232
draw a more integrated picture representing the functional
role of macrobenthic community bioturbation in ecosystem
functioning. In the frame of the 2017 YOUMARES conference in Kiel, I will present sampling and experimental methods. The main focus will be on the experimental set up in the
mesocosm and macrobenthic community respiration measurements. Further I will present some initial results, showing the comparison in macrobenthic respiratory response to
varying environmental stressors (hypoxia & heat waves).
10.4 Session Report
The session was attended by 30–40 participants and chaired
by Camilla Sguotti and Xochitl Cormon.
First, a general introduction about regime shift theory was
given by Sguotti and Cormon. Afterwards, there were 2 h of
in total seven oral presentations, three poster presentations
and a session wrap-up conducted interactively with the
audience.
Most of the studies presented were experimental studies
investigating potential drivers (parameters and state variables; Folkers, Earp, Straub, Chi, van de Ven & Rombouts
and Böhmer). Interestingly, most studies were related to
bottom-up control (nutrients and temperature). Coastal systems dynamics were most studied (Folkers, Earp, Straub,
Lachs, and Böhmer); followed by pelagic systems (Färber,
Chi, Rubio, and Sguotti) and the deep-sea (van de Ven &
Rombouts). Pelagic studies were the only ones exploring
time series (Färber, Rubio, and Sguotti) and focusing on
either commercial fish stocks (herring and cod) or fishing
effort (tuna fleets) to detect potential regime shifts. No studies on management applications were presented but four
studies (Rubio, Lachs, Sguotti, and Färber) were directly
linked to management in their objectives. Most of the current
and known regime shift related issues were highlighted in the
session:
• Difficulty in regime shift detection
All the three studies aiming to understand non-linear
dynamics of fish stocks (Färber, Rubio, and Sguotti) highlighted the difficulty to recognized regime shifts. For example, Färber highlighted the difficulty to disentangle abrupt
changes and natural oscillations using three different models
to analyze herring spawning stock biomass and recruitment
dynamics, each model providing a different vision of these
dynamics.
• Hysteresis and feedback mechanisms
Hysteresis phenomena were evidenced in the study of
Straub, where after a heatwave, kelp always ended up bleaching if not even dying. Sguotti showed that most of Atlantic
cod stock never recovered even after management measures,
while van de Ven & Rombouts evidenced a feedback loop in
deep sea sponges and DOM structuring the system (as known
in coral reefs).
• Requirement of large amounts of data
All the studies highlighted the need of “big data” provided by long and extensive monitoring and/or experiments.
For example, the studies of Sguotti, Färber, and Earp were
constrained by the availability of life-history trait information, which may be key to detect/understand the regime
shifts: e.g., age-at-maturation, growth rate, etc., while
Rubio’s study of tune fishery effort spatial distribution was
limited to purse-seine fleet analysis, which resolution was
fine enough compared to the other gears data.
• Requirement of high technical skills and equipment
Challenges related to statistical analysis (Färber and
Sguotti), high-tech material (van de Ven & Rombouts), or
chemical compose manipulation (Earp) were highlighted as
limitation to the study of various systems/drivers.
• Scale issues
Straub highlighted how temporal scales matters in the
reaction of kelp forest to heatwaves showing an important
lag response as well as the importance of heatwave duration.
The studies of Böhmer and Folkers were limited in their
experimental time and might have shown different results
with longer experiment durations. Spatial scales issues were
highlighted by the studies of Lachs and Rubio.
• Multiple drivers, interactive and cumulative effects
Most of the experimental studies generally focused of two
drivers or more (Folkers, Earp, Sandra, Chi, and Böhmer)
and generally encountered challenges trying to disentangle
the various drivers potentially impacting their system of
interest.
• Stakeholder conflicts and governance issues
The studies of Earp and Lachs both highlighted potential
conflicts concerning marine space and resource use (heavy
vs eco-tourism, conservation, fishery, etc.) and the necessity
of cooperation between the different involved stakeholders
and the different scales of governance organization.
To conclude, this session managed to directly highlight
the current issues related to the topic through the content of
the presented studies. Indirectly, it also highlighted the curAppendices
draw a more integrated picture representing the functional
role of macrobenthic community bioturbation in ecosystem
functioning. In the frame of the 2017 YOUMARES conference in Kiel, I will present sampling and experimental methods. The main focus will be on the experimental set up in the
mesocosm and macrobenthic community respiration measurements. Further I will present some initial results, showing the comparison in macrobenthic respiratory response to
varying environmental stressors (hypoxia & heat waves).
10.4 Session Report
The session was attended by 30–40 participants and chaired
by Camilla Sguotti and Xochitl Cormon.
First, a general introduction about regime shift theory was
given by Sguotti and Cormon. Afterwards, there were 2 h of
in total seven oral presentations, three poster presentations
and a session wrap-up conducted interactively with the
audience.
Most of the studies presented were experimental studies
investigating potential drivers (parameters and state variables; Folkers, Earp, Straub, Chi, van de Ven & Rombouts
and Böhmer). Interestingly, most studies were related to
bottom-up control (nutrients and temperature). Coastal systems dynamics were most studied (Folkers, Earp, Straub,
Lachs, and Böhmer); followed by pelagic systems (Färber,
Chi, Rubio, and Sguotti) and the deep-sea (van de Ven &
Rombouts). Pelagic studies were the only ones exploring
time series (Färber, Rubio, and Sguotti) and focusing on
either commercial fish stocks (herring and cod) or fishing
effort (tuna fleets) to detect potential regime shifts. No studies on management applications were presented but four
studies (Rubio, Lachs, Sguotti, and Färber) were directly
linked to management in their objectives. Most of the current
and known regime shift related issues were highlighted in the
session:
• Difficulty in regime shift detection
All the three studies aiming to understand non-linear
dynamics of fish stocks (Färber, Rubio, and Sguotti) highlighted the difficulty to recognized regime shifts. For example, Färber highlighted the difficulty to disentangle abrupt
changes and natural oscillations using three different models
to analyze herring spawning stock biomass and recruitment
dynamics, each model providing a different vision of these
dynamics.
• Hysteresis and feedback mechanisms
Hysteresis phenomena were evidenced in the study of
Straub, where after a heatwave, kelp always ended up bleaching if not even dying. Sguotti showed that most of Atlantic
cod stock never recovered even after management measures,
while van de Ven & Rombouts evidenced a feedback loop in
deep sea sponges and DOM structuring the system (as known
in coral reefs).
• Requirement of large amounts of data
All the studies highlighted the need of “big data” provided by long and extensive monitoring and/or experiments.
For example, the studies of Sguotti, Färber, and Earp were
constrained by the availability of life-history trait information, which may be key to detect/understand the regime
shifts: e.g., age-at-maturation, growth rate, etc., while
Rubio’s study of tune fishery effort spatial distribution was
limited to purse-seine fleet analysis, which resolution was
fine enough compared to the other gears data.
• Requirement of high technical skills and equipment
Challenges related to statistical analysis (Färber and
Sguotti), high-tech material (van de Ven & Rombouts), or
chemical compose manipulation (Earp) were highlighted as
limitation to the study of various systems/drivers.
• Scale issues
Straub highlighted how temporal scales matters in the
reaction of kelp forest to heatwaves showing an important
lag response as well as the importance of heatwave duration.
The studies of Böhmer and Folkers were limited in their
experimental time and might have shown different results
with longer experiment durations. Spatial scales issues were
highlighted by the studies of Lachs and Rubio.
• Multiple drivers, interactive and cumulative effects
Most of the experimental studies generally focused of two
drivers or more (Folkers, Earp, Sandra, Chi, and Böhmer)
and generally encountered challenges trying to disentangle
the various drivers potentially impacting their system of
interest.
• Stakeholder conflicts and governance issues
The studies of Earp and Lachs both highlighted potential
conflicts concerning marine space and resource use (heavy
vs eco-tourism, conservation, fishery, etc.) and the necessity
of cooperation between the different involved stakeholders
and the different scales of governance organization.
To conclude, this session managed to directly highlight
the current issues related to the topic through the content of
the presented studies. Indirectly, it also highlighted the curAppendices