This past week in my research, I have finally started one of my experiments. This experiment involved using adult Dungeness crabs, juvenile Dungeness crabs and mussels. Just to recap exactly what this experiment consists of, there will be three different treatments but five replicates of each treatments. The first treatment contains ten juveniles and one adult crab. The second treatment contains ten grams of mussels and one adult crab. The final third treatment contains the first two treatments combined which means one adult, ten juveniles, and ten grams of mussel. The final treatment is what will be directly proving or disproving my hypothesis, mussels as an alternative food will cause a positive impact on their cannibalistic behavior. By positive impact, I mean that the crabs would much rather prefer eating the mussel rather than each other. In order to get accurate results, I will need monitor treatment 3 hourly to see what the crabs prefer to eat first, will the mussels be eaten first or last? At the end of next week, I will finally have some results to report.
This week, we had our weekly seminar as usual where a guest speaker comes to present and talk about research that they have been doing. This week we had Dr. Glenn Ford from UC Santa Cruz present research he did on the impact that oil spills inflict on sea birds along the Oregon and California coast. This was by far the most interesting research seminar that I have listened to. Dr. Ford used his research results and extrapolated from them to predict the areas and amount of sea birds that would be affected in any future oil spills.
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After presenting my research to my colleagues and listening to their feedback and comments, I decided to restart any treatments that I have completed up to this point. I was originally doing one treatment every couple of days, but this can bring up some confounding variables such as time of day, sea water quality and the conditions of the crabs. To minimize any error that may result from these variables, I must start all the treatments for one experiment at the same time; which means 75 juveniles, 200 megalopa and 50 grams of mussels in 15 containers all running at the same time for experiment one and 15 adults, 100 juveniles and 100 grams of mussels in 15 fish tanks for experiment two. This week I spent my time getting prepared to start my first experiment. The only issue that I am coming across is for experiment two in finding enough fish tanks that are similar in size to use for 15 adult crabs at the same time. I only have access to five fish tanks that are identical, so to compromise with what is available, I will be using large containers. These large containers are not identical to the fish tanks so the rate of contact between crabs in the fish tanks will be different from the rate of contact in the large container. To work around this, every treatment will have the same number of fish tanks versus large containers.
This weekend, Nicole along with the other interns and I drove up to Newport to visit the Hatfield Marine Science Center and the Oregon Coast Aquarium. At the Hatfield Marine Science Center, we got a tour of the labs and classes that they offer directly from OSU. We also met and had an ice cream social with the research interns of Hatfield. This week in my research, I completed my second experiment. This experiment contained five treatments, each consisting of five juveniles and 20 megalopae. At the end of this experiment, only the original five juveniles in each treatment were left, all the megalopae were eaten. However, throughout the four days that this experiment was running, I checked on them a few times for updates. After one day, only two treatments had two megalopae alive. The rest of the treatments had none meaning that the juveniles ate all of them. The following day, the two treatments that had two megalopae did not have any megalopae anymore. Instead they both had six juveniles instead of five. This means that one of the two last remaining megalopae morphed into a juvenile and the other one was eaten. On the final day of the experiment, the new sixth juvenile was no longer existing. I hypothesize that since it was such a small juvenile that was still relatively small compared to the other five juveniles, it had no fighting chance and was eaten by the others. This experiment successfully showcased their cannibalistic behavior. The next experiment that I started this week was a redo from the experiment I did last week. The reason for a redo is because only two of the treatments had juveniles that ate the mussels. The other treatments had mussel that was not eaten. To prove that mussels are a valid food source for crabs, all treatments must have the juveniles eat the mussels. This experiment is vital to answering my research question.
Hello, week 3 is now coming to an end which also marks the end of an eventful week. For my research this week, I completed my first trial that tests my research question, how does the availability of alternative food influence cannibalism in Dungeness crabs? This first trial contained five replicas of a bucket filled with 96 ounces of water, five juvenile crabs, and about five grams of mussel. This trial is designed to test that mussels are a food source that the crabs could survive on. The reason behind doing five trials and starting them at the same time, is to increase our chances of getting consistent results and not have them be because of ‘random chance’. Within the five replicas, I made sure to keep the subjects consistent as well. By this I mean that all juveniles used ranged between 13 cm to 17 cm in carapace width and all mussels were similar in size and weighed five grams. After 4 days of observations, two of my treatments had crabs that ate all the mussel provided, two other treatments had crabs that almost ate the mussel completely and the last one had a mussel that was not touched at all by the crabs. In the end, treatments 1, 2 and 3 all had a crab who molted, treatment 2 had one crab who was missing one leg and lastly treatment 3 had a crab that was missing three of its legs! Since both of those treatments were also the same ones that a molt in them, my hypothesis is that the crabs who lost their legs were the ones who molted as well. When a crab molts, their exoskeleton is soft making them vulnerable which could have lead to other juveniles taking advantage of this and possibly tried to eat the crab, leading to their missing legs. The next trial that I will be starting will be five replicas that contain 5 juveniles and 20 megalopae. This replica will be testing the cannibalistic behavior of the juvenile crabs. This past weekend, the other interns and I went camping Saturday night at Cape Argo. This was my first time camping ever, so going into it I did not know what to expect. What I liked most but also seemed odd to me at the same time was that the campsite was right next to a beach! As a first time camper, when I thought of camping, I pictured us sleeping with wildlife and being lost in nature. But I’m happy to say that wasn’t the case and I had a great time. Early next morning, we all went tide pooling at South Cove. We found lots of Gumboot Chiton and Sea Urchins! The tide pools here in Oregon are filled with so much more marine life than tide pools from Southern California. This week was also fourth of July, so everyone at OIMB, interns, students and faculty, attended a picnic down at Sunset Bay. There was lots of delicious food and I ate oysters for my first and possibly last time. Something about the rubbery texture it had as I ate it did not make it seem as appetizing when I was curious to try them. I also participated in the annual OIMB 4th of July Egg Toss. I played twice and placed top 4 both times!
Week 2Hello, week 2 is now coming to an end and I am happy to say that I have a set research project. The question that I will be exploring is, how does the availability of alternative food influence cannibalism in the life cycle of Dungeness crabs? To give you a little background on the life cycle of the Dungeness crabs, their hatching occurs around January-March if they’re located in Oregon. In the first stage of their life cycle, they are called Zoea and go through six different phases (1 pre-zoea, 5 zoea) before entering the second stage and growing into Megalopae. To get to the Megalopae stage, it takes them about three to four months. In the megalopae stage, they are just a little under 1cm in length. They remain in the Megalopae stage for about a month, until finally becoming juveniles where they grow for two years before finally reaching sexual maturity as an adult crab. My project includes crabs as megalopae, juveniles and adults. To test out their cannibalistic behavior, I will be having different aged crabs mixed with each other in separate tanks, some with an alternate source of food and others with no alternative. For example, in one tank I will place juveniles with megalopae, and in a separate tank juveniles with megalopae and mussels as an alternative food source. I conducted several quick and dirty experiments similar to that example this week to test and see quick results. Within 24 hours, all the megalopae that were in a tank with only juveniles, were completely gone; the juveniles completely devoured them. In a second quick experiment, I placed one adult crab with 10 juveniles and, within 24 hours, the juveniles were all gone. These two quick experiments basically showcased their cannibalistic behavior so to further explore that behavior, I created an experiment involving juveniles and mussels. The meaning of this experiment is to test that mussels are a food source for crabs, so that when crabs are given the choice of choosing food, they will either choose cannibalism or mussels. After 24 hours, this experiment ended up failing. Interestingly enough, when I came into lab this morning, the crabs that were feeding on the mussels were dead. Alan suggested that, the cause for their death was likely too much food leading to excessive decay and anoxia. The ratio of crab to mussel was too low, so I need to figure out a perfect ratio of prey to predator. In that experiment, I had about 10 grams of crab in the tank and 150 grams of mussels, which is 15 times the biomass of the crabs! Next week, I will be perfecting my experiments to help start my trials that will help test my hypothesis. Outside of my research, this past weekend the other interns and I went on a boat trip to go dredging out in the ocean. Fortunately enough, I did not get seasick and thoroughly enjoyed the boat ride. This weekend we are camping at Cape Argo to go tide pooling early in the morning!
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AuthorMy name is Juan Flores and I am an intern in Alan Shanks’ lab. I am from a small city in the Los Angeles County, Pico Rivera, California. I will be transferring to the University of California, Santa Cruz in the Fall, pursuing a Bachelors in Biology. Archives
August 2018
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