Author: Ibon Cancio, UPV/EHU Associated Professor in Cell Biology; researcher in the ‘Cell Biology & Environmental Toxicology’ (CBET) research group of the Plentzia Marine Station (PiE-UPV/EHU); Spanish scientific representative in the EMBRC Committee of Nodes

Some scientific endeavours require a lot of effort, dedication and knowledge but also a pinch of faith. This was surely the case for Alister Hardy, who deeply believed in plankton and Darwin, but also God. Sir Hardy’s important religious character, the last crusade in his academic career after retiring from science, is not necessarily of interest to us as scientists. His Robin Hood-like dedication to plankton research, however, is quite a different matter.

Alister Hardy was born in Nottingham in 1896, in the same county where Robin Hood lived. Interested in nature, he initiated his university studies in Oxford. However, World War I started, and Hardy was commissioned into a Cyclist Battalion (I did not know that there had been such a thing!). Here he served as a camouflage officer, a job well-suited to a marine zoologist with artistic interests. He returned to Oxford in 1919 to take Honours in zoology, a course where he would meet Sylvia Garstang. She was the daughter of Walter Garstang, eminent researcher and Professor of Zoology at the University of Leeds who had established the Robin Hood’s Bay Marine Laboratory in 1912. This meeting between a young boy of Nottingham and the daughter of a Robin Hood’s Bay man would have lifelong implications for Hardy, and for Sylvia as well.

Portrait of Alister Hardy
Sir Alister Clavering Hardy by Walter Bird
bromide print, 1966. NPG x38371. ©National Portrait Gallery, London

During his studies, Hardy obtained a scholarship for a research proposal on Priapulus. If you do not know what these marine invertebrates are, have a look, but bear in mind that they are called 'penis worms'. While finishing his studies, he won a 'Naples table', a six-month research stay at Stazione Zoologica Anton Dhorn (SZN). At SZN, he worked on sipunculids (look for these worms as well!) but became interested in plankton research. Upon his return from Naples, he graduated in 1921 and immediately joined the staff of the Fisheries Laboratory in Lowestoft, whose first director had ben Garstang himself.

As a young, newly-graduated scientist, he was assigned to study the diet of herring from young to adult stages, analysing their daily plankton intake. This basically was done by analysing gut content and sampling the sea through towing nets, made of fine silk like that used to sieve flour in mills. Hardy noticed that when plankton tows were replicated in a given sampling station at different times or depths, the variation observed among replicates was greater than that observed when comparing two distant stations. In effect, trying to obtain meaningful conclusions on plankton abundance and variability over a wide geographical area by sampling at a given point at a given moment was like taking a photograph of the mid-day sun, and when looking at the picture, pretending that there should be bright light at midnight. Plankton surveys required approaches providing a continuous record.

Hardy was then made chief zoologist of the RRS Discovery expedition to the Southern Ocean and the Antarctic that took place between 1925 and 1927. The expedition was organised by the Discovery Committee in London on behalf of the British Colonial Office. Its mission was to conduct biological, ecological and oceanographic research to better understand whale population dynamics, and improve the regulation of the southern whaling industry that operated from South Georgia, British overseas territory. In advance, during 1924, Hardy was co-responsible for different pre-exploration arrangements. This included planning for the construction of a marine station close to the whaling base of Grytviken in South Georgia, Discovery House, where the land-based investigations would be carried out during the expedition.

Image of book
Hardy’s 1926 water-colour entitled 'Bloody waters' as published in 'Great Waters', picturing the whaling station at Grytviken in South Georgia, where Antarctic explorer Ernest Shackleton is buried. (Photograph by Ibon Cancio)

They were going to study the diet of commercially exploited whales and whale-marking activities were on the menu. Johan Hjort was also developing his own whale-mark shooting methods in Norway. So Hjort invited Hardy, as a member of the Discovery Committee, aboard the Michael Sars to test and compare their devices on whales around Faroe and Iceland. One of the tools devised by the Committee, and that Hardy tried on board, aimed at avoiding the noise of guns that could disturb a whale if a first shot failed and a second would be needed. It was a crossbow 'with a string of steel wire drawn back by a jack against two powerful springs' but it was unsuccessful in comparison to the guns of Hjort and the Committee itself. As Hardy reported, 'it could not be brought into action quickly enough' (Robin Hood knew that bows were faster than crossbows).

Great Waters book cover
Hardy's book 'Great Waters' showing one of his watercolours picturing RRS Discovery. (Photograph by Ibon Cancio)

Hardy published his investigations during the expedition in the 'Discovery Reports' series and 40 years later in the lovely illustrated book 'Great Waters' (1967), a classic very suitable for your holidays this summer. Read it! Hardy focused his Discovery studies on zooplankton surveys. They consisted of vertical and horizontal trawls with a total of 1071 plankton samples collected, accompanied of physicochemical measurements, of temperature, salinity, O2 and phosphate content... I do not know whether faith moves mountains, but krill moves whales. He discovered that krill was mainly composed of one species Euphausia superba and its distribution was closely correlated to that of blue and fin whales. Instead, phytoplankton abundance was inversely correlated to that of krill, and therefore to that of whales. He also described the vertical migrations of plankton, more or less marked depending on the species in the krill. During the expedition, he designed a device that was to be called the Continuous Plankton Recorder (CPR), and that has become a legend in ocean ecological research. The CPR towed behind a ship, and as the ship sails forward, the CPR collects plankton samples and stores them on a moving band of silk, fixing them in an aldehyde mixture that allows conservation and later examination in the lab. The CPR was towed 35 times during the Discovery expedition.

Krill drawing
Krill in the Southern Ocean as drawn by Hardy and published in 'Great Waters', with its dominant species Euphausia superba. (Photograph by Ibon Cancio)

Hardy, on his return from the Southern Ocean, became the first professor of zoology at the University of Hull (1928). Hull thus became the hub receiving the samples of East-Anglian fishing vessels towing CPRs during their regular voyages in the North Sea and the Atlantic Ocean. This was the birth of the CPR survey, officially established in 1931. Then, in 1942, Hardy was appointed professor of natural history at the University of Aberdeen (and Edinburgh became the home of the CPR survey), to become Linacre Professor of Zoology at the University of Oxford from 1946 to 1963.

CPR results were published first in the Journal of Marine Biological Association and then in its own dedicated journal, Hull Bulletins of Marine Ecology. Hardy published data showing a positive correlation in the distribution of the copepod Calanus fimmarchicus and herrings, underlining a 18,3% increased likelihood of catching herring while fishing in waters rich in Calanus. Correlations were negative if fishing in waters rich in phytoplankton. Hardy published two oceanographic books covering his post-Antarctic research as a marine biologist in the North Sea and the north Atlantic Ocean: 'The open sea: the world of plankton' (1956) and 'The open sea II: fish and fisheries' (1959). Hardy, the 'Prince of the plankton thieves', obtained royal recognition when made Fellow of the Royal Society, and was subsequently knighted in 1957.

Image of plankton net and plankton
A plankton net ready to be towed in the North Sea during the BECPELAG project on board the FRS Scotia in 2001 and our plentiful plankton (krill) harvest. Very tasty when eaten raw! (Photographs by Ibon Cancio)

The CPR Survey still runs today, using a network of commercial ships that includes ferries and cargo ships, without any meaningful modifications in its sample collection protocol since 1958. That year the survey was extended to the US, Canada and Greenland. It constitutes the longest running and most extensive (Guinness record holding) marine ecological survey in the world. It is coordinated by the Sir Alister Hardy Foundation for Ocean Sciences (SAHFOS) with support from different nations and organisations, including the Intergovernmental Oceanographic Commission, and it analyses global plankton distribution and abundance. As of 22 May 2021 (36 years after the day of Hardy’s death) approximately 8.5 million miles have been towed and 7 million of them have been sampled (Earth's polar circumference is nearly 21,600 nautical miles). Plankton is an excellent indicator of environmental change and by historically monitoring its communities across maritime regions, the CPR has built an enormous database used by researchers. Additionally, the learning outcomes provided can be applied by policymakers for regulatory actions in fisheries management, biodiversity assessment, and climate change, ocean acidification or environmental and human health monitoring.

Picture of survey results
Image showing the sampling effort of the CPR Survey in 2014 as obtained from their web page in March 2020 ( ©2019 - Marine Biological Association of the UK

To close, the last paragraph of 'Great Waters' based on Hardy’s experiences during the Discovery voyage reveals the nature of some science people in those times. Remember that Hardy and Sylvia Garstang met in 1919. Then, Hardy left for his different scientific crusades. First was a trip to Naples, then the exploration of the herring banks in the Atlantic, the whale-marking trip on the Michael Sars, and finally, a two-year voyage to explore the Southern Ocean, so Hardy closed his book with this passage:

’I might perhaps have dwelt upon our feelings as we approached home after being two years away, but I was too excited, and perhaps too nervous! Sylvia, daughter of (now the late) Professor Walter Garstang, and I had almost got engaged just before I sailed; and then we finally decided by cable, or was it wireless, to announce the event half-way through the voyage. We had expected to sail into Falmouth Bay on the afternoon of 29th September. Mrs Kemp and Sylvia had come to meet us, and were watching from the cliffs; a change of wind, however, delayed us and robbed them of the sight of our sails appearing over the horizon - it was dark before we got in. I shall never forget the excitement of dropping anchor, going ashore with Kemp in the ship ’s boat, and meeting my wife to be for the first time since we were actually engaged-meeting her on the steps of the quay on a dark and windy night. For me it was a fitting end to one voyage and the beginning of another’.

Alister Hardy and Sylvia Garstang married immediately (December 1927) after Hardy’s return to the UK (29 September 1927) and lived a long life, hopefully like the one of Robin and Lady Marian. He died in Oxford on 22 May 1985 and she would follow him in October of that very same year. Hardy’s legacy, the CPR survey now housed at Plymouth MBA, survives both of them, enduring the volatility of long-term science programme funding!

Caricature of Hardy dancing
Hardy as seen by one of his colleagues on board of the RRS Discovery and included by himself in his Great Waters. It is good to demystify researchers and knighted Sirs. (Photograph by Ibon Cancio)

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