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Geoscientist Online

World Seas—An Environmental Evaluation: Volume III, Ecological Issues and Environmental Impacts

Sheppard World SeasThe year 2000 saw the publication of Seas at the Millennium, which reviewed the environmental condition of the oceans. Focussing on human interactions with the physical and biological aspects of marine environments, it described methods and techniques that might ensure the continued functioning of aquatic ecosystems.

This present volume is primarily a second edition Seas at the Millennium, addressing changes over the last two decades. The environmental story documented is one of continued and relentless decline in marine quality. However, techniques (such as benthic surveys using GPS and satellite photographs) have developed markedly. The topic range being wide (environments, techniques, pollutants), only selected examples more likely to be of interest to geoscientists are highlighted here.

Four chapters describe challenges faced by mangroves, coral reefs, kelp forests and salt marshes—each nurseries for economically-important species. Climate change is a major issue for each. Mangrove forests and salt marshes are being squeezed between human settlements and shifting shorelines as sea level rises. Kelp forests, whose canopies dominate the shallow sublittoral at higher latitudes, need cold winters to reproduce. They are being pushed polewards as temperatures warm.

A chapter on the transport of harmful, invasive species in ballast water suggests that these are also a great anthropogenic threat to the aquatic world. (Such species will be encountered by palaeontologists examining modern environments.) It is recommended that an early warning system be put in place to notify national authorities. Invasive species can also be introduced on floating plastic fragments now stranded on shorelines. Regarding oil spill impacts, knowledge growth has not kept pace with hydrocarbon exploration and production.

Submarine noise, as from seismic surveys, is a pervasive pollutant impacting cetaceans, fish, invertebrates and larvae. Meanwhile, collisions between ships and cetaceans are largely underestimated events that “can threaten whole populations and even species”. Chapters on micro- and macro-plastics document the effects of sedimentation and ingestion, and the impact of ghost fishing from discarded traps and nets.

Oxygen-poor Marine Dead Zones in coastal ecosystems are increasing in number and area—as in the Gulf of Mexico. These have arisen from excess inputs of nutrients and organic matter, but from climate change also. Some, such as in the Baltic Sea, are now permanent features. 

Thus, there is much here to interest geoscientists working on modern environments. It will be a pity if, this book being so expensive and dense scientifically, it is not also widely read by environmentally-concerned citizens, politicians and corporate leaders.

Reviewed by Brent Wilson

WORLD SEAS, AN ENVIRONMENTAL EVALUATION, 2nd EDITION: VOLUME III, ECOLOGICAL ISSUES AND ENVIRONMENTAL IMPACTS, by Charles Sheppard (ed), 2018, Academic Press (an imprint of Elsevier), 666 pp. ISBN-10: 0128050527, ISBN-13: 978-0128050521 (pbk.) List price: £230.00 W: