The Biology and Ecology of Giant Kelp Forests

The Biology and Ecology of Giant Kelp Forests

David R. Schiel
Michael S. Foster
Copyright Date: 2015
Edition: 1
Pages: 416
https://www.jstor.org/stable/10.1525/j.ctt14btfvw
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  • Book Info
    The Biology and Ecology of Giant Kelp Forests
    Book Description:

    The largest seaweed, giant kelp (Macrocystis) is the fastest growing and most prolific of all plants found on earth. Growing from the seafloor and extending along the ocean surface in lush canopies, giant kelp provides an extensive vertical habitat in a largely two-dimensional seascape. It is the foundation for one of the most species-rich, productive, and widely distributed ecological communities in the world.Schiel and Foster's scholarly review and synthesis take the reader from Darwin's early observations to contemporary research, providing a historical perspective for the modern understanding of giant kelp evolution, biogeography, biology, and physiology.The authors furnish a comprehensive discussion of kelp species and forest ecology worldwide, with considerations of human uses and abuses, management and conservation, and the current and likely future impacts of global change.This volume promises to be the definitive treatise and reference on giant kelp and its forests for many years, and it will appeal to marine scientists and others who want a better appreciation and understanding of these wondrous forests of the sea.

    eISBN: 978-0-520-96109-8
    Subjects: Ecology & Evolutionary Biology, Aquatic Sciences, Environmental Science

Table of Contents

  1. Front Matter
    (pp. i-vi)
  2. Table of Contents
    (pp. vii-x)
  3. PREFACE
    (pp. xi-xii)
  4. ACKNOWLEDGMENTS
    (pp. xiii-xiv)
  5. INTRODUCTION
    (pp. xv-xvi)

    Giant kelp (Macrocystis) forests support some of the most species-rich communities on earth. With plants reported up to 60 m long growing from the seafloor and extending along the sea surface in lush canopies, these forests are true “biogenic engineers” that provide extensive vertical habitat in a largely two-dimensional seascape, alter the light environment, and dampen water motion. Well before Darwin (1839) published the first observations on their ecology, these forests provided food and other resources for human populations. Even with only limited observations from the sea surface and collections, Darwin was clearly fascinated by giant kelp and the diverse...

  6. PART I. THE BIOLOGY OF GIANT KELP
    • 1 INTRODUCTION TO GIANT KELP FORESTS WORLDWIDE
      (pp. 3-22)

      Macrocystis, commonly called giant kelp but also known as giant bladder kelp, string kelp (Australia), huiro (Chile), and sargasso gigante (Mexico), is a genus of brown algae, a group characterized by containing the accessory photosynthetic pigment fucoxanthin that gives them their characteristic color. Historically, brown algae were classified as plants in the Domain Eukaryota, Kingdom Plantae, and Phylum (Division) Phaeophyta. The Plantae contained most terrestrial plants and also included two other common algal phyla with multicellular species, the green (Chlorophyta) and red algae (Rhodophyta). Collectively, the large marine species in these three phyla are commonly called “seaweeds.” It is now...

    • 2 THE STRUCTURE, FUNCTION, AND ABIOTIC REQUIREMENTS OF GIANT KELP
      (pp. 23-40)

      Macrocystismay be unique among large, community-dominating plants because it is essentially a “weed.” Within a wide range of environmental conditions and if spores and suitable rocky substrata are available,Macrocystiscan quickly colonize surfaces, grow rapidly, and become reproductive in less than a year. It does not require facilitation by other species and, with some local exceptions, its population dynamics are largely driven by changes in the oceanographic environment. Its biological attributes are therefore particularly relevant to its ecology. To understand howMacrocystisfunctions within the environment, it is necessary to consider not only its life history traits but...

    • 3 THE ABIOTIC ENVIRONMENT
      (pp. 41-70)

      The nonbiological environment defines the “fundamental niche” space occupied by giant kelp. This includes the physical and chemical conditions that allowMacrocystissettlement, growth, reproduction, primary production, and biomass accumulation. These include the abiotic requirements for growth and reproduction as well as suitable substratum characteristics and water motion regimes, and their temporal and spatial variability. Of course, these factors rarely act separately, are often correlated with each other, and interact with one or more life stages of kelp. All species, however, occur within a climate envelope of multiple physical conditions that affect their growth, reproduction, recruitment, and survival. For marine...

    • 4 DEMOGRAPHY, DISPERSAL, AND CONNECTIVITY OF POPULATIONS
      (pp. 71-98)

      The presence, absence, status, and connectivity of kelp forests are essentially a numbers game based on demographic characteristics of settlement, growth, mortality, and reproduction. Unsurprisingly, the demography of giant kelp is as variable as its morphology, responses to the abiotic environment, and interactions with other members of its community. Because giant kelp lives mostly in dynamic nearshore waters, occupying much of the water column, its susceptibility to partial or complete removal from severe water motion is a driving force in its ability to persist and replenish populations. Density-dependent and density-vague processes come into play as canopies and plants are thinned...

  7. PART II. THE GIANT KELP ECOSYSTEM
    • 5 GIANT KELP COMMUNITIES
      (pp. 101-140)

      Areas with giant kelp include a multitude of other species. Because giant kelp is usually dominant, however, is the most visually obvious species, and commonly has by far the greatest biomass, such areas are called giant kelp communities. They are also called giant kelp “forests” or kelp “beds.” Between these terms we prefer “forests” to “beds” because it highlights the vertical structure in the water column and the surface canopy. The abundance of giant kelp varies considerably across areas, and adults may become temporarily absent for many reasons, such as the population being annual, or being removed by grazers, storms,...

    • 6 DETACHED GIANT KELP COMMUNITIES, PRODUCTION, AND FOOD / CONTROL WEBS
      (pp. 141-162)

      Kelp populations are exceptionally productive and an estimated 80% of the productivity (excluding dissolved organic carbon) ends up as detached detritus (review in Krumhansl and Scheibling 2012). Giant kelp is no exception, and it is therefore not surprising that detritus fromMacrocystis, moved by currents and wind, can be an important source of habitat, food, and nutrients for other communities and components within kelp forests. Large size and distribution throughout the water column make fronds and entireMacrocystisplants especially vulnerable to detachment from waves and surge, and grazing concentrated in and above the holdfast results in further losses (e.g.,...

    • 7 FACILITATIVE AND COMPETITIVE INTERACTIONS IN GIANT KELP FORESTS
      (pp. 163-176)

      Of the myriad interactions that occur in giant kelp forests, most emphasis has been on processes that remove kelp through trophic relationships. Relatively few studies have explored the ways in which nonconsumptive interactions affect overall forest composition and the array of patches encountered within a kelp forest. These interactions can be facilitative or competitive. To many, these direct and indirect interactions are made possible by higher-order trophic dynamics, such as reduced grazing by sea urchins because top predators such as sea otters are present. To others, these interactions are key relationships involving fundamental processes of settlement, recruitment dynamics, light adaptations...

    • 8 GRAZING IN KELP COMMUNITIES
      (pp. 177-196)

      The major agent of loss of kelp other than water motion and natural senescence of fronds is grazing. A rich and diverse array of species make their living feeding on kelp and kelp-derived detritus within most kelp forests, both directly and indirectly through the food web and trophic interactions. As illustrated in previous chapters, these interactions occur across many feeding types and up to five trophic levels. These include primary producers (kelp and other algae), primary consumers (the herbivores), secondary consumers (smaller mobile predators), and tertiary consumers (or secondary predators; figure 5.11), with some authors delineating a higher level of...

    • 9 PREDATION AND TROPHIC CASCADES IN KELP COMMUNITIES
      (pp. 197-214)

      The overwhelming focus of predation and trophic cascades in kelp communities has been the relationships between sea urchins and their predators. From the earliest days of observations of the formation of barren ground habitats, it was conjectured that the reduction of predators through hunting and overfishing played a key role in the expansion of sea urchin populations (North and Pearse 1970, Breen and Mann 1976, Estes et al. 1978). There are arguments both for and against the pervasive role of predators and their controlling influence on sea urchin populations, and the literature has somewhat of a split personality on this...

  8. PART III. HUMAN USAGE, MANAGEMENT, AND CONSERVATION
    • 10 ANTHROPOGENIC EFFECTS ON KELP FORESTS
      (pp. 217-234)

      Because giant kelp forests occur near the shore, they are immediately subjected to runoff and waste discharge from land. They can also be affected by shoreline modifications that result in loss of rocky habitat, increased turbidity, and changes in sediment distribution. Boat traffic and anchoring can thin canopies and remove entire plants, and be vectors for introducing non-native species. Shipping and oil extraction accidents can bathe the forest in petroleum products. Harvesting for food and chemicals removesMacrocystisand associated organisms. Of course, forests are also embedded in the larger ocean which is changing as a result of human activities....

    • 11 HUMAN USAGE OF GIANT KELP AND KELP FOREST ORGANISMS
      (pp. 235-264)

      Giant kelp and its associated species have supported many human uses and activities, from food and chemicals to recreation and cultural enrichment. As discussed in Chapter 1, the impetus for a better understanding of the biology and ecology of giant kelp beginning in the early 1900s was the development of harvesting and processing facilities in California for the production of potash and, later, alginate. AlthoughMacrocystisis now only a minor species in the extraction industry, its other uses are varied and some are important for human activities. In this chapter, we discuss the uses of giant kelp as well...

    • 12 MARINE PROTECTED AREAS AND FISHERIES EFFECTS
      (pp. 265-282)

      There are many conservation, ethical, and societal reasons to implement marine protected areas (MPAs) (e.g., Airame et al. 2003), but MPAs and overfi shing seem linked like the Gemini twins, with perhaps fishing in the role of Castor (the mortal who perished before being revived) and MPAs in the role of Pollux (the immortal who came to the rescue); if they are not actually bound together, they are at least within each other’s gravitational pull. Although there are many human activities that have impacts on marine areas (e.g., Sousa 2001, Schiel 2009, for reviews), fishing is the chief means of...

  9. PART IV. HUMAN USAGE, MANAGEMENT, AND CONSERVATION
    • 13 GLOBAL CHANGE
      (pp. 285-302)

      The preponderance of evidence is that the earth’s climate is changing at an unprecedented rate, and many predictions are dire about the consequent changes on ecosystems. In regard to the ocean, the major physical variables of change are likely to be temperature, wave forces, sea level, and pH from increasing atmospheric CO₂ (Brierley and Kingsford 2009, IPCC 2013). Climate change must be viewed, however, within the context of numerous other stressors from increasing human populations, urbanization, intensified land use, coastal runoff of sediments, nutrients, and contaminants, species extractions, and the spread of nonindigenous species (e.g., Schiel 2009, Smale et al....

    • 14 GIANT KELP FORESTS: CONCLUSIONS AND FINAL THOUGHTS
      (pp. 303-316)

      Giant kelp forests have achieved an iconic status among the world’s marine ecosystems and within the scientific literature. With ever-increasing numbers of nature tourists, scuba divers, recreational fishers, and wide-reaching nature documentaries, both the natural beauty of giant kelp forests and the key role they play in the provision of “services” are much better appreciated globally. Within the scientific literature, giant kelp forests have been a focal point for discussions about regime shifts and alternate states of coastal ecosystems, and they have fed into a growing nexus of ecological theory and management models related to spatial planning (e.g., Foley et...

  10. AFTERWORD
    (pp. 317-318)

    Writing this book has been a pleasant and at times arduous journey through the scientific literature, which has revealed far more depth and quality of science than we were aware of before we began. We enjoyed rereading the discoveries of early kelp forest pioneers, from natural historians and taxonomists to the first diving scientists. We realized that our own careers collectively span the period from these firsthand observers (MSF was a student of M. Neushul) through generations of students and research scientists to the present. But most of all, we could time travel to the past to two young students,...

  11. REFERENCES
    (pp. 319-382)
  12. INDEX
    (pp. 383-395)