ISO 21716-2:2020

INTERNATIONAL ISO
STANDARD 21716-2
First edition
2020-11
Ships and marine technology —
Bioassay methods for screening anti-
fouling paints —
Part 2:
Barnacles
Reference number
©
ISO 2020
© ISO 2020
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ii © ISO 2020 – All rights reserved

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 2
5 Material and apparatus . 3
6 Preparation of the test organism and the test seawater . 4
6.1 General . 4
6.2 Preparation of the test organism . 4
6.3 Preparation of the test seawater . 4
7 Preparation of the triangular prisms. 4
7.1 General . 4
7.2 Preparation of the test panels and control panels . 4
7.3 Assembly of the triangular prisms . 4
8 Operation of the test . 6
8.1 Cyprid viability test . 6
8.2 Bioassay . 7
9 Validation of the test .10
9.1 General .10
9.2 Requirements of the cyprids viability test .10
9.3 Requirements of the bioassay .11
10 Settlement rates .12
10.1 General .12
10.2 Calculation of the settlement rate for the test panel .12
10.3 Data treatment and interpretation of the results.12
11 Test report .13
Annex A (informative) Statistical analysis — Examples .15
Annex B (informative) The barnacle Amphibalanus amphitrite .18
Annex C (informative) Life cycle of a barnacle .21
Annex D (informative) Materials .23
Annex E (informative) Identification of adult Amphibalanus amphitrite .24
Bibliography .26
Foreword
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This document was prepared by Technical Committee ISO/TC 8, Ships and marine technology,
Subcommittee SC 2, Marine environment protection, in collaboration with Technical Committee
ISO/TC 35, Paints and varnishes, Subcommittee SC 9, General test methods for paints and varnishes.
A list of all parts in the ISO 21716 series can be found on the ISO website.
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iv © ISO 2020 – All rights reserved

Introduction
Anti-fouling paints that contain biocides are widely used to prevent fouling of ship hulls by marine
organisms. Effective anti-fouling technologies are critical to maintaining the fuel consumption efficiency
of ships and also for minimizing possible translocation of aquatic species through maritime trade. The
evaluation of anti-fouling paints is generally undertaken by adopting a tiered approach whereby paint
manufacturers use a battery of laboratory, raft, patch tests and full vessel trials. Raft, patch tests and
full vessel trials are generally conducted over extended periods of time and are predominantly relied
upon for the prediction of coating performance when used commercially on in-service ships.
The results of raft, patch test and full vessel trials (field testing) can be used as part of the regulatory
process for pesticidal or biocidal products in certain countries in order to demonstrate the efficacy
of an anti-fouling paint. Laboratory testing alone is recognized as being unable to predict in-service
performance or efficacy. For example, guidance published by the European Chemicals Agency (ECHA)
on the assessment and evaluation of efficacy for anti-fouling products states clearly that laboratory
testing of individual anti-fouling paints is not undertaken as it is not considered to be a realistic
evaluation of the product; field testing, which permits anti-fouling products to be tested under similar
operating conditions and stresses as those encountered when the anti-fouling products are in service is
routinely undertaken instead (see Reference [28]).
Whilst laboratory tests are unable to reliably predict in-service coating performance, they have merit
in the screening of experimental coatings for further evaluation during the research and development
process.
Reproducible objective data obtained by following standardized screening methods, independent of
the test location or the season, can be a useful tool to support the selection of anti-fouling paints for
higher tier testing, e.g. raft or ship tests. ISO 21716 provides a compilation and description of in vitro
bioassay methods intended to aid the process of screening anti-fouling paints prior to higher tier raft
or ship tests. Toxicological screening methods included in each part of ISO 21716 can be used for such
purposes as early decision-making in research and product development, rapid feedback on potential
toxicological concerns, or for the preliminary assessment of anti-fouling paints. For instance, ISO 21716
provides information on methods that can be used to screen anti-fouling paints in order to determine
whether to continue development of an experimental paint and/or a product that contains a particular
ingredient, or to determine whether to take on the cost of performing the remaining tiers within a
complete tiered-testing strategy.
ISO 21716 provides screening bioassays related to certain common genera of fouling organisms, namely
barnacles, mussels and algae. These screening tests are relatively simple and rapid laboratory tests
that can be performed to provide an indication of the toxicity of a painted surface towards selected
test organisms. The screening tests described in each part of ISO 21716 can be used as part of a tiered
approach to predict the ability of an anti-fouling paint to prevent fouling on ships. Alternatively, to
prevent the translocation of invasive marine species by progressively involving subsequent semi-field
(e.g. raft panels) and field testing (e.g. ship trials). On their own, the screening tests described in each
part of ISO 21716 do not reliably predict the ability of an anti-fouling paint to prevent fouling on ships
or the translocation of invasive marine species.
ISO 21716 is not intended to provide a list of validated tests for testing the efficacy of anti-fouling
paints; this can be covered in regulations. It is not intended to provide a list of validated tests for this
purpose, nor for predicting the ability of a fouling control paint to prevent fouling on ships or to prevent
the translocation of invasive marine species.
Barnacles are typical marine sessile organisms regarded as harmful fouling organisms because of
their impact on fuel consumption and the potential for translocation of non-indigenous species if they
become attached to ship hulls.
This test method utilizes cyprid juveniles to assess settling behaviour in the presence of treated panels.
Cyprid larvae are considered the most relevant life stage for such evaluations as it is at this point that
the barnacle settles on appropriate substrate prior to metamorphosis into the adult. More information
is provided in Annexes B and C.
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