Ruhl EJ, Dixson DL (2019) 3D printed objects do not impact the behavior of a coral-associated damselfish or survival of a settling stony coral. PLoS ONE 14(8): e0221157. https://doi.org/10.1371/journal.pone.0221157
3D printing a habitat
3D printing is a new technology that can be useful in many ways. We usually hear about 3D printed items being used in manufacturing, construction, or even medicine, but 3D printing is now being explored in the field of ecology. 3D printed objects can be useful to re-create small scale models of species and habitats that aid in research. Some natural habitats can be challenging to study. Often, focal study species and habitats are vulnerable and are not able to be manipulated or replicated. For example, coral reefs are threatened all around the world and can not be easily studied within their natural environment. 3D printing artificial corals can offer more quantitatively repeatable and less invasive alternatives to field studies which may do more harm to these threatened species and their ecosystems. A recent study by researchers Ruhl and Dixon from University of Delaware tested the impacts that 3D printed corals have on damselfish behavior. Damselfish, or more specifically, the blue-green chromis (Chromis viridis), is a species of fish that lives within coral reefs. The reefs are an important habitat for the chromis by providing protection from predators. This study explored whether the presence of various 3D printed corals affected the behavior of the blue-green chromis when compared to the presence of a natural coral.
How it works
In a laboratory setting, blue green chromis fish were exposed to two species of coral that were replicated as 3D prints: one with long, wide set branches (Acropora formosa) and a bushy coral (Pocillopora damicornis). Both species provide protective habitats for blue green chromis in the wild. Next, coral skeletons were 3D printed on four different types of filament, i.e., thermoplastic material used for 3D printing, including one biodegradable filament, polylactic acid (PLA). The blue green chromis were exposed to all four types of filament as well as a natural coral, and the time the fish spent associated with each type was recorded. This tested whether the fish showed a preference for type of filament the 3D coral was made from, and if the fish preferred a natural coral over a 3D printed coral.
The blue-green chromis did not prefer one coral type over another, which indicated that the habitat choices of the fish are not influenced by coral shape. Interestingly, results also showed that the fish did not prefer one type of filament to the other, and there was no difference of preference between artificial coral and the natural coral.
What does this tell us?
Before we can really decide if 3D printed coral can replace natural coral in field experiments or in nature, laboratory tests like this one are vital to understand the basic response of a species to its altered habitat. Because the blue green chromis fish did not respond unusually to 3D printed corals, it is safe to say that the 3D printed coral habitat was not a stressor on this species, and none of the different filament types were a deterrent. Tests like these should be repeated with other reef fish or organisms that call coral reefs home. The next step is to field test the 3D coral by observing the response of reef organisms in the wild to the artificial structure.
The future of 3D printing in ecology
Using 3D printed corals for reef studies can provide several benefits. One is to alleviate stress on a reef that would naturally be incurred during field experiments.. Another benefit to using 3D printed corals is to replace live coral when appropriate or needed, like when a reef dies. 3D printing is ultimately cost effective, easy, and precise, and can be replicated quickly. It can even be environmentally friendly! This study showed that the blue green chromis showed no preference for filament type. Therefore, PLA, a biodegradable filament, could be used in place of other plastic filaments to minimize the microplastics that enter the environment. When it comes down to it, 3D printing is a technology that can provide innovate conservation methods for reef species, and likely other habitats as well.