Influence of Patchiness on Modern Salt-Marsh Foraminifera Used in Sea-Level Studies (North Carolina, Usa)

Abstract

We collected replicate samples at stations placed systematically along a transect at Oregon Inlet (North Carolina, USA) to investigate spatial homogeneity of dead assemblages of saltmarsh foraminifera. Analysis of variance (ANOVA) was used to investigate the differences in mean proportions for six species (Miliammina fusca, Trochammina inflata, Arenoparrella mexicana, Tiphotrocha comprimata, Haplophragmoides wilberti and Jadammina macrescens) selected because of their importance in distinguishing assemblages across salt marshes in the study region. As expected, ANOVA's on all species indicated significant differences among low-, middle-, and high-marsh zones defined by their flora. No significant differences were found between stations in the low-and highmarsh indicating homogeneity in these zones. In contrast, for all six species in the middle-marsh zone, significant outcomes for ANOVA, cluster analysis and post-hoc comparisons suggested that the middle-marsh should be divided into two zones. In addition, two species exhibited a patchy (inhomogeneous) distribution among all stations in the middle marsh. If confirmed by additional studies, our results indicate that sampling of modern salt-marshes to document the distribution of foraminifera for use in sea-level reconstructions should recognize the spatial variability associated with the middlemarsh floral zone.

Distinguishing relative specialist and generalist species in the fossil record

“…Within the lowand high-marsh floral zone there was no patchiness of any foraminiferal species. Kemp et al (2011) concluded that "this result supported the validity of our initial assumption of environmental homogeneity in salt-marsh floral zones". Division by cluster analysis of the middle marsh floral zone into two foraminiferal assemblages showed, however, that, while A. mexicana, T. comprimata, H. wilberti and J. macrescens did not have patchy distributions in the middle marsh, M. fusca and T. inflata did.…”

“…If changes in the environment are sufficiently large, generalist species will also change in abundance or entirely disappear. Such studies of modern dead assemblages as that by Kemp et al (2011) are comparable to those of fossil communities, which likewise comprise dead specimens. This paper uses the General Linear Model approach to analysis of variance (ANOVA) to test this ontological assumption (sensu regarding relative specialist and generalist species.…”

“…This is illustrated by marsh foraminifera. Kemp et al (2011) examined the distributions of dead marsh foraminifera [Miliammina fusca (Brady, 1870), Trochammina inflata (Montagu, 1808), Arenoparrella mexicana (Kornfeld, 1931), Tiphotrocha comprimata (Cushman and Brönnimann, 1948), Haplophragmoides wilberti Andersen, 1953, Jadammina macrescens (Brady, 1870] in replicate surface samples from low-, middle-, and high-marsh floral zones along a transect in North Carolina, USA. They investigated the influence of patchiness using unispecies ANOVA for six benthic foraminiferal species.…”

Utility of salt-marsh foraminifera, testate amoebae and bulk-sediment δ13C values as sea-level indicators in Newfoundland, Canada

“…The highest occurrence of foraminifera at Placentia was 0.75 m above MTL (PLA-B station 11) and 257 samples above this elevation on all three transects were devoid of foraminifera (Figure 2 among transects (maximum abundance of <5% on BRM-0, but up to 49% on BRM-1 and 37% on 296 BRM-2) as does Trochammina inflata (maximum abundance of 29% on BRM-0, 2.5% of BRM-1 and 6% 297 on BRM-2), which may reflect a patchy distribution (e.g., Kemp et al, 2011, Swallow, 2000 and/or 298 within site variability of secondary environmental factors such as salinity or sediment texture that were 299 not measured. Modern foraminifera data are presented in the supporting appendix.…”

Paleoenvironmental Evolution of the Restinga of Jurubatiba Lagoons, Rio de Janeiro State

“…In the state of Rio de Janeiro, different works with foraminifera characterize coastal environments (Debenay et al, 1998, Vilela et al, 2004, 2014Uehara et al, 2007, Eichler et al, 2007, Wilson et al, 2008Kemp et al, 2011;Mamo et al, 2013) and its paleo-environmental evolution due to oscillations of sea level (Barbosa et al, 2005;Bruno, 2012;Laut et al, 2012). But in Restinga of Jurubatiba lagoons, few foraminiferal studies have been developed, as this pioneer work will bring contributions for the scientific investigation and for the preservation of this ecosystem.…”