My Seaweed Looks Weird: An Introduction to Seaweed Parasites My Seaweed Looks Weird: An Introduction to Seaweed Parasites SAMS_3_1.0 My Seaweed Looks Weird: An Introduction to Seaweed Parasites This version of the content may include video, images and interactive content that may not be optimised for your device. Copyright © 2016 Scottish Association of Marine Sciences Intellectual property Except for third party materials and otherwise stated (see terms and conditions), this content is made available under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 Licence. Page 2 of 62 20th May 2016 http://www.open.edu/openlearnworks/course/view.php?id=2187 My Seaweed Looks Weird: An Introduction to Seaweed Parasites Contents Introduction 1 Getting started The structure of the course 2 Pathogens in ecosystems: naturally a key player 2.1 Parasites in ecological communities 2.2 Parasite, food webs and energy flows in aquatic ecosystems 2.3 Environmental impact of algal pathogens – Coccolithophores and their viruses 2.4 Summary of Section 2 3 Weird seaweeds in aquaculture facilities 3.1 Red algae: Diseases in Pyropia Farms 3.2 Red algae: Carrageenan and Agar 3.3 Kelps – brown algae 3.4 Emerging area of algae research: green algae … 3.5 Summary of Section 3 Conclusion Get involved References Acknowledgements Page 3 of 62 20th May 2016 http://www.open.edu/openlearnworks/course/view.php?id=2187 My Seaweed Looks Weird: An Introduction to Seaweed Parasites Introduction Like other living organisms, algae are affected by many pests and diseases which will result in abnormal morphological states or, more simply, weird- looking seaweeds. Though they remain vastly under-documented, parasites are increasingly regarded as key players in natural ecosystems, but also as one of the most serious economic and environmental threats to seaweed aquaculture. You should see this course as guiding your way through the research emerging within this field. The core content should take around 5 hours to work through. The further reading at the end of each section is entirely optional but will help you to extend and onsolidate your understanding. You will have the opportunity to test your understanding and gain a badge to recognise your learning through taking two quizzes. Before you attempt the quizzes, you should look at the Course and badge information page. Figure 1 A few ‘weird’ looking seaweeds: (a) Kappaphycus; (b) Ulva; (c) Pyropia that you will discover in this course. View description - Figure 1 A few ‘weird’ looking seaweeds: (a) Kappaphycus; (b) Ulva; (c) Pyropia that ... Page 4 of 62 20th May 2016 http://www.open.edu/openlearnworks/course/view.php?id=2187 My Seaweed Looks Weird: An Introduction to Seaweed Parasites 1 Getting started To start, watch the following video, which will give you a first look at pathogenic interaction. In the video, you will be introduced to Noreen Hiegle, who is a PhD candidate investigating the interaction between the pathogen Paraphysoderma sedebokorensis and the microalgae Haemmatococcus pluvialis. In the video she presents both organisms and illustrates the life cycle of the pathogen. Try to pick out the main stages and pay attention to the language used. There is a practice quiz about the video at the end of this section. Video content is not available in this format. Video 1 Illustration of a pathogenic life cycle. View transcript - Video 1 Illustration of a pathogenic life cycle. This short video illustrates the complexity of pathogenic life cycles, and highlights the fundamental steps required for a successful pathogen: recognition of the host, infection, reproduction and dispersion. Later in the course (in section 3.4.2), you will see what this pathogen really looks like. You will see in the next section that pests and pathogens of algae are highly diverse. So are their respective life cycles. This course does not aim to list all pathogens, but to illustrate some of them with respect to their ecological and economic importance. This course will generally deal with pathology concepts. We therefore strongly advise you to get comfortable with some important terminology. Here are some to start. Furthermore, as you go through the course you will see the terms are highlighted and you can click for an explanation or a quick reminder. Page 5 of 62 20th May 2016 http://www.open.edu/openlearnworks/course/view.php?id=2187 My Seaweed Looks Weird: An Introduction to Seaweed Parasites Introductory glossary Biotroph: An organism whose exclusive, natural growth environment is in or on living host cells. Disease: An abnormal physiological or developmental condition in a host due to the persistent action of a biotic (i.e. living organism) or abiotic (i.e. environmental) factor. Any condition of an organism that is economically detrimental. Epiphytism (Epiphytes): The association of an organism with the surface of a host. Facultative parasite: A facultative parasite is an organism that may resort to parasitic activity, but does not absolutely rely on any host for completion of its life cycle Hemibiotroph: A parasite that requires living host cells during part of its life cycle. Necrotroph: A pathogen that kills host cells in advance of its own growth, and obtains nutrients from the dead host cells. Obligate parasite: An organism that can only live as a parasite in nature. Parasite: An organism that obtains nutrients or other benefits from a living host. Note that a parasite may or may not cause disease. Pathogen: An organism that can cause disease. Pests: Anthropocentric term for all unwanted organisms interfering with the host (pathogens, parasites, epiphytes and grazers). Saprobe (saprotroph): An organism that feeds on dead or decaying organic matter. Symptoms: Visible or detectable characteristics of a disease. Page 6 of 62 20th May 2016 http://www.open.edu/openlearnworks/course/view.php?id=2187 My Seaweed Looks Weird: An Introduction to Seaweed Parasites Further reading Most of the above terms are adapted from the following phytopathology glossaries: Pathogenesis – concepts and definitions Plant pathology glossary It is worth browsing these resources to familiarise yourself with key terms. Learn more, test your knowledge If you take the time to read through the links below, you will see that algal parasites, as well as their ecological and economical relevance, are not – or only briefly – mentioned. This paucity of available information the motivation for creating these learning materials. This course does not focus on aquaculture, but on algal parasites in natural and farmed environments. For a more general description of seaweed aquaculture, you might be also interested by more general info on the basics and benefits of seaweed and microalgal farming: Seaweed farming on Wikipedia You might be interested in this article, which focuses on the Japanese Nori large-scale cultivation. You might like to read about the benefits typically associated with seaweed and microalgal cultivation. The structure of the course The rest of the course is divided into two main sections. The first section looks at the role of parasites in natural ecosystems, highlighting their importance within food webs and their wider environmental impact. The second section looks at parasites in seaweed aquaculture. It looks at the most widely researched and commercially important seaweeds and also touches on emerging areas highlighting significant gaps in our understanding of the dynamics within these systems. The language is necessarily technical, but will be familiar to people with a background in the biological sciences. We have tried not to assume too much prior knowledge of seaweeds or parasitology, and where possible we provide simplified summaries and explanations of key terms and interactions. For clarity and consistency, in this course we will mainly use the broader terms ‘diseases’ (irrespective of their biotic or abiotic origin) and ‘parasites’ (including pathogens, epiphytes and grazers.) Page 7 of 62 20th May 2016 http://www.open.edu/openlearnworks/course/view.php?id=2187 My Seaweed Looks Weird: An Introduction to Seaweed Parasites Seaweed (as you saw in the video and associated activities above) parasitology is a specialist and emerging area of research. This course will introduce you to this research, summarising and synthesising key studies. However, to appreciate this area you need to follow the links in the ‘Further reading’ boxes which are dotted about throughout the course. The core material in this course should take you around two to three hours to work through. The ‘Further reading’ will take longer, and you may get hooked Before you move on to Section 2, you should take the following short practice quiz, which is based on the video you watched in the previous section. Page 8 of 62 20th May 2016 http://www.open.edu/openlearnworks/course/view.php?id=2187 My Seaweed Looks Weird: An Introduction to Seaweed Parasites 2 Pathogens in ecosystems: naturally a key player In this section we aim to illustrate the ubiquity and natural occurrence of parasites as a grounding for the later section which looks specifically at algal pathology in aquaculture. You will start with looking at familiar terrestrial examples and then move on to look at aquatic examples on algal blooms, on parasites impact on food web and wider environmental processes. We have taken this approach as often when there is a spotlight on a disease it relates to its social or economic impact. 2.1 Parasites in ecological communities You will now explore the key role parasites play in ecosystems. 2.1.1 Parasites everywhere! Parasitic organisms exploit host resources for their development and reproduction. This lifestyle is successful, and it is widely recognised that there are more species of parasites than all non-parasite species combined. In aquatic ecosystems parasites can be found at each level of the food web, and in all taxonomic groups such as viruses, bacteria, fungi, oomycetes and so on.