When we did the survey in October, we found lots of dead fish like Freshwater minnow、Lake candidus dace . We examined their bodies and found some scars on them. We really wondered what happened to them. Finally, we found an alien species, Red tilapia, which was put in the pond by a parent. He said he put the 4 fish inside because their aquarium box was broken. He put them inside just for a short time. What a disaster in the wetlands!

< Red tilapia in the wetland > by Jing-Jia, Yi-Kai, Chung-Hui, and Chi-Lin

       Red tilapia, which is a violent kind of fish, bothers us a lot. It is from Central America and is about 30-35 centimeters in length. They prefer to live in neutral acid water. The common skin colors are black and  red. On the head of a male fish, there is a  pretty and delicate lump. This species cannot be raised with other fish species owing to its fierceness.  Now, we try to drive them away.
       This invasive species couldn't give up occupying their new territory and bite other fish. This wound caused those fish in death. Mr. Chang invited some fish experts to help. They planned to catch them by fishing. But just only one of Red tilapia got caught compared to other fish which were fished more than one.  We were really sad to see that there was only one illegal emigrant being driven away and most legal residents got suffered.
        
        We tried to trap them with food as they are carnivorous. However, we failed because they have had enough food already. So, we decided to take a more fierce method, which was drawing out all water in the third wetland. Since there wasn't water in the pond, we could get into the pond and tried to catch them by hands. In order not to make water dirty, there were only three of us getting into the pond while others were helping by the pond. We pulled some water grass to prevent Red tilapia to hide beneath it. However, this task was not that easy because the soil in the pond was too soft to walk well.  Therefore, we were asked to go back to our classrooms and Mr. Chang stayed. He caught another one at last. But there were still two inside. Luckily, those tropical fish can't defend the cold current in December. Both of them were dead finally.

       The sad thing is that there are not as many fish as before. However, Mr. Chang had bought some fish at the fish market during winter vacation, and put these new friends in the ponds in the dark.

< The invasion of bullfrogs > by Jing-Jia

The lovely rice field frogs stop their peaceful life since the invasion of bullfrogs. They are called bullfrogs not because their appearance but their bull-like croaking. They are big and strong. They can reach up to  15 centimeters in length. Although they are called bullfrogs, they don't eat vegetables but only meat. So they hunt  smaller frogs all the time.

Listen to the rice field frogs croaking

         The grown males are about 11 to 18 cm in length, and the grown females are about 12 to 19 cm. Their color varies from brownish to shades of green, often with spots or blotches of a darker color about the back. Their skin is smooth and moist. The width of head is larger than its length. The tympanums at both sides are obvious and the mouth is round. Their breeding seasons are in spring and in summer. The male adults usually sit at the ponds croaking. The female adults lay as many as 6000-40000 eggs every time. The diameter of an egg is around 1.2-1.5 mm. Their tadpoles are large with dark spots on the backs and the tails. The length of a tadpole can reach up to 15 cm.

        Bullfrogs are invasive species from North America. They can be bought at the market for the meat or can be used in science experiments .  This invasion species wasn't controlled well so that it can be seen in the wild even in our artificial wetlands. This is really a big threat for the ecology of native frogs in Taiwan.

Listen to the bullfrogs croaking.

< Spirogyra Fighter part I > by Shi-Wei and Chung-Hui

        Recently, a popular topic is always heard. That is the existence of spirogyra found in the survey. The first thing I learned after joining this team is how to clean up spirogyra in the wetlands.  However, I didn't know what spirogyra is and decided to find the answer from the teacher. He told me, "To experience is to learn."

       So, on Saturday morning,  we got into the wetlands and started to clean them up.  The teacher said that the  floating green stuff on the surface of water is called spirogyra. I felt sick though when I saw that . Spirogyra feels like a piece of cloth and soft when touching it. It's easy to get broken and grows rapidly. It is still in the wetlands even we keep cleaning for 3 months. Besides, I found lots of dragonfly nymphs in the spirogyra. The teacher said that they hide themselves inside spirogyra so they can easily hunt for insects. Now I know why dragonfly nymphs are good hunters.

        Why is spirogyra here?  Did anyone plant that in here? We couldn't find the reasons. Finally, our inferences are two. One is that they were brought with the other plants. The other one is that they are brought by birds. However, the teacher told us not to be depressed. He said they will decrease when other plants get bigger owning to the demand of sunshine.

　　

    It was still warm this November, which is good for the spread of spirogyra. When we investigated the wetlands today, we found lots of spirogyra again. So we made the Chinese sweet gum juice again as a therapy for those spirogyra. Amazingly, this juice really works. We found that the amount of spirogyra had decreased after a few days. It is good to use an ecological method to get rid of them.
　The species differ with seasons. Water chestnuts  in summer, oriental cattail in winter, toads and dragonflies in summer and tree frogs in winter are just some of examples. If you would like to know more, please click into our website!