Transcript Chapter 8
Chapter 8 Temperate Coastal Seas More than 90% of marine animals are benthic, living in close association with the seafloor, at the interface with the overlying water, dependent on the characteristics of each and the exchange of substances between the two. Copyright © 2004 Jones and Bartlett Publishers Chapter 8 Seafloor Characteristics •The composition of the sea bottom is determined by • plankton, wastes, and detritus • the activities of organisms that live there • the energy in waves and currents in shallow water Chapter 8 Seafloor Characteristics •Fig. 8.1 In coves and bays, refraction of advancing ocean waves spreads out the wave crests and concentrates them on headlands and other projecting coastal features. Chapter 8 Seafloor Characteristics •Fig. 8.4 Sandstone erosion pits created by the rasping actions of small chitons. Chapter 8 Animal–Sediment Relationships •Benthic animals are either – epifaunal, living on the sediment, or – infaunal, living within the sediment. Chapter 8 Animal–Sediment Relationships •Suspension filter feeders obtain their food from passing waters Fig. 8.5 Barnacles, Balanus, attached to a small snail shell, with their feathering filtering appendages extended. (Courtesy of T. Phillipp) Chapter 8 Animal–Sediment Relationships •Fig. 8.6 A sea star, Pisaster, feeding on a mussel. Chapter 8 Larval Dispersal •75% of slow-moving, sedentary, or attached animals extend their geographic range by broadcast spawning of eggs and sperm that will result in larvae that are temporarily planktonic (or meroplanktonic). Chapter 8 Larval Dispersal •Fig. 8.9 Typical duration of planktonic existence for four common groups of marine benthic invertebrates. Adapted from Thorson 1961. Chapter 8 Larval Dispersal •Bottom type, bottom texture, chemical attractants, current speeds, sounds, light, and presence of conspecific adults influence meroplanktonic larvae to settle on the seafloor and metamorphose into a juvenile form. Chapter 8 Larval Dispersal •Fig. 8.10 Several major environmental factors that influence the selection of suitable bottom types by planktonic larvae. Chapter 8 Intertidal Communities •Daily fluctuations in tidal heights result in an intertidal, or littoral, zone forming on all shorelines, regardless of slope or texture. •This zone is inhabited by species of marine origin that experience physiological stress during periods of low tide. Chapter 8 Intertidal Communities •Rocky Shores – Distance from low water is correlated with variations in physical and biological stresses, resulting in distinct horizontal bands of zonation. Chapter 8 Intertidal Communities •Rocky Shores Fig. 8.13 Exposure curves for the Pacific coast of the United States and the Atlantic coast of England. Adapted from Ricketts and Calvin 1968, and Lewis 1964. Chapter 8 Intertidal Communities •Rocky Shores – The upper intertidal of rocky shorelines hosts organisms that suffer with frequent desiccation and punctuated food supplies. Fig. 8.19 Stunted acorn barnacles, Chthamalus, survive in the shallow depression of carved letters. Chapter 8 Intertidal Communities •Rocky Shores – The middle intertidal is more densely populated with species more troubled by competition for food and space than physical limitations of the environment. Fig. 8.23 Close-up view of mussels, Mytilus, and acorn barnacles, Balanus, in the middle intertidal. Chapter 8 Intertidal Communities •Rocky Shores – The lower intertidal hosts a much more diversified assemblage of plants and animals that are exposed to air for only a short period of time each day. Fig. 8.26 Sea stars, Pisaster, aggregating near the low tide line to avoid desiccation. Chapter 8 Intertidal Communities •Sandy Beaches – Sandy beaches and muddy shores are depositional environments characterized by deposits of unconsolidated sediments and accumulations of detritus. Chapter 8 Intertidal Communities •Sandy Beaches Fig. 8.33 Sandy beach zonation along the East Coast of the United States. Chapter 8 Intertidal Communities •Oiled Beaches – Because oil is less dense than seawater, when it is spilled (intentionally or not), most of it ends up in intertidal zones. Chapter 8 Intertidal Communities •Oiled Beaches Fig. 8.40 A heavily oiled beach in Prince William sound after the Exxon Valdez oil spill. (Courtesy of J. Harvey) Chapter 8 Shallow Subtidal Communities •Below the effects of waves and tides, kelp communities dominate in temperate areas. Fig. 8.45 General structure of a West Coast kelp forest, with a complex understory of plants beneath the dominant Macrocystis or Nereocystis.