While sorting through and identifying the fish species that I collected for my master's thesis project, I came across a species that was unknown to me. This tiny brown fish was nothing spectacular, save for the unicorn-like appendage between its eyes. I instantly fell in love with this oddball, as it was nothing like I'd even seen before. After exhausting all attempts at trying to identify it using guides and dichotomous keys, I reached out to several colleagues who were familiar with Red Sea fishes. We quickly came to the conclusion that it was indeed a new species of goby, possibly even a new genus. Having only collected two individuals during my fieldwork, I quickly set out to attempt to capture more. As any small fish enthusiast knows, collecting these tiny, cryptic fishes is most akin to searching for a needle in a haystack. I went back to the same reef where I had collected the previous two specimens, and went to work. I knew that the previous fish were collected near the substrate in a rubble environment, so that is where I focused my search. It takes a careful eye to find cryptic species underwater, as they are easily overlooked and will often hide in minuscule holes and cracks. After about a half hour of searching and not finding much, I came across a soccer ball-sized rock at the bottom of the reef. I could see small fish darting around the rock, and then disappearing into pencil-sized holes. I swam closer to the rock, my face inches from it, and was surprised to see tiny faces peering back at mine. I was thrilled to have found so many individuals, so I quickly collected what I could, then headed back to the boat. After returning from my collecting trip, I sent off several specimens to expert taxonomists for the painstaking identification work. After examining both morphological and molecular data, we concluded that the fish belonged to a new genus as well as a new species. We christened it Cerogobius petrophilus, meaning rock-loving horned goby, in honor of the fish's preferred habitat and horn-like appendage. FIGURE 3. Cerogobius petrophilus sp. nov. A: paratype, SMF 35963, female, 14.81 + 2.97 mm, freshly collected specimen, Thuwal, Saudi Arabia. Holotype, SMF 35961, female, 16.32 + 3.54 mm, Thuwal, Saudi Arabia, B: freshly collected specimen; C: preserved specimen. Photos by E.M. Troyer (A & B), M. Kovačić (C). I love doing biodiversity research, because there is so much on this planet that we have not discovered yet. Taxonomy can be viewed as the foundation of biology, because it becomes nearly impossible to do research on an organism, when you don't know what it is. Furthermore, in the recent wake of global climate change, collecting and cataloging the diversity of life is becoming increasingly important as many species face the threat of extinction. To read more about this study, check out the recent publication in Zootaxa: Kovačić M, Bogorodsky SV, Troyer EM, Tornabene L (2019) Cerogobius petrophilus (Perciformes: Gobiidae), a new gobiid genus and species from the Red Sea. Zootaxa 4565(2): 171-189
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My master's thesis project examined microhabitat association of gobies and other small, cryptic fishes in the central Red Sea. To put it simply, a microhabitat is defined as a subset of a larger habitat. Some examples include: the bark of a tree, a specific coral head on a reef, a patch of stones, etc. Gobies are of particular interest to me because they are one of the most speciose families of fish. There are over 1,800 species in the family Gobiidae, with more being discovered every year. Gobies are also very small, often no larger than a few cm in length. Despite their size, they are incredibly numerous on coral reefs. However, being cryptic, they are hard to sample. Visual surveys of reef fish will often not account for them because gobies are small and like to hide in small cracks and crevices. A good way to account for these species on a reef is to use an ichthyocide (like rotenone) when sampling. I looked at 3 different microhabitat types: hard corals, sand, and dead coral rubble. Once I found a suitable site, I placed a 1m x 1m quadrat over the chosen microhabitat. I had a net to place over top the quadrat, to prevent fish from escaping. Then I administered the rotenone and waited about 5 minutes for everything to settle. After the time was up, the net was removed and the fish were collected. After I collected my samples, I took the fish back to the lab and photographed each one individually. Then, I cataloged and identified them using both morphological and genetic methods. I used DNA barcoding as an identification tool and the DNA sequences I obtained from my samples are uploaded to public sequence databases, such as GenBank. They will be useful to future researchers and provide genetic information about these understudied species. I collected over 300 individuals and found that even at small scales of a few square meters, benthic composition influences community structure of cryptobenthic fishes in the Red Sea. Fish assemblages differed significantly across all three habitats, with rubble habitats having the highest levels of fish abundance, species richness, and diversity, followed by hard coral, and then sand. Boxplots displaying abundance (number of individuals per m2), species richness (number of species per m2), and diversity (H′) for all collected fishes (A, C, E) and for family Gobiidae (B, D, F) for each of the three microhabitat types sampled using rotenone stations (1 m2 quadrats, n = 5 quadrats per microhabitat type) in the central Saudi Arabian Red Sea. Asterisks denote significant pairwise groupings (*p < 0.05, **p < 0.01, ***p < 0.001). This work is important because the Red Sea is a historically understudied area in regards to biodiversity. Gobies and other cryptobenthic fishes are also understudied due to their cryptic and hidden nature. It is my hope that this project will raise awareness of cryptobenthic fish biodiversity in the Red Sea and provide a basis for future work regarding Red Sea species. This work was recently published in PeerJ: Troyer EM, Coker DJ, Berumen ML. (2018) Comparison of cryptobenthic reef fish communities among microhabitats in the Red Sea. PeerJ 6:e501 https://doi.org/10.7717/peerj.5014 I finally had a chance to create my own site. I will hopefully use this space to write a bit about my research over the years, and all the fishy things I have done. Also, stay tuned for fun fish facts!
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AuthorThis blog will be where I will talk about my research experience and where it has taken me over the years. Archives
July 2019
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