Dark Protein Synthesis: Physiological Response to Nutrient Limitation of a Natural Phytoplankton Population
Satoru Taguchi and Edward A. Laws
Abstract: Dark 14CO2 incorporation into protein was determined from 24-hr incubations using size-fractionated natural phytoplankton populations from Kane`ohe Bay, Hawai`i, enriched with either ammonium or ammonium plus phosphorus. Response to ammonium addition was maximum at an ammonium concentration of 3±4 µM. Dark 14CO2 assimilation was suppressed by addition of both ammonium and phosphorus, but percentage incorporation into protein was not significantly different from addition of ammonium alone. About 75 +/- 1% of the 14C taken up by the cells was incorporated into either protein or low-molecular-weight intermediate compounds. Cells smaller than 10 µm showed little response to nutrient additions. However, cells in the 10- to 35-µm size fraction incorporated significantly more 14C into protein when nutrients were added. C:N ratios calculated from the percentage of 14C incorporated into protein were most variable temporally in the 10- to 35-µm size group and least variable in the picoplankton (0.2- 2.0 µm). Nutrient limitation indices (NLIs) calculated from the quotient of C:N ratios in control and nutrient-enriched cultures were not significantly different for the picoplankton and 2- to 10-µm size fraction. The NLI for the 10- to 35-µm size fraction was significantly lower and implied a modest degree of nutrient limitation. The results suggest that cells smaller than 10 µm are growing at close to nutrient-saturated rates much of the time in Kane`ohe Bay. However, larger cells appear to experience a significant degree of nutrient limitation at some times, particularly when chlorophyll a concentrations are less than about 1 mg m-3. Dark protein synthesis appears to be a useful modification of previous methods based on the dark uptake of 14CO2 for studying nutrient limitation.
Maximum Longevities of Rhizophora apiculata and R. mucronata Propagules
Judy Z. Drexler
Abstract: The longevity of viviparous mangrove seedlings (propagules) in seawater is a key factor determining their ability to survive dispersal both locally and across large expanses of ocean. The purpose of this experiment was to determine the maximum longevities of propagules from two common Pacific mangrove species: Rhizophora mucronata Lamk. and Rhizophora apiculata Bl. Propagules from each of these species were placed in outdoor tubs with continuously flowing seawater. The condition of each propagule was monitored until it sank or started to rot. Propagules were then planted to determine viability. After planting, 50% of R. apiculata propagules and 21% of R. mucronata propagules were viable. For both species, mortality of propagules was strongly related to the length of the floating interval. Maximum longevities for R. mucronata and R. apiculata propagules were 150 (median = 70) and 89 days (median = 7), respectively. Rhizophora mucronata propagules appeared to be better equipped for long-distance dispersal, yet had low survivorship that would decrease overall dispersal opportunities. In comparison, R. apiculata propagules had higher survivorship yet shorter longevity and, thus, appeared to be better equipped for shorter distance dispersal.
Mite (Acari) Communities Associated with `Ohi`a, Metrosideros polymorpha (Myrtaceae), at Hono O Na Pali and Kui`a Natural Area Reserves on Kaua`i Island, Hawaiian Islands
Sabina F. Swift and M. Lee Goff
Abstract: Native `Ohi`a trees (Metrosideros polymorpha) were sampled for mites at two natural area reserves on Kaua`i Island, Kui`a and Hono O Na Pali. Ninety samples of leaves, flowers, bark, leaf litter, and soil under the `Ohi`a canopies were taken. Mites were extracted with use of Berlese-Tullgren funnels. One hundred sixty-four species were found, with the suborder Prostigmata having the greatest number of species (74), followed by Mesostigmata (43), Oribatida (43), and Astigmata with the least (4). Leaf litter, leaf litter with soil, and bark have the most species, composed of predaceous mesostigmatic and prostigmatic mites, but a certain amount of overlap of mite species between the leaf litter and soil habitats was observed. The predominance of Collembola in the soil and litter samples indicates a stable food source for the predaceous mites, partly explaining the high number of mites in those habitats. Oribatid mites were collected from leaves, but the species composition differs from that on flowers and litter. Preliminary residency status of identi®ed taxa shows 12% endemic, 17% adventive, and 71% of unknown status.
First Record of Baseodiscus hemprichii (Nemertea: Baseodiscidae) on Easter Island (Rapa Nui) and a New Eastern Distribution Boundary for the Species
Christopher B. Boyko
Abstract: A single specimen of the nemertean Baseodiscus hemprichii (Ehrenberg, 1831) was collected from Easter Island during August 1999. This represents the first record of the species on Easter Island, the first identified nemertean from that island, and extends the eastern boundary of the species’ range by approximately 4800 km.
A New Species of Mictognathus (Acari: Halacaridae) from the Great Barrier Reef
Jürgen C. Otto
Abstract: Mictognathus colemani Otto, n. sp., is described from the Great Barrier Reef. It is the third known species in its genus and the first species of Mictognathus known to occur in tropical waters. Distinguishing features are dorsal lamellae on the telofemora, membranous flaps on anterior and posterior dorsal plates, lack of distinct areolae or costae, relatively long median claws on all legs, and the lack of corneae. Some of these characters are similar to those of the mictognathine species Corallihalacarus chilcottensis, but it is unknown whether they indicate a close relationship. A key to species of Mictognathus is presented.
Four New Cardinalfishes (Perciformes: Apogonidae) from the Marquesas Islands
John E. Randall
Abstract: Four species of apogonid fishes are described as new from the Marquesas Islands. Apogon lativittatus, similar to A. semiornatus, differs in having 13 instead of 12 pectoral rays, 4.5-5.5 scales above the lateral line, 19-23 circumpeduncular scales, a straighter dorsal profile of the head, deeper body on the average, opaque red color as an adult with the same midlateral blackish stripe posteriorly on the body and caudal fin, but the oblique dark band on head reduced, and in larger size (to 58.4 mm SL); the type specimens include one from the Line Islands (A. semiornatus remains unknown from islands of Oceania). Apogon relativus, with five dark stripes and pink fins, is similar to A. angustatus, differing in having narrower stripes, a larger and vertically elongate black spot at midbase of caudal fin in adults, and a broader interorbital space (bony width 4.05-4.8 in head, compared with 5.0-5.95 for A. angustatus). Apogon sinus, collected in very shallow water at the head of deep bays, is uniquely colored with seven narrow dark stripes on the body, but none on the lower third of body anterior to the caudal peduncle; it is most similar to the wide-ranging allopatric A. taeniophorus, from which it differs in a deeper body (2.6-2.9 in SL, compared with 2.8-3.2), broader interorbital space (4.2-4.45 in head, compared with 4.5-5.35), and in having 16-17 instead of 17-19 gill rakers. Pseudamiops phasma is described from two specimens. Like the three other species of the genus, it is elongate and compressed, with deciduous cycloid scales, no lateral line, ventral spine posteriorly on the maxilla, and largely transparent body; it differs variously from the others, but from all in having 19 compared with 14-18 pectoral rays.
Recent Records of Exotic Reptiles on Pohnpei, Eastern Caroline Islands, Micronesia
Donald W. Buden, D. Brian Lynch, and George R. Zug
Abstract: Seven nonindigenous species of reptiles (two freshwater turtles, one gekkonid lizard, and four snakes) were recorded on Pohnpei and adjacent Ant Atoll (Federated States of Micronesia) for the first time within the past 15 yr, three within the past 3 yr. They apparently reached Pohnpei by deliberate or inadvertent human-assisted transport, originating from widespread and distant areas including North America, Southeast Asia, Indoaustralia, and other Pacific islands. Pohnpeians (and many other Pacific islanders) often do not perceive exotics as a potential threat to the balance of natural ecosystems. Additional training and education addressing the potentially disastrous consequences of alien species and directed especially toward agencies entrusted with monitorin environmental quality are recommended to help preserve biodiversity on these small island nations.
The Somatic Chromosomes of Sophora fernandeziana (Fabaceae), an Endemic Tree from Robinson Crusoe Island
Laura B. Stiefkens, Gabriel Bernardello, and Gregory J. Anderson
Abstract: The mitotic chromosome number and karyotype of Sophora fernandeziana (Phil.) Skottsb. (subfamily Papilionoideae) are reported for the first time. The chromosome number, 2n = 18, is the modal number reported for the genus. The chromosomes are small (average length 1.55 +/- 0.23 µm) and bear no satellites. The intrachromosomal and interchromosomal asymmetry indices were A1 = 0.26 and A2 = 0.18, respectively. This symmetrical karyotype is composed of 7 metacentric + 2 submetacentric pairs. This species is related to S. tetraptera J. Mill. from New Zealand. Both share the same chromosome number; unfortunately comparative karyotype data are not available for S. tetraptera. Our data suggest that no changes in chromosome number have occurred during the speciation of S. fernandeziana, in accordance with previous studies of other endemic species in the Juan Fernandez flora and for island endemics in general. However, only a small percentage of actual karyotypes of island endemics have been studied, so generalizations about chromosomal evolution for such species are not yet well founded.
Mollusk Habitats and Fisheries in Kiribati: An Assessment from the Gilbert Islands
Frank R. Thomas
Abstract: Biological and ecological attributes of 24 species of edible bivalves and gastropods from the Gilbert Islands Group, Kiribati, Micronesia, were assessed for their resilience by examining size at maturity, intertidal burying, adjacent subtidal populations, benthic mobility, and larval type. Foraging for mollusks is largely confined to the intertidal and shallow subtidal regions, although modern diving gear and outboard motors now provide human foragers access to offshore resources. Changes brought about by human demographic pressures have resulted in overexploitation of a number of molluscan resources. It is suggested that the sustainable use of invertebrates and other marine species for food and nonfood purposes in Kiribati rests on a remodeled form of marine tenure.
Pacific Science Assocation