RADULAR PRODUCTION RATES IN TWO SPECIES OF LACUNA TURTON (GASTROPODA: LITTORINIDAE)

The molluscan radula is a dynamic organ, both in terms of itsuse and production. New rows of teeth are constantly producedat the posterior end of the radula, while older, worn teethare shed anteriorly, producing a dynamic equilibrium. We useda cold-shock to mark the radular ribbon and measure tooth rowproduction rates in two gastropod species, Lacuna vincta (Montagu)and L. vanegata Carpenter. We found that the average tooth rowproduction rate at 10–11°C did not differ betweenthese two species, and was 2.94 (SE = 0.002) rows per day forLacuna vincta and 2.97 (SE = 0 002) for L. vanegata Inter-individualvariability in production rate was very low, and was correlatedwith shell length, smaller individuals had slightly higher productionrates. The total length of the radular nbbon varied greatlyamong individuals, ranging from 47 to 94 (2.57 to 5.68 mm) rowsin L vincta and 53 to 99 rows (2.80 to 7.14 mm) in L vanegata,and was only somewhat correlated with the length of the shelLThis great variability will result in large differences amongindividuals in the time it takes to replace the radula totally,from 14.96 to 35.44 days in L vincta and from 17 43 to 39 69days in L. vanegata. (Received 1 September 1995; accepted 20 November 1995)     

THE EGG MASS OF LITTORINA OBTUSATA AND LACUNA PALLIDULA (GASTROPODA : PROSOBRANCHIA)

The egg masses of Littorina obtusata and of Lacuna pallidulahave been compared with regard to size, shape, egg number, eggsize and substratum. The structure and histochemistry of thespawn of the two species has been investigated and observationson the laying process in L. obtusata are also recorded. ^* Present address: Portway School, Penpole Lane, Shirehampion,Bristol, BS11 0EB. (Received 12 October 1977;     

Energy flow and breeding in two species of Lacuna: comparative costs of egg production and maintenance

Lacuna pallidula and L. vincta are small intertidal/subtidal prosobranch gastropods, feeding on macroalgae. Both are semelparous annuals, but while L. pallidula is an in situ breeder with low powers of dispersal, L. vincta has a planktotrophic larva. Data have been obtained on the growth, egg production and respiration of these snails under controlled conditions in the laboratory. These data allow the construction of partial energy budgets showing how energy is allocated to the three functions. Allocation and turnover estimates of reproductive effort are discussed in the context of the life cycles of the two species of snail.     

Description of Rhynchoteuthion larvae of Illex argentinus from the summer spawning subpopulation

The Rhynchoteuthion larvae of Illex argentinus resulting fromsummer spawning in North Patagonic shelf waters, its distributionand abundance, are described in this paper. The material wascollected in the Argentine Sea (35–55°S) by meansof plankton nets. The research cruises were made by the R/VShinkai Maru and the R/V Walther Herwig during the period April1978 to April 1979. The most important spawning ground of thesummer spawning subpopulation is found in continental-shelfwaters (between 43 and 46°S) during the period December-February.This area was established on the basis of both ripe (December)and spent females (February). The larvae which were caught duringthe same period, especially in March, confirmed the spawningarea of this demographic unit. The larvae showed the lengthof the mantle (ML) to be from 1.2 to 6.5 mm. Tentacles weresplitting in specimens from 5.0 to 6.5 mm ML (transition stage).When 7.0 mm ML or more, all specimens were juveniles and hadtheir tentacles completely separated. Larvae were characterizedas type C, following the proposal of Sato (1973) and Sato andSawada (1974) in the Bulletin of the Shizuoka Prefectural FisheriesExperimental Station.     

Seasonal and year-to-year variations in the growth of Zostera marina L. (eelgrass) in the lower Chesapeake Bay

Seasonal and year-to-year variations in the growth of Zostera marina L. were measured at three sites in two locations in the lower Chesapeake Bay between 1978 and 1980. The maximum values for the 1979 above- and belowground standing crop ranged from 161–336 g dry wt m⁻² and 61–155 g dry wt m⁻², respectively, leaf length was 19.6–59.7 cm and shoot density 1418–2576 shoot m⁻². Values for 1980 tended to be greater and may be related to climatical differences between the two years. Maximum values were usually recorded in the months of June and July when water temperatures were between 20 and 25°C. Significant loss of leaves occurred in July and August, when water temperatures ranged between 25 and 30°C, while new shoots began to appear more rapidly in late September as water temperatures dropped below 20°C. The greatest increase in all growth parameters occurred from April to June during which time reproductive shoots were present, and accounted for up to 25% of the total number of shoots.     

ALLOZYME COMPARISON OF LITTORINA SPECIES FROM THE NORTHWESTERN PACIFIC

Three unknown Littorina species were revealed by allozyme studyof snails from the northwestern Pacific. One of them was foundin Kasatka Bay (Pacific coast of Iturup Island, south KurileIslands) together with L. sitkana, which it resembled in anatomicalfeatures, but the genetic distance between these species wasD=0.622. The second one was found in Tauiskaya Inlet (northernpart of Okhotsk Sea) and was again similar to L. sitkana inmorphological and anatomical features, but D=1.160. The thirdspecies was found in Egvekinot Inlet (Anadyrskiy Gulf, BeringSea) in sympatry with L. natica, to which was close genetically(D=0.256) although it differed in shell shape. (Received 4 April 2005; accepted 26 August 2005)     

Seasonal variations in plasma concentrations of 11-ketotestosterone and testosterone in male rainbow trout, Salmo gairdnerii Richardson

Measurements were made of plasma 11-ketotestosterone and testosterone in control and sex-reversed male rainbow trout, before and during their first spawning season (winter 1978/1979). Plasma concentrations of both androgens (in both groups) were 2–3 ng ml^-1 in January 1978 (apart from some precocious spawners), rose slowly to 9–11 ng ml^-1 in April and July and then increased rapidly to 100–150 ng ml^-1 in November. From this time, testosterone levels declined but those of 11-ketotestosterone continued to rise to a peak of 260 ng ml^-1 in February 1979. No significant differences in hormone levels were found between control male and masculinized female fish.     

INTRASPECIFIC AND INTERSPECIFIC VARIATION IN SHELL MORPHOLOGY OF BIOMPHALARIA PFEIFFERI (KRAUSS, 1848) AND HELISOMA DURYI (WETHERBY, 1879) FROM MOSHI, TANZANIA, ANALYSED BY MORPHOMETRIC STUDIES

Helisoma duryi, a planorbid snail species, which is a potentialbiological control agent of the intermediate hosts of schistosomiasis,was introduced in an irrigation scheme (T.P.C.) in northernTanzania in 1972. The species has been present at T.P.C. since,and during a snail survey in January 1981, a great variationin the shell morphology of H. duryi, ranging from typical H.duryi forms to forms resembling Biomphalaria pfeifferi, theintermediate host of Schistosoma mansoni in the area, was observed.The Biomphalaria- Wkc forms of H. duryi could constitute anentire population but also occasionally occurred in populationsof typical H. duryi. This study was undertaken to determine whether simple shellmeasurements, or ratios between some of these could be usefulin discriminating between H. duryi and B. pfeifferi. Followingparameters were considered: shell height, shell diameter, diameterof the umbilicus, ratio between shell height and diameter ofthe umbilicus, and the number of whorls. (Received 29 July 1983;     

Effect of Selection for Dark Respiration Rate of Mature Leaves on Crop Yields of Lolium perenne cv. S23

Growth and nutritive quality of two polycross progeny (GL 83and GL 112) from F₁ plants of Lolium perenne ex cv. S23 showingslow dark respiration rates of mature leaves were compared inthe field with S23 in 3 years. Plots were cut either nine (simulatedgrazing) or five (conservation) times annually. In the firsttrial, sown in 1977, dry matter yields from plots of GL 83 werecompared with S23 during 1978 and 1979. A similar trial sownin 1979 compared GL 83, S23 and GL 112 during 1980. The slowrespiration populations displayed consistently greater (6–13per cent) annual dry matter yields than S23, mostly during midto late summer. In the first trial the difference in yield wasgreater in 1979 than 1978 and more under conservation than simulatedgrazing. In the second trial GL 83 and GL 112 yielded 11 and13 per cent more dry matter than S23 under simulated grazingand 5–6 per cent under conservation. There were no consistentdifferences in dry matter digestibility, water soluble carbohydratesor protein between the populations. Cellulose content of GL83 and to a much lesser extent GL 112, tended to be greaterthan that of S23 from July to September. Analysis of one harvestfrom another trial revealed no significant difference in energyvalue, as measured by adiabatic bomb calorimetry, between GL83 and S23. Thus, it appears that the greater dry matter productionof the progeny with slower mature leaf dark respiration ratesreflected a true increase in total energy yield not apparentlyassociated with any agronomically undesirable characteristics.The general significance of the results for crop improvementare discussed. Lolium perenne L., perennial ryegrass, yield of dry matter, energy value, dry matter digestibility     

THE SYSTEMATIC POSITION OF LAROCHEA FINLAY, 1927, AND INTRODUCTION OF A NEW GENUS AND TWO NEW SPECIES (GASTROPODA: SCISSURELLIDAE)

Species of the gastropod genus Larochea Finlay, 1927 are shownto be scissurellids without an anal shell slit or foramen. TheNew Zealand species, L. miranda Finlay, 1927 and L. secundaPowell, 1937, brood their young in the right subpallial cavityagainst a modified inner lip that is set well behind the aperturalplane. Larochea scitula n.sp. is based on shells from WanganellaBank, southern Norfolk Ridge. Larocheopsis n. gen. is introducedfor a minute species from off northern New Zealand that lacksa shell brood chamber. Larochea miranda and Larocheopsis amplexan.sp. are either gonochoristic with smaller males or consecutivehermaphrodites, while Larochea secunda and L. scitula are evidentlygonochoristic, having mature males and females of similar size. (Received 23 July 1992; accepted 10 December 1992)     

GRAZING IMPACT OF,AND INDIRECT INTERACTIONS BETWEEN MESOGRAZERS ASSOCIATED WITH KELP (LAMINARIA DIGITATA)1

Little is known about the indirect effects of nonlethal grazing impacts in mesograzer–seaweed interactions. Using laboratory experiments, the effect of grazing by the seasonally abundant kelp‐associated gastropod Lacuna vincta on subsequent kelp consumption by one kelp‐associated (Idotea granulosa) and one nonassociated species of isopod (I. emarginata) was determined. Measurements of the toughness and elemental composition of different parts of the sporophyte of Laminaria digitata (Huds.) J. V. Lamour., as well as grazer‐induced changes in the palatability of the blade, were conducted to explore possible mechanisms of indirect effects. In situ grazing pressure was the highest between July and September, with the blade being the preferred part of the kelp sporophyte, despite missing differences in the elemental composition among kelp parts. The laboratory experiments supported our hypotheses in that kelp consumption by both species of isopods was lower on intact than on L. vincta–damaged areas of the blade. This pattern was not caused by grazing‐induced changes in blade palatability. Instead, the observed increase in isopod consumption following grazing by L. vincta resulted more likely from the combined effects of a reduction in the toughness of L. vincta–damaged kelp blades and some unknown gastropod cue(s). These results suggest that kelp‐associated and nonassociated mesograzers may benefit from the nonlethal grazing impact of L. vincta due to changes in physical traits of the seaweed. Thus, the nonlethal grazing impact by one species of mesograzer can positively modify the trophic interactions between kelp and other potential competitors, suggesting that the interactions among mesograzers might be more complex than previously assumed.     

Darkness-induced factor affecting basidiocarp maturation in Coprinus macrorhizus

Graftings were made between young basidiocarps of Coprinus macrorhizusgrown under different light programs. Results showed that adiffusible factor(s) affecting basidiocarp maturation was inducedby the darkness of phase 3. (Received July 3, 1979; )     

东灵山地区地表甲虫群落组成及季节变化

本文研究东灵山地区地表甲虫群落的物种组成和季节变化,取样选择在11种不同生境类型内,分别代表该地区的植被类型与环境变化。1999～2000年的野外取样共获得甲虫标本10874号,其中步甲、隐翅虫、叶甲、象甲、拟步甲、金龟和叩甲等7科的个体数量较多,合计占个体总数的83.36%,为该地区地表甲虫的优势类群。选择40个最常见物种统计种类和数量,对生境进行主成分分析排序（PCA）和系统聚类分析,可以将东灵山地区的11种生境类型划归为3类：即梨园岭退耕区的灌丛类型、小龙门林区的森林类型和东灵山主峰区的亚高山植被类型,梨园岭退耕区的辽东栎萌生丛被合并到小龙门林区森林植被类型中,反映了植被类型、海拔高度及受干扰程度可能是决定该地区地表甲虫群落组成和分布的主要因素。研究地表甲虫的季节变化发现其活动高峰多出现在6月和7月,而且在不同生境类型内,优势类群的组成和季节变化有很大差异;小龙门林区内数量分布高于梨园岭退耕区内的分布,尤其在落叶松林和阔叶混交林内的数量优势更加明显。如果按营养层次划分功能群,捕食性类群比例最高,植食性类群次之,腐食性类群最少,捕食性类群的季节活动曲线滞后于植食性类群的活动曲线。     

DISTRIBUTION AND ABUNDANCE OF GYMNOSOMATA (GASTROPODA: OPISTHOBRANCHIA) IN THE SOUTHWEST ATLANTIC

The distribution and abundance of gymnosome gastropods in theArgentine Sea and Brazil—Malvinas Confluence during 1978–1979and 1988 were studied. The collections analyzed included 768quantitative samples obtained between 48°W and the coast,and from 35°S to 55°S. Two species were found. Spongiobranchaeaaustralis was the most frequent and abundant (up to 730 per1000 m3); its presence in the area was associated with the coreof the Malvinas Current. Clione antarctica was less abundant(maximum abundance: 230 per 1000 m³) and was also associatedwith the Malvinas Current. The geographic ranges of both speciesin the area are wider than previously described. Since the rangeof S. australis in the area extends far from the range of itsprey Clio, it is not clear whether S. australis can feed onthe thecosomatous pteropod Limacina (and not only on Clio, asdescribed in the bibliography) or it starves in that area. Duringthe 1978–1979 annual cycle, the abundance of both speciesfollowed neither the abundance patterns of their prey nor ofthe total zooplankton, and differed from each other. The residencetime of swarms of both gymnosomes were shorter than one month.As a general pattern, the aggregates are rapidly transportednorthward by the Malvinas Current and also penetrate the outershelf water, but they remain there only during a short periodand cannot preclude the final expatriation. So, the abundanceof gymnosomes in the area depends on passive migration morethan intrinsic population factors. (Received 9 July 1997; accepted 15 December 1997)     

COMPARISONS OF LIFE-HISTORY TRAITS AND SEXUAL DIMORPHISM BETWEEN ASSIMINEA JAPONICA AND ANGUSTASSIMINEA CASTANEA (GASTROPODA: ASSIMINEIDAE)

Life histories of two sympatric assimineid gastropods, Assimineajaponica and Angustassiminea castanea, were investigated ata reed marsh in northern Japan. Size frequency distributionsrevealed that growth curves of females and males differed inboth species resulting in sexual dimorphisms in shell size.In A. japonica, the shell height of females was larger thanthat of males, whereas in A. castanea males attained a biggershell than females. Mating behaviour of A. japonica was observedmainly from February to June, while that of A. castanea wasobserved from May to August. The diameter of deposited eggsof A. japonica was 200 to 250 mm, whereas that of A. castaneawas 125 to 150 mm. The length of the veliger larva of A. japonicaat hatching was approximately 200 mm, whereas that of A. castaneawas approximately 125 mm. Longevity, age at sexual maturityand opportunities for reproduction during life time were estimatedin the field. For A. japonica, sexual maturity was establishedby the age of 17 months and longevity was about three years.Opportunities for reproduction of A. japonica occurred twiceduring a lifetime. For A. castanea, sexual maturity was establishedby the age of 10 months and longevity was almost five years.Opportunities for reproduction of A. castanea occurred fivetimes during a lifetime. The differences of life-history traitsand sexual dimorphism between species and possible explanationsof evolutionary factors are discussed. To whom correspondence should be addressed. (Received 21 January 1999; accepted 8 September 1999)     

Detecting shape differences in species of the Littorina saxatilis complex by morphometric analysis

We investigated variation in shell size and shape of marinesnail species of the Littorina saxatilis complex (L. saxatilis,L. compressa and L. arcana) using geometric morphometric methods.These morphologically similar periwinkle species that are commonin the European intertidal have presented many problems fordiagnosis based on morphology alone. A discriminant analysisdemonstrated that geometric morphometrics is very efficientfor diagnosing individuals to species among sympatric populations.We successfully diagnosed an average of 96% of the specimens(with 85.7–100% correct diagnosis for specific comparisons).The diagnosis capability of this method is absolute at the populationlevel. This makes the technique potentially useful for the designof manipulative field or laboratory experiments. Moreover, ageometric-morphometric analysis was also accomplished in twosnail ecotypes (H and M) of L. saxatilis from rocky shores ofNE England which are apparently adapted to different degreesof wave exposure. We found that the H (exposed) ecotype hasa relatively rounded shell shape with a bigger aperture, whereasthe M (protected) ecotype has a smaller aperture. (Received 23 March 2006; accepted 25 January 2007)     

Marine cladocerans in Toyama Bay, southern Japan Sea: seasonal occurrence and day-night vertical distributions

Marine cladocerans in the zooplankton samples collected vertically(0–500 m) with Norpac nets at 2–4 week intervalsfrom February 1990 through January 1991 at a station in ToyamaBay, southern Japan Sea, were examined. From mid-March throughearly December, cladoceran populations exhibited five distinctpeaks. in which seven species occurred and showed a species-specific pattern of seasonal distribution. In mid-July. Peniliaavirostris exhibited a prominent peak in population density.Three species of Evadne, E.nordmanni, E.spinifera and E.tergestina,showed a clear ecological separation in time. The first twospecies had a peak density in April and July. respectively,but the last species demonstrated three distinct peaks betweenJune and September. Two congeneric species of the genus Podon,P.leuckarti and P.schmackeri, also did not co-exist in time.Simultaneous horizontal hauls with MTD nets made in June andSeptember 1986 revealed a strikingly marked surface distributionof all species. Evadne nordmanni occurred in June and demonstrateda clear ‘reverse’ did vertical migration, residingin the 30 m depth during the night time and ascending up tothe uppermost water column of 0–10 m during the daytime.Among the four species which occurred in September, E.spinifera,E.tergestina and P.schmackeri also showed a reverse migrationbetween the 30 m depth during the night and the very surfaceduring the day. A different pattern was observed in P.avirostrzs,which was distributed at a depth of 30 m during both the dayand the night with no sign of diel vertical migration. Amongthe more prevalent parthenogenetic individuals, some gamogeneticforms were found to exist in most species occurring in ToyamaBay.     

IN VITRO RECALCIFICATION OF ORGANIC MATRIX OF SCALLOP SHELL AND SERPULID TUBES

Organic matrix was isolated from the shell of the bivalve Argopectenirradians by decalcification. The capacity of the matrix toinitiate formation of crystals similar in form and orientationto the crystals of normal shell was investigated. Decalcifiedshell matrix placed in an inorganic recalcification solutioninitiated the formation of elongate crystals in parallel arrangementcorresponding to the parallel orientation observed in the matrixfibers and similar to the orientation of the long crystals innormal shell. The detailed form of the crystals deposited invitro was different from that of the normal shell crystals.Electron diffraction analysis of remineralized matrix demonstratedthat the material was calcite, the mineral of normal shell. In contrast, the calcareous tube of the serpulid Hydroides dianthushas crystals lacking uniform arrangement and a matrix whichdoes not have a well-oriented structure. The decalcified tubematrix was recalcified and the mineral posited showed some evidenceof normal orientation. The results demonstrate that matrices of Argopecten shell andHydroides tube can induce crystal formation in vitro. Sincethe soluble matrix would be expected to be removed during decalcification,the observed in vitro effects apparently involve the insolublematrix. (Received 19 June 1984;     

CONVERGENT SHELL MORPHOLOGY IN INTERTIDAL GASTROPODS

The functional morphology of shell infrastructure in 2 speciesof intertidal trochid was compared with that in 2 species ofnerite. The shell of Monodonta constrictais typical of the majorityof trochids. The shell is composed of 4 layers: a distal layer(calcite), anouter prismatic layer (aragonite), a nacreous layer(aragonite), and an oblique prismatic layer (aragonite). Monodontalabio lacks a distal layer and an oblique prismatic layer. Theoblique prismatic layer is replaced by an inner prismatic layerwhich forms an apertural ridge as a result of deposition andresorption. The shells of Nerita versicolor and N. tessellataconsistof 3 layers: an outer prismatic layer (calcite), a crossedlamellar layer (aragonite), and a complex crossed lamellar layer(aragonite). The complex crossed lamellar layer is covered withinclined platelets which superficially resemble the surfaceof the ique prismatic layer of trochids. In addition, the complexcrossed lamellar layer forms an apertural ridge which is similarin appearance to that of Monodonta labio. The outer surfaceof the mantle of Nerita versicolor and N. tessellata is throwninto a series of large folds which lie in contact with the inclinedplatelets of the omplex crossed lamellar layer. The interactionof the mantle folds with the inclined platelets is thought toserve as a rachet mechanism to aid in extension of themantle;a similar function has previously been proposed for trochids.The apertural ridges of Monodonta labio and Nerita are thoughtto prevent excessive desiccation when these gastropodsare exposedat low tide. ¹Contribution No. 56 of the Tallahassee, Sopchoppy & GulfCoast Marine Biological Association (Received 6 July 1979;     

Hormonal regulation of genetic tumor induction: Cytokinin and abscisic acid

Young seedlings of the tumor-prone amphiploid Nicotiana suaveolens? N. langsdorjfii were grown aseptically on nutrient mediumin a controlled environment chamber. At regular intervals theincidence of tumor formation was scored and plants were harvested.Total cytokinin activity was determined by means of the cucumbercotyledon bioassay, while ABA activity was measured by radioimmunoassay.A close correlation between onset of tumor formation and elevationin endogenous cytokinin activity was demonstrated, but no correlationwas observed between onset of tumorigenesis and change in thelevel of ABA. In addition, exposure of plants to exogenous ABAdid not alter therate of tumor formation. These results arediscussed in relation to the trigger mechanism for tumor inductionin the Nicotiana system. ¹A preliminary report of some of this work was presented atthe American Society of Plant Physiologists meeting in June1978. ³Present address: Department of Biology, West Virginia University,Morgantown, West Virginia 26506, U.S.A. (Received March 10, 1979; )