Pacific Science, Volume 31, Numbers 1-4, 1977

Vegetation and Urbanization on Majuro Atoll, Marshall Islands

Sabath, Michael D — Sat, 01 Oct 1977 00:00:00 GMT

The urban and nonurban vegetation on the Micronesian atoll of Majuro is described, including changes in forest canopy, understory shrubs, yards, and cultural features since urbanization began in 1944. Currently, the nonurban areas are covered with Cocos nucifera (coconut) groves mixed with smaller Artocarpus altilis (breadfruit) groves, which were probably established in the late 1800s. Indigenous vegetation is limited to a narrow band along the ocean or lagoon shoreline, or as minor understory species in the Cocos-Artocarpus groves. A United States military base was established in 1944 on three eastern islands of the atoll (Uliga, Dalap, and Djarrit). This has subsequently been developed into a major administrative and commercial center for the Marshall Islands. Urbanization on Uliga, Dalap, and Djarrit has resulted in reduction of tree canopy; establishment of extensive yards with grasses, herbs, and sedges; and reduction of many indigenous and aboriginally introduced understory species. Nevertheless, some aboriginally introduced and indigenous species remain in the urban areas as important species (Cocos, Artocarpus, and Tournefortia), with many being actively propagated. Ornamental species, which have expanded in importance, especially in the shrub layer, consist primarily of species recorded in Laura village prior to urbanization. The urban plant community is a mixture of indigenous, aboriginally introduced, and recently introduced species. Future urban expansion is predicted with commercial and residential development replacing horticultural forests along the southern islands of the atoll.

31: Index - Pacific Science

Sat, 01 Jan 1977 00:00:00 GMT

Bryozoa from Cost Rica

Banta, William C; Carson, Renate JM — Sat, 01 Oct 1977 00:00:00 GMT

Twenty-three species of cheilostomes and one cyclostome from two localities on the Atlantic and Pacific sides of Costa Rica are described and illustrated. Two-thirds (16) of the species are considered poorly understood taxonomically. The bryozoan fauna of tropical America is probably less well understood than the literature suggests. Discussions of special interest are those ofthe genera Membranipora, Parellisina, Labioporella, Schizoporella, Escharina, Cigclisula, and Rhynchozoon, and of the higher taxa Bryozoa, Ectoprocta, Gymnolaemata, Eurystomata, Anasca, Ascophora, and Cyclostomata.

Manganese Crusts and Nodules from the Hawaiian Ridge

Glasby, GP; Andrews, JE — Sat, 01 Oct 1977 00:00:00 GMT

Manganese stains, crusts, and nodules are widely distributed on the insular slopes of the Hawaiian ridge. The thickness of the manganese crusts depends on depth of water, water circulation, and the age and lithology of the substrate, and varies from absent to stains off the island of Hawaii to a maximum of 5 cm in the vicinity of Midway. Scanning electron microscope studies indicate that the internal structure of the manganese crusts is relatively featureless compared with that of deep-sea manganese nodules. Reconsideration of ages of manganese deposits from the Hawaiian archipelago indicates that the rates of accretion of manganese crusts are probably in the same range as those of deep-sea deposits and that the crusts do not accrete at a much faster rate than deep-sea deposits as previously suggested. Iron staining is observed in the volcanic substrates and becomes more apparent with the increasing age of the substrate. There appears, however, to be no evidence that iron oxide is a ubiquitous control factor in initiating manganese crustal growth. Because of the terrain and the rocky nature of the substrate, diagenetic processes within the sediment column probably play no major role in controlling the composition of manganese crusts on the flanks of the island ridge.

Taxonomic Status, Biology, and Distribution of Hawaiian Lentipes, a Diadromous Goby

Maciolek, JA — Sat, 01 Oct 1977 00:00:00 GMT

Three species ascribed to the goby genus Lentipes include two from Hawaii, L. concolor (Gill 1860) and L. seminudus Gunther (1880), and one from the Gulf of Guinea, L. bustamantaei Boulenger (1916). The Hawaiian species were described from single specimens of different sex. Specimens collected recently provide evidence that Hawaiian Lentipes comprise a single, sexually dimorphic species. The African species differs significantly and more nearly resembles Sicydium. Lentipes now must be considered a monotypic genus (L. concolor) endemic to the Hawaiian archipelago. The genus is distinguished by weak scalation (2-150 cycloid scales per side on posterior trunk), five subequa1 and one shorter spine in the first dorsal fin, 16 pectoral rays, and one projecting ossified gill raker on the first arch. The sexes differ mainly in head shape, relative mouth size, dentition, spacing of dorsal fins, and coloration. The female is drab; the male is yellow to red posteriorly and has a white anal fin margin. Adult Lentipes, omnivorous and growing to nearly 140 mm TL, inhabit pristine steep-gradient streams. Larvae develop in the ocean and appear at stream mouths as post1arvae less than 20 mm 10ng.Upstream'migrants are capable of ascending high waterfalls, where they reach areas of permanent residence. Surveys located Lentipes in 22 streams (6 percent of the total streams in the archipelago) but the goby was abundant in only a few of them. Because of sparse Lentipes populations and incompatibility with past and continuing habitat degradation, endangered status recognition is recommended.

Cyclopoid Copepods (Lichomolgidae) Associated with Hydroids in the Tropical Western Pacific Ocean

Humes, Arthur G — Sat, 01 Oct 1977 00:00:00 GMT

Eight poecilostome copepods, two of them new, are reported from shallow-water hydroids at various points around Banda, Ceram, and Halmahera in the Moluccas and near Noumea in New Caledonia. From Aglaophenia cupressina Lamouroux: Macrochiron angulare n. sp.; M. cheliferum (Thompson & A. Scott, 1903); M. valgum Humes, 1966; M. vervoorti Humes & De Maria, 1969; and Telestacicola sertus n. sp. From Lytocarpus balei Nutting: M. lobatum Humes & De Maria, 1969. From Lytocarpus philippinus (Kirchenpauer): M. lytocarpi Humes, 1966 and M. rostratum Humes, 1966. These records comprise two new hosts and five range extensions from Madagascar.

31:4 Table of Contents - Pacific Science

Sat, 01 Oct 1977 00:00:00 GMT

Environmental Impact on a Samoan Coral Reef: A Resurvey of Mayor's 1917 Transect

Dahl, Arthur L; Lamberts, Austin E — Fri, 01 Jul 1977 00:00:00 GMT

Coral reef sites in Pago Pago Harbor, American Samoa, for which descriptions and quantitative data were obtained by Alfred G. Mayor and the Carnegie Institution of Washington expeditions of 1917-1920, were resurveyed in 1973. Some sites were destroyed and others damaged in the intervening half century, but it was possible to relocate the major quantitative transect at Aua. A reduction in total numbers of corals, a change in the relative proportions of different genera, and a probable reduction in the average size of individual colonies are recorded. Elsewhere in the harbor, more drastic effects on the reefs were noted. Both human and natural impacts may be responsible for the observed changes; it is suggested that the Aua reef may now be recovering from earlier damaging events.

Contributions to the Mineral Chemistry of Hawaiian Rocks. VI. Olivines in Rocks from Haleakala and West Maui Volcanoes, Maui, Hawaii.

Fodor, RV; Keil, Klaus; Bunch, TE — Fri, 01 Jul 1977 00:00:00 GMT

Phenocryst and groundmass olivine in 22 rocks of the tholeiitic, alkalic, and nephelinicsuites from Haleakala and West Maui volcanoes were analyzed by electron microprobe. Results and conclusions: Ranges for average compositions of olivine phenocrysts and groundmass are, respectively. Fo73 _85 and Fo61 for the tholeiitic suite (only one tholeiite contained groundmass olivine); Fo54_83 and Fo15_68 for the alkalis suite; and Fo73 _83 and Fo61 _66 for the nephelinic suite. In all suites, zoning extends these ranges substantially. Phenocrysts are usually enriched in Fe, Mn, and Ca at their rims, and coexisting groundmass olivine is richer in these same elements and depleted in Cr and Ni contents. In the differentiated alkalic suite, Fe, Mn, and Ca increase, and Ni decreases, from basalt to trachyte (mainly dependent on major element fractionation). The tholeiitic and nephelinic suites can occasionally be distinguished by higher Ca and lower Ni in olivine of the latter.

A Fossil Garcinia Fruit from the New Hebrides, Melanesia

Fosberg, FR — Fri, 01 Jul 1977 00:00:00 GMT

31:3 Table of Contents - Pacific Science

Fri, 01 Jul 1977 00:00:00 GMT

An Analysis of Some Meristic Characters of the Staghorn Sculpin Leptocottus armatus Girard

Morris, Robert W — Fri, 01 Jul 1977 00:00:00 GMT

Over a 4-year period, juvenile specimens of Leptocottus armatus were collected annually at nine stations along the Pacific coast from approximately 37 to 47° N latitude. Collecting was repeated at intervals at two stations (43°24' N and 44°36' N) during the seasons in which young fish were arriving from the plankton. Meristic character counts are similar over the northern part of the range studied, but there is a well-defined cline in conditions south of 43° N. The number of spines on the dorsal fin appears to be influenced very little by natural developmental conditions, if at all. At the two stations sampled at approximately monthly intervals, well-defined seasonal trends in meristic character counts appear to be related to thermal history. Freedom of independent expression of meristic characters in response to the natural developmental environment is restricted by timing of phenocritical periods and a factor of a more fundamental nature, presumably genetic.

Coral-Crab Commensalism in Xanthids

Lamberts, Austin E; Garth, John S — Fri, 01 Jul 1977 00:00:00 GMT

Report of a coral-crab commensalism is described. Xanthid crabs of the genus Actumnus apparently select pieces of live coral for construction of a cover they can move from place to place. The crabs protect the shelter and serve to disseminate the coral locally.

Hybrid Hibiscadelphus (Malvaceae) in the Hawaiian Islands

Baker, James K; Allen, Suzy — Fri, 01 Jul 1977 00:00:00 GMT

First- and second-generation hybrids of Hibiscadelphus giffardianus Rock and H. hualalaiensis Rock have been found in Hawaii Volcanoes National Park, and elsewhere in the Hawaiian Islands. They are under cultivation from interspecifically cross-fertilized seed which occurred on parent trees within the park. A history of parent and hybrid species is given, and floral characteristics are analyzed. Hybrid occurrence and the implications to natural resource management in trying to preserve the integrity of native Hawaiian species and ecosystems are discussed.

Low Seabird Densities in the Pelagic Environment of the Strait of Georgia, British Columbia

Robertson, Ian — Fri, 01 Jul 1977 00:00:00 GMT

Seabird surveys in the pelagic environment of the Strait of Georgia, British Columbia, indicated an exceptionally low annual average density of 3.16 seabirds per km2 when compared to similar estimates of seabird densities in other south coastal British Columbia waters. In spite of a wide (20-km) pelagic zone the avifauna lacked most of the open ocean species and in fact was typical of the inshore protected waters of British Columbia. Two possible explanations were considered. First, though the biological productivity of the study area is not low the apparent absence of suitable foods, particularly adult Pacific herring, Clupea harengus pallasii (Valenciennes), may explain the low seabird numbers. Second, the discharge of the Fraser River which creates a highly turbid layer of surface water may seriously limit the effectiveness of visual predators.

A New Species of Peroderma Heller (Caligoida: Lernaeoceridae), Parasitic on the Fish Bregmaceros japonicus Tanaka

Izawa, Kunihiko — Fri, 01 Jul 1977 00:00:00 GMT

Two female specimens of parasitic copepods found on the fish Bregmaceros japonicus Tanaka, taken on the Pacific coast of Japan, represent a new species, which is described under the name of Peroderma pacifica n. sp.

Note on Cryptodromiopsis tridens (Brachyura, Dromiidae)

Eldredge, LG — Fri, 01 Jul 1977 00:00:00 GMT

Population Biology of the Japanese Little-neck Clam, Tapes philippinarum, in Kaneohe Bay, Oahu, Hawaiian Islands

Yap, Wilfredo G — Fri, 01 Jul 1977 00:00:00 GMT

The Japanese little-neck clam, Tapes philippinarum, an introduced species in Kaneohe Bay, Oahu, Hawaiian Islands, has a thriving population only in a U5-hectare mud flat after heavy fishing triggered depletion in six other beds within the bay. Monthly gonad examination of the clams suggested that spawning occurs at a low level throughout the year with a peak from January to February. This observation is corroborated by the appearance of new recruits in the monthly sample from April to June and by their presence at low levels at other times of the year. Size-specific fecundity, determined indirectly from differences in the length: dry weight relationships of ripe and spent clams, ranges from 432,000 eggs in a 20-mm clam, increasing exponentially to 1.35 x 106 eggs in a 40-mm clam. Estimates of the population of clams 11 mm and larger, which were 3.09 x 106 in 1970 and 3.4 x 106 in 1972, show a growth of 5 percent per year during the 2-year period; monthly quantitative sampling showed no evidence of population growth after 1972. A survivorship curve obtained from the monthly samples gave a total instantaneous mortality of z = 0.2005. The age-specific mortality agrees with the age-frequency of the empty shells collected from the bed, with a correlation coefficient of 0.9345 with 4 d.f. The condition of the empty shells indicated that 57 percent of the mortality is attributable to crab predation, mainly by Thalamita crenata, which constitutes 70 percent of the experimental crab catch in the clam bed. Sixty percent of the broken shells were 19.5 to 30.4 mm in length; in experiments with predation by T. crenata, 96 percent of those eaten fell within the 14.5 to 30.4 mm size range. The difference between the lower limits of the size ranges can be attributed to the size structure of the clams during the survey period. The experimental population had an artificially maintained size structure. Experimental exclusion of predators over a limited area suggested that crab predation regulates clam size structure but not clam density.

Contributions to the Mineral Chemistry of Hawaiian Rocks. V. Composition and Origin of Ultramafic Nodules and Megacrysts in a Rhyodacite from Oahu, Hawaiian Islands

Fodor, RV; Keil, Klaus; Bauer, GR — Fri, 01 Apr 1977 00:00:00 GMT

Dunite nodules (Fo85) and megacrysts of olivine (Fo83 - 84 ) and clinopyroxene (FS13 Wo43 En44) are present as rare inclusions in the rhyodacite ( ~ 66wt%SiO 2 ) of Kauaopuu Ridge, Oahu, Hawaii. The rhyodacite is interbedded with caldera-filling tholeiitic lavas of the Waianae volcano. Results: (I) Dunite nodules (< 1 cm) consist of xenomorphic-granular olivine and minor chrome spinel and clinopyroxene (Fs6 Wo47 En47); olivine (~Fo85) reacted with the rhyodacite magma to form amphibole and an Fe-enriched margin (~Fo80). (2) Olivine megacrysts (2-6 mm) contain chrome spinel and melt inclusions; they are resorbed and rarely are slightly enriched in Fe at the margins. (3) Clinopyroxene megacrysts (0.5-1.2 cm) contain ilmenite, ferropseudobrookite, and melt inclusions; they are slightly resorbed and enriched in MgO at unresorbed margins. Conclusions: (1) Olivine from the dunite and olivine megacrysts compositionally resemble olivine in typical dunite inclusions in alkalic olivine basalts of Hawaii, as well as olivine phenocrysts in basalts of Hawaii. Clinopyroxene in the dunite resembles that in typical dunite inclusions of Hawaii, whereas clinopyroxene megacrysts are like phenocrysts in basalts of Hawaii. (2) The reaction relationship between the dunite and the rhyodacite magma suggests that the nodules are accidental. A positive gravity anomaly over Waianae volcano indicates a dense, perhaps olivine-rich zone beneath the volcano-a possible source for the nodules. (3) The resorption of the megacrysts and their compositions indicate that they are probably remnant phenocrysts of basaltic magma from which the rhyodacite formed by igneous differentiation. (4) Rhyodacite magma was derived from a basaltic parent and it later incorporated dunite fragments, probably during ascent.

The Genus Pittosporum (Pittosporaceae) on Rapa Island and on the Austral Islands, Polynesia Pacific Plant Studies 31

St. John, Harold — Fri, 01 Apr 1977 00:00:00 GMT