 So, the Philippines is located in an area known as the Coral Triangle. This is a hotspot of marine biodiversity, where we can find a great abundance of species of corals, refish, and other marine organisms. It is therefore unfortunate that this region is also vulnerable to disturbances. For instance, the impact of human activities like fishing and coastal development and the effects of climate change, which include increased precipitation and rising sea surface temperature. In the area of the Coral Triangle and around the Philippines, sea surface temperatures are rising, and it's estimated that temperatures are going up by 0.2 degrees Celsius every decade. Now, while this change might seem like a very small change, it can be very detrimental for a lot of marine organisms. So, thermal stress affects marine ecosystems, particularly sensitive organisms like corals. And corals, when they are affected by thermal stress, can bleach, and eventually this bleaching may lead to mortality. And if scalls are unable to survive, then coral cover will decline. So, what are the things that organisms can do to respond to these disturbances? Well, there's really only two things. They can either evolve or die. And organisms that have survived disturbances have a characteristic known as resilience. This is the ability to cope with stress, to recover from damage that's caused by stress, or to survive and adapt to continue disturbances in the environment. Different organisms have different levels of resilience, and this has effects on the structure of an ecosystem whenever stressors arrive. So, disturbances can cause ecosystems to change depending on the resilience of the organisms within the ecosystem. So, for example, a coral reef that's bleached, that is affected by thermal stress, may eventually be replaced by sponges to become a sponge reef if the corals are unable to recover and adapt. So, what are the mechanisms that allow some organisms to survive disturbances? In order to get at the answers to these questions, it's really important for us to learn from the earliest animals, which are the sponges. Sponges have been around for more than 650 million years, and the fact that they are still present today means that they have the ability to overcome a lot of disturbances in the environment. So, sponges are very interesting organisms because as you'll notice in the present day sponges, they have essentially retained the same body plan and morphology as when they first evolved on Earth. So this is an image of a 600 million year old sponge fossil, and you'll notice that it also has the flattened surface cells that are characteristic of sponges in the modern times, as well as a porous body through which seawater is filtered. So, sponges are a highly diverse group. They are now found in a wide range of habitats, and they come in all shapes, colors, and sizes. Sponges can be classified into four different groups, the Homo scleromorpha, the calcarea, the Demos sponga, and the Hexactinellida. These different groups can be distinguished from each other based on the composition of the organic and inorganic skeleton that make up their bodies. The Demos sponge group is the most species, and is composed of about 8,500 different species of sponges. The fact that the sponges are highly diverse makes them very interesting in terms of exploring questions and adaptation and evolution of animals. Sponges are also important components of reef ecosystems. They filter large quantities of seawater. They contribute to nutrient cycling. They provide food and habitat for other organisms, and they contribute to ecosystem structuring. Furthermore, sponges are also very important in substrate modification. Like a lot of other marine invertebrates, sponges also have a bi-phasic life cycle. This means that they have a swimming pelagic larvae, which will settle onto the substrate and metamorphose into the adult. The fact that sponges are exposed all the time to their environment means that they're highly vulnerable to stressors. But having a swimming larvae means that they also have the opportunity to swim away to find an alternative habitat where they might be more protected from disturbances. So sponges have the potential to be resilient. However, there are very few studies that have actually explored how climate change will affect sponges. And certain sponges, like Haliclona to Bifera, are found to thrive in very shallow reef flats that experience a wide dynamic range of temperature every day. So this particular sponge makes it a very interesting model organism to look at questions on how organisms like the sponge are able to develop resilience to environmental stress. To understand how marine organisms are able to develop resilience to disturbances, we can use many techniques. For example, we can do genomics to look at the DNA content of an organism. We can do transcriptomics to look at RNA molecules, or we can do proteomics to look at the proteins that are expressed within the tissues of an animal. These different methods have their own advantages and disadvantages. For example, genomics methods, although they allow complete identification of all the genes that are present in an organism, this method can be computationally intensive. On the other hand, proteomics allows us to look at all the functional proteins within a cell, but this method can be quite technically challenging. So the method of choice for looking at responses of organisms to environmental conditions is now transcriptomics. This only allows us to get a partial identification of the genes in an organism, but it does allow us to get a snapshot of all the genes that are expressed at any particular time or under specific conditions. So this is the method that we use to look at how our sponge responds to stress. So what we do is first we expose our sponges to different temperature treatments, we then collect the RNA sequences from the sponge, and then we perform analysis to identify what genes are responsive to the temperature treatments that were applied. Using transcriptomic methods, we are able to identify many immunity and stress response genes in Haliclona-Tubifera. This graph shows you the abundance of genes in different families that are important in immunity and cell adhesion. What you'll notice here is that Haliclona-Tubifera, which is represented by the red bars, has a comparable number of genes in each of the different families as another sponge, Haliclona-Ambunensis, which is represented by the yellow bars, and Amphimidon-Queenslandica, represented by the green bars. You see a similar pattern when you look at genes that are important for the stress response. Again, Haliclona-Tubifera has a similar number of these genes as the other sponges that we are comparing it to. What this indicates is that Haliclona-Tubifera must indeed have the potential to be tolerant and to be able to adapt to thermal stress. What we find when we expose Haliclona-Tubifera to elevated temperature is that many of its genes are affected by thermal stress. Some genes go down in expression as represented by the blue dots, while some genes increase in expression as represented by the red dots. What this shows you is that the Haliclona-Tubifera transcriptome is highly dynamic and is very responsive to changes in its environment. One of the families of proteins that are most important for responding to thermal stress are the heat shock proteins. When we look at heat shock proteins in Haliclona-Tubifera, we find that many of these genes are actually increased in expression after just four hours of exposure to elevated temperature. Interestingly, we find that after prolonged exposure to higher temperature, many of these heat shock proteins go back to their control expression levels. What this data indicates is that while heat shock proteins are indeed important for the immediate response to thermal stress, other mechanisms might be used after prolonged exposure to high temperatures. To understand the cellular processes that are deployed in response to thermal stress, we performed an analysis known as genontology enrichment. This method allows us to look at all the cellular functions that are enriched in the set of genes that are responsive to whatever conditions we apply. In this case, we're looking at thermal stress. So using this method, we find that genes that are related to the immune response as well as protective responses like antioxidant activity are actually enriched in the sponge, particularly at short-term periods after exposure to stress. We find that functions related to signaling as well as transporter activity are similarly enriched. And upon prolonged exposure to thermal stress, we find an enrichment in functions related to protein folding, tissue development, proteolysis, and regulation of metabolic processes. This tells us that haliclona-Tubifera is able to deploy different mechanisms that enable it to deal with thermal stress at various levels and at different durations of exposure. Taken together, all of this data indicate that haliclona-Tubifera must indeed be resilient to thermal stress. And the mechanisms that allow the sponge to be tolerant to elevated temperature include the availability of protective mechanisms, which include your heat shock proteins and antioxidant activity that protect your cells from damage, as well as repair mechanisms that are then able to maintain cell and tissue integrity in case of damage caused by stress. For prolonged exposure to elevated temperatures and other stressors in the environment, it's also important for the sponge to be able to mount a sustained response. This involves triggering signal transduction and the production of new gene products. The gene products that are produced help the sponge to modify its tissues and to perhaps improve its phenotype to provide it with an added advantage in an environment that is impacted by stress. The mechanisms that are shown here for haliclona-Tubifera might also be extended to other organisms and other sponges in the marine environment. However, it's important for us to remember that different organisms will have evolved different mechanisms to deal with stress because they all encountered different environments during their evolution, and these different survival solutions contribute to the diversity of organisms that we see today. This emphasizes the importance of being able to explore and to study the diversity found in regions of high biodiversity like the coral triangle and around the Philippine archipelago. This will allow us to gain a better understanding of how organisms are responding to their environment and especially the effects of climate change on marine ecosystems.