Sr. Thorrold et Dm. Williams, MESOSCALE DISTRIBUTION PATTERNS OF LARVAL AND PELAGIC JUVENILE FISHESIN THE CENTRAL GREAT-BARRIER-REEF LAGOON, Marine ecology. Progress series, 145(1-3), 1996, pp. 17-31
Larval and pelagic juvenile fish were collected along 2 transects with
in the central Great Barrier Reef lagoon, Australia, using plankton ne
ts and light traps in October, November and December 1989. Multivariat
e analyses were used to examine spatio-temporal variability in the dis
tributions of the fish collected with both techniques. Plankton nets r
evealed a relatively stable cross-lagoon pattern, with (1) a distincti
ve nearshore component characterized by gobiids, callionymids, leiogna
thids and teraponids; (2) a cross-lagoon group including nemipterids,
carangids, platycephalids and scorpaenids; and (3) an outer-lagoon ass
emblage dominated by clupeids, lutjanids, pomacentrids, and scombrids.
Significant temporal coherence in the abundance patterns of a number
of families with cross-lagoon and offshore affinities was also detecte
d. This coherence could have been generated by either a synchronous sp
awning event, or by hydrographic phenomena acting over synoptic scales
of al least 50 km in both alongshore and cross-shelf directions. Ligh
t trap catches were much more ephemeral than those from the plankton n
ets, and were dominated by collections at a single station in October.
Numbers of principal taxa at this station were variable on each of th
e 3 sampling occasions during the month. The most numerous taxa, Pomac
entrus spp., were captured in high numbers on all of the 3 nights. Let
hrinus spp. and Chromis sp. were abundant on the second night, but low
numbers were taken on the first and third nights. Mullids were captur
ed in progressively higher numbers through the sampling period. Compar
ison of plankton net and light trap data suggested that multi-specific
patches of reef fish larvae were characteristic only of late-larval a
nd pelagic juvenile stages. Patch generation may, therefore, be due to
active aggregation rather than passive accumulation of larvae. Althou
gh the ultimate fate of late-stage larvae within this multi-specific p
atch was unknown, the data are consistent with the hypothesis that maj
or settlement events occur when occasional dense patches of larvae col
lide with reef habitats.