Seafloor Geomorphology as Benthic Habitat

GeoHAB Atlas of Seafloor Geomorphic Features and Benthic Habitats

Peter Harris, Elaine Baker, Peter Harris, Elaine Baker

• Publisher: Elsevier
• Year: 2011
• ISBN:
  9780123851413
• Topic: Scienze biologiche
• Subtopic: Ecologia

The conservation of marine benthic biodiversity is a recognised goal of a number of national and international programs such as the United Nations Convention on Biodiversity (CBD). In order to attain this goal, information is needed about the distribution of life in the ocean so that spatial conservation measures such as marine protected areas (MPAs) can be designed to maximise protection within boundaries of acceptable dimensions. Ideally, a map would be produced that showed the distribution of benthic biodiversity to enable the efficient design of MPAs. The dilemma is that such maps do not exist for most areas and it is not possible at present to predict the spatial distribution of all marine life using the sparse biological information currently available.

Knowledge of the geomorphology and biogeography of the seafloor has improved markedly over the past 10 years. Using multibeam sonar, the benthic ecology of submarine features such as fjords, sand banks, coral reefs, seamounts, canyons, mud volcanoes and spreading ridges has been revealed in unprecedented detail.

This book provides a synthesis of seabed geomorphology and benthic habitats based on the most recent, up-to-date information. Introductory chapters explain the drivers that underpin the need for benthic habitat maps, including threats to ocean health, the habitat mapping approach based on principles of biogeography and benthic ecology and seabed (geomorphic) classification schemes. Case studies from around the world are then presented. They represent a range of seabed features where detailed bathymetric maps have been combined with seabed video and sampling to yield an integrated picture of the benthic communities that are associated with different types of benthic habitat. The final chapter examines critical knowledge gaps and future directions for benthic habitat mapping research.

• Reviews and compares the different methodologies currently being used
• Includes global case studies
• Provides geological expertise into what has traditionally been a biological discipline

1. Why Map Benthic Habitats?

Peter T. Harris¹ and Elaine K. Baker²

¹Marine and Coastal Environment Group, Geoscience Australia, Canberra, ACT, Australia

²UNEP/GRID- Arendal School of Geosciences, University of Sydney, Australia

Habitat is the property that inherently integrates many ecosystem features, including higher and lower trophic level species, water quality, oceanographic conditions and many types of anthropogenic pressures. Thus, strengthening assessments of status and trends in habitat quality and extent will be an important priority in the development of a global marine assessment.

(Assessment of Assessments Report, UNEP and IOC-UNESCO[1])

This introductory chapter provides an overview of this book’s contents and definitions of key concepts, including benthic habitat, potential habitat, and seafloor geomorphology. It concludes with a summary of commonly used habitat mapping technologies. Benthic (seafloor) habitats are physically distinct areas of seabed that are associated with particular species, communities, or assemblages that consistently occur together. Benthic habitat maps are spatial representations of physically distinct areas of seabed that are associated with particular groups of plants and animals. Habitat maps can illustrate the nature, distribution, and extent of distinct physical environments and, importantly, they can predict the distribution of the associated species and communities.

The data sets collected for constructing habitat maps provide fundamental information that can be used for a range of management and industry applications, including the management of fisheries, spatial marine environmental management, design of marine reserves, supporting offshore oil and gas infrastructure development, port and shipping channel construction, maintenance dredging, tourism, and seabed aggregate mining. Seafloor habitat mapping provides fundamental baseline information for decision makers working in these sectors.

GeoHab (www.geohab.org) is an international association of marine scientists conducting research using a range of mapping technologies in the study of biophysical (i.e., geologic and oceanographic) indicators of benthic habitats and ecosystems as proxies for biological communities and species diversity. Using this approach, combinations of physical attributes of the seabed identify habitats that have been demonstrated to be effective surrogates for the benthic communities that they typically support. Thus, management priorities can be identified using seabed habitat maps as a guide. The work of GeoHab demonstrates how knowledge of seabed properties can be employed to guide marine environmental management, marine resource management, and conservation efforts.

Seafloor geomorphology is one of the most useful physical attributes of the seabed mapped and measured by GeoHab scientists. Different geomorphic features (e.g., submarine canyons, seamounts, atolls, and fjords) are commonly associated with particular suites of habitats. Knowledge of the geomorphology and biogeography of the seafloor has improved markedly over the past 10 years. Using multibeam sonar, submarine features such as fjords, sand banks, coral reefs, seamounts, canyons, and spreading ridges have been revealed in unprecedented detail. The 57 case studies presented in this book represent a range of seabed geomorphic features where detailed bathymetric maps have been combined with seabed video and sampling to yield an integrated picture of the benthic communities that are associated with different types of benthic habitat.

Key Words: Benthic habitats; geomorphic features; physical surrogates; biodiversity; spatial marine planning; environmental management; habitat mapping technology

General Outline of the Content of This Book

This book provides a synthesis of seabed geomorphology and benthic habitats based on up-to-date information contained in the case studies. Part 1 of the book provides an introduction in which the drivers that underpin the need for benthic habitat maps are examined, including threats to benthic habitats. The habitat mapping approach a...