Diatoms from two macro-tidal mudflats in Chignecto Bay, Upper Bay of Fundy, New Brunswick, Canada

Abstract

Mudflat research is dispersed among several fields (ecology, sedimentology), each with its own focus and methodology. Consequently, although the volume of mudflat literature is considerable, our understanding of mudflat ecology remains fragmented. For example, little is known about the structure of microbial communities outside Western Europe. Here we present the first North American specific composition and densities of live mudflat diatoms and relate them to properties of their environment on two closely located flats. The two flats (DanielÕs and BuckÕs) were similar until the mid-1980s. After this time the biological and sedimentary environment on BuckÕs Flats began to change and resulted in a precipitous decline of the keystone invertebrate Corophium volutator (Pallas). The specific diatom composition on each of the two flats examined was still very similar. Tychoplanktonic diatoms were numerically dominant on both flats. The flats differed significantly in the relative contribution of epipelic diatoms, which were about an order of magnitude greater on BuckÕs Flats. CCA analysis suggests that very few of these species exist within their optimal habitat. Some of the differences appeared small, but were statistically and biologically significant. DanielÕs Flats sediments had a 30% larger mean grain size, less water and organic carbon compared to BuckÕs Flats sediments. BuckÕs Flats had more variable depths of the oxygenated layer, often with anoxic inclusions throughout. DanielÕs Flats supported more C. volutator, while BuckÕs Flats contained greater densities of diatoms. The importance of preserving environmental conditions (sedimentary and biotic) prevailing on flats such as DanielÕs Flat in order to foster populations of Corophium at a level necessary to support foraging migratory shorebirds is also discussed.

Fatty acid composition and concentration of alternative food of Semipalmated Sandpipers (Calidrispusilla) in the upper Bay of Fundy, Canada

“…This is a surprising result, as diatoms are known to be an important source of FAs (Huggins et al 2004), particularly some longer chain PUFAs (Ackman et al 1964;Dunstan et al 1993), and diatoms make up the majority of microphytobenthos on mudflats in the Bay of Fundy (Trites et al 2005). Concentration and quality of FAs in diatoms varies with season, ultraviolet radiation, light, and species (Dunstan et al 1993;Huggins et al 2004;Guihéneuf et al 2010;Chen 2012), so it is possible that the conditions present on our mudflats are not conducive to high FA concentrations.…”

“…This is not surprising and has also been documented in other areas of their range (e.g., Skagen and Oman 1996). In the Bay of Fundy, both polychaete worms and biofilm (consisting primarily of diatoms and the extracellular polymeric substances that they produce; Trites et al 2005) now appear to contribute substantially to the diet (Quinn and Hamilton 2012), and other prey such as ostracods can be important if present in sufficient quantities (MacDonald et al 2012). The inclusion of biofilm is consistent with recent studies of related shorebird species (Kuwae et al 2008(Kuwae et al , 2012Jardine et al 2015), in which it has been found to be an important dietary component.…”

Pseudo-nitzschia species population dynamics in the Quoddy Region, Bay of Fundy

“…In addition, tidal state (incoming or outgoing) was coded as a pair of nominal response variables (TIDEIN and TIDEOUT, respectively). Statistical analysis was similar to that described in Kaczmarska et al (2000) and Trites et al (2005), but with options more appropriate for this data set. CCA was performed on log transformed [ln(Ay + B); A = 1, B = 1] calculated species cell densities from each sample.…”

Modern diatom assemblages in surface sediments from shallow lakes and streams in southern Pampas (Argentina)

“…It is well known that physical properties of sediments play a fundamental role in the nature of the microphytobenthos assemblage that colonizes sediments (Trites et al 2005). The settlement of large benthic diatom biomasses is prevented in sandier, unstable sediments, where the development of colonies on the open surface of sand grains is inhibited by agitation (McIntire and Ampsoker 1986).…”