The ecology of eelgrass meadows in the Pacific Northwest: A ...

More documents

Recommendations

Info

pink shrimp, and bottom fish (Proctor et al. 1980b). Very little work has focused on or even listed infauna. The three best studies are those of Kikuchi (1966) in Japan, Thayer et al. (1975b) in North Carolina, and Orth (1973) in the Chesapeake Bay. Extensive work has been done in the Pacific Northwest by Dr. Carl Nyblade in the North Puget Sound area, but this is largely unpublished in the scientific literature and not so widely known. Figure 14. Dungeness crab (Cancer mgister) in eelgrass bed in Puget Sound. populations of soft-shell clams and crabs. In another newspaper article, Lane (1980) stated that Dungeness crabs support a sport and commercial crab fishery in Padilla Bay. Numerous species of worms, clams, snails, crabs, shrimp, and other invertebrates were identified in Padilla Bay (NOAA 1980). The density of epibenthic harpacticoid copepods, a favorite food of juvenile chum salmon in the Pacific Northwest, was four times as high in a thick stand of eelgrass than nearby in a sand habitat without eelgrass (Simenstad et al. 198W). Dense schools of juvenile chum salmon were feeding upn and among the eelgrass blades. In Grays Harbor, Washington, Dungeness crabs produce commercially important catches which range from 11,364 to 10D,000 kg (25,080-220,000 lb) (Army Corps of Engineers 1977b). Grays Harbor functions as a coastal estuary for coastal Dungeness crabs. The estuary has extensive eelgrass meadows. Bayer (1979b) studied the densities and seasonalities of Dungeness, hermit, kelp (Figure 15), and red rock crabs, and two species of crangonid shrimps in the eelgrass meadows of the Yaquina estuary, Oregon. Hwnboldt Bay is another estuary with very large sport and commercial fisheries for Dungeness crabs, Orth (1973) found 117 macroinvertebrate taxa associated with eelgrass beds in the Chesapeake Bay. Strictly speaking, not all these were infaunal, because he mentions seasonality of the fauna as many forms moved from the sediments and onto the leaves from March to July. He found that the recorded density of infauna was higher from eelgrass than from any other benthic habitat in the Chesapeake Bay system. This was also found by Kikuchi (1980) in Japan. In North Carolina, Thayer e t al. (1975b) found that the infauna was composed of 40 species and dominated by five species. Peleqpxls represented 58% and polychaetes 41% of the total individuals. The infauna was dominated by deposit feeders (53% and 44% of the abundance and biomass, respectively), while suspension feeders represented 42% and 35k, respectively. They noted a much lower density of organisms and biomass as compared to the Chesapeake Bay, and concluded it was due to the relatively recent establishment of the eelgrass bed of their study. In one study done off Skiff Point, Binbridge Island, Washington, Thorn et al. (1979) reported that the eelgrass habitat contained more invertebrates at the +1.0 m (3.0 ft) level, than at the unvegetated sites. For crustacean species there were few individuals, but a great number of species; in mollusks and annelids, species richness was intermediate or above the curves for other groups at the +1.0-m level. They theorized that the substratestabilizing effect of eelgrass may be important in causing the increased
lPable 1%. List of invertebrates found in eelgrass madows of the Pacific North-st, arranged in functional categories. Phylun, Class, and speckas scientific mme Sra fir Ootrlch plm hyf.ztc5 -- &a pl1m -" Plrnre l~ydroid P l w hydroid " - Omtrtp-stripd jelly1 ah PW\TYHEMlMTIV3 nbrlnl lar ia Z~*-M$&. sf). HiMmrl wrm -- Horn sr*l i l &kWilc ahell -- -- Wl~b-chlnk n-51 1 Cli~nnola
Page 2 and 3: ~~~/0~-84/24 September 1984 THE ECO
Page 4 and 5: PREFACE Nearly half the population
Page 6 and 7: CONTENTS PREFACE ..................
Page 8 and 9: FIGURES Number 1 2 ................
Page 10 and 11: ACKNOWLEDGMENTS I wish to acknowled
Page 12 and 13: Because eelgrass is a rooted plant,
Page 14 and 15: CHAPTER 1 THE PHYSIOGRAPHIC SETTING
Page 16 and 17: Table 1. Precipitation, temperature
Page 18 and 19: Table 2. Distribution and extent of
Page 20 and 21: Table 2. (Concluded) Extent of mat
Page 22 and 23: CHAPTER 2 THE BIOLOGY OF EELGRASS 2
Page 24 and 25: Table 4. Field observations on eelg
Page 26 and 27: leaves overtopped them and created
Page 28 and 29: 1.0- influence the redox potential
Page 30 and 31: Oxygen There are Little data to ind
Page 32 and 33: enough, increased erosion of bottom
Page 34 and 35: The terms used to describe biomass
Page 36 and 37: estimates are reported on work done
Page 38 and 39: Figure 10. Eelgrass at Blakely Isla
Page 40 and 41: increase in p~), and the sediments
Page 42 and 43: particulate matter and DOM were hig
Page 44 and 45: Table 9. Nutrient content of eelgra
Page 46 and 47: ecause it is dominated by a single
Page 48 and 49: epibenthos, and other components al
Page 50 and 51: shorebirds). From a recent thorough
Page 54 and 55: Table 13 a. (Continued) Phyltnn, cl
Page 56 and 57: Phylum, class, and Resident or Livi
Page 58 and 59: Table 13b. (concluded) Resident or
Page 60 and 61: Table 13c. (Concluded) Living Feedi
Page 62 and 63: eelgrass) , while 29 species were f
Page 64 and 65: (239,d9~,9(ii9 kg) (outram and Huln
Page 66 and 67: Washington State Game Dept., pers.
Page 68 and 69: Table 15. Energy in various ccmpart
Page 70 and 71: Export of whole by waterfowl Figure
Page 72 and 73: storms erode and dislodge some eelg
Page 74 and 75: CHAPTER 6 HUMAN IMPACTS-MANAGEMENT
Page 76 and 77: apparent darnazje. IUllzomes and ro
Page 78 and 79: great annual range of water tempera
Page 80 and 81: 1978, for all assumptions, formulat
Page 82 and 83: Table 16. ( CDncluded) Spec ies yea
Page 84 and 85: REFERENCES Rdarns, S.M. 197va. The
Page 86 and 87: seagrass community. Pages 153-162 i
Page 88 and 89: on current flow. Estuarine Coastal
Page 90 and 91: Inst. Agric. Res., Tohoku Univ.: 13
Page 92 and 93: In flvt. seayrasses, l'halassia McR
Page 94 and 95: eelgrass (~ostera marina L. ) Phill
Page 96 and 97: along the Strait of Juan de Fuca. N
Page 98 and 99: diatom assemblages in Netarts Bay,

The ecology of eelgrass meadows in the Pacific Northwest: A ...

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?