on New Zealand shallow-water foraminifera - Abstract (abridged):
Hayward, B.W.; Grenfell, H.R.; Reid, C.M.; Hayward, K.A. 1999: Recent New Zealand shallow-water benthic foraminifera: Taxonomy, ecologic distribution, biogeography, and use in paleoenvironmental assessment., Institute of Geological and Nuclear Sciences Monograph 21. 258 p.
of brackish water foraminifera
Ten brackish water faunal associations are recognised from cluster analysis of benthic foraminiferal census data (89 species, 131 samples). The associations are characterised by Trochamminita salsa, Haplophragmoides wilberti, Trochammina inflata, Jadammina macrescens, Miliammina fusca, Elphidium excavatum and Ammonia aoteana, on their own or in combinations. Canonical correspondence analysis indicates that the factors most influential in determining the faunal distribution in brackish environments are, in descending order of importance: salinity, tidal exposure, and presence of intertidal vegetation. Associations characterised by agglutinated species occur in the more extreme brackish water environments - in the least saline environments and also above mean high water.
of normal marine salinity foraminifera
Eighteen shallow water (<100 m), normal marine, faunal associations are recognised from cluster analysis of New Zealand benthic foraminiferal census data (327 species, 197 samples). The associations are characterised by various combinations of species of Elphidium, Haynesina, Pileolina, Rosalina, Gaudryina, Notorotalia, Planoglabratella, Quinqueloculina, Cibicides, Zeaflorilus, Virgulopsis, Patellinella, Nonionellina, Trifarina, Bulimina and Cassidulina. Canonical correspondence analysis indicates that the following factors in decreasing order of importance are most influential in determining the faunal distribution in normal marine environments: factors linked to depth, factors linked to wave and current energy, factors linked to biogeography, bottom water oxygen concentrations and substrate type.
Frequency of species
To assess species frequency, species duration and biogeography, we used a data set containing the presence/absence records of 353 species in 50 composite shallow water localities from around the New Zealand region. The frequency of species occurrence follows a log series curve with 35% of the species occurring rarely (1-2 localities) and 20% occurring commonly (>16 localities). Rotaliinid species have the greatest frequency of occurrence (35% are common), whereas lageninids and textulariinids have the greatest number of rare species (44%, 55%). Unlike reported North American results, there appears to be no significant difference in the percentage of endemic or cosmopolitan species that are rare or common.
128 Recent benthic species (36%) have a recorded New Zealand fossil record (50% of rotaliinids, <35% of other suborders). One species first appears in each of the late Cretaceous and Paleocene, 22 in Eocene, 25 in Oligocene, 67 in Miocene, 14 in Pliocene, 4 in Pleistocene, with major influxes in the latest Eocene-early Oligocene, and early Miocene (31 species each). Species with a fossil record have a mean partial species duration of 21 m.yrs. Deeper water species (live dominantly >100 m) have a longer mean duration (24 m.yrs.), than dominantly shallow species (20 m.yrs.) or brackish species (9 m.yrs.).
Commonly occurring species have a far greater percentage with a fossil record (55%) than rarely occurring species (19%). Contrary to findings elsewhere, the rarely occurring species with a fossil record have a longer mean duration (27 m.yrs.) than the intermediate class (21.5 m.yrs.) and the common class (15.5 m.yrs.). 66% of the 50 endemic New Zealand species have a fossil record (mean duration 14 m.yrs.), whereas only 40% of the 180 cosmopolitan species have a New Zealand fossil record (mean duration 25 m.yrs.).
Fifty percent of our species are cosmopolitan, 14% endemic and 10% have a South-west Pacific distribution. All 21 brackish-restricted species are cosmopolitan. There is one endemic genus (Zeaflorilus) and one third of the endemic species belong to three genera - Notorotalia (6 spp.), Pileolina (5 spp.) and Quinqueloculina (5 spp.). New Zealand appears to be the centre of greatest diversity for the former two genera. 38% of the endemic species occur commonly around New Zealand with many as characterising species of faunal associations - Spiroplectinella proxispira, Elphidium novozealandicum, Nonionellina flemingi, Notorotalia finlayi, Pileolina zealandica, Virgulopsis turris, Zeaflorilus parri. All the New Zealand brackish and mid shelf faunal associations occur overseas, but 13 of the 16 normal marine salinity, inner shelf associations appear to be restricted to New Zealand.
A simplified version of the composite locality presence/absence data set on New Zealand's normal marine, shallow water foraminifera was analysed by clustering Jaccard coefficients. Six mappable biogeographic provinces were identified from the resulting dendrogram - Kermadecian, Aupourian (north-east North Island), New Zealand (most of the three main islands), Fiordland, Moriorian (Chatham Islands) and Antipodean (Subantarctic Islands). These foraminiferal provinces are closely similar to the classic, molluscan-defined marine provinces. Diversity decreases from north to south in the well-studied mainland provinces, with 304 species in Aupourian and 270 in the New Zealand. The pattern of brackish water foraminiferal biogeography in New Zealand differs from that of the normal marine species and appears to be more similar to that displayed by terrestrial plants and animals.
A multiplicity of physical and biological factors determine the modern ecologic distribution patterns of foraminifera. The correlation of some of these factors with the presence or abundance of certain foraminiferal taxa or associations has been documented in modern faunas and may be used to assess the paleoenvironment of fossil foraminiferal faunas. The validity of this uniformitarian approach is largely accepted for the Quaternary and Neogene but becomes less reliable going back in time through the Paleogene and Cretaceous.
Fossil foraminiferal faunas can provide assessments, at varying levels of accuracy, of a number of paleoenvironmental factors of value to geological, paleoclimatic and paleoceanographic studies. Planktic foraminiferal percentage, maximum size, encrustation, diversity, coiling ratios and taxonomic census data can be used to estimate oceanicity and paleotemperature and to give an indication of water depth. Benthic foraminiferal diversity and composition by suborder sometimes provide a general indication of the past environment, but the benthic taxonomic composition and recognition of faunal associations allow more detailed assessments of water depth, intertidal level, salinity, exposure to water turbulence, bottom oxygen concentrations, water temperature and carbon flux.
A method for rapid
paleoenvironmental assessment of individual fossil faunas is outlined, based
largely on an estimate of the planktic percentage and identification of the
dominant benthic taxa or faunal association.