Environmental monitoring at Havsul-1

Thomas Dahlgren, Marie-Lise Schläppy, Aleksej Shashkov, Mathias Andersson, Yuri Rzhanov, Ilker Fer and Erling Heggøy

Presented by Dominique Durand – Uni Research

Why wind farms at exposed places?

Wind resource

High average wind speeds

Competing activities

Avoided by merchant

vessels

Low activity from trawl

fisheries on rocky sea bed

Thomas Dahlgren

Potential impacts of offshore wind farms

Sea current and wave patterns

Sea bed disturbances during construction: impact on benthic

communities, fish stocks, loss of food sources, alterations in

productivity and composition

Noise generated during construction especially the noise

stemming from pile driving. Kill or injure fish and marine

mammals, hearing loss and disorientation. Species may abandon

areas ranging up to several kilometers from the construction site,

impact on spawning and juvenile stages of many species

Bird: risk of collisions with the wind turbine blades. Migration barrier

Baseline & monitoring programBefore After Control Impact design

Havsul

Reference

area

Ålesund• Two years baseline

• BACI design

• One reference area

Thomas Dahlgren

Explore and mitigate the possible negative impacts of

offshore wind farms on the marine environment

Havsul-1

Thomas DahlgrenMultiBeam bathymetry

Wave regime at Havsul

Golmen 2007 Dahlgren et. al., in press

Thomas Dahlgren

Storm events

Havsul habitat

• Most common habitat

• Species rich

• Hard to sample

• Little known

• Kelp with epifauna

• Uncrusted algae

• Sea urchins/ sea

stars

• Demersal fish

Typical Havsul seabed

Thomas Dahlgren

New species discovered in the Havsul area

Offshore high energy sites

• Remote

• Unknown fauna &

ecology

• Impact hard to predict

Thomas Dahlgren

Methods used for baseline study (marine biology)

Grab samples in the deeper soft bottom areas

Kelp samples for associated fauna

Video image data for rocky surface areas (ROV)

Passive fishing gear (use of local fishermen)

Marine mammals (harbor porpoise) noise detectors

(C-pods)

Haul-out site seal count (airborne)

Thomas Dahlgren

Results from the Havsul baseline— Porpoise Detection Positive Minutes

Photo: Mathias Andersson

Ballast

C-Pod

Acoustic

release

Buoyancy

Thomas Dahlgren

1st time in Norway: paper in prep.

0

20

40

60

DP

M/ d

ay

Wind farm sites

0

20

40

60

DM

P/ d

ay

Control sites

0

10

20

30

Win

d s

pe

ed

(m

/s)

Date

Wind speed

June July August September

• Havsul: 2012 Jun-Sep

monthly averages ca. 5-11

DPM/day

• Belgium: Oct-May

monthly averages ca. 9-32

DPM/day

• Havsul: no correaltion

between DPM/day and

wind regime

(Andersson, et. al. unpubl)

(Haelters et. al. 2010)

Results from the Havsul baseline— Porpoise Detection Positive Minutes

Thomas Dahlgren

Results from the Havsul baseline — Seabed video data (ROV)

• Mosaic from video

• Biological data extraction from mosaic

• Predictor data (e.g. seabed ruggedness) from

multibeam swaths

• General linear models to test what factor (e.g.

ruggedness) explains distribution of features (e.g. sea

urchins)

Thomas Dahlgren

Results from the Havsul baseline — Seabed video data

• Sea star abundance (from

video transects) positively

correlated to ruggedness

• Flattening seabed for

foundations may remove sea

star habitat

Thomas Dahlgren

Benthic Terrain Modeller = ruggedness (from multibeam data)

Results from the Havsul baseline — Seabed video data

• Kelp abundance positively

correlated to Aspect (slope

direction/light)

• Shading southerly slopes

may degrade kelp habitat

Thomas Dahlgren

Conclusions from the Baseline study

Few hypotheses on impact

Video data from ROV: appropriate method for

assessing impacts in high-energy rocky-shore habitat

Small and quick boats are able to use weather

windows

Risk of using moorings and other fixed instruments

Marine operations largely limited to summer due to

weather (and light at high latitudes)

Thomas Dahlgren

Hypotheses on impacts

Monitoring not implemented in Norcowe

Limited research to developing proper methodological

approaches

Removal of trawling pressure gives a significant

positive impact that shades away the possible

impacts of the wind farm itself

Mill’s mast can be seen an artificial reef with possible

positive impact on biodiversity and local genetic pool

Impact of noise is still a subject of speculation due to

lack of data

Thomas Dahlgren

Perspectives

Integrated Ocean Monitoring

Network of continuous measurements

Cable-based observatories, drifters, Ferrybox, HF radars,

fixed moorings,

Dynamical baseline to account for accelerating

«natural changes» while increasing knowledge for

better sustainable management

From monitoring of targeted species to assessing

ecosystem functions and services

Assessing effects on the ecosystems as a whole

Published papers Shashkov, A., Dahlgren, T. G., Schlappy, M.-L., Rzhanov, Y. (2012). Usage of Video-mosaic

for Computer Aided Analysis of North Sea Hard Bottom Underwater Video for Baseline

Study of Offshore Windmill Park. Center for Coastal and Ocean Mapping, paper 685.

http://scholars.unh.edu/ccom/685.

Dahlgren, T. G., Schlappy, M.-L., Shashkov, A., Andersson, M. H., Rzhanov, Y., & Fer, I.

(2014). Assessing the Impact of Windfarms in Subtidal, Exposed Marine Areas. In

M. A. Shields & A. I. L. Payne (Eds.), Marine Renewable Energy Technology and

Environmental Interactions (pp. 39–48). Dordrecht: Springer Netherlands.

http://doi.org/10.1007/978-94-017-8002-5_4

Schlappy, M.-L., Shashkov, A., & Dahlgren, T. G. (2014). Comparison of manual and

semi-automatic underwater imagery analyses for monitoring of benthic hard-

bottom organisms at offshore renewable energy installations. Continental Shelf

Research, 83(C), 14–23. http://doi.org/10.1016/j.csr.2013.11.018

Shashkov, A., Dahlgren, T. G., Rzhanov, Y., & Schlappy, M.-L. (2015). Hydrobiologia,

756(1), 139–153. http://doi.org/10.1007/s10750-014-2072-5

Thanks