Impact on native communities
- Start date: Month 1
- Responsible partner: Universidad
de Oviedo
- Partners involved: Universidad
de Oviedo, Universidade
do Algarve, Universite
de la Méditerranée, Centre d'Océanologie de Marseille,
UMR CNRS 6540 Dimar (UMRCNRS 6540 DIMAR), Stazione
Zoologica "Anton Dohrn".
- Person-months: Universidad de Oviedo (32), Universidade do Algarve (8), Universite
de la Méditerranée, Centre d'Océanologie de Marseille,
UMR CNRS 6540 Dimar (UMRCNRS 6540 DIMAR) (12), Stazione Zoologica "Anton
Dohrn". (24)
OBJECTIVES
The main objectives are:
1) to assess the biodiversity status of the main communities successfully invaded by an introduced seaweed and
2) to evaluate the changes in the structure of native communities dominated by seaweeds after the establishment of an invasive seaweed species using two levels of study:
..............1) in rockpools and
..............2) at a stablished mature community.
WORKPLAN
Hypothesis:
1) Species-rich communities should be less susceptible to invasion because of a more complete utilization of resources.
2) Removal of invasive seaweed species
promotes the growth of native canopy species.
Location selection:This schedule will be carried out at those locations
where mid or lowshore native seaweed communities have been recently invaded
by invasive seaweeds altering the community structure.
Shore selection: Three semiexposed shores should be chosen in an area
that has been recently colonized by invasive seaweeds.
HYPOTHESIS 1:
Considering that rockpools might be like islands, we want to know the biodiversity of them after the colonization by an invasive seaweed.
Plot selection: All rockpools should be located at the same community
Replications: Six rockpools to belong the categories cited below.
Methods: Where practicable, 6 categories of rockpools should be chosen attending to their size (large, medium and small) and depth (shallow and deep).
Sampling: The plots will be sampled at
the begining of the project, in order to do a complete list of seaweed
species as well as the abundance of the main species. Percentage cover
of each identifiable taxon will be estimatted visually and then, a complete
collect of those non easily identifiable species should be done and translate
to the laboratory for identification.
Required work per location
3 shores
6 rockpools categories
6 replicates
36 plots per shore
HYPOTHESIS 2:
Removal of invasive species promotes the growth of native canopy species.
a) Mature community
Plot selection: Randomly selected plots should be established meeting
the following criteria:
-gentle sloping area
-100% algal cover
-not < 2m from any other plot
These plots will be designated and then randomly allocated to each treatment.
Timing: Experiments should be established during two different seasons (i.e. winter and summer).
Replications:At each start date six replicates per treatment will be established.
Methods: Where practicable, each experimental
plot is 50 cm x 50 cm located in the centre of a 1m x 1m buffer zone.
Probably, in the Mediterranean alternative plot size would be needed.
Plots should be marked at the corners using tags anchored to stainless
screws fixed into plastic plugs set into holes drilled in the rock. Rubber
bands are placed on the screws to hold down the tag.
Treatments: Two treatments are involved
1.- Control: corners marked but not manipulated
in any other way
2.- Invader exclusion: all thalli of the selected invader regularly removed
Monitoring: Monitoring will be carried
out bimonthly until the end of the experiment (24 or 48 months).
On each monitoring occasion all invaders colonizing plots of treatment
2 should be removed.
The plots will be monitored visually to non-destructive assess percentage
cover of each identifiable algal taxon (where possible this will be to
species level). Percentage cover will be estimated by using a 60 cm x
60 cm square with a double grid each 5 cm (100 intersection points) overlaid
on the plot. Encrusting, understorey and canopy layers will be assesed
separately so total cover may exceed 100%. Species present but not recorded
at any intersection point are scored as 1%.
Required work per location3 shores
2 seasons
2 treatments
6 replicates
12 plots per shore x 2 seasons = 24 plots per shore
b) Rockpools
Plot selection, timing, replication and methods: Same as in hypothesis 1.
Treatments: All thalli of the selected invader should be removed
Monitoring: At the end of the experiment (24 or 48 months) the plots should be sampled as in hypothesis 1.
DELIVERABLES
D2: Scientific paper(s) on the impactof invaders on seaweed communities
MILESTONES
Month 2: sites and species for experiments
selected
Month 7: Experimental set up completed. Start of experiments
Month 20: First results (one year) analyzed
