Fungi from the Sargasso Sea

Fungi inhabiting Sargassum spp. from the Sargasso Sea were examined. Three ascomycetes were found, two of which are new records for this environment. Haloguignardia oceanica (Ferdinandsen et Winge) Kohlm. comb. nov. was collected only once before, over 50 years ago. Haloguignardia tumefaciens (Cribb et Herbert) Cribb et Cribb was known only from Australia and New Zealand. Imperfect states of these ascomycetes and fruiting bodies (acervuli) of a hyperparasitic deuteromycete (cf. Sphaceloma sp.) were found for the first time in the galls of the two species. Lindra thalassiae Orpurt et al., previously known only from the sea grass Thalassia testudinum Köngig, develops in air bladders of Sargassum sp., causing a shedding of infested vesicles. Possible reasons for the rarity of fungal species and diseased plants in the Sargasso Sea are diseussed.Dedicated respectfully to my teacher, Professor Dr. H Drawert (Universität Famburg), on the occasion of his 60th birthday.     

Plasticity in circadian activity patterns of mesocarnivores in Southwestern Europe: implications for species coexistence

Limiting similarity theory predicts that competing species must segregate along one or more dimensions of their ecological niche in order to coexist. In predator communities, interspecific interactions are influenced by a diversity of factors; therefore, the behavioural patterns of composing species will differ due to locally adapted interactions. We deployed 32–41 camera-traps in five study areas across the Iberian Peninsula to investigate the temporal relations between mesocarnivores in SW Europe. The selection for a period of the diel cycle and plasticity in activity patterns was evaluated using the Jacobs Selection Index (JSI) and the coefficient of activity overlap (?₁). Furthermore, we investigated whether temporal shifts can facilitate coexistence by reducing activity overlap. Seven species of mesocarnivores were detected and were assigned into one of three behaviourally distinct groups: diurnal (JSI_day?≥?0.8), strictly nocturnal (JSI_night?≥?0.8) or facultative nocturnal species (0.4?≥?JSI_night?>?0.8). Most species exhibited substantial flexibility, which allowed them to locally adapt their foraging strategies (intraspecific ?₁?=?0.70–0.77). Mean Δ₁ from all interspecific pairwise comparisons was negatively correlated with the number of carnivore species with ≥10 detections (r ?0.76, p?=?0.02). Our results suggest that temporal segregation is likely to play an important role in facilitating mesocarnivore coexistence, especially with increasing community complexity, where most species’ activity peaks were asynchronous. These results contribute to understanding the dynamics and behavioural strategies of coexisting mesocarnivores, crucial for forecasting the possible outcomes of conservation or management actions.     

Laboratory experiments on the diurnal vertical migration of marine dinoflagellates through temperature gradients

The diurnal vertical migrations of 4 marine dinoflagellates (Cachonina niei, Ceratium furca, Gymnodinium splendens, and Prorocentrum micans) were studied in a thermally-stratified Plexiglas column (1.70 m deep, 0.61 m diameter). All species migrated through temperature gradients exceeding 7 C°. Some species exhibited altered migration patterns at different salinities either between experiments or compared to observations by other investigators. P. micans exhibited complex changes in swimming speed that depended both on temperature and on the light cycle. These changes provide insight into the possible time course of a field organism's diurnal exposure to physical variability in the water column. P. micans exhibited compositional changes in response to the light cycle, but not to the cross-thermocline temperature differential. A multi-parameter response matrix is required to model coupling between organisms and biologically-active physical mechanisms realistically.     

Arsenic detoxification potential of <Emphasis Type="Italic">aox</Emphasis> genes in arsenite-oxidizing bacteria isolated from natural and constructed wetlands in the Republic of Korea

Arsenic is subject to microbial interactions, which support a wide range of biogeochemical transformations of elements in natural environments such as wetlands. The arsenic detoxification potential of the bacterial strains was investigated with the arsenite oxidation gene, aox genotype, which were isolated from the natural and constructed wetlands. The isolates were able to grow in the presence of 10 mM of sodium arsenite (As(III) as NaAsO₂) and 1 mM of d+glucose. Phylogenetic analysis based on 16S rRNA gene sequencing indicated that these isolated strains resembled members of the genus that have arsenic-resistant systems (Acinetobacter sp., Aeromonas sp., Agrobacterium sp., Comamonas sp., Enterobacter sp., Pantoea sp., and Pseudomonas sp.) with sequence similarities of 81–98%. One bacterial isolate identified as Pseudomonas stutzeri strain GIST-BDan2 (EF429003) showed the activity of arsenite oxidation and existence of aoxB and aoxR gene, which could play an important role in arsenite oxidation to arsenate. This reaction may be considered as arsenic detoxification process. The results of a batch test showed that P. stutzeri GIST-BDan2 (EF429003) completely oxidized in 1 mM of As(III) to As(V) within 25–30 h. In this study, microbial activity was evaluated to provide a better understanding of arsenic biogeochemical cycle in both natural and constructed wetlands, where ecological niches for microorganisms could be different, with a specific focus on arsenic oxidation/reduction and detoxification.     

Investigations of carotenoids in some fauna of the Adriatic Sea. I. Verongia aerophoba (Porifera: Spongiidae)

Investigations have been carried out on the carotenoids in Verongia aerophoba (Schmidt) (Porifera: Spongiidae) from the Adriatic Sea. The presence of the carotenoids -carotene, -carotene, isozeaxanthin, lutein (ester and free), zeaxanthin, violaxanthin, neoxanthin, astaxanthin and astacene was determined by means of columnar and thin-layer chromatography.     

Diel patterns of emergence of crinoids (Echinodermata) from within a reef at Lizard Island,Great Barrier Reef,Australia

Periods of emergence of nine species (88 individuals) of crinoids (Comanthus parvicirrus, Clarkcomanthus albinotus, Comaster multifidus, Oxycomanthus comanthipinna, Oligometra serripinna, Comanthus gisleni, Comanthus wahlbergi, Comatula purpurea, and Oxycomanthus exilis) were monitored at Lizard Island, Queensland, over seven days in March 1983. One species (O. serripinna) was fully exposed and the others partially exposed. Two patterns of emergence were species-specific: emergent both day and night, and emergent only at night. Intraspecific exposure patterns were generally synchronous in six species and asynchronous in three species. The number of species visible was relatively constant during all dives, while at least twice as many individuals were visible at night compared to day. Degree of emergence was determined as the number and length of arms extended into the water column. Except for species fully exposed, degree of crinoid emergence was generally minimal at midday and maximal at twilight and night. Increases in both number of crinoids visible, and the amount of an individual's emergence, corresponded to decreasing light intensities, even during daytime. It is suggested that the patterns of exposure are a response to increased prey abundance at twilight and night, and also a means of avoiding diurnal predators. Gonads on the longest arms of some partially exposed crinoids were not extended into the water, thus protecting the gonads from predators.     

The annual reproductive cycles of Uca annulipes,Portunus pelagicus and Metapenaeus affinis (Decapoda: Crustacea) from the South-west coast of India

Employing the gonad index method, the reproductive cycles of three decapod crustaceans, Uca annulipes (Latreille), Portunus pelagicus (Linnaeus) and Metapenaeus affinis (Milne-Edwards) have been studied. In these crustaceans breeding is not continuous all the year round, but extends over several months of the year with distinct peak periods of gonadal activity. The male and female reproductive cycles are not concurrent. The peak of the reproductive cycle of males occurs slightly earlier in the breeding season than that of females. These studies indicate the possibility of production of successive broods of eggs during the same breeding season. In these species, the low saline conditions of the monsoon period are unfavourable for breeding. The medium and high saline conditions during the post-monsoon and pre-monsoon months, respectively, with plenty of planktonic food for the larvae, seem to be the favourable periods for breeding activity.     

Antimicrobial activities of marine sponges from French Polynesia and Brittany

Extracts from marine sponges collected in French Polynesia and along the Brittany coast (France) have been tested for antibacterial and antifungal activity. The bioactity is concentrated in Dendrilla sp., Homaxinella trachys, Hyrtios eubamma, Verongia aerophoba and Phakellia ventilabrum. The compound responsible for the activity of H. eubamma has been identified as puupehenone, while that of P. ventilabrum is due to a new sesquiteprenoid isonitrile.This study forms part of the Thèse 3e cycle of Ph. Amade, Université de Bretagne Occidentale     

Are mangroves and seagrasses sources of organic carbon for penaeid prawns in a tropical Australian estuary? A multiple stable-isotope study

The vertical distribution of the larvae of shelf-dwelling fish species that spawn in the NW Mediterranean Sea in spring was studied in relation to environmental data. Two sampling cycles were carried out at fixed stations on the continental shelf in May and June 1992. Three patterns of larval vertical distribution for the various taxa represented in the samples were observed. The larvae of most species (e.g. Boops boops, Diplodus sargus) were mainly located in the surface layer (10 m), others (e.g. Arnoglossus sp.) had broader distributions in the upper 40 m of the water column, and but a few (e.g. Gobiidae) were present in large concentrations at greater depths. The vertical distribution patterns of the various species showed no variations, despite high hydrographic variability during the study. The vertical distribution of only a few species (e.g. Arnoglossus sp., Crystallogobius linearis and Engraulis encrasicolus) varied over the diel cycle. The possible influence of the vertical distribution of fish larvae on their horizontal distribution patterns is discussed. Received: 10 March 1997 / Accepted: 4 April 1997     

Harpacticoid copepod respiration: Enhydrosoma propinquum and Longipedia helgolandica

Oxygen consumption rates of 2 harpacticoid copepods, one benthic, Enhydrosoma propinquum (Brady) and one benthopelagic, Longipedia helgolandica (Klie), were determined and compared with those of the pelagic harpacticoid Euterpina acutifrons. The respiratory rates of the 3 species differed significantly and could be correlated with activity patterns and habitat preferences. E. propinquum consumed the least oxygen, E. acutifrons an intermediate amount, and L. helgolandica the most per unit dry weight. Gravid L. helgolandica had a lower metabolic rate than the non-gravid females. The lower values for the gravid females most likely reflected the metabolic activity of the developing egg mass. Harpacticoids may be important contributors to total meiobenthic metabolism, since they respire more per unit weight than do nematodes.Supported by NSF Grant GB-8189 to Duke University Cooperative Program in Biological Oceanography (BCC) and NSF Grant 7435 (WBV).     

Evaluating day–night changes in shallow Mediterranean rocky reef fish assemblages by visual census

Ecological information on coastal fish distribution patterns and habitat use can be greatly improved by nocturnal samplings and observations. To this purpose, the structure of a Mediterranean fish assemblage inhabiting the shallow rocky littoral of Linosa Island (Sicily Strait, Italy) was examined by using visual census to detect possible diel variations in species composition and abundance. Day–night fish distribution patterns were investigated by multivariate and univariate analyses. Overall, 42 fish taxa belonging to 19 families were recorded: 35 during the day and 24 during the night. Seventeen species were common to both diurnal and nocturnal assemblages. Within the diurnal assemblage, Chromis chromis was the most represented species (37.2%), followed by Thalassoma pavo (23.2%) and Sparisoma cretense (10.8%). Within the nocturnal assemblage, the most abundant taxon was Atherina spp. (33.9%), followed by Apogon imberbis (26.4%) and Boops boops (11.5%). Our results indicated wide variation in the abundance and species composition during the day and during the night. Multi Dimensional Scaling plot showed a clear-cut separation between the two assemblages and analysis of similarities found significant differences as well. SIMPER analysis revealed that ten species individually contributed by more than 2.5% to the dissimilarity between diurnal and nocturnal assemblages, T. pavo, C. chromis and S. cretense being the first three species in order of decreasing percentage. ANOVA performed on species richness and fish abundance detected significant differences between diurnal and nocturnal assemblages, the latter showing far lower average values for both variables.     

Molt cycle alterations in behavior,feeding and diel rhythms of a decapod crustacean,the spiny lobster Panulirus argus

The crustacean molt cycle manifests extensive behavioral changes in addition to physiological and integumentary modifications. The paucity of quantitative studies led us to characterize molt stage dependent alterations in rhythmic locomotor, feeding, and agonistic behavior of subadult spiny lobster Panulirus argus held grouped and solitarily in simulated natural conditions. Non-disruptively determined molt stages were defined as proportions of intermolt duration. Significant nocturnal rhythmicity persisted through the full molt cycle, though daily form varied as a function of activity level and molt stage. A distinct early evening peak signaled initiation of foraging and walking behavior. Thereafter, rhythm amplitude either declined progressively (low activity: unimodal pattern), remained high (high activity: nocturnal plateau), or exhibited a secondary early morning peak (intermediate activity: bimodal and polymodal patterns). Activity ceased at or immediately prior to sunrise. Ecdysis was predominantly nocturnal, probably reflecting species specific spatiotemporal movement patterns and social behavior. A selective advantage of nocturnal ecdysis was postulated concerning avoidance of cannibalism and diurnal predators. Locomotor activity and feeding rates were not equivalent through the molt cycle, though both peaked in stages B₂-C₁. Locomotor activity remained high in metecdysis, decreased sharply at proecdysis initiation (D₀), reaching lowest levels in D₁-D₃, then increased in D₃ through B₁. Activity dropped steeply at ecdysis, though lobsters were capable of intense and coordinated activity. Feeding decreased slowly through metecdysis after the B₂-C₁ maximum, then increased temporarily in C₄ and D₀, indicating heightened feeding motivation. This contrasts with the locomotor activity decrease at proecdysis. Food consumption declined rapidly in D₁ and D₂ and ceased at the D₂-D₃ transition. Feeding resumed in B₁ or B₂, intensifying to maximum in late B₂. Feeding remained relatively constant within stages, whereas locomotor activity varied greatly, though both correlated with metabolic needs. Grouped and solitary lobsters displayed similar patterns of foraging and walking, equivalent to those of locomotor activity and feeding of solitary individuals. Frequency of agonistic interactions (not aggression per se) remained relatively constant through the cycle, peaking in metecdysis, though the highest relative proportion occurred near ecdysis. Lobsters then were submissive and avoided physical contact with conspecifics. Clearly, locomotor activity, feeding, and social behavior of P. argus are not simply determined. Indeed, behavior is distinctly phase coordinated with varying metabolic requirements dependent on the proximity to ecdysis and ecological pressures.     

Diurnal photosynthetic performance of seaweeds measured under natural conditions

Statements comparing photosynthetic performance characteristics of species rely upon empirical data, usually light-saturation curves (photosynthesis, P, versus incidentlight flux-density, I _o, relationships) derived from instantaneous measurements. The specific comparative parameters are initial slope and maximum photosynthesis, P _max. For phytoplankton, diurnal variation in specific productivity at maximum incident light, I _max is typically asymmetrical, i.e., there is a morning maximum followed by an afternoon depression. Five seaweed species, numerical dominants from the Outer Banks of North Carolina, were examined for patterns of diurnal photosynthetic performance in sunlight of habitat equivalence. These were Codium decorticatum (Woodw.) Howe and Ulva curvata (Kütz.) De Toni in the Chlorophyceae, Dictyota dichotoma (Huds.) Lamour. and Petalonia fascia (O.F. Müll.) Küntze in the Phaeophyceae, and Gracilaria foliifera (Forssk.) Børg. in the Rhodophyceae. Diurnal patterns of oxygen exchange were varied, some symmetrical about the midday axis, others asymmetrical, and were specific for (1) species, (2) derived habitat, (3) thallus absorptance (1-I/I _o, where I is the transmitted light), (4) developmental stage, and (5) diurnal photosynthetically active radiation (PAR) history. All species show a depression in oxygen exchange rates at less than 0.1 I _max, and show varying degrees of recovery when I _o decreases from that value. Diurnal photosynthetic performance of some species at 0.03 I _o (total diurnal maximum) exceeds several times that at 0.70 I _o (total diurnal maximum), an observation not predicted by instantaneous measurements. Specific day-rate integrals of I _o vary, producing transient initial slope and P _max values. Thus, initial slope and P _max values derived from instantaneous measurements in the laboratory bear little relationship to actual diurnal production. At this time there appears to be no substitute for direct measurement of diurnal photosynthesis.     

Contrasting feeding patterns among species of fish larvae from the tropical Andaman Sea

Feeding habits of tropical fish larvae were analysed in a comparative study of four species (Scorpaenodes sp., Carangoides sp., Acanthocepola sp. and Cynoglossus sp.) from the Andaman Sea. We investigated morphological characteristics and their potential influence on larval feeding, and looked for common patterns in larval prey preference. Gut contents of a total of 300 larvae were examined and compared with local zooplankton composition. The feeding habits of the investigated larvae shared a number of characteristics. During ontogeny both the preferred prey size and the number of prey in the gut increased, and across all larval size classes the relative prey size spectrum stayed constant, of approximately the same magnitude for all four species. On the other hand, larval feeding also differed in a number of aspects, especially differences in the taxonomic composition of preferred prey were apparent. Scorpaenodes sp. preferred abundant and large prey taxa, Acanthocepola sp. and Carangoides sp. preferred large, but less common prey taxa, while Cynoglossus sp., which had the relatively smallest mouth size, preferred smaller sized prey groups. Hence, the findings indicate that from an offset of common characteristics, especially related to prey size preference, larvae have their individual feeding patterns related to specific morphology and patterns of distribution.Communicated by M. Kühl, Helsingør     

Follicovitellosum indicum,a new trematode,found in the fish Belone belone

A new trematode, collected in 1971 from Ratnagiri, India, is described as Follicovitellosum indicum sp. nov. A new subfamily, Follicovitellotrematinae is created within the family Zoogonidae Odhner, 1911, to receive the new genus Follicovitellosum, with its genotype F. indicum. The new species is characterized by the follicularized nature of its ovary; the ovarian follicles are posttesticular. The vitellarium is further divided into several follicles which are largely in the pre-ovarian zone, but post-acetabular and posttesticular in location.     

Effects of dieldrin in seawater on the development of two species of crab larvae,Leptodius floridanus and Panopeus herbstii

Some of the effets of dieldrin on the development of two species of crabs, Leptodius floridanus (Rathbun) and Panopeus herbstii (Milne-Edwards), were studied. It was found that the larvae of neither species were able to complete their development at 10 ppb dieldrin or higher in seawater. Groups of L. floridanus larvae reared in 1 ppb dieldrin in seawater had a 15 to 27% higher mortality during development to the postlarval stage than controls. The highest mortality occurred during the first zoeal stage. The time of development to the megalopal stage was as much as 11.4% longer among larvae reared in 1 ppb than among controls. The survival of L. floridanus larvae was not affected by 0.5 ppb dieldrin in seawater. The survival of P. herbstii larvae to the first crab stage was not affected by 1 ppb dieldrin in seawater at 28.5 °C, 30%.S. It was concluded that a comprehensive study of the toxicity of a given pesticide to all stages in the life cycle of a species is necessary to give even an incomplete idea of how the pesticide might affect the animal in its natural environment.     

The mouthparts of the members of the Jaera albifrons group of species (Crustacea: Isopoda)

The mouthparts of Jaera albifrons Leach, Jaera ischiosetosa Forsman, Jaera praehirsuta Forsman and Jaera forsmani Bocquet were examined with the light microscope and the Stereoscan electron microscope, and were found to be identical in all species. The structure of the mouthparts indicate that all four species feed by scouring and abrading algal or bacterial films from rocks or Fucus. Food, therefore, does not seem to be an isolating factor involved in the microdistribution of the four species on a shore.     

The life cycle ofClytia attenuata (calyptoblastea: Campanulariidae)

The life cycle of the hydroidClytia attenuata (Calkins) (Calyptoblastea: Campanulariidae) has been completed in the laboratory including development of the medusa, previously described asPhialidium lomae Torrey (Leptomedusae: Campanulariidae). Under laboratory conditions, the hydroid exhibits some morphological variation. Characteristic branching of the hydroid occurs at temperatures between 17° to 19°C. At 13° to 15°C the colonies are unbranched and cannot be distinguished fromClytia cylindrica L. Agassiz. Young medusae are similar to other young species ofPhialidium. Development to the adult form requires 25 to 30 days at 17° to 24°C. The adult medusae are 6 to 10 mm in diameter, watch-glass shaped, and have 20 to 28 tentacles. Based on the adult medusa,Clytia attenuata is maintained as a valid species.     

Strain specificity in a tropical marine sponge

Grafting experiments have provided direct evidence for the occurrence of strain specificity in the marine demosponge Verongia longissima (Carter). All autografts accepted, all xenografts rejected, and there was both acceptance and rejection of allografts. Among allografts, groups of individuals could easily be identified which showed consistent acceptances and rejections of other individuals. The groups were designated as strains. Histological preparations of graft rejections showed the development of a cuticle between the surfaces of the two sponges in contact. The role of specificity in patterns of interactions between sponges in situ has been discussed from an ecological perspective.