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Zooxanthellae Expelled from Bleached Corals at 33°C Are
MARINE ECOLOGY PROGRESS SERIES Vol. 220: 163–168, 2001 Published September 27 Mar Ecol Prog Ser Zooxanthellae expelled from bleached corals at 33؇C are photosynthetically competent Peter J. Ralph1,*, Rolf Gademann2, Anthony W. D. Larkum3 1Department of Environmental Sciences, University of Technology, PO Box 123 Broadway, Sydney, New South Wales 2065, Australia 2Gademann Messtechnik, Würzburg, Germany 3School of Biological Sciences (A08), University of Sydney, New South Wales 2006, Australia ABSTRACT: While a number of factors have been linked to coral bleaching, such as high light, high temperature, low salinity, and UV exposure, the best explanation for recent coral bleaching events are small temperature excursions of 1 to 2°C above summer sea-surface temperatures in the tropics which induce the dinoflagellate symbionts (zooxanthellae) to be expelled from the host. The mecha- nism that triggers this expulsion of the algal symbionts is not resolved, but has been attributed to damage to the photosynthetic mechanism of the zooxanthellae. In the present investigation we addressed the question of whether such expelled zooxanthellae are indeed impaired irreversibly in their photosynthesis. We employed a Microscopy Pulse Amplitude-Modulated (PAM) fluorometer, by which individual zooxanthellae can be examined to study photosynthesis in zooxanthellae expelled when corals are subjected to a temperature of 33°C. We show that the expelled zooxanthellae from Cyphastrea serailia were largely unaffected in their photosynthesis and could be heated to 37°C before showing temperature-induced photosynthetic impairment. These results suggest strongly that the early events that trigger temperature-induced expulsion of zooxanthellae involve a dysfunction in the interaction of the zooxanthellae and the coral host tissue, and not a dysfunction in the zooxan- thellae per se. -
The Polyp and the Medusa Life on the Move
The Polyp and the Medusa Life on the Move Millions of years ago, unlikely pioneers sparked a revolution. Cnidarians set animal life in motion. So much of what we take for granted today began with Cnidarians. FROM SHAPE OF LIFE The Polyp and the Medusa Life on the Move Take a moment to follow these instructions: Raise your right hand in front of your eyes. Make a fist. Make the peace sign with your first and second fingers. Make a fist again. Open your hand. Read the next paragraph. What you just did was exhibit a trait we associate with all animals, a trait called, quite simply, movement. And not only did you just move your hand, but you moved it after passing the idea of movement through your brain and nerve cells to command the muscles in your hand to obey. To do this, your body needs muscles to move and nerves to transmit and coordinate movement, whether voluntary or involuntary. The bit of business involved in making fists and peace signs is pretty complex behavior, but it pales by comparison with the suites of thought and movement associated with throwing a curve ball, walking, swimming, dancing, breathing, landing an airplane, running down prey, or fleeing a predator. But whether by thought or instinct, you and all animals except sponges have the ability to move and to carry out complex sequences of movement called behavior. In fact, movement is such a basic part of being an animal that we tend to define animalness as having the ability to move and behave. -
Zooxanthellae) ROB ROWAN* and DENNIS A
Proc. Natl. Acad. Sci. USA Vol. 89, pp. 3639-3643, April 1992 Plant Biology Ribosomal RNA sequences and the diversity of symbiotic dinoflagellates (zooxanthellae) ROB ROWAN* AND DENNIS A. POWERS Department of Biological Sciences, Stanford University, Hopkins Marine Station, Pacific Grove, CA 93950-3094 Communicated by Winslow R. Briggs, December 23, 1991 ABSTRACT Zooxanthellae are unicellular algae that oc- systematics can be obviated by applying molecular methods. cur as endosymbionts in many hundreds of common marine DNA sequences are excellent phylogenetic data (for reviews, invertebrates. The issue of zooxanthella diversity has been see refs. 15 and 16) that are especially useful for identifying difficult to address. Most zooxanthellae have been placed in the and classifying morphologically depauperate organisms like dinoflagellate genus Symbiodinium as one or several species that zooxanthellae. Furthermore, Symbiodinium genes can be are not easily distinguished. We compared Symbiodinium and obtained from intact symbioses using the polymerase chain nonsymbiotic dinoflageliates using small ribosomal subunit reaction (PCR; ref. 17), removing the obstacle of culturing RNA sequences. Surprisingly, small ribosomal subunit RNA zooxanthellae for the purpose of taxonomy (18). diversity within the genus Symbiodinium is comparable to that Various DNA sequences evolve at very different rates; observed among different orders of nonsymbiotic dinoflagel- which sequences are informative for a group depends upon lates. These data reinforce the conclusion that Symbiodinium- how closely related its members are. Having no a priori like zooxanthellae represent a collection of distinct species and information for Symbiodinium, we examined nuclear genes provide a precedent for a molecular genetic taxonomy of the that encode small ribosomal subunit RNA (ssRNA; 16S-like genus Symbiodinium. -
Cassiopea Xamachana (Upside-Down Jellyfish)
UWI The Online Guide to the Animals of Trinidad and Tobago Ecology Cassiopea xamachana (Upside-down Jellyfish) Order: Rhizostomeae (Eight-armed Jellyfish) Class: Scyphozoa (Jellyfish) Phylum: Cnidaria (Corals, Sea Anemones and Jellyfish) Fig. 1. Upside-down jellyfish, Cassiopea xamachana. [http://images.fineartamerica.com/images-medium-large/upside-down-jellyfish-cassiopea-sp-pete-oxford.jpg, downloaded 9 March 2016] TRAITS. Cassiopea xamachana, also known as the upside-down jellyfish, is quite large with a dominant medusa (adult jellyfish phase) about 30cm in diameter (Encyclopaedia of Life, 2014), resembling more of a sea anemone than a typical jellyfish. The name is associated with the fact that the umbrella (bell-shaped part) settles on the bottom of the sea floor while its frilly tentacles face upwards (Fig. 1). The saucer-shaped umbrella is relatively flat with a well-defined central depression on the upper surface (exumbrella), the side opposite the tentacles (Berryman, 2016). This depression gives the jellyfish the ability to stick to the bottom of the sea floor while it pulsates gently, via a suction action. There are eight oral arms (tentacles) around the mouth, branched elaborately in four pairs. The most commonly seen colour is a greenish grey-blue, due to the presence of zooxanthellae (algae) embedded in the mesoglea (jelly) of the body, and especially the arms. The mobile medusa stage is dioecious, which means that there are separate males and females, although there are no features which distinguish the sexes. The polyp stage is sessile (fixed to the substrate) and small (Sterrer, 1986). UWI The Online Guide to the Animals of Trinidad and Tobago Ecology DISTRIBUTION. -
PROGRAMME ABSTRACTS AGM Papers
The Palaeontological Association 63rd Annual Meeting 15th–21st December 2019 University of Valencia, Spain PROGRAMME ABSTRACTS AGM papers Palaeontological Association 6 ANNUAL MEETING ANNUAL MEETING Palaeontological Association 1 The Palaeontological Association 63rd Annual Meeting 15th–21st December 2019 University of Valencia The programme and abstracts for the 63rd Annual Meeting of the Palaeontological Association are provided after the following information and summary of the meeting. An easy-to-navigate pocket guide to the Meeting is also available to delegates. Venue The Annual Meeting will take place in the faculties of Philosophy and Philology on the Blasco Ibañez Campus of the University of Valencia. The Symposium will take place in the Salon Actos Manuel Sanchis Guarner in the Faculty of Philology. The main meeting will take place in this and a nearby lecture theatre (Salon Actos, Faculty of Philosophy). There is a Metro stop just a few metres from the campus that connects with the centre of the city in 5-10 minutes (Line 3-Facultats). Alternatively, the campus is a 20-25 minute walk from the ‘old town’. Registration Registration will be possible before and during the Symposium at the entrance to the Salon Actos in the Faculty of Philosophy. During the main meeting the registration desk will continue to be available in the Faculty of Philosophy. Oral Presentations All speakers (apart from the symposium speakers) have been allocated 15 minutes. It is therefore expected that you prepare to speak for no more than 12 minutes to allow time for questions and switching between presenters. We have a number of parallel sessions in nearby lecture theatres so timing will be especially important. -
The Genetic Identity of Dinoflagellate Symbionts in Caribbean Octocorals
Coral Reefs (2004) 23: 465-472 DOI 10.1007/S00338-004-0408-8 REPORT Tamar L. Goulet • Mary Alice CofFroth The genetic identity of dinoflagellate symbionts in Caribbean octocorals Received: 2 September 2002 / Accepted: 20 December 2003 / Published online: 29 July 2004 © Springer-Verlag 2004 Abstract Many cnidarians (e.g., corals, octocorals, sea Introduction anemones) maintain a symbiosis with dinoflagellates (zooxanthellae). Zooxanthellae are grouped into The cornerstone of the coral reef ecosystem is the sym- clades, with studies focusing on scleractinian corals. biosis between cnidarians (e.g., corals, octocorals, sea We characterized zooxanthellae in 35 species of Caribbean octocorals. Most Caribbean octocoral spe- anemones) and unicellular dinoñagellates commonly called zooxanthellae. Studies of zooxanthella symbioses cies (88.6%) hosted clade B zooxanthellae, 8.6% have previously been hampered by the difficulty of hosted clade C, and one species (2.9%) hosted clades B and C. Erythropodium caribaeorum harbored clade identifying the algae. Past techniques relied on culturing and/or identifying zooxanthellae based on their free- C and a unique RFLP pattern, which, when se- swimming form (Trench 1997), antigenic features quenced, fell within clade C. Five octocoral species (Kinzie and Chee 1982), and cell architecture (Blank displayed no zooxanthella cladal variation with depth. 1987), among others. These techniques were time-con- Nine of the ten octocoral species sampled throughout suming, required a great deal of expertise, and resulted the Caribbean exhibited no regional zooxanthella cla- in the differentiation of only a small number of zoo- dal differences. The exception, Briareum asbestinum, xanthella species. Molecular techniques amplifying had some colonies from the Dry Tortugas exhibiting zooxanthella DNA encoding for the small and large the E. -
Coral Histopathology II
INTRODUCTION The prevalence and severity of reef degradation due to coral disease has increased considerably over the last two decades. Emerging coral diseases have been linked to biotic and abiotic stressors and their synergistic interactions. Coral disease research is in its infancy and only beginning to take advantage of technologies and methodologies routinely used in epizootiology, clinical and diagnostic medicine, and pathology. This Coral Histopathology Workshop (and its predecessor) provided forums to begin adapting advances in biomedical and veterinary sciences, pathology, toxicology, and biotechnology to the study of coral disease and health; it also provided a foundation on which to build a framework for coral disease research that can interface with mainstream medical and veterinary research. The goals of this Workshop were to produce standards for (1) morphological descriptors based on accepted medical terminology, (2) consistent and concise descriptions of lesions in the field, as well as (3) clinical morphological diagnoses in the laboratory. Consensus reached during this workshop will be peer reviewed by the coral scientific community, both in public settings where the materials will be presented in workshop/discussion formats, directly soliciting review by others establishing terminology for the field, and through opinion papers in the peer-review literature to adopt specialized terminologies to facilitate communication among histopathologists. Once adopted, the terminology and microscopic descriptions will enable development of instructional materials and distance learning tools for coral histopathology. STUDY SETS OF HISTOLOGY SLIDES PROVIDED BY THE IRCP An important facet of this workshop was the use of study sets of slides with serial sections from the same sample for independent individual micro- E. -
Feeding-Dependent Tentacle Development in the Sea Anemone Nematostella Vectensis ✉ Aissam Ikmi 1,2 , Petrus J
ARTICLE https://doi.org/10.1038/s41467-020-18133-0 OPEN Feeding-dependent tentacle development in the sea anemone Nematostella vectensis ✉ Aissam Ikmi 1,2 , Petrus J. Steenbergen1, Marie Anzo 1, Mason R. McMullen2,3, Anniek Stokkermans1, Lacey R. Ellington2 & Matthew C. Gibson2,4 In cnidarians, axial patterning is not restricted to embryogenesis but continues throughout a prolonged life history filled with unpredictable environmental changes. How this develop- 1234567890():,; mental capacity copes with fluctuations of food availability and whether it recapitulates embryonic mechanisms remain poorly understood. Here we utilize the tentacles of the sea anemone Nematostella vectensis as an experimental paradigm for developmental patterning across distinct life history stages. By analyzing over 1000 growing polyps, we find that tentacle progression is stereotyped and occurs in a feeding-dependent manner. Using a combination of genetic, cellular and molecular approaches, we demonstrate that the crosstalk between Target of Rapamycin (TOR) and Fibroblast growth factor receptor b (Fgfrb) signaling in ring muscles defines tentacle primordia in fed polyps. Interestingly, Fgfrb-dependent polarized growth is observed in polyp but not embryonic tentacle primordia. These findings show an unexpected plasticity of tentacle development, and link post-embryonic body patterning with food availability. 1 Developmental Biology Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany. 2 Stowers Institute for Medical Research, Kansas City, MO 64110, -
Zooxanthellae Regulation in Yellow Blotch/Band and Other Coral Diseases Contrasted with Temperature Related Bleaching: in Situ Destruction Vs Expulsion
Symbiosis, 37 (2004) 63–85 63 Balaban, Philadelphia/Rehovot Zooxanthellae Regulation in Yellow Blotch/Band and Other Coral Diseases Contrasted with Temperature Related Bleaching: In Situ Destruction vs Expulsion JAMES M. CERVINO1*, RAYMOND HAYES2, THOMAS J. GOREAU3, and GARRIET W. SMITH4 1University of South Carolina, Marine Sciences Department, Columbia, SC 29208, Email. [email protected]; 2College of Medicine, Howard University, Washington, DC; 3Global Coral Reef Alliance, Cambridge, MA; 4University of South Carolina, Aiken, SC, USA Received November 3, 2003; Accepted March 1, 2004 Abstract Impairment and breakdown in the symbiotic relationship between the coral host and its zooxanthellae has been documented in the major Caribbean reef building coral, Montastraea spp., when it is infected with yellow band/blotch disease (YBD) pathogens and/or exposed to unusually high seawater temperatures. Progressive degradation of zooxanthellar cellular integrity occurs, leading to the deterioration of coral tissue. Cytoplasmic organelles were displaced and chloroplasts are reduced and marginalized which is accompanied by internal swelling, vacuolization, fragmentation, and loss of cell wall structural integrity. Changes in algae that occur in YBD-infected corals differ from changes seen in corals undergoing solely temperature-induced coral bleaching, however. In many disease-infected corals, there is no evidence of zooxanthella in the mucus, unlike in thermal bleaching, where zooxanthellae was evident in the coral surface layer. Isolated zooxanthellae Presented at the 4th International Symbiosis Congress, August 17–23, 2003, Halifax, Canada *The author to whom correspondence should be sent. 0334-5114/2004/$05.50 ©2004 Balaban 64 J.M. CERVINO ET AL. inoculated with YBD pathogens showed a 96% decrease in chlorophyll a pigments compared to controls, and a 90% decrease in mitotic cell division over 96 hours of YBD bacterial inoculation (<p=0.0016). -
Cnidarian Immunity and the Repertoire of Defense Mechanisms in Anthozoans
biology Review Cnidarian Immunity and the Repertoire of Defense Mechanisms in Anthozoans Maria Giovanna Parisi 1,* , Daniela Parrinello 1, Loredana Stabili 2 and Matteo Cammarata 1,* 1 Department of Earth and Marine Sciences, University of Palermo, 90128 Palermo, Italy; [email protected] 2 Department of Biological and Environmental Sciences and Technologies, University of Salento, 73100 Lecce, Italy; [email protected] * Correspondence: [email protected] (M.G.P.); [email protected] (M.C.) Received: 10 August 2020; Accepted: 4 September 2020; Published: 11 September 2020 Abstract: Anthozoa is the most specious class of the phylum Cnidaria that is phylogenetically basal within the Metazoa. It is an interesting group for studying the evolution of mutualisms and immunity, for despite their morphological simplicity, Anthozoans are unexpectedly immunologically complex, with large genomes and gene families similar to those of the Bilateria. Evidence indicates that the Anthozoan innate immune system is not only involved in the disruption of harmful microorganisms, but is also crucial in structuring tissue-associated microbial communities that are essential components of the cnidarian holobiont and useful to the animal’s health for several functions including metabolism, immune defense, development, and behavior. Here, we report on the current state of the art of Anthozoan immunity. Like other invertebrates, Anthozoans possess immune mechanisms based on self/non-self-recognition. Although lacking adaptive immunity, they use a diverse repertoire of immune receptor signaling pathways (PRRs) to recognize a broad array of conserved microorganism-associated molecular patterns (MAMP). The intracellular signaling cascades lead to gene transcription up to endpoints of release of molecules that kill the pathogens, defend the self by maintaining homeostasis, and modulate the wound repair process. -
What Is Coral Bleaching
Mote Marine Laboratory / Florida Keys National Marine Sanctuary Florida Keys BleachWatch Program CORAL BLEACHING FACT SHEET A single coral colony is made up of numerous individual coral polyps (see photo right). Corals depend on unicellular algae known as zooxanthellae located inside their tissue to provide them with carbohydrates and oxygen through photosynthesis. The zooxanthellae are usually golden brown in color and are found at various densities in individual species of corals. Some corals have additional pigments in their tissues which when combined with the zooxanthellae gives the normal “healthy” coloration of the coral. Stressed corals may lose or expel zooxanthellae. The Photo: MML transparent tissue remains with the underlying white skeleton Healthy Porites astreoides polyp showing giving the coral a bleached white appearance. This process is zooxanthellae. called coral bleaching. What Causes Coral Bleaching? Bleaching is a stress response that results when the coral-algae relationship Healthy Bleached breaks down. Coral bleaching can be caused by a wide range of environmental stressors such as pollution, oil spills, increased sedimentation, extremes in sea temperatures, Photo: MML extremes in salinity, low oxygen, disease, and Comparison of healthy (left) and paling (middle) and bleached (right) brain coral Colpophyllia natans. predation. The corals are still alive after bleaching and do not necessarily always die. If the environmental conditions return to normal rather quickly, the corals can regain or regrow their zooxanthellae and survive. If the stressors are prolonged, the corals are more susceptible to disease, predation, and death because they are without an important energy source. Past, Present …FUTURE? Localized or colony specific bleaching has been recorded for over 100 years but only in the last 20 years have we seen mass bleaching events. -
Life on Our Reefs a Colouring Book
LIFE ON OUR REEFS A COLOURING BOOK Ministry of Fisheries and Agriculture Maté, Republic of Maldives & For Fisheries Development BAY OF BENGAL PROGRAMME This colouring-cum-information book on coral reefs for schoolchildren evolved out of the effort of the subproject ‘Fisheries Extension Services, Maldives (MDV/FES/MDV)’. The focus of the subproject, guided by the fisherfolk, was on building awareness and beginning the consultative processes that would, in time, lead to participatory management of coral reef resources. In doing so, the subproject also reached out to schoolchildren in the islands, the future fisherfolk of the Maldives, through this book. The text, in both Divehi and English, is aimed at primary schoolchildren (6-14 years). The book is intended to be used as a colouring book as well as a reader. It is written by Mr. N.T. Hasen Didi, former Director in the Ministry of Fisheries and Agriculture (MOFA) and an eminent naturalist and artist, and Ms Sana Mohamed, ReefBiologist, Marine Research Section, MOFA. The book was illustrated by Mr. Hussein Zahir, a Biologist on study leave from the Marine Research Section of MOFA, who is also an artist and an enthusiastic diver. The fisheries extension services project, and this book, have been sponsored by the Bay of Bengal Programme’s ‘Small-Scale Fisherfolk Communities in the Bay of Bengal’ (GCP/RAS/ 118/MUL), a project jointly funded by SIDA (Swedish International Development Authority) and DANIDA (Danish International Development Agency) and executed by FAO (Food and Agriculture Organization of the United Nations). The Bay of Bengal Programme (BOBP) is a multiagency regional fisheries programme which covers seven countries around the Bay of Bengal — Bangladesh, India, Indonesia, Malaysia, Maldives, Shri Lanka and Thailand.