DISTRIBUTION AND PRODUCTION OF THREE HYDROBIA SPECIES (GASTROPODA: HYDROBIIDAE) IN A SHALLOW COASTAL LAGOON IN THE BAY OF CADIZ, SPAIN

The abundance, life span, growth and production of the mud snailsHydrobia minoricensis, H. ulvae and H. ventrosa in a semi-naturallagoon system were studied by taking monthly samples at threesites during 1991 and 1992. The most abundant species, H. minoricensisoccurred at mean densities of 12834 to 26264 snails m^–2(10.7 to 25.8g dry weigh m^–2), depending on the site.The least abundant species, H. ulvae, occurred at mean densitiesof 185 to 353 snails m^–2 (3.2 to 2.2g dry weight m^–2).The numerical abundance and biomass of the three Hydrobia specieswere positively related to the biomass of benthic macroalgae(P<0.01). Although H. ulvae egg capsules were recorded throughoutthe year, newly hatched snailsof this species were not observed,in contrast to the other two species. The early spring and summercohorts of H. minoricensis and H. ventrosa seemed to be themost numerous. The average life spans of these two species wereestimated to be about 18 and 13 months respectively. Annualproduction estimates for the whole lagoon system were 29.0 (6.3),5.5 (0.8) and 5.2 (1.0)g dry weight (ash-free dry weight) m^–2yr^–1 for H. minoricensis, H. ulvae and H. ventrosa respectively.The annual P/B ratio was about 2 for H. minoricensis and H.ventrosa. (Received 5 July 1994; accepted 5 October 1994)     

Phylogeography of the Wabash pigtoe, Fusconaia flava (Rafinesque, 1820) (Bivalvia: Unionidae)

Reconstructing the phylogeographic patterns of widely distributedand common freshwater mussel species (Bivalvia: Unionidae) mayprovide insight into unionid evolution and speciation. The Wabashpigtoe, Fusconaia flava, is currently recognized as a single,polytypic species that is widely distributed and common throughoutthe Mississippi River drainage and parts of the Canadian Interior,Great Lakes and Gulf Coast drainages. Sequence analysis of themitochondrial COI gene revealed two divergent (3.43%) clades.Clade A consisted of specimens located throughout the upperand lower Mississippi River drainage and in the Red River (Canada)and Lake Erie drainages and all F. cerina specimens. All haplotypeswithin clade A differed by three (0.55%) or fewer nucleotidesubstitutions from the most widely distributed and abundanthaplotype, F1. Clade B, consisting of specimens located in thefar western portion of the species' range, may comprise an undescribedspecies. There was no evidence of genetic differentiation amongF. flava inhabiting headwater and intermediate-sized river localitiesof the Muskingum River system and large river localities ofthe nearby Ohio River. The divergence among F. flava haplotypescomprising clade A (0.18–1.10%) was similar to the divergencebetween the F. cerina haplotypes and the F. flava haplotypescomprising clade A (0–1.10%). This study illustrates theimportance of accessing genetic diversity across the distributionof a polytypic species. Additional analyses based on a combinationof morphology and genetics are needed to determine the taxonomicstatus of clade B and to strengthen our understanding of therelationship between F. flava and F. cerina. (Received 28 May 2007; accepted 13 August 2007)     

Atebbania Bernasconii, a New Genus and Species from Subterranean Waters of the Tiznit Plain, Southern Morocco (Gastropoda: Hydrobiidae)

The new genus Atebbania is described for a new hydrobiid species,A. bernasconii, which lives in groundwaters of southern Morocco.Of the Hydrobiidae genera with known shell and anatomy Moitessieriais the closest to Atebbania. The two share the following characters:shell elongate; teleoconch surface with evident microsculpture;seminal receptacle absent. Atebbania is distinguished from Moitessieriaby: shell ovate; penis with a) apical stylet, b) one lobe bentdownward on left (inner) side and c) penial duct running nearthe right (outer) side; posterior end of foot indented. Atebbaniabernasconii n. sp., lives in a limited area, the Tiznit plainin southern Morocco. Other stygobiont hydrobiids from otherareas of Morocco are currently being studied. None of them appearsto be closely related to A. bernasconii or to the species ofMoitessieria (Received 10 February 1998; accepted 30 April 1998)     

A NEW, STYGOBIONT, VALVATIFORM, HYDROBIID GASTROPOD FROM AUSTRIA (CAENOGASTROPODA: HYDROBIIDAE)

A new, stygobiont species of Hauffenia (Pollonera, 1898) fromnortheastern Austria is described. It has been previously misidentifiedas H. kerschneri (Zimmermann, 1930), but detailed anatomicalinvestigations indicate that it is a separate species. Distinguishingcharacters are the very reduced peg of the operculum, a hypobranchialgland, an anterior lobe of the digestive gland in 25% of thespecimens, and an upright penial stylet. Some animals were infestedwith sporocysts and rediae. (Received 13 September 1991; accepted 1 November 1991)     

Photosynthesis in Panicum milioides, a Species with Reduced Photorespiration

The capacity for C₄ photosynthesis in Panicum milioides, a specieshaving reduced levels of photorespiration, was investigatedby examining the activity of certain key enzymes of the C₄ pathwayand by pulse-chase experiments with ¹⁴CO₂. The ATP$P₁ dependentactivity of pyruvate,P₁ dikinase in the species was extremelylow (0.14–0.18 µmol mg chlorophyll^–1 min^–1).Low activity of the enzyme was also found in Panicum decipiensand Panicum hians (related species with reduced photorespiration)and in Panicum laxum (a C₃ species). The antibody to pyruvate,P₁dikinase caused about 70% inhibition of the ATP$P₁ dependentactivity of the enzyme in P. milioides. The activity of NAD-malicenzyme and NADP-malic enzyme in ^P. ^milioides was equally low(approximately 0.1–0.2 µmol mg chlorophyll^–1min^–1) and similar to the activity in P. decipiens, P.hians and P. laxum. Photosynthetic pulse-chase experiments underatmospheric conditions showed a typical C₃-like pattern of carbonassimilation including the labelling of glycine and serine asexpected during photorespiration. During the pulse with ¹⁴CO₂only about 1% of the labelled products appeared in malate and2–3% in aspartate. During a chase in atmospheric levelsof CO₂ for up to 6 min there was a slight increase in labellingin the C₄ acids. The amount of label in carbon 4 of aspartatedid not change during the chase, indicating little or no turnoverof the C₄ acid via decarboxylation. The results indicate thatunder atmospheric conditions P. milioides assimilates carbondirectly through the C₃ pathway. Photorespiration as indicatedby the CO₂ compensation point may be repressed in the speciesby a more efficient recycling of photorespired CO₂. (Received June 8, 1982; Accepted July 22, 1982)     

Molecular evolution of ribulose-1, 5-bisphosphate carboxylase

The structural homology of the two constituent subunits (A andB) of ribulose- 1,5-bisphosphate carboxylase from various originswas determined using the statistical method of Marchalonis andWeltman [Comp. Biochem. Biophys. 38B, 609–625 (1971)].It was found that the large catalytic subunit (A) is structurallyhomologous among the enzymes of divergent origins, from primitivephotosynthetic bacteria (Bacteriophyta) through the green algae(Chlorophyta) to higher plants (Tracheophyta). In contrast,the small regulatory subunit (B) was found to be structurallyquite different among the different species. The genetic conservationof subunit A during the phylogenetic evolution of the ribulose-1,5-bisphosphatecarboxylase molecule indicates its origin from a common ancestralgene. ¹ This is paper XXXIII in the series "Structure and Functionof Chloroplast Proteins". (Received July 23, 1975; )     

A holistic approach to taxonomic evaluation of two closely related endangered freshwater mussel species, the oyster mussel Epioblasma capsaeformis and tan riffleshell Epioblasma florentina walkeri (Bivalvia: Unionidae)

Species in the genus Epioblasma have specialized life historyrequirements and represent the most endangered genus of freshwatermussels (Unionidae) in the world. A genetic characterizationof extant populations of the oyster mussel E. capsaeformis andtan riffleshell E. florentina walkeri sensu late was conductedto assess taxonomic validity and to resolve conservation issuesfor recovery planning. These mussel species exhibit pronouncedphenotypic variation, but were difficult to characterize phylogeneticallyusing DNA sequences. Monophyletic lineages, congruent with phenotypicvariation among species, were obtained only after extensiveanalysis of combined mitochondrial (1396 bp of 16S, cytochrome-b,and ND1) and nuclear (515 bp of ITS-1) DNA sequences. Incontrast, analysis of variation at 10 hypervariable DNA microsatelliteloci showed moderately to highly diverged populations basedon F_ST and R_ST values, which ranged from 0.12 to 0.39 and 0.15to 0.71, respectively. Quantitative variation between specieswas observed in fish-host specificity, with transformation successof glochidia of E. capsaeformis significantly greater (P<0.05)on greenside darter Etheostoma blennioides, and that of E. f.walkeri significantly greater (P<0.05) on fantail darterEtheostoma flabellare. Lengths of glochidia differed significantly(P<0.001) among species and populations, with mean sizesranging from 241 to 272 µm. The texture and colourof the mantle-pad of E. capsaeformis sensu stricto is smoothand bluish-white, whereas that of E. f. walkeri is pustuledand brown, with tan mottling. Based on extensive molecular,morphological and life history data, the population of E. capsaeformisfrom the Duck River, Tennessee, USA is proposed as a separatespecies, and the population of E. f. walkeri from Indian Creek,upper Clinch River, Virginia, USA is proposed as a distinctsubspecies. (Received 23 February 2005; accepted 16 January 2006)     

Regional, vertical and seasonal distribution of phytoplankton and photosynthetic pigments in Lake Baikal

A 3-year phytoplankton study was carried out in Lake Baikal(Siberia) as part of the CONTINENT project and in conjunctionwith a 60-year long monitoring programme by the Irkutsk StateUniversity. A combination of microscopy and high performanceliquid chromatography (HPLC) pigment analysis was used. Allover the lake, the dominant functional group (by biovolume)was the vernal diatom blooms, due to the dominance of endemicCyclotella species. Chlorophyll a (Chl a) was significantlyhighest at the Selenga and Barguzin inflows (2.39 ± 0.34and 2.49 ± 0.18 nmol L^–1, mean ± 95% CI,respectively) and higher in the South than in the North (1.43± 0.26 and 0.96 ± 0.13 nmol L^–1). This variationof Chl a reflected changes in the phytoplankton composition.Diatoms and Chrysophyceae were the major contributors to thetotal Chl a except in the South (Chlorophyceae) and SelengaDelta (cyanobacterial picoplankton). There were also indicationsof species composition changes due to enhanced P-loading fromthe Selenga River. However, canonical analyses indicated thattemperature and stratification were the major driving forcesfor regional distribution patterns and seasonal succession.It seems likely that further global warming will cause a shiftin the species and group composition towards small cells atthe expense of the large endemic diatom flora.     

A Comparison of the Growth, Photosynthesis, Stomatal Conductance and Water Use Efficiency of Moricandia and Brassica Species

When grown in pots and well-watered, the relative growth ratesof the above ground parts of two species of Moricandia (M. arvensis,an intermediate C₃–C₄ species, and M. moricandioides,a C₃ species) were inferior to those of two cultivated Brassicaspecies (B. campestris and B. napus). The Moricandia specieshad thicker leaves (greater d.wt per unit leaf area) with morechlorophyll than the Brassica species and had slightly greaterrates of photosynthesis per unit leaf area at an irradiance(400–700 nm) of 2000 µmol quanta m^–2 s ^–1.Leaves of M. arvensis, known to have a CO₂ compensation pointbetween that of C₃ and C₄ species, had a lower ratio of theintercellular to atmospheric partial pressure of CO₂ (C₁/C_a)and a greater instantaneous water use efficiency (WUE) thanthose of M. moricandioides and the Brassica species. Carbon isotope discrimination (     

Reproduction rates and secondary production of three species of the rotifer genus Synchaeta in the estuarine Potomac River

Rotifers are a relatively well-studied component of lacustrinesystems but their role is only poorly understood in estuaries.Three species of the genus Synchaeta—S. baltica, S. triophthalmaand S.cecilia—dominate the cold-water assemblage of rotifersin Chesapeake Bay. Laboratory experiments were conducted todetermine the temperature dependence of egg development time(EDT) for each species; EDT varied over an approximate rangeof 90–9 h as temperature (T) varied from 2 to 22°C.The EDT/temperature relationships could be closely fitted bya simple polynomial equation of the form log(EDT) = a + b(logT) + c(log T)² for each species. Natural populations of thesethree rotifers were sampled during a cruise in the Potomac River(7–11 March 1983). Estimates of specific reproductiverates (b) were calculated based on the previously defined EDT/temperaturerelationship and the observed ratio of eggs/rotifers for eachspecies. The two most abundant species, S.triophthalma and S.cecilia,showed a clear dependence of b on the observed chlorophyll aconcentrations. Maximum reproductive rates ({small tilde}0.015h^–1) were attained only at relatively high phytoplanktondensities within a bloom of Heterocapsa triquetra where thechlorophyll a concentrations exceeded 10 µg l^–1.Estimates of secondary production suggest that Synchaeta spp.may contribute to the trophic flow of carbon in this systemwith a significance at least similar to that of the planktoniccopepods.     

Promotion of Cocklebur Seed Germination by Allyl, Sulfur and Cyanogenic Compounds

The effects of allyl, sulfur and cyanogenic compounds on thegermination of upper cocklebur (Xanthium pennsylvanicum Wallr.)seeds were examined. Mercaptoethanol and methylmercaptan aswell as KCN, substrates for rßcyanoalanine synthase(CAS), and H₂S and thiocyanate, the products of the CAS catalyzingreaction, were effective in promoting germination, suggestingthe involvement of CAS in germination. Most of allyl compounds, especially allylthiourea, as well asethylene which activated CAS [Hasegawa et al. (1994) Physiol.Plant. 91: 141], promoted the germination in an abnormal typewhich occurred by the predominant growth of cotyledons as didC₂H₄ [Katoh and Esashi (1975) Plant Cell Physiol. 16: 687].However, they failed to activate CAS unlike ethylene, and toliberate free ethylene during an incubation period. It was thuspossible that an C₂H₄-like double bond within allyl compoundscan act to promote seed germination. (Received June 10, 1996; Accepted August 21, 1996)     

Identification, distribution and relative abundance of paralarval gonatid squids (Cephalopoda: Oegopsida: Gonatidae) from the Gulf of Alaska, 2001 2003

Paralarvae of the family Gonatidae were sampled in the Gulfof Alaska during spring 2001–2003. Taxonomic characterswere determined to allow identification of the specimens tospecies. The dorsal head chromatophore pattern (DHCP) was themost robust character and allowed identification to speciesfor the first time without requiring the removal and examinationof the radula. Six different DHCPs were found among the sixspecies in the study area. The 1140 specimens collected consistedof the following six species: Berryteuthis anonychus (759),Berryteuthis magister (71), Gonatopsis borealis (155), Gonatuskamtschaticus (1), Gonatus madokai (4) and Gonatus onyx (143).The specimens had a size range of 3.0–20.63 mm dorsalmantle length with the majority of specimens smaller than 10 mm.All species showed an increasing trend in abundance from theshelf (0–200 m) to the slope (200–1000 m)to the basin (>1000 m) except G. onyx in 2001 and 2002.Wide variation in distribution and abundance was found for thefour most abundant species; however, in general, B. anonychuswas most abundant and widely distributed, followed by Gonatopisborealis, Gonatus onyx and B. magister. (Received 28 April 2006; accepted 1 February 2007)     

The rotifers of Warri River, Nigeria

The rotifer assemblage of the dendritic tidal Warri River wasinvestigated at four sampling points from July 1981 to July1982. Forty-one species of Rotifera were identified. Five ofthese — Anuraeopsis racenesi Berzins Keratella cochlearismacracantha Lauterbom, Monostyla lunaris Pawlowsky,M. stenroosiMeissner and Trichocerca similis grandis Hauer — are beingrecorded for the first time in West Africa. The Warri Riverrotifers are 65% cosmopolitan and 20% pantropical although therewas no species limited to African waters only. The dominantrotifers in the Warri River were Keratella tropica and K. cochleariswhich were found in the predominantly freshwater sampling stationat Udu Bridge to Warri and Orugbo Creek where low brackish watersalinities and conductivities are observed from December orJanuary to April each year. The preponderance and longitudinaldistribution of these two well-known cyclomorphic rotifers providesan opportunity to study their salinity tolerance and the effectof salinity and conductivity on their cyclomorphosis by samplingalong the length of the river from Udu Bridge to Forcados wherethe Warri River joins the Atlantic Ocean.     

Photosynthetic Characteristics of C3-C4 Intermediate Flaveria Species II. Kinetic Properties of Phosphoenolpyruvate Carboxylase from C3, C4 and C3-C4 Intermediate Species

The kinetic properties of phosphoenolpyruvate (PEP) carboxylasehave been studied among several Flaveria species: the C₃ speciesF. cronquistii, the C₃–C₄ species F. pubescens and F.linearis, and the C₄ species F. trinervia. At either pH 7 or8, the maximum activities (in µmol.mg Chl^–1.h^–1)for F. pubescens and linearis (187–513) were intermediateto those of the C₃ species (12–19) and the C₄ species(2,182–2,627). The response curves of velocity versusPEP concentration were hyperbolic for the C₃ and C₃–C₄species at either pH 7 or 8 while they were sigmoidal for theC₄ species at pH 7 and hyperbolic at pH 8. The K_m values forPEP determined from reciprocal plots were lowest in the C₃ species,and of intermediate value in the C₃–C₄ species comparedto the K' values of the C₄ species determined from Hill plotsat either pH 7 or 8. Glucose-6-phosphate (G6P) decreased theK_m values for PEP at both pH 7 and 8 in the C₃ and C₃–C₄species. In the C₄ species, G6P decreased the K' values at pH8 but increased the K' values at pH 7. In all cases, G6P hadits effect by influencing the activity at limiting PEP concentrationswith little or no effect on the maximum activity. At pH 8 andlimiting concentrations of PEP the degree of stimulation ofthe activity by G6P was greatest in the C₄ species, intermediatein F. linearis, a C₃–C₄ species, and lowest in the C₃species. In several respects, the PEP carboxylases of the C₃–C₄Flaveria species have properties intermediate to those of theC₃ and C₄ species. (Received April 30, 1983; Accepted August 22, 1983)     

Temperature-dependent development in marine copepods: comments on choices of models

Guerrero et al (1994) promote Tauti's equation, rate = a exp(b temp), as simple to fit by log conversion (which may be formallyinappropriate), empirically adequate, and having ‘appropriatebiological characteristics’. No function is justifiablefrom reductionist theories, but Belehrádek's, rate =a (temp – T₀)^b, with b fixed for the taxon of interest,fits equally well, and singularly distinguishes differencesattributable to temperature adaptation (T₀, often misunderstoodas ‘biological zero’), and to size or other species-dependentproperties (a).     

Effect of Sodium on Phosphate Uptake in Unicellular and Filamentous Cyanobacteria

The effect of Na⁺ on phosphate uptake was studied in four strainsof cyanobacteria: Synechococcus PCC 7942, Gloeothece PCC 6501,Phormidium sp. and Chlorogloeopsis PCC 6912. Phosphate uptakewas stimulated by Na⁺ in all cases. Li⁺ and K⁺ acted as partialanalogues for Na⁺. Half-saturation [K_1/2(Na⁺)] of phosphateuptake was reached with Na⁺ concentrations ranging from 317µM in Chlorogloeopsis to 659 µM in Phormidium. Theconcentration of phosphate required to reach half-saturationof phosphate uptake [K_1/2(P_i)]was not changed by the presenceof Na⁺. (Received April 11, 1994; Accepted July 5, 1994)     

Summer coastal zooplankton biomass and copepod community structure near the Italian Terra Nova Base (Terra Nova Bay, Ross Sea, Antarctica)

The structure of the zooplankton biotic community and of copepodpopulation in the coastal area of Terra Nova Bay (Ross Sea,Antarctica) was investigated during the 10th Italian AntarcticExpedition (1994/1995). Zooplankton biotic community consistedmainly of pteropods (Limacina helicina and Clione antarctica),Cyclopoid (Oithona similis), Poecilostomatoid (Oncaea curvata)and Calanoid (Ctenocalanus vanus, Paraeuchaeta antarctica, Metridiagerlachei and Stephos longipes) copepods, ostracods, larvalpolychaetes and larval euphausiids. Zooplankton abundance rangedfrom 48.1 ind m^–3 to 5968.9 ind m^–3, and copepodabundance ranged from 45.2 ind m^–3 to 3965.3 ind m^–3.The highest peak of zooplankton abundance was observed between25 m and the surface and was mainly due to the contributionof O. similis, O. curvata and C. vanus. Zooplankton biomassranged from 5.28 mg m^–3 to 13.04 mg m^–3 dry weight;the maximum value was observed between 25 m and the surface.Total lipid content varied from 216.44 to 460.73 mg g^–1dry weight.     

CORRECTIONS, VOLUME 29

Part 1, under the frontispiece portrait of Dr. N. B. Eales,the words ‘President 1948–1951’ should havebeen added. Page 103, line 49, for ‘Newton Collection’ read‘Norman Collection (Canon Norman)’. 185, line 37, for ‘capillaris’ read ‘capillacca’. 188, Table 1, for ‘bemoralis’. read ‘nemoralis’. 188, Table 2, for ‘Cochlicella acuta (Müll)? ventrosa(Fér.)’ read ‘Cochlicella ventrosa (Fér.)’. 191, line 24, for ‘araheo-’ read ‘archeo-’.     

Long-Term Chilling of Young Tomato Plants under Low Light. IV. Differential Responses of Chlorophyll Fluorescence Quenching Coefficients in Lycopersicon Species of Different Chilling Sensitivity

Temperature dependences of chlorophyll fluorescence quenchingcoefficients were studied in the cultivated tomato (Lycopersiconesculentum) and three lines of the chilling-tolerant L.peruvianumfrom different altitudes, i.e. LA 1373 (20 m a.s.l.), LA 2157(1,650 m a.s.l.) and LA 385 (2,400 m a.s.l.). At actinic lightintensity near light saturation of photosynthesis (370 µEm^–2 s^7minus;1), photochemical quenching (qP) increasedwith increasing temperature between 5 and 30°C. The temperature,at which qP reached the numerical value 0.5 [T (qP=0.5)] decreasedby 2.5–4.5°C after a chilling treatment of 14 daysat 10°C in L. peruvianum, indicating acclimation of thephotosynthetic dark reactions in this species. The final T (qP=0.5)attained after chilling could be arranged in the order L.esculentum>LA1373>LA 2157>LA 385. The fast relaxing non-photochemicalquenching (qN) component (qf, consisting mainly of energy-dependentquenching, qE) exhibited minima near the optimum temperaturefor photosynthesis. These minima shifted to lower temperaturesupon chilling in L. peruvianum. Photoinhibitory quenching (ql)was unaffected by chilling in the high altitude lines, but-increasedstrongly in LA 1373 and L. esculentum. Under low actinic light(40 µE m^–2 s^–1), temperature dependences ofqP and qN were nearly identical in L. esculentum and LA 385and revealed abrupt changes at approx. 8°C. It is concludedthat qP and ql, measured after defined chilling treatments,are valuable screening parameters for chilling tolerance inearly growth stages of Lycopersicon plants. (Received November 2, 1993; Accepted February 28, 1994)     

DENSITY FLUCTUATIONS, GROWTH AND DRY TISSUE PRODUCTION OF HYDROCOCCUS BRAZIERI (TENISON WOODS, 1876) AND ARTHRITICA SEMEN (MENKE, 1843) IN PEEL INLET, WESTERN AUSTRALIA

Hydrococcus brazieri and Arthritica semen on a sandflat at Coodanup,Peel Inlet, Western Australia, accounted for 89.5% of totalmollusc numbers. The mean density of H. brazieri was 9487 m^–2and A. semen averaged 8105 m^–2. H. brazieri grew at 0.5mm month^–1 and reached maturity in 4 months; A. semengrew at 0.3 mm month^–1 and reached maturity in 6 months.Somatic production in the Peel-Harvey estuarine system was estimatedto be 0.5 g m^–2yr^–1for H. brazieri and 4.1 g m^–2yr^–1for A. semen. The positions of these two species in the estuarinefoodweb is discussed. (Received 26 June 1981;