A paper just published in the Journal of Animal Ecology [1] looks at how sharks scare dugongs and increase seagrass in a tropical environment. While their modelThe process, either mathematically or in the human brain, of creating an internal version of something that we can refer to, to better understand how it functions and our place within. Scientific modelling is where we take the best knowledge we have and build a version of what will happen, if we assume certain parameters. For example, we might model More is relatively simple, it reveals something of the complex and non-linear effect of relationships between animals and their prey in the food chainA single thread in a food web illustrating the chain of animals that eat each other. At the base of the food chain are small high-energy (fast metabolism) animals and at the other end large low metabolism animals. An example would be whales eating krill that eat plankton that eat algae. Or lions that eat gazelles that eat grass. More. The study is yet another example of why animals are important to us.
The scientists reveal that sharks are seasonal and their appearance might scare dugongs away from seagrass patches, giving the seagrass time to regrow. Seagrass is a crucial weapon against sea level rise, for example, which is a consequence of climate change.
Seagrass is also a major part of the carbon cycle. When Dugongs graze seagrass, they are also increasing its carbon content. In Indonesia, one study found that Dugongs removed 93% of seagrass shoots and three-quarters of growth from four centimetres below ground but it only took five months to recover and the consequence was, more carbon stored overall. The grasses bounced back stronger, thicker and more diverse [2].
It’s nice to see researchers referring to the importance of animals for both stability of ecosystemsHow ecosystems function An ecosystem is a community of lifeforms that interact in such an optimal way that how ecosystems function best, is when all components (including humans and other animals) can persist and live alongside each other for the longest time possible. Ecosystems are fuelled by the energy created by plants (primary producers) that convert the Sun's heat energy More and biodiversityWhat is the definition of biodiversity? When we ask, what is the definition of biodiversity? It depends on what we want to do with it. The term is widely and commonly misused, leading to significant misinterpretation of the importance of how animals function on Earth and why they matter a great deal, to human survival. Here I will try to More. In an interview with the scientists in the Bangor Daily News, it was said that:
“The team found that predators, like some sharks, including tiger sharks in this study, are critical for maintaining stability and biodiversity in the world’s oceans”.
I recently wrote about how boom-bust cycles between predator and prey work, in another blog article about sharks. Beyond thinking about what eats who and how much, have a think about what the movement of animals means too. The evolution of patterns of behaviour and migration of animals, in particular, are really significant factors in ecosystem resilienceReferring to an ecosystem’s ability to maintain a steady stable-state. The need to build resilience is entirely anthropocentric and symptomatic of ecosystems that are damaged or declining, leading to loss of ecosystem services on which humans depend. More and stability and it’s why we can’t simply genetically-engineer new animals and expect their ecology to work.
Marine predators benefit from periods when there is less surface productivityThe power of an ecosystem to process energy. The most productive ecosystems have reached a steady stable-state with maximum entropy production. That’s to say, the number of species has reached an optimum and the functions they fulfil, have translated free surplus energy into nutrients that is either stored inside plants and animals, or is entrained within the biological cycles that More … but only as long as there are plentiful periods in between. This boom-bust cycle, where animals expand and then contract geographically, is necessary to allow recovery of fish populations. Fluctuations in the numbers of predator and prey can then track each other closely over the long-term
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How do you reduce shark attacks? Try increasing shark numbers
Ecology is a complex science and so often, our simplest assumptions about how things work, don’t hold up in practice. Take sharks for example. How do you reduce shark attacks?…
- Nowicki, RJ, Thomson, JA, Fourqurean, JW, Wirsing, AJ, Heithaus, MR. Loss of predation risk from apex predators can exacerbate marine tropicalization caused by extreme climatic events. J Anim Ecol. 2021; 00: 1– 12. https://doi.org/10.1111/1365-2656.13424
- Iongh, H.H., B.J. Wenno, and E. Meelis, Seagrass distribution and seasonal biomassThe weight of living organisms. Biomass can be measured in relation to the amount of carbon, the dry weight (with all moisture removed) or living weight. In general it can be used to describe the volume of energy that is contained inside systems, as the size of animals relates to their metabolism and therefore, how much energy they contain and More changes in relation to dugong grazing in the Moluccas, East Indonesia. Aquatic Botany, 1995. 50: p. 1-19.
