Post by Art Goldsmith
(unless otherwise credited, photos by Art Goldsmith)
Field Course 2015: Effects of Human Development on Aquatic Environments and Biodiversity in Canada and China
World-Wide Fish Physiology and Ecology with Professor Wang AND Views from QUBS
Professor Yuxiang Wang and Fish Facts
On July 30, 2015, Professor Yuxiang Wang presented his lecture on Fish Biodiversity/Physiology and Conservation. The slide presentation roamed the globe through Yuxiang’s eyes, to many of the most diverse and least diverse ecosystems. His breadth and depth of observation, analysis and research kept the students and me in maximum learning mode.
The assembled class put down their cell phones and looked their very best for this photo, as they awaited Professor Wang.
The basics and fish facts are required to understand the more detailed knowledge imparted on us later in the session.
Any excellent introductory course will inform participants about the big picture. The slides above and below answer the questions: How many kinds of fish are there and where did they come from? Fish are indeed vertebrates, animals with backbones, just like us and the other mammals, birds, reptiles and amphibians. And there are lots and lots of different kinds of fish.
Canada’s record on marine and freshwater conservation isn’t the brightest, with less than 1% of our oceans under any kind of protection, and that protection is very minimal, as resource industries still take priority even in our marine parks. Australia, for contrast, has managed to protect 38% of its surrounding marine space. When I saw Professor Wang’s slide above, it reminded me of the quest to save diversity among species, since diversity is the underpinning of a healthy biosphere.
I recall visiting Biscayne National Park in Florida, USA, where one of the pamphlets proclaimed that there were more fish species in this national marine park than all the vertebrates in Colorado put together. These fish species require a healthy shoreline wetland environment and unpolluted water to persist. Biscayne National Park also has a large coral reef, another important and stressed element for marine ecology globally.
Evolutionary biology and the origins of fish are subjects that require large volumes to achieve basic understanding. Yiuxang’s slide is a great summary. Note the exclusions from generalities about fish (lamprey and hagfish). The lamprey is of special interest for me, as it was one of the first alien species to reach our Great Lakes and St. Lawrence River, threatening an already stressed fishery. Having not focused on this species in decades, Yiuxiang provided a good summary of recent developments regarding attempts to control the Sea Lamprey, (Petromyzon marinus). Of special note, the lamprey is native to the North Atlantic. It is anadromous (more later) and could reach the Gulf of St. Lawrence. The St. Lawrence Seaway project of the1950s provided convenient routes around rapids and falls, yielding a fresh supply of fish to larval lamprey throughout the St. Lawrence and Great Lakes.
Hagfish and Lampreys
The Jawless fish kicked (hard to do without feet!) things off, specifically, Hagfish and Lampreys.
The 60 species of Hagfish with rudimentary eyes live in hypoxic habitats (low oxygen) with little light (i.e., they may live in ocean depths). Here are a few more facts about Hagfish from U.C. Berkeley:
“The adjective which best describes the Myxini is “Lovecraftian”. Hagfish are long, slender and pinkish, and are best known for the large quantities of sticky slime which they produce. Hagfish have three accessory hearts, no cerebrum or cerebellum, no jaws or stomach, and will “sneeze” when their nostrils clog with their own slime. They are found in cold ocean waters of both hemispheres, scavenging dead and dying fish but also preying on small invertebrates.
Hagfish are almost blind, but have well developed senses of touch and smell. They have four pairs of sensing tentacles arranged around their mouth. The mouth lacks jaws, but a Hagfish is equipped with two pairs of tooth-like rasps on the top of a tongue-like projection. As this tongue is pulled back into the Hagfish’s mouth, the pairs of rasps pinch together. This bite is used to tear into the flesh of dead and dying fish which have sunk to the muddy ocean bottom, or in catching and eating marine invertebrates. By far, the largest part of their diet is polychaete worms. Due to their slow metabolism, Hagfish may go for up to seven months without eating any food.”
Or you can read all of the facts here.
I bet the creature in the “Alien” movies was based on the hagfish and lamprey.
Their “vertebrate” status has also become compromised through adaptive evolution, as their spinal column is vestigial (no vertebrae) with a partial cranium. There are hagfish in the Gulf Islands off Vancouver.
Instead of tooth-like Hagfish rasps, the lamprey’s mouth evolved suctorial disc teeth. The front end of a lamprey is a sight, looking more like a sanding disk with its circular array of inward pointing teeth. They do not have the paired fins of most other fish. Indeed, like the hagfish, lampreys attach themselves to a fish, rasping away flesh using the “buzzsaw” mouth. Ouch! They are also anadromous. Like Atlantic Salmon, the adults spawn and develop in freshwater and then return to saltwater to live. Larvae live buried in freshwater systems. Biologists applied their knowledge of the lamprey to control it. Lamprey use chemo-sensing, rather than sight, to manoeuvre through their habitat. Like many insects, they use pheromones to find each other for breeding. Dr. Lee, at Michigan State University, used this knowledge to attract males, which were then sterilized. Returning to the environment to mate, these males, of course, produce no offspring, reducing (not eliminating) populations. This application of biology is much more refined, effective, economical and environmentally benign than the first approach to control: chemicals, which kill much more than the target species. The photo above, from Yuxiang’s presentation shows a lamprey attached to and feeding on a Lake Trout. The lowest photo in the slide shows the mouth of the lamprey.
Now that we have dealt with the exceptions, let’s survey the rule—the bony fish.
Cartilaginous and Bony Fish
The sharks and rays are classified in a separate group (Class Chondrichhyes), which are considered to be older than other jawed fish on the evolutionary scale. The Holocephali (Ratfish and cousins) are less well-known deep-water living marine fish.
The bony fishes (Class Osteichthyes), are the rest of the fish species and the most familiar to us. Avid fishers know well the species that respond to our lures and bait. There are so many more. One of the more illustrious species, the Coelacanth, a living fossil (It was thought to have become extinct 80 million years ago. Oh well, science does learn from mistakes!) was featured prominently in my McGill University education in the late 1960s.
The discovery of the Coelacanth has filled in answers to evolutionary questions about the evolution of bony fish and the tetrapods (those of us with legs).
This brief background led Yuxiang into the meat and potatoes (or fish and chips?) portion of his presentation: adaptive and ecological physiology of fish.
Teleosts are any member of a large and extremely diverse group of ray-finned fish. Along with the chondrosteans and the holosteans, they are one of the three major subdivisions of the class Actinopterygii, the most advanced of the bony fishes. The teleosts include virtually all the world’s important sport and commercial fishes, as well as a much larger number of lesser-known species. When the average person thinks about fish, he/she usually has a teleost in mind.
The slide above describes how fish have adapted structurally and functionally to their environment. The following terms are important to understanding fish physiology in some of the more extreme habitats studied by Professor Wang. The slide below maps out typical teleost body parts.
Ammonotelic refers to a fish that excrete nitrogenous waste derived from amino-acid catabolism in the form of ammonia.
Poikilotherm refers to an organism that cannot regulate its body temperature except by behavioural means, such as basking or burrowing.
We hear daily about increasing pressure on our marine and freshwater species. Fish are staples of the human diet. Therefore, conservation would logically move to the top of our global “to do” list. That isn’t the case, and research like that of Professor Wang’s aids those of us with the motivation to act and provides us with the evidence needed for change. Of course, the Queen’s University Biological Station (QUBS) is a key resource for freshwater fisheries research. Researchers come from all over North America to study the fish in Lake Opinicon and other surrounding lakes. There are also lakes wholly contained within the QUBS properties, making them ideal for whole lake research. Lake Opinicon’s shore houses the QUBS facilities. It is quite a diverse lake. In fact it is a bit more diverse than the list given in the slide below. The two fish pictured in the slide are two other very common Centrarchidae, the Blue Gill (Lepomis macrochirus), and Pumpkinseed (Lepomis gibbosus) Sunfish. These two fish are often the first fish a child fisher may catch in our area. There is a Centrarchidae missing: the Black Crappie, (Pomoxis nigromaculatus) seen in the photo beside “Fish in Lake Opinicon”. Those are Gregory Bulte’s hands briefly showing the fish to his class this summer at QUBS. Look for another edition of this blog featuring Grégory Bulté’s Ecology Field Course.
Onward to Professor Wang’s research, which focuses on fish physiology and ecology. Back in my student days, the term physiology caused me to shudder and run. If only Yuxiang Wang’s approach had been available back then. He made a clear and easy-to-understand connection between physiology and ecology. Also, he makes a good case for this kind of study to better understand fish which are important to the health and well being of local people. I especially appreciate the non-laboratory approaches that Wang takes. He gets to know and to study his fish on site in some of the more interesting places on Earth.
Who wouldn’t call Amazon waters “amazing”? Some of Professor Wang’s work is done at the confluence of two main Amazon tributaries— the Rio Solimoes and the Rio Negro— at Manaus, Brazil. Professor Wang is telling us, by pointing at the water chemistry slide, to look at the amazing water chemistry differences between the two.
The Rio Negro’s black waters are a result of their origin in the mineral poor tropical rainforests of northwestern Brazil. Alternatively, the Rio Solimoes originates in the Andes and covers a great deal more distance than the Rio Negro. Therefore, its waters are mineral rich. The Rio Negro is acidic, much like our boreal rivers that carry heavy loads of carbonic acid, while Rio Solimoes water is almost neutral. As its name implies, the waters of the Rio Negro are very black when seen from aerial or satellite views, whereas those of the Rio Solimoes are muddy and creamy looking from the same views. Even after the rivers come together, you can see these colour differences far downstream. Of course these differences mean that fish living in each river are adapting to these very different conditions. Therefore, this is an ideal spot for comparative fish physiology.
From the category “I did not KNOW that!” Yuxiang tells us that the intense flow of the Amazon River pushes its fresh water 300 kms out to sea in the South Atlantic. Ships crossing this band of fresh water would sink if they were too heavily laden, due to the drop in buoyancy crossing from salt to Amazon River water.
The Pirarucu (Arapaima gigas), shown above, grows to enormous sizes in the challenging Amazon waters. Like most fish, (tuna and billfish are exceptions), Pirarucu are poikilotherms, that is their body temperatures change with environmental temperature changes. Since water has a high heat capacity, much higher than air, poikilotherms have less of a challenge in water than terrestrial vertebrates. This gigantic Amazon fish adapts in many ways. In the very warm oxygen-poor waters of the Amazon, Pirarucu breathe air using an adapted swim bladder. Another extraordinary adaptation is the Pirarucu kidney. Most animals need a way to excrete nitrogen, a necessary by-product of body waste management. Birds, reptiles and insects excrete uric acid, and mammals excrete urea. These latter biochemicals avoid the toxicity of the simpler nitrogen compound, ammonia. Therefore, it is astonishing to learn that the Pirarucu is ammonotelic, excreting ammonia. The warm Amazon waters do lack oxygen, and daily oxygen and temperature fluctuations may also be great.
The Oscar (Astronotus oscellatus), pictured below, is highly adapted to avoiding hypercapnia, excessive carbon dioxide in the bloodstream, typically caused by inadequate respiration.
Just for fun: did you know that teleosts make up such a large part of the oceans’ biomass that their “poop” maintains the pH of the waters, regulating acid-base levels.
To China we go…. Professor Wang has conducted ongoing research at the remarkable Lake Qinghai, a very large lake on the cold, dry north central plain of China. Recent socioeconomic developments and internal migration have changed the local human population culture. The original inhabitants have great respect for the lake and its formally teeming fish species, the Naked Carp (Gymnocypris przewalski). The newly arrived inhabitants have decided to develop irrigation-based agriculture in the lands around the lake, which has resulted in a 10-12 cm drop per year in lake levels. The pH of the lake is 9.4 (very basic), and it has a high Magnesium and low Calcium concentration. When lake volume decreases, salinity increases, putting the animals adapted to the natural pH at risk. You may read about the lake’s story in the work cited in the slide below (Wood et al.) and by following up with Professor Wang’s research.
The next slide cites “Wood et al” and their work on how the carp have adapted to the rapid (only 50 years) decline in Lake Qinghai water volumes and increased salinity. Wang’s work has shown that much needs to be done to protect the lake and its biological community, as imbalances threaten its most vulnerable rare species.
The students also had many field opportunities during their two weeks in Canada. They toured the Thousand Islands and the Kingston sewage treatment plant. They went to Parliament Hill in Ottawa and then, very central to any Canadian biologist’s bucket list, visited the collections of the Canadian Museum of Nature in Aylmer, Quebec. Thanks to Team Round-headed Apple Borer and to Mark Szenteczki for the following photos:
Thanks to the students and Mark, and these two course creators,producers, directors and stars. We will see you in China for this course next year!
Tree Swallows research is the next topic, and look for stories and photos featuring Professor Raleigh Robertson, the long-time Director of QUBS, who started Tree Swallow research at Queen’s in the 1970s. Also, some photos of QUBS will be featured.