Patterns of Distribution and Environmental Correlates of Macroalgal Assemblages and Sediment Chlorophyll A in Oregon Tidal Wetlands

Abstract

Algae have important functional roles in estuarine wetlands. We quantified differences in macroalgal abundance, composition and diversity, and sediment chl a and pheophytin a (pheo a) among three National Wetlands Inventory (NWI) emergent marsh classes in four Oregon estuaries spanning a range of riverine to marine dominance. We also assessed the strength of macroalgal-vascular plant associations and the degree to which environmental variables correlated with algal community metrics in marsh and woody wetlands. The frequency of occurrence of most macroalgal genera, total benthic macroalgal cover, macroalgal diversity, and sediment chl a content were several times higher in low emergent marsh than in high marsh or palustrine tidal marsh. Conversely, pheo a: chl a ratios were highest in high and palustrine marsh. Attached macroalgae (Fucus and Vaucheria) were strongly associated with plants common at lower tidal elevations such as Sarcocornia perennis and Jaumea carnosa; Ulva (an unattached alga) was not strongly associated with any common low marsh plants. In structural equation models, intertidal elevation was the most influential predictor of macroalgal cover and richness and chl a; light availability and soil salinity played secondary roles. Although common taxa such as Ulva spp. occurred across a broad range of salinities, wetlands with oligohaline soils (salinity < 5) had the lowest macroalgal diversity and lower sediment chl a. These types of baseline data on algal distributions are critical for evaluating the structural and functional impacts of future changes to coastal estuaries including sea-level rise (SLR), altered salinity dynamics, and habitat modification.

Macrophyte community response to nitrogen loading and thermal stressors in rapidly flushed mesocosm systems

“…At the end of the experiment, we quantified the microalgal flora (MAF) as mg chl a m −2 by scraping a known area of the tank wall, transferring the matrix to a GFF filter that was stored frozen until analysis. MAF chl a was analyzed as outlined by Janousek and Folger (2012) using a Trilogy fluorometer with the non-acidification module (Turner Designs, Sunnyvale, CA). We assume that the MAF community development is analogous to the epiphyte community and use the term to represent both benthic and epiphyte communities.…”

The difficulty of disentangling natural from anthropogenic forcing factors makes the evaluation of ecological quality problematic: A case study from Adriatic lagoons

“…The richness of macrophytes at inter-lagoonal level are also known to be influenced by salinity (e.g. Pérez-Ruzafa et al, 2011;Schubert et al, 2011;Janousek and Folger, 2012) generally showing higher values with higher salinity. Nevertheless, in pristine conditions the few species present have high ecological value, such as angiosperms (Sfriso et al, 2016, and references therein), and this makes the macrophytes a more stable BQE in eutrophic areas with high salinity variations, such as transitional areas.…”

Reproductive Ecology of the Rockweed Fucus distichus in an Urban Estuary

“…While F. distichus has been observed living at the edge of marsh habitats in Northeastern Pacific estuaries, it is most prevalent on natural bedrock and armored shores, especially rip-rap (Dethier, 2010;Janousek & Folger, 2012). The prevalence of hard benthic substrate and wave energy are additional factors that may limit its distribution (Dethier, 2010;Janousek & Folger, 2012;Blanchette, 1997). My observations of F. distichus within Richardson Bay were limited to rocky substrate and it was absent when the substrate transitioned to silty substrate and marshes.…”

“…However, the natural prevalence and ecological importance of rockweed beds in the pre-development history of the SFB remains unknown. In some estuaries of the Northeastern Pacific, including SFB, rockweeds are important spawning habitat for Pacific herring (Janousek & Folger, 2012). They also provide habitat for a variety of small invertebrates that are prey for shore birds and fishes, including juvenile salmonids.…”

“…Invertebrates that live in these macroalgal beds (mussels, oysters, isopods, and shore crabs for example) also support larger consumers higher up the food web (Jones et al, 1994). Macroalgal rockweed Fucus, for example, provides substrate for Pacific herring eggs spawning habitat (Janousek & Folger, 2012). Abundant and dense macroalgal beds can dissipate wave energy stress by protecting organisms from high wave activity higher up the shore (Hurd, 2000).…”