Aim:
The aim of this project 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 largely 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.
Content:
Collection of data will involve field work where fish abundance
and diversity are quantified using underwater GoPro cameras positioned on the
sea bed. Camera deployment will include 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)
Atlantic herring (Clupea harengus) utilize
cobble reefs for spawning and that 2) artificial cobble reefs may facilitate
Atlantic herring spawning activities. Because Atlantic herring is an important
prey species for many larger species, cobble reefs may 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. These data are
collected using automatic listening stations that record sounds produced by harbour
porpoise.
Duration:
Data collection will take 1 - 2 months. Data analysis and write-up are
expected to take 2 - 3 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 will be combined with data
collected after the artificial reefs are established. Project duration can be adjusted to match student requirements.
I samarbejde med
http://alsstenrev.dk/
Forudsætninger
Interest in marine biology and data analyses