Biodiversity and community structure of deep-sea foraminifera around New Zealand

Abstract

The biodiversity and community structure of benthic foraminifera were estimated from 217 stations distributed in four geographic regions (north, south, east, west) around New Zealand. An analytical method accumulating sample values of species richness ( S ) , the information function ( H ) and evenness ( E ) with increasing number of individuals ( N ) called SHE analysis was used to establish 16 foraminiferal communities and their community structure at shelf (0–200 m), bathyal (200–2000 m) and abyssal ( > 2000 m ) depths. A decrease in S, H and E occurs from north to south and this latitudinal gradient extends to abyssal depths. An increase in S and H with depth occurs in the northern and southern areas. For ln S , H and ln E against ln N , regression lines on values obtained from SHE analysis at shelf, bathyal and abyssal depths all diverge in the southern area. Each of the other areas exhibits crossing of regression lines so that establishing the rank order of S, H or E with depth within an area requires consideration of N. For a log series pattern, H is a constant proportional to α , the parameter of the log series, and, based on the decomposition equation ln S = H + ln E , a regression of ln S against ln E yields a regression coefficient of - 1 and an intercept of H. At depths of less than 1000 m, 2 of 8 communities have regression coefficient confidence intervals that include - 1 . At depths of greater than 1000 m, 7 of 8 communities intervals include - 1 . Thus, overall, the majority of cases, but especially those at depths greater than 1000 m, have a log series pattern.