Download or read book Effects of Predators on Sea Urchin Abundance and Behavior on Southern California Rocky Reefs and Caribbean Coral Reefs written by and published by . This book was released on 2018 with total page 183 pages. Available in PDF, EPUB and Kindle. Book excerpt: The interactions between predators and their prey are key drivers of structure and functioning in many ecosystems. However, the ability of predators to effectively regulate prey abundance can be strongly modified by the context in which trophic interactions occur. My dissertation explores the effects of five factors which have the potential to mediate trophic interactions on nearshore reefs: prey density, organismal body size, habitat complexity, animal behavior, and fishery harvest. Working on both temperate rocky reefs and tropical coral reefs, I use field- and lab-based experiments as well as a numerical model to better understand the interactions among sea urchins, their finfish and invertebrate predators, and the nearshore reefassociated communities of which they are a part. Chapters 1 and 2 focus on the dynamics between sea urchins, spiny lobsters, and fish predators on the rocky reefs of southern California. Following the extirpation of the archetypal urchin predator, the sea otter (Enhydra lutris), top-down control of urchins in this system by spiny lobsters (Panulirus interruptus) and the labrid fish California sheephead (Semicossyphus pulcher), has been hypothesized, but rarely tested experimentally. Chapter 1 tests for densitydependent mortality of purple (Strongylocentrotus purpuratus) and red (Mesocentrotus franciscanus) urchins due to predation by finfish and lobsters. In laboratory feeding assays, spiny lobsters demonstrate a saturating functional response to urchin prey, whereby urchin proportional mortality is inversely density-dependent. In field experiments on rocky reefs near San Diego, CA, when purple urchins are offered alone, I find evidence of positive density-dependent urchin mortality at low densities, similar to those found within kelp forests. At higher prey densities, analogous to those found within urchin barrens, prey mortality is density-independent. When red and purple urchins are deployed to reefs simultaneously, urchin mortality is density-independent and fish do not aggregate to higher density patches. This shift in predation mortality is likely due to the increased biomass of the alternative red urchin prey rather than the increased structural complexity offered by their large spine canopy. Overall, results from Chapter 1 suggest that topdown control of urchins can occur only under limited circumstances, when predatory fish are abundant and large red urchins are absent. In Chapter 2, I develop a tri-trophic, size-structured numerical model of a southern California rocky reef. The model includes multiple ecological processes that can drive feedbacks across trophic levels leading to alternative stable states, including recruitment facilitation and size-structured predation. I find that fishery harvest for the predator (spiny lobster) and prey (red urchins) interacts to determine the level of ecological resilience exhibited by the system, i.e. the likelihood of shifting between alternative stable states. Specifically, I show that predator harvest can drive the system from a kelp forest to an urchin barren, but that prey harvest determines the likelihood of this shift. Size-structured predation on urchins is the feedback maintaining a given ecosystem state. This model suggests that ecosystem resilience depends on both predator and prey harvest in multi-trophic level harvest scenarios, which are common in marine ecosystems but are rarely accounted for by traditional single-species management. Collectively, my first two chapters demonstrate that predator regulation of urchins can occur only under limited circumstances which strongly depend on both predator and prey body size and species composition. These findings also have significant implications for the dynamics of alternative community states observed on rocky reefs, as harvesting predators and harvesting prey can interact to determine the ecological resilience of these important coastal habitats. In addition to density and organismal body size, habitat complexity can also play a vital role in shaping ecological communities. However, many coral reef ecosystems are shifting to alternative states with reduced structural complexity and altered community assemblages. Smallbodied herbivores, such as sea urchins, are common inhabitants of reefs, and their importance for controlling the distribution and abundance of algae in marine ecosystems is well understood. Less understood is the role of habitat complexity and species identity of foundational species in dictating the abundance of this increasingly-important group of herbivores. In Chapters 3 and 4, I explore the feedbacks between habitat complexity, herbivorous urchins, and their predators on fringing coral reefs of Bocas del Toro, located on the Caribbean coast of Panama. In Chapter 3, I use benthic surveys, tethering, and laboratory experiments to show that the structural complexity and species identity of three corals commonly observed on Caribbean reefs mediate the abundance, behavior, and demographic characteristics of an increasingly important herbivore, the reef urchin Echinometra viridis. Tethered urchins survive better on the more structurally complex coral Agaricia tenuifolia and hydrocoral Millepora alcicornis than on less complex branching Porites species. However, natural densities of urchins on these corals do not follow the same pattern, suggesting that coral identity, independent of complexity, also contributes to habitat associations. In habitat choice experiments, urchins prefer the structurally complex coral A. tenuifolia only when waterborne cues of predators are introduced. Despite minimal differences in the standing stock of algae associated with the different corals, urchins inhabiting Porites colonies have a marginally higher reproductive condition than those collected from the other corals, suggesting a fitness trade off to inhabiting the riskier coral. Understanding the drivers of herbivore habitat associations is vital for predicting the persistence of coral-dominated reefs due to feedbacks between changing coral reef communities (both species identity and habitat complexity) and shifts to algal dominance. In Chapter 4, I explore the potential for non-consumptive effects (NCEs) of predatory spiny lobsters on the grazing and movement behaviors of two urchins (E. viridis and Diadema antillarum) which contribute to Caribbean coral reef resilience. Non-consumptive effects of predators on their prey can be an important influence on ecosystems because predators can suppress the ecological function of far more prey than they can consume. However, herbivore responses to predatory risk cues can differ among species which otherwise could be functionally similar. Cues from a generalist predator, the Caribbean spiny lobster (Panulirus argus), strongly suppress grazing by Diadema but not Echinometra. Conversely, cues produced by simulated predation on conspecific urchins cause reduced grazing by Echinometra but not Diadema. In field tests for NCEs on movement behavior, Echinometra consistently move away from lobsters on coral colonies of a variety of structural complexity levels, but movement rates are reduced in response to lobster cues only when on highly rugose corals. Diadema movement is not affected by the presence of lobsters. The contrasting responses exhibited by these two urchins suggest that herbivore populations and their functional roles may respond in unexpected ways to anthropogenic changes to predator communities and reef structural complexity. Together, these chapters provide evidence of the importance of small-bodied herbivores to Caribbean coral reef resilience through feedbacks between herbivory and habitat complexity and improve our understanding of trophic interactions on degraded contemporary coral reefs.

Download or read book Sea Urchins written by John M. Lawrence and published by Academic Press. This book was released on 2020-01-17 with total page 734 pages. Available in PDF, EPUB and Kindle. Book excerpt: Sea Urchins: Biology and Ecology, Fourth Edition, Volume 43 expands its coverage to include the entire class of Echinoidea, making this new edition an authoritative reference of the entire class of species. This is a valuable resource that will help readers gain a deep understanding of the basic characteristics of sea urchins, the basis of the great variation that exists in sea urchins, and how sea urchins are important components of marine ecosystems. Updated coverage includes sections on reproduction, metabolism, endocrinology, larval ecology, growth, digestion, carotenoids and disease. Includes pertinent tables and graphs within chapters to visually summarize information Provides case studies with research applications to provide potential solutions Includes the entire class of Echinoidea and the effect of climate change on the biology and ecology of the species

Download or read book Effects of Predators on the Behaviour and Morphology of a Habitat forming Sea Urchin written by Arie J.P. Spyksma and published by . This book was released on 2016 with total page 180 pages. Available in PDF, EPUB and Kindle. Book excerpt: Predators have well documented density-mediated effects on sea urchin populations, which can indirectly influence sea urchin resources (predominantly macroalgae) via a trophic cascade. Less is known about how predators may affect sea urchin behaviour and morphology and the ecological implications of these interactions. Predators may directly affect sea urchin behaviour and morphology through trait-mediated interactions, or they may indirectly affect these characteristics via cascading trophic effects that increase sea urchin food availability, resulting in behaviours or morphologies similar to those expressed in direct response to predators. Using a range of field and laboratory experiments I aimed to determine the direct and indirect effects of predators on the behaviour and morphology of the habitatforming sea urchin Evechinus chloroticus. In two well-established north-eastern New Zealand marine reserves, where large snapper (Pagrus auratus) and rock lobster (Jasus edwardsii) have suppressed grazing by E. chloroticus with a resultant increase in kelp densities, E. chloroticus remained cryptic in crevices to significantly larger sizes than individuals on the adjacent overfished reefs. Crevice occupancy in sea urchins has previously been attributed to either predator avoidance or a response to plentiful food in the form of kelp detritus. E. chloroticus in the marine reserves had much greater access to kelp and other macroalgae than those in the barrens habitat on fished reefs, meaning predators could be responsible for cryptic behaviour via direct (predator avoidance) and/or indirect (trophic cascade) mechanisms. A mesocosm experiment, using adult sea urchins, found that the addition of predation cues (injured conspecifics) strongly increased cryptic behaviour, but food availability had no effect. Sea urchins within marine reserves were found to have thicker, more crush-resistant tests than those on the adjacent overfished reefs. This putative structural defence could be directly induced by predation cues, or indirectly induced in response to the greater food supply arising from the cascading effect that predation on sea urchins has on kelp abundance. In a six month-long mesocosm experiment, well-fed juvenile sea urchins developed less porous, more crush-resistant tests than those that were poorly fed. Predation cues alone had a relatively minor effect on crush-resistance. A number of field experiments were carried out to further examine the behavioural response of sea urchins to predation cues from injured conspecifics. Exposed E. chloroticus fled from cues released by injured conspecifics, but not those from an extraneous pilchard cue, alarm cues from an injured heterospecific, or the disturbance caused by fish attracted to the cues, indicating that E. chloroticus can distinguish between different cues. The response to injured conspecific cues was limited to within one meter of the cue. Exposed sea urchins avoided reentering an area containing cues throughout the night while in areas where sea urchins were predominantly cryptic an injured conspecific above the crevices restricted the number of sea urchins leaving during the night in order to find food on the reef. On barren reefs sea urchins densities recovered within several days following a 'predation event'. Overall, the results show that predators directly affect the behaviour of E. chloroticus by causing them to flee or increasing their use of crevices and indirectly affect their morphology by increasing their supply of food. Predator induced changes in behaviour and morphology are likely to enable sea urchin populations to persist in areas where predation pressure is high. Where sea urchins are able to shelter from their predators, predation cues are also likely to play an important role in facilitating behaviourally-mediated trophic cascades or maintaining areas of existing kelp forest.

Download or read book The Effects of Predators and Habitat on Sea Urchin Density and Behavior in Southern California Kelp Forests written by Kathryn D. Nichols and published by . This book was released on 2009 with total page 68 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Gulf and Caribbean Research written by and published by . This book was released on 2005 with total page 516 pages. Available in PDF, EPUB and Kindle. Book excerpt:

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 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.

Download or read book Biology and Ecology of Shallow Coastal Waters written by Anastasios Eleftheriou and published by Olsen & Olsen. This book was released on 1995 with total page 408 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Habitat Associations and Shelter Use Behaviors in the California Spiny Lobster written by and published by . This book was released on 2014 with total page 52 pages. Available in PDF, EPUB and Kindle. Book excerpt: Predation is an important process that has both direct and indirect effects on species and communities. Many prey species utilize refuge habitat and exhibit gregarious behavior to reduce the risk of predation, and these strategies may be particularly advantageous to early life stages that are highly susceptible to predators. In this study, I worked with the California spiny lobster (Panulirus interruptus Randall) to explore patterns in habitat utilization and sheltering behavior on southern California rocky reefs, and to determine how these associations and behaviors influence survival of subadult (5.0 - 6.0 cm carapace length, CL) lobsters. The California spiny lobster is a gregarious, shelter-dwelling species whose distribution, abundance, and survival may be closely tied to habitat structure at a variety of scales, particularly for subadult lobsters that are vulnerable to a variety of predators. It is also an economically and ecologically valuable species that is among those targeted for protection in California's recently established South Coast Region marine protected areas (MPAs). Many ecological processes are tied to species-habitat interactions, and MPAs may have little impact on populations if appropriate and complex habitat is lacking within an MPA. Therefore, an important component of my study was to provide baseline information on spiny lobster behavior and habitat associations that may be used in future efforts to determine whether MPAs are positively affecting P. interruptus populations, and if behavioral shifts occur due to changing conditions within MPAs. In part one of my study, I assessed habitat characteristics and lobster behavior (habitat associations and shelter use) within and outside of four of the South Coast Region MPAs within southern California's heavily fished coastal waters. To link lobster presence and behavior to benthic habitat features at the regional level, and to determine if these linkages vary among locations, I conducted SCUBA-based transect surveys of rocky reefs within and outside of each MPA. I recorded substrate composition, relief, and dominant vegetation cover to characterize habitat, as well as the number, size, and shelter type utilized by all lobsters encountered. I found that substrate composition and algal assemblage varied across the region and that each MPA had distinct habitat characteristics. As a result, the odds of finding lobsters were related to different habitat variables within each MPA, and no single benthic feature reliably predicted the occurrence of lobsters across the entire study region. Lobster density varied only slightly across MPAs, and lobsters were generally gregarious across the study region. However, lobster sheltering behavior varied among MPAs, which may be due to variation in habitat parameters and biotic factors (e.g., predation risk and intraspecific interactions) across the southern California region.

Download or read book Spatial Behavior Marine Reserves and the Northern California Red Sea Urchin Fishery written by Martin Daniel Smith and published by . This book was released on 2001 with total page 494 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Benefits of Marine Protected Areas written by Australian Government - Department of the Environment and Heritage - Environment Australia and published by . This book was released on 2003 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Metabolic Ecology written by Richard M. Sibly and published by John Wiley & Sons. This book was released on 2012-04-30 with total page 394 pages. Available in PDF, EPUB and Kindle. Book excerpt: Metabolic Ecology Most of ecology is about metabolism, the ways that organisms use energy and materials. The energy requirements of individuals (their metabolic rates) vary predictably with their body size and temperature. Ecological interactions are exchanges of energy and materials between organisms and their environments. Therefore, metabolic rate affects ecological processes at all levels: individuals, populations, communities and ecosystems. Each chapter focuses on a different process, level of organization, or kind of organism. It lays a conceptual foundation and presents empirical examples. Together, the chapters provide an integrated framework that holds the promise for a unified theory of ecology. The book is intended to be accessible to upper-level undergraduates and graduate students, but also of interest to senior scientists. Its easy-to-read chapters and clear illustrations can be used in lecture and seminar courses. This is an authoritative treatment that will inspire future generations to study metabolic ecology.

Download or read book Reefs and Related Carbonates written by Stanley H. Frost and published by . This book was released on 1977 with total page 448 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Ecology of Fjords and Coastal Waters written by Hein Rune Skjoldal and published by Elsevier Publishing Company. This book was released on 1995 with total page 650 pages. Available in PDF, EPUB and Kindle. Book excerpt: The International Symposium on the Ecology of Fjords and Coastal Waters held in December 1994, was divided into various sessions which included: physical processes and seasonal patterns; fronts, advection and distributional patterns; harmful algae; and fish ecology and stock interactions.

Download or read book Sea Urchin Abundance Patterns in Seagrass Meadows written by Brian D. Keller and published by . This book was released on 1976 with total page 78 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Large Scale Influences of Fishing Fish and Habitat on Sea Urchin Abundance on Fijian Coral Reefs written by Rebecca Elizabeth Mitchell and published by . This book was released on 2004 with total page 173 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Sea Urchin Ecology written by Benjamin P. Weitzman and published by . This book was released on 2020 with total page 248 pages. Available in PDF, EPUB and Kindle. Book excerpt: Ecosystem structure and function of temperate rocky reef habitats are subject to change as a result of food-web modification, climate change, and changes in biological community interactions. Sea urchins are a global driver of change in nearshore marine habitats though their ability to heavily graze marine vegetation and force rocky reef ecosystems from kelp forest to sea urchin barren ground states. The Aleutian Archipelago in southwest Alaska provided an ideal natural laboratory to study sea urchin (Strongylocentrotus spp.) ecology following the functional loss of the keystone predator, the sea otter (Enhydra lutris) during the 1990s. The objectives of this dissertation were to 1) determine the important drivers of sea urchin demographics following the functional loss of their keystone predator; 2) determine how projected ocean warming and acidification may affect sea urchin physical condition; and 3) identify biological drivers of sea urchin recruitment in both kelp forest and barren ground habitats. To determine demographic drivers, I used a time series of benthic habitat, sea urchin demographic, and environmental data, dating back almost forty years. In the absence of sea otters, environmental conditions, specifically ocean temperatures, became more important to sea urchin demographics, but recruitment was the primary process affecting the resultant abundance and size class structure over time. To understand how predicted ocean warming and acidification could impact S. polyacanthus survival, growth, calcification, gonad development, and energy content, a 108-day laboratory experiment was conducted. This experiment determined that temperature caused a greater reduction in survival than acidification, and that projected changes in temperature and acidification will result in investment trade-offs between reproduction and maintenance or growth of somatic and calcified tissues. To determine how recruitment varied between kelp forest and sea urchin habitats, fine-scale surveys of benthic community structure found that specific taxa, and not overall community structure, correlated with sea urchin recruitment. Results from this dissertation will allow managers to make predictions about how sea urchin demography will change as a result of keystone predator loss and climate change and how that will affect nearshore community structure and function. Overall, my dissertation establishes likely pathways by which coastal habitats may change over time, in a system no longer under strong top-down control.