August 3rd, 2015 – Fish Seining and Identification / Biology of Wetlands / Aquatic Reptiles

August 3rd, 2015 – Fish Seining and Identification / Biology of Wetlands / Aquatic Reptiles

[2015年8月3日]围网捕鱼与鉴定/湿地生物学/水生爬行类讲座

Blog entry written by: White Winged Scoter (Melanitta deglandi)

Team Members: Manreet Kaler (Western), Chang Liu (Tongji), Mengxi Wu (SWU), Anyi Tang (Fudan)

Weather: Windy, cloudy and some precipitation, Temperature: 17-27° C

This morning, we started by learning the fundamentals of fish seining. We had the pleasure of having two very experienced fish seiners, Changhai Zhu and Professor Madison in addition to Professor Wong to lead this practicum. We started off by taking out the fish seining net and learning about its uses. The top part of the net is called the floater and the bottom part of the net has weights on it. This type of net is only good for fish seining along shorelines and not for deep water as it is not wide enough. It is very important to select your area very carefully, which is one of the steps in being a good biologist.  Another imitation to using this method, is that other species such as turtles could get stuck into the net and hence suffocate causing them to eventually die. This can be prevented by having constant observation. In addition, fish seining is not the only way to catch and identify fish, as you can also set traps with bait, or set up gill nets to catch a school of fish.

The class was divided into two large groups of about 16 people each. While the first group was fish seining, the second group, which we were a part of, was working on the wetland assessments. After the first group came back, we were taken by van to a part of Lake Opinicon, within Queens biological station, which was only about a two minute drive (18T E394486 N4935626).  The first part in this fish seining and identification practicum was to put the net into the water, with one person on each side to spread it out. This was followed by the use of two volunteers who helped with putting the net in the proper position to allow fish to be caught within. Once the net was spread accurately, Professor Wong and some of the other students were able to round it up to keep the fish from escaping the pocket underneath, which is built in the middle of the net. Once the fish were securely in the net, we took them out and transferred them into buckets.

The reason for putting all the fish that were collected by the net into three different buckets was to help count and identify them individually. The three buckets were brought out of the water, and using the “Peterson Field Guides: Freshwater Fishes” we were able to successfully learn and classify the fish accordingly. As we would take one fish out of the bucket, with help of all the professors, we would state the fish species and then put it into a larger bucket. We also had to make sure to count how many of each species of fish we had collected in order to get a better understanding of the types of fish that reside by slow moving shorelines.

All together, we collected 158 fishes, of 7 different species, including Pumpkinseed (Lepomis gibbosus), Bluegill (Lepomis macrochirus), Yellow Perch (Perca flavescens), Largemouth Bass (Micropterus salmoides), Banded Killifish (Fundulus disphanous), Bluegill Pumpskinseed Hybrid, and Juvenile Chub (Hybopsis). The data collection is shown below.

Table 1. The number of fish collected according to their specific species.

Fish Species Number Collected
Pumpkinseed (Lepomis gibbosus) 38
Bluegill (Lepomis macrochirus) 90
Yellow Perch (Perca flavescens) 20
Largemouth Bass (Micropterus salmoides) 6
Banded Killifish (Fundulus disphanous) 1
Bluegill Pumpskinseed Hybrid 2
Juvenile Chub (Hybopsis) 1

Each species of fish were identified based on different characteristics including, size, gill, dorsal fin, scales, colour, etc. The Pumpkinseed, a type of sunfish can be identified as having one dorsal fin, with many bold dark brown lines and orange spots. It also has bright red and orange spots with a light coloured edge on the black earflap. Pumpkinseeds are found by the shoreline, as they are tolerant to hypoxia. They have a small mouth and many gold and yellow flecks. Bluegills which were the most common fish found in our sample, are not as tolerant to hypoxia as Pumpkinseeds but are also a  type of sunfish. It can sometimes be hard to identify between a Bluegill and a Pumpkinseed. Bluegills have large black spot at the rear of the dorsal fin. They have a long pointed pectoral fin which extends past their eye. They also have a small mouth, as their upper jaw does not extend under eye pupil. They have blue streaks from the chin to the edge of the gill cover, and are white to yellow below.

We also found a couple fishes of other species that were not as common. The Yellow Perch for example has a fairly deep compressed body. It is green above and has some yellow on the side. It also has a larger mouth than some of the other fish and yellow paired fins. Furthermore, the Largemouth Bass has a very large mouth in comparison to everything else that was caught today. It is silver and brassy green above with a dark olive mottling. Another type of fish that we identified was the Banded Killifish, which are found to be pretty rare around this area, have long slender bodies, with green and brown bars along the silver side. They also have a brown stripe along the back. The hybrid that was caught is a hybrid between the Pumpkinseed and the Bluegill. These are actually fairly frequent in aquatic shoreline habitats. The final type of fish that was caught was the Juvenile Chub. There are many different Chub species, and it can be hard to identify Juvenile Chubs since they are very small and not fully developed.

Once we identified and recorded all the fish species that were collected, we placed them all back into the lake. It is important to be efficient since you do not want to keep the fish out of their habitat for a large amount of time, as it can eventually be detrimental. We noticed that it was irritating for some of the larger fish to be constrained to a bucket, as it was a small amount of space. As a good biologist it is important to know the different fish species well so that when you are identifying, you can do it accurately but also at a fast pace. Once we placed all the fish back into the lake, we made our way back to the main lodge of Queens Biological Station by foot.

After having a delicious meal at lunch, we continued the day with two exciting lectures lead by Professor Wong and Professor Lougheed in the seminar room. The first lecture was on the biology of wetlands. Professor Wong explained the definition of wetlands and how to classify them. Wetlands are an area permanently or recurrently inundated or saturation at the near surface by surface water or ground water. Wetlands have certain characteristics such as, soils are water saturated, vegetation is dominated by large and unique plant species, and they share features with the aquatic and terrestrial ecosystems as well.  There are two main things that make the wetlands unique: 1. Anaerobic soils, which are saturated soils that are quickly depleted by microorganisms and 2. Macrophytes, which are large plants such as ferns, shrubs, trees and grass. It is very crucial to understand the importance of the wetlands, in order to sustain local and regional biodiversity. There are many different wetlands, such as bogs, swamps, ferns, shallow water, and marshes. Within these wetlands they will have different landforms as well as different climates. The wetlands hydrology will also play a role in the kind of vegetation that will grow.

The final lecture given by Professor Lougheed on aquatic reptiles explained the different reptile species that we may find around the world as well as around Ontario. He also provided the class with an understanding of the importance of different reptile species, such as turtles, crocodiles and lizards and their endangerment concerns. These species are keystone species meaning that they are very important, as other species are very dependent on them. Some characteristics of reptiles include: they are ectothermic, mostly lay amniotic eggs, some have pits for infrared sensing and all breathe through their lung but some have permeable skin and respire through their cloaca. Some examples of reptiles include: Leather back sea turtle (Dermochelys coriacea), Eastern long-necked turtle (Chelodina longicollis), Saltwater crocodile (Crocodylus porosus), Northern water snake (Nerodia sipdon) and Marine iguana (Amblyrhynchus cristatus). There is an extinction crisis among reptiles. There has been a 50% decline, recorded from the global living planet index from 1970-today. Reptiles serve importance not only to their ecosystems but also to us. Snakes for example, can serve as predators for some pests. In some cultures they are used for food and leather. Snake venom recently is being used for medicine purposes as well. Therefore by understanding reptiles we can then try to help in playing a role to conserve them.

We ended the day off after dinner by working on our wetland assessments. Today was filled with many amazing learning opportunities and also lots of fun working in the field.

早晨,我们学习了用围网捕鱼的基本方法。我们非常高兴能够在两位有经验的围网捕鱼者朱常海和麦迪逊教授以及王教授的指导下上实习课。我们首先拿出了渔网并学会如何去使用它。网的最上面是浮漂,最下面可以承受一定的重量。由于这种网不够宽,因此它只适用于沿岸的围网捕鱼而不适用于深水地区,同时,仔细选择围网捕鱼的地点也很重要。除此之外,其他的物种像如乌龟也很容易进入网中并最终造成窒息而死亡,我们可以通过长期观察去避免。在捕鱼时,我们也可以在网中放入一定的诱饵,这对我们抓鱼也有一定的帮助。

整个班级被分成两个小组,每组16人。第一组在进行鱼类学习时,第二组浏览湿地考察相关文件。11点左右我们第二组出发,来到了。。。渔网被展开,然后缓缓收紧,鱼被压进网兜以防溜走。同学们纷纷捞鱼到水桶中,搬到岸上。

所有的鱼被分在三个不同的桶里,便于识别和计数。运用彼得森淡水鱼导览手册进行学习和分类。在教授的帮助下,拿出一条鱼识别后,放入大桶中,并且记下每一种鱼的数量。这样有助于我们更好地了解沿河鱼类种群生存情况。

我们总共捕获了7个种类,158条淡水鱼,包括驼背太阳鱼,蓝腮太阳鱼,黄鲈,大口黑鲈,秀体底鳉等等。其中蓝腮太阳鱼数量最多,驼背太阳鱼其次,秀体底鳉比较罕见,只有1条。

表一 捕获鱼的分类统计

种名 捕获数
驼背太阳鱼 (Lepomis gibbosus) 38
蓝鳃太阳鱼 (Lepomis macrochirus) 90
黄鲈(Perca flavescens) 20
大嘴黑鲈 (Micropterus salmoides) 6
秀体底鲢 (Fundulus disphanous) 1
驼背太阳雨×蓝鳃太阳鱼杂交种 2
幼年欧鲢(Hybopsis) 1

我们通过观察鱼不同部位的特征来确定它们的种类。比如鱼的大小,背鳍,鳞片,颜色等等。驼背太阳鱼只有一片背鳍,身上有许多暗棕色粗线和橙色斑点。腮上也有标志性的亮红色、橙色斑点,周围有亮边。驼背太阳鱼沿河生长,可以适应低氧环境。蓝腮太阳鱼的样本数量最多,不是特别适应低氧环境,有时很难与驼背太阳鱼区分开。它背鳍的后缘有一个巨大的黑点,胸鳍很长到达眼底。腮旁有蓝条纹和黄白条纹。

我们也找到了几种不常见的鱼:黄鲈、大口黑鲈和秀体底鳉,它们在这片湖中较少。它们有着细长的躯体,绿色和褐色的条纹在银色的鱼线两侧。此外,我们也捕捉到了一条驼背太阳鱼和蓝腮太阳鱼的杂交品种,这种鱼在沿岸的湖水中大量存在。我们也捕捉到了一条幼年欧鲢,它非常小而且还没发育完全。

当我们确认了所有捕捉到的鱼的种类之后,我们把鱼放生到了湖水中。如果鱼长时间的离开湖水中,这对他们的生存也是十分不利的。我们把鱼放生到湖中后便步行回到了女王大学生物站。

午餐之后,我们听了王教授和Lougheed教授的两个演讲。第一个演讲是王教授关于湿地的介绍。王教授向我们展示了湿地定义和湿地的独特之处:一个是具有厌氧型土壤,另一个是由大型植物构成,例如:灌木、草丛、蕨类、苔藓植物等等。王教授还向我们介绍了五种不同的湿地类型:雨养泥炭沼泽、矿氧泥炭沼泽、木本植物沼泽、挺水植物沼泽和浅水沼泽五种,这几种不同的湿地类型具有不同的组成和不同的气候。湿地的水文条件对于植物的生长也起到了一定的作用。

第二个演讲是Lougheed教授讲述的在世界各地的以及安大略省的不同水生爬行类动物。他同样也讲到了不同类型爬行类动物的重要性,例如乌龟、鳄鱼、蜥蜴以及其他一些濒临灭绝的动物。这些动物是基本的物种,它们十分重要,其他物种的存在也取决与它们。一些爬行类动物的特征包括:有关爬行动物的一些特征包括:他们是变温动物,产羊膜卵,有些种类有颊窝可以用于红外感知。几乎所有种类都利用肺呼吸,不过有一些种类具有透气皮肤并可通过泄殖腔呼吸。爬行动物的一些代表包括:棱皮龟(Dermochelys coriacea),东方长颈恐龟(Chelodina longicollis),咸水鳄(Crocodylus porosus),北方水蛇(Nerodia sipdon)和海鬃蜥(Amblyrhynchus cristatus)事实上,爬行动物也面临着种族灭绝的危机。据生命行星指数统计,自1970年至今爬行动物已减少大约50%。

爬行类动物不仅对生态系统具有重要的作用,对我们来说也很重要。例如蛇可以捕食一些害虫。在其他方面,蛇也可以用作食物和皮革制品,蛇的毒液同样可以用作治疗的药物。因此,通过对爬行类动物的理解对其保护具有重要的作用。

晚餐之后,我们结束了一天对于湿地的评估工作。今天我们十分开心得到了这样的学习机会,今天的野外活动同样也充满了乐趣。

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