Life cycle and growth ofTrichostegia minor (Curtis) in temporary woodland pools (Trichoptera: Phryganeidae)

Larvae of the caddisTrichostegia minor (Curtis) were collected from four woodland pools in The Netherlands, three of which are temporary, from August 1986 till June 1987. Eggs and larvae of this species proved to be very well adapted to drought, freezing, strongly fluctuating pH and alkalinity levels and prolonged oxygen deficit. The life cycle ofT.minor in a small woodland marsh overgrown byCalla palustris took one year. Adult flight period started at the end of May. Oviposition took place independent of water. Hatching of the eggs started in September and was probably induced by immersion. During the larval stage from September until May, 5 instars could be distinguished by the size of the head capsule. Growth of instars I, II and III during autumn was moderate. Most larvae overwintered as instar III or IV. Possibly there was a larval diapause during winter. In spring rapid growth to instar V took place prior to pupation. Growth rate, expressed as the increase of mean individual dry weight was highest from March to April (2.05±0.75% DW.m^–2.d^–1). In extremely shallow water growth in spring was initially more rapid compared to growth in deeper water. During winter the growth rate decreased to 0.038±0.071% DW.m^–2.d^–1. Net annual production based on the changes of momentary biomass was 183.2±31.7 mg DW.m^–2.y^–1 or 177.2±31.3 mg AFDW.m^–2.y^–1. Production loss during the winter season was 75.1±10.8 mg DW.m^–2.y^–1 or 72.3±10.6 mg AFDW.m^–2.y^–1.     

Growth rates and energy demands in captive juvenile arctic foxes Alopex lagopus in Svalbard

Four arctic fox Alopex lagopus pups (two males and two females) were caught at dens when about 25–53 days old and kept in outdoor pens at NyÅlesund, Svalbard. Their growth in body size (as measured by the length of a front foot), increase in weight, and food consumption were monitored from July to December, 1987. The pups grew rapidly and reached 97.5 ± 0.1% of their maximum adult size when they were 99–127 days old. Increase in body weight took longer (130 days). Food consumption generally increased until about 90 days old, after which it was highly variable. Pups consumed on average 266 kcal kg^–1 day^–1 growing 34g/day until 95 days old. Subsequently, until about 200 days old, they consumed 202 kcal kg^–1 day^–1 and grew 6.8 g/day.     

A comparison of the effects of auxin on cluster root initiation and development in Grevillea robusta Cunn. ex R. Br. (Proteaceae) and in the genus Lupinus (Leguminosae)

The effect of NAA (naphthaleneacetic acid) on the development of cluster roots in members of the Proteaceae and Leguminosae was investigated. The exogenous addition of NAA led to initiation of cluster roots in phosphate conditions normally inhibitory for their development, but initiation took place within the limits of the cluster pattern under –P conditions. There was no change in spacing within the cluster root nor between cluster roots in Grevillea robusta Cunn. ex R. Br. or in rootlet length or cluster root length. In Lupinus albus L., change in rootlet length and cluster root length was noted at 10^-10 and 10¹² M NAA. In L. albus, the length of time that roots were exposed to NAA does not appear to be important, with similar levels of cluster root initiation after 48 h and 7 days. Cluster root production in G. robusta differed from that in L. albus in terms of the concentration of NAA needed to induce initiation, and in the effects of extremely low levels of NAA on rootlet numbers and lengths. L. arboreus L. does not produce cluster roots under –P conditions. Furthermore, neither L. arboreus L., L. angustifolius L., L. luteus L. nor L. mutabilis L. were induced to produce cluster roots under –P conditions, nor under +P conditions in the presence of exogenous NAA. Thus, exogenous NAA only leads to the induction of cluster roots, at levels of P normally inhibitive of their development, in species of Lupinus that produce them under –P conditions. Auxin-induced cluster roots develop within the same constraints as those developing under –P conditions. NAA does not induce cluster roots in species of Lupinus that do not produce them under –P conditions.     

Seasonal and spatial variability of coccolithophore export production at the South-Western margin of Crete (Eastern Mediterranean)

Six moorings were deployed at different locations in the deep submarine canyons along the south–west margin of Crete, providing a total of eight sediment-trap time series from June 2005 to May 2006. Within this dataset, we analyzed the record from intact coccospheres, which represent the signal of export production from the coccolithophore community. The most abundant species at all stations during the whole investigated period were E. huxleyi and A. robusta, followed by S. pulchra HET, G. flabellatus, H. carteri, F. profunda, S. pulchra HOL oblonga, while the rest of the species represented ≤ 1% of the assemblage. Overall the assemblage composition was comparable at all stations, with slight variations mostly related to the different preservation of coccosphere integrity at the different collection depths. The consistent pattern of seasonal variation in species distribution and total coccolithophore export allowed us to define the occurrence of three main periods: a) March to June, with high overall coccosphere flux (up to 4.3 × 10⁵–3.4 × 10⁶ coccospheres m^− 2 day^− 1), increased abundance of E. huxleyi and subordinate H. carteri s.s., Umbilicosphaera spp. and S. pulchra; b) June to November, with high but gradually decreasing total coccosphere flux (up to 7 × 10⁵–1.4 × 10⁶ coccospheres m^− 2 day^− 1) and high relative abundance of the deep photic zone species A. robusta, F. profunda, G. flabellatus as well as S. pulchra and Coronosphaera spp., R. clavigera, U. tenuis, D. tubifera and holococcolithophores; c) November to February, with low overall export fluxes (3.5–9 × 10⁴ coccospheres m^− 2 day^− 1) and high relative abundance of A. robusta, S. pulchra and Syracosphaera spp. These three periods correspond to the seasonal changes in sea surface temperature, surface mixed layer depth and rainfall and are associated with varying total surface primary production, as detected through remote sensing in the surface waters.     

A facile procedure for efficient plantlet regeneration from self-incompatible hybrids in Antirrhinum

A rapid and efficient regeneration system has been developed for interspecific self-incompatible hybrids between Antirrhinum majus×A. hispanicum. Multiple shoots were induced from hypocotyls explants on Murashige and Skoog medium or Loblolly pine medium supplemented with a low concentration of 3-indoleacetic acid (0.05 mg l^–1) and a high concentration of 6-benzyladenine (1 mg l^–1). Rooting took place in 1/2 Murashige and Skoog medium without growth regulators. By using this procedure, it takes about 5–6 weeks from seed to plantlet. The hypocotyls also had a potential to expand and form callus, providing a source for a continuous supply of multiple shoots from the calli at periodic intervals.     

Cultivation and carrageenan yield and quality ofKappaphycus alvarezii in the waters of Vietnam

The carrageenan-producing red algaKappaphycus alvarezii (Doty) Doty was brought to Vietnam from Japan in 1993. Branch fragments of this species were cultivated in a pond, lagoon, inlet and offshore in Vietnam for the first time. The best daily growth rate (DGR) of plants grown in the lagoon area attained 9–11 % day^–1 in May to June (cold season). The water temperature and salinity in this area ranged from 27.2–32.4 °C and 31.4–33.7 °C, respectively. DGR of plants grown in the inlet ranged from 7 to 9% day^–1 in June. Grazing by fish has been observed to occur in this area. The DGR of plants grown in the pond ranged from 5–6% in January–July, but decreased to less than 4% day^–1 in August (hot season). K. alvarezii in Vietnam showed a carrageenan yield of 18.8–24.6% and gel strength of 1566–1712 g cm^–2. These values are similar ones obtained fromK. alvarezii cultivated in the Philippines and Indonesia.     

Life cycle and production of Hydrobia acuta Drap. (Gastropoda: Prosobranchia) in a hypersaline coastal lagoon

The life cycle and annual production of Hydrobia acuta was studied in a hypersaline lagoon (s = 39 in summer), forming a part of solar salt works. Quantitative random samples were taken at regular intervals over a period of 15 months using a corer, and snails collected were counted and measured. Weight and biomass was calculated from a length-weight relationship and from measurements of ash content. H. acuta was a strictly annual species in the study lagoon. Recruitment takes place over a brief period in May and June, after which the breeding population dies. Growth of the new generation was slow during summer, probably due to the unfavourably high salinity. A period of rapid growth took place in autumn coinciding with a drop in salinity caused by rainfall. In winter Hydrobia hibernated by burrowing deeply into the sediment. Growth recommenced in spring when the lagoon was reflooded, but by this time the number of survivors was low.The maximum density of snails was 6 000 m^–2 and maximum biomass 500 mg organic dry wt · m^–2. Annual cohort production was estimated as 786 mg organic dry wt · m^–2 · a^–1. These figures are low compared to other studies on hydrobiid snails, and for production in inland waters, but the value for annual P/B = 4.5 is typical for a univoltine species. The relevance of the results to foraging by wading birds (the main consumers), is discussed.     

Shoot Regeneration from Immature Cotyledons of Cicer Arietinum

Shoot regeneration was achieved from immature cotyledons of five chickpea (Cicer arietinum L.) genotypes: C235, ICC4971, ICC11531, ICC12257 and ICC12873. The cotyledons cultured on Murashige and Skoog (MS) medium supplemented with 3 or 5 mg dm^–3 zeatin with or without 0.04 mg dm^–3 indole acetic acid (IAA) showed formation of cotyledon like structures (CLS) at their proximal ends. Subsequently, shoot regeneration took place in some of the CLS forming explants. CLS were also formed in cotyledons cultured on MS + 0.2 – 1 mg dm^–3 thidiazuron (TDZ); direct shoot regeneration was observed in cotyledons cultured on 1 mg dm^–3 TDZ. The shoot buds elongated on media containing indole butyric acid (IBA), benzylaminopurine (BAP) and gibberellic acid (GA₃). Complete plantlets were obtained by rooting of shoots following pulse treatment with 200 mg dm^–3 IBA for 5 min and culture on growth regulator free half-strength MS medium.     

Life history, population dynamics and production of eastern mosquitofish, Gambusia holbrooki (Pisces, Poeciliidae), in rice fields of the lower Mondego River Valley, western Portugal

The introduced population of Gambusia holbrooki from the rice fields of the lower Mondego River Valley, Portugal, was studied for 15 months, relating their life cycle and population dynamics with its production, in order to assess the role of the species in the energy flow and secondary production in this type of agro-ecosystem. Two main annual cohorts (1995 and 1996 cohorts) were identified. The females outnumbered males and the average female/male-ratio was 4. The inspection of ovary developmental stages of this viviparous fish, revealed that the most important reproductive period was between April and August. The first recruits were recorded in June and were present thereafter until October. Males from the parental cohort died before August, whereas parental females could survive until October. Mean adjusted fecundity (number of embryos divided by female standard length) peaked in July 1996 (0.95) and in June 1997 (1.05). Females reached greater sizes, had a higher growth rate and lived longer than males. Annual production was estimated at 3.101 g.m^–2.year^–1 (ash-free dry weight, AFDW), the average biomass at 2.896 g.m^–2 (AFDW), and the P/B ratio was 1.071. A conjugation of life history, population dynamics, production and ecological traits (e.g. fast growth, reduced longevity, viviparity, high productivity, an intermediate position in food chain, and no special habitat requirements for reproduction) clearly show that the populations of G. holbrooki, introduced into rice fields all over the world, may play an important role in the structure and functioning of the biological communities of these important agro-ecosystems.     

Hydraulic conductivities of competing root systems of Grevillea robustaand maize in agroforestry

Models of water uptake in mixed stands of vegetation commonly assume that water is partitioned among competing root systems in proportion to relative root length densities. Such an approach assumes implicitly that roots of different species have equivalent hydraulic properties. This was tested for root systems of Grevillea robustaA. Cunn. and maize (Zea maysL.) at a semi-arid site in Kenya. The hydraulic conductances for roots of both species were measured in situat the scale of the whole root or root system using a high pressure flow meter (HPFM). Hydraulic conductivities (_r) were expressed per unit root length. Root lengths were estimated for maize plants by soil coring and for G. robustausing a fractal branching model calibrated against soil coring. Mean _r was 1.88×10^–7 ±0.28×10^–7kg s^–1 MPa^–1 m^–1 for G. robustaand 1.25×10^–7 ±0.13×10^–7kg s^–1 MPa^–1 m^–1 for maize. Values of _r were not significantly different (P<0.05), suggesting that the assumption of hydraulic equivalence for root systems of the two species may be valid, at least when hydrostatic gradients are the major driving force for water uptake. Differences in conductivities between these species could arise, however, because of variation in the hydraulic properties of roots not accounted for here, for example because of root age, phenology or responses to the soil environment.     

Elevated spring temperature stimulates growth, but not smolt development, in anadromous Arctic charr

Parr–smolt transformation and growth were studied in captive offspring of anadromous Arctic charr (Salvelinus alpinus) from the Hals watercourse in northern Norway (70°N), held either at a natural temperature (< 1 °C until May) or at a temperature elevated to 6 °C in late March. In mid-May, 5 weeks after the increase in photoperiod from 8:16 h light:dark to continuous light, gill Na⁺, K⁺-ATPase activity started to increase in both temperature groups, concurrent with the final development of full seawater tolerance. Temperature had no effect on the development of gill Na⁺, K⁺-ATPase activity, or on hypoosmoregulatory ability. The fish in both treatments resumed growth in mid-May, but from then on growth was faster in the elevated than in the ambient temperature group. In the former group, fish mass doubled in 6 weeks (from 65 to 137 g), and growth ceased at the time when the fish were about to complete their parr–smolt transformation. These findings show that an early vernal temperature increase advances the seasonal growth cycle, but not the parr–smolt transformation, in anadromous Arctic charr.     

Seasonal changes in the chemical and gelling characteristics of agar from Gracilaria verrucosa collected in Turkey

The chemical and gelling properties of agar from G. verrucosa collected from Izmit bay in Turkey at different months of the year were studied. Purification of agar was performed by using amylase treatment and isopropyl alcohol precipitation. The phycocolloid content was between 24.0–43.0% of the algal dry weight and was maximum in summer collected algae. Relative total sulfate and 3,6-anhydrogalactose content in the agar were determined from the ratios of infrared spectroscopy band intensities at 1250/2920 cm^–1 and 930/2920 cm^–1, respectively. 3,6-anhydrogalactose and sulfate contents were the highest in agar from algae collected from June until November and January until July, respectively. The gel strength of native agar were the highest from in autumn collected algae and increased to about 1250 N m^–2 after alkali treatment. Thus, this study demonstrated that G. verrucosa from Turkey produces an agar with optimal chemical and gelling properties after alkali-treatment in fall and winter collected algae and may be used for industrial agar production.     

Seasonal migrations of the common Goby,Pomatoschistusmicrops (Kroyer), in Morecambe Bay and elsewhere

Summary Seasonal changes in abundance, and also reproduction, of the gobiid Pomatoschistus microps in intertidal pools on mussel beds at Morecambe, Lancashire, were studied from 1956 to 1961. During winter the shore was largely vacated by this species which returned for breeding purposes in spring. Spawning took place in upper shore pools from April to August. After a planktonic life of between 6–9 weeks, young fishes were recruited to the demersal population usually from June to September. A correlation between seasonal migrations and sea temperature is postulated. Geographical variation in occurrence and extent of migration in P. microps and the related sublittoral P. minutus is considered in relation to minimum winter sea temperatures over the southern Boreal and Baltic sea areas. Offshore winter migration has been found to take place in areas where such temperatures normally fall below 5° C, but not where minimum sea temperature is above 7° C. The effect of the severe winter of 1962–63 on certain populations of P. microps is described.     

Growth rates of North Sea macroalgae in relation to temperature,irradiance and photoperiod

Three eulittoral algae(Ulva lactuca, Porphyra umbilicalis, Chondrus crispus) and one sublittoral alga(Laminaria saccharina) from Helgoland (North Sea) were cultivated in a flow-through system at different temperatures, irradiances and daylengths. In regard to temperature there was a broad optimum at 10–15° C, except inP. umbilicalis, which grew fastest at 10 °C. A growth peak at this temperature was also found in four of 17 other North Sea macroalgae, for which the growth/temperature response was studied, whereas 13 of these species exhibited a growth optimum at 15 °C, or a broad optimum at 10–15 °C. Growth was light-saturated inU. lactuca, L. saccharina andC. crispus at photon flux densities above 70 µE m^–2s^–1, but inP. umbilicalis above 30 µE m^–2s^–1. Growth rate did not decrease notably in the eulittoral species after one week in relatively strong light (250 µE m^–2s^–1), but by about 50 % in the case of the sublittoralL. saccharina, as compared with growth under weak light conditions (30 µE m^–2s^–1). In contrast, chlorophyll content decreased in the sublittoral as well as in the eulittoral species, and the greatest change in pigment content occurred in the range 30–70 µE m^–2s^–1. Growth rate increased continuously up to photoperiods of 24 h light per day inL. saccharina andC. crispus, whereas daylength saturation occurred at photoperiods of more than 16 h light per day inU. lactuca andP. umbilicalis.     

Influence of culture temperature on the growth,biochemical composition and fatty acid profiles of six Antarctic microalgae

The growth, biochemical composition and fatty acid profiles of six Antarctic microalgae cultured at different temperatures, ranging from 4, 6, 9, 14, 20 to 30 ^∘C, were compared. The algae were isolated from seawater, freshwater, soil and snow samples collected during our recent expeditions to Casey, Antarctica, and are currently deposited in the University of Malaya Algae Culture Collection (UMACC). The algae chosen for the study were Chlamydomonas UMACC 229, Chlorella UMACC 234, Chlorella UMACC 237, Klebsormidium UMACC 227, Navicula UMACC 231 and Stichococcus UMACC 238. All the isolates could grow at temperatures up to 20 ^∘C; three isolates, namely Navicula UMACC 231 and the two Chlorella isolates (UMACC 234 and UMACC 237) grew even at 30 ^∘C. Both Chlorella UMACC 234 and Stichococcus UMACC 238 had broad optimal temperatures for growth, ranging from 6 to 20 ^∘C (μ = 0.19 – 0.22 day^–1) and 4 to 14 ^∘C (μ = 0.13 – 0.16 day^–1), respectively. In contrast, optimal growth temperatures for NaviculaUMACC 231 and Chlamydomonas UMACC 229 were 4 ^∘C (μ = 0.34 day^–1) and 6–9 ^∘C (μ = 0.39 – 0.40 day^–1), respectively. The protein content of the Antarctic algae was markedly affected by culture temperature. All except Navicula UMACC 231 and Stichococcus UMACC 238 contained higher amount of proteins when grown at low temperatures (6–9 ^∘C). The percentage of PUFA, especially 20:5 in Navicula UMACC 231 decreased with increasing culture temperature. However, the percentages of unsaturated fatty acids did not show consistent trend with culture temperature for the other algae studied.     

Limnological control of brine shrimp population dynamics and cyst production in the Great Salt Lake, Utah

In the Great Salt Lake of Utah, the brine shrimp Artemia franciscanaKellogg is an important food resource for birds and they produce dormant cysts that are harvested and used extensively in the aquaculture industry. We analyzed the limnological factors controlling Artemia growth and cyst production over 12 months in 1994 and 1995. Laboratory experiments showed that inter-brood intervals were highly dependent on temperature and slightly on food level. At optimal temperatures and nutritious food, juveniles reached reproductive size within 7 d in the laboratory. In winter when temperatures were less than 3 °C, Artemia were absent from the lake, phytoplankton abundance was high (13 Chl a g l^–1), and the dominant grazers were ciliated protozoans. In the spring, cysts hatched when phytoplankton was abundant (15–30 g Chl a l^–1), and the Artemia grew and produced large clutches of ovoviviparous eggs. Estimated naupliar production from these eggs was 80 l^–1 from April to May. Despite the high production of nauplii, Artemia densities declined to 8 l^–1by June and the growing shrimp population grazed down the phytoplankton resource to <1 g Chl a l^–1. With the depleted phytoplankton food resource during the summer, Artemia growth slowed, lipid indices decreased, clutch sizes declined, and females switched primarily to oviparous cyst production. During the summer, there was limited production of ovoviviparous eggs, and limited recruitment of juveniles, probably due to low food. Although oviparous reproduction began in June, more than 90% of the cysts were produced after July when female densities had declined to 1.5 l^–1, but nearly all of them were producing cysts. Estimated cyst production was 650000 m^–2, or 4.54 × 10⁶ kg dry weight for the entire lake. The reported commercial harvest took 21% of the 1994 cyst production. That harvest had little impact on the subsequent year's population, as Artemia densities were ultimately controlled by algal production in the lake.     

Isolation and study of two strains ofLeptospirillum-like bacteria from a natural mixed population cultured on a cobaltiferous pyrite substrate

Two strains ofLeptospirillum-like bacteria, L6 and L8, have been isolated from a mixed inoculum, also containingThiobacillus ferrooxidans andT. thiooxidans, cultured for one year with a colbaltiferous pyrite as energy substrate in a 100 I continuous bioleaching laboratory unit. Several physiological properties of the strains are described. The vibrio-shaped microorganisms grew at pH values lower than 1.3. Their growth rate was maximum between 2.5 and 8.0 g l¹ ferrous iron. The optimal growth temperature was 37.5° C. Ferric iron had a stimulative effect on bacterial development up to 8 g l^–1, and growth was as rapid at 14 g l^–1 ferric iron as at 8 g l^–1. The negative influence of cobalt on the final cell concentration was observed at 0.5 g l^–1, but the growth rate was not affected up to 2 g l^–1. The G + C content of strains L8 is 55.6 mol%.     

Culture ofGelidium sesquipedale (Clem.) Born.et Thur. in a chemostat system. Biomass production and metabolic responses affected by N flow

Gelidium sesquipedale is the most important raw material used for extraction of agar in Spain. Based on chemostats, a system of culture for macroalgae with a continuous flow of culture medium has been developed. A stressed morphotype from the South of Spain was cultured, and the effects of different rates of NO ₃ ^– flow on growth and internal constituents were investigated in the laboratory. Cultivation was successful after optimizing factors affecting growth, such as irradiance level, renewal rate and water movement. Mass production was dependent on N supply. With a flow of 35 mol NO₃ ^– g^–1 DW d^–1, optimal values of growth (2.1% d^–1) and biomass yield were obtained. In these conditions, biomass yield resembled the values observed in natural populations (about 500 g DW m^–2 y^–1). When the flow of N was reduced to 15 mol NO ₃ ^– g^–1 DW d^–1, growth rate and biomass yield were reduced three-fold, and were null when N was supplied as 7 mol NO ₃ ^– g^–1 DW d^–1. C:N ratio was an index of the physiological status of the tissue, remaining low when N was sufficient and raised to critical values when N supply was limited. Phycobiliproteins, kept at a constant irradiance level, were affected by N supply, acting as an internal nitrogen reserve, unlike chlorophylla. An effective phycobiliprotein synthesis took place when the flow of N was sufficient. Agar yield, on dry weight basis, was similar as a function of N flow, whereas agar yield of the culture was higher when N was sufficient as a result of growth not being limited by N.This system of culture, commonly used in microalgal studies, may have an important use in macroalgae as a system to obtain biomass of high quality as well as a good tool for physiological studies in conditions of continuous and controlled flow of nutrients.     

Towards an understanding of human impact upon the hydrology of Lake Naivasha,Kenya

The growth of a strain of Moina macrocopa (Straus 1820) isolated from an experimental stabilization pond in Marrakesh, was examined at seven concentrations of algae (6.25–6.25 × 10⁵ cells ml^–1 and at 5 different temperatures (15–30 °C)). Feeding conditions influenced the growth rate as well as the maximum size that reached 1.8 mm at 25 °C and at the highest algal concentration (6.25 × 10⁵ cell ml^–1). The life span and number of moltings reached a maximum (17.4 days and 13 moltings) at average nutrient concentrations (6.25 × 10⁵ cell ml^–1). Juvenile stages varied from 1 to 3 and adult ones from 6 to 8. In the temperature interval tested, growth rate increased with temperature while longevity decreased. Temperature had less effect on maximal size than nutrient availability. Population density (but not crowding) influenced longevity and survival but had no effect on growth.     

First occurrence of Cochlodinium blooms in Sabah, Malaysia

Harmful algal blooms (HABs) resulting in red discoloration of coastal waters in Sepanggar Bay, off Kota Kinabalu, Sabah, East Malaysia, were first observed in January 2005. The species responsible for the bloom, which was identified as Cochlodinium polykrikoides, coincided with fish mortalities in cage-cultures. Determinations of cell density between January 2005 and June 2006 showed two peaks that occurred in March–June 2005 and June 2006. Cell abundance reached a maximum value of 6 × 10⁶ cells L⁻¹ at the fish cage sampling station where the water quality was characterized by high NO₃–N and PO₄–P concentrations. These blooms persisted into August 2005, were not detected during the north–east monsoon season and occurred again in May 2006. Favorable temperature, salinity and nutrient concentrations, which were similar to those associated with other C. polykrikoides blooms in the Asia Pacific region, likely promoted the growth of this species. Identification of C. polykrikoides as the causative organism was based on light and scanning microscopy, and confirmed by partial 18S ribosomal DNA sequences of two strains isolated during the bloom event (GenBank accession numbers DQ915169 and DQ915170).