Gene banks not just for fish

There are gene banks ( germplasm repositories, or germplasm repositories), which collect resources of plants and animals important to either the economy or nature conservation. After the ecological disaster in the Oder River in the summer of 2022, the Olsztyn-based Institute of Inland Fisheries-State Research Institute named after the author of the report. Stanislaw Sakovich has begun work on establishing a gene bank for native fish from the affected basin. It is intended to provide important support for stocking with ecotypes/genetic lines native to, or at least typical of, the river. It will accumulate both spawners and sperm stored at ultra-low temperatures. In addition, refugia (refugia) will be designated in the river basin itself, i.e. places where aquatic organisms could take refuge (either on their own or with the help of people) in the event of a renewed threat. However, fish are not the only organisms requiring support after a disaster.

Hurry up slowly! Good preparation is half the battle

Scientists, anglers and fishermen stress that restoration of entire ecosystems is necessary before stocking can proceed. Spawning habitat restoration remains particularly important for all ecophysiological groups of Oder fish and vertebrates (lithophiles rubbing on rocks; phytophiles requiring underwater meadows of pondweed or trichinella, sometimes also spring flooding of meadows and pastures; ostracophiles needing live mussels as incubators for eggs). It is also necessary to restore populations of aquatic invertebrates, which provide a food base for fish and serve as indicators of water quality. This raises the question of whether gene banks should be established for aquatic organisms other than fish.

Better to have and not use than to need and not have

Some organisms are inherently resistant to “golden algae” toxins, but habitat loss, climate change, alien species invasions, or overexploitation of wild populations (including untargeted ones such as bycatch) harm everyone. It’s worth planning gene banks now for groups of plants, animals and microorganisms crucial to Oder’s ecosystems and the local economy.

Gene banks for macrophytes

Macrophytes (formerly also seaweeds) in Poland are called all plants and self-living protists discernible to the naked eye, often used to assess water status under the Water Framework Directive. Such a heterogeneous group, including both vascular plants, bryophytes and macroscopic algae (stoneworts), and sometimes a number of filamentous green algae, requires the use of a variety of techniques to preserve their living gene resources for many years. Most of them, of course, can be raised in aquariums and aquaterraria. Deposition of generative diasporas and in vitro cultures can be problematic.

What do you mean! someone asks. After all, you hear so much about lotus seeds being able to grow after spending hundreds or even thousands of years in dried-up sediments. Yes, but they are journalistic ducks. Among the angiosperms of aquatic plants, there is no shortage of species with seeds abundant in fats and proteins, so they are not very resistant to severe drying or freezing. This type of seed in conservation storage is referred to as recalcitrant (recalcitrant – “resistant, wayward”). Their textbook examples are precisely the seeds of our “water lilies”: water lilies, water lilies, water lilies and water lilies. They are sensitive to overdrying and below a certain threshold level of moisture they lose their viability.

Nevertheless, Polish botanical gardens, within the framework of the project “Population assessment and ex situ protection of selected wild species of rare and endangered plants in Poland – FlorNaturROBiA“, have banished seeds of several species of emergent macrophytes and helophytes, including. Dagger’s nematode Schoenoplectus lacustris, peat swamp Scheuchzeria palustris, brown hellebore Rhynchospora fusca, and alpine woolly adelgid Baethryon alpinum, and even one species with floating leaves – the subalpine pondweed Potamogeton polygonifolius. They have turned out to be the so-called “”new” products. orthodox, or diasporas endure very severe drying and sometimes even freezing after desiccation.

Water ferns have been cultivated for centuries for ornamental purposes, to aerate waters or as spawning grounds for aquarium fish. The team of prof. J. Rybczynski and A. Mikula of the Botanical Garden – Center for the Preservation of Biological Diversity of the Polish Academy of Sciences developed the world’s first cryopreservation methods for spores and gametophytes of various herbaceous and woody ferns [1]. So maybe their aquatic cousins, like knobbed and salvinia, will also live to see such procedures. Worse is the case of the porblin, an aquatic forkbeard.

Mosses and liverworts – poikilohydric plants, i.e. plants that endure very severe desiccation – seem particularly predestined for long-term deposition in gene banks. It has been known for at least a dozen years that spores collected in winter, or heavily dried herbarium material (but younger than 7 years), can germinate, producing viable tangles [2, 3]. Only recently, a novel method of protecting the oospores of bracken was developed in Poznan, using sodium alginate. Alginate with a concentration of 2-3 percent. with the algae’s ambient water, antibiotics and fungicides forms microcapsules around Charophyta oospores. Such microcapsules can be used not only to enhance sparse natural populations and create replacement habitats for these rare, sometimes legally protected algae, but also to observe germination phases during laboratory experiments and student exercises [4].

Gene banks for aquatic macroinvertebrates

There is a belief among many conservationists that the restoration of natural conditions is enough for extinct local species to return to the ecosystem by the forces of nature itself. American observations of the return of rare mussel species to rivers after blooms of “killer algae” do not allow for such optimism! In the restoration of freshwater invertebrates, it is worth drawing on the experience of, admittedly few, but successful restorations of charismatic macroinvertebrate species: the river pearl mussel Margaritifera margaritifera (in Poland, more recently, also the thick-shelled scoter Unio crassus, and in the United States the oyster mussel Epioblasma capsaeformis), native river crayfish Astacus astacus and mudskippers Pontastacus leptodactylus, long-tailed mayflies Palingenia longicauda, certain forkbeards Plecopter and dragonflies.

The low – compared to fish, birds and mammals – participation of freshwater macroinvertebrates in restoration programs is related to several issues, including:

• underestimation of the ecosystem services they provide, especially their role as indicators, regulators and as food for vertebrates;
• overly optimistic assessment of their abundance in recent natural sites and their (re)colonization capacity;
• the need for prior or simultaneous restoration of entire habitats, including plant communities or natural bedforms;
• lack of gene banks, so lack of both conservation collections and procedures for collecting gene resources of different life stages, estimating genetic diversity, multiplying, transporting and reincorporating into historical or replacement sites;
• too low, for the needs of reintroduction, in the existing ex situ conservation collections [5, 6].

For many invertebrate groups, we know literally nothing about the long-term storage potential of their in vitro cultures, eggs, larvae, gemmules, stolons or mature individuals. The vibrant development of aquariums and aquacultures allows for moderate optimism. Since in the last few decades we have learned to breed in conditions as close to natural as possible and efficiently reproduce more groups of marine invertebrates, among others. sponges, corals, starfish, snakeheads, polychaetes, horsetails, snails, etc., then perhaps there is hope for their more inconspicuous freshwater relatives as well.

Developing a method for freezing invertebrates may be the key to success in preserving them:

• in vitro cultures;
• survival stages naturally adapted to survive the winter;
• gametes, eggs, zygotes, embryos and larvae even of those species that never come into contact with frost.

The latter procedures will be difficult to develop for molds with large, yolk-rich (polycytic) oocytes and embryos. After all, we still can’t apply them to dragonflies, fish and amphibians! It is easier for fish to change their sex than to ban their eggs and zygotes [7].

Conservation breeding of parasitic species can be problematic, at least at certain stages of their ontogeny. To some extent, gene banks have managed this in the case of pearl mussels and some skinks, keeping them together with the right fish species – their hosts. Parasitologists have been perfecting in vitro breeding of flukes and tapeworms for decades, and agrobiologists of nematodes, used for biological control of crop pests. Maybe it’s time to think about conservation breeding of a few dying bugs?

For the time being, it is necessary to create collections of adult and juvenile specimens in conditions as close to natural as possible, primarily close to the sites of their actual locations. As an additional reserve, however, there is no harm in multiplying collections by creating conservation herds in countries free from the risk of natural disasters, wars and civil unrest. After all, this has been done for more than a century for vascular plants, birds and mammals in zoos, such as those in Wroclaw and Warsaw, for species of Tajikistan in PAN OB CZRB or endemics of the Caucasus in Geopark Kielce.

A long road to Noah’s Ark for Oder

Gene banks are an ancient dream of mankind, almost as old as agriculture itself. The biblical Noah took a pair of land animals each on the ark. His Akkadian predecessor Utnapishtim also took plants on board. The Persian Jamshid, on the other hand, hid the most beautiful-smelling herbs and the most nutritious vegetables in an underground shelter for the three-year winter that wiped out all previous life on Earth.

Last year’s bloom of P. parvum in the Oder River reminded everyone of the need for such facilities. However, it is worth remembering that gene banks are not as productive as classical banks. Rare species cannot simply be “created out of nothing” with a few clicks, like funds in an electronic account, or even added to, like banknotes at the mint. It is easier for us to create multiple derivatives than to store the germ plasm of multiple groups of organisms without losing its viability and without introducing secondary mutations.

The general principles of creating replacement populations are common to all organisms. To do this, it is necessary to select the best-preserved habitat or restore it, providing or restoring processes crucial to the restored taxon, and to select specimens with optimal genotypes and phenotypes, paying attention to the provenance and evolutionary past of the genetic line/ecotype in question. Efforts should also be made to ensure that pathogens or invasive alien species are not unknowingly transferred along with the reconstituted target species. Polish scientists and activists have unique experience in Europe and the world in the long-term collection of macrophyte gene resources. They also have a growing incentive to do pioneering work in conservation breeding of many groups of invertebrates, fish and amphibians previously overlooked in the activities of zoos and gene banks. Nothing but action!

Let’s hope that the Odessa Noah’s Ark will be built before another equally terrible disaster occurs!

In the article, I used, among others. From the works:

1. Mikula A., Rybczynski J.J. (2006). Cryopreservation as a tool for long-term storage of cells, tissues and organs derived from in vitro cultures. Biotechnology 4(75): 145-163. https://rcin.org.pl/Content/87236/POZN271_113739_biotechnologia-2006-no4-mikula.pdf
2. Rodrigo M.A. (2021). Wetland restoration with hydrophytes: A review. Plants, 10(6), 1035.
3. Sabovljević M., Vujičić M., Pantović J., Sabovljević A. (2014). Bryophyte conservation biology: In vitro approach to the ex situ conservation of bryophytes from Europe. Plant Biosystems-An International Journal Dealing with all Aspects of Plant Biology, 148(4), 857-868.
4. Rybak A.S. (2021). Microencapsulation with the usage of sodium alginate: A promising method for preserving stonewort (Characeae, Charophyta) oospores to support laboratory and field experiments. Algal Research, 54, 102236.
5. Jourdan J., Plath M., Tonkin J.D., Ceylan M., Dumeier A.C., Gellert G., …, Haase P. (2019). Reintroduction of freshwater macroinvertebrates: challenges and opportunities. Biological Reviews, 94(2), 368-387.
6. Lim S.H., Do Y. (2023). Macroinvertebrate conservation in river ecosystems: Challenges, restoration strategies, and integrated management approaches. Entomological Research, 53(8), 271-290.
7. Liu Y., Blackburn H., Taylor S.S., Tiersch T.R. (2019). Development of germplasm repositories to assist conservation of endangered fishes: Examples from small-bodied livebearing fishes. Theriogenology, 135, 138-151.