Marine Intertidal Survey of Bridlington Slipway and Harbour Wall

 

MARINE INTERTIDAL

SURVEY OF

BRIDLINGTON SLIPWAY

AND HARBOUR WALL

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Report for East Riding Council

 

 

Table of Contents

EXECUTIVE SUMMARY

INTRODUCTION AND LITERATURE REVIEW

SITE DESCRIPTION AND OUTLINE OF METHODS

RESULTS

Sandstone Sea Wall

Smooth Concrete

Rough Concrete

Concrete Repairs on Sandstone Seawall

Granite Boulders

ENVIRONMENTAL INTERPRETATION

CONCLUSION

REFERENCES

 

 

 

This report details the main findings of an intertidal survey conducted over the autumn/early winter period in the vicinity of Bridlington Slipway and Harbour Wall as commissioned by East Riding Council prior to the implementation of hard coastal defences and the much needed improvement to slipway. The report outlines the three main sites of the area and the intertidal ecology found at each including species of commercial importance and conservation status. Overall, species diversity was greatest at the sandstone seawall supporting 24 different species. Only two species were noted to be of concern – The European Gull and the presence of marine worms on the sandy beach. However short-term disturbance does not have a major effect on populations and species distribution. Implementation of further sandstone structures alongside the ecological enhancement of existing coastal defences will increase species diversity and the complexity of intertidal assemblages, with reduced economic cost. Any construction should only take place in the Winter/Spring to reduce environmental and economic impacts.

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On behalf of East Riding Council (ERC) an intertidal survey of Bridlington Beach was conducted to assess the commercial importance and conservation status of species present prior to the implementation of hard coastal defences and improvement to slipway. This report outlines the findings of the intertidal survey and describes the methodologies performed, recordings of data collection and subsequent presentation of the findings and analysis. Recommendations as to what type of substrate to use for the new structures and any ecological enhancements that might help promote colonisation of new species to the area has also been included. In addition to the intertidal survey conducted on the harbour wall, slipway and granite defences; a shore walk over was also conducted. This was to determine the presence/absence of any key coastal terrestrial ecological elements alongside an examination of the sediment in order to determine evidence of macro-fauna. Evidence of any additional species in the area was also noted.

Three sites were selected for the intertidal survey as illustrated in Figure 1. These sites were chosen to ensure the survey included a range of substrata including natural bedrock, smooth and rough concrete and granite. All sites were surveyed to evaluate the composition of species at three tidal heights – Low, Mid and Upper where applicable. Surveys were conducted to determine if species had particular preference of substrata type and if this varied with abiotic and biotic factors experienced.

The sandstone seawall is the substrate closest to the natural bedrock where all three tidal heights were experienced. The concrete slipway is used by the general public to access the beach, this site only experienced the Mid and Upper tidal height range. The Granite Boulders at the ‘top’ of the beach only experienced the Upper tidal height range.

The surveys conducted were based upon the MNCR guidelines for in-situ intertidal biotopes using ACE survey methods (Hiscock, 2001) as specified in the JNCC Marine Monitoring Handbook (Davies et al, 2001). Data was converted into the SACFOR scale as devised by the Joint Nature Conservancy Council (JNNC) illustrated in Table 1 (Connor et al., 2004).

 

Figure 1: Map showing the survey area at Bridlington with each survey site highlighted.

Table 1: The SACFOR abundance scale and corresponding percentage cover / density per m2 of organisms as recommended for marine monitoring (JNCC MNCR guidelines). Where S = superabundant, A = abundant, C = common, F = Frequent, O = occasional and R = Rare.

% cover of species on shore

Corresponding SACFOR scale relating to % cover

Density of organisms in sediment / individual taxa on rocks

Corresponding SACFOR scale relating to density

40-79%

S

1000-9999 m2

S

20-39%

A

100-999 m2

A

10-19%

C

10-99 m2

C

5-9%

F

1-9 m2

F

1-5%

O

1-9 10m2

O

<1%

R

1-9 100m2

R

Sandstone Sea Wall

A total of 24 species were recorded at the sandstone survey site with species diversity highest at the low tidal height range illustrated in Table 2 and Table 3. Semibalanus balanoides were superabundant at this survey site. A number of rare species were also present including Porphyra Sp, Elminius modestus and Ceramium spwhich require specific biotic conditions.

Table 2: A table showing the species present at each tidal height on the sandstone sea wall including mean, standard deviation and SACFOR Scale for each. Where S = superabundant, A = abundant, C = common, F = Frequent, O = occasional and R = Rare. Species were counted within a m2 quadrat with species in green as % cover and species in yellow as individual counts.

Table 3: A table showing the species present/absent at the Sandstone Seawall site. Species highlighted green were present.

Figure 2: Image of m2 quadrat placed on sandstone seawall with key species present annotated.

Smooth Concrete

A total of 10 species were recorded at the smooth concrete survey site with species diversity the same at both tidal heights illustrated in Table 4 and Table 5. Percentage of bare rock was superabundant at this survey site. Fucus spiralis and Littorina saxtilis were only present at the upper tidal height. Mytilus edulis and Fucus vesiculosus was a lack of different species of algae present with reduced mollusc present also.

Table 4: A table showing the species present at each tidal height on the Smooth Concrete sea wall including mean, standard deviation and SACFOR Scale for each. Where S = superabundant, A = abundant, C = common, F = Frequent, O = occasional and R = Rare. Species data were counted within a m2 quadrat with species in green as % cover and species in yellow as individual counts.

Table 5: A table showing the species present/absent at the Smooth Seawall site. Species highlighted green were present.

 

Figure 3: Image of m2 quadrat placed on sandstone seawall with key species present annotated.

Rough Concrete

A total of 12 species were recorded at the rough concrete survey site with species diversity higher at the mid tidal height, illustrated in Table 6 and Table 7.  Ulva sp, Semibalanus balaoides and Patela vulgate were present at both tidal heights. Fucus spiralis, Porphyra, Littorina saxatilis were only present at the Upper tidal height. Ulva lactuca, Fucus vesiculosus. Littorina littorea and Nucella lapillus were only present at the mid tidal height.

Table 6: A table showing the species present at each tidal height on the Rough Concrete sea wall including mean, standard deviation and SACFOR Scale for each. Where S = superabundant, A = abundant, C = common, F = Frequent, O = occasional and R = Rare. Species data were counted within a m2 quadrat with species in green as % cover and species in yellow as individual counts.

 Species data were counted within a m2 quadrat with species in green as % cover and species in yellow as individual counts.

Table 7: A table showing the species present/absent at the Rough Concrete seawall site. Species highlighted green were present.

Figure 4: Image of m2 quadrat placed on sandstone seawall with key species present annotated.

Concrete Repairs on Sandstone Seawall

A total of 12 species were recorded at the concrete repairs survey site with species diversity highest at the low and mid tidal height, illustrated in Table 8 and Table 9. Semibalanus balanoides were superabundant at the low and mid tidal height with Mytilus edulis superabundant at the upper tidal height. Ulva lactuca and Fucus spiralis were only present at the low and mid tidal height.

Table 8: A table showing the species present at each tidal height on the Concrete Repairs on Sandstone Seawall including mean, standard deviation and SACFOR Scale for each. Where S = superabundant, A = abundant, C = common, F = Frequent, O = occasional and R = Rare. Species data were counted within a m2 quadrat with species in green as % cover and species in yellow as individual counts.

Table 9: A table showing the species present/absent at the Concrete Repairs survey site. Species highlighted green were present.

Granite Boulders

A total of 6 species were recorded at the granite survey site illustrated in Table 10 and Table 11. Bare rock was superabundant at this site with Fucus Spiralis in high abundance also. Mollusca species such as Littorina saxatili, Semibalanus balanoides and Austrominus modestus was present.

Table 10: A table showing the species present at each tidal height on the Granite Boulder including mean, standard deviation and SACFOR Scale for each. Species data were counted within a m2 quadrat with species in green as % cover and species in yellow as individual counts. Where S = superabundant, A = abundant, C = common, F = Frequent, O = occasional and R = Rare.

Table 11: A table showing the species present/absent at the Granite Boulder site. Species highlighted green were present.

 

Figure 5: Image of m2 quadrat placed on sandstone seawall with key species present annotated.

A coastal terrestrial ecology evaluation was performed to highlight the presence/absence of salt marshes and sand dune systems at Bridlington South Beach. As soft engineering solutions to managing the coastline (managed retreat), both of these ecological elements can provide coastal protection by acting as a resilient barrier absorbing the impact of high energy storms, wind and wave action (Hanley et al, 2014). However due to the topography of Bridlington and urbanisation of the sea front these strategies are not present and cannot be implemented at this site.

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Construction of coastal hard defences and improvement to the slipway may have consequences on the surrounding environment and businesses in Bridlington. During the summer months Bridlington is a popular tourist attraction, with its main source of income from beach-goers. Construction during this period would negatively affect the commercial business of the area therefore any development is to be avoided during this period.

Bridlington beach consists of medium-fine grain sized sand with no large cobbles or pebbles present. Wave ripples were witnessed along the beach (highlighted in Figure 6) suggesting that wind/wave action is strong enough to disperse the sand. Coastal defences transported via the sea will have a lower economic cost in comparison to transport via the land. This however may cause disturbance to species that reside/utilize the beach.

Figure 6: A photograph showing the ripples present on Bridington Beach.

During the survey, worm casts were noted (highlighted in Figure 7) suggesting polychaetes are present within the substrata; this was further confirmed by members of the public bait digging in the sand for marine worm species. These worms could be used for commercial use via the fishing industry or for individual recreational benefits.  Transportation of the hard coastal defences from the sea to the designated area alongside the construction needed to improve the slipway may inhibit the ability for individuals to collect worms from the sandy shore and affect species distribution within the substrata.

 

Figure 7: Photographs showing the worm castings present at Bridlington beach, highlighted in Figure B with Figure A showing a close-up with more detail. Figure C highlighting bait digging occurring on the beach.

Despite only one count, The European Herring Gull Larus argentatus was present on the sandy beach causing concern (highlighted in Figure 8). As a red listed species due to its large scale decline in numbers; the Herring Gull is a priority species on the UK Biodiversity Action Plan and is regarded as being Near Threatened in Europe (Lloyd et al, 2010). Disturbance to the sandy beach could negatively affect this species’ distribution. However studies suggest that disturbance by human activity can force foraging waders to seek alternative feeding grounds and that short term disturbance has not shown to have major long term effects on bird populations (Burton et al, 2002). A thorough bird survey of the area would need to be conducted to understand the interactions between bird species and the ecosystem fully, with a presence/absence table creates to highlight any protected species.

 

 

 

 

 

 

 

 

 

 

 

Figure 8: Photograph of the European Herring Gull Larus argentatus present on Bridlington beach.

 

Comparison of species present at each site illustrated that species diversity was greatest at the Sandstone Seawall site with a total of 24 species present, highlighted in Table 12.

Table 12: A table showing the comparison of species present/absent at each survey site conducted at Bridlington. Species highlighted green were present.

Differences in species composition between natural bedrock and artificial substrata have been attributed to the lack of key microhabitats, important for species residing in the intertidal zone (Browne and Chapman, 2011). Artificial structures lack surface heterogeneity and the ability to retain water at low tide contributing to reduced species abundance/diversity (Bulleri and Chapman, 2004). This is due to a lack of rock pools/crevices that provide refuge from both biotic and abiotic factors at all tidal heights that is commonly found in natural bedrock (Firth et al, 2013).

The sandstone seawall was the closest substrata to natural bedrock and therefore had the greatest biodiversity. As an ecosystem engineer, Semibalanus balanoides were in highest abundance at this site contributing to the biogenic build up and complexity of the habitat. By creating additional biological niches for other organisms, this species facilitate community succession and thus have positive impacts on species richness and abundance (Coombes et al, 2015) whilst providing bio-protection and reinforcing the structure itself (Risinger, 2012; Coombes et al, 2013).  Species diversity was lowest at the Granite Boulder site. Research by Ido and Shimrit (2015) highlight that concrete structures have high surface alkalinity and presence of compounds that are toxic to marine life, reducing intertidal assemblage diversity.

To improve species abundance and diversity to the area, adaptations can be made to coastal defence structures to encourage the colonisation and survival of intertidal species through ‘ecological enhancement’.  A study by Hall et al (2018) highlights the success of the addition of ‘Holes’ and ‘Grooves’ to granite rock armour increasing the species richness, diversity and abundance found on these artificial structures. ‘Holes’ drilled perpendicular into vertical surfaces of boulders retains water at low tide; with ‘Grooves’ aimed to replicate groove-microhabitat observed in natural rocky shores. Both implemented with minimal effort, these techniques can be executed without large plant machinery or high construction costs to existing granite boulders found at Bridlington increasing the biodiversity significantly with minimal disturbance to existing fauna and flora.

–          Differences in species composition between natural bedrock and artificial substrata have been attributed to the lack of key microhabitats, important for species residing in the intertidal zone that need refuge from abiotic and biotic factors.

–          The sandstone seawall had the greatest species diversity with 24 species present as this site is the closest substrata to the natural bedrock.

–          The granite boulders had the lowest species diversity with 6 species present, this is due to the high surface alkalinity and presence of compounds that are toxic to marine life reducing intertidal assemblage diversity.

–          Substrata that had high abundance of Semibalanus balanoides tended to have higher species diversity as acorn barnacles act as ecosystem engineers contributing to the biogenic build up and complexity of the habitat.

–          Adaptations can be made to coastal defence structures to encourage the colonisation and survival of intertidal species through ‘ecological enhancement’.  These include the addition of ‘Holes’ and ‘Grooves’.

–          Ecological enhancement can be executed without large plant machinery or high construction costs to existing coastal defences with minimal disturbance to existing fauna and flora.

–          The European Gull and marine worms were the only species present that are of conservation/commercial concern. However short-term disturbance does not have a major effect on populations and species distribution.

–          Any construction should only take place in the Winter/Spring to reduce environmental and economic impacts.

–          A thorough bird survey of the area would needs to be taken to understand the interactions between species and ecosystem fully.

Browne, M. and Chapman, M. (2011). Ecologically Informed Engineering Reduces Loss of Intertidal Biodiversity on Artificial Shorelines. Environmental Science & Technology, 45(19), pp.8204-8207.

Bulleri, F. and Chapman, M. (2004). Intertidal assemblages on artificial and natural habitats in marinas on the north-west coast of Italy. Marine Biology, 145(2).

Burton, N., Rehfisch, M. and Clark, N. (2002). Impacts of Disturbance from Construction Work on the Densities and Feeding Behavior of Waterbirds Using the Intertidal Mudflats of Cardiff Bay, UK. Environmental Management, 30(6), pp.865-871.

Connor, D., Allen, J., Golding, N., Howell, K., Lieberknecht, L., Northern, K. and Reker, J. (2004). The Marine Habitat Classification For Britain And Ireland Version 04.05. Peterborough: Joint Nature Conservation Committee.

Coombes, M., La Marca, E., Naylor, L. and Thompson, R. (2015). Getting into the groove: Opportunities to enhance the ecological value of hard coastal infrastructure using fine-scale surface textures. Ecological Engineering, 77, pp.314-323.

Coombes, M., Naylor, L., Viles, H. and Thompson, R. (2013). Bioprotection and disturbance: Seaweed, microclimatic stability and conditions for mechanical weathering in the intertidal zone. Geomorphology, 202, pp.4-14.

Davies, J., Baxter, J., Bradley, M., Connor, D., Khan, J., Murray, E., Sanderson, W., Turnbull, C. & Vincent, M., (2001), Marine Monitoring Handbook, 405 pp, ISBN 1 85716 550 0

Firth, L., Thompson, R., White, F., Schofield, M., Skov, M., Hoggart, S., Jackson, J., Knights, A. and Hawkins, S. (2013). The importance of water-retaining features for biodiversity on artificial intertidal coastal defence structures. Diversity and Distributions, 19(10), pp.1275-1283.

Hall, A., Herbert, R., Britton, J. and Hull, S. (2018). Ecological enhancement techniques to improve habitat heterogeneity on coastal defence structures. Estuarine, Coastal and Shelf Science, 210, pp.68-78.

Hanley, M., Hoggart, S., Simmonds, D., Bichot, A., Colangelo, M., Bozzeda, F., Heurtefeux, H., Ondiviela, B., Ostrowski, R., Recio, M., Trude, R., Zawadzka-Kahlau, E. and Thompson, R. (2014). Shifting sands? Coastal protection by sand banks, beaches and dunes. Coastal Engineering, 87, pp.136-146.

Hiscock, K.  (2001). Procedural Guideline No. 32.  In situ survey of intertidal biotopes using abundance scales and checklists at exact locations (ACE surveys).  In Davies, J. et al., (2001), Marine Monitoring Handbook, 405 pp, ISBN 1 85716 550 0

Ido, S. and Shimrit, P. (2015). Blue is the new green – Ecological enhancement of concrete based coastal and marine infrastructure. Ecological Engineering, 84, pp.260-272.

Lloyd, C., Tasker, M. and Partridge, K. (2010). The Status of Seabirds in Britain and Ireland. London: A & C Black.

Risinger, J. (2012). Biologically dominated engineered coastal breakwaters. PhD. Louisiana State University and Agricultural and Mechanical College.