Cyanotypes of Dutch Algae

The story of making a photographically illustrated book that contains an overview of all species of Dutch algae through cyanotypes, in the spirit of Anna Atkins.

Ulva pertusa

Cyanotypes of Dutch Algae is a project by Pai Dekkers and Anne Leijdekkers. We are fascinated by algae and the cyanotype process and want to share our our discoveries in attempting to create a photographically illustrated book that contains all the species of Dutch algae. We want to explore the cyanotype process, question different approaches toward nature and show the mostly hidden algae lifeforms.

Photographs of British Algae

In 2017 the Rijksmuseum in Amsterdam acquired a copy of Anna Atkins' Photographs of British Algae: Cyanotype Impressions. The book was on display during the Rijksmuseum's exhibition on early photography New Realities. In the exhibition, one page of the book was on display with behind it a wall covered with facsimiles. Later, in 2018 Pai had the opportunity to view the entire book, leaving a permanent impression.

Anna Atkins at the Rijksmuseum

Text by Pai Dekkers

Blue pages with intricate images have haunted me from the moment I first encountered one of Anna Atkins' extraordinary books on British algae in the Rijksmuseum. Fascinated by her methods, I feel the need to comprehend her undertaking from a photographic perspective. Even though her approach is primarily a botanical one, the photographs she made from 1843-1853 are still incredibly beautiful today. I am, therefore, attempting to create a Dutch book on algae, in her spirit.

In the book Sun Gardens: Cyanotypes by Anna Atkins (2018), there is an overview of all the remaining copies. I learnt there are only seventeen known copies left, preserved by museums. Although preservation is necessary, this is problematic because the only time people are able to marvel at the photographs is during exhibitions. Needless to say these are quite rare. Even more problematic is the exhibiting of photography books, because you can only show one page at a time. Meaning, during a three-month exhibition the museum might only show three pages in total. Of course there are digital reproductions, but from my experience they do not even begin to compare to the original photographs. The physicality and detail of the prints are almost incomprehensible from a digital screen or offset printed book. It becomes even more impressive when you realise every page of the book is made by hand. There are estimates Mrs. Atkins must have produced over ten thousand prints during her life.

A page from the copy at the Rijksmuseum

A page from the copy at the Rijksmuseum

Mrs. Atkins did not only make books on algae. Together with her friend Anne Dixon she worked on Cyanotypes of British and Foreign Flowering Plants and Ferns. However beautiful, for me they do not quite utilize the quality of the cyanotype when used to produce a photogram. By placing the algae directly on the photographic paper, the transparency of the algae becomes visible in the finished print. Plants in general have thicker leaves that do not let light pass through them. This added dimension of transparency is why the impressions of algae intrigue me particularly. For the cyanotype process offered Mrs. Atkins in the nineteenth century, as it still offers us today, a new way of seeing.

12.03.2020 - 10:20AM - Strijenham

Low tide

Algae live a mostly hidden life underwater. This chapter sheds some light on the collecting of algae, in which the tides play a key role. In addition, I will share some of our experiences from excursions, and explain a little about intertidal zones.


Collecting Dutch Algae

I realised I have to create my own herbarium in order to produce the desired cyanotype impressions. This means going out into the field to collect specimens of algae. In order to do so, I reached out to several biologists. Luckily, they were happy to assist me collect and identify algae, as well as guide me during field trips. They have also helped me develop an understanding of all the different species of Dutch algae. Even with their information compiled, it is still not clear how many different species of algae I need to collect for a complete overview. My best guesses range from one hundred fifty to two hundred fifty, not considering algae invisible to the naked eye.


12.03.2020 - 10:28AM


But collecting algae is not a easy as you might think. You might have seen beach fronts covered with algae, but this is mostly dead algae of a singular species. In order to grow, algae needs to attach itself to a solid base, like plants they have something similar to roots. Therefore, they usually grow on rocks, pillars and even larger seashells. And this may seem obvious, but many species of algae are submerged most of the time. Meaning, it is not so simple collect them. One way to do this is by diving. Another is to wait for spring tide, a tide in which the difference between high and low tide is the greatest (see graphs below). This occurs twice a month, around the new and full moon.


During low tide, the algae that live in the intertidal zone lie dry. This period of a few hours, depending on the day and weather, allows you to collect algae without having to put on a wetsuit. However, you will need to wear boots to keep your feet dry. But why is the spring tide so important? There are three kinds of intertidal zones: low, mid and high. The high intertidal zone will lie dry during regular tidal activity and therefore for longer periods of time per day. Certain species are adapted to these dry and sunny conditions, allowing them to survive in this zone. A commonly found genus in this zone is Fucus. The mid intertidal zone is less frequently exposed to direct sunlight and periods of drought, providing room for a higher diversity in species. Since these conditions do not require sun and drought proof characteristics, it is easier for more species to survive. As you may have guessed, the spring tide is important to reach the low intertidal zone. During this period the zone only lies dry for an hour or so, depending on the wind strengs pushing the water toward or away from the land. So in order to reach the low growing algae you need almost perfect conditions. And because this zone is rarely exposed to direct sunlight and drought, there is another group of species adapted to these conditions.


The pool at Neeltje Jans will drain during low tide

These graphs of the tidal movement at Neeltje Jans in April 2020 show a difference from +205cm above NAP (Amsterdam Ordnance Datum) to -170cm below NAP around the appearance of the full moon. The lowest tides at Neeltje Jans in April occur on the 9th and 10th. On these dates around 10:30 AM the water will be -170cm below NAP.

Outgoing tide at Neeltje Jans, 10.04.2020

Pai at Neeltje Jans


Anne with a specimen of Sargassum muticum


Undaria pinnatifida



08.04.2020 - Strijenham

An introduction to phycology

Once collected, most specimens need to be examined closer under the microscope in order to determine the species. This chapter explains the study of algae on macro and micro levels and shows what to look for when identifying species.

Identifying Dutch Algae

During field trips it is impractical to bring along a microscope. Luckily, many species can be identified with our own eyes. Once you are familiar with the most common species it is possible to identify then without any visual aids. To start, here is an illustration which explains a little bit more about the biology of algae.

Ascophyllum nodosum

The three images below show different species of the genus Fucus. Someone who is familiar with algae can tell the first species is a Fucus vesiculosus, due to the paired air bladders. The second species can be identified a Fucus spiralis, since the branching occurs dichotomously and by the absence of air bladders. The third image shows a Fucus serratus, identifiable by the saw-edged branches.

Fucus vesiculosus

Fucus spiralis

Fucus serratus

When it comes to the genus Ulva, it is hard to differentiate between the species on a macroscopic level. They come in a wide variety of shapes and shades of green. However, it is possible to discern leaf-shaped Ulva known as Sea lettuce, from tube-shaped Ulva known as Gut weed. Sea lettuce, is recognisable by its broad flat sheets, bright green in colour. While Gut weed is composed of unbranched strands of tubes. Yet, Ulva pertusa is recognisable by its perforated leafs. These perforations are not the result of any damage but occur naturally in the thallus. A possible explanation is that it allows water to flow through it, so in heavy weather it is less likely to tear, allowing the plant to grow larger. There are specimen known up to 100cm large. But to be certain, you need a microscope in order to examine the organisation of cells, the chloroplasts and number of pyrenoids. 

Sea lettuce

(Ulva sp.)

Sea lettuce

Ulva pertusa

Gut weed

(Ulva intestinalis)

Sea lettuce

Ulva rigida

Ulva pertusa

Ulva rigida

Ulva pertusa,

image by Frank Perk

Cyanotypes of Dutch Algae

As stated, the aim of this project is to produce a cyanotype book that contains all species of Dutch algae, in the spirit of Anna Atkins. The collecting and identifying of algae is only the preliminary work in order to produce the required cyanotypes. Since it is not possible for us to create the complete overview in one go, the production and publication has been spread over multiple parts, on which I will expand here.

A letter to Mrs. Atkins

Cyantoypes of Dutch Algae: Part 1

Until now the collecting, drying and identifying all this algae has lead to the production of Cyanotypes of Dutch Algae: Part 1. This is only the first step in pursuing the production of a book that contains cyanotypes of all species of Dutch algae. Since the start of the project this pursuit has also raised many questions. For example, what does it mean to use the same approach toward nature as Mrs. Atkins did in the nineteenth century? For our ideas about nature have changed. Mainly, the notion that all living things have agency makes me question our approach. How can we justify collecting algae and using them for our own means of representation. Also, technology offers us new ways of seeing, making the cyanotype as a scientific document redundant. This reduces cyanotypes of algae to the aesthetic order. At the same time this is has value. The book can serve a an aesthetic representation of Dutch algae of this moment in time, worth preserving for future generations. In the last forty years alone the amount of foreign species has increased by twenty-five percent. And while the notion of time and national borders are cultural products, I think it is worth preserving a certain state of our natural environment, if only for future reference.

Finally, our findings may have value for the future. Perhaps we will find a way to represent our collected data and specimens through new ways of seeing. But for now we are working on Cyanotypes of Dutch Algae: Part 2. We still have a lot to learn about Dutch algae, Anna Aktins, John Herschel and our approach toward nature in general.

Hand bound by


©2020 by Dekkers Leijdekkers