Distributional Patterns in Assemblages of Attached Diatoms from Yaquina Estuary, Oregon

Abstract

Summer and winter distributional patterns of attached diatoms were investigated in Yaquina Bay and estuary, Oregon. Differences in species composition and diversity of diatom assemblages at selected stations from fresh water just below Elk City, Oregon, to the marine waters of lower Yaquina Bay were released to environmental gradients. A total of 16,475 diatoms from 30 samples was separated into 256 species and varieties, of which 97 were found in only one sample, and 72 were represented by a single individual. The most abundant diatoms in the August samples were Fragilaria striatual var. californica, Melosira moniliformis, M. nummuloides, Navicula mutica, and Synedra fasciculata, while in the February samples Achnanthes no.2 and no.4, Navicula diserta, N. mutica, and Nitzschia frustulum var. perpusilla were dominant. Of the most abundant taxa, Navicula no. 2, N. diserta, N. gregaria, Nitzschia frustulum var. perpusilla, Synedra fasciculata and Thalassionema nitzschioides were the most evely distributed among the stations. The mean species diversity for diatom assemblages sampled in February was slightly higher than for assemblages collected in August. In February the mean specific diversity within a genus was higher and the mean generic diversity slightly lower than in August. In general, differences in assemblages were closely related horizontally to the salinity gradient and vertically to the desiccation and insolation gradients. However, biological factors were more important in accounting for differences among assemblages in the summer than in the winter and these factors were primarily species interactions between diatoms and macro—algae.

The microphytobenthos of Königshafen—spatial and seasonal distribution on a sandy tidal flat

“…The species composition and abundance of microphytobenthos are influenced (in addition to light) by physical factors such as sediment characteristics (Amspoker & McIntire, 1978;Whiting & McIntire, 1985;G~tje, 1992), temperature (van den Hoek et al, 1979, Snoeijs, 1989, and desiccation (McIntire & Overton, 1971). Salinity becomes important to diatoms in estuaries (Van der Werff, 1960;McIntire & Overton, 1971;Amspoker & McIntire, 1986).…”

“…Salinity becomes important to diatoms in estuaries (Van der Werff, 1960;McIntire & Overton, 1971;Amspoker & McIntire, 1986). Also water currents, waves, turbulence and other weather conditions can have a strong impact on the benthic diatom assemblages (Amspoker, 1977;Colijn & Dijkema, 1981;Korte & Blinn, 1983;de Jonge, 1992).…”

“…The toxic substance hydrogen sulphide can be tolerated by many benthic diatom species (Admiraal, 1984). Little is known about interactions between benthic micro-and macroalgae, some indications are given by Huang & Boney (1984) and McIntire & Overton (1971).…”

A brackish diatom, Pseudofrustulia lancea gen. et sp. nov. (Bacillariophyceae), from the Pacific coast of Oregon (USA)

“…Benthic diatoms are important primary producers on surface sediments in intertidal environments and show higher diversity than planktonic floras (McIntire & Overton 1971, Moore & McIntire 1977). Several researchers have described brackish benthic diatom assemblages from estuaries along the coasts of Washington and Oregon (McIntire & Overton 1971, McIntire 1973, Riznyk 1973, Main & McIntire 1974, Moore & McIntire 1977, Amspoker & McIntire 1978, Sawai & Nagumo 2003, Sawai et al 2016.…”

“…Several researchers have described brackish benthic diatom assemblages from estuaries along the coasts of Washington and Oregon (McIntire & Overton 1971, McIntire 1973, Riznyk 1973, Main & McIntire 1974, Moore & McIntire 1977, Amspoker & McIntire 1978, Sawai & Nagumo 2003, Sawai et al 2016. Recent floral and ecological diatom studies in this region have focused on providing modern baseline data to apply in paleoenvironmental reconstructions (Nelson & Kashima 1993, Hemphill-Haley 1995, Sherrod 1999.…”