Effects of temperature, salinity and food level on the life history traits of the marine rotifer Synchaera cecilia valentina, n. subsp.

A strain of the marine rotifer Synchaeta cecilia valentina,n. subsp., isolated from the Hondo of Elche Spanish Mediterraneancoastal lagoon at 22 salinity, was cultured in the laboratoryin 20 ml test tubes and fed with the alga Tetrasemis suecica.The effect of two temperatures (20 and 24°C), four salinities(20,25,30 and 37) and two food levels (15 000 and 25000 cellsml^–1) on the life history traits of this rotifer werestudied in life tables performed with replicated individualcultures. Temperature and salinity had a significant negativeeffect (P < 0.001) on the average lifespan (LS) and on thenumber of offspring per female (R₀) The effect of food levelon LS is unclear, whereas R₀ is greater at 20°C with thelower concentration of algae and at 24°C with the higheralgal concentration. The maximum values of LS and R₀, 5.6 daysand 9.2 offspring per female, respectively, were recorded at20°C, 25o salinity and low food concentration. There isalso a clear negative effect on the intrinsic growth rate (r)due to salinity. The effect of temperature depends on the foodlevel and, as occurs with R₀ the maximum values of r occur withthe lower algal concentration at 20°C, whereas at 24°Cthey are obtained with the higher algal concentration. Theser values, from 1.04 to 1.10 day^–1, were reached at 24°C,salinities of 20–25 and with high food concentration.     

Seasonal species composition of barnacle larvae (Cirripedia: Thoracica) in Rhode Island waters, 1977-1978

Cirripede larvae can occur year-round in temperate and tropicalwaters, often in significant numbers, yet the species compositionof the ‘Balanus sp.’ component is rardy studied.Weekly plankton samples were analyzed qualitatively for larvalcirripede species and stage over a year (1977–1978) attwo Rhode Island stations. Six species of larvae were foundin Lower Narragansett Bay (30° salinity). Semibalanus balanoidesand Balanus balanus have a single winter brood. S. balanoidesis the predominant winter breeder with a minor release of naupliiin early December and major release in March followed by cypridsin mid-April.B. balanus populations release all larvae in Marchwith cyprids in mid-April. Balanus crenatus is mainly a winterbreeder, but has multiple broods; it does not breed in July-Septemberwhen the water temperature is above 18°C. Balanus venustusis the predominant summer breeder, and larvae were observedfrom May through December (water >8°C). Larvae of Chthamalusfragilis and Balanus eburneus occur in low numbers from May-October.At the Pettaquamscutt River site (12 salinity), Balanus improvisuslarvae predominate and early stage nauplii (I-II) occur in samplesyear round (0–27°C). Two peaks of later stage naupliiand cyprids occur in late spring (May) and early winter (Nov.-Jan.).Continued temperatures bdow 5°C or above 20°C appearto inhibit larval development. Comparison of results with existing literature reveals severalsignificant findings. The bimodal rdease of S. balanoides larvaeis unusual and may be in response to the phytoplankton dynamicsof the year; however, the existence of distinct races of S.balanoides may also be a factor. Larvae of B. venustus predominatein the lower bay during the summer, yet this species is unreportedin past studies. B. improvisus nauplii are more cold tolerantthan previously reported. Comparison of findings with reportedbreeding patterns in Florida indicate significant differencesin temperature responses between northern and southern populations. ¹Contribution No. 188 from EPA Environmental Research Laboratory,South Ferry Rd., Narragansett, RI 02882     

Temperature and salinity effect on growth and chemical composition of Gyrodinium aureolum Hulburt in culture

A factorial experiment shows highly significant effects of temperature(12 5–22.5°C) and salinity (17.8–34 S) on thegrowth rate of Gyrodinium aureolum, with a significant temperature-salinityinteraction. The maximum growth rate of G aureolum is measuredto 0.61 div. day^–1 at 20°C and 22.3 S. Gyrodiniumaureolum does not grow at temperatures :10 °C or 25°Cand at salinities 12 S. The cellular content of carbon (C) andnitrogen (N) and the elemental ratios N/C, P/C and N/P are significantlyaffected by the temperature The cellular content of phosphorus(P) and the elemental ratios P/C and N/P vary significantlywith salinity Significant temperature-salinity interactionsare found for the cellular content of carbon, nitrogen and phosphorus.Variations in the N/P ratio indicate that G.aureolum has a largestorage capacity for phosphorus It is suggested that temperatureis one important limiting factor in the initiation of bloomsof G.aureolum in north European waters.     

The influence of salinity fluctuation on the ammonium metabolism of the marine diatom Skeletonema costatum grown in continuous culture

Ammonium-limited cultures of Skeletonema costatum were grownat dilution rates from 0.019 to 0.038 h^–1 at an averagesalinity of 22.4 For a few days cultures were exposed to a freshwaterpulse. When salinity was decreased to 8.6 (average minimum)photosynthesis and cell division were inhibited. Both in vivoand DCMU-enhanced fluorescence per cell were statistically constant:photosystems I and II were not inhibited by a gradual salinitydecrease. Ammonium assimilation was affected via an inhibitionof carbon fixation. Ammonium concentrations increased in thecontinuous cultures, whereas the overcapacity of ammonium uptakedeclined: the nitrogen limitation was relieved. When salinitywas increased again, photosynthesis and cell division were stimulated.Salinity fluctuations were accompanied by a fluctuation in thepools of aspartic acid (0.5–1.0 mM), glutamine acid (0.9–4.1mM) and glutamine (0.5–2.0 mM). The pool of glutamic acidfollowed the salinity pattern (r=0.67, P<0.05). The correlationbetween the amino acid pool and the osmotic value of the mediumwas significant (r=0.72, P<0.05). Cellular glutamic acidand glutamine levels increased until the nitrogen limitationwas restored.     

Influence of salinity and temperature on growth and survival of the planktonic larvae of Marenzelleria viridis (Polychaeta, Spionidae)

In a series of experiments, the planktonic larvae of Marenzelleriaviridis (Verrill, 1873) were exposed to various combinationsof salinity (S = 0.6, 2.5, 5.0, 10 and 20) and temperature (T= 5, 10 and 20C) from the 1-setiger stage to the onset of metamorphosis(16- to 17-setiger stage). One-setiger larvae were unable tocomplete their development to metamorphosis at salinities below5. Metamorphosis was successful at salinities of 10 and 20,when the animals adopted a benthic life mode. Larval developmentwas more rapid at 10 than at 20, and was positively affectedby higher temperatures. Larvae exposed to a salinity of 3.5at the 4- to 5-setiger stage developed and completed metamorphosisto benthic juveniles despite the low salinity. These larvaedeveloped most rapidly at a temperature of 10C. The salinitytolerances (LC₅₀) of M. viridis larvae (t = 48 h), juvenilesand adults (t = 72 h in each case) were determined at 10C.The results showed that all development stages can toleratesalmities <1 The importance of constraints on developmentand tolerance to low salinities for the successful colonizationof oligohaline regions is shown and discussed in connectionwith other brackish-water organisms.     

Occurrence of mycosporine-like amino acids in the red-tide dinoflagellate Alexandrium excavatum: UV-photoprotective compounds?

Water extracts of the red-tide dinoflagellate Alexandrium excavatumgrown at ‘high’ light intensity (200 µE m^–2s^–1) show a broad absorbance maximum in the UV regionof the spectrum (310–360 nm). Using TLC and reverse-phaseHPLC a series of mycosporine-like amino acids have been characterized:mycosporine-glycine (_max = 310 nm), palythine (_max = 320 nm),asterina-330 (_max = 330 nm), shinorine (_max = 334 nm), porphyra-334(_max= 334 nm), palythenic acid (_max = 337 nm) and the isomericmixture of usujirene and palythene (_max = 359 nm). From theobserved spectral changes during transference from ‘low’(20 µE m^–2 s^–1) to ‘high’ (200µE m^–2 s^–1) light intensities and vice versa,the series of compounds are supposed to be biogenically relatedto one another. The presence of these compounds in A.excavatumis discussed in relation to their possible role in the photoprotectionto deleterious UV radiation.     

Response of Gonyaulax tamarensis to the presence of a pycnocline in an artificial water column

In nature, large concentrations of the toxic bloom-forming dinoflagellate,Gonyaulax tamarensis, are frequently observed in the vicinityof the pycnocline. In the absence of a pycnocline the organismis usually recorded near the surface, where light levels aremore advantageous for photosynthesis. In this paper we examinethe swimming behaviour of G.tamarensis when exposed to varyingdegrees of stratification and investigate whether the maintenanceof a subsurface (pycnocline) population is the result of retentionof the algae by a physical barrier or active accumulation ofthe organisms at a density interface. The study indicates thatG.tamarensis cells presented with a halocline of S<{smalltilde}6–7 (occurring over a few centimeters) cross thissalinity barrier and accumulate at the highest available photonflux density ({small tilde}100 µmol m^–2 s^–1).Cells exposed to a gradient of S>{small tilde}7remain atthe halocline (pfd={small tilde}40 µmol m^–2 s^–1).However, when light above the pycnocline is attenuated by theaddition of food colour to the medium, the cells cross a haloclineof S=10 and accumulate at the highest available photon fluxdensity. In the absence of added nutrients (inorganic N andP) the organism fails to exhibit a phototactic response. Thus,the presence of a strong halocline does not represent an inpenetrablephysical barrier for G.tamarensis and the development of pycnoclinepopulations of this organism is a function of density, lightand nutrient climate.     

Interspecific variability and environmental influence on particulate organic carbon {delta}13C in cultured marine phytoplankton

The stable carbon isotope composition of particulate organicmatter expressed as ¹³C was measured in cultures of 13 speciesof marine microalgae in different phylogenetic groups. The effectsof salinity variations and changes in photoperiod were alsoassayed for three of them (i.e. Skeletonema costatum, Amphidiniumopercularum and Isochrysis galbana); the effect of nature ofnitrogen supply (nitrate. ammonium) was studied for one (S.costatum).These environmental parameters were chosen because of theirvariability in the ocean and their possible effects on ¹³C valuesof phytoplankton organic carbon. Batch culture conditions andsampling time after inoculum were strongly controlled in orderto provide cells in good physiological state which were comparablefrom one culture to the other. In the same way, sampling waslimited to the first 2 days of exponential growth, in orderto avoid a possible dissolved inorganic carbon (DIC) limitation.Carboxylase activities [of the enzyme ribulose 1,5-bisphosphatecarboxylase oxygenase (Rubisco), and the three ß carboxylases:phosphoenolpyruvate carboxylase (PEPC), phosphoenolpyruvatecarboxykinase (PEPCK) and pyruvate carboxylase (PC)] and totalchlorophyll a concentrations were assayed simultaneously. The¹³C values observed were between –30.2 and –12.7i.e. comparable to those observed in the world's oceans. Theisotopic composition of phytoplankton organic carbon was shownto be under the influence of the parameters tested but ¹³C variationsare specific to the species considered. The nature of ßcarboxylase found in each species, or systematic position, couldnot be linked to the isotopic composition of organic carbon.No linear or single correlation between ¹³C variations and environmentalmodifications were observed and there is no evidence for a simpleand universal relation between ¹³C of phytoplankters and theirenvironment. In monospecific cultures as in the field, ¹³C fractionationby Rubisco (and eventually by PEPCK) may be counterbalancedby other mechanisms.     

Studies on the larval development of northeastern Atlantic and Mediterranean Procellanidae (Decapoda,Anomura). I — Redescription of the larval stages ofPorcellana platycheles (Pennant, 1777) reared under laboratory conditions

The complete larval development is described forPorcellana platycheles (Pennant) reared under laboratory conditions. The development consists of two zoeal stages and one megalopa. At 20°C and 35‰ salinity, the megalopa appeared 17–18 days after hatching. Survival was 56% from hatching to the megalopa stage. The morphological features of the zoeal and megalopa stages ofP. platycheles are compared with those of other species ofPorcellana, and a key of the known zoeal stages of the genus is given.     

Trophic diversity within the planktonic food web of the Elbe Estuary determined on isolated individual species by 13C analysis

The uptake of organic substrates by heterotrophic planktonicorganisms was studied along the freshwater Elbe Estuary in May,July and October 2000 using ¹³C analysis of individually isolateddominant species of copepoda, cladocera, rotifera and ciliata.Non-sedimenting suspended particulate matter (SPM_ns) was separatedfrom sedimenting matter and further analysed for the chemicalcomposition of its different size fractions in order to estimatesubstrate availability. Particles <5 µm accounted for15% of total SPM_ns [40 mg dry weight (DW) L^–1] and containedC:N ratios indicating a predominance of living matter (i.e.mass C:N of phytoplankton). All species under study exhibiteda high capacity for selective feeding with little variationin the diet along the whole freshwater profile. Picoplanktonof 0.2–1.2 µm formed mainly by bacteria had a ¹³Cvalue of –26 in May and July and –29 in October,similar to the ¹³C of the dissolved organic carbon (DOC). Bacteriadid not fractionate isotopically and did not preferentiallyconsume specific subunits of their substrate, i.e. they exhibitedno trophic shift. It appears that phytoplankton exudates werea minor component to total DOC in this estuary. Phytoplanktonwas the exclusive food for all phagotrophic organisms understudy in July, thus only one trophic level was exhibited. DuringMay and October the grazers under study used different substrates,resulting in a planktonic food web of three trophic levels formedby different species of the taxonomic groups under study. Theresults indicate a conditioned behaviour with regard to substrateselection allowing the grazers to produce high abundances evenwhen particles were abundant and competition for phytoplanktonwas high.     

{delta}15N signatures of marine mesozooplankton and seston size fractions in Kiel Fjord, Baltic Sea

The ¹⁵N of marine mesozooplankton species was measured on fouroccasions. Significant differences were found between copepodsand meroplanktonic larvae, yet not between holoplanktonic species.On average, mesozooplankton was enriched by 3.4 ± 0.9relative to selected seston size fractions. Despite suggestingsmall differences (0.5 to 1) in the ¹⁵N of different phytoplanktontaxa on one occasion, the size fractionation procedure generallyproved inadequate in separating major taxonomic groups composingseston. This circumstance, and phase-shifts in the transmissionof rapid changes (>2) in seston ¹⁵N to mesozooplankton complicatethe calculation of mesozooplankton trophic levels.     

DISTRIBUTION AND POPULATION DYNAMICS OF THREE POPULATIONS OF SIPHONARIA ON ROCKY INTERTIDAL SHORES IN HONG KONG

The pulmonate limpets Siphonaria japonica and Siphonana siriusoccur over a wide range of local habitat types in terms of exposureto wave action and salinity. This is a study of these two specieson three different shore types in Hong Kong, ranging from anextremely exposed, high salinity (32–35) shore at Caped'Aguilar to a sheltered, low salinity (16–33) shore atTai Lam Chung. Both species are restricted to the low shore,year round. S. japonica is a winter breeder and recruitmentoccurred between October and January. The recruitment of S.sirius could not be recognised from the size-frequency histograms.The algal standing crop at Tai Lam Chung was higher than atWu Kwai Sha during the winter period, i.e., between Octoberand April. Seasonal fluctuations in growth rate were recordedfor both Siphonaria species with the time of fastest growthoccurring in winter. S. japonica grew faster at Tai Lam Chungthan at Wu Kwai Sha. Food availability is thought to be an importantfactor affecting growth. (Received 17 September 1993; accepted 16 June 1994)     

The Effect of Environmental Factors on Development of the Land-Grab, Cardisoma guanhumi Latreille

Larvae of the land-crab, Cardisoma guanhumi, Latreille. weremaintained in 24 different combinations of salinity and temperaturefrom the time of hatching. Survival to the first crab occurredin salinities of 15–45 p.p.t., 25° and 30°C. Durationof the five zoeal and one megalops stages was similar in salinitiesof 20–40 p.p.t., but at 15 and 45 p.p.t. a greater periodof time was required for total development. Mortality of allthe larvae at 20°C suggests that temperature plays a moreimportant role in survival and distribution of the larvae ofC. guanhumi than salinity. Increments of size in crabs during the first seven post-larvalmolts were similar in salinities of 5–35 p.p.t., 25°C,but in fresh water increase in size at the time of molting wasreduced. Although there was no apparent relationship betweenfrequency of molting and salinities of 5–35 p.p.t., theduration of intermolt was reduced in crabs maintained in freshwater, and survival was also lower. From the present study there is no indication that the morphologicaland physiological processes that are associated with adaptationof the adult crab to the terrestrial environment are initiatedduring larval development. Although the adult crabs have successfullypenetrated the terrestrial environment, the pelagic larvae arestill subject to the numerous ecological variables of the estuarineand marine environments.     

The influence of temperature and light on the upper limit of Microcystis aeruginosa production in a hypertrophic reservoir

Primary production was measured for 7 years, using the in situ¹⁴C-method in hypertrophic Hartbeespoort Dam, South Africa,to examine the influence of light and water temperature on theupper limit of Microcystis aeruginosa production. Water temperaturesvaried from 11 to >25°C and chlorophyll concentrationsreached 6500 mg m^–3. The maximum volumetric rate of production(A_max) was 12->8800 mg C m^–3 h^–1 with areal productions(A) of 69->3300 mg C m^–2 h^–1 for euphotic zonedepths of <0.5–8.4 m. The intrinsic parameters of phytoplanktonproduction (, A_max/B, I_k) indicated that the phytoplankton populationwas adapted to high light levels. Both A_max/B and I_k were correlatedwith temperature. Under optimal conditions, , the theoreticalupper limit of A, was calculated to be 2.8 g Cm^–2 h^–1,while the measured rate was 2.5 g Cm^–2 h^–1. Measuredareal rates exceeding were overestimated due to methodologicalproblems when working with Microcystis scums. Light and watertemperature interacted to yield high production rates: watertemperature through its direct effect on photosynthetic ratesand indirectly in the formation of diurnal mixed layers; lightindirectly through water temperature and directly through itsattenuation and induction of light-adapted physiology in Microcystis.     

Adaptive diversity in congeneric coastal crabs: Ontogenetic patterns of osmoregulation match life-history strategies in Armases spp (Decapoda, Sesarmidae)

Ontogeny of osmoregulation and salinity tolerance were investigated throughout the larval development of two congeneric species of sesarmid crab, Armases ricordi (H. Milne Edwards) and A. roberti (H. Milne Edwards), and compared with previous observations from two further congeners, A. miersii (Rathbun) and A. angustipes (Dana). In the semiterrestrial coastal species A. ricordi, the zoeal stages were only at moderately reduced salinities (17-25.5‰) capable of hyper-osmoregulation, being osmoconformers at higher concentrations. The megalopa was the first ontogenetic stage of this species, which exhibited significant hyper-osmoregulation at further reduced salinities (≥ 5‰), as well as a moderately developed function of hypo-regulation at high concentrations (32-44‰). The riverine species A. roberti showed similar overall patterns in the ontogeny of osmoregulation, however, also some striking differences. In particular, its first zoeal stage showed already at hatching a strong capability of hyper-osmoregulation in salinities down to 5‰. Interestingly, this early expressed function became significantly weaker in the subsequent zoeal stages, where survival and capabilities of hyper-osmoregulation were observed only at salinities down to 10‰. The function of hyper-regulation in strongly dilute media re-appeared later, in the megalopa stage, which tolerated even an exposure to freshwater (0.2‰). Differential species- and stage-specific patterns of osmoregulation were compared with contrasting life styles, reproductive behaviours, and life-history strategies. In A. ricordi, the larvae are released into coastal marine waters, where salinities are high, and thus, no strong hyper-osmoregulation is needed throughout the zoeal phase. The megalopa stage of this species, by contrast, may invade brackish mangrove habitats, where osmoregulatory capabilities are required. Strong hyper-osmoregulation occurring in both the initial and final larval stages (but not in the intermediate zoeal stages) of A. roberti correspond to patterns of ontogenetic migration in this species, including hatching in freshwater, larval downstream transport, later zoeal development in estuarine waters, and final re-immigration of megalopae and juvenile crabs into limnic habitats, where the conspecific adults live. Similar developmental changes in the ecology and physiology of early life-history stages seem to occur also in A. angustipes. A. miersii differs from all other species, showing an early expression and a gradual subsequent increase of the function of hyper-osmoregulation. This ontogenetic pattern corresponds with an unusual reproductive biology of this species, which breeds in supratidal (i.e. land-locked) rock pools, where variations in salinity are high and unpredictable. Matching patterns in the ontogeny of osmoregulation and life-history strategies indicate a crucial adaptive role of osmoregulation for invasions of (by origin marine) crabs into brackish, limnic and terrestrial environments.     

Larval stages of Brachynotus atlanticus Forest, 1957 (Crustacea: Decapoda: Grapsidae) reared under laboratory conditions

The complete larval development of the Eastern Atlantic grapsidcrab, Brachynotus atlanticus, was obtained in the laboratory.Five zoeal stages, the megalopa and the first crab stage aredescribed and illustrated. Under laboratory conditions at 23°Cthe first crab appeared on the 25th day. This is the first speciesof the genus for which the complete larval development is known.Larval features are compared with those of other members ofthe subfamily Varuninae.     

The Ontogeny of Osmoregulation and Its Neurosecretory Control In the Decapod Crustacean, Rhithropanopeus harrisii (Gould)

Laboratory-hatched larvae of this estuarine crab were rearedat 25°C in seawater of 25 salinity for 18 days coveringzoeal Stages I to IV and a megalops. Three-day periods betweenzoeal stages represent intermolt stages of circadean metecdysis,diecdysis, and proecdysis.Larvae were exposed to either a seriesof seawater salinities from 5-40 in 5 increments or of 10-40in 10 increments for one hour during each day of their development.The osmoconcentrations of 20-80 nanoliter hemolymph samplesfrom each of four larvae were measured separately by determinationsof freezing point depression. Eyestalkless larvae in metecdysis of zoeal Stage II were exposedto the same osmoconcentrations as unoperated controls to testfor osmoregulation by eyestalk nerve tissue. Larvae tend to be isosmotic with seawater of 30-40 salinity(S) and to hyperregulate in more dilute media except for larvaein their first diecdysis which remain isosmotic. Larvae in thelast few hours of proecdysis hyperregulate against 40 S as well,presumably to insure inflow of water to establish a greaterbody volume during hardening of the exoskeleton. They are consequentlyisosmotic in the very early metecdysis. The presence of eyestalks at the first metecdysis (Stage II)keeps zoeas hyperosmotic to 5-30 S, but prevents them from hyperregulationagainst 40 S. Eyestalkless zoeas become isosmotic with 5-30S and hyperregulate against 40 S like late proecdysal larvae.Lack of eyestalks makes diecdysal animals hyperregulate againsta medium with which normal animals are isosmotic. The eyestalkinfluence affects second metecdysal (Stage III) larvae in away similar to those in first metecdysis except that it apparentlyalso prevents a curious tendency to hyporegulate in 5-30 S.Similarly, in this stage, the eyestalks prevent hyperosmosityin 40 S seawater as they do during the first day of zoeal StageII. Eyestalk nerve tissue reduces the degree to which diecdysallarvae of this stage remain hyperosmotic to media of 10 S and20 S and apparently causes larvae to be hypoosmotic at 40 S. Preliminary data indicate that removal of eyestalks has littleeffect on proecdysal larval osmoregulation or on regulationof Stage IV zoeas. In other experiments ablation of eyestalks caused Stage II larvaeto lose the ability to osmoregulate against 10-30 S seawaterwithin two hours after the operation. The same zoeas did nothyperregulate against 40 seawater until four hours after removalof eyestalks.     

Horizontal distribution and dominant species of heteropods in the East China Sea

This article discusses the horizontal distribution and dominantspecies of heteropods in the East China Sea. The ecologicalcharacteristics of heteropods and their adaptability to theenvironments were also considered. Oceanographic census wascarried out in the East China Sea (23°30 '33° N and118°30'128° E) in four seasons from 1997 to 2000. Itwas found that the total abundance showed obvious seasonal variations.It peaked in autumn with a mean value of 21.03 ind. (100 m³)^–1,followed by summer (4.89 ind. (100 m³)^–1). The lowestabundance occurred in winter and spring. As to the horizontaldistribution, abundance in summer and autumn was higher in thenearshore than in the offshore of the East China Sea. In winterand spring, heteropods were barely found in the northern nearshore.Three dominant species were observed in four investigated seasons,in which only Atlanta rosea dominated in winter, spring andsummer while Atlanta peroni and Atlanta lesueuri mainly dominatedin autumn. These two dominant species observed in autumn exhibiteda rather higher occurrence frequency than A. rosea. Temperaturewas found to be a major influencing factor whereas salinitywas a minor one. Comparing their adaptability, A. rosea cansurvive in a wider temperature range (1628°C), which enablesit to dominate in four seasons, while A. peroni survives ina relatively narrow temperature range (1928°CC) and therange for A. lesueuri was even more narrow (2128°CC). Moreover,A. rosea was also adapted to a wider range of salinity. However,the abundance of A. rosea in autumn was lower than those ofA. peroni and A. lesueuri. It can be thereby inferred that themultiplication speed of A. rosea was lower than the other twospecies within the same favorable temperature range. Due totheir adaptability to high salinity, the distribution of heteropodswas closely related to the domain of the Taiwan Warm Currentand Kuroshio. Especially for A. peroni and A. lesueuri, theirhigh abundance areas are always indicative of the lasting existenceof strong warm currents. The negative values of aggregationindices indicated relatively even distribution of heteropodsin the East China Sea. The high abundance area (31°00' N,126°00' E) of heteropods in autumn is on the migration pathwayof the mackerel (Scomber japonicus Houttuyn). Thus, there isalso a fishing ground of the mackerel. This suggested that thehigh abundance area of heteropods in autumn is important tothe fisheries in the East China Sea. Comparing with the historicalrecords, the abundance of heteropods appeared to increase inthe past 40 years. This may be a result of strengthened warmcurrents due to global warming.     

Natural occurrence of phycoerythrocyanin-like pigment in cyanobacterial blooming samples dominated by Microcystis in Lake Kasumigaura

We describe the occurrence of phycocyanin and phycoerythrocyanin-likepigment in natural Microcystis colonies collected in Lake Kasumigaura.For differentiating pigments, the combination of simultaneousdetermination of molecular weights of and ß and subunitsby electrospray ionization mass spectrometry with HPLC separationand fluorescence measurements was used. It was suggested thatthe natural Microcystis colonies may contain the phycoerythrocyanin-likepigment, judged from the excitation and emission spectra. Measuredpigments consisted of different molecular weights of and ßsubunits, but the molecular weights of and ß subunitsin both phycocyanin and phycoerythrocyanin-like pigments werenot always identical.