Driving innovation in wood protection for the marine environment
Submitting InstitutionUniversity of Portsmouth
Unit of AssessmentEarth Systems and Environmental Sciences
Summary Impact TypeEnvironmental
Research Subject Area(s)
Mathematical Sciences: Statistics
Environmental Sciences: Environmental Science and Management
Biological Sciences: Genetics
Summary of the impact
Marine wood borers cause huge economic losses by damaging maritime
structures. Research conducted by Cragg's team has driven the move from
broad-spectrum, environmentally-hazardous wood protection methods towards
environmentally-benign approaches tailored to target specific organisms.
Their novel testing methods have accelerated evaluation of protection
methods while reducing testing costs (impact 1). Their evaluations have
been used to inform guidelines for selection of timbers for waterside
construction issued by the UK Environment Agency (impact 2) and to market
less well-known timber species (impact 3). Their information on invasive
borers affects local and global decision making (impact 4).
Research on the biodegradation of wood in the sea has been pursued at
Portsmouth for over 40 years. In 1997, Dr S. Cragg (Reader in Zoology)
joined the biodeterioration team, initially working with Dr. R. Eaton
(Reader in Biodeterioration, University of Portsmouth 1970-2008). Since
2006, Cragg has led a team of Portsmouth-based researchers in this area to
develop internationally-recognised expertise in the identification,
biology and husbandry of marine wood borers.
At Portsmouth, Cragg developed quantitative methods for assessing the
vulnerability of wood to crustacean wood-borer activity by measuring
faecal pellet production rate. Method development involved research on the
role of wood surface hardness in conferring resistance to Limnoria
attack (1), resulting in the inclusion of a denser,
non-durable wood species in routine testing, and the optimisation of
environmental and animal-related conditions for the use of L.
quadripunctata as a test organism (2). This protocol
provided the first standardised laboratory test for the rapid and
consistent assessment of the resistance of timbers to attack by Limnoria
spp. It was used by the Portsmouth team to evaluate over 60 species of
hardwoods from Ghana, Guyana, Guyane, Brazil, South Africa and Europe (3)
and to assess a number of alternative wood preservation methods, including
epoxy resin treatment, treatment with furfuryl alcohol (furfurylation) and
chemical modification (4). Researchers at Portsmouth, under
the direction of Cragg, developed an abrasion testing protocol which
yielded performance data that complemented the borer resistance
measurements. A protocol to test effects of furfurylation on settlement
and growth of another category of marine wood borer (shipworm) was
developed which demonstrated that furfurylation prevents shipworm growth.
The work on marine borers at Portsmouth, and, in particular, the benefits
of the protocol, prompted an invitation in 2013 for Cragg to join
Technical Committee 38 of the European Standards Commission (CEN) charged
with revision of current standards for testing resistance to
biodegradation (BS EN 350-1 and 2: 1994). Cragg is giving guidance
on predicting performance of wood in the sea for the provisional standard,
The research expertise of the Portsmouth team in the ecology and
biogeography of wood borers has been used to link laboratory performance
data with field assessments, and to predict borer hazard in different
areas of the world. The team has demonstrated the importance of life
history strategies in borer infestation (5) and the
potential of tropical species to arrive in the Mediterranean from the
Caribbean and the Red Sea (5, 6). One key crustacean wood-borer, L.
quadripunctata, was found by Cragg to be invasive, with the
potential to spread to further temperate areas (CABI, 2011;
Section 4 Source 10). A wood boring bivalve at the Mary Rose wreck
site in the Solent was identified by Cragg as a species whose range was
expanding northwards, with subsequent implications for conservation of
this unique artefact. Another key bivalve borer species was shown to
actually be two cryptic species (6), meaning that studies
with this nominal species need to be re-evaluated.
References to the research
UoP contributors in bold;
1. Cragg, S.M., Danjon, C., Mansfield-Williams, H.D. (2007)
Contribution of hardness to the natural resistance of a range of wood
species to attack by the marine borer Limnoria. Holzforschung
61:201-206. DOI: 10.1515/HF.2007.035
IF 2.42, 2nd out of 22 in Materials Science, Paper and Wood.
2. Borges, L. M. S., Cragg, S. M., Busch S. (2009) A
laboratory assay for measuring feeding and mortality of the marine
wood-borer Limnoria under forced feeding conditions: a basis for a
standard test method. Int. Biodeterioration and Biodegradation. 63:
289-296. DOI: 10.1016/j.ibiod.2008.10.007
IF 2.06 87th out of 210 in Environmental Science.
3. Borges, L. M. S., Cragg, S. M., Bergot, J., Williams, J. R., Shayler,
B. and Sawyer, G. S. (2008) Laboratory screening of tropical
hardwoods for natural resistance to the marine borer Limnoria
quadripunctata with an investigation of the role of leachable and
non-leachable factors. Holzforschung 62: 99-111. DOI: 10.1515/HF.2008.015
IF 2.42, 2nd out of 22 in Materials Science, Paper and Wood. REF2 output:
4. Papadopoulos, A. N., Duquesnoy, P., Cragg, S. M. and Pitman,
A. J. (2008). The resistance of wood modified with linear chain carboxylic
acid anhydrides to attack by the marine wood borer Limnoria
quadripunctata Holthius. Int. Biodet. Biodeg. 61: 199-202. DOI:
IF 2.06 87th out of 210 in Environmental Science.
5. Cragg, S. M., Jumel, M-C., Al-Horani, F. A. and Hendy, I.
W. (2009) The life history characteristics of the wood-boring
bivalve Teredo bartschi are suited to the elevated salinity,
oligotrophic circulation in the Gulf of Aqaba, Red Sea. J. Exp. Mar. Biol.
Ecol. 375: 99-105. DOI: 10.1016/j.jembe.2009.05.014 IF 2.26 27th out of
100 in Marine and Freshwater Biology.
6. Borges, L. M. S., Sivrikaya, H., le Roux, C. A., Shipway,
J. R., Cragg, S. M., Costa, F. O. (2012) Investigating the
taxonomy and systematics of marine wood borers (Bivalvia: Teredinidae)
combining evidence from morphology, DNA barcodes and nuclear locus
sequences. Invert. Systemat. 26: 572-582. DOI: 10.1071/IS12028
IF 1.98 31st out of 151 in Zoology.
References 1, 3 and 5 should be used to assess the quality of the
Details of the impact
Degradation of wood by marine wood boring species causes major economic
losses world-wide. For example, over £400K was spent recently to remedy
damage by marine borers to Yarmouth Pier, Isle of Wight, while in Seattle,
repairs of $290M have been required due to borer damage to timbers in the
seawall. Traditional wood preservatives, such as chromated copper
arsenate, are prohibited in Europe (Commission Directive 2003/2/EC) for
use in marine construction due to risks to aquatic organisms, and
established construction timbers, such as greenheart and ekki, are a
diminishing resource. Lesser-utilised species (LUS) and novel treatments
therefore need to be evaluated for their suitability in the marine
Impact 1. Acceleration of evaluation of protection methods while
reducing testing costs
The European standard for marine testing of natural durability of wood
and the protective value of wood treatments (BS EN 275) requires the
exposure and annual inspection of wooden panels in situ for five years.
The cost of maintaining each field testing site can be as high as €12K
p.a. (S3) and generation of results is slow. Standard rapid
laboratory screening methods were previously available for testing
resistance to fungi and wood boring insects, but not to marine wood
Cragg's team developed a novel laboratory protocol that quantifies
resistance to marine wood borers in naturally durable timbers and timbers
with protective treatments. This method has been validated against in situ
testing (S1) and confers the ability to perform rapid,
statistically-robust evaluations, reducing both the duration and the cost
of testing. In 2008, the Timber Research and Development Association
(TRADA), with Portsmouth, used this method to expand their portfolio of
marine timber testing, generating over £200,000 additional income from
contracts with the Forestry Commission of Ghana, the Guyana Forestry
Commission and the Environment Agency (S2). Similarly, the method
has been used to assess the efficacy of alternative timber modifications
on behalf of commercial companies (Kebony ASA, Norway) and to perform
rapid iterative evaluation of furfurylation methods on behalf of
governmental organisations (Technical Research Institute, Sweden) (S3).
The suite of methods developed at Portsmouth underpins a current,
extensive evaluation programme of novel wood-polymer composites for use in
marine construction by a Scandinavian consortium of government and
commercial timber organisations.
Impact 2. Evidence of durability backs EA procurement policy
In 2009, the Environment Agency (EA) and TRADA jointly commissioned
Portsmouth researchers to examine the performance of 18 LUS tropical
hardwoods, benchmarked against greenheart and ekki. This enabled TRADA to
make specific recommendations to its members on specific LUS species as
suitable alternatives to greenheart (S1) and the EA to publish
(2011) authoritative guidance aimed at structural and civil engineers,
design consultants, building contractors, asset managers and procurement
professionals (S4). Subsequently, the EA has changed its
procurement procedures to include a mandatory requirement to consider LUS
and to follow the methodology within the EA guidance. It has also set up a
framework contract with two UK-based LUS timber suppliers (this contract
is also open to other government agencies and public sector bodies) and
has used LUS in a range of freshwater and marine applications that have
delivered cost savings and sustained performance (S5).
Impact 3. Evaluations have been used to market less well-known timber
species Evaluations of the resistance to borer attack of Guyanese timbers
conducted at Portsmouth indicated that several LUS performed as well as
traditional marine construction species. This information was incorporated
into recommendations by TRADA to the Guyana Forestry Commission (GFC) on
ten timbers for longer-term marine testing (S6), and was included
in a series of datasheets and booklets on relevant tropical timbers
prepared by the GFC (S7). The International Tropical Timber
Organisation (ITTO) included these studies and recommendations in guidance
and training material delivered to over 80 forestry concession holders,
saw millers, lumber yard holders, exporters, and other stakeholders in the
three major counties of Guyana (S8).
Impact 4. Information on borer hazard changes affects decision-making
locally and globally
In 2006, Cragg detected living specimens of destructive warm-water borers
in timbers remaining at the wreck site of the Mary Rose ship. As a result,
the Mary Rose Trust immediately introduced a number of physical methods of
protection against borer attack at the site and initiated an enhanced
programme of monitoring (S9). Cragg has provided all information
and text for the borer, L. quadripunctata in the Invasive Species
Compendium developed by the international, intergovernmental Centre for
Agriculture and Biosciences International (CABI). The Compendium is an
authoritative database that supports decision-making in the management of
invasive species worldwide (S10).
Sources to corroborate the impact
Assessment of the durability and engineering properties of
lesser-known hardwood timber species for use in marine and freshwater
construction TRADA Technology Ltd Report (2010). TRADA
recommendations on LUS species as suitable alternatives to greenheart.
- Letter, Senior Technical Consultant, TRADA, confirming that novel
testing methodology enabled TRADA to diversify its portfolio of testing
projects, generating >£200K of additional contract income since 2008.
- Letter, Research Manager, SP Traetek, confirming that novel testing
methodology allowed rapid iterative testing and evaluation of
furfurylation methods for protection of wood.
Delivering Benefits through Evidence Series `Alternative hardwood
timbers for use in marine and fresh water construction' Project:
SC070083/R1 DEFRA Environment Agency (2011). Environment
Agency/DEFRA encourages the specification and use of lesser used species
of hardwood timber in marine and freshwater construction.
- Letter, Sustainable Procurement Advisor, Environment Agency,
confirming that UoP research underpins the EA's policy of diversifying
the range of timbers used for marine and freshwater construction.
Assessment of the resistance of 15 lesser used timbers from Guyana
to abrasion and attack by Limnoria quadripunctata Holthuis. Report
TC/F07096 Part 2 prepared for the Guyana Forestry Commission. TRADA
Technology Ltd (2008). 10 species of timbers recommended to the Guyanan
Forestry Commission for longer-term marine testing.
- Promotional material for Guyanan timbers with marine borer resistance
- International Tropical Timber Organisation Report (034405) on training
and information campaign in Guyana disseminating findings contained in
- Letter, Head of Conservation, Mary Rose Trust, confirming that Cragg's
research directly influenced conservation practices at the wreck site
- CABI, (2011). Limnoria quadripunctata [original text by S. M.
Cragg]. In: Invasive Species Compendium. Wallingford, UK: CAB
Demonstrates world-wide invasiveness of L. quadripunctata