Maximum flood area during MIS 1 in the Almenara marshland (Western Mediterranean): Benthic foraminifera and sedimentary record

The sedimentological and micropaleontological analysis of three mechanical cores in the marshland of Almenara (Valencian Community, Spain) has allowed the reconstruction of the Holocene evolution of this wetland. The cold and dry 8.2-ka event might be represented in Almenara by a massive carbonate precipitation bed, upon which mid- and late-Holocene sediments were subsequently deposited. The direct influence of sea-level changes has been recorded in the two cores (S-4 and S-5) located near the marsh barrier, at 400–450 m from the current coastline. The maximum flood area during MIS 1 (last 11,600 years) is represented in these cores by sediments indicative of different littoral subenvironments (shoreface, foreshore, backshore). These sediments contain typically littoral marine foraminiferal species such as Ammonia beccarii, Rosalina globularis, Asterigerinata mamilla, Adelosina longirostra, Cibicidoides lobatulus, Elphidium macellum, and Bolivina pseudoplicata. The base of these littoral sedimentary materials has been dated as 5480 and 5580 cal. yr BP. At this moment, the inner area (core S-7) was occupied by a restricted oligohaline marsh subject to water-table fluctuations and with scarce individuals of brackish water foraminifera, such as Ammonia tepida, Haynesina germanica, or Cribroelphidium excavatum, that in more recent times (since at least 1700 cal. yr BP) gradually evolved to a palustrine area.

Evidence for Holocene sea level and climate change from Almenara marsh (western Mediterranean)

In the Almenara marsh (western Mediterranean), four cores were analyzed to establish the relationship between the marsh record of the Almenara marshlands and the environmental factors responsible for its evolution during the Holocene. One hundred and eighty-six samples were collected for sedimentologic and paleontological study: 63 for biomarker analysis; 5 for amino acid racemization (AAR) dating; and 5 for 14C dating. Litho and biofacies analyses identified distinct paleoenvironments, with the presence of a marsh environment alternating with inputs of alluvial material and marine sediments. Biomarkers indicated the constant presence of terrestrial (herbaceous) plants, together with a variable development of aquatic macrophytes. During the Holocene transgression, the Almenara marsh was occupied by oligohaline marsh facies with an oscillating water level and peat formation, which was established at the bottom of the record at 7570 cal yr BP and persisted until 3100±780 yr (AAR). Maximum surface flooding occurred at 5480 cal yr BP, registered 450m from the current coastline. At least three peat beds (dated with 14C dating and AAR) correlated with Bond (episode 5900 cal yr BP) and Wanner (episodes 4800–4500 and 3300–3500 cal yr BP) cycles and thus correspond to a regional model that affected the Northern Hemisphere.

Hudson River Fishes and their Environment

<em>Abstract.</em>—We compared nekton density and benthic prey availability over a range of flooding conditions within common reed <em>Phragmites australis </em>and narrowleaf cattail <em>Typha angustifolia </em>at a mesohaline and an oligohaline marsh on the Hudson River Estuary. Nekton were sampled using lift nets at high and low elevations. Marsh surface nekton sampling occurred on 16 high tide events from May–October 1999 and 2000. Hydrology (depth, duration, and frequency) was simultaneously measured. Benthic macroinvertebrate density and richness were measured from sediment cores in June, August, and October, coincident with lift net collections. A total of 690 individuals representing nine species, mostly mummichog <em>Fundulus heteroclitus </em>and daggerblade grass shrimp <em>Palaemonetes pugio </em>were captured within both vegetation types. Mean nekton density (individuals 6 m^-2 ± SE) on the marsh surface was not significantly different among reed at the mesohaline marsh (4.1 ± 1.3) and reed (3.4 ± 0.6) and cattail (4.1 ± 0.9) at the oligohaline marsh. Nekton density did not vary predictably across the measured range of flooding depth and duration. Nekton density was also not predictably related to benthic macroinvertebrate density or taxonomic richness. Significantly more juvenile mummichog were collected within cattail relative to reed, suggesting that spawning success of this species may be lower in reed. Adult resident fish and macrocrustacean species are distributed similarly within and between reed and cattail when they experience comparable flooding regimes. The present study represents one of the first direct measures of nekton density within reed and corroborates previous patterns for nekton abundance between reed and nonreed vegetation stands across a wide salinity regime.