Heysham Flats Sabellaria aveolata Report 2011
Aims
1. To investigate the size and health of Sabellaria aveolata reefs Heysham Flats.
2. To produce a method to assess and record these finding which can be used as a baseline
data set that can be repeated easily in the future by another person.
3. Present these finds to the relevant organisations.
Introduction
Background Information
 Taxonomy – Annelida (Segmented worm), Polychaeta (Bristleworm), Sabelleria, alveolata.
 Structure – Thorax with 3 pairs of flattened chaetal sheaths, inner and middle rows of
opercula chaetae with asymmetrically angular spines pointing distally and transversely
respectively.
 Life span is typically 3-5 years but can live up to 9.
 When growing apertures of the tubes are sharply defined which are lost in the erosion stage.
 In the first two years area manly covered by reef, but after they are colonised by other
species (seaweeds, molluscs, fish).
 Older reefs increase biodiversity in an area which would normally be sand abraded rocks and
boulders. They can restrict drainage and create small pools.
 Lower part of rocky seashore as they need a rock substrate to build on.
 Do not penetrate into low salinities.
 Need sufficient water movement with plenty of suspended sand in the water for tube/reef
building.
 Larvae drift, they can settle anywhere but are strongly stimulated to settle where Sabelleria
alveolata are or have existed.
 These reefs can provide habitats for many other species.
 They live close together, their tubes forming sheets or reefs in a honeycomb pattern, up to
7m across and 1m thick.
 Reefs show a cyclical pattern of growth, erosion and re-growth.
 Each worm measures 3cm – 4cm in length and is a suspension feeder trapping plankton in its
tentacles.
 Tubes can be 20cm in length, and 5mm wide, can be built in 12cm per year.
Location
 Most abundant on the south and west coast and found around Ireland, the Northern limit is
the Outer Hebrides.
 Most numerous areas are between Duddon Estuary and Dubmill Point on the Solway Firth,
occurs on 5 SSSIs in Cumbria.
 On wave exposed shores (Selker Point, Walney) the reefs are 20cm – 30cm tall.
 Where there is more stability and less scouring(Tarn Bay) the reefs are more domed up to
50cm tall.
 At Dubmill Point there are small colonies on larger bounders.
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At St Bees Head the reefs develop on vertical rock faces up to 2m off the ground, showing
the height of sand suspended in the tide.
Threats
 Vulnerable to storm damage and extreme cold.
 Reefs may die back for several years.
 Changes in sediment regime - can become buried by sand due to sea defences, beach
replenishment (can survive being buried for weeks), can also cause the reefs to form where
they were not previously present.
 Physical damage - mainly trampling from humans fishermen and bait diggers especially, reef
can recover from light single trampling.
 Aquaculture – mussel cultivation cause the reefs to become covered in faeces and
pseudofaeces, mussels also settle on the reef and as they grow they break the lubes open.
 Pollution/Chemical contaminants – they are some reports that S.alveolata disappearing are
due to pollution but there is very little evidence for this.
 Cooling water discharge – at Hinkley Point found growth was higher in the winter due to
water outflow which was 8 -10oC warmer than control site.
 Colonisation by other species.
Methodology
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Preliminary visit to Heysham Flats at extreme low water on the spring tides, this is to ensure
that the most amount of the reef is mapped use a GPS to walk around and track a route.
After the initial mapping has been done a 50m by 50m grid of waypoints will be produced of
the Heysham Flat Scar area on GIS.
These waypoints will then be loaded on to the GPS.
To survey the site it will be visited at low water on a spring tide. A 0.5m2 quadrat will be
places at each of the waypoints on the reef.
At each waypoint the percentage coverage of Sabellaria aveolata, mussels (adult and 2011
seed), mussel mud, shell, sand, back rock, cobble and algae. There will also be a section for
pool for when there is too much water above the substratum. There will also be a Sabellaria
aveolata assessment which will look at the formation (patchy, hummock, sheet and reef)
and heath of the reef. The heath of the reef will be look at whether the reef is dead or alive
and whether the apertures are crisp, worn or newly settled with very small apertures. Please
see attached sheet for guidance on the different classifications.
Equipment List
 GPS Gamin Etrex Venture
 Waders
 Lifejacket
 Quadrat
 Tape Measure
 Camera
 Measuring Rule
Results
Preliminary Visit 16/06/11 Low Water 19.02 1.4m Tide
Figure 1. Results of Heysham Flat Sabellaria survey.
Left Map – Total areas mapped including waypoints of healthy sites of Sabellaria and waypoints of
lowest point reached. Top Right Map – Overview of Heysham Flat and Sabellaria Eroded Reef.
Bottom Right Map - Main areas of healthy patchy Sabellaria tubes
Areas A-F were old, eroded areas of sabellaria incorporated within them are patches of mussel and
dead shell.
Table 1: Areas of dead eroded Sabellaria
Area Name
A
B
C
D
E
F
Total
Total Area m2
131
63
50
13120
5827
2990
22181
Table 2: Large Areas of Alive Sabellaria
Area Name
1
2
Total
Total Area m2
53.99
24.14
78.13
Table 3: Time and Location of Low Water Waypoints
Low Water Waypoint
1
2
3
4
5
Time at Waypoint
18.10
18.14
18.58
18.39
18.17
Observations Made on Areas and Waypoints during the Survey.
Waypoint 1 – Rock Present with small patches of healthy worm tubes several patches were of roughly
fewer than 10cm in diameter.
Waypoint 2 – Small areas of healthy tubes, diameter of 10cm.
Waypoint 3 – Figure 1. An area with healthy Sabellaria present. Small patches present.
Figure 1. Alive Sabellaria Tubes
Waypoint 5 – 5 patches confirmed as alive within this area.
Waypoint 7 – There was present a patch of what looked to be still healthy tubes of the Sabellaria with
areas of remaining old reef which was heavily eroded.
Area of Sabellaria
Heavily Eroded Sabellaria Reef
Area D – This area was heavily eroded, though areas still were high above the skear bed. Present were
areas of shell and in some places mussels were growing.
Large areas of intact dead reef – (Yellow bar 1m)
Overview of Area D from eastern edge
Area D on water line Southern Side
Waypoint 12 and 13 – These areas had more extensive coverage with patches of healthy reef
Free standing patch of Sabellaria
Freestanding Patch of Healthy Tubes
New Settlement of Sabellaria (Scale in cm)
Area E and F – Were more heavily eroded patches of Sabellaria with a greater percentage of dead
shell coverage.
Potential area of healthy Sabellaria Waypoint 15
Erosion on Area E
Erosion on the western edge of Area E
Overview of the preliminary survey was that there were large areas of eroded reef with small patches
of a live Sabellaria tube with some newly settled patches.
Surveys Carried Out On The 30/08/11 Low Water 19.32 0.8m Tide And The 27/09/11 Low
Water 18.24 0.8m Tide
Figure 2. Map Showing The Percentage Cover Of Sabellaria aveolata At Each Of The Survey Stations
From this map it can be seen where the higher percentages of Sabellaria aveolata, it can be seen
that the areas of higher density is on the South West area of the Skear with a dense patches on the
North of the Skear with less dense patches scattered over the rest of the reef. This is similar to the
original assessment.
Reef on the South Side
Reef on the North Side
Other small patch of reef on the Skear
Figure 3. Map Showing The Percentage Of The Different Types Of Formations At Each Survey Station
From this map it can be seen the different types of formations which gives an idea of the age of the
reef. A patchy formation would suggest that there has not been a large amount of growth and a
small amount of Sabellaria aveolata has settled in that area. A hummock suggests an older
formation which has a greater amount of settlement and growth as it is a bigger structure. A sheet is
a larger formation that covers a large area but is often not very thick whereas a reef covers a large
area and is thicker which is usually older than a sheet. A sheet suggests a large settlement which has
developed into a reef. A reef can also consist of lots of hummocks which have merged to produce a
reef. Most of the Skear consists of patchy formations which from the original assessment would be
correct as it consisted of mainly dead reef so the formation would be younger in age. The large
formation of hummocks and reef were found on the South side and North side which coincides with
the areas which have the greatest percentage cover.
Large Formations
Small Formations
Figure 4. Map Showing The Percentage Of The Different Health Categories At Each Survey Station
From this map it can be seen the health of the reef. Dead reef indicates reef in bad health that has
died off. Worn apertures indicates that the reef has been exposed to undesirable conditions as there
has not been any new growth. Crisp apertures indicate that the reef is in good health and there has
been new growth and favourable conditions. Newly settled reef also indicates good health as there
is a new population to replace older reef. From the preliminary survey it showed that a large
proportion of the reef was dead but looking at the secondary assessment later in the year there was
much more alive and newly settled reef. The majority of the new settled reef and crisp apertures
were found on the South and North side of the Skear.
Overview Of The Reef
Looking at the reef as a whole and taking into account all of the maps and data above it is clear that
between the date of the preliminary 16/06/2011 and secondary survey 30/08/2011 27/09/2011
there was a large amount of growth and settlement.
Photos of Reef 16/06/2011
Photos of Reef 30/08/2011
Photos of Reef 27/09/2011
This shows that the reef has an ability to regenerate itself over a short period of three months when
the conditions are favourable. Going from a reef mainly consisting of dead Sabellaria aveolata which
is heavily eroded with a few patches of a live tubes, to a reef that consist of large areas of a live
Sabellaria aveolata with newly settle populations in large formations. This transformation is either
due to heavily eroded reef regenerating or settlement from the original small areas of healthy reef.
Future Monitoring
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To resurvey the site in early 2012 to see if the winter conditions (cold rough seas) effects the
reef and turns the Skear back into large areas of dead and heavily eroded Sabellaria
aveolata.
Resurvey in future years and take into account the mussel population has on the size of reef.
If funding was found to do genetic tests of the population of Sabellaria aveolata to see if the
newly settled colony was the offspring of the original population or to find out if it was new
settlement from a different geographical population.