Pacific Science, Volume 44, Numbers 1-4, 1990

44: Index - Pacific Science

Mon, 01 Jan 1990 00:00:00 GMT

44:4 Table of Contents - Pacific Science

Mon, 01 Oct 1990 00:00:00 GMT

Plant Water Deficits, Osmotic Properties, and Hydraulic Resistances of Hawaiian Dubautia Species from Adjacent Bog and Wet-Forest Habitats

Canfield, Joan E — Mon, 01 Oct 1990 00:00:00 GMT

Functional responses of two closely related Dubautia species from a mosaic of Hawaiian bogs and wet forest were compared to help explain their differential distributions. Dubautia paleata is largely restricted to saturated bogs, while D. raillardioides is restricted to the surrounding, better-drained wet forest. Minimum diurnal tissue water potentials of D. paleata are significantly lower than those of D. raillardioides, despite the moister condition of bog soil. The tissue osmotic potential at full hydration of D. paleata is significantly lower than that of D. raillardioides. As a result, the tissue water potential at which turgor reaches zero for D. paleata is significantly lower than that of D. raillardioides. Dubautia paleata is thus able to maintain positive turgor to lower water potentials than D. raillardioides. Lack of a lowered, in D. raillardioides may therefore contribute to exclusion of that species from the bog habitat. Preliminary data suggest a significantly greater hydraulic resistance for D. paleata than for D. raillardioides, probably due to higher root resistance caused by the reduced condition of the waterlogged bog substrate. The difference in hydraulic resistance could help account for the contrasting water deficits of the two species.

Revision of the Genera of Gall Crabs (Crustacea: Cryptochiridae) Occurring in the Pacific Ocean

Kropp, Roy K — Mon, 01 Oct 1990 00:00:00 GMT

The coral gall crabs, Family Cryptochiridae, occurring in the Pacific Ocean are reviewed. Fifteen genera, including four new genera, are recognized: Cryptochirus Heller; Dacryomaia, new genus; Fizesereneia Takeda & Tamura; Fungicola Serene; Hapalocarcinus Stimpson; Hiroia Takeda & Tamura; Lithoscaptus Milne Edwards; Neotroglocarcinus Takeda & Tamura; Opecarcinus Kropp & Manning; Pelycomaia, new genus; Pseudocryptochirus Hiro; Pseudohapalocarcinus Fize & Serene; Sphenomaia, new genus; Utinomiella Kropp & Takeda; and Xynomaia, new genus. Host, depth, and distribution records are given for each genus. A key to the females of all gall crab genera is included.

Movement of Coconut Crabs, Birgus latro, in a Rainforest Habitat in Vanuatu

Fletcher, WJ; Brown, IW; Fielder, DR — Mon, 01 Oct 1990 00:00:00 GMT

Patterns of movement in the coconut crab, Birgus latro (L.), were studied using mark-recapture and radio-tracking techniques at a number of sites in the rainforest regions of eastern Santo, Republic of Vanuatu (South Pacific). Movement was assessed both for crabs caught and released in one place (indigenous) and for crabs caught and then released at a new location (introduced). Recapture rates in eastern Santo were very small ( < I%), whereas on the small islet sites (area <2 ha) the rate approached 20%. There were no significant relationships between distance moved and either time at liberty or size of the individuals for introduced crabs. But for indigenous crabs, size of individual was negatively correlated with distance moved. Recapture rates of introduced and indigenous crabs were similar , but introduced crabs moved significantly further from their point of release. Almost all radio-tagged crabs moved from their point of release; smaller crabs tended to move further. On eastern Santo, only two of five radio-tagged crabs were located again ; both had moved over 250-m away from their release point. On the islet sites, all radiotagged crabs were found again at least once; some of these returned to a number of different sites, indicating that B. latro seems to be able to home to particular locations. Nonetheless, dispersal of animals from an area, at least after handling, is a common feature.

Shell Exchange in Hawaiian Hermit Crabs

Hazlett, Brian A — Mon, 01 Oct 1990 00:00:00 GMT

Shell exchange behavior of intertidal Hawaiian hermit crabs was observed in the laboratory. Outcomes of 255 shell-related interactions were analyzed to test the predictive powers of two models of resource exchange. In the case of intraspecific interactions, the negotiations model (which predicts that exchanges should occur only when both crabs will gain in shell value) was superior to an aggression model of resource exchange. In the case of interspecific interactions, the negotiations model accurately predicted outcome of CalcinusCalcinus interactions, but poorly predicted outcome of Calcinus-Clibanarius interactions.

Morphology of the Feeding Apparatus of Cancer novaezelandiae in Relation to Diet and Predatory Behavior

Creswell, Paul D; Marsden, Islay D — Mon, 01 Oct 1990 00:00:00 GMT

Morphology of the mouthparts, gastric mill, and chelae of the New Zealand cancer crab, Cancer novaezelandiae Jacquinot, 1853, was investigated in relation to dietary composition and predatory behavior. Mouthparts and gastric mill were typical of those of other large, predatory brachyurans, with similar structure for male and female, small (60-70 mm) and large (120-130 mm carapace width) crabs. The third maxilliped had large crista dentata, and the inner margin of the mandible was rounded, with a sharp, cutting edge. The large, robust chelae were homeochelous with respect to structure and dental pattern. A large diastema was present and both chela exhibited high mechanical advantage (0.36 and 0.37 for left and right chela, respectively). Relative growth of the propodus was positively allometric, which remained constant throughout crab growth. Morphological features of the feeding apparatus suggested adaptations for macerating coarse, particulate material. This was supported by foregut analysis showing a predominance of sessile and slow-moving macroinvertebrates in the diet. Bivalve and gastropod molluscs followed by crustaceans dominated the diet; fish, sponges, coelenterates, and plant matter occurred less frequently. Little variation in dietary composition was evident with crab sex, size, or season. Cancer novaezelandiae adopted five distinct techniques to open bivalve shells and three techniques to open gastropod shells. These include direct, umbone and posterior crushing, umbone splitting, posterior chipping, and aperture breakage and spire removal. The success of these techniques was dependent upon crab size and prey size and shape. Large crabs were able to use direct crushing over a wider size range of prey than smaller crabs. The structural and behavioral adaptations permit C. novaezelandiae to specialize on mollusc prey and may explain its migrations into areas dominated by molluscan species.

Hawaiian Monk Seal Pupping Locations in the Northwestern Hawaiian Islands

Westlake, Robin L; Gilmartin, William G — Mon, 01 Oct 1990 00:00:00 GMT

Most births of the endangered Hawaiian monk seal, Monachus schauinslandi, occur in specific beach areas in the Northwestern Hawaiian Islands. Data collected from 1981 to 1988 on the locations of monk seal births and of the first sightings of neonatal pups were summarized to identify preferred birth and nursery habitats. These areas are relatively short lengths of beach at the breeding islands and have some common characteristics, of which the primary feature is very shallow water adjacent to the shoreline. This feature, which limits access by large sharks to the water used by mother-pup pairs during the day, should enhance pup survival.

Coastal Geomorphology of the Beqa and Yanuca Islands, South Pacific Ocean, and Its Significance for the Tectonic History of the Vatulele-Beqa Ridge

Nunn, Patrick D — Mon, 01 Oct 1990 00:00:00 GMT

Data referring to elevations of emerged shoreline indicators along the coasts of Beqa and Yanuca islands in southern Fiji were collected and indicate the presence of former mean sea levels at elevations (and shoreline names) of 0.96 m (MUAI), 1.93 m (BULl), 2.63 m (MUA2), 4.32 m (MUA3), 5.94 m (MUA4), and 7.79 m (MUA5) above present mean sea level. No dates for shoreline formation or emergence are available directly although age is believed to increase with increasing elevation. Investigations of the Beqa lagoon floor and comparison of shoreline levels between eastern Beqa, western Beqa, Yanuca, and Vatulele island (at the western end of the Vatulele-Beqa Ridge) suggest that downfaulting along faults and grabens trending a little west of north has occurred both during and since the time of shoreline emergence. Uplift related perhaps to either compression of the area between the Kadavu Trench (Hunter Fracture Zone) to the south and the Fiji Fracture Zone to the north or the renewal of northward underplating along the Kadavu Trench is believed to be responsible for shoreline emergence, which was probably contemporary along the whole Vatulele-Beqa Ridge and occurred during-the middle and late Quaternary.

Review Article: Geology and Volcanology of the Hawaiian Islands

Walker, Geprge PL — Mon, 01 Oct 1990 00:00:00 GMT

This article summarizes the present state of knowledge of the geology of Hawaii. It tends to concentrate on aspects not usually covered by review articles. Current ideas on hotspots and mantle plumes are applied to the specific example of Hawaii, the eight volcanic systems currently nourished by the hotspot are identified, and gross differences in magma-supply rate are related to position of these systems on the hotspot. The important role played by level of neutral buoyancy in distributing incoming magma between magma chambers, rift zones, intrusions, and surface flows is discussed. This is important because volcanic edifices may expand nearly as much by growth of subsurface intrusions as by surface lava outpourings. Recent discoveries, however, show how strongly volcano growth is countered by subsidence and major collapses. A brief description is given of styles of volcanism in Hawaii, and recent ideas on how formation of aa and pahoehoe depends on eruption discharge rate are discussed . A brief summary description pointing to highlights of each volcano is then presented. Finally, I indulge in speculations regarding geographical distribution of the volcanoes and show how, by postulating that a considerable strike-slip motion has occurred on two faults, a much more orderly arrangement of volcano and rift-zone alignments appears, leading to a dynamic model of island-chain growth that is simpler then current models. Proceeding from Kaua'i toward the southeast, an alternating sequence of southeast and west-southwest alignments is revealed. These alignments may be related, respectively, to fractures propagated against the plate motion direction (because of extensional stresses resulting from diverging flow in the mantle plume) and along faults of the Moloka'i fracture zone.

44:3 Table of Contents - Pacific Science

Sun, 01 Jul 1990 00:00:00 GMT

Zooplankton of the Gulf of California after the 1982-1983 El Nino Event: Biomass Distribution and Abundance

Lavaniegos-Espejo, Bertha E; Lara-Lara, J Ruben — Sun, 01 Jul 1990 00:00:00 GMT

From 23 March to 7 April 1984, we studied the responses of zooplankton populations to the 1982-1983 El Nino event in the Gulf of California. Twenty six stations were sampled for zooplankton distribution and abundance. Mean displacement volume was 388 cm3/lOOO m3 , a value higher than biomass values reported for the California Current and the eastern tropical Pacific. Maximum values (up to 60 mg/m3 of dry weight) were registered on the eastern shore of the gulf. At other stations biomass values ranged from 11.2 to 39.2 mg/m3 . No significant differences were observed in the mean biomass of the central gulf between spring 1983 and spring 1984. However, biomass increased in the southern gulf during spring 1984. Mean total abundance of zooplankton was 13% higher than in 1983. Coastal stations registered up to 31% of the total abundance. Copepods and cladocerans represented over 65% of mean total abundance and community structure differed from that in 1983: there were more copepods, euphausiids, tunicates, and siphonophores in 1984, and fewer cladocerans, ostracods, and red crabs (Pleuroncodes planipes). Similarity analysis showed two main assemblages: one in the central gulf (temperate zone), the other near the mouth (tropical zone). These two regions correspond to zones with different physical and primary production characteristics. The different responses seen in the central and southern gulf may reflect phytoplankton biomass and primary productivity dynamics. The El Nino event reduced the biomass in the southern part of the gulf, although the entire gulf in 1983 and 1984 showed higher biomass values than other eastern Pacific systems. Year-to-year differences may be less important than seasonal changes. The EI Nino phenomenon mainly affected the relative abundances of different taxa.

Changes in the Structure and Composition of a New Zealand Lowland Forest Inhabited by Brushtail Possums

Campbell, DJ — Sun, 01 Jul 1990 00:00:00 GMT

All specimens of 19 tree and 11 shrub species greater than 10 cm dbh (more than 3000 stems of trees and tree ferns) were labeled, measured, and mapped in 2.25 ha of lowland forest near Wellington, New Zealand. Their fate, growth, and additional recruitment were monitored in three surveys over 16 yr, from 1969 to 1985. During the vegetation study, movements, diet, density, and breeding success of the introduced Australian brushtail possum (Trichosurus vulpecula) were studied in the same area of forest. In the study plot the number of stems and their total basal area increased between 1969 and 1985. However, several species that are eaten by possums have suffered substantial losses of both stems and total basal area. These include Beilschmiedia tawa, Weinmannia racemosa, Metrosideros robusta, and the tree fern Cyathea medullaris. Species not eaten by possums have increased in both numbers and basal area. These include Hedycarya arborea, Cyathea smithii, Cyathea dealbata, and Laurelia novaezelandiae. During the study there has been a decline in basal area of emergent trees, an increase in basal area of canopy trees (but little increase in their numbers), and an increase in numbers and basal area of minor species and dead trees. If present trends in structure and composition of this lowland forest continue, the future forest will have a greater proportion of tree ferns and more short-lived, small-diameter species. Canopy height and species diversity are also likely to decrease.

Identity of Aralia bastardiana Decaisne

Frodin, DG — Sun, 01 Jul 1990 00:00:00 GMT

Aralia bastardiana Decne., since its written description in 1864 [as Panax bastardianus (Decne.) Decne.] thought to be from Tahiti but never recollected there, is considered almost certainly to have been collected in the Marquesas. It is identical to Cheirodendron marquesense F. Brown, the name by which the Marquesanpimata, the only species of the genus outside the Hawaiian Islands, is usually known. A new combination, Cheirodendron bastardianum, is therefore made. Spirally arranged leaves, seemingly exceptional in Cheirodendron but depicted on the main shoot in Decaisne's illustration of Aralia bastardiana, also occur in juvenile plants and on reversion shoots of Hawaiian species, at least in C. trigynum subsp. helleri and C. platyphyllum subsp. kauaiense. A list of localities and specimens seen of C. bastardianum is given.

Chromosome Counts from the Flora of the Juan Fernandez Islands, Chile. III.

Sun, Byung Yun; Stuessay, Tod F; Crawford, Daniel J — Sun, 01 Jul 1990 00:00:00 GMT

Thirty-four chromosome counts are reported from populations in 20 species from Masafuera in the Juan Fernandez Islands, Chile. New species counts are in Abrotanella crassipes (2n = 18), Carpobrotus aequilaterus (n = 9), Coprosma pyrifolia (n = 22), Drimys confertifolia (n = ca. 43), Euphrasia Jormosissima (n = 44), Parietaria debilis (n = 8), and UrticaJernandeziana (n = ca. 11). A new chromosomal level for Hypochoeris glabra (n = 12) also is provided. The taxonomic implications of certain of these counts are discussed. These data help extend chromosomal information for endemic taxa of the archipelago as part of broad evolutionary studies on the origin of the vascular plants. This study again emphasizes the absence of aneuploid or euploid chromosomal alterations during speciation within the archipelago.

First Central Pacific Plate and Hawaiian Record of the Deep-sea Tripod Fish Bathypterois grallator (Pisces: Chlorophthalmidae)

Jones, Anthony T; Sulak, kenneth J — Sun, 01 Jul 1990 00:00:00 GMT

Two species of tripod fish, Bathypterois grallator and B. cf. atricolor, were observed in the Hawaiian Islands at depths of > 1000 m during submersible dives in May and July 1986. This is the first record of B. grallator in the central Pacific Ocean.

Polychaeta from the Vicinity of Deep-sea Hydrothermal Vents in the Eastern Pacific. II. New Species and Records from the Juan de Fuca and Explorer Ridge Systems

Blake, James A; Hilbig, Brigitte — Sun, 01 Jul 1990 00:00:00 GMT

A total of 15 genera and species distributed in 10 families of Polychaeta is reported from hydrothermal vent sites on the Juan de Fuca and Explorer ridges off British Columbia and Washington. One genus and 10 species are new to science. New taxa include Protomystides verenae (Phyllodocidae), Nereis piscesae (Nereididae), Hesiodeira glabra and Amphiduros axialensis (Hesionidae), Sphaerosyllis ridgensis (Syllidae), Ophryotrocha globopalpata and Parougia wolji (Dorvilleidae), Orbiniella hobsonae and Leitoscoloplos pachybranchiatus (Orbiniidae), and Nicomache venticola (Maldanidae). The hesionid Hesiospina vestimentifera and the ampharetid Amphisamytha galapagensis, previously reported from other eastern Pacific vent sites, are newly recorded. The scalibregmatid Axiokebuita millsi, previously known from deep-sea locations in the North Atlantic and Antarctic, is new to the northeastern Pacific. Additional records of the recently described alvinellid, Paralvinella pandorae, are reported.

Elevated Carbon Dioxide Levels in Bayliss Cave, Australia: Implications for the Evolution of Obligate Cave Species

Howarth, Francis G; Stone, Fred D — Sun, 01 Jul 1990 00:00:00 GMT

In May and June 1985, the deeper passages of Bayliss Cave, North Queensland, Australia, contained up to 200 times the ambient atmospheric level of carbon dioxide and a water-saturated atmosphere, yet supported the most diverse community of highly modified, obligate, terrestrial cave species yet known. The obligate and facultative cave species were mostly segregated by the environment, with the 24 obligate cave-adapted species being largely restricted to the "bad-air" zone. The discovery of this previously unknown "bad-air," obligate cave community corroborates other behavioral and distributional studies that suggest that cave-adapted animals are specialized to exploit resources within the smaller underground 'voids, where fluctuating carbon dioxide concentrations are theoretically intolerable to most surface and facultative cave species.

Geochemical Study of Fumarolic Condensates from Kilauea Volcano, Hawaii

Barnard, Walther M; Halbig, Joseph B; Fountain, John C — Sun, 01 Jul 1990 00:00:00 GMT

Results of a geochemical study based on 20 samples of condensates obtained between late December 1987 and early January 1989 at five fumarole sites on or near the summit of Kilauea Volcano, island of Hawaii, are presented. Fumarole chemistry may be explicable in terms of the currently accepted model of Kilauea and its mechanisms of magma replenishment and storage, degassing, and eruptive activity; it may have potential for forecasting eruptions. Fumaroles emit magmatic and recycled gases and aerosols that enter into Earth's exchangeable reservoirs and which have a potentially harmful impact on health and the environment through release of toxic materials and creation of precipitation and vog of acidic character. Condensates from fumaroles were analyzed by neutron activation/gamma-ray spectroscopy. Concentrations of 28 elements are tabulated and statistically analyzed. Seven elements (As, Ba, K, Sc, Se, V, and W) were in concentrations less than their detection limits; 10 elements (Br, Cr, Cu, Eu, Fe, Hf, Mg, Sb, Sr, and Ti) were below their detection limits in 75% or more of the samples; and II elements (AI, Ca, Cl, Co, I, La, Mn, Na, S, V, and Zn) exhibited significant variation. Individual fumaroles with distinctive ratios of elements and a high degree of correlation between element pairs are identified.

44:2 Table of Contents - Pacific Science

Sun, 01 Apr 1990 00:00:00 GMT