Lanternfish (Myctophidae) zoogeography off eastern Australia: a comparison with physicochemical biogeography.

Adrian J Flynn,N Justin Marshall

doi:10.1371/journal.pone.0080950

Abstract

In this first attempt to model the distributions of a mesopelagic fish family at this scale in the eastern Australian region (10°S to 57°S), lanternfish species occurrence data spanning a period from 1928 to 2010 were modelled against environmental covariates. This involved: (1) data collation and taxonomic quality checking, (2) classification of trawls into “horizontal” (presence-absence) and “oblique” (presence-only) types, and classification of vertical migration patterns using existing literature and the species occurrence database, (3) binomial GAMs using presence-absence data for representative temperate, subtropical and tropical species to examine depth interactions with environmental covariates and refine the selection of environmental layers for presence-only MAXENT models, (4) Presence-only MAXENT modelling using data from all trawls and the reduced environmental layers, and (5) Multivariate analysis (area-wise and species-wise) of the resulting matrix of logistic score by geographic pixel. We test the hypothesis that major fronts in the region (Tasman Front, Subtropical Convergence, Subantarctic Front) represent zoogeographic boundaries. A four-region zoogeographic scheme is hypothesised: Coral Sea region, Subtropical Lower Water region, Subtropical Convergence/South Tasman region and Subantarctic region. The Tasman Front, Subtropical Convergence and Subantarctic Front represented zoogeographic boundaries. An additional boundary at ∼25°S (coined the ‘Capricorn’ boundary) was adopted to delineate the Coral Sea from Subtropical Lower Water regions. Lanternfish zoogeographic regions are congruent with some aspects of two prevailing physicochemical biogeographic schema in the region, but neither of these schema alone accurately predicts lanternfish distributions. As lanternfishes integrate vertical ocean processes, the hypothesised lanternfish zoogeography may represent a useful model for a generalised pelagic biogeography that should be tested for other oceanic groups.

Highlights

Lanternfish assemblages are geographically delineated in many ocean regions including the Southern Ocean [1,2,3,4], Canary Islands [5], Humbolt Current region of South America [6], Kuroshio Current region of the northern Pacific Ocean [7,8], Atlantic Ocean [9,10,11], Indo-West Pacific Ocean [12] and California Current region [13]
We aimed to test the hypothesis that lanternfish assemblages in oceanic waters off eastern and southeast Australia are demarcated by major oceanographic frontal systems; namely the Tasman Front (TF), Subtropical Convergence (STC) and Subantarctic Front (SAF)
Data Collation Lanternfish species records spanned the years 1928 to 2010 and were collated from five sources: (1) Museum collection data: Australian Museum, National Museum of Victoria, Queensland Museum, Museum of Comparative Zoology (Harvard University), Natural History Museum of Denmark (Copenhagen); (2) Taxonomic collection data from research institutions: CSIRO Marine and Atmospheric Research (CSIRO) Australian National Fish Collection, Australian Antarctic Division Fish Collection; (3) Lanternfish catch composition data from published papers and fisheries reports; (4) Unpublished lanternfish catch composition data from fisheries (CSIRO) and biodiversity (Australian Institute of Marine Science) surveys; (5) New, previously unpublished, collections made in the Coral Sea [37] and the Tasman Sea abyssal basin [38]

Summary

Introduction

Lanternfish assemblages are geographically delineated in many ocean regions including the Southern Ocean [1,2,3,4], Canary Islands [5], Humbolt Current region of South America [6], Kuroshio Current region of the northern Pacific Ocean [7,8], Atlantic Ocean [9,10,11], Indo-West Pacific Ocean [12] and California Current region [13]. Temperature (at the surface or at depth) and productivity are cited as important predictors of distributions, the mechanisms by which environmental parameters influence distributions are often unclear [14,15,16] Because of this link between species distribution and oceanography, lanternfishes [1,9,12,17,18] and other mesopelagic fishes [14,19,20,21] have been used to derive pelagic biogeographic schema. Condie and Dunn [27] identified a biogeographic boundary at approximately 25uS delineating the Coral Sea from Subtropical Lower Water in the northern Tasman Sea. Longhurst [26] did not recognise a boundary in this area. Condie and Dunn [27] did not recognise a biogeographic boundary associated with the Tasman Front

Objectives

Methods

Results

Conclusion