Effects of reefs on fish abundance and diversity -- implications for marine fisheries and conservation of harbour porpoises

Aim:

The aim of this study is to examine to what extent cobble reefs affect abundance and diversity of fish and harbour porpoises (Phocoena phocoena) in coastal areas. The project will reveal if cobble reefs benefit marine fisheries and conservation of harbour porpoise.

Background:

Cobble is extracted in coastal areas in Denmark, but the effects of the extraction on fish abundance and diversity are unknown. While many coastal fish populations have been in decline in recent years, the possible relationship between cobble extraction and declining fish populations remains uncertain. Using underwater video footage, this project examines fish abundance and diversity on natural cobble reefs, artificial cobble reefs and on sandy sea beds. Project videos are available here and here. The project is carried out in the bay Sønderborg Bugt. Related papers are available here, here and here.

Content:

Fish abundance and diversity will be quantified using video footage available from underwater GoPro cameras positioned on the sea bed. Camera deployments involve both baited and unbaited cameras. Data collection will cover three types of areas: 1) control areas with sandy sea beds, 2) areas with natural cobble reefs, and 3) areas with artificial cobble reefs. The study design will be based on the Before-After-Control-Impact (BACI) approach. Specifically, the study will test the hypotheses that 1) reef restoration has led to an increase in fish abundance and diversity, and 2) artificial cobble reefs may facilitate Atlantic herring spawning activities. Because Atlantic herring is an important prey species for many larger species, cobble reefs are expected to support several trophic levels in the marine environment. In addition to the underwater video recording, abundance of harbour porpoise is measured in the three study areas (1-3). These data are collected using automatic listening stations that record sounds produced by harbour porpoise.  

Duration:

Video analyses of the available footage will take 1-4 months. Statistical analysis will take 1-4 months, and write-up is expected to take another 2-4 months. Baseline data (i.e. without artificial reefs established) have already been collected, and the student will have access to those data. The baseline data can be combined with data collected after the artificial reefs were established.

 

Contact:

Jon C. Svendsen: 

Email: jos@aqua.dtu.dk

Phone: 00 45 93 51 16 63

Twitter: @JonCSvendsen

 

I samarbejde med

http://alsstenrev.dk/

Forudsætninger

Interest in marine biology and data analyses

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