Impacts of invasive species: from species to ecosystems. Aschwin Engelen
Centro de Ciências do Mar do Algarve
General introduction invasions • 3 big global human impacts on nature: – global climate change
General introduction invasions • 3 big global human impacts on nature: – global climate change – habitat destruction and fragmentation
General introduction invasions • 3 big global human impacts on nature: – global climate change – habitat destruction and fragmentation – biological invasions –
In 2002, the European Council (Environment) noted that the introduction of IAS is one of the main recorded causes of biodiversity loss and causes serious damage to economy and health.
Biological invasions • What are invasive species? • Under the Convention on Biological Diversity (CBD), invasive alien species (IAS) are those that are introduced, establish, naturalize, and spread outside of their home range, and whose impacts involve significant harm.
• Currently 97 registrated in Portugal (ISSG database)
Biological marine invasions • Causes: – disruption of natural barriers • large water masses: oceans, seas – ship hull and ballast water
• cultivation of exotic species
• Impacts – economical: uncertain for most marine invasions – ecological: ranging from single species replacement to entire ecosystems
• Costs? – There are only two estimates of the total cost of invasive species at the national level, both relating to the United States. • 1993: 79 species over 85 yrs 97 billion dollars • 2000: annual costs 137 billion dollars
Seaweed Invasion impacts on Humans •Physical hindrance of small boats with outboard engines of up to 20 h.p. •Clogging of intake pipes, both of boats and industrial installations •Floating mats foul commercial fishing lines and nets •Floating debris tends to be concentrated by buoyant fronds forming floating mats and creating an eyesore •Large mats of weeds are eventually cast up on shores and cause problems when rotting, i.e. producing offensive smells on resort beaches •Dense growths of S. muticum on oyster beds: difficult to see cultured oysters relocation of oysters •Loss in amenity and recreational use of water areas, e.g. swimming, skiing, sail boarding, dinghy sailing and fishing
Ecological invasion impacts
Healthy, dense seagrass bed
Mat forming seaweeds
Canopy forming seaweeds
Ecosystem level
Community level
Macrophyte interactions
Environmental factors
Light
Nutrients
Sulfide
Temp
Ecological invasion impacts
Healthy, dense seagrass bed
Mat forming seaweeds
Canopy forming seaweeds
Ecosystem level
Community level
Macrophyte interactions
Density threshold
Environmental factors
Light
Nutrients
Sulfide
Effect of macrophyte on abiotic factors
Abiotic factor
+ Synergistic effects
Temp Seaweed density/biomass
Ecological invasion impacts
Healthy, dense seagrass bed
Mat forming seaweeds
Canopy forming seaweeds
Ecosystem level
Associated community composition
Community level
Density threshold
Macrophyte interactions
Density threshold
Environmental factors
Light
Nutrients
Sulfide
Effect of macrophyte on abiotic factors
Abiotic factor
+ Synergistic effects
Temp Seaweed density/biomass
Ecological invasion impacts
Healthy, dense seagrass bed
Mat forming seaweeds
Canopy forming seaweeds
X X
System metabolism Foodweb structure Macrophyte decomposition
X Ecosystem level X
X
X
P7
Associated community composition
Community level
Density threshold
Macrophyte interactions
Density threshold
Environmental factors
Light
Nutrients
Sulfide
Effect of macrophyte on abiotic factors
Abiotic factor
+ Synergistic effects
Temp Seaweed density/biomass
Impacts of invasive species •Large global problem, goes hand in hand with globelization •Large impact economically and ecologically •Characteristics of the invader and the recipient system determines impact
