Atlantic climatic factors control decadal dynamics of a Baltic Sea copepod Temora longicornis

We discovered, using transfer functions, that climatic changes in the Atlantic control the abundance of Temora longicornis , a dominant pelagic copepod of the Baltic Sea. The seawater salinity was increasing and copepod numbers were high from 1960s up to 1970s. Then the freshwater runoff started to increase, which resulted in decreasing salinities and abundance of the copepod. At the end of 1990s, runoffs remained at a high level, and the decrease of surface salinities and Temora leveled off. Due to time lags between variables studied, we also make predictions of changes expectable in early 2000s. The total freshwater runoff to the Baltic Sea followed the North Atlantic Oscillation with an immediate lag. Salinity followed the runoff non-linearly with a lag of 4–9 months. Temora longicornis followed the salinity with a lag of 1–3 months. Predicted abundance of T. longicornis will remain low implicating poor feeding conditions for planktivores. Our study points out the importance of physical factors in control of pelagic environments compared to ecological interactions, such as top-down and bottom-up.     

Species-area curves, diversity indices, and species abundance distributions: a multifractal analysis

Although fractals have been applied in ecology for some time, multifractals have, in contrast, received little attention. In this article, we apply multifractals to the species-area relationship and species abundance distributions. We highlight two results: first, species abundance distributions collected at different spatial scales may collapse into a single curve after appropriate renormalization, and second, the power-law form of the species-area relationship and the Shannon, Simpson, and Berger-Parker diversity indices belong to a family of equations relating the species number, species abundance, and area through the moments of the species abundance-probability density function. Explicit formulas for these diversity indices, as a function of area, are derived. Methods to obtain the multifractal spectra from a data set are discussed, and an example is shown with data on tree and shrub species collected in a 50-ha plot on Barro Colorado Island, Panama. Finally, we discuss the implications of the multifractal formalism to the relationship between species range and abundance and the relation between the shape of the species abundance distribution and area.     

Relative attractiveness of baits to Paratrechina longicornis (Hymenoptera: Formicidae)

Exotic ant incursions are becoming more frequent around the globe, and management with toxic baits is a suitable strategy for most species. Crazy ants, (Latreille) (Hymenoptera: Formicidae), however, are notoriously difficult to attract to commercial baits, which are generally tailored to the preferences of fire ants. We tested P. longicornis preferences for various food types and commercial ant baits. Baits trialed were commercially available products Amdro, Maxforce, Xstinguish (nontoxic monitoring version), Presto, and tuna (in spring water), sugar water (25%), boric acid (1% in 25% sugar water), and deionized water. Tuna and Xstinguish, along with sugar water and sugar water + boric acid, were the most attractive baits to P. longicornis foragers. The granular baits (Maxforce, Amdro, and Presto) were not as attractive to P. longicornis foragers. A decrease in temperature from summer (30 degrees C) to autumn (23 degrees C) trials did not seem to affect the food preferences of P. longicornis. Although P. longicornis recruitment was substantially lower during trials where there was concurrent high native ant abundance and diversity, P. longicornis still recruited to preferred baits in numbers higher than any other species. Given that tuna is impractical for management programs, the effectiveness of boric acid, sweet liquid baits in eliminating P. longicornis colonies should be compared with that of the toxic version of Xstinguish. If both are effective at eliminating colonies, we recommend sweet liquid baits containing boric acid be used for small-scale incursions (one or two nests), but a more practicable solid bait, such as Xstinguish, be used for larger scale incursions (numerous nests).     

Seasonal variation in egg morphology and hatching success in the calanoid copepods Temora longicornis, Acartia clausi and Centropages hamatus

We report here on the seasonal changes in ultramicroscopic morphologyof the eggs of the calanoid copepod Temora longicornis. Duringa field study between 1996 and 1998 in the Menai Strait, easternIrish Sea, T. longicornis produced two types of eggs; hatchingor subitaneous eggs were spawned during autumn–winter,whereas a high proportion of non-hatching eggs (up to     

Population dynamics of calanoid copepods and the implications of their predation by clupeid fish in the Central Baltic Sea

Population dynamics of major Baltic calanoid copepod speciesin the Gotland Basin during the last two decades were characterizedby a decline of Pseudocalanus elongatus associated with decliningsalinities, and an increase of Temora longicornis and Acartiaspp. potentially due to warmer conditions. Additionally thisstudy investigated the effect of predation by the major planktivorousfish species herring (Clupea harengus) and sprat (Sprattus sprattus)for the period 1977–1996 in the Gotland Basin (CentralBaltic Sea). Examination of consumption by these fish speciesin relation to copepod production estimates showed a switchby herring from consuming mainly CV/VI of P. elongatus and T.longicornis, to preying on CII of the latter copepod. This switchwas potentially due to increased competition with the drasticallyincreased sprat stock since the late 1980s. Further, an increasedpredation pressure by sprat on CV/CVI of both copepod speciesin spring resulted in higher copepod mortality rates. In consequence,based on these results we suggest that the increase in the spratstock since the late 1980s contributed to a decline of P. elongatus,and additionally prevented an even more pronounced temperature-drivenincrease in the T. longicornis stock, as was observed for Acartiaspp., which was not significantly consumed.     

Immunization effect of recombinant P27/30 protein expressed in Escherichia coli against the hard tick Haemaphysalis longicornis (Acari: Ixodidae) in rabbits

We investigated the induction of resistance to Haemaphysalis longicornis infestation in rabbits that had been immunized with recombinant H. longicornis P27/30 protein. The success of immunological control methods is dependent upon the use of potential key antigens as tick vaccine candidates. Previously, we cloned a gene encoding 27 kDa and 30 kDa proteins (P27/30) of H. longicornis, and identified P27/30 as a troponin I-like protein. In this study, rabbits that were immunized with recombinant P27/30 expressed in Escherichia coli showed the statistically significant longer feeding duration for larval and adult ticks (P<0.05), low engorgement rates in larval ticks (64.4%), and an apparent reduction in egg weights, which suggest that H. longicornis P27/30 protein is a potential candidate antigen for a tick vaccine. These results demonstrated that the recombinant P27/30 protein might be a useful vaccine candidate antigen for biological control of H. longicornis.     

Vertical distribution of subtropical epiplanktonic copepods

The goal of our project is to increase our knowledge about theco-existence of the numerous small copepod species in the subtropicaland tropical open oceans by combining experimental and fieldstudies. In this paper we present the vertical distributionof the copepod assemblages collected in the upper 100 m of thewater column during a diel cycle at an oceanic site off Bermudain summer 2000. Our quantitative analysis ranged from the grossfeatures of the community to order, genus, species and sex,ending with the population structure for one representativecalanoid (Mecynocera clausii). Total abundance of copepods sampledwith both 63 and 200 µm meshes increased from near thesurface to 100 m depth. Of the four orders, the Calanoida andCyclopoida increased slightly with depth, whereas the Poecilostomatoidahardly occurred in the upper 30 m and then increased by morethan one order of magnitude towards 100 m depth. Harpacticoidashowed even abundance through the vertical column during thenight. Some abundant genera/species displayed hardly any orsmall differences in abundance over the upper 100 m (e.g. Calocalanus,Oithona); that distribution also showed that genera with entirelydifferent motion and feeding behaviour can occupy the same verticalenvironment. A second group appeared to avoid the upper mixedlayer and upper thermocline almost completely (e.g. Oncaea,Mecynocera clausii, Clausocalanus pergens, Eucalanus hyalinus,Haloptilus longicornis). A third limited group seemed to preferthe upper mixed layer (e.g. Clausocalanus furcatus). Some generawere characterized by a paucity of males whereas others hadas many males as females. Our results showed that quantifyingthe distribution and abundance of genera, species and theircopepodid stages seems to be the preferable approach, leadingtowards an understanding of the functioning of the epipelagialcopepod community. We hypothesize that a combination of variables,including feeding behaviour, temperature preference and alsopredation, could determine the ranges of vertical distribution,which would be flexible because of the effect of each of thevariables. It is reasoned that predation was of minor impactin these oligotrophic waters because of the very low abundanceof carnivorous species.     

Dietary shifts in the copepod Temora longicornis during spring: evidence from stable isotope signatures, fatty acid biomarkers and feeding experiments

The calanoid copepod Temora longicornis occurs year-round inthe southern North Sea. Owing to its limited ability to storeenergy, this species relies on a constant food supply. Thus,when the phytoplankton stock as the primary food source is lowin winter and early spring, T. longicornis needs to utilizeother food items. In this study, the feeding strategy of T.longicornis females is elucidated using a broad methodologicalapproach. From March to May 2005 we conducted weekly grazingexperiments using natural plankton (<70 µm) as foodsource. In addition, gut contents, stable isotopes (¹⁵N, ¹³C)and fatty acid composition of the females were analysed, aswas the natural plankton composition. Our data suggest thatfemales were omnivorous during late winter and early spring,switching to a more herbivorous feeding mode with increasingphytoplankton stock in spring. The ¹⁵N values in March/Aprilare the highest reported so far for this species, and we suggestthat they mirror the copepods' trophic level throughout ontogenesisrather than reflecting the feeding history of only the females.T. longicornis adjusted its feeding mode to ambient food conditions,utilizing a broad range of food sources. Experiments, however,revealed strong selection for cells >12.5 µm. Feedingon dinoflagellates was generally intense; diatoms were ingestedmainly in March. Thus, the grazing impact of T. longicorniscan be substantial on those taxa, which are selected for.     

Nutritive Value and Selection of Food Particles by Copepods During a Spring Bloom of Phaeocystis sp. in the English Channel, as Determined by Pigment and Fatty Acid Analyses

In this study phytoplankton pigments and fatty acids were usedas biomarkers to study trophic relationships between phytoplanktonand zooplankton. These markers permit the characterization ofboth suspended matter and copepods, allowing examination ofthe transfers from food to zooplankton. A drogue study was carriedout to follow a water mass in the coastal waters off the easternEnglish Channel over a 3-day period, with samples collectedevery 3 h. The study focused on the dominant calanoid copepodspecies: Temora longicornis, Acartia clausi and Pseudocalanuselongatus. Our study was performed during the spring phytoplanktonbloom when solitary cells of Phaeocystis sp. formed 90% of thetotal phytoplankton. Fatty acid analyses provided an indicationof the low nutritive value of these algal cells; in contrastto other algal species which had higher nutritional value (e.g.colony-forming diatoms, Cryptophytes and dinoflagellates). Ourresults suggest that all species selectively grazed on Phaeocystissp. and non-selectively on diatoms. Dinoflagellates were avoidedby all species. Temora longicornis selectively grazed on Cryptophytes,which may be related to the nutritional value of this algae.The fatty acid composition of the three copepod species indicatedan ‘herbivorous’ diet for P.elongatus and an omnivorousone for A. clausi and T. longicornis, which is less opportunist.     

Resources exploitation by ants facilitates lizard egg survival

Abstract.  1.  This study investigated the interaction between eggs of the lizard Mabuya longicaudata Hallowell and two species of ant: a lizard egg commensalist ( Paratrechina longicornis Latreille), and an egg predator ( Pheidole taivanensis Forel). The ecological interaction between P. longicornis and lizard eggs was tested, and it was predicted that when the interaction was removed, lizard eggs would be attacked by P. taivanensis .
2. Field observations showed that both ant species actively searched for lizard eggs, and that P. taivanensis typically found new lizard nests earlier than P. longicornis did. Left undisturbed, P. taivanensis predation dramatically reduced lizard egg survival. While P. longicornis usually found nests later, they were able to displace P. taivanensis . As a result, proportional egg survival was higher in nests with P. longicornis (0.95 ± 0.04 eggs) compared to nests without either ant species (0.65 ± 0.09 eggs), or nests occupied by P. taivanensis (0.07 ± 0.02 eggs).
3. When P. longicornis ants were experimentally excluded from lizard nests, the proportion of eggs surviving significantly decreased because of increased P. taivanensis predation. Paratrechina longicornis benefits from water that condenses on the eggs. When this resource disappears P. longicornis abandons the nest, leading to predation of the eggs by P. taivanensis .     

The structure and diversity of the animal communities in a broadland reedswamp

The fauna of a Phragmites reedswamp at Alderfen Broad, Norfolk, is described in terms of structure and diversity. Three transects were laid parallel to the water's edge at 1 m ( T1 ), 10 m ( T2 ) and 25 m (T3) from the reedswamp/open water interface. Twenty samples were taken randomly along each transect in July and all the macroinvertebrates in the samples were collected. The pH at each site was measured. The pH fell from 8–4 at T1 to 6–4 at T3 .
The fauna of the three transects was analysed by recurrent groups and by plotting the log abundance against the frequency for each species and dividing the resulting graph into units in terms of abundance and frequency. Both methods gave very similar results but the recurrent groups analysis only gave information on the most frequent species. The recurrent groups of the three transects had no common elements. The abundance/frequency analysis is simple to perform and could be of considerable use in evaluating sites for conservation purposes.
Transect T2 had the greatest species diversity, equitability and evenness, T3 the least. Reasons for this are discussed.     

Interspecific and intraspecific associations of two species of hard ticks, Haemaphysalis longicornis and Haemaphysalis megaspinosa, in relation to questing site

The effects of intraspecific and interspecific interactions on preferred questing sites of ticks, specifically nymphs and larvae of Haemaphysalis longicornis and Haemaphysalis megaspinosa, were examined in Boso Peninsula of central Japan from October 1996 to September 1999. Haemaphysalis longicornis were primarily segregated from H. megaspinosa by season. All stages of the 2 tick species preferred sedges. Three-way contingency tables and log-linear models were used to test for independence of occurrence and to quantify associations between species and stages with similar host ranges. The shifts of questing site from leaves to stem tips and from 40-49 cm to greater heights were observed in both species, which suggests that these sites are more suitable for ticks and that aggregation may serve as protection from severe conditions. In contrast, a shift to a lower height was observed in H. longicornis nymphs and larvae when other species were present, suggesting that they were driven away by other species, especially H. megaspinosa. Heterospecific clusters composed of at least 2 species were formed on stem tips more frequently. It is concluded that questing site was affected by both aggregation pattern and the presence of other species.     

Bidirectional incompatibility among divergent Wolbachia and incompatibility level differences among closely related Wolbachia in Nasonia

Most insect groups harbor obligate bacterial symbionts from the alpha-proteobacterial genus Wolbachia. These bacteria alter insect reproduction in ways that enhance their cytoplasmic transmission. One of the most common alterations is cytoplasmic incompatibility (CI) - a post-fertilization modification of the paternal genome that renders embryos inviable or unable to complete diploid development in crosses between infected males and uninfected females or infected females harboring a different strain. The parasitic wasp species complex Nasonia (N. vitripennis, N. longicornis and N. giraulti) harbor at least six different Wolbachia that cause CI. Each species have double infections with a representative from both the A and B Wolbachia subgroups. CI relationships of the A and B Wolbachia of N. longicornis with those of N. giraulti and N. vitripennis are investigated here. We demonstrate that all pairwise crosses between the divergent A strains are bidirectionally incompatible. We were unable to characterize incompatibility between the B Wolbachia, but we establish that the B strain of N. longicornis induces no or very weak CI in comparison to the closely related B strain in N. giraulti that expresses complete CI. Taken together with previous studies, we show that independent acquisition of divergent A Wolbachia has resulted in three mutually incompatible strains, whereas codivergence of B Wolbachia in N. longicornis and N. giraulti is associated with differences in CI level. Understanding the diversity and evolution of new incompatibility strains will contribute to a fuller understanding of Wolbachia invasion dynamics and Wolbachia-assisted speciation in certain groups of insects.     

Monogeneans in introduced and native cichlids in México: evidence for transfer

We examined 2 cichlid fish species native to México, Cichlasoma callolepis and C. fenestratum, and 2 introduced African cichlids, Oreochromis aureus and O. niloticus, from 3 localities in southeastern México for monogeneans. Six monogenean species infected the African cichlids: Cichlidogyrus haplochromii, C. dossoui, C. longicornis longicornis, C. sclerosus, C. tilapiae, and Enterogyrus malmbergi. We found all these parasite species, except C. haplochromii and C. dossoui, on the native C. fenestratum and C. callolepis. Prevalences of Cichlidogyrus spp. were 3-10% and abundances ranged from 0.03 +/- 0.2 to 0.1 +/- 0.3 for native cichlids. We only recovered a single E. malmbergi from 1 C. callolepis. We found Sciadicleithrum bravohollisae, a monogenean of native Cichlasoma spp., on the gills of the introduced O. aureus from Lake Catemaco (prevalence 3%, abundance 0.03 +/- 0.2). Although prevalence and abundance in atypical hosts were fairly low, the present findings provide evidence of monogenean transfer from African to American cichlids and vice versa. This is the first record of exotic monogeneans in the genus Cichlidogyrus and Enterogyrus infecting native American cichlid fish. It is also the first record from southeastern México of a native American monogenean infecting introduced African cichlids.     

Molecular characterization of a troponin I-like protein from the hard tick Haemaphysalis longicornis.

A cDNA expression library prepared from mRNA of Haemaphysalis longicornis (H. longicornis) was screened with a H. longicornis-infested rabbit serum. A cDNA encoding 27/30kDa proteins was cloned and designated P27/30 gene. The predicted amino acid sequence of the P27/30 gene shows a rather high homology (58% amino acid identities and 11% amino acid similarity) with Drosophila melanogaster troponin I clone E2. H. longicornis P27/30 possesses amino acid sequence of actin-binding domains of troponin I at the amino acid residues 128-148, suggesting that H. longicornis P27/30 is a troponin I-like protein. By immunoblot analysis, mouse anti-recombinant P27/30 serum reacted with major constituent protein bands in extracts of adult ticks, and also immunoreacted with muscle, cuticle, gut, and salivary gland in H. longicornis ticks. Moreover, immunohistochemistry using the anti-P27/30 serum showed a strong reactivity in muscle, suggesting that native P27/30 is expressed abundantly in that tissue.     

Modeling fractal structure of city-size distributions using correlation functions

Zipf's law is one the most conspicuous empirical facts for cities, however, there is no convincing explanation for the scaling relation between rank and size and its scaling exponent. Using the idea from general fractals and scaling, I propose a dual competition hypothesis of city development to explain the value intervals and the special value, 1, of the power exponent. Zipf's law and Pareto's law can be mathematically transformed into one another, but represent different processes of urban evolution, respectively. Based on the Pareto distribution, a frequency correlation function can be constructed. By scaling analysis and multifractals spectrum, the parameter interval of Pareto exponent is derived as (0.5, 1]; Based on the Zipf distribution, a size correlation function can be built, and it is opposite to the first one. By the second correlation function and multifractals notion, the Pareto exponent interval is derived as [1, 2). Thus the process of urban evolution falls into two effects: one is the Pareto effect indicating city number increase (external complexity), and the other the Zipf effect indicating city size growth (internal complexity). Because of struggle of the two effects, the scaling exponent varies from 0.5 to 2; but if the two effects reach equilibrium with each other, the scaling exponent approaches 1. A series of mathematical experiments on hierarchical correlation are employed to verify the models and a conclusion can be drawn that if cities in a given region follow Zipf's law, the frequency and size correlations will follow the scaling law. This theory can be generalized to interpret the inverse power-law distributions in various fields of physical and social sciences.     

Climate change likely to reduce orchid bee abundance even in climatic suitable sites

Studies have tested whether model predictions based on species’ occurrence can predict the spatial pattern of population abundance. The relationship between predicted environmental suitability and population abundance varies in shape, strength and predictive power. However, little attention has been paid to the congruence in predictions of different models fed with occurrence or abundance data, in particular when comparing metrics of climate change impact. Here, we used the ecological niche modeling fit with presence–absence and abundance data of orchid bees to predict the effect of climate change on species and assembly level distribution patterns. In addition, we assessed whether predictions of presence–absence models can be used as a proxy to abundance patterns. We obtained georeferenced abundance data of orchid bees (Hymenoptera: Apidae: Euglossina) in the Brazilian Atlantic Forest. Sampling method consisted in attracting male orchid bees to baits of at least five different aromatic compounds and collecting the individuals with entomological nets or bait traps. We limited abundance data to those obtained by similar standard sampling protocol to avoid bias in abundance estimation. We used boosted regression trees to model ecological niches and project them into six climate models and two Representative Concentration Pathways. We found that models based on species occurrences worked as a proxy for changes in population abundance when the output of the models were continuous; results were very different when outputs were discretized to binary predictions. We found an overall trend of diminishing abundance in the future, but a clear retention of climatically suitable sites too. Furthermore, geographic distance to gained climatic suitable areas can be very short, although it embraces great variation. Changes in species richness and turnover would be concentrated in western and southern Atlantic Forest. Our findings offer support to the ongoing debate of suitability–abundance models and can be used to support spatial conservation prioritization schemes and species triage in Atlantic Forest.     

A Comparison of the Zooplankton in Two Newfoundland Bays with Differing Influences from Major Currents

Quantitative zooplankton samples were obtained at four regular stations and one irregular station in Placentia Bay, Newfoundland between mid June 1974 and mid May 1976. Sampling was attempted fortnightly as regularly as weather conditions and competition from other ship users would allow. The results are compared with those obtained and previously published in a similar study from Conception Bay, Newfoundland in 1977 to 1978. There was a greater diversity of species in Placentia Bay, and for most species the numbers/m³ were greater. The two bays are influenced by somewhat different current systems, and climatic conditions are a little milder and foggier in Placentia Bay. The same species were common in both bays, with copepods usually being the most important. Among copepods, two of the most important species namely Pseudocalanus sp. and Oithona similis were less abundant in Placentia Bay, but this was offset by a greater abundance of Temora longicornis. A few of the problems that require further investigation are outlined.     

Intermittency in the plankton: a multifractal analysis of zooplankton biomass variability

We present the first evidence that variability in zooplanktonbiomass can be characterized as a multifractal. An hourly tuneseries of vertically integrated acoustic biomass measurements,taken from a fixed mooring on the Atlantic coastline, providedthe data for our analysis. Two measures of variability wereanalyzed: the first difference squared and the squared differencefrom the mean. When integrated over time, these quantities provideestimates of biomass variability. The distribution in time ofthese measures of variability is highly intermittent. We showthat such intermittency is well described by the scaling propertiesof multifractals. In zooplankton ecology, potential applicationsof this analysis include comparing plankton variability distributionsto those of passive scalars and environmental variables, quantifyingspatial or temporal heterogeneity in intermittent quantities,and determining scales over which similar processes are operating. ¹Present address: University of Tel Aviv, Department of Zoology,Ramat Aviv, 69978 Tel Aviv, Israel     

Ant communities (Hymenoptera: Formicidae) in an urban ecosystem near the Atlantic Rainforest

The relationships between an urban ecosystem located near the Atlantic Rainforest in southeastern Brazil and ant communities were studied with the objective of quantifying the ant richness and abundance in the household environment and its surroundings. Eighty residences were sampled, where 58 species and 28 genera pertaining to 7 sub-families were found to be present. Inside the residences, the species richness was found to be lower (26), although the abundance was greater (10,670), with the wash area and kitchen being the locales that contributed with the greatest number of hits. The opposite was true in the areas outside the residences, where 54 species and 3,747 ants were observed. Inside houses, the species known as Tramp ants were found, in the following order of importance: Solenopsis saevissima, Tapinoma melanocephalum, Linepithema humile, Paratrechina fulva, Wasmannia auropunctata, P. longicornis, Pheidole megacephala, Monomorium pharaonis and M. floricola. Externally, mainly in the yards and gardens, species such as Octostruma rugifera, Heteroponera dolo, Hypoponera sp.1 and sp.6, Gnamptogenys sp. 4, G. striatula, Odontomachus meinerti, Pachycondyla constricta and P. striata were found. In general, a greater number of species and lower abundance of individuals were observed in the neighborhoods nearer the mountains than in those closer to the urban center.