Scrape sampling biofouling from artificial structures like marinas. (Sampling method images)

Marine sampling
Scrape sampling biofouling
- photographing specimens, a parasitic copepod found in some sea squirts, tunicates, Notodelphys cf. caerulea? 1

Notes for above -

These notes refer to a sampling method that has been adopted for my local marina, where the pontoons have a concrete face. Where marinas have a PVC / rubber face, material must be collected by hand or strong net to prevent damage to the marina. The form of sampling has been developed for the ergonomic retrieval of specimens from a sample, and the photography of retrieved specimens. The latter a vital consideration if specimens are to be sent for sequencing or if fixing for identification / verification by an expert.

Equipment Used
1 Large, deep bucket.
Air / watertight plastic food storage containers. e.g. 210mm x 140mm x 100mm.
1 x 500mm Heavy Duty Scraper with 50mm head.
1 x 250mm rectangular fine mesh aquarium net on 1200mm pole.
Small air / watertight plastic food storage containers for larger samples e.g. larger worms.
Small storage containers / dishes to store and observe specimens at home.
3ml Disposable plastic pipettes
Spoon and titanium tweezers
Underwater torch
Magnifying head gear
Stereomicroscope
Camera
Fridge
A supply of surplus seawater e.g. for filtering for photography.

A Heavy Duty Scraper is a vital piece of equipment. A wallpaper scraper can be used but these are too short to be useful, more down force is needed, they have less reach, and there is a sure risk of damage to knuckles. A Heavy Duty Scraper of size above will adequately do the job without too much force, and without risk of damage to marina pontoons. Tip, search ebay for Heavy Duty Scraper.

Food storage containers. The interior sides of the food containers used should be roughened using wire wool or fine sandpaper before use. This is to enable any animal, coming out of the sample material / sediment, to climb, and maintain a grip on the side of the vessel. Smooth plastic is less easy to cling to and thus specimens may fall off the sides of the container on moving it from a fridge. At marinas, containers are 3/4 filled with fresh seawater before sample is placed into the container from the small sieve.

A large, fine mesh, aquarium net is used to collect scrapings and is positioned directly under the scraper to catch material. Because of the +/- neutral buoyancy of material being scraped off, and local currents, it is often necessary to sweep the net up towards the surface of the water at the end of the scrape to catch material. Any further material in the water can then be caught in the net before the net is emptied into the large bucket with fitted sieve. Being careful to make sure that the net is free of material by washing it in the sample water before using it again. One has to remember the majority of species might be difficult to see in the field, so a clean net between scrapes is essential. Each containers is no more than 20% full of sieved material and to prevent it becoming anoxic too soon.

Once the containers have been filled with sieved material and seawater, the lids of the containers are fixed on two sides, side and bottom, then containers are placed one by one in a bucket of seawater, container lids slightly opened to expel all air still in the container, the container will then be completely full of seawater before sealing. This is to prevent sloshing during transport and damage to life in the container. The downside is that the contents will start to degrade without air, so specimen containers need to be quickly transported back to where they are being looked at. The other downside is air temperature, as summer temperatures will quickly heat seawater. In this instance, seawater replacement within containers should be undertaken prior to leaving the site, to decrease temperature and add fresh aerated seawater. Ideally in summer containers should be transported in a cool box or 12v camping fridge unless you live locally.

On arrival at home or office, excess seawater is released from the container, with scrapings are evenly spread around the container, then containers are then chilled straight away as colder water holds more oxygen. The excess seawater can be collected, filtered through three sheets of kitchen roll, chilled and used for the photography of specimens. The water level should be approx.10mm from the top of the container to try and avoid spillage on putting the container in a fridge.

After allowing scrapings to settle and being chilled for 10-15 minutes, containers are checked. It'll soon be clear what to expect from the samples as the fauna is quite active at this time, and a 15 minute dark, cooling period helps bring out worms and nudibranchs, flatworms etc.. Anything from 6 - 60 worms might be expected at this time. Specimens found early on are usually active worms, worms such as Platynereis. It'll be found that different species appear at different times, in terms of length of storage / degree of anoxia.

Specimen containers can then be placed back in the fridge if they need to chill further or kept out to warm slightly. There are no hard fast rules for the method, the procedure involves changing environmental conditions of the sample container using dark, shade and bright light, with temperature change and varying oxygen levels. N.B. Varying conditions is highly important for getting as much living material out of the sample as possible.

Specimens are taken from the container using 3ml disposable plastic pipettes, if a wider aperture is needed the end of the pipette can be cut with scissors to widen it. Similarly if the specimen to be extracted is large, then a plastic tea or desert spoon is used to avoid damage, or titanium tweezers can be used on more solid objects e.g. tube worms, titanium tweezers because they do not rust, stainless steel is useless with seawater. Once containers have been inspected and specimens removed, specimens are then looked at under a stereomicroscope to identify species. Common species can be sorted from more unusual ones. Any necessary photography is done at this stage because of colour fading of stored specimens.

Once the first batch has been looked at, it is time for a quick coffee before checking the containers again and repeating the process, remembering to change the environmental conditions each time. BUT containers should not be left out at room temperature for too long as this will cause the water to become quickly anoxic and if it does, everything dies and rots at an incredible pace. The specimen containers should be checked as regularly as possible within the first 12 hours, most species are found during this time, but can be left as long as 24 hours.

A standard fridge is used but small 12v / 240v camping fridges are useful for chilling samples. The ideal temperature is a few degrees either side of current sea temperature. Chilling in a standard fridge will however extend the life of the sample. Damaged sea squirts and sponges rot very quickly are the main cause of oxygen depletion so should be removed. Specimens that are extracted from the sample can be chilled and returned to where they were found after study (unless they are a non-native species), a small battery aerator is good for keeping specimens alive and can also be used in a fridge with the sample. Material left in the container once it has become anoxic should be composted and not returned to the sea, and to prevent the spread of invasive non-native species.

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APHOTOMARINE supports open source data recording and sharing for the benefit of wildlife, recorders, research, science and education. The project recommends the following websites and works with the following bodies and organisations.

The Marine Biological Association or MBA, based in Plymouth, is one of the world’s longest-running societies dedicated to promoting research into our oceans and the life they support. Since 1884 the MBA has been providing a unified, clear, independent voice on behalf of the marine biological community.It has a growing membership in over 40 countries.

The National Biodiversity Network or NBN is a charity that supports open source data sharing and recording supporting conservation, science and education. "Why do recorders need open source?". Simply because it supports the core values of wildlife recording and the free use of records and data over a very wide network that includes partners like the Natural History Museum.

The taxonomy used here is based on that of the following database, which is also used by the MBA, NHM and the NBN.

The World Register of Marine Species or WoRMS.

APHOTOMARINE

An online educational resource dedicated to the photography of marine themes, marinelife, life on the seashore and in rockpools in the coastal waters of south-West England by David Fenwick.

An online educational resource dedicated to the photography of
marine themes, marinelife, life on the seashore and in rockpools
in the coastal waters of south-West England by David Fenwick.