Return of the Mac: how Density Affects the Survival of Juvenile Giant Kelp (Macrocystis Pyrifera) in Point Loma Kelp Forest, San Diego, CA PDF Download
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Author: Publisher: ISBN: Category : Electronic books Languages : en Pages : 34
Book Description
Adult giant kelp, Macrocystis pyrifera, release billions of zoospores into the surrounding kelp forest community during each reproductive season. The young sporophytes that ultimately develop from these zoospores undergo a process of self-thinning until their densities are reduced to levels that can be sustained by environmental conditions at that time. We examined the effects of recruitment density on the survival of juvenile M. pyrifera within naturally occurring patches in the Point Loma kelp forest, San Diego, CA and found that the total density of all macroalgae within the patch had no effect on M. pyrifera survival. Instead, we found that density-dependent mortality within each patch was driven almost entirely by the density of conspecifics. This pattern, and the direct effects of recruitment density on juvenile M. pyrifera survival was further tested experimentally by oputplanting two size classes of juvenile M. pyrifera (medium size class, 5-25cm in height; large size class, ~1m in height) at three densities (20, 60 and 120 individuals m-2, and 2, 4 and 8 individuals m-2 for medium and large size classes, respectively). While the large size class exhibited the overall greatest survival, declines in survival were consistent through time for all density treatments and for each size class, with the surviving sporophytes converging on similar densities (8 m- 2 ±4 for the medium size class, and 1 m-2 ±1 for the large size class). Together, our observational and our experimental studies demonstrate that, regardless of the initial density at which M. pyrifera recruits, the resulting patches of juvenile sporophytes will thin to similar densities that are presumably appropriate for their survival under the existing environmental conditions. This self-thinning process is an example of density-dependent mortality that operates in addition to other stressors such as grazing, sand scour, entanglement and dislodgement due to wave energy, each of which effectively reduces the population size of new M. pyrifera recruits to a level that is sustainable by the kelp forest community.
Author: Publisher: ISBN: Category : Electronic books Languages : en Pages : 34
Book Description
Adult giant kelp, Macrocystis pyrifera, release billions of zoospores into the surrounding kelp forest community during each reproductive season. The young sporophytes that ultimately develop from these zoospores undergo a process of self-thinning until their densities are reduced to levels that can be sustained by environmental conditions at that time. We examined the effects of recruitment density on the survival of juvenile M. pyrifera within naturally occurring patches in the Point Loma kelp forest, San Diego, CA and found that the total density of all macroalgae within the patch had no effect on M. pyrifera survival. Instead, we found that density-dependent mortality within each patch was driven almost entirely by the density of conspecifics. This pattern, and the direct effects of recruitment density on juvenile M. pyrifera survival was further tested experimentally by oputplanting two size classes of juvenile M. pyrifera (medium size class, 5-25cm in height; large size class, ~1m in height) at three densities (20, 60 and 120 individuals m-2, and 2, 4 and 8 individuals m-2 for medium and large size classes, respectively). While the large size class exhibited the overall greatest survival, declines in survival were consistent through time for all density treatments and for each size class, with the surviving sporophytes converging on similar densities (8 m- 2 ±4 for the medium size class, and 1 m-2 ±1 for the large size class). Together, our observational and our experimental studies demonstrate that, regardless of the initial density at which M. pyrifera recruits, the resulting patches of juvenile sporophytes will thin to similar densities that are presumably appropriate for their survival under the existing environmental conditions. This self-thinning process is an example of density-dependent mortality that operates in addition to other stressors such as grazing, sand scour, entanglement and dislodgement due to wave energy, each of which effectively reduces the population size of new M. pyrifera recruits to a level that is sustainable by the kelp forest community.
Author: Publisher: ISBN: Category : Electronic books Languages : en Pages : 33
Book Description
The forest-forming giant kelp, Macrocystis pyrifera, and the communities it supports have been decreasing across their native ranges in many parts of the world. The sudden removal of giant kelp canopies by storms enhances space and light for the colonization ofopportunistic understory macroalgae, such as Desmarestia herbacea, which can inhibit M. pyrifera recovery and alter local community composition. Understanding the mechanisms by which D. herbacea interacts with M. pyrifera can therefore provide insight into patterns of kelp forest recovery following these disturbances, and can aid in predicting future community structure. This study experimentally tested the independent and combined effects of two likely competitive mechanisms, namely shade and scour, by which D. herbacea might inhibit recovery of M. pyrifera in the Point Loma kelp forest in San Diego, CA. We conducted field experiments on SCUBA to study the individual and combined effects of shade and scour by D. herbacea on the survival of M. pyrifera microscopic life stages, and the recruitment, survival and growth of its young sporophytes. Our results show that scour (i.e. physical abrasion by D. herbacea thalli) had the strongest effect on the survival of M. pyrifera microscopic life stages and recruitment of its young sporophytes, but shade and scour were both important for survival and growth of these sporophytes as they grew larger. Canopy-removing storms are increasing in frequency and intensity, and this change could facilitate the rise of opportunistic species, like D. herbacea, which might alter community succession and recovery of kelp forests. Understanding the mechanisms by which these opportunistic species suppress kelp recovery can therefore enhance conservation efforts.
Author: Crystal Ng Publisher: ISBN: Category : Languages : en Pages :
Book Description
Giant kelp forests are some of the most productive and biodiverse ecosystems in the world, but they are vulnerable to stressors associated with global climate change. As a foundation species, giant kelp (Macrocystis pyrifera) provides habitat, food, and refuge for hundreds of species, many of which are economically important. Much of what is known about giant kelp is focused on the adult stage and the abiotic factors influencing the persistence and recovery of this species. However, under increasing environmental variability, it is critical to understand the factors impacting the survival of juvenile kelp, which has direct implications for the success of the adults. One of the largest gaps in our knowledge of giant kelp forests is the role of a diversity of grazers on the early life stages of M. pyrifera, and virtually nothing is known about the impacts of climate change on these species interactions. In this dissertation, I use both laboratory and field experiments to quantify the impacts of four grazers on two life stages of juvenile kelp under ocean acidification and hypoxia. I found that grazers are a significant source of mortality on juvenile kelp, and that an often overlooked herbivore in the literature, the brown turban snail, emerges as a dominant grazer on both microscopic and macroscopic stages. Under climate change, consumption is significantly reduced, increasing estimated kelp survival, and hypoxia drives these decreases in consumption across all four grazing species. By utilizing natural variability regimes within an upwelling season, I found through field experiments that grazing rates decreased with high monthly oxygen variance, suggesting that cumulative impacts of more extreme conditions may also impact herbivore feeding behavior. Overall, the results of this dissertation demonstrate that herbivory can play a significant role influencing the persistence of giant kelp, and that under the threat of climate change, these species interactions will be significantly weakened, which has implications for kelp forest ecosystems and the transfer of primary productivity through these diverse food webs. This dissertation provides critical information on the ecology and persistence of giant kelp forests and gives us a greater understanding of climate change impacts on marine communities.
Author: Anonymous Publisher: Hassell Street Press ISBN: 9781014041296 Category : Languages : en Pages : 432
Book Description
This work has been selected by scholars as being culturally important and is part of the knowledge base of civilization as we know it. This work is in the public domain in the United States of America, and possibly other nations. Within the United States, you may freely copy and distribute this work, as no entity (individual or corporate) has a copyright on the body of the work. Scholars believe, and we concur, that this work is important enough to be preserved, reproduced, and made generally available to the public. To ensure a quality reading experience, this work has been proofread and republished using a format that seamlessly blends the original graphical elements with text in an easy-to-read typeface. We appreciate your support of the preservation process, and thank you for being an important part of keeping this knowledge alive and relevant.
Author: James B. McClintock Publisher: CRC Press ISBN: 1420036602 Category : Science Languages : en Pages : 626
Book Description
The interdisciplinary field of marine chemical ecology is an expanding and dynamic science. It is no surprise that the breadth of marine organisms studied expanded in concert with developments in underwater technology. With its up-to-date subject reviews by experts, Marine Chemical Ecology is the most current, comprehensive book on the subject. The
Author: E.A. Drew Publisher: Elsevier ISBN: 0323150314 Category : Science Languages : en Pages : 439
Book Description
Underwater Research is primarily a review of problems in underwater viewing and hearing and acoustics. The chapters in this book are papers collated from the symposia of the Underwater Association. This book explores the need for the further study of the physiological and psychological reactions of divers. The book also concludes that diving is still the best way in studying the benthic ecology and sunken wrecks and cities. The text is divided into 25 detailed chapters. Most of the topics in the text address the common problems encountered by divers such as in hearing and viewing. Specifically, problems in diver communication, depth estimation, color distinction are some of the topics covered. Other chapters deal with the psychological reactions such as anxiety, narcosis, and visual attention. Also, some chapters tackle solutions and experiments for the improvement of diving techniques and equipment. This reference is helpful to divers, students, and scientists involved in marine and environmental science.
Author: Jorge L. Sarmiento Publisher: Princeton University Press ISBN: 0691017077 Category : Nature Languages : en Pages : 526
Book Description
Ocean Biogeochemical Dynamics provides a broad theoretical framework upon which graduate students and upper-level undergraduates can formulate an understanding of the processes that control the mean concentration and distribution of biologically utilized elements and compounds in the ocean. Though it is written as a textbook, it will also be of interest to more advanced scientists as a wide-ranging synthesis of our present understanding of ocean biogeochemical processes. The first two chapters of the book provide an introductory overview of biogeochemical and physical oceanography. The next four chapters concentrate on processes at the air-sea interface, the production of organic matter in the upper ocean, the remineralization of organic matter in the water column, and the processing of organic matter in the sediments. The focus of these chapters is on analyzing the cycles of organic carbon, oxygen, and nutrients. The next three chapters round out the authors' coverage of ocean biogeochemical cycles with discussions of silica, dissolved inorganic carbon and alkalinity, and CaCO3. The final chapter discusses applications of ocean biogeochemistry to our understanding of the role of the ocean carbon cycle in interannual to decadal variability, paleoclimatology, and the anthropogenic carbon budget. The problem sets included at the end of each chapter encourage students to ask critical questions in this exciting new field. While much of the approach is mathematical, the math is at a level that should be accessible to students with a year or two of college level mathematics and/or physics.
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Author: Crystal Ng
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Author: Jorge L. Sarmiento