The Hydrochemical and Physical Characteristics of the Breeding Sites of the Simulium neavei Roubaud Group and their Associated Crabs in the Eastern Usambara Mountains in Tanzania

Investigations on the hydrochemical and physical parameters of the breeding sites of Simulium woodi (an onchocerciasis vector). and Simulium nyasalandicum, and on their aquatic stages and associated crabs, were carried out for 13 months in the Zigi (Sigi). River system. The conductivity, pH and concentration of the main ions and silicate were all higher in the breeding sites of S. woodi than in those of S. nyasalandicum. S. woodi was restricted to small heavily shaded streams and did not enter rivers and large streams which contained higher concentrations of ammonium and nitrite. S. nyasalandicum was most numerous in rivers and large streams, but invaded small heavily shaded streams during the rainy season when conductivity and pH values were reduced.     

Bioremediation potential of three carrageenophytes cultivated in tanks with seawater from fish farms

Intensive fish farming discharges large amount of nutrients, the majority of which are composed of dissolved nitrogen in ammonium form, which promotes eutrophication in coastal waters. Macroalgae have been proven to effectively reduce the nutrients of fish farm effluents and at the same time increase the economic output of the aquaculture system when economically important species are utilized. In this study, the potential of three high value carrageenophytes (Kappaphycus alvarezii, Kappaphycus sp., K. striatum) to extract ammonium in fish farm effluent collected from a milkfish (Chanos chanos) fish cage was investigated. To establish economic viability of the integrated culture system, the effects of elevated total ammonia of fish farm effluent on the growth rate, phycocolloid content, and quality of these seaweeds were determined. Tank cultivation trials showed that the three carrageenophytes substantially reduced the ammonium content of the fish farm effluent (41–66% reduction efficiency) and consequently attained maximum daily growth rates of 4.41%, 2.90%, and 2.75% for K. striatum, Kappaphycus sp., and K. alvarezii, respectively. Their carrageenan content was improved. Carrageenan quality, however, was not significantly enhanced. Elevated ammonium in fish farm effluent did not adversely affect the performance of tank cultivated Kappaphycus; thus, future integration of these seaweeds in fish farms is feasible. Presented at the 6th Meeting of the Asian Pacific Society of Applied Phycology, Manila, Philippines.     

Effects of land use on black fly assemblages (Diptera: Simuliidae) in submontane rivers (West Carpathians, Slovakia)

The effects of land use on black fly assemblages were investigated in submontane rivers (the Ľubochnianka River, the Revúca River, upper Váh River catchment) in the Carpathians. We recorded 11 black fly species in the Ľubochnianka River and 10 species in the Revúca River. Land use differs between the catchments; the Ľubochnianka is a primarily forested catchment, and the Revúca is markedly deforested catchment. Fifteen environmental variables were analysed. Based on the results provided by CANOCO, phosphorus level and stream slope are the most important variables and have significant influences on the variability of black fly assemblages. In spring, Prosimulium rufipes occurred along the entire lengths of the streams. The black fly assemblage of the Revúca River differs from the assemblage of the Ľubochnianka River mainly by its higher abundances of Simulium variegatum and Simulium ornatum, by the presence of Simulium carthusiense, and by the absence of Prosimulium hirtipes.     

Are black flies of the subgenus Wilhelmia (Diptera: Simuliidae) multiple species or a single geographical generalist? Insights from the macrogenome

Organisms with vast distributions often represent geographical mosaics of cryptic species. The black fly Simulium (Wilhelmia) lineatum is among the most widely distributed members of the family Simuliidae, ranging from the British Isles to eastern China. Rather than viewing S. lineatum as a possible aggregate of multiple species, taxonomists have suggested a more inclusive taxon with additional synonyms. Accordingly, S. lineatum is an ideal candidate for testing the hypothesis that a wide geographical distribution signals the presence of more than one species. A cytogenetic approach was used to probe the macrogenome of S. lineatum and other taxa proposed by taxonomists as conspecific. The banding patterns in the polytene chromosomes of 480 larvae from 15 countries across the Palearctic Region revealed 128 rearrangements of the complement. All rearrangements were autosomal and 89% were inversions nonrandomly distributed among species and among chromosome arms. The analyses clarify long‐standing confusion over previously proposed names and reveal a longitudinal succession of four species sequentially replacing one another from west to east: Simulium lineatum s.s., Simulium balcanicum, Simulium turgaicum, and Simulium takahasii. Thus, S. turgaicum is recalled from synonymy and the other three species are validated. Within the most‐represented species, S. balcanicum, the frequency of inversions follows a longitudinal gradient with a north–south bias; as the distance between the sites increases along this north‐west–south‐east axis, the similarity of inversion frequencies between sites decreases. Validation of the concept that broadly distributed black flies are composites of structurally similar species provides a framework for guiding discovery of additional biodiversity. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 114 , 163–183.     

Competition between two stream dwelling filter-feeders,Hydropsyche oslari and Simulium virgatum

Summary This study investigated whether interspecific competition affected the abundance and distribution of Hydropsyche oslari and Simulium virgatum. In addition, I studied the mechanisms of competition between the two taxa. H. oslari was the superior competitor when compared to S. virgatum because the presence of H. oslari in boulder habitats in Refugio Creek altered the microdistribution and depressed numbers of S. virgatum. Hydropsyche preempted space and was aggressive towards Simulium. Simulium avoided both hydropsychid larvae and their nets. This avoidance behaviour was reinforced by aggression from H. oslari. Possible immediate reasons why simuliids avoided Hydropsyche nets included 1) Hydropsyche attacked Simulium, 2) occupied nets interfered with feeding through increased turbulence or lower renewal rate for food, and 3) Simulium preferred to settle with conspecifics.     

Seasonal and spatial variation in the diet of brown trout (Salmo trutta L.) in the subarctic River Laxá, north-east Iceland

This study examines seasonal and spatial patterns in the diet composition, stomach fullness and condition of a landlocked population of brown trout (2.5–61.3 cm) in the lake-fed River Laxá in NE-Iceland. The stomach contents consisted predominantly of benthic invertebrates, such as blackfly larvae Simulium vittatum (58%), chironomids (24%) and the freshwater snail Radix peregra (7%). The seasonal and spatial patterns of S. vittatum in the stomach contents were consistent with published studies on the life cycle and production of S. vittatum in the River Laxá. Close to the Lake Myvatn outlet (0–16 km), S. vittatum constituted 63% of the stomach content volume, and exhibited two peaks (i.e., generations) in its seasonal contribution to the stomach contents, whereas further downstream (16–35 km) S. vittatum constituted 45% of the volume and showed only clear evidence of one generation. Seasonal fluctuations in S. vittatum availability appear to affect the stomach fullness and the condition factor of the trout, especially close to the lake outlet where the fluctuations are pronounced.     

Emergence patterns and ecological associations of some haematophagous blackfly species along an oligotrophic hydrosystem

Emergence patterns of blackflies (Diptera: Simuliidae) were investigated for 2 years at nine sites in the Plitvice Lakes area of Croatia, using pyramid‐type traps. A total of 38 012 specimens representing 10 haematophagous species were collected. The dominant species was Simulium angustipes Edwards, 1915, a vector transmitting avian trypanosomes. Water temperature, alkalinity, conductivity and habitat type represented the factors with the greatest degree of influence on blackfly species composition, structure and distribution along a longitudinal gradient of this oligotrophic karstic hydrosystem. Simulium angustipes was highly associated with lake outlets. The blackfly communities at all sites were dominated by species typical of the rhithral zone, but there was a shift in species composition along a longitudinal gradient from the hypocrenal–epirhithral to the epirhithral–metarhithral zone. Multiple generations per year were detected in S. angustipes, whereas in Simulium costatum Friederichs, 1920, the number of generations differed between sites with constant and those with variable water temperature.     

A description of ammonium content of output waters from trout farms in relation to stocking density and flow rates

Daily levels of ammonium content in the outflow water of an intensive trout farm and of a mountain pond stocked with rainbow trout were monitored. Output water was sampled for 30 days and analysed every 30 min by an automatic ion selective electrode system (Applikon ADI 2013); input water was also monitored. The ammonium output level was influenced more by atmospheric events than nitrogen excretion by fish. Observed data confirmed an overall ammonium excretion model previously estimated in both laboratory and field conditions. The high water flow, that characterises the intensive trout farm where the observations were made induced a high dilution of metabolites. Consequently, if the peaks of ammonium output did not reach values of 0.35–0.40 mg l⁻¹ the environmental impact was limited and not easily detected. Our results allow us to affirm that the optimal level of water flow rate for effective zeolite-operated filtration is around 10.3 l t⁻¹ s⁻¹.     

Populations of ducks and trout of the River Laxá, Iceland, in relation to variation in food resources

We examined annual variation in production, recruitment and density of the three most abundant vertebrate species of the River Laxá at Lake Myvatn, Iceland: Barrow’s goldeneye, Bucephala islandica, harlequin duck, Histrionicus histrionicus, and brown trout, Salmo trutta, in relation to food resources and other environmental variables. The study is largely based on correlations from long-term monitoring series in the period 1975–2002. Production of young in the harlequin duck was significantly correlated with food resources (the blackfly, Simulium vittatum) of the river, as was the recruitment of brown trout to the angling stock. In Barrow’s goldeneye, which uses both the lake and the river, dispersion of adults in spring and young in August was influenced by the availability of aquatic insects in each habitat. The dispersion of Barrow’s goldeneye tracks the availability of aquatic insects in each of these two main habitats. Introduced Amercian mink, Mustela vison, may have affected spring numbers and dispersion of harlequin ducks, but the evidence was not conclusive. Numbers of both duck species and the trout (as CPUE) were relatively stable, although a sharp drop in numbers followed by slow recovery was observed in Barrow’s goldeneye, and an increase was observed in harlequin ducks in the first year of study.     

Development and evaluation of methods to assess populations of black flies (Diptera: Simuliidae) at nests of the endangered whooping crane (Grus americana)

Hematophagous insects can negatively affect the reproductive success of their vertebrate hosts. To determine the influence of hematophagous insects on endangered vertebrates requires specially designed programs that minimize disturbance to the hosts and address problems associated with their small populations. We developed and evaluated a surveillance program for black flies potentially affecting a population of whooping cranes (Grus americana) introduced to central Wisconsin, U.S.A. In one of the few studies to survey host‐seeking female black flies and their immature stages concurrently, we processed nearly 346,000 specimens and documented 26 species, of which only two, Simulium annulus and Simulium johannseni, were attracted to nesting whooping cranes. Attempts to assess black fly populations with artificial nests and real crane eggs were unsuccessful. Carbon‐dioxide traps performed well in describing black fly taxa on the landscape. However, the number of black flies at whooping crane nests was consistently higher than the number captured in carbon‐dioxide traps. The carbon‐dioxide traps poorly described the presence/absence, population fluctuations, and periodicity of black flies at whooping crane nests. The weak performance of the carbon‐dioxide traps might have resulted from microhabitat differences between trap locations and nests or from Simulium annulus and Simulium johannseni using sensory cues in addition to carbon dioxide to find hosts. Choice of trapping techniques, therefore, depends on the information required for the particular study objectives.     

Black spot infection in juvenile steelhead trout increases with stream temperature in northern California

Climate change will increase water temperature in rivers and streams that provide critical habitat for imperiled species. Warmer water temperatures will influence the intensity and nature of biotic interactions, including parasitism. To better understand the factors influencing a neascus-type parasitic infection known as black spot disease, we examined the relationship between infection rate in juvenile steelhead trout (Oncorhynchus mykiss), abundance of another intermediate host (ramshorn snail, Planorbella trivolvis), and water temperature. We quantified infection patterns of trout at seven sites within the South Fork Eel River in northern California, visiting each site on three different occasions across the summer, and recording water temperature at each site. We also quantified infection patterns in trout captured from two tributaries to the South Fork Eel River. Overall, trout infection rates were highest in sites with the warmest temperatures. The abundance of ramshorn snails was positively related to both water temperature and black spot infection rates in juvenile trout. Both snail abundance and infection rates increased rapidly above a 23 °C daily maximum, suggesting a threshold effect at this temperature. We suggest that warmer temperatures are associated with environmental and biotic conditions that increase black spot disease prevalence in threatened steelhead trout. A comparison of our results with similar data collected from a more northern latitude suggests that salmonids in California may be warm-adapted in terms of their parasite susceptibility.     

The Simulium vernum group (Diptera: Simuliidae) in Europe: multiple character sets for assessing species status

The value of using characters from multiple sources – chromosomes, ecology, gene sequences, and morphology – to evaluate the species status of closely related black flies is demonstrated for three European members of the Simulium vernum group: Simulium crenobium (Knoz, 1961), Simulium juxtacrenobium Bass & Brockhouse, 1990, and Simulium vernum s.s. Macquart, 1826. Simulium juxtacrenobium is a chromosomally, molecularly, and morphologically distinct species that diverged from S. crenobium and S. vernum s.s. about 2 Mya. It is specialized for intermittent streams, is univoltine, and is recorded for the first time from northern Europe, based on collections from Finland and Sweden, representing a range extension of about 1800 km. In contrast, S. crenobium, although confirmed as a distinct species, differs from S. vernum s.s. by only a few larval and chromosomal characters, and by a breeding habitat restricted to mountain spring brooks. Whereas all four character sets independently support the specific distinctness of S. juxtacrenobium and S. vernum s.s., multiple character sets are required to establish the specific validity of S. crenobium.     

Cues used by the black fly,Simulium annulus,for attraction to the common loon (Gavia immer)

The parasitic relationship between a black fly, Simulium annulus, and the common loon (Gavia immer) has been considered one of the most exclusive relationships between any host species and a black fly species. To test the host specificity of this blood‐feeding insect, we made a series of bird decoy presentations to black flies on loon‐inhabited lakes in northern Wisconsin, U.S.A. To examine the importance of chemical and visual cues for black fly detection of and attraction to hosts, we made decoy presentations with and without chemical cues. Flies attracted to the decoys were collected, identified to species, and quantified. Results showed that S. annulus had a strong preference for common loon visual and chemical cues, although visual cues from Canada geese (Branta canadensis) and mallards (Anas platyrynchos) did attract some flies in significantly smaller numbers.     

Trout induces a shift from preferred habitat types for indigenous species: the example of the indigenous catfish, <Emphasis Type="Italic">Amphilius uranoscopus</Emphasis> (Pfeffer, 1889), on an African montane plateau

This study investigated the impact of introduced rainbow trout, Oncorhynchus mykiss, on the distribution and feeding of mountain catfish, Amphilius uranoscopus, on the Nyika Plateau, Malawi. Twenty-four sites were sampled over three different periods in three rivers. Fish habitat units were identified as separate riffle or pool, about 100 m in length, at each site. Each habitat unit was sampled for fish, invertebrates and physical habitat characteristics. Twenty four and 20 habitat units were sampled, respectively, from sites with catfish and sites with trout and catfish. In the absence of trout, the mountain catfish was associated with all depth ranges, with strong preference to shallow and moderate depth, and moderate to fast flow on coarse substratum type (gravel, pebble and boulder). In the presence of trout, the catfish was frequently associated with very shallow depth and slow flow. In its natural habitat, the catfish fed randomly, but preferred the most abundant invertebrate taxa, especially black fly larvae (Simuliidae). In the presence of trout, the catfish preferred mostly the chironomids. The preference by catfish for Simuliidae, also preferred by trout, was less in the trout streams than in its natural habitat. The prey taxa in the catfish stream were diverse, and consisted of large invertebrate predators. Trout streams were dominated by few prey taxa, especially black flies and chironomids. The catfish of the Nyika Plateau may represent genetically unique populations in southern Africa. Introductions of trout into rivers where they currently do not occur on the Nyika should be prevented in order to maintain the genetic diversity of the Amphilius uranoscopus species complex. Handling editor: J. A. Cambray     

Dietary adjustability of grizzly bears and American black bears in Yellowstone National Park

Grizzly bears (Ursus arctos) and American black bears (U. americanus) are sympatric in much of Yellowstone National Park. Three primary bear foods, cutthroat trout (Oncorhynchus clarki), whitebark pine (Pinus albicaulis) nuts, and elk (Cervus elaphus), have declined in recent years. Because park managers and the public are concerned about the impact created by reductions in these foods, we quantified bear diets to determine how bears living near Yellowstone Lake are adjusting. We estimated diets using: 1) stable isotope and mercury analyses of hair samples collected from captured bears and from hair collection sites established along cutthroat trout spawning streams and 2) visits to recent locations occupied by bears wearing Global Positioning System collars to identify signs of feeding behavior and to collect scats for macroscopic identification of residues. Approximately 45 ± 22% ( ± SD) of the assimilated nitrogen consumed by male grizzly bears, 38 ± 20% by female grizzly bears, and 23 ± 7% by male and female black bears came from animal matter. These assimilated dietary proportions for female grizzly bears were the same as 10 years earlier in the Lake area and 30 years earlier in the Greater Yellowstone Ecosystem. However, the proportion of meat in the assimilated diet of male grizzly bears decreased over both time frames. The estimated biomass of cutthroat trout consumed by grizzly bears and black bears declined 70% and 95%, respectively, in the decade between 1997–2000 and 2007–2009. Grizzly bears killed an elk calf every 4.3 ± 2.7 days and black bears every 8.0 ± 4.0 days during June. Elk accounted for 84% of all ungulates consumed by both bear species. Whitebark pine nuts continue to be a primary food source for both grizzly bears and black bears when abundant, but are replaced by false-truffles (Rhizopogon spp.) in the diets of female grizzly bears and black bears when nut crops are minimal. Thus, both grizzly bears and black bears continue to adjust to changing resources, with larger grizzly bears continuing to occupy a more carnivorous niche than the smaller, more herbivorous black bear. © 2012 The Wildlife Society.     

A survey of black scale,Saissetia oleae [Hom.: Coccidae] parasitoids [Hym.: Chalcidoidea] in southern California

A survey of black scaleSaissetia oleae (Olivier) parasitoids present in southern California was conducted between September 1987 and September 1989. From 308 collections of black scale-infested citrus, olive, and oleander twigs from 19 sites in southern California, 1,610 specimens were collected. Nine primary and six secondary parasitoid species were identified. Four primary species were abundant in southern California:Metaphycus bartletti Annecke & Mynhardt,M. helvolus (Compere),Scutellista caerulea (Fonscolombe) (=S. cyanea Motschulsky), andDiversinervus elegans Silvestri. The most common secondary parasitoids wereMarietta mexicana (Howard),Cheiloneurus noxius Compere, andTetrastichus minutus (Howard). In the coastal region of southern California,M. bartletti was the most abundant parasitoid, followed in order byD. elegans, S. Caerulea, andM. helvolus. In the intermediate and interior regions,M. helvolus was most abundant.D. elegans was second most abundant in the intermediate region, but was rare in the interior region.M. bartletti was second in abundance in the interior region and third in the intermediate region.      

Effect of organic and inorganic nitrogen sources on endogenous polyamines and growth of ectomycorrhizal fungi in pure culture

 The abilities of three ectomycorrhizal fungi, Paxillus involutus, Suillus variegatus and Lactarius rufus, to utilize organic and inorganic nitrogen sources were determined by measuring the growth and endogenous free polyamines (putrescine, spermidine and spermine) of pure culture mycelium. Differences were found in the utilization of the nitrogen sources and in the polyamine concentrations between the fungal species and between isolates of L. rufus. All the fungi grew well on ammonium and on several amino acids. Endogenous polyamine levels varied with the nitrogen source. Spermidine was commonly the most abundant polyamine; however, more putrescine than spermidine was found in P. involutus growing on inorganic nitrogen or arginine. Low amounts of spermine were found in S. variegatus and some samples of L. rufus. None or only a trace of spermine was found in P. involutus mycelium. In all fungi, putrescine concentrations were higher with ammonium than with the nitrate treatment. The total nitrogen content of peat did not determine the ability of L. rufus strains isolated from peatland forest sites to utilize organic nitrogen. Accepted: 27 November 1998     

Molecular circumscription of the blackfly Simulium oyapockense from South America

Problems related to the identity of Simuliidae species are impediments to effective disease control in Amazonia. Some of these species, such as Simulium oyapockense Floch & Abonnenc, 1946 (Diptera: Simuliidae), are vectors of the organisms that cause onchocerciasis and mansonellosis diseases. This blackfly species has a wide distribution in South America, and it is suspected of being a complex of cryptic species. The aim of this study is to characterize the nominal species S. oyapockense using partial COI gene sequences. Seven populations of S. oyapockense (morphologically identified) were analysed, including one from its type-locality. The other six populations were collected in Brazil and in Argentina. A taxon collected in Amazonas state, Brazil, with adults similar to S. oyapockense but with distinct pupae, was also included in the analysis (Simulium ‘S’). The nominal species S. oyapockense is circumscribed, and its geographical distribution is restricted to areas north of the Amazon River. Populations of S. oyapockense s.l. collected south of the Amazon River comprise a species complex that needs to be evaluated using integrative taxonomy. Simulium ‘S’ represents a species with unique morphological and molecular characteristics. Distinguishing cryptic species is a prerequisite for reducing the taxonomic impediment, especially in medically important taxa.     

Assessing trout farm pollution by biological metrics and indices based on aquatic macrophytes and benthic macroinvertebrates: A case study

In this study we examine the ecological responses of aquatic macrophytes and benthic macroinvertebrates to a trout farm effluent located in the upper Tajuña River (Guadalajara province, Central Spain), comparing the suitability of biological metrics and indices based on these two communities to assess trout farm pollution in the upper reaches of fluvial ecosystems. Sampling surveys were carried out in winter and summer 2006, and in spring 2007. Four sampling sites were selected along the study reach: S-1, placed upstream from the trout farm, was used as a reference station; S-2, S-3 and S-4 were placed about 10, 100 and 1000 m downstream from the trout farm outlet, respectively. The stream bottom was mainly stony with cobbles and pebbles at all sampling sites, except at S-2 where it was covered by a thick layer of organic sediment. Aquatic macrophytes and benthic macroinvertebrates significantly increased in abundance downstream from the trout farm effluent, particularly at S-3 and S-4. However, while the diversity of aquatic macrophytes increased downstream (at S-3 and S-4, but not at S-2), the diversity of benthic macroinvertebrates significantly decreased, particularly at S-2. Regarding aquatic macrophytes, moss coverage values, as well as values of the Index of Macrophytes (IM) and the Macroscopic Aquatic Vegetation Index (MAVI), were higher at S-1 than at S-2. In contrast, values of moss coverage and IM were significantly lower at S-1 than at S-3 and S-4. MAVI values were similar at S-1, S-3 and S-4. Regarding benthic macroinvertebrates, the abundance percentage of oligochaetes and chironomids (expressed as OC%) was significantly higher at downstream polluted sites (particularly at S-2) than at S-1. Conversely, the abundance percentage of ephemeropterans, plecopterans and trichopterans (expressed as EPT%), and scores of the total Biological Monitoring Water Quality (t-BMWQ) index and the average Biological Monitoring Water Quality (a-BMWQ) index were much lower at S-2 than at S-1, with a clear tendency to increase with increasing downstream distance from the trout farm. Correlation analyses showed that changes in physicochemical parameters (inorganic nutrients, dissolved oxygen and turbidity) along the study reach were better correlated with changes in metrics and indices based on benthic macroinvertebrates. Overall it is concluded that metrics and indices based on benthic macroinvertebrates (such as OC% and EPT% metrics and t-BMWQ and a-BMWQ indices) can be more suitable than those based on aquatic macrophytes for the biological monitoring of trout farm pollution in the upper reaches of fluvial ecosystems, since the higher diversity of benthic macroinvertebrates inhabiting the river bottom would permit this community to exhibit a better indicator performance regarding the environmental stress caused by trout farm effluents. However, further studies are needed in order to generalize this conclusion.     

Contribution to the knowledge of the black‐fly fauna (Diptera: Simuliidae) of Lebanon,with description of a new species and ecological comments

The Aouali and Damour watersheds include the main river systems of southern Lebanon. Seven species of Simuliidae were collected from 27 sampling stations along these streams. Simulium nihan. sp. is described; it is related to the species of the monticola‐group. Three species have a restricted distribution within these streams, two of them being crenobiont. The others extend over wide altitudinal and ecological ranges. Eusimulium latizonum, Wilhelmia pseudequina and Simulium nitidifrons are the dominant species of the black‐fly community.