A Great Lakes Coastal Wetland Invertebrate Community Gradient: Relative Influence of Flooding Regime and Vegetation Zonation

Abstract

Wetland invertebrate community composition is affected by habitat conditions associated with flooding regimes and vegetation characteristics, yet distinguishing among these influential factors is difficult because they tend to co-vary spatially. We studied a Great Lakes coastal wetland invertebrate community along an elevation gradient as Lake Huron water level rose and fell over a three-year period. This hydrologic variation caused changes in the gradient of flooding conditions, while plant zonation remained relatively unchanged. Multivariate analysis indicated that the invertebrate community varied continuously along the elevation gradient, and that it changed substantially within vegetation zones as water level changed. Variation across the gradient decreased because the high-elevation wet meadow community became more similar to lower-elevation communities as a result of upslope expansion in distributions of many taxa, and substantial increases in dominance of a subset of taxa. Invertebrate density increased dramatically with high-water conditions, and diversity decreased in general. Results suggested that invertebrate community composition was influenced by flooding conditions more than vegetation. These results may have important implications for conservation of high-elevation wetland zones as high-water refuges for wet-meadow invertebrates, and for coastal wetland monitoring schemes based on vegetation zones as habitat for particular invertebrate assemblages.

Palustrine forested wetland vegetation communities change across an elevation gradient, Washington State, USA

“…; Keddy & Ellis, 1985;Battaglia, Collins & Sharitz, 2004). Accordingly, the elevation gradient from high to low across which flooding stress increases is a measurable predictor of wetland ecosystem composition, including soil chemistry (Yu & Ehrenfeld, 2010), plant species (Seabloom & Van Der Valk, 2003), invertebrates (Gathman & Burton, 2011) and microbes (Ahn et al, 2009). The primary finding presented here, that forested wetland vegetation composition shifts from generalist, upland species at high elevations to more specialist wetland species at low elevations, aligns with these well-documented studies of how wetland elevation controls ecosystem processes.…”

Beaver-Created Habitat Heterogeneity Influences Aquatic Invertebrate Assemblages in Boreal Canada

“…The combination of emergent and submerged vegetation is often attributed to higher levels of diversity of aquatic invertebrates (Christensen and Crumpton 2010). Despite effects of vegetation on community assemblages (Pollack et al 1988), several studies indicate that flooding regime has a greater influence on species diversity than vegetation alone, with density increasing during droughts and diversity increasing during periods of higher water levels (Jeffries 1994;Navarro-Llácer et al 2010, but also see Gathman and Burton 2011). We also noted this pattern during our study.…”

“…Other measures of diversity might be lower because some species are capable of entering dormancy to resist desiccation (Batzer and Wissinger 1996). As is often seen with aquatic invertebrates, various measures of biodiversity can rebound once water levels rise (Gathman and Burton 2011). Such annual variation in water levels and beaver activity made it important to assess each year independently.…”

“…Key factors are directly and indirectly hydrological in nature and are associated with hydroperiod (Jeffries 1994;de Szalay and Resh 1996;Gathman and Burton 2011), water chemistry (Angradi and Jicha 2010) and vegetation communities (de Szalay and Resh 1996;de Szalay and Cassidy 2001;Kratzer and Batzer 2007). Surrounding landscape (Batzer et al 2004), specific structure and composition of aquatic vegetation (Christensen and Crumpton 2010;Gathman and Burton 2011), and the presence of woody debris (Braccia and Batzer 2001) are additional influences. Under particular conditions, these environmental factors can shape the structure of aquatic invertebrate communities (Van de Meutter et al 2007) and the relative abundance of functional feeding groups (Hawkins and Sedell 1981).…”

Standardized Measures of Coastal Wetland Condition: Implementation at a Laurentian Great Lakes Basin-Wide Scale

“…The position of each zone along this gradient, within each wetland, is primarily governed by sources of naturally occurring disturbance in the form of variation in water depth and wave exposure (Burton 1985;Wilcox and Nichols 2008;Burton and Uzarski 2009;Uzarski 2009). Fluctuations in water levels cause plants, animals and physico-chemical characteristics to shift along this gradient, with different taxa relocating at different rates, depending on their inherent dispersal capabilities (Gathman et al 2005;Gathman and Burton 2011). The persistence of some vegetation zones depends entirely upon minimum levels of wave energy and water-level fluctuations.…”