Foraminiferal associations in the upper Waitemata Harbour, Auckland, New Zealand

Abstract

Census data on 68 benthic foraminiferal tests in 56 seafloor sediment samples from the upper Waitemata Harbour, Auckland, New Zealand (36° 50 S, 174° 40 E) are analysed by Cluster Analysis. The faunal samples, taken from extreme high tide to 8 m depth, and from strongly brackish to normal marine salinities, are grouped into 7 associations. Characterising species of each association are found by calculating Association Scores for each species, based on its mean abundance, relative abundance, fidelity, persistence, and dominance within each association.The foraminiferal associations are: JE, Jadammina macrescens-Elphidium excavatum f. clavata -high tidal, sandy mud, in salt meadow and dwarf mangrove swamp, with near normal marine salinity; Tn, Trochammina inflata -around mean high water springs in salt marsh and salt meadow, with variable salinity; M, Miliammina fuscasubtidal channels and intertidal mud banks, mangrove swamp, and salt marsh with reduced salinity; H, Haplophragmoides wilberti -above mean high water, in salt meadow and salt marsh, with slightly reduced salinity; Tr, Trochamminita salsaintertidal sandy mud banks at head of estuary, with lowest salinity; AM, Ammonia beccarii-Miliammina fusca -intertidal and shallow subtidal mud fiats and channels, with near normal marine to slightly reduced salinity; A, Ammonia beccarii -intertidal and subtidal (to 8 m+ depth) muddy sand, with near normal marine to slightly reduced salinity.In the cluster analysis dendrogram of samples, the first-order division produces a three-way split of: (1) near-normal marine salinity agglutinated associations (JE,Tn); (2) low-salinity, agglutinated associations (M,H,Tr); and (3) near-normal marine salinity, calcareous associations (AM,A). The dominant foraminiferal species are grouped by cluster analysis into five species associations; these correlate closely with the sample associations. There is an overall trend of increasing species diversity from brackish to saline and from intertidal to subtidal. This study supports earlier conclusions that salinity and tidal exposure are the two most influential factors in determining foraminiferal distribution patterns in sheltered tidal harbours and estuaries.A common species in the near-normal salinity subtidal channels, Siphogenerina striata, may have been introduced into the harbour with foreign shipping.Keywords: Foraminifera; benthic foraminiferal associations; ecological distribution; Waitemata Harbour; Rangitopuni Estuary; Pollen Island; Auckland; New Zealand; Cluster Analysis; species diversity INTRODUCTIONKnowledge of the ecological distribution of shallow-water benthic foraminifera (Protista, Protozoa) has application in studies of both modern and fossil environments.This study is the fifth part of a six-part programme aimed at documenting the ecological distribution patterns of modern shallow-water (brackish and inner shelf) foraminifera around New Zealand. The programme consists of six quantitative studies -two in each of the * Auckland Institute and Museum, Private Bag 92 01...

Tidal range of marsh foraminifera for determining former sea‐level heights in New Zealand

“…More recently there have been a number of studies on the ecological distribution of brackish and marsh foraminiferal associations in northern (Hayward 1993;Hollis et al 1995;Hayward et al 1997a), central (Hayward &Triggs 1994) and southern New Zealand . The results of these studies and others have been summarised, together with discussion of the taxonomy and biogeography, by and Hayward et al ( 1999).…”

“…HABITAT: In this study, the Ammotium association is mostly recorded from rush salt marsh and from a patch of Samolus salt meadow (F6), although it also occurs beneath mangroves and in unvegetated tidal mud flats elsewhere (Hayward et al 1997a). …”

“…In some more detailed studies the association is split into two separate associations-a Trochammina inflata and a Trochammina macrescen* (=Jadammina) association (Hayward et al , 1997a, with the T. inflata association occurring in higher salinities …”

“…This study was designed to investigate and calibrate previously recognised New Zealand high tidal marsh assemblages dominated by the agglutinated foraminifera Trochammina inflata, T. macrescens and Miliammina obliqua Hayward et al 1996Hayward et al , 1997a.…”

Community Structure and Biodiversity of Soil Ciliates at Dongzhaigang Mangrove Forest in Hainan Island, China

“…Although all major groups of mangrove plants and animals have been studied to some extent [3][4][5][6][7], little information is available on single-celled soil protozoan organisms except a few described species of foraminifera, amoeboid, and ciliated protists [8][9][10][11]. Investigations on soil ciliates in mangrove forest habitats are rare.…”