18 Somerset Street,
Private Bag 1015
Grahamstown, 6140
Tel: 046 622 9899
Cell: 083 383 9228
Fax: 046 622 9371
ant@saeon.ac.za
Over what spatial scales do habitat and invertebrate
community correlate with the fish community from remote
underwater stereo-video systems
Project summary
Within the concepts of ecosystem based management (EBM) and ecosystem based
fisheries management (EBFM) there is a requirement to understand the relationships within
and between the fish and invertebrate communities, and the abiotic environmental drivers.
In benthic habitats, habitat type, structure and depth are recognised as key determinants of
the associated fish and invertebrate communities, and there is evidence to suggest that
characteristics of the invertebrate community can be related to the fish community
Often the fish community is the focus of research and monitoring, and the surveys of the
habitat types and sessile and mobile invertebrate communities are not prioritised. Financial
and time constraints are often the main factors resulting in this bias. For example, detailed
habitat mapping is a very costly endeavour (i.e. with multi-beam echo sounders and
sidescan sonars), and is not a financially viable option for most research institutes. Also,
monitoring invertebrate communities is typically conducted with photo-quadrates. These
surveys are normally conducted independently from fish community assessments, resulting
in greater field time requirements and higher project expenses. There are however some
novel techniques (i.e. baited and unbaited remote underwater stereo-video systems =
stereo-B/RUVs) that allow comprehensive assessments of the fish community together with
snapshot assessments of the habitat and invertebrate community.
While this method provides a solution, it is uncertain whether sufficient information is
captured in the snapshot view to relate patterns to the fish community. This is particularly
true for the stereo-BRUVs which attract fish into the survey area from a well beyond the
visible area.
It is thus the aim of this project to investigate the relationship between fish community
structure sampled with stereo-B/RUVs and the invertebrate community structure over
increasing distances (meters) away from the position where the fish community was
recorded.
Research Questions
Part 1: The relationship between habitat, sessile invertebrates and fish
If stereo-RUV can be considered to be a mostly unbiased method to sample fish
assemblages:
1. What is the optimum survey spatial coverage of habitat and sessile invertebrates in
order to understand their relationship with fish communities measured with stereoRUVs at the scale of the sample site.
2. Based on the above results, what is the relationship between habitat, sessile
invertebrates and fish community at the scale of the sample site.
Part 2: The effect of bait
If there is a relationship between habitat, sessile invertebrate and fish communities, how
does the effect of bait alter:
1. The optimal survey spatial coverage for habitat and sessile invertebrates in order to
understand their relationship with fish communities measured with stereo-BRUVs at
the scale of the sample site.
2. Based on the above results, what is the relationship between habitat, sessile
invertebrates and fish community at the scale of the sample site and how does this
differ between stereo-BRUVs and stereo-RUVs samples.
Research approach
STUDY SITES
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Rheeders Reef complex in the Tsitsikamma National Park (NP) marine protected
area (MPA)
This project will set out to investigate whether or not relationships between the
habitat, sessile invertebrates and fish community can be detected using stereoB/RUVs and photo-quadrates collected in the vicinity of the fish samples. As such
only one study site will be targeted to ensure spatial variation does not dilute the
relationships, if present. In addition, by focussing the research in an old and
established MPA, the fish and invertebrate communities will be undisturbed providing
an ideal location to identify the relationships.
SAMPLING DESIGN
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The sampling will be based on a repeated measures field experiment.
Stratification: The study area will be stratified by depth (shallow = 10-15m; deep =
16-30m) and reef profile (high; low). Within each combination of the stratification
criteria six sites will be targeted (Total number of sites = 2 depths x 2 profiles x 6
replicates = 24 sites)
Fish community: At each site the fish community will be sampled first with the stereoRUVs and subsequently with the stereo-BRUVs (Total video samples = 48 video
samples).
Habitat: At each site a 40 x 40m sampling block will be targeted, with the fish
sampling site in the centre. Within each block, 65 photo-quadrates will be captured
using a Jump Camera. The distribution of the photo-quadrates will be systematic
with 5m between adjacent photos, with one centre photo-quadrate at the site of the
fish sample (Total photo-quadrates = 1560). The habitat and sessile invertebrate
community in the vicinity of the fish sample will then be classified at 0, 25m2, 36m2,
64m2 based on the results from the pooled photo-quadrates.
Timeframe
1.
2.
3.
4.
Data collection: February – April 2014
Video and photo analysis: May – September 2014
Data analysis: October – February 2015
Write up: March – December 2015
Manpower
1.
2.
3.
4.
Dr Anthony Bernard (first supervisor)
Dr Albrecht Götz (co-supervisor)
(Dr) Elodie Heyns (co-supervisor)
Fulltime MSc
Material
1.
2.
3.
4.
5.
6.
Superduck Honkenii (8m) with capstan winch
Boat fuel and oil (~500l)
Four stereo-B/RUVs
Pilchard bait (~50kg)
Jump Camera
External hard-drives (2 x 3 terabyte)
Expected outcomes
1.
2.
3.
4.
One MSc student
Two papers published in peer reviewed journals
One conference abstract
Training and education material
Budget:
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Running costs carried by guaranteed SAEON Elwandle

MSc student bursary to be sourced from Rhodes University, NRF and SAEON.
Availability and amount will depend on the merit of the applicant and cannot be
guaranteed.
Application
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Interested students can apply directly to SAEON Elwandle:
046 622 9899; Ant or Ali: ant@saeon.ac.za and/or albrecht@saeon.ac.za
Please include a CV and short motivation.