Impacts of green tides on flatfish communities and individual - - PowerPoint PPT Presentation
Impacts of green tides on flatfish communities and individual performances Emilie Le Luherne, Olivier Le Pape & Elodie Rveillac Flatfish symposia Flatfish ecology From genomics to ecosystems November 11-16, 2017 Saint Malo, France
Emilie Le Luherne, Olivier Le Pape & Elodie Réveillac
Impacts of green tides on flatfish – Flatfish symposia – November 16, 2017
Flatfish symposia
Flatfish ecology – From genomics to ecosystems November 11-16, 2017 Saint Malo, France
Coastal zones and estuaries
Life cycle of marine nursery-dependent fish species
These systems encompass essential fisheries habitats
44% of the ICES species are dependent on these areas 77% of the commercial landings (Seitz et al., 2014)
Introduction Materials et methods Conclusion Community scale Individual scale
Impacts of green tides on flatfish – Flatfish symposia – November 16, 2017 Emilie Le Luherne
Impacts of green tides on flatfish – Flatfish symposia – November 16, 2017
Coastal zones and estuaries
These systems encompass essential fisheries habitats
44% of the ICES species are dependent on these areas 77% of the commercial landings (Seitz et al., 2014)
Nursery habitats (Beck et al.,2001)
Life cycle of marine nursery-dependent fish species
Introduction Materials et methods Conclusion Community scale Individual scale
Emilie Le Luherne
Areas with economical interests (urbanisation, fishery, industry
et tourism)
Anthropogenic activities threaten these habitats
(Lotze et al., 2006; Halpern et al., 2008)
Coastal zones and estuaries
Introduction Materials et methods Conclusion Community scale Individual scale
Impacts of green tides on flatfish – Flatfish symposia – November 16, 2017 Emilie Le Luherne
Credit : SIPA Credit : USDA
(Fletcher, 1996; Merceron et al., 2007)
Coastal zones and estuaries
Introduction Materials et methods Conclusion Community scale Individual scale
Areas with economical interests (urbanisation, fishery, industry
et tourism)
Anthropogenic activities threaten these habitats
(Lotze et al., 2006; Halpern et al., 2008)
Impacts of green tides on flatfish – Flatfish symposia – November 16, 2017 Emilie Le Luherne
(Fletcher, 1996; Merceron et al., 2007)
Credit : SIPA Credit : USDA
Areas with economical interests (urbanisation, fishery, industry
et tourism)
Anthropogenic activities threaten these habitats
(Lotze et al., 2006; Halpern et al., 2008)
Coastal zones and estuaries
Emilie Le Luherne Impacts of green tides on flatfish – Flatfish symposia – November 16, 2017
Introduction Materials et methods Conclusion Community scale Individual scale
What are green tides ?
From CEVA, 1998
Natural phenomenon driven by different seasonal limiting factors (Fletcher, 1996;
Merceron et al., 2007)
Credit : Arirao
Massive proliferation of opportunistic green macroalgae
Credit : CEVA
Emilie Le Luherne Impacts of green tides on flatfish – Flatfish symposia – November 16, 2017
Introduction Materials et methods Conclusion Community scale Individual scale
From Yé, 2011 From CEVA, 2011
In the world In Northwestern France
Credit : fourweekdiary Credit : fourweekdiary Credit : marcelgreen.fr
In nutrient enriched sublittoral areas with a slight slope and low residual hydrodynamic conditions
more than 80 sites
Green tides location
Emilie Le Luherne Impacts of green tides on flatfish – Flatfish symposia – November 16, 2017
Introduction Materials et methods Conclusion Community scale Individual scale
Formation processes
(e.g. Fletcher, 1996; Merceron et al., 2007)
Green tides: multiple habitat perturbations
Introduction Materials et methods Conclusion Community scale Individual scale
Impacts of green tides on flatfish – Flatfish symposia – November 16, 2017 Emilie Le Luherne
Chemical perturbations
Trophic perturbations
Physical perturbations
habitat structure and complexity
Formation processes
(e.g. Fletcher, 1996; Merceron et al., 2007) (Fletcher, 1996; Raffaelli et al., 1998)
Green tides: multiple habitat perturbations
Introduction Materials et methods Conclusion Community scale Individual scale
Impacts of green tides on flatfish – Flatfish symposia – November 16, 2017 Emilie Le Luherne
Chemical perturbations
Trophic perturbations
Physical perturbations
habitat structure and complexity
Formation processes
(e.g. Fletcher, 1996; Merceron et al., 2007) (Fletcher, 1996; Raffaelli et al., 1998)
Green tides: multiple habitat perturbations
Introduction Materials et methods Conclusion Community scale Individual scale
Impacts of green tides on flatfish – Flatfish symposia – November 16, 2017 Emilie Le Luherne
Chemical perturbations
Trophic perturbations
Physical perturbations
habitat structure and complexity
Studies on the benthic macrofauna
1996a, 1996b) and trophic webs (e.g. Quillien et al., 2015; 2016)
1985; Harder et al, 2004)
Formation processes
(e.g. Fletcher, 1996; Merceron et al., 2007) (Fletcher, 1996; Raffaelli et al., 1998)
Green tides: multiple habitat perturbations
Introduction Materials et methods Conclusion Community scale Individual scale
Impacts of green tides on flatfish – Flatfish symposia – November 16, 2017 Emilie Le Luherne
Meta-analysis on the effect of green tides on the entire intertidal community (Lyons et al., 2014) Few studies on ichthyofauna
Chemical perturbations
Trophic perturbations
Physical perturbations
habitat structure and complexity
Formation processes
(e.g. Fletcher, 1996; Merceron et al., 2007) (Fletcher, 1996; Raffaelli et al., 1998)
Green tides: multiple habitat perturbations
Introduction Materials et methods Conclusion Community scale Individual scale
Impacts of green tides on flatfish – Flatfish symposia – November 16, 2017 Emilie Le Luherne
Chemical perturbations
Trophic perturbations
Physical perturbations
habitat structure and complexity
Formation processes
(e.g. Fletcher, 1996; Merceron et al., 2007) (Fletcher, 1996; Raffaelli et al., 1998)
Green tides: multiple habitat perturbations Objective
Characterise the effect of green tides on the role of intertidal habitats for flatfish ?
Introduction Materials et methods Conclusion Community scale Individual scale
Impacts of green tides on flatfish – Flatfish symposia – November 16, 2017 Emilie Le Luherne
What are the effects of green tides on fish community and especially on flatfish community?
Individual Community
Introduction Materials et methods Conclusion Community scale Individual scale
Impacts of green tides on flatfish – Flatfish symposia – November 16, 2017 Emilie Le Luherne
Which physiological processes are implemented by a flatfish species to accomodate the perturbation?
Sandy beach Estuarine mudflat
N
Control Impacted Control Impacted Sandy beach
Bay of Saint Brieuc
Estuarine mudflat
Rance estuary
Interannual cover rate from CEVA < 1% 5 10 50 >75%
Study areas
Introduction Materials et methods Conclusion Community scale Individual scale
Impacts of green tides on flatfish – Flatfish symposia – November 16, 2017 Emilie Le Luherne
Sampling protocol
Impacted site Control site
From CEVA, 1998
every 15 days from april to october in 2013 and 2014
Approach
Introduction Materials et methods Conclusion Community scale Individual scale
Impacts of green tides on flatfish – Flatfish symposia – November 16, 2017 Emilie Le Luherne
Sampling protocol
6 sampling at each site
Dissolved oxygen concentration, pH) and sediment structure
Ichthyofauna sampling
Trawl net (juveniles and adults)
mesh: 8 mm
Identification and count Trawling Measures and samplings
Total lenght Dorsal muscle Otoliths
Impacted site Control site
Introduction Materials et methods Conclusion Community scale Individual scale
Impacts of green tides on flatfish – Flatfish symposia – November 16, 2017 Emilie Le Luherne
Dissolved oxygen concentration, pH) and sediment structure
Ichthyofauna sampling Macroalgae biomass and estimation of each macroalgae morphotype percentage
Sampling protocol
6 sampling at each site
Impacted site Control site
Filamentous green macroalgae Other macroalgae (e.g. Fucus spp.)
Credit : CEVA Credit : univ-lille1 Credit : algaeBASE
Expanded blade Ulva spp.
Introduction Materials et methods Conclusion Community scale Individual scale
Impacts of green tides on flatfish – Flatfish symposia – November 16, 2017 Emilie Le Luherne
What are the effects of green tides on fish community and especially on flatfish community?
Community
On the community scale
Introduction Materials et methods Conclusion Community scale Individual scale
Impacts of green tides on flatfish – Flatfish symposia – November 16, 2017 Emilie Le Luherne
Sandy beach
Sandy beach
Introduction Materials et methods Conclusion Community scale Individual scale
Impacts of green tides on flatfish – Flatfish symposia – November 16, 2017 Emilie Le Luherne
Sandy beach
2013 2014
Fish community
Density (log10.ha-1) Species richness Ulva spp. density (kg.m-2)
April May June July Aug Sept Oct
Macroalgae proliferation
2013
Negative effect on species richness
During green tides
April May June July Aug Sept Oct
Control Impacted
Before During After Before During Dur After Max
April May June July Aug Sept Oct April May June July Aug Sept Oct
Credit : CEVA
Expanded blade Ulva spp.
Introduction Materials et methods Conclusion Community scale Individual scale
Impacts of green tides on flatfish – Flatfish symposia – November 16, 2017 Emilie Le Luherne
Sandy beach
2013 2014
Fish community
Density (log10.ha-1) Species richness Ulva spp. density (kg.m-2)
April May June July Aug Sept Oct
Macroalgae proliferation
2013
Negative effect on species richness
During green tides
April May June July Aug Sept Oct
Control Impacted
Before During After Before During Dur After Max
April May June July Aug Sept Oct April May June July Aug Sept Oct
Credit : CEVA
Introduction Materials et methods Conclusion Community scale Individual scale
Impacts of green tides on flatfish – Flatfish symposia – November 16, 2017 Emilie Le Luherne
Medium proliferation Weak proliferation
Expanded blade Ulva spp.
Maximum /2
Sandy beach
2013 2014
Fish community
Density (log10.ha-1) Species richness Ulva spp. density (kg.m-2)
April May June July Aug Sept Oct
Before/After Control/Impact
2013
Negative effect on species richness
During green tides
April May June July Aug Sept Oct
Control Impacted
Before During After Before During Dur After Max
April May June July Aug Sept Oct April May June July Aug Sept Oct
Before During
= After
Before During
= After
Credit : CEVA
Introduction Materials et methods Conclusion Community scale Individual scale
Impacts of green tides on flatfish – Flatfish symposia – November 16, 2017 Emilie Le Luherne
Macroalgae proliferation
Expanded blade Ulva spp.
Sandy beach
2013 2014
Fish community
Density (log10.ha-1) Species richness Ulva spp. density (kg.m-2)
April May June July Aug Sept Oct
Species richness and density
Before/After Control/Impact
Negative effect on species richness during the medium proliferation
During green tides
April May June July Aug Sept Oct
Control Impacted
Before During After Before During Dur After Max
Before During
= After
Before During
= After
Introduction Materials et methods Conclusion Community scale Individual scale
Impacts of green tides on flatfish – Flatfish symposia – November 16, 2017 Emilie Le Luherne
Sandy beach
nMDS on species with an occurrence > 5%
Species community composition during green tides
2013 2014
Introduction Materials et methods Conclusion Community scale Individual scale
Impacts of green tides on flatfish – Flatfish symposia – November 16, 2017 Emilie Le Luherne
Estuarine mudflat
Estuarine mudflat
Introduction Materials et methods Conclusion Community scale Individual scale
Impacts of green tides on flatfish – Flatfish symposia – November 16, 2017 Emilie Le Luherne
Estuarine mudflat
Fish community
Density (log10.ha-1) Species richness Macroalage density (kg.m-2)
2014
Negative effect on species richness
During green tides
2014
April May June July Aug Sept Oct
Control Impacted
BeforeApril May June July Aug Sept Oct
Filamentous green macroalgae
Credit : CEVA Credit : univ-lille1
Introduction Materials et methods Conclusion Community scale Individual scale
Impacts of green tides on flatfish – Flatfish symposia – November 16, 2017 Emilie Le Luherne
Macroalgae proliferation
Ulva spp. (blade) – Impacted Filamentous green macroalgae – Impacted Filamentous green macroalgae – Control
Expanded blade Ulva spp.
During
Estuarine mudflat
Fish community
Density (log10.ha-1) Species richness Macroalage density (kg.m-2)
2014
Control/Impacted
Negative effect on species richness
During green tides
2014
April May June July Aug Sept Oct
Control Impacted
BeforeApril May June July Aug Sept Oct
Filamentous green macroalgae
Credit : CEVA Credit : univ-lille1
Introduction Materials et methods Conclusion Community scale Individual scale
Impacts of green tides on flatfish – Flatfish symposia – November 16, 2017 Emilie Le Luherne
Macroalgae proliferation
During
Ulva spp. (blade) – Impacted Filamentous green macroalgae – Impacted Filamentous green macroalgae – Control
Expanded blade Ulva spp.
During
Estuarine mudflat
Fish community
Density (log10.ha-1) Species richness Macroalage density (kg.m-2)
2014
Control/Impacted
Negative effect on species richness
During green tides
2014
April May June July Aug Sept Oct
Control Impacted
BeforeIntroduction Materials et methods Conclusion Community scale Individual scale
Impacts of green tides on flatfish – Flatfish symposia – November 16, 2017 Emilie Le Luherne
During
Ulva spp. (blade) – Impacted Filamentous green macroalgae – Impacted Filamentous green macroalgae – Control
Species richness and density
During
Estuarine mudflat
Species community composition during green tides
2014
nMDS on species with an occurrence > 5%
Introduction Materials et methods Conclusion Community scale Individual scale
Impacts of green tides on flatfish – Flatfish symposia – November 16, 2017 Emilie Le Luherne
What are the effects of green tides on fish community and especially on flatfish community?
green tides Community
On the community scale
Introduction Materials et methods Conclusion Community scale Individual scale
Impacts of green tides on flatfish – Flatfish symposia – November 16, 2017 Emilie Le Luherne
Which physiological processes are implemented by a flatfish species to accomodate the perturbation?
Individual Community
On the individual scale
Introduction Materials et methods Conclusion Community scale Individual scale
Impacts of green tides on flatfish – Flatfish symposia – November 16, 2017 Emilie Le Luherne
What are the effects of green tides on fish community and especially on flatfish community?
green tides
Environmental perturbation
Response time
Instantaneaous responses
Antioxidant defence capacity
Short-term and mid-term responses
Muscle total lipids, morphometric condition and growth rate
Pleuronectes platessa
Size range [31-76] mm
On the individual scale
Introduction Materials et methods Conclusion Community scale Individual scale
Impacts of green tides on flatfish – Flatfish symposia – November 16, 2017 Emilie Le Luherne
2013 2014
Number of plaice available
Ulva spp. density (kg.m-2) 25 20 15 10 5
Number of plaice at the impacted site Introduction Materials et methods Conclusion Community scale Individual scale
Impacts of green tides on flatfish – Flatfish symposia – November 16, 2017 Emilie Le Luherne
2013 2014
Number of plaice available
Ulva spp. density (kg.m-2) 25 20 15 10 5
Number of plaice at the impacted site Introduction Materials et methods Conclusion Community scale Individual scale
Impacts of green tides on flatfish – Flatfish symposia – November 16, 2017 Emilie Le Luherne
2 dates of sampling at the onset of the green tides
Instantaneous responses
Antioxidant defence capacity – Trolox Equivalent Antioxidant Capacity (TEAC)
Before During After
April May June July Aug Sept Oct Ulva spp. density (kg.m-2)
Introduction Materials et methods Conclusion Community scale Individual scale
Impacts of green tides on flatfish – Flatfish symposia – November 16, 2017 Emilie Le Luherne
Significant increase in juvenile plaice antioxidant defence capacity
Instantaneous responses
Antioxidant defence capacity – Trolox Equivalent Antioxidant Capacity (TEAC)
Before During After
TEAC (mM Trolox equivalent / mg of soluble proteins) April May June July Aug Sept Oct Control Impacted Ulva spp. density (kg.m-2)
Introduction Materials et methods Conclusion Community scale Individual scale
Impacts of green tides on flatfish – Flatfish symposia – November 16, 2017 Emilie Le Luherne
C = 6 I = 7
Muscle total lipid C:N ratio R morphometric index
2013 2014
Muscle total lipid and morphometric condition indices
Short-term and mid-term responses
Better morphometric condition at the onset of green tides in 2014
C = 5 I = 5 C = 11 I = 6 C = 9 I = 6 C = 32 I = 7
Introduction Materials et methods Conclusion Community scale Individual scale
Impacts of green tides on flatfish – Flatfish symposia – November 16, 2017 Emilie Le Luherne
2014 2013
February March April May March April May
Daily growth rates (µm.j-1)
In nursery areas
Growth index – Daily growth rate (DGR)
Short-term and mid-term responses
Control Impacted
v v
Before During
Introduction Materials et methods Conclusion Community scale Individual scale
Impacts of green tides on flatfish – Flatfish symposia – November 16, 2017 Emilie Le Luherne
Cohort 1 Cohort 1 Cohort 2
Before Before During Dur
2014 2013
February March April May March April May
Daily growth rates (µm.j-1)
Short-term and mid-term responses
Control Impacted
v v
In nursery areas
Large juvenile plaice during green tides lower DGR at the impacted site than at the control site
Introduction Materials et methods Conclusion Community scale Individual scale
Impacts of green tides on flatfish – Flatfish symposia – November 16, 2017 Emilie Le Luherne
Cohort 1 Cohort 1
Before Before During Dur
Growth index – Daily growth rate (DGR)
2014 2013
March April May
Daily growth rates (µm.j-1)
Short-term and mid-term responses
Control Impacted
v v Small juvenile plaice higher DGR at the impacted site than at the control site Large juvenile plaice during green tides lower DGR at the impacted site than at the control site
*C < I In nursery areas **C < I
Introduction Materials et methods Conclusion Community scale Individual scale
Impacts of green tides on flatfish – Flatfish symposia – November 16, 2017 Emilie Le Luherne
February March April May
Cohort 1 Cohort 1 Cohort 2
Before During Before Before During Dur
Growth index – Daily growth rate (DGR)
2014 2013
February March April May March April May
Daily growth rates (µm.j-1)
Short-term and mid-term responses
Control Impacted
v v
*C < I In nursery areas **C < I
Introduction Materials et methods Conclusion Community scale Individual scale
Impacts of green tides on flatfish – Flatfish symposia – November 16, 2017 Emilie Le Luherne
≠ plaice response according to their size:
Bonhommeau, 2015)
Cohort 1 Cohort 1 Cohort 2
Before During Before Before During Dur
Growth index – Daily growth rate (DGR)
Progressive integration of green tide effect on the individual scale
Introduction Materials et methods Conclusion Community scale Individual scale
Impacts of green tides on flatfish – Flatfish symposia – November 16, 2017 Emilie Le Luherne
Instantaneous responses
Increase of antioxidant defence capacity
Short-term and mid-term responses
No measured effect on lipid content and morphometric condition Larger plaice have a lower growth rate
When macroalgae proliferation maintain or increase plaice disappear from the impacted site
Weak capacity to migrate at this stage
(Burrows et al., 2004)
Two complementary scale of analysis
Which physiological processes are implemented by a flatfish species to accomodate the perturbation?
increase of the perturbation mostly due to the death of individuals Individual Community
Unsuitable nursery ground for flatfish
Introduction Materials et methods Conclusion Community scale Individual scale
Impacts of green tides on flatfish – Flatfish symposia – November 16, 2017 Emilie Le Luherne
What are the effects of green tides on fish community and especially on flatfish community?
green tides
Emilie Le Luherne
Impacts of green tides on flatfish – Flatfish symposia – November 16, 2017
Density of veritcal distribution guilds (log10.ha-1)
Before/After Control/Impact
2013 2014
Sandy beach
Vertical distribution guilds
2013
Negative effect on demersal and benthic species During green tides
April May June July Aug Sept Oct Control Impacted April May June July Aug Sept Oct
Ulva spp. density (kg.m-2) pelagic demersal benthic Annex
Estuarine mudflat
Vertical distribution guilds
Control/Impacted During green tides
Ulva spp. (blade) – Impacted Filamentous green macroalgae – Impacted Filamentous green macroalgae – Control
April May June July Aug Sept Oct
Control Impacted
During
Density of vertical distribution guilds (log10.ha-1)
Negative effect on demersal and benthic species
pelagic demersal benthic Macroalage density (kg.m-2)
2014
Annex
Trawl capturability during green tides?
Annex
Ulva spp. density (kg.m-2) Fish density.ha-1
Pylaiella littoralis
Credit : algaeBASE
Macroalgae density (kg.m-2)
April May June July Aug Sept Oct
2013
Annex
Trawl capturability during green tides?
Fish were captured during high biomass
Pylaiella littoralis
Credit : algaeBASE
Ulva spp. density > 0.3kg.m-2 Few or no fish captured but shrimp are still captured
trawl is still fishing
0.55 kg.m-2 density 0.33 m-2
control
density 0.4 m-2
impacted
2013
Annex
Trawl capturability during green tides?
Fish were captured during high biomass
Macroalgae density (kg.m-2)
April May June July Aug Sept Oct
Fish were captured during high biomass
Pylaiella littoralis
Credit : algaeBASE
Ulva spp. density > 0.3kg.m-2 Few or no fish captured but shrimp are still captured
trawl is still fishing
Capturability test 50 kg
Ulva spp. Fish
50 kg
50 m 25 m
Annexes
Trawl capturability during green tides?
Macroalgae density (kg.m-2)
April May June July Aug Sept Oct
Physico-chemical parameters in 2014
Annexes
Salinity
April May June July Aug Sept Oct
Temperature (°C) Dissolved
pH
Sandy beach Estuarine mudflat
April May June July Aug Sept Oct