The Barnacles of Fiji, with Observations on the Ecology of Barnacles on Tropical Shores! B. A. FOSTER 2 ABSTRACT: Twenty species of barnacles are now known from Fiji as a result of recent colIecting. The barnacle fauna has Malaysian affinities, but there are no endemic species. Brief descriptions and notes on habitats are given. The effects of erosion on the shelI are described for the common intertidal species. The distribution patterns of the common intertidal species, except for those of the coral-boring barnacles, are described; and from these the influence of environmental factors on barnacle distribution is inferred. By determining upper lethal temperatures, recording a few environmental temperatures, and comparing these with similar information on temperate barnacles and shores, I have concluded that high temperatures could be a deterrent to the existence of large numbers of barnacles on sun-exposed surfaces oftropical shores. In shaded conditions barnacles can, however, occupy most of the available surface. THE BARNACLES on many temperate shores tribution patterns of barnacles on tropical are welI known and form conspicuous zones shores, and in their greater temperature that vary in extent with the ecological condi­ tolerance. tions on the shore. Ecological information This paper describes the species of barna­ about barnacles on tropical shores is sparse. cles found on the shores of Viti Levu during In the Pacific Ocean, the sessile barnacle 3 weeks' stay at the University of the South faunas ofthe western and eastern seaboards Pacific in May and June 1972. The ecologi­ are distinct (Zullo 1966), but there is stilI cal distribution patterns of the common need for more information on the habitats shore species are described, and, with some and ranges of intertidal barnacles in the is­ observations on the temperature responses lands of the tropical Pacific. ofthe species, are used to discuss the effects Some progress has been made toward an of tropical shore climates on shore biotic understanding of the causes of barnacle zo­ zoning. nation in terms of environmental factors I gratefulIy wish to acknowledge the use (Foster 197Ib). It has been established, for of the facilities of the School of Environ­ example, that desiccation resulting from mental Sciences at the University of the emersion stresses sets the upper limits ofthe South Pacific, and in particular the assis­ zones, but most of this type of work has tance of Dr. D. B. NedwelI of that school. been confined to temperate shores. On trop­ The study was made possible by a grant ical shores one of the emersion stresses from the Auckland University Research -high temperatures-must be more severe Grant Committee. than it is in temperate waters and may be reflected in more restricted intertidal dis- SYSTEMATIC PART The known cirripedes of Fiji now number 'Manuscript received 7 June 1973. 20 species in 12 genera as listed below. Al­ 2Department of Zoology, University of Auckland, though the intertidal shore barnacles of Viti Auckland, New Zealand. Levu were fairly welI sampled, this list does 35 36 PACIFIC SCIENCE, Volume 28, January 1974 not pretend to be complete insofar as the prominent calcareous plates, the carina and whole island group is concerned. Only a few paired terga and scuta, which become of the coral-associated barnacles were col­ eroded apically. The latera and rostrum are lected, as they were not deliberately pur­ absent but sometimes the scales of the sued during the stay. Deep water, pelagic, upper whorl of peduncle scales are elon­ and epizoic species are barely represented. gated between the bases of the terga and scuta and between the bases of the scuta. The truncate appearance of the plates is due Lepadomorpha to their apical erosion. The movements of Lithotrya valentiana (Gray) the plates against the rock whilst the animal Ibla cumingi Darwin is feeding wear the plates and effect the bur­ Lepas anat(fera Linne (recorded by Bor­ rowing (Otter 1937). radaile 1900) Borradaile (1900) recorded Lithotrya Lepas anser(fera Linne pae'(fica (=L. dorsalis according to Sewell Trilasmis amygadalum (Aurivillius) 1926) from Funafuti, and this species is dis­ tinguished from L. valentiana by the pres­ ence of prominent lateral plates on the Balanomorpha capitulum. Octomeris brunnea Darwin Chthamalus intertextus Darwin Chthamalus caudatus Pilsbry FAMILY IBLIDAE Chthamalus malayensis Pilsbry Tetraclita squamosa viridis Darwin Ihla cumingi Darwin Tesseropora pac(fica Pilsbry Tetraclitella divisa (Nilsson-Cantell) Fig. I A-B Tetraclitella multicostata (Nilsson- Cantell) Two specimens were found in crevice Balanus (Megabalanus) tintinnahulum habitats at about midtide level on the occator Darwin breakwater at Laucala Bay. The genus is Balanus (Balanus) amphitrite amphitrite unmistakable because ofthe four fingernail­ Darwin like plates, the terga and scuta, rising from Balanus (Balanus) amphitrite malayensis the chitinous, hair-covered peduncle, the Hoek whole a golden brown in color. Balanus (Conopea) cymh(formis Darwin Nilsson-Cantell (1921) recorded Ibla Creusia spinulosa euspinulosa Broch quadrivalvis from Fiji. Annandale (191 I) Creusia spinulosa acuta Hiro cautioned on the identification of I bla Pyrgoma milleporae Darwin species, citing one case of misidentification of the sexually differentiated I. cumingi for the hermaphrodite I. quadrivalvis. Hiro SUBORDER LEPADOMORPHA (1936) accepted Nilsson-Cantell's identifi­ cation of Fijian Ibla when considering the FAMILY SCALPELLIDAE geographic distribution of the genus. In view of more recent ecological accounts of Lithotrya valentiana (Gray) Australian shores (e.g., Endean, Kenny, Fig. 1 C-D and Stephenson 1956), which reveal that I. quadrivalvis occurs on cool temperate New This barnacle lives in oval holes up to lOx South Wales shores and that I. cumingi 7 mm in diameter in coral boulders at the occurs on the tropical Queensland shores edge of the reef. From above, and when the with no overlap ofthe species, the existence animal is withdrawn into the hole, the deep of the former species in Fiji seemed doubt­ locking fold between the terga and scuta can ful. be seen (Fig. I D). The capitulum has five To check on the Fijian record, I searched The Barnacles of Fiji-FoSTER 37 G FIG. I. Lepadomorpha: A-B, lateral and rostral views of Ihla cllmingi: C-D. lateral and apical views of Lithotrya wl!entiana: E-F. lateral and carinal views of Lepas anser((era: G, lateral view of Temnaspis amygadaillm. Scales in millimeters. likely habitats for 1bla. Only two specimens Numerous specimens were found were found, both without a penis and with stranded in Laucala Bay attached to drift­ caudal appendages only a little longer than wood. Lepas anser(fera is not easily distin­ the protopod of the sixth cirrus. The availa­ guished by external features from L. anati­ ble data indicate that it is zoogeographically fera, which was also recorded from Fiji by more plausible for only I. cumingi to occur Borradaile (1900), but can be identified by in Fiji. the number of filamentary processes on the protopod ofthe first cirrus and on the side of FAMILY LEPADIDAE the prosoma. In L. anser(fera there are five such processes, but in L. anat(fera there are Lepas anser(fera Linne only two on each side. Other species of Fig. I E-F Lepas probably also occur in Fijian waters. 38 PACIFIC SCIENCE, Volume 28, January 1974 FAMILY POECILASMATIDAE the barnacle grows and enlarges, the orifice through which the cirri are protruded needs Trilasmis (Temnaspis) amygadalum also to enlarge, and this is primarily effected (Aurivillius) by attrition of the older apical parts of each plate, including the upper margins of the Fig. 1 G alae and radii. Some barnacles, particularly those ofsublittoral habitats, also enlarge the Numerous specimens were found on the orifice by the diametric growth of the alae mouthparts of a palinurid lobster taken at a and/or radii. depth of20 feet offBulia, Kadavu, and they The individual shell plates are identifi­ are now in the collections of the University able. In Octomeris, the lateral plate is the ofthe South Pacific. The specimens range in largest and the carinolaterals and rostrolat­ size from about 1to 9 mm capitulum length. erals are placed between the laterals and the Three small specimens were also found on unpaired carina and rostrum. In the mouthparts of the lobster Palinurus ver­ Chthamalus there are but six parietal plates, sicolor taken off Nasese Point, Suva. and the arrangement is broadly comparable Some species of Trilasmis, namely those to Octomeris except for the lack of the of the subgenus Poecilasma, are externally carinolaterals. Thus in Chthamalus the similar to Lepas, but details oftheir appen­ smaller of the lateral plates is situated next dages as well as of their habit-living at­ to the rostrum and overlies the alae of both tached to benthic invertebrates-distin­ the laterals and the rostrum. The possession guish them from the pelagic lepadids. In the ofa distinct rostrolateral plate characterizes subgenus Temnaspis the scutum is secon­ the intertidal Chthamalidae. darily split, giving a total of seven capitular In the Balanidae, Balanus also has six plates. T. amygadalum has been recorded shellplates, resulting from the fusion of the on palinurid decapods from Madagascar rostrum and rostrolaterals. The smallest through Malaysia to Hawaii (Pilsbry 1927, plate is the carinolateral which overlaps the Nilsson-Cantell 1938). alae of the carina but is itself overlapped by the radius ofthe lateral. In many species of Balanus the shell plates have longitudinal. SUBORDER BALANOMORPHA tubes which arise by the folding ofthe inter­ Balanomorph barnacles are particularly nal plate surface. In Creusia the carino­ characteristic of intertidal surfaces. They laterals are not developed, and the shell has are prone to desiccation and erosion, al­ four plates. In Pyrgoma, the shell plates are though these environmental stresses are concrescent as solid shell. Creusia and somewhat mitigated by the growth of the Pyrgoma are both coral symbionts.