Natural co-occurrence of Dinophysis acuminata (Dinoflagellata) and Mesodinium rubrum (Ciliophora) in thin layers in a coastal inlet

ABSTRACT. The interdependency of Dinophysis spp., Mesodinium rubrum and Teleaulax spp. has occupied scientists in molecular and ecological domains in recent years. Current knowledge about the predator–prey relationships is based on laboratory investigations. Records on interactions in nature are limited, even though it is known that Dinophysis acuminata and M. rubrum form population maxima in thin layers associated with thermal stratification. We studied the vertical co‐occurrence of these taxa in a stratified coastal inlet in Åland, in the Northern Baltic Sea, SW Finland. Vertical profiles were sampled monthly in the summer of 2008 and observations on diurnal migrational patterns of all species were conducted in September 2008. The population maximum of D. acuminata was almost totally confined to thin layers where the depth maximum of M. rubrum was present. However, this pattern was only observed early in the morning or at noon. The population maxima of M. rubrum and Teleaulax spp. overlapped at noon. Dinophysis acuminata and Teleaulax spp. were restricted to the upper 9 m but M. rubrum was found down to 20 m depth. This study offers circumstantial evidence for the interdependency between the three taxa in nature.     

A key for the identification of the known larval stages of the Mediterranean Brachyura

Summary

Based on the accounts by various authors, an identification key has been constructed for the planktonic zoeae of the 70 species of Mediterranean Brachyura whose larvae are known. The key is based on primary (spines of the carapace, exopodite of the antenna, spines of telson forks) as well as secondary (setation of mouthparts, processes and spines on abdominal somites) morphological characteristics. It allows the identification of the zoeae of 64 species plus those of Liocarcinus genus (six species).     

Phytoplankton community diversity is influenced by environmental factors in the coastal East China Sea

Surface seawater was collected in four different seasons in the coastal East China Sea adjacent to the Yangtze River Estuary and phytoplankton community diversity was analysed using rbcL genetic markers. Phytoplankton diversity (Shannon Index) was found to be highest in autumn and lowest in summer, which was mainly controlled by seawater temperature, river runoff, the Taiwan Warm Current and possibly other environmental factors. For taxa characterized by Form IAB rbcL, the abundance of Chlorophyta was much greater than those of Proteobacteria and Cyanobacteria throughout the year with the most dominant taxa being Bathycoccus prasinos (Chlorophyta) in spring and Micromonas sp. (Chlorophyta) in other seasons. For taxa identified by Form ID rbcL, Coscinodiscophyceae (diatoms) constituted the largest group (most clones) in the phylogenetic tree. Dinophysis fortii (a dinoflagellate) was found to be the most abundant species in winter and spring and Skeletonema spp. (a diatom) dominated the phytoplankton community in summer and autumn. The seasonal dominance of Dinophysis fortii agreed well with the recently increasing proportion of dinoflagellates in the phytoplankton community in the coastal East China Sea. The abundance of Dinophysis fortii was negatively correlated with seawater temperature, suggesting that harmful algal blooms caused by this species may primarily occur in spring.     

Seasonal variation of collected pollen loads of honeybees (Apis mellifera L. anatoliaca)

Pollen collected by honeybees foraging in the region of Bursa, Turkey was analysed for a whole year. Pollen loads were collected from the hives of Apis mellifera anatoliaca once a week and were classified by colour. Forty‐one taxa were identified from the pollen analyses of the loads and 14 of these had percentages higher than 1%. Only 2.05% of the total pollen could not have been identified. Dominant taxa include; Brassicaceae (11.19%), Helianthus annuus L. (10.84%), Cichorioideae (8.93%) Salix spp. (7.99%), Rosaceae (7.37%), Centaurea spp. (7.56%), Papaver spp. (7.41%), Knautia spp. (6.99%), Fabaceae (6.01%), Asteraceae (5.73%), Xanthium spp. (2.65%), Chrozophora spp. (2.45%), Plantago spp. (1.56%) and Acer spp. (1.54%) representing 88.23% of the total. Distinct variations in plant usage are seen through the year with initial use of Rosaceae, Salix, and to a lesser extent Brassicaeae. As these groups finish flowering the bees move onto Helianthus annuus, Centaurea through the summer followed by Asteraceae in the late summer and Fabaceae in the autumn. There is a strong reliance on crop species for pollen forage but a number of indigenous species are also seen within the samples. The most productive period for collecting various pollen types, and the ideal period to determine pollen preferences of honey bees was June‐August.     

On Cannabis indica,Indian hemp

Background: The South Aegean Volcanic Arc (SAVA), one of the most notable geological structures of the Mediterranean Sea, is floristically well known. Nevertheless, the factors that contribute to shaping the plant species richness of the SAVA remain unclear.

Aims: To investigate the factors that affect plant species richness and identify plant diversity hotspots in the SAVA and other central Aegean islands.

Methods: We used stepwise multiple regression to test the relationship between a number of environmental factors and plant species richness in the SAVA, as well as the residuals from the species–area linear regressions of native, Greek and Cycladian endemic taxa as indicators of relative species richness.

Results: The area was confirmed to be the most powerful single explanatory variable of island species richness, while geodiversity, maximum elevation and mean annual precipitation explained a large proportion of variance for almost all the species richness measures. Anafi, Amorgos and Folegandros were found to be endemic plant diversity hotspots.

Conclusions: We have demonstrated that geodiversity is an important factor in shaping plant species diversity in the Cyclades, while mean annual precipitation, human population density and maximum elevation were significant predictors of the Greek endemics present in the Cyclades. Finally, Anafi was found to be a plant diversity hotspot in the South Aegean Sea.     

Trichocytes in Lithophyllum kotschyanum and Lithophyllum spp. (Corallinales,Rhodophyta) from the NW Indian Ocean

The current diagnosis of the genus Lithophyllum includes absent or rare trichocyte occurrence. After examining holotype material, single trichocytes have been revealed to occur abundantly in Lithophyllum kotschyanum Unger, and in freshly collected specimens of Lithophyllum spp. from the Red Sea, Gulf of Aden and Socotra Island (Yemen). Trichocyte occurrence is not considered a diagnostic character at specific or supraspecific levels in the Lithophylloideae, and the ecological significance of trichocyte formation is discussed. The generitype species, L. incrustans Philippi, does not show trichocytes nor do many other Lithophyllum species from diverse geographic localities, but the presence of abundant trichocytes in other congeneric taxa requires emendation of the genus diagnosis. Therefore, the diagnosis of Lithophyllum is here emended by eliminating the adjective “rare” in the sentence concerning trichocyte occurrence, as follows: “Trichocytes present or absent, if present occurring singly.”     

Phylogeography of the Chionodraco genus (Perciformes, Channichthydae) in the Southern Ocean

Antarctic fish of the suborder Notothenioidei represent one of the most notable examples of adaptive radiation in the marine environment. The evolutionary relationships between and within the eight families of this suborder have been well established by numerous studies, whereas the microevolutionary processes of notothenioid species remain largely unexplored. In the present paper we investigated the evolutionary relationships between three closely related species of the genus Chionodraco (family Channichthyidae), namely Chionodraco hamatus, Chionodraco rastrospinosus, and Chionodraco myersi by analysing portions of the mitochondrial genome (D-loop and 16S rRNA). The taxonomic status of C. hamatus and C. rastrospinosus as separate species has been questioned because of the limited number of key morphological characters that distinguish these two taxa. Our results, based on the analysis of several specimens belonging to both morphological groups revealed a small genetic differentiation among haplotypes, however, a clear separation between the two nominal species emerged since all individuals of each of the two taxa clustered together in distinct monophyletic groups. C. myersi appeared more distantly related in the phylogenetic analysis. For one species, C. hamatus, sampling was carried out at three different geographic locations in the area of the Ross Sea and Weddell Sea. The results showed that the partition of the genetic variation within this species is not compatible with the hypothesis of panmixia as gene flow between populations was significantly reduced.     

Trophodynamics of Protomyctophum (Myctophidae) in the Scotia Sea (Southern Ocean)

This study investigated spatial and temporal patterns in distribution, population structure and diet of Bolin's lanternfish Protomyctophum bolini, Tenison's lanternfish Protomyctophum tenisoni and gaptooth lanternfish Protomyctophum choriodon in the Scotia Sea using data collected by midwater trawl during spring, summer and autumn. Protomyctophum bolini was the most abundant species of the genus encountered throughout the Scotia Sea with the greatest concentrations occurring around the Antarctic Polar Front (APF). This species had a life cycle of 2+ years, but spatial differences in population structure were apparent as the I‐group was absent from all regions south of the APF, suggesting that the species does not recruit in the Scotia Sea. Protomyctophum tenisoni occurred mostly in waters characteristic of the APF and was absent from the southern Scotia Sea. It had a limited size range, but there was clear size‐related sexual dimorphism with males significantly larger than females. The species had a life cycle of c. 2 years, but the I‐group (c. 1 year old, 1 November to 31 October the next year) occurred only in regions close to the APF suggesting that recruitment is restricted to these waters. A seasonal southward migration for P. choriodon is likely as the species occurred mostly to the south‐west of South Georgia in summer, but extended to the sea‐ice sectors in autumn. Protomyctophum choriodon had a life cycle of 4+ years in the Scotia Sea and the population was dominated by age classes >3 years old. Larval stages were absent during the surveys for all species. Diurnal variations in vertical distribution were apparent for all three species. Interspecific variations in diet were evident, but all species were primarily copepod feeders, with Metridia spp., Rhincalanus gigas and Calanus simillimus generally dominating their diet. Small euphausiids, principally Thysanoessa spp., were also an important component of their diets, particularly for P. choriodon which had the largest body size. The spatial and temporal variations in diet for both P. bolini and P. tenisoni were broadly consistent with underlying abundance patterns within the mesozooplankton community.     

Diel and Seasonal Changes in the Structure of a Decapod (Crustacea: Decapoda) Community of Cymodocea nodosa from Southeastern Spain (West Mediterranean Sea)

The study of a decapod community in a Cymodocea nodosa meadow from Southeastern Spain (Western Mediterranean Sea) showed a stable structure, in which the families Hippolytidae, Processidae, Majidae and Portunidae were the most abundant and the species Hippolyte niezabitowskii dominated. The animal community was more numerous and diverse during the night, showing the existence of nychthemeral movements, which are essentially related to the trophic behaviour and shelter. In this way, many species increased their abundance as a result of an increasing activity and, also, of an influx of other species and specimens from adjacent sandy bottoms, such as Processa spp. (mainly P. modica) Sicyonia carinata, Liocarcinus spp. (mainly juveniles) and several species of hermit crabs, which were rare or absent during the day. All these changes produced modifications in the dominance curves and in the values of all ecological indices (richness, diversity and evenness). Monthly samples were grouped and ordered (MDS) by the factor “day–night”, which showed slight qualitative and quantitative differences (SIMPER, dissimilarity average of the factor day–night = 61.67). On the other hand, no global seasonal differences have been found (one way ANOSIM), but there was a significant level of similarity between winter and spring, while the summer samples were the most different. The differentiation of the summer 1999 can be attributed to a decrease in species abundance and richness, probably due to the dynamics of the decapod populations and the balance with predators (fishes), while that of the summer 2000, to an anomalous event: the massive proliferation of filamentous algae, mainly Ectocarpus s.l., which modified the environmental conditions.     

Palaeobiogeography of Early Cretaceous (Berriasian–Barremian) calcareous nannoplankton

In order to assess Early Cretaceous nannoplankton biogeography, we studied a series of sites which provide a north–south transect across the Atlantic Ocean, supplemented by sections from the North Sea Basin, Barents Sea, Falkland Plateau, Weddell Sea (Antarctica), Argo Abyssal Plain (NW of Australia) and Neuquén Basin (Argentina). Quantitative assemblage data were gathered from each site for seven time-slices within the Berriasian to Barremian interval, each horizon being determined by a nannofossil datum. Trends in species relative abundance and measures of diversity, evenness and richness provide revealing biogeographic information. A broad, low- to mid-palaeolatitude zone (50°N–50°S) is flanked in both Northern and Southern Hemispheres by distinct high-palaeolatitude zones. Major changes in assemblage abundance and composition occur across a sharp biogeographic ‘front’ at around 50°N and S palaeolatitude. High-palaeolatitude assemblages are lower in species richness and diversity and characterised by the presence of abundant, typically bipolar, taxa (e.g. Crucibiscutum salebrosum). A less distinct biogeographic boundary at 40°N is distinguished by the presence/absence of rarer, but biogeographically significant, taxa, many of which have previously been assigned to Boreal or Tethyan provinces. Continental shelf sites are characterised by lower-diversity assemblages with common to dominant diagnostic taxa, which vary with palaeolatitude: Nannoconus and Micrantholithus at low palaeolatitudes, and Biscutum constans and Zeugrhabdotus spp. at higher palaeolatitudes. The latter two taxa are considered to be indicative of elevated surface-water fertility and the former two may have been similarly adapted. The genus Watznoueria is ubiquitously dominant, giving the populations an unevenness, which appears to be a common feature throughout coccolithophore history.     

Molecular Analysis of Ribosomal RNA Gene of Red Tide Algae Obtained from the Seto Inland Sea

Eleven clones from five species of the planktonic microalgae, (Chattonella antiqua, Chattonella marina, Heterosigma akashiwo, Alexandrium catenella, and Scrippsiella trochoidea), which were collected from the Seto Inland Sea in Japan and from Thailand, were subjected to nucleotide sequence analysis of the D1/D2 domain of the large subunit (LSU) of their ribosomal RNA genes. After amplification by polymerase chain reaction using degenerated primers, whole-nucleotide sequences for the D1/D2 domains of the LSU rRNA gene of 11 microalgae were analyzed. Phylogenic tree analysis using these nucleotide sequences showed each species located in a cluster corresponding to its morphological classification. The nucleotide sequence data for Chattonella spp. suggest that multiple clones of both Chattonella antiqua and Chattonella marina are present in the Seto Inland Sea and that red tide blooms of Chattonella spp. in different years may have contained different clones. Received September 6, 1999; accepted December 16, 1999.     

A standard set of polymorphic microsatellites for threatened mountain ungulates (Caprini,Artiodactyla)

Nearly 70% of the world's mountain ungulate taxa are endangered. The availability of a standard set of DNA markers for forensic and molecular ecology studies would help to establish conservation programs and detect poaching activities of these endangered taxa. We tested 60 published microsatellite primer pairs from bovids (cattle, sheep and goat) on 49 individuals from 11 taxa including six wild goat‐like species (Capra spp.), three divergent wild sheep (Ovis spp.), and two chamois (Rupicapra spp.) species. Approximately 30 microsatellites amplified a microsatellite‐like PCR product in all three genera, and with the exception of ILST097, nearly all the loci were polymorphic within most of the 11 species.     

Morphology of the first zoeal stages of eleven Sesarmidae (Crustacea,Brachyura, Thoracotremata) from the Indo-West Pacific,with a summary of familial larval characters

Summary

The first zoeal stages of eleven species of Sesarmidae from the Indo-West Pacific were obtained from ovigerous females. Those of Labuanium scandens, L. rotundatum, L. trapezoideum, L. politum, Metasesarma aubryi, Pseudosesarma crassimanum, Stelgistra stormi, and Sesarmops impressum, are described for the first time, while the first zoeal stages of Clistocoeloma merguiense, Metasesarma obesum and Sesarmops intermedium are re-described. Larval characters of all these species are compared with previously described ones for the family and morphological features are re-evaluated. Minute spines on the telson of the zoeae are described as a new larval character in Sesarmidae and their presence or absence in other grapsoid groups is discussed. The results demonstrate that a recurrent combination of reliable larval characters distinguishes zoeae and megalopae of the examined sesarmids from the rest of the Grapsoidea. This appears to be consistent with recent studies that redefine the Sesarmidae.     

Morphological and behavioral antipredatory adaptations of decapod zoeae

Summary Zoeae of some species of estuarine decapods are retained in the estuary throughout development while others are exported into nearshore coastal waters. The horizontal migrations of decapod zoeae to coastal waters may have evolved to reduce the probability of encountering planktivorous fishes which are most abundant in the estuary. If so, then the morphological vulnerability of zoeae to fish predation should be inversely related to the number of predators occurring where they develop. Six species of estuarine decapod zoeae were offered to Menidia menidia and Fundulus heteroclitus. The behavioral interactions were observed to determine the prey's vulnerability to predation, and the mode of operation and relative effectiveness of their defenses. Feeding trials and behavioral observations both demonstrated that M. menidia 6–16 mm long preferred Uca minax and Callinectes sapidus zoeae, which are exported from the estuary, to Rhithropanopeus harrisii, Sesarma reticulatum and Palaemonetes pugio, which are retained within estuaries. Pinnotheres ostreum zoeae develop in the lower estuary and fish demonstrated an intermediate preference for the zoeae. Menidia menidia 20–40 mm long showed similar preferences for R. harrisii S. reticulatum, P. ostreum and U. minax as did small silversides. Large-mouthed demersal fish, Fundulus heteroclitus 6–10 mm long, also preferred U. minax to R. harrisii, but more readily preyed on zoeae than did M. menidia. The exported species of zoeae have shorter spines and smaller bodies than do retained zoeae, except P. ostreum which is small, spineless and passively sinks when attacked by fish. Other retained species of zoeae also have postcontact behavioral defenses which enhance the effectiveness of their morphological defenses. Zoeae do not evade attacks by fishes, but fishes quickly learned to avoid zoeae, which increases the effectiveness of the zoeae's antipredatory adaptations.     

Shifts in the composition and distribution of Pacific Arctic larval fish assemblages in response to rapid ecosystem change

The Pacific Arctic marine ecosystem has undergone rapid changes in recent years due to ocean warming, sea ice loss, and increased northward transport of Pacific-origin waters into the Arctic. These climate-mediated changes have been linked to range shifts of juvenile and adult subarctic (boreal) and Arctic fish populations, though it is unclear whether distributional changes are also occurring during the early life stages. We analyzed larval fish abundance and distribution data sampled in late summer from 2010 to 2019 in two interconnected Pacific Arctic ecosystems: the northern Bering Sea and Chukchi Sea, to determine whether recent warming and loss of sea ice has restricted habitat for Arctic species and altered larval fish assemblage composition from Arctic- to boreal-associated taxa. Multivariate analyses revealed the presence of three distinct multi-species assemblages across all years: (1) a boreal assemblage dominated by yellowfin sole (Limanda aspera), capelin (Mallotus catervarius), and walleye pollock (Gadus chalcogrammus); (2) an Arctic assemblage composed of Arctic cod (Boreogadus saida) and other common Arctic species; and (3) a mixed assemblage composed of the dominant species from the other two assemblages. We found that the wind- and current-driven northward advection of warmer, subarctic waters and the unprecedented low-ice conditions observed in the northern Bering and Chukchi seas beginning in 2017 and persisting into 2018 and 2019 have precipitated community-wide shifts, with the boreal larval fish assemblage expanding northward and offshore and the Arctic assemblage retreating poleward. We conclude that Arctic warming is most significantly driving changes in abundance at the leading and trailing edges of the Chukchi Sea larval fish community as boreal species increase in abundance and Arctic species decline. Our analyses document how quickly larval fish assemblages respond to environmental change and reveal that the impacts of Arctic borealization on fish community composition spans multiple life stages over large spatial scales.     

Experimental removal of piscivorous groupers of the genus Cephalopholis (Serranidae) from coral habitats in the Gulf of Aqaba (Red-Sea)

Synopsis Elimination of adult groupers (Cephalopholis spp.) from various reef formations in the Gulf of Aqaba (Red Sea) resulted in replenishment by other predatory fishes of different taxa and only partly (21.6%) by species of the same genus. Three years later, the initial population composition had not been restored. Recolonization by juvenile groupers presumably settling from the plankton was only 11.3%. Censuses of the typical piscine prey of groupers, before and 36 months after the removal of Cephalopholis, showed virtually no change in abundace and species composition.     

THE SEASONAL DISTRIBUTION,ABUNDANCE AND DIVERSITY OF DESMIDS (CHLOROPHYTA) IN A SOFTWATER,NORTH TEMPERATE STREAM1

Suspended and benthic algal communities from a mildly acidic, third-order Rhode Island stream were examined to determine the seasonal distribution, abundance and diversity of the lotic desmids. Within a one-year sampling period, 148 species and 202 subspecific taxa of desmids were identified, representing 23 genera. Species of Cosmarium and Closterium accounted for approximately 70% of the desmids present, and were the most diverse and abundant taxa during all seasons except spring, when Hyalotheca dissiliens was the dominant desmid species. Average abundance and species richness generally were greatest during summer for both suspended and benthic desmids. Most desmids occurred in benthic habitats, and were randomly distributed among substrata. Average seasonal abundance was 7.4 × 10⁴ cells·g^?1 dry wt substratum, among 13 types of substrata. Highest desmid abundance was measured among substrata with intricate morphologies, such as Fontinalis spp., which was associated with 1.2 × 10⁶ desmid cells·g^?1 dry wt substratum, or 1.7 × 10³ cells·cm^?2 substratum. Cell division was observed for 70 desmid taxa, and average seasonal reproduction (based on cell numbers) among all substrata ranged from 4% in winter to 20% during summer. In addition, sexually produced zygospores were found occasionally for H. dissiliens. Desmids were distributed among most substrata examined in this stream, with abundance comparable to reported estimates from softwater lakes and acid bogs. In contrast to established dogma, lotic desmids are not incidental drift organisms, but rather comprise a viable and persistent component of the stream periphyton.     

Mediterranean karst springs: diatom biodiversity hotspots under the pressure of hydrological fluctuation and nutrient enrichment

Abstract

Mediterranean karst springs are affected by strong climatic seasonality, with long, dry and hot summers and are increasingly threatened by anthropogenic pressures. In Sardinia (western Mediterranean Sea, Italy), they are largely unexplored and their biocoenoses are mostly unknown. The diatom flora from two substrates (cobbles and macrophytes) in eight springs of different areas of the island was investigated in summer 2016 and winter 2017. A total of 162 diatom taxa (58 genera) were found of which 27 (17 genera) only on cobbles and 26 (18 genera) only on macrophytes. The most abundant species from both substrates were Achnanthidium minutissimum, Amphora indistincta, Amphora pediculus, Cocconeis euglypta, Planothidium frequentissimum and P. lanceolatum. Overall, 67 taxa (40 genera) were recorded in single sites and some of these taxa showed high affinity with specific environmental conditions. Hydrological stability (water flow permanence), discharge and nutrients were the main environmental factors influencing diatom assemblages. Our results suggest that diatoms can reflect important local factors related to the vulnerability of these spring ecosystems and underline the importance of their preservation both for biodiversity and water quality maintenance.     

Effects of copper on species composition of periphyton in a Sierra Nevada, California, stream

SUMMARY. 1. Changes in species composition of the periphyton of an oligotrophic. Sierra Nevada stream continuously dosed for 1 year at three concentrations of copper (2.5, 5 and 10 μg 1^?1 Cu_T; approximately 12, 25 and 50 ng 1^?1 Cu²⁺) were determined. 2. The numerically most abundant taxa were Bacillariophyceae (Achnanthes minutissima, Cocconeis placentula, Cymbella microcephala, C. sinuata, Fragilaria conslruens, F. crotonensis. Navicula spp., Synedra acus and S. rumpens), and the Cyanophyta Lyngbya spp., a co-dominant during spring and summer. 3. Population densities of Lyngbya spp. were markedly reduced at all test concentrations of copper. Population densities of the principal Chlorophyta (Spirogyra spp. and Cladophora spp.) and the diatom Amphipleura pellucida were reduced at 5 μg 1^?1 CU_T. Of the twenty-two most abundant taxa, sixteen were reduced in abundance by continuous exposure to 10 μg 1^?1 Cu_T. 4. There was no commensurate reduction in standing crop (total number of individuals of all taxa). Achnanthes minutissima, a co-dominant in the control, was the primary replacement species. Other taxa that were more abundant at 5 μg1^?1 Cu_T than in the control were Ceratoneis arcus, Cocconeis placentula, Navicula spp. and Synedra rumpens. Only A. minutissima and Calothrix spp. were more abundant at 10 μg 1^?1 than in the control. 5. Three resemblance measures (Canberra metric, Bray-Curtis and Dice) and diversity (Brillouin's) were evaluated for detecting differences in species composition among experimental stream sections. The Canberra metric, an index sensitive to proportional rather than absolute differences, was the most informative of these indices.     

Potentially toxic and harmful microalgae from coastal waters of the Campania region (Tyrrhenian Sea, Mediterranean Sea)

A total number of 40 potentially toxic microalgae and 5 taxa causing discolorations have been identified along the coasts of the Campania region (South Tyrrhenian Sea, Mediterranean Sea). This number is based on results of over 20 years of research at a coastal station in the Gulf of Naples, 4 years of monitoring activity along the Campania coasts and of a series of scattered and sporadic observations. Several species of the recently erected genera Karenia and Takayama are reported for the first time in the area. Information on the period of highest abundances or most probable period of occurrence indicates the late spring and summer as the periods of maximum risk of harmful events. Despite the variety of potentially toxic species, no human health problems nor fish kills have ever been recorded in Campania. The reasons for this apparent paradox are probably to be found in the ecological factors that regulate the abundance, toxicity and spatial distribution of the potentially harmful species and reflect as well the relatively low number of aquaculture plants in the area.