Red abalone and sea urchins are both important herbivores that potentially compete with each other for resources like food and space along the California coast. Red abalone supported a socioeconomically important recreational fishery during this study (which was closed in 2018) and red sea urchins support an important commercial fishery. Both red sea urchins and red abalone feed on the same macroalgae (including Pterygophora californica, Laminaria setchellii, Stephanocystis osmundacea, Costaria costata, Alaria marginata, Nereocystis leutkeana), and a low abundance of this food source during the period of this project may have created a highly competitive environment for urchins and abalone. Evidence that suggests competition between red abalone and red sea urchins can be seen within data collected during the years of this study (2014-2016): a significantly higher red sea urchin density, concomitant with a significantly lower red abalone density, was observed within areas closed to commercial sea urchin harvest (in MPAs) compared to nearby reference areas open to sea urchin harvest. In addition, a significant negative relationship was found between red abalone and red sea urchin abundances when examined at the 60 m2 transect level: transects with higher abundances of red sea urchins contained fewer red abalone. Designating MPAs that are closed to sea urchin harvest, in the absence of sea urchin predators such as sunflower stars (Pycnopodia helianthoides), sea otters (Enhydra lutris), spiny lobster (Panulirus interruptus), and predatory fish species, (such as the sheephead (Semicossyphus pulcher) found in Southern California), may all have contributed to an increase in red sea urchin abundances and a concomitant decrease in red abalone within the Cabrillo MPA studied in this project.

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.

Sea otters and polar bears are carnivorous marine mammals that still resemble their terrestrial ancestors. Compared with Cetacea (whales and dolphins), Sirenia (dugongs and manatees), and Pinnipedia (seals, sea lions, and walrus), they are less adapted for an aquatic life and the most recently evolved among marine mammals. Sea otters are amphibious but seldom come ashore, and polar bears primarily occur on sea ice or along the shore. When at sea, both species spend most of their time swimming at the surface or making short, shallow dives when foraging or pursuing prey. Indeed, polar bears rarely pursue seals in water. Nevertheless, polar bears are powerful swimmers and will stalk seals from the water. As with many other large carnivores, they are solitary hunters. Although sea otters are gregarious and form aggregations at sea called rafts, they are primarily asocial. Except during mating, the principal interaction among sea otters occurs between a female and offspring during the six-month dependency period. In large carnivores (e.g., wolves and lions) that feed on ungulates, sociality and cooperation are favored because of the need to capture large prey and defend carcasses. Polar bears, which are the largest terrestrial carnivore, are solitary hunters of seals and are neither gregarious nor social. Males and females briefly associate during courtship and mating. During this time, males aggressively compete for females. At other times, males generally avoid each other except for aggregations of males that form while summering on land, and females with cubs avoid males, which are known for infanticide. As with sea otters, the interaction of polar bears outside of mating occurs between a female and her offspring during the 2-3 year dependency period. This interaction is critically important when altricial cubs are born in the winter den. This book provides new insight into the ethology and behavioral ecology of sea otters and polar bears. Each chapter reviews the discoveries of previous studies and integrates recent research using new techniques and technology. The authors also address historic and current anthropogenic challenges for their survival as climate change alters entire marine ecosystems.

Sea otters are good indicators of ocean health. In addition, they are a keystone species, offering a stabilizing effect on ecosystem, controlling sea urchin populations that would otherwise inflict damage to kelp forest ecosystems. The kelp forest ecosystem is crucial for marine organisms and contains coastal erosion. With the concerns about the imperiled status of sea otter populations in California, Aleutian Archipelago and coastal areas of Russia and Japan, the last several years have shown growth of interest culturally and politically in the status and preservation of sea otter populations. Sea Otter Conservation brings together the vast knowledge of well-respected leaders in the field, offering insight into the more than 100 years of conservation and research that have resulted in recovery from near extinction. This publication assesses the issues influencing prospects for continued conservation and recovery of the sea otter populations and provides insight into how to handle future global changes. - Covers scientific, cultural, economic and political components of sea otter conservation - Provides guidance on how to manage threats to the sea otter populations in the face of future global changes - Highlights the effects that interactions of coastal animals have with the marine ecosystem

Ecologists have long struggled to predict features of ecological systems, such as the numbers and diversity of organisms. The wide range of body sizes in ecological communities, from tiny microbes to large animals and plants, is emerging as the key to prediction. Based on the relationship between body size and features such as biological rates, the physics of water and the amount of habitat available, we may be able to understand patterns of abundance and diversity, biogeography, interactions in food webs and the impact of fishing, adding up to a potential 'periodic table' for ecology. Remarkable progress on the unravelling, describing and modelling of aquatic food webs, revealing the fundamental role of body size, makes a book emphasising marine and freshwater ecosystems particularly apt. In this 2007 book, the importance of body size is examined at a range of scales that will be of interest to professional ecologists, from students to senior researchers.

The impetus for this volume comes from two sources. The first is scientific: by virtue of a preference for certain large benthic invertebrates as food, sea otters have interesting and significant effects on the structure and dynamics of nearshore communities in the North Pacific. The second is political: be cause of the precarious status of the sea otter population in coastal California, the U.S. Fish and Wildlife Service (USFWS) announced, in June 1984, a proposal to establish a new population of sea otters at San Nicolas Island, off southern California. The proposal is based on the premise that risks of catastrophic losses of sea otters, due to large oil spills, are greatly reduced by distributing the population among two geographically separate locations. The federal laws of the U.S. require that USFWS publish an Environmental Impact Statement (ElS) regarding the proposed translocation of sea otters to San Nicolas Island. The EIS is intended to be an assessment of likely bio logical, social, and economic effects of the proposal. In final form, the EIS has an important role in the decision of federal management authority (in this case, the Secretary of the Interior of the U.S.) to accept or reject the proposal.