Monitoring of benthic fauna in western Sweden

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Monitoring of benthic fauna in western Sweden

• Ass. Prof. Mats Lindegarth
• Tjärnö Marine Biological Laboratory
• Dept. of Marine Ecology /
• Göteborg University Marine Research Centre

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Contents

• Design of monitoring programme (2001)
• Background
• Design and initial analyses
• A priori calculations of power (2006)
• How do we specify hypotheses?
• Power of tests
• Conclusions

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Background

• Coordinate national and regional monitoring
• Modify within budget
• Requirements of the WFD?
• Areas vs stations!
• Variables, criteria, BQI?

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Near- and offshore monitoring
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Extended monitoring in nearshore areas
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Initial analyses of data from 1998-1999

• Significant changes!
• Power 1.0!
• Specify hypotheses!

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Hypotheses What do we really want to know?
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Technical aspects

• Affects how we test for effects
• Planned contrasts

• Scales?
• Affects how we calcualate power!

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Modelling of power (2006)

• Model a decrease in abundance, richness and BQI
  by 5 -80.
• Calculate the non-centrality parameter, l, for
  different degrees of change.

• Determine power by comparing the oserved l to a
  known relationship between l and power.

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Power vs l
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Power in nearshore areas consistent change
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Power in nearshore areaschange in one area
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Nearshore Skagerrak vs whole area
3 areas8 locations2 samples Total 48
2 basins2 exposures3 locations4 samples Total
48
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Deviation from class limits for BQI
BQI
Time

• Similar procedures easily applicable!
• One-sided tests?!

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Conclusions

• Current programmes
• can detect environmental changes
• Need to specify which type of changes we want to
  detect and how can this be done analytically?

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Tack!