportunistic eaters, no natural predators

Invasive Marine Species

  • Problem: native species are at risk due to displacement by, competition with, and predation by invasive species

  • Conservation Challenges: Invasives often go undetected for a long period of time or or damaging impacts are not immediately obvious (crypticity)

    • What else?

      • kudzu

      • Japanese stiltgrass

      • Lespedeza

      • Elaeagnus

The Misawa Dock

Invasive Marine Species: Dispersal Methods

  • Aquarium trade

    • pet store animals released into world

  • Aquaculture

    • storm disrupts aquaculture facilities, disturbing them, escape into world

  • Canal construction

    • Panama Canal connects Atlantic to Pacific, and ocean creatures cling onto ships passing through it

  • Shipping

    • Galapagos has many rare species, would be devastated if invasive brought in through ships

  • Live seafood trade

Invasives and Fisheries

  • Sea Walnut (Mnemiopsis leidyi) or comb jelly

    • Voracious predator of zooplankton and pelagic fish eggs attributed to fisheries collapse

    • moves with sea current

    • moved from Atlantic ocean, decimated fisheries

  • Lionfish (Pterois volitans)

    • Indo-Pacific invasive species

    • lives up to 30year

    • consumes 20 fish in 30 minutes

    • spawn 30-40k eggs every 3-5 days

Invasives and Climate Change

  • Sargassum (seaweed) assaults coast

    • drives away tourists

    • destroys wildlife habitat

    • sea turtle babies live in sargassum, which is removed, harmful to them

    • has balloon-like structures that help it float in the sea

    • hard for sea turtles to make nests

Invasives and Aquaculture

  • cultivated red seaweeds: Eucheuma denticulatum, Kappaphycus alvarezii, Gracilaria salicornia, Hypnea musciformis

So how can we think about such trends in ecological terms?

  • outcompete native species

  • exceeds carrying capacity of environment

  • predation of natives

Underlying Ecological Processes

  • Predation

    • carrying capacity is often a stabilizing effect between predators and prey

    • “co-existence at stable equilibra”

  • competition

    • niche partitioning (specific roles, habitats, food, that are taken)

Predation: Lotka-Volterra Model

  • important factors

    • how much prey is available?

    • how efficient are predators at capturing (effect of single predator on the per capita growth rate of prey)

    • specificity of predator

Competition: Exclusion or Coexistence

  • Now two species can occur in the same niche in the same habitat at the same time

  • If two species are after same resource, one has better adaptations or eats more, the second will fall in population.

  • Dominance and Exclusion

  • Invasive species have dominance

Scale

  • How would you summarize the scale/scope of the invasive species issue?

    • global, can happen anywhere

    • snowball effect on native species and habitat