Download or read book Spatial Dynamics of Crustose Coralline Algae and Turf Algae as an Indicator of Reef Recovery written by Christina Jayne and published by . This book was released on 2018 with total page 53 pages. Available in PDF, EPUB and Kindle. Book excerpt: In 2015, prolonged warming caused severe bleaching across reefs in the Main Hawaiian Islands resulting in widespread coral mortality. In addition to understanding changes in coral populations, it is also important to study algal dynamics on these reefs, especially with a focus on crustose coralline algae (CCA) and turf algae. CCA can serve as indicator for coral growth and recovery, thus playing a significant role in determining the future of bleached coral reefs. Meanwhile, turf algae quickly occupies available space, competes with corals and prevents coral settlement. To assess the state of these Hawaiian reefs, a large-scale mosaic imaging technique has been in use since 2014 to document the conditions of select sites before and after the bleaching event. These 33 m2 photomosaics cover three reefs in leeward Maui across a gradient of herbivore biomass and sediment input. Analysis of the mosaics shows marked differences in turf and CCA spatial dynamics and percent cover between sites. Sites more protected from anthropogenic influences had the greatest CCA growth, while the site most impacted by local stressors lost CCA abundance and had the highest increase in turf algae. This suggests local management and stressors around a reef may affect CCA and turf growth, and therefore influence coral recovery. The large-area mosaic imaging method may serve as a useful model for analyses of reef resilience on coral reefs.
Download or read book Spatial and Temporal Ecology of Corals and Algae on Palmyra Atoll Central Pacific Following Thermal Disturbance written by Adi Khen and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Coral reefs are valuable ecosystems that provide billions of dollars globally in ecological goods and services, but they are facing widespread degradation due to climate change. This dissertation provides insights into the dynamics of coral bleaching and recovery, responses of other key taxa such as algae, and broader ecological implications for coral reef communities in the context of thermal stress. Chapter 1 of the dissertation synthesizes results from past studies on coral bleaching: while bleaching severity was highly variable as expected, this was complicated by inconsistent response metrics and the fact that bleaching measurements are often taken at different timing with respect to the onset of thermal stress. By standardizing existing observations, this chapter allows for inter-study comparison of coral bleaching susceptibility by genus, morphology, and/or region. Chapter 2 uses a time series of underwater imagery taken yearly for the past decade from two habitats on Palmyra Atoll to quantify the cover of reef-building corals, crustose coralline algae, macroalgae, turf, and other invertebrates. One year after each of the thermal anomalies in 2009 and 2015, some sites experienced reductions in coral cover which were replaced by turf or crustose coralline algae. However, across the entire decade, benthic community structure changed minimally at the functional group level, with greater stability at the reef terrace as compared to the fore reef. Chapter 3 of the dissertation tracks the growth, discoloration (i.e., lack of pigmentation), partial or whole-colony mortality, survival, and/or regrowth of individual coral colonies on Palmyra. This chapter explores which species were more sensitive or tolerant than others when exposed to thermal stress, and whether a colony's level of discoloration at the time of warming corresponds to its fate one year later. Finally, Chapter 4 evaluates the long-term effects of increased seawater temperatures on benthic algae. This chapter investigates the abundance of fleshy and calcareous algae on Palmyra's reef habitats over time, and suggests that a major macroalgal genus, Halimeda spp., showed evidence of temperature sensitivity. Long-term monitoring data sets from Palmyra can be used to establish baseline information for the conservation and restoration of more-threatened reefs at risk of decline.
Download or read book Environmental and Biotic Controls Affecting Recruitment and Proliferation of Algal Turf Communities in Coral Reef Systems written by Camille Jazmin Gaynus and published by . This book was released on 2019 with total page 108 pages. Available in PDF, EPUB and Kindle. Book excerpt: Worldwide, coral reef communities are collapsing and shifting from coral to algal dominance. While human activities changing top-down (overfishing of grazers) and bottom-up (increases in nutrients and sediments) forces can initiate shifts, complex, non-linear interactions among stressors limit predictability (Hughes et al., 2007;Bellwood et al., 2004). Further, while top-down control is known to limit algal dominance (Knowlton & Jackson 2008; Jackson et al., 2001), less is known about bottom-up controls that may facilitate algae. One functional group of algae is turf algae, which are multi-species and often filamentous, ranging from 0.01-10cm in height (Fong & Paul 2011). Short, closely-cropped turf algae provide ecosystem functions such as primary productivity, trophic support, and nutrient cycling (Fong & Paul 2011). Under environmental stress, however, turf algae can shift to long sediment-laden turf, which may be an alternative stable state that inhibits coral recovery (Adjeroud et al., 2009). My first objective was to compare variation in the assembly of turf algae under a suite of top-down and bottom-up contexts at six sites on fringing reefs in Mo'orea French Polynesia. At each site, 10 settlement tiles were deployed and monitored for two-months and then after twelve months. During the first two months I also measured herbivore abundance, grazing pressure, sediment composition, nutrient availability, benthic community structure, and sediment deposition rates at each site. After two months turf did not vary among plots, despite significantly different herbivore abundances and nutrient availability. This implies that early successional forms are easily controlled, even by low numbers of herbivores, due to their high palatability. In contrast, after one year, tiles in highly grazed sites with low sedimentation rates were dominated by crustose coralline algae, and sites with low herbivores and high sedimentation rates dominated by long turf and macroalgae. As crustose coralline algae can facilitate coral recruitment, these results imply that herbivory can mediate the successional trajectory of algal communities toward recovery by coral or stability of the shifted algal state. A robust herbivorous fish community is the paradigm of a healthy coral reef, however, altered sediment regimes can negatively influence their grazing patterns (Tebbett et al., 2018;Bellwood & Fulton 2008), leading to algal proliferation. While increases in sediment can lead to algal proliferation through reduced grazing and release from nutrient limitation, too much sediment can lead to negative turf responses (Tebbett et al., 2018) due to the buildup of anoxic-inducing bacteria (Clausing et al., 2014). Turf are particularly prone to the influence, both positive and negative, of sediment fluxes due to their filamentous nature that trap deposited sediment (Rogers 1990). The second objective of my dissertation was to establish the non-linear relationship between sediment and turf at two sites that varied in environmental context. Before manipulations commenced I conducted field surveys of sediment depth and turf height at seven fringing reef sites around Mo'orea. I found that sediment depth and turf height varied widely among sites and although longer turf did hold more sediment that shorter turf communities, it was not disproportionally more than expected. I then choose two sites that varied the greatest in turf and sediment and deployed tiles where I manipulated sediment depth (0,1,3, & 5mm) for 25 days. Because all tiles were open to herbivory, I quantified herbivorous fish communities through visual surveys. Interestingly, I found that sediment additions have overall negative impacts on turf, and that turf between sites did have different thresholds for sediment. As turf becomes a more conspicuous component of reefs worldwide, susceptible to increases in terrestrial fluxes, understanding the dynamics of this relationship will become crucial for predicting reef recovery and resilience. In the Pacific, a healthy coral reef is characterized by intact herbivorous fish communities that reduce shifts to algal dominance through grazing (Hughes et al., 2007;Mumby et al., 2006). Sea urchins are an alternate grazing guild that are less studied, especially in the Pacific, but were found to maintain healthy algal communities on Caribbean reefs (Mumby et al., 2007;Lewis et al., 1987;Carpenter 1986; Carpenter 1985). My third objective was a novel exploration of the role urchins play in limiting algal proliferation in the South Pacific, and how this may be mediated by sediment, as sediment is known to deter fish grazing. Sediment (no addition, 3mm marine, or 3 mm terrestrial/marine mix) and presence of urchins (+/-) were manipulated in plots containing turf algae on a relatively overfished reef when compared to other Mo'orean fringing reefs (data from Mo'orea Long Term Ecological Research Project). I found urchins maintained closely cropped turf even under high sediment conditions. Further, urchins removed added sediment, likely promoting consumption by fishes. Thus, urchins can be functionally redundant grazers as they can compensate for the loss of herbivorous fishes. Overall, turf is a dynamic community, sensitive to small environmental shifts dictating abundance, proliferation, and taxonomy, potentially altering its function in coral reefs.
Download or read book Coralline Algae Globally Distributed Ecosystem Engineers written by Laurie Carol Hofmann and published by Frontiers Media SA. This book was released on 2020-07-08 with total page 159 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Competition Between Coral and Algal Holobionts written by and published by . This book was released on 2012 with total page 200 pages. Available in PDF, EPUB and Kindle. Book excerpt: Coral reefs around the world have suffered devastating losses of reef building corals with a concomitant increase in benthic algae. While it is clear that a variety of local and global disturbances play a role in the replacement of corals by algae, the mechanisms behind this transition are not. Space is limited on coral reefs, and competition between corals and benthic algae plays a major role in shaping the composition of the benthos. The objective of this dissertation was to investigate the dynamics of coral-algae competition, with a focus on how different algae affect coral physiology and their associated microbes, and how these small-scale dynamics influence the distribution of corals and algae on pristine to degraded coral reefs. I found significant differences in the composition and outcomes of coral-algae interactions across reefs; corals were consistently better competitors against crustose coralline algae (CCA), but were damaged by turf algae on inhabited but not uninhabited reefs, suggesting that competition dynamics are affected by human activity. Physiological investigations of coral interactions with four common types of benthic algae (CCA, calcareous macroalgae, fleshy macroalgae, and turf algae) demonstrated that all algae except CCA cause net heterotrophy and disruption of coral tissue and pigments along the interaction border. These effects were negated by antibiotics, indicating that disruption of coral health during algal competition is mediated by microbes. These same algae were found to harbor highly diverse bacterial and eukaryotic microbial communities, but their competitive interfaces with corals hosted a community of microbes distinct from either side. Turf algae borders had a large proportion of potential pathogens, while fleshy macroalgae led to an increase of bacterial carbohydrate utilization metabolisms. This suggests that turf and fleshy macroalgae compete with corals by stimulating bacterial growth and respiration and promoting the invasion of opportunistic pathogens on corals, leading to coral mortality and freeing space for the alga. This dynamic appears to be amplified by human disturbances such as overfishing and eutrophication, which remove the top-down and bottom-up controls on algae.
Download or read book Edible Sea Urchins Biology and Ecology written by John M. Lawrence and published by Elsevier. This book was released on 2001-05-21 with total page 429 pages. Available in PDF, EPUB and Kindle. Book excerpt: Sea urchins are a major component of marine environments found throughout the world's oceans. A major model for research in developmental biology, they are also of major economic importance in many regions and interest in their management and aquaculture has increased greatly in recent years. This book provides a synthesis of biological and ecological characteristics of sea urchins that are of basic scientific interest and also essential for effective fisheries management and aquaculture. General chapters consider characteristics of sea urchins as a whole. In addition, specific chapters are devoted to the ecology of 17 species that are of major commercial interest and ecological importance. Features include: • A synthesis of what is known about the basic biological characteristics of the sea urchin, useful for the direction of future research. • Case histories of 17 species that illustrate their ecological role in a variety of environments. • With the catastrophic decline in fisheries resulting primarily from over-fishing, it is essential that the populations be managed effectively and that aquaculture be developed. This book provides knowledge of the biology and ecology of the commercially important sea urchins that will contribute to these goals. • The only book available in present literature devoted to sea urchins. With this new title experts provide a broad synthetic treatment and in depth analysis of the biology and ecology of sea urchins from around the world, designed to provide an understanding of the group and the basis for fisheries management and aquaculture.
Download or read book The Ecology of Turf Algae on Coral Reefs written by Jill L. Harris and published by . This book was released on 2015 with total page 200 pages. Available in PDF, EPUB and Kindle. Book excerpt: Coral reefs are one of the most diverse and productive ecosystems on the planet. Globally, corals are declining and algae are increasing due to anthropogenic activities. While most research and conservation efforts focus on the proliferation of macroalgae, in fact most algae on coral reefs are turf algae: heterogeneous assemblages of many species of small algae. These ubiquitous and abundant algal "shag carpets" are typically overlooked or studied as a homogenous functional group. I examine characteristics that make turf algae functionally unique from other types of algae, focusing on their ecological importance as food for reef organisms, major sources of productivity, and competitors with reef-building corals. Further, I argue that turfs will become more abundant in the future because they respond positively to the many anthropogenic threats facing coral reefs, including overfishing, pollution, acidification and warming. First, I explore the spatial patterns in turf assemblages, showing that, although turfs appear visually homogenous to the naked eye, they are highly variable at the centimeter scale. This descriptive work provides a foundation for testing ecological processes that may be causing those small-scale patterns. Second, I use turf algae as a tool to demonstrate that the relative influences of top-down and bottom-up processes are context-dependent. I measured the greatest response to grazer exclusion where background herbivory was lowest, suggesting a positive feedback between the loss of herbivory and loss of resilience. Further, in contrast to high profile findings in other ecosystems, my data revealed that nutrient enrichment increased, and consumers reduced, turf diversity. Finally, I expand the traditional perspective of coral reef herbivores to include small infaunal invertebrates living in turf algae. By partitioning herbivory among fish and small invertebrates, I provide some of the first evidence that infaunal invertebrates significantly impact turf algae, but their role depends on either competition with or predation by fish. Overall, my dissertation provides a new perspective on turf algae and opportunities to test classic ecological concepts. Additionally, a better understanding of the ecology of turf algae has urgent conservation applications, including insight into how reefs of the future will function and how to best protect them.
Download or read book Oxygen Optode Analysis of Coral algal Interactions written by and published by . This book was released on 2013 with total page 62 pages. Available in PDF, EPUB and Kindle. Book excerpt: Coral reefs contain a diverse consortium of benthic macro-organisms including scleractinian corals, fleshy algae, calcifying algae, and their associated microbiotas. These organisms are in a constant battle, competing for space and resources. Over the last 50 years, fleshy algae have increasingly been shown to outcompete corals; however, the mechanisms are not completely known. Algal-derived dissolved organic matter (DOM) can induce mortality of reef building corals. One proposed killing mechanism is a zone of hypoxia created by rapidly growing microbes. To investigate this hypothesis, oxygen optodes were used to investigate dissolved oxygen concentrations at coral-algal interfaces, as well as how the biological oxygen demand (BOD) of coral-associated microbial communities are affected by algal DOM. Oxygen optodes were visualized with a novel, low-cost Submersible Oxygen Optode Recorder (SOOpR) system, which is capable of accurately measuring oxygen concentrations in the lab or in situ. The BOD studies examined the effects of two types of algal organic matter; turf algae, shown to be detrimental to corals, and crustose coralline algae (CCA), which have been shown to be beneficial. This investigation of oxygen dynamics of coral-algal interactions shows that algae can create complex oxygen dynamics that change with flow, and when in close contact with coral, the interface becomes hypoxic. When microbial communities from coral are exposed to turf algal exudate and CCA exudate, exudates from turf algae elicit the greatest BOD. Together, the results of these studies show that coral-algal interaction zones can be hypoxic, and this is due in some part to microbial activity.
Download or read book Monitoring functional groups of herbivorous reef fishes as indicators of coral reef resilience a practical guide for coral reef managers in the Asia Pacific region written by Alison L. Green and published by IUCN. This book was released on 2009 with total page 72 pages. Available in PDF, EPUB and Kindle. Book excerpt: "This document provides practical advice to field practitioners based on an example from the Asia Pacific Region. Key functional groups of herbivores are identified, species are assigned to each functional group, and methods are provided for monitoring their abundance, biomass and size structure ... This document represents the first attempt to develop a monitoring program that is specifically designed to monitor key functional groups of herbivorous reef fishes as indicators of coral reef resilience. Even though it is based on the best available information, it is important to remember that the science underpinning these methods is still new and developing. Further research is now required to address knowledge gaps and refine monitoring methods"--Executive summary.
Download or read book Coral Reefs of the Western Pacific Ocean in a Changing Anthropocene written by Jing Zhang and published by Springer Nature. This book was released on 2022-09-08 with total page 204 pages. Available in PDF, EPUB and Kindle. Book excerpt: The monograph is based on the research and training activities in the Western Pacific Ocean Region within the umbrella of UNESCO/IOC-Sub-Commission for the Western Pacific Region. The results of these activities are compared to cases from other tropical and subtropical regions on this planet to make the knowledge applicable to global aspects of sustainability of coral reef ecosystems. In this monograph, we examine the coral reefs from viewpoint of multidisciplinary approaches, including, environmental impacts, coral biology and system ecology, biogeochemical cycles and processes that drive the material and energy flow through the food web, as well as the proxies in geochemistry that have been used to track the responses of coral reefs to the changing climate and human perturbations. Although this study is focused on the Western Pacific Ocean, the Western Pacific Ocean is so large and diverse that most reef environment types on this planet are located within it. Therefore, knowledge gained in this study is relevant to the application of coastal management in practice as well as in the teaching classes on the interactions between coral reef ecosystems with changing environments.
Download or read book The Combined Effects of Ocean Acidification with Fleshy Macroalgae and Filamentous Turfs on Tropical Crustose Coralline Algae written by Lansing Yun Perng and published by . This book was released on 2019 with total page 111 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Coral Reef Remote Sensing written by James A. Goodman and published by Springer Science & Business Media. This book was released on 2013-04-18 with total page 446 pages. Available in PDF, EPUB and Kindle. Book excerpt: Remote sensing stands as the defining technology in our ability to monitor coral reefs, as well as their biophysical properties and associated processes, at regional to global scales. With overwhelming evidence that much of Earth’s reefs are in decline, our need for large-scale, repeatable assessments of reefs has never been so great. Fortunately, the last two decades have seen a rapid expansion in the ability for remote sensing to map and monitor the coral reef ecosystem, its overlying water column, and surrounding environment. Remote sensing is now a fundamental tool for the mapping, monitoring and management of coral reef ecosystems. Remote sensing offers repeatable, quantitative assessments of habitat and environmental characteristics over spatially extensive areas. As the multi-disciplinary field of coral reef remote sensing continues to mature, results demonstrate that the techniques and capabilities continue to improve. New developments allow reef assessments and mapping to be performed with higher accuracy, across greater spatial areas, and with greater temporal frequency. The increased level of information that remote sensing now makes available also allows more complex scientific questions to be addressed. As defined for this book, remote sensing includes the vast array of geospatial data collected from land, water, ship, airborne and satellite platforms. The book is organized by technology, including: visible and infrared sensing using photographic, multispectral and hyperspectral instruments; active sensing using light detection and ranging (LiDAR); acoustic sensing using ship, autonomous underwater vehicle (AUV) and in-water platforms; and thermal and radar instruments. Emphasis and Audience This book serves multiple roles. It offers an overview of the current state-of-the-art technologies for reef mapping, provides detailed technical information for coral reef remote sensing specialists, imparts insight on the scientific questions that can be tackled using this technology, and also includes a foundation for those new to reef remote sensing. The individual sections of the book include introductory overviews of four main types of remotely sensed data used to study coral reefs, followed by specific examples demonstrating practical applications of the different technologies being discussed. Guidelines for selecting the most appropriate sensor for particular applications are provided, including an overview of how to utilize remote sensing data as an effective tool in science and management. The text is richly illustrated with examples of each sensing technology applied to a range of scientific, monitoring and management questions in reefs around the world. As such, the book is broadly accessible to a general audience, as well as students, managers, remote sensing specialists and anyone else working with coral reef ecosystems.
Download or read book Coral Recovery on Phase shifted Reefs Depend Upon the Type of Macroalgae Present written by Justin N. Voss and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The Florida Keys experienced some of the most drastic transitions from coral to macroalgae dominated states, known as phase-or regime-shifts, of any reefs in the Caribbean. Macroalgae on coral reefs lower coral recruitment by deterring coral settlement either directly through competition or indirectly by changing the chemical environment near the benthos. With evidence of species-specific interactions to coral-macroalgae competition, the type of macroalgae on a phase-shifted coral reef might be more important than just identifying a reef transition. To answer this question, I tested the effect of Laurencia intricata (a macroalgae related to the settlement inducing crustose coralline algae) and Dictyotaceae (known for its toxic or allelopathic compounds) on Porites astreoides planulae behavior, settlement and choice settlement preference, and post-settlement survival. I found that P. astreoides planulae show a positive response to chemical cues released from L. intricata, crustose coralline algae, and species in the Dictyotaceae family. However, the positive chemical cue response becomes algal-specific as larvae start probing for settlement substrate. Providing P. astreoides larvae with a choice between settlement substrates, revealed that the algal structure caused higher settlement next to L. intricata, while Dictyotaceae deterred larval settlement. It may be beneficial for larvae to settle next to L. intricata over Dictyotaceae algae. I identified that post-settlement survival was enhanced when P. astreoides larvae settled next to L. intricata while Dictyotaceae species did not enhance or deter post-settlement survival. These results indicate that coral larvae may be responding differently to a variety of chemical cues. Any chemical or physical cue from a reef may be used by coral larvae to identify and locate settlement substrate on a reef. Once they identify a reefs location, they express a more selective behavior during settlement by avoiding Dictyotaceae macroalgae and favoring L. intricata. This suggests that the composition of a phase-shifted reef matters to coral recovery, not only that it has shifted to a dominated macroalgal state.
Download or read book Oceanography and Marine Biology written by R. N. Gibson and published by CRC Press. This book was released on 2008-06-05 with total page 432 pages. Available in PDF, EPUB and Kindle. Book excerpt: Increasing interest in marine biology and its relevance to environmental issues creates a demand for authoritative reviews of recent research. Oceanography and Marine Biology has addressed this demand for nearly 40 years. This annual review considers basics of marine research, special topics, and emerging new areas. Regarding the marine sciences as a unified field, the text features contributors who are actively engaged in biological, chemical, geological, and physical aspects of marine science. This edition includes a full color insert and covers such topics as the ecological status of the Great Barrier Reef, the effects of coral bleaching on fisheries, and the biology of octopus larvae.
Download or read book Coral Reefs of the Eastern Tropical Pacific written by Peter W. Glynn and published by Springer. This book was released on 2016-08-12 with total page 666 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book documents and examines the state of health of coral reefs in the eastern tropical Pacific region. It touches on the occurrence of coral reefs in the waters of surrounding countries, and it explores their biogeography, biodiversity and condition relative to the El Niño southern oscillation and human impacts. Additionally contained within is a field that presents information on many of the species presented in the preceding chapters.
Download or read book The Telegraph Messenger s New Year s Greeting written by and published by . This book was released on 1889 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Ocean Acidification written by National Research Council and published by National Academies Press. This book was released on 2010-09-14 with total page 200 pages. Available in PDF, EPUB and Kindle. Book excerpt: The ocean has absorbed a significant portion of all human-made carbon dioxide emissions. This benefits human society by moderating the rate of climate change, but also causes unprecedented changes to ocean chemistry. Carbon dioxide taken up by the ocean decreases the pH of the water and leads to a suite of chemical changes collectively known as ocean acidification. The long term consequences of ocean acidification are not known, but are expected to result in changes to many ecosystems and the services they provide to society. Ocean Acidification: A National Strategy to Meet the Challenges of a Changing Ocean reviews the current state of knowledge, explores gaps in understanding, and identifies several key findings. Like climate change, ocean acidification is a growing global problem that will intensify with continued CO2 emissions and has the potential to change marine ecosystems and affect benefits to society. The federal government has taken positive initial steps by developing a national ocean acidification program, but more information is needed to fully understand and address the threat that ocean acidification may pose to marine ecosystems and the services they provide. In addition, a global observation network of chemical and biological sensors is needed to monitor changes in ocean conditions attributable to acidification.
