FWS/OBS-82/32 October 1983 lOlC C:c·,;.s,~ :,~c«,;<fa•.rcwd Sfafo(i, Li\ 70458 THE ECOLOGY OF TIDAL MARSHES OF THE PACIFIC NORTHWEST COAST: A COMMUNITY PROFILE by Denise M. Seliskar John L. Gallagher College of Marine Studies University of Delaware Lewes, DL 19958 Project Officers Wiley M. Kitchens, John Cooper, and Penny Herring National Coastal Ecosystems Team U.S. Fish and Wildlife Service 1010 Gause Boulevard Slidell, LA 70458 Perfonned for National Coastal Ecosystems Team Division of Biological Services Fish and Wildlife Service U.S. Department of the Interior Washington, DC 20240 Library of Congress Number: LC 83-600580 This report should be cited as follows: Sel iskar, O. M., and J. L. Gallagher. 1983. The ecology of tidal marshes of the Pacific ft>rthwest coast: a community profile. U.S. Fish and Wildlife Service, Division of Biological Services, Washington, D.C. FWS/OBS-82/32. 65 pp. PREFACE This tidal marsh community profile is chemical environment in which the organ­ part of a series of publications concern­ isms live. The third chapter treats the ing coastal habitats. The purpose of this biotic communities of tidal marshes. In profile is to describe the structure and the Pacific l'brthwest, there has histori­ ecological functions of tidal marshes of cally been more emphasis placed on struc­ the Pacific l'brthwest coast. This habitat tural aspects of the pl ant community than is ciassified by Cowardin et al. (1979) as on the functional roles for two reasons. occurring in the estuarine system, inter­ First, the diversity and zonation in the tidal subsystem, emergent v1etland class, Oregon and Washington Marshes are so and persistent subclass with a regularly striking that even ecologists oriented to­ or irregularly flooded water regime. The ward mineral cycling and energy fl ow can­ water chemistry is mixohal ine and the not help but think of indices of similar­ soils are mineral or organic. ity, line-point transects, and cluster analyses. Second, and perhaps coincident­ This profile is a synthesis of scien­ ally, most of the botanists workin'g in the tific infonnation and 1 iterature available coastal zone happen to be interested in on various aspects of tidal marsh ecology. cominuni ty structure. There has been much research on some topics and in these areas we will discuss The fourth chapter of the profile representative data. Little infonnation focuses on ecological interactions within specifically collected in the geographic tidal marshes and between marshes and reg ion is available on other topics. In adjacent systems. There is a paucity of the latter cases we have 1 ooked to other this type of infonnation from the wetlands regions where conditions are similar and of Oregon and Washington. Most of the have suggested probable conclusions when research on these topics in the region is future research on that topic is conducted from Canada and describes work relating to in the Pacific l'brthwest. salmon in British Columbia. Much of the local infonnation for this section was The coastal marshes of the region dot drawn from our experiences in the marshes the rocky coast. As seen on the cover of of Oregon and our discussions with others this publication, narrow inlets from the working there. Many of the ideas are sea open to protected bays where ma rs hes speculative in nature, and we have care­ fonn the ecotone between upland and the fully tried to point out when the data are estuarine habitat. Marsh plants probe the inadequate to make definitive statements. emerging mudflats for a suitable physical and chemical envi ronr.ient. On the upland Chapter 5 is a discuss ion of 11anage­ fringe, where soil aeration increases and r:ient practices. It examines both the his­ salinity drops, these pl ants lose their torical approach and future management competitive advantage to the upland plants. efforts built on the current understanding This profile is focused on these estuarine of the role of these discontinuous wet­ ecotones. lands in the coastal zone of the Pacific l'brthwest. The final chapter sur.inari zes The first two chapters of the text the major points about the Pacific l'brth­ discuss the development of Pacific l'brth­ west tidal marshes and compares them to west coastal wetlands and the physical and those at other sites. i i i -- The authority used for plant names all other cases. in this profile is Hitchcock and Conquist ( 19 73}. The authority used for bi rd names Any questions, comments about, or is American OrAithologists 1 Union (AOU requests for this publication should be 1982). addressed to: The metric sys tern is used throughout this report except in those cases where Infonnation Transfer Specialist the convention of the field is to use Eng- National Coastal Ecosystems Team 1 ish units (i.e., soil horizons in inches, U.S. Fish and Wildlife Service fish weights in pounds). For ease in com­ W\SA-Sl idel l Computer Complex parison, English equivalents are given for 1010 Gause Boulevard tenperature, area, and tidal heights. A Slidell, Louisiana 70458 table of conversion values is provided for iv CONTENTS PREFACE • • • • iii FIGURES •••• vi TABLES • • • • vii ACKNOWLEDGMENTS • • • • viii CONVERSION FACTOR TABLE ix CHAPTER 1 PHYSICAL AND CHEMICAL ENVIRO!f.1ENT •••• 1 1.1 Regional Climate and Meteorology •• 1 1. 2 Tidal Regimes and Water Relations •••• 2 1. 2.1 The Estuaries ••••••••• 3 1. 2. 2 River Systems and Runoff ••• 4 1.2.3 Tidal Creeks ••••••••• 6 1. 3 Soils - Salinity and Fertility • • ••• 6 CHAPTER 2 MARSH DISTRIBUTION • • • • •• 10 2.1 Distribution of Tidal Marshes 10 2.2 Types of Ma rs hes • • • • • • • 11 CHAPTER 3 BIOTIC COMMUNITIES ••••••••••••••• 15 3.1 Vegetation - Zonation and Species Distribution • 15 3.2 Microbes • • • • • 22 3.3 Faunal Components 25 3.3.1 Invertebrates 25 3.3.2 Fi shes • 30 3.3.3 Birds 32 3.3.4 Mammals • 34 CHAPTER 4 ECOLOGICAL INTERACTIONS •••••• 37 4.1 Ecological Processes Within the Marsh 37 4.1.1 Primary Production • • • • • • • ••• 37 4.1.2 Decomposition • • • • • • • • • ••• 41 4.1. 3 Grazing • • ••• 42 4.1.4 Food Webs • • • • 42 4.1. 5 Uses of the Marsh • • • • • • 43 4.2 Mineral Cycling in the Marsh •••••.•••••.• 47 4.3 Interactions Between the Marsh and Adjacent Ecosystems • 48 CHAPTER 5 MANll.GEMENT • • • • • • • • • • • • • • . • • • • • 50 5.1 Sensitivity to Natural and Cultural Perturbations 50 5.2 His tori ca 1 Management Approach • • • • • • . • • • 51 5.3 Upland Marsh Boundaries ••.•••••• 54 5.4 Current Management Practices and Future Prospects 56 CHAPTER 6 SUMMARY AND COMPARISONS 58 REFERENCES 60 v FIGURES Number 1 An annual precipitation pattern for coastal Oregon at Tillamook in 19 79 • . • • • . • . • . • . • • . • • . 2 2 Typical daily tidal curve for Astoria, Oregon ••••.•••• 3 3 High tides at Netarts Bay, Oregon •••.••.•.•••••••• 4 4 Stream patterns in the marsh at the head of Netarts Bay, Oregon 6 5 Marsh soil moisture tension during the growing season at Netarts Bay, Oregon, at a depth of 10 cm • • • • . • • • • • • • • • • 9 6 Location of estuaries in Oregon and Washington •••••••••••• 11 7 Zone of accretion at the marsh-mudflat interface •••••.• 12 8 Pickleweed as a pioneer on the tidal flat in a low sandy marsh 20 9 Seaside plantain growing in a low sandy marsh ••••••••• 20 10 Circular clumps of arrow-grass in a low silty marsh •••••• 21 11 Lyngbye' s sedge marsh in a brackish estuary •••••••••• 21 12 Pacific sil verweed fran a mature high marsh •••••••••• 22 13 Typical zonation of marsh plants in a saline Pacific Northwest ti da 1 rna rs h • • • • • • • • • • • • • • . • • • • • • • • • • 23 14 Possible zonation pattern in a brackish Pacific Northwest t1dal marsh .•.••.........•..•..•....• 23 15 Examples of the range of variations in vegetational zonation in Pacific tbrthwest tidal marshes •••••••••••••••••••• 24 16 Drift line in an Oregon low sandy marsh ••••••••••••• 26 17 Conceptual model of carbon flow between components ·of tidal marsh ecosystems in the Pacific Northwest •••••••••••••••• 38 18 Conceptual model of energy or material fl ow between tidal marshes and other coastal ecosystems in the Pacific Northwest •••••• 49 19 Lyngbye's sedge marsh invading a mudflat created by a log blocking a marsh creek • . • • . • • . • • . • . • . • . • . 51 20 Diked and undiked marshlands which are being used for pasture ••• 52 21 Transition from wetland to upland ••••••••••••••••• 55 vi TABLES Number 1 Classification of estuaries of the Pacific Northwest, drainage basin area, and mean annual discharge rates • • • • • • • • • • • . • • 5 2 Description of a typical Sulfihemist (Histosol) and a typical Sulfaquent ( Enti sol) from coastal marshes • • • • • • • • • • • • • • • 8 3 Areal extent of salt marshes associated with Oregon estuaries • . 11 4 Characteristics of the eight types of marshes described for Oregon by Akins and Jefferson (1973) . • • . • . • . • . • . • . • . 13 5 Eight Oregon marsh community types and their typical plant species composition . 16 6 Common plant species found in Pacific Northwest tidal marshes • • . 17 7 Invertebrates characteristic of five Oregon marsh habitats. • • . • 27 8 Approximate densities and percentages of invertebrate taxa from five habitats of an Oregon marsh . • • • • • • • • • • • • • 29 9 Common and scientific names, marsh habitat, and life stage of some fishes associated with marshes of the Pacific Northwest • • • 31 10 Bird observations in salt marshes at Coos Bay . • • • • • • • • • • • • 33 11 Common and scientific names and relative abundance of birds associated with marshes of Coos Bay • • • • • • • • • • • • • • • • • • 35 12 Common and scientific names of some mammal species associated with the marshes of the Pacific Northwest •.••.••.••••••• ~ • 36 13 Representative processes of carbon flow in salt marsh communities • • • 39 14 Primary production estimates of selected Oregon marsh pl ants 41 15 Relative importance of prey items of the dominant fishes of Woodward Island marsh channels • • • • • • • • • • . • • • • 45 16 Landfills on lands lying between the line of ordinary high water and the line of ordinary low water in selected Oregon estuaries • • 53 vii ACKNOWLEDGMENTS We are indebted to all those who have­ printed by Pam Palinski and Lewis Nelson.