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Systematics and ecology of larvae of lampreys and fishes

Neira, Francisco Javier (1988) Systematics and ecology of larvae of lampreys and fishes. PhD thesis, Murdoch University.

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Abstract

Body intervals, number of trunk myomeres and frequency of pigmentation in different body regions were recorded for populations of larvae of each of the three Southern Hemisphere anadromous parasitic lampreys collected from rivers in Australia, New Zealand and South America. In order to correct for growth, the morphometric data were subjected to multiple group principal components analysis (MGPCA). The components, together with myomere counts and pigmentation data, were subjected to discriminant analyses. Clustering of the discriminant centroids clearly distinguished between populations of Mordacia lapicida from Chile and those of Mordacia mordax from south-eastern Australia. Comparable analyses for Geotria australis suggest that during their marine trophic phase, the adults of this species originating from Argentina and Chile follow different migratory routes, whereas those from Western Australia, New Zealand and Tasmania intermix.

A total of 65,253 larval fish, representing 36 families and 70 species, were collected from surface waters throughout the Swan Estuary between January 1986 and April 1987. Density of many of the most abundant species reached a peak between November and January. The most abundant families were the Gobiidae (88.5%), Clupeidae (3. 5%), Engraulidae (2.3%) and Blenniidae (1.0%). The abundance and distribution of larvae of Nematalosa vlaminghi, Engraulis australis, Parablennius basmanianus, Urocampus carinirosbris, Apoqon rueppellii Atherinosoma wallacei and Amniataba caudavittatus indicate that these species spawn in the upper and/or middle estuary, whereas species such as Hyperlophus vittatus, Parapercis haackei, Callionymus qoodladi and Pelates sexlineabus typically spawn in the lower estuary. Larvae in the lower estuary belonged predominantly to marine species (60%) whose adults are infrequently found in the estuary and to those species which use estuaries and inshore-marine areas as nurseries (21.4%). Although the larvae in the middle and upper estuary represented a small number of species which typically breed within the estuary (14.3%), they accounted for 91.1% of all larvae caught in the estuary. While number of species, diversity and evenness decreased with distance from estuary mouth, the density of larvae was greatest in the upper estuary. The relationships between the above community variables and environmental variables are discussed.

Studies on the early life history of five species from the Swan Estuary indicate that the development of larval Atherinosoma wallacei, Ammniataba caudavitattus and Apogon rueppellii takes place predominantly in the upper estuary between mid-spring and early autumn, whereas that of Gymnapistes marmoratus and Lesueurina sp. occurs in the lower estuary between winter and early spring. While the larvae of all these species are pelagic, they show a variety of developmental and morphological characters which may facilitate their survival and retention within the estuary. These include a large swim bladder and dark body pigment (A. wallacei), extensive head spination and early development of large pectoral fins (G. marmoratus), rapid settlement (A. caudavittatus and G. marmoratus), an advanced stage of development at hatching (A. rueppellii) and an elongated body (Lesueurina sp.).

Item Type: Thesis (PhD)
Murdoch Affiliation: School of Biological and Environmental Sciences
Notes: Note to the author: If you would like to make your thesis openly available on Murdoch University Library's Research Repository, please contact: repository@murdoch.edu.au. Thank you.
Supervisor(s): Potter, Ian
URI: http://researchrepository.murdoch.edu.au/id/eprint/53025
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