Explained: How Climate Change Is Responsible For Sea Sponge Bleaching

Mass bleaching of sea sponges has been discovered along New Zealand¡¯s southern coast raising concerns over the impact of global warming and climate change.

The sponges should be brown in colour but due to the rising temperatures of the ocean the sponges turned white.

What are sea sponges?

Sea sponges are among the most basic multicellular organisms on the planet. They come in a variety of sizes, colours, and textures.

Photo: DR VALERIO MICARONI - FRANCESCA STRANO - VICTORIA

Sea sponges feature a shell-like or glass exterior layer with small pores (ostia) that penetrate deep into the soft interior structure. Water can flow in and out of the sponge through these pores. The sponge collects food and oxygen while also releasing waste which serves as food for other animals. These sponges also create tree-like, cup, and tube shapes, creating a forest-like structure. These so-called "sponge gardens." serve as shelter for a lot of other animals.

What causes the bleaching of these sponges?

Photo: DR VALERIO MICARONI - FRANCESCA STRANO - VICTORIA

The sea sponges have tiny organisms that capture sunlight and make food through photosynthesis. The sponges depend on this food for survival. When water temperature rises, much like corals, these sponges push out these photosynthesizing organisms. In addition to food, these organisms are also a source of their colour. Hence, when sponges push them out, the sponges lose their colour (and turn white) as well as their source of food.

Why does it matter?

Sea sponges serve a crucial role in the marine ecosystem, providing refuge and food for species such as crabs, algae, and fish. Further, sponge gardens are found all over the country and play a crucial role in generating fish habitats and releasing carbon that is consumed by other species. As part of the food chain, their extinction might have major ramifications for fish populations.

What does it convey?

Photo: Dr-Valerio-Micaroni-and-Francesca-Strano,-Te-Herenga-Waka¡ªVictoria-University-of-Wellington

The bleaching event is another example of the ramifications of global warming and climate change.The scientists from Victoria University of Wellington were alarmed at the discovery off the coast of New Zealand in Fiordland.

James Bell, a professor at the university said,¡±this could be the start of something really really bad for other ecosystems or the entire ecosystems in Fiordland". He went on to say that, ¡°This just highlights the kind of climate crisis that we¡¯re facing¡±.

Due to climate change, the world's oceans were the hottest in recorded history last year, which can cause the oceans to acidify and destroy reefs and ecosystems, among other things.

Although further research is needed to establish definitively whether the bleaching is due to rising ocean temperatures, this very event in culmination with others is a testament to how devastating the climate change crisis is and what the crisis has in store for us if we do not take action to tackle the crisis.

References

¡°Bleached sea sponges found off New Zealand for the first time - CBBC Newsround.¡± 2022. BBC.

Cardwell, Hamish. 2022. ¡°Mass bleaching of native sea sponges in Fiordland shocks scientists.¡± RNZ.

Corlett, Eva. 2022. ¡°Bleached sea sponges found in New Zealand waters for first time.¡± The Guardian.

Kennedy, Jennifer. 2019. ¡°Sea Sponges Facts - Porifera.¡± ThoughtCo.