By Sheila Byers, MLSS Director-at-Large
Marine Life Sanctuaries Society of BC (MLSS) at www.mlssbc.com
People, for the most part, tend to celebrate the wonders of the ocean because of the diversity of seafood that are harvested and brought to our table to enjoy. Seafood, e.g., fishes, crabs, prawns, shrimp, clams, is delicious and healthy for us to eat. When it comes to sponges living on the seafloor, however, generally not a moment’s thought is given to them. At a public educational outreach program some years ago, the first question asked regarding a large specimen of glass sponge on display was “can I eat it?”. Fair enough question but seriously, is food and satiating our appetites all we think about when it comes to the ‘value’ of the existence of marine life? That is rather selfish considering that marine life has been around longer than human beings.
The bounty and diversity of seafood provided from the ocean is important for our survival. In some areas of the world, people would not survive without a steady supply of seafood. But if marine life is so valuable for consumption, why are we so reluctant and negligent about protecting the very habitats on which the marine life depends for their survival?
The MLSS (https://mlssbc.com/) has spent decades in Átl’ka7tsem/Howe Sound documenting the diversity of fish and invertebrate species that inhabit the glass sponge reefs (GSRs). MLSS has its educational hands full trying to raise awareness of the importance of these GSRs that are unique to BC and a Canadian treasure. Yet, without the GSR habitats that encompass a diverse community of marine life, where would these animals find protection, shelter, nursery grounds and prey on which to survive? The sponges and the entire food web that inhabits the GSRs, speaks to their value.
In the Salish Sea, two species of glass sponges – cloud sponge (Aphrocallistes vastus), fingered goblet sponge (Heterochone calyx) – build the foundation for these GSR habitats. The rigid skeleton produced by these sponges, is composed of fused spicules made of glass-like silica. Therein lies the physical fragility of these GSRs. But glass sponges are not the only sponges that live in the ocean. Another marine sponge of recent interest belongs to a different group called demosponges. Demosponges, the most diverse of all the sponges in the world, are primarily ‘soft and spongy’, e.g., like a bath sponge, due to their construction from protein spongin fibers. The sponginess of this group, however, can be tempered by the inclusion of varying combinations of calcium carbonate (e.g., like aragonite or calcite found in shells) and silica in the spicules.
What is the recent excitement about in the news?
Sponges (phylum Porifera), especially of the genus Phorbus. Since early research in 1993, marine sponges have been acknowledged as major producers of marine natural products. One such demosponge, the brightly-coloured encrusting demosponge – Phorbas sp. – was collected from Átl’ka7tsem/Howe Sound by a UBC diver as a natural source of diverse chemical structures of potential value for medicinal research. Daoust et al. (2013) discovered several bioactive chemical compounds of interest in the Phorbas species, one of which was alotaketal C. In 2021, Caso et al. suggests that the significance of Phorbas-derived natural products discovered so far are continuing to drive research towards remedies in drug therapeutics and biotechnological applications.
An international and interdisciplinary team based at the University of British Columbia, led by Pérez-Vargas et al. (2022), took another big step forward. Based on previous discoveries, the UBC team worked with 360 compounds derived from natural-based organisms including Phorbas sp. and bacteria. Three of these 360 compounds demonstrated strong bioactivity as potent inhibitors of SARS-CoV-2 highly transmissible Omicron subvariants (BA.5, BA.2 and BA.1) and highly pathogenic Delta variants of concern. The three leading antiviral chemical structures include alotaketal C (Phorbas sp collected in Howe Sound), bafilomycin D (bacteria collected in Barkley Sound, BC) and holyrine A (collected in Newfoundland).
Human lung cells were bathed in solutions made from each of the three chemical structures, before being exposed to a version of the SARS-CoV-2 virus. The result revealed that even very small doses of the chemical structures reduced the viral infection in the lung cells. The different and important feature of these structures is that they are targeting the cells, rather than the virus, thus blocking the virus from replicating and helping the cell to recover. As Pérez-Vargas points out, human cells are much slower to evolve than the viruses, providing potential for the compounds to work against future variants of concern or other viruses such as influenza (A and RSV), assuming that the variants operate in a similar manner to SARS-CoV-2.
The researchers remain motivated by the significant potential of these nature-based chemical structures in the development of wide-ranging SARS-CoV-2 antiviral drug(s) to fight the global pandemic of COVID.
Who would have thought that marine sponges could prove to be so valuable to us?
One more point:
Sponges are called primitive as geologically speaking they are ancient, having evolved some 600 million years ago (Precambrian). That does not imply, however, that they are primitive in their evolutionary fitness. The capacity of sponges to reproduce and generate viable offspring over millions of years and survive to the present day, in spite of warming climate, warming water temperatures, glaciation and sea level changes, and reconfiguration of the world’s oceans through multiple tectonic plate transformations of the earth’s crust, is testament to their incredible adaptability to survive in an everchanging environment.
Sponges are not primitive. They are simple, yet sophisticated organisms. The value of sponges to humans is their capacity to build habitats that provide food for other marine life as well as us, and they hold a diversity of chemical structures significant for the development of antiviral drugs. Surely these are reasons enough to protect the sponges and their habitats.
Note: Neil McDaniel and Bruce Ott have photographed and collected several common, orange encrusting sponges similar to Phorbas in Howe Sound and Sechelt Inlet. Under microscopic examination, Bruce has tentatively identified the sponge they collected as an undescribed species of Hamigera. For more information on these and more details of local marine life, check out
https://www.neilmcdaniel.com/websites.html
Resources
Thank you to Dr. Raymond Andersen, UBC Departments of Chemistry and Earth, Ocean & Atmospheric Science, for providing the Phorbas sp. image.
-Julie Daoust et al., 2013. Sesterterpenoids Isolated from a Northeastern Pacific Phorbas sp.
J. Org. Chem. 2013, 78, 17, 8267–8273. https://doi.org/10.1021/jo4014589
-Alessia Caso, et al., 2021. Exploring Chemical Diversity of Phorbas Sponges as a Source of Novel Lead Compounds in Drug Discovery. Marine Drugs 2021, 19(12), 667: 1-33 https://doi.org/10.3390/md19120667
-Jimena Pérez-Vargas et al., 2022. Discovery of lead natural products for developing pan-SARS-CoV-2 therapeutics. Elsevier Antiviral Research Volume 209, January 2023, 105484 https://doi.org/10.1016/j.antiviral.2022.105484 –https://www.sciencefocus.com/news/covid-fighting-compounds-identified-sea-sponges-marine-bacteria/amp/