July 31, 2017
Today was a day dedicated to learning about fish, and the local species. We began with a short presentation by Dr. Barry Madison and Courtney our TA that the ubiquitous term, ‘fish’, cannot strictly be used to refer to scaled animals that live and breathe in water. For example, the African lungfish (genus Protopterus) can breathe air for a substantial period of time. What we can do is classify fish into three major classes: the Agnathans (jawless fish), Chondrichthyans (cartilaginous fish) and Teleosts (bony fish). Teleost fish are incredibly species diverse that range in size at sexual maturity from 2 cm (family Percidae) to 2m (family Acipenseridae). Selection regimes across diverse environment underlies the immense range of forms and behaviours of fish species. As an extreme example, the hadal snailfish (Pseudoliparis amblystomopsis) is found in the Marianas Trench, which reaches a maximum depth of almost 11 kms, and is able to survive in this abyss despite the low light levels, low oxygen concentrations in the water, and low temperature.
今天早上,Dr. Barry Madison 和 Courtney 为我们准备了有关鱼类的讲座。我们了解到,“鱼”并不仅局 限于那些生活在水中长有鳞片的动物。例如,非洲肺鱼(African lungfish)能在空气中呼吸很长的时 间。鱼类可以分成三个纲:无颌总纲(the Agnathans),软骨鱼纲(the Chondrichthyans)和真骨 鱼纲(the Teleosts)。有些鱼类只有 2cm(河鲈科,family Percidae),而有些可以长到 2m 长(鲟 科,family Acipenseridae)。环境迫使许多鱼类物种适应某些特殊的环境。例如,发现于马里亚纳海 沟的拟狮子鱼(Pseudoliparis amblystomopsis),能够在近乎无光、低氧而又寒冷的海底深渊中生 活。
On a regional scale (e.g. Eastern Ontario) and at QUBS, we can find species from the Cypriniformes (minnows, dace, shiners), the Cyprinodontiformes (killifishes and live-bearers) and the Perciformes (sunfish). Today, we did some seining to capture some local fish species and learn some of their key features and ecology. We caught only the centrarchids – Pumpkinseed (Lepomis gibbosus) and Bluegill fish (Lepomis macrochirus). These species are nest-builders, are sexually dimorphic, have overlapping aquatic habitats and niches, and are known to hybridize on occasiona. However, bluegills prefer to spawn at a temperature of 19°C while pumpkinseed prefer to spawn at cooler temperatures averaging of 13°C. Mature pumpkinseeds are known for the distinctive orange spots on their opercula and lighter orange spots distributed evenly over their bodies. Mature bluegills do not have these distinctive orange-spotted opercula and their deep bodies have striped patterns.
在QUBS 这个地方,我们能发现鲤形目(the Cypriniformes)的鲰鱼(minnows)、鲦鱼(dace)和shiners,鳉形目(the Cyprinodontiformes)的鳉鱼(killifish),鲈形目(the Perciformes)的太阳鱼(sunfish)。今天上午讲座后,我们到周边的一个湖岸进行了围网捕鱼,对鱼类进行鉴定与评估。不过,我们今天只抓到了太阳鱼科的瓜仁太阳鱼(pumpkinseed, Lepomis gibbosus)和蓝鳃太阳鱼(bluegill,Lepomis macrochirus)。这两种太阳鱼都会筑巢,并且具有雌雄二型性,他们生态位有重叠,种间杂交常见。然而,蓝鳃太阳鱼更喜欢在19 度的水温中产卵,而瓜仁太阳鱼更喜欢13 度。另外,成年的瓜仁太阳鱼的鳃盖处有橘黄色斑块,并且全身遍布橘黄色点。成年的蓝鳃太阳鱼没有橘黄色斑块,并且它们的身体两侧有垂直的条纹。
Seining is an active form of non-lethal fishing. As our seine net was quite small, only two individuals were required to deploy it. Initially holding the net parallel to the shore, the individuals hold onto the poles at the ends of the net and gradually move the poles towards each other in gentle up-and-down movements so that the net eventually is turned perpendicular to the shoreline. Critical for successful seining, the poles must not be lifted of the lake bottom to ensure that no fish escape under the lead line at the base of the net. The lead line keeps seine net close to the lake sediment and the float line at the top of the net ensures that net is upright and stretched out in the water to catch the maximum number of fish. Once the fishers face the shore, and come into proximity with one another, they flip the net horizontally so that the fish are trapped in the ‘purse’ of the net. The fish are removed and placed in buckets filled with lake water to hold them so that they may be individually assessed by sex, mass (grams), and length (millimetres). The buckets must continually be replenished with lake water so that there is enough oxygen in the water for fish to breathe and so that waste in the form of ammonia does not accumulate. Water pH and air and water temperature across seining events were also assessed to relate fish conditions to their environment; geographic coordinates and elevation was measured only once.
围网是一种非致死性的捕鱼技术。由于我们的网太小,只需要两个人就可以操作。围网开始时,一个人拿着网一端的杆子站着不动,另一个人拿着另一端向远处撑开网,然后以圆弧状向内缓慢移动,网由垂直逐渐变为平行于河岸。你可以看见鱼群逐渐被驱赶到河岸处,并进入网中。围网时,一定不要把网的下方抬起,不然鱼可能会跑走。网下方的锤条能使网下沉。网平行后,两端的人都缓慢把杆子倒下使渔网朝上,这时鱼都到了网的上方,然后把绳子卷起就能把鱼留在网中。抓到的鱼被装进有水的桶中,我们逐一测量它们的长度与体重。桶里的鱼必需要持续供给新的湖水或氧气以保证鱼儿不会因缺氧而死亡。湖和桶中水的pH、气体以及温度都进行了持续检测。

Group 6 seining for the first time/ 第六組圍網首次。

Junchen is old enough to play with the water by himself/ 鄧俊臣是一個喜歡自己玩水的大男 孩。

Barry Madison teaching Prama how to seine properly/巴里麥迪遜教授指导普拉馬如何正確圍 網。

A Bluegill (Lepomis macrochirus)/ 蓝鳃太阳鱼.
Later in the afternoon, we studied the external and internal anatomy of fish. Each group was given a fish and we used this to learn how to identify the nares, the eyes, mouth, operculum, spiny dorsal fin, soft dorsal fin, pectoral fins, pelvic fins, anal fin, scales, lateral line, caudal fin, the peduncle (narrow part of the body where the tail attaches), and the vent. The appearance and structure of these features are often unique to particular fish species. For example, bluegill and sunfish have a relatively unnotched and continuous spiny dorsal fin with a soft dorsal fin, while the largemouth bass (Micropterus salmoides) has a quite notched and disconnected spiny dorsal fin and soft dorsal fin.
之后的下午,我们对两种鱼类进行了体外及体内的解剖研究。老师给我们每两人一条鱼。先从体外开始,我们观察了鱼的各个部分(鼻孔、眼睛、侧线、鳃盖,等),某些鱼类的这些外形特征是分类的重要依据。例如,蓝鳃太阳鱼有相对无缺口和连续的背鳍,而大口鲈鱼(Micropterus salmoides)的背鳍有明显缺口并不连续。
We also dissected our respective fish to determine its sex, collect the guts for future gut content analysis, and quantify its using otoliths (hard, calcium carbonate structures located directly behind the brain of bony fishes). We identified the 2-chamber hearts, the gills, the brain (composed of the olfactory bulb, telencephalon, optic tectum, and cerebellum), the liver (with spots that may indicate parasites), the stomach, intestines with pyloric caeca, the bladder, swim bladder, the spleen, and the gall bladder. The spleen of our pumpkinseed was unexpectedly black possibly indicating some previous bout of stress. We saved the alimentary tract for trophic ecology analysis.
在体外解剖观察后,我们开始正式的解剖工作。我们鉴定了鱼类的性别、胃内容物成分,并通过看耳石(otoliths)预测鱼类年龄。我们观察了鱼类两心室的心脏、鳃、脑(包括嗅球、大脑、小脑等)。这条鱼的肝上有一些白点,这可能意味着寄生虫感染。我们还看了幽门盲囊、鱼鳔、脾脏等器官。我们这只鱼的脾脏很黑,可能说明它生前受到的环境压力很大。鱼的肠道也被切下放入皿中,进行食性及营养级检测。

Barry Madison educating us on the anatomy of fish/巴里麦迪逊教我们解剖鱼.
Courtney helped us to cut into the cranial region of the fish to locate the otoliths. As we mentioned above, otoliths are two calcium carbonate ear bones found in every fish. These are used for equilibrium and balance because they are sensitive to gravity and linear acceleration. Removing otoliths is a highly invasive procedure that thus cannot be done online fish, and thus is typically performed on fish that have been sacrificed. Otoliths have an ‘origin’ and with every season of growth develop annuli (rings). The distances between annuli are not always consistent, or even because they reflect the overall growth of the individual (e.g. fish typically grow more during less stressful seasons like summer). Scales can also be used for determining the age of the fish. However, unlike otoliths, if some scales are removed they grow back with the year of the old scale’s removal represented as the origin. This may lead to spurious assertions of age and thus otoliths are the more robust way to assess fish age. Our fish had five annuli on its otoliths implying five seasons of growth.
解剖过程中,Courtney 帮助我们取得了耳石。耳石成分是碳酸钙,一共有二个,位于鱼类脑后端基部,起 维持平衡的作用。取出耳石会导致鱼类死亡,而耳石上的纹路能反映鱼类年龄(发育)。两条纹路间的距离不总是相等的,鱼类在不同环境压力下,生长速率会改变。鳞片也能够对年龄进行预测。然而,有些鳞片被移除后又会长出新的,用鳞片预测年龄可能不准确。所以,耳石可能是最准确用来预测年龄的工具。我们解剖的这条鱼有5 条纹路,说明它年龄大概是5 岁。

Otoliths of five-year olf viewed under a microscope/ 在显微镜下观看耳石。
After dinner, we went outside and Dr. Mingzhi Qi introduced us to unmanned aerial vehicles (U.A.V.). These U.A.V. are commonly known as drones and are often used for military purposes. However, in biology, they are very useful because a researcher may not need to survey the land directly when they have U.A.V. may do so more efficiently. The U.A.V. takes aerial photos for researchers from elevations that may get to 1 km above the ground. U.A.V. can be really handy as their cameras may be mounted on gimbals that allow stabilization and have controllers that may be used during emergencies. U.A.V. are so cool; we must purchase our own!
在晚饭后,Dr. Mingzhi 向我们介绍了U.A.V(unmanned aerial vehicles),这是一种无人机,可用于军事活动,但它在生物方面也有很多用处,如土地检测等。无人机可以最高从1000m 的高处拍摄照片。这种无人机很方便,因为它的相机是自稳定的,并且有一个控制装置以便在紧急时刻强制控制飞机。U.A.V 真的很酷;我们都想买一架了!

Image from an unmanned aerial vehicle (U.A.V)/ 来自无人机的图像
Love,
Prama, Junchen, Jiayi, and Tian tian
普拉玛,邓俊辰,吴嘉屹,赵天天