Spatial and size-frequency distribution of <Emphasis Type="Italic">Acropora</Emphasis> (Cnidaria: Scleractinia) species in Chinchorro Bank,Mexican Caribbean: implications for management

The Mexican Government decreed Chinchorro Bank reef as a Biosphere Reserve in 1996. The aim of this study was to evaluate the spatial and size-frequency distribution of Acropora spp. in order to provide further knowledge and tools to enhance management. A field survey was conducted, within six regions, to locate and measure Acropora patches in the reef lagoon. Density, colony size and living tissue cover of Acropora colonies were evaluated using the line-intercept transect technique, combining direct observations and video transects. The results showed that Acropora spp. was preferentially distributed in the southern regions; where cover and density were high. Based on these results and considering that Acropora spp. produces landscape heterogeneity, which in turn generates shelter for other species, including some of considerable economic importance, then at least the South East region should be considered as a key area for Acropora species conservation, and should be included in the Chinchorro Bank management plan.     

Comparison of autumn and spring migration strategies of Neotropical migratory landbirds in northeast Belize

ABSTRACT Migration represents one of the most vulnerable stages of a migrant's life cycle, but the strategies and stopover sites used by Neotropical migrants in Central America are not well known. We carried out constant‐effort mist netting and conducted censuses along transects during one autumn (2007) and one spring (2008) migration in northeast Belize. We recorded more landbird migrant species in autumn (63) than in spring (54), and spring abundance was >25% lower for 88% of transient species. These differences in presence and abundance indicate that routes and stopover strategies vary between seasons and species. In autumn, fuel loads, calculated as any increase in mass above lean body mass (LBM), were generally small (mean = 5.9% LBM and 10.1% LBM for wintering and transient species, respectively) and fuel deposition rates and minimum stopover durations suggest that some individuals replenished energy reserves in our study area. Variation in autumn fuel loads meant that some individuals had reserves sufficient for flights >1000 km. Fuel loads were larger in spring for 16 of 17 species, and the mean spring fuel load for transient species (32.5% LBM) was sufficient for a flight from northeast Belize to North America without refueling. The similarity in spring passage times between northeast Belize and the Gulf Coast of the United States also suggests that energy reserves were not replenished in northeast Belize prior to crossing the Gulf of Mexico. We hypothesize that sufficient energy reserves are accumulated during spring stopovers in northern South America or elsewhere in Mesoamerica to allow migrants to fly directly to North America without refueling.     

Spatial distribution and seasonality of ichthyoplankton and anthropogenic debris in a river delta in the Caribbean Sea

Temporal changes in larval fish species composition and abundance compared with other components of the seston are described in four estuarine habitats in the Atrato Delta, Colombia. In comparison with zooplankton, fish larvae and egg density and anthropogenic debris abundance were low in the South Atrato Delta. Transparency, water temperature and chlorophyll a were the major factors influencing the spatiotemporal distribution of ichthyoplankton in the delta. The most abundant fish larvae were Astyanax sp. 1, Anchovia clupeoides, Cetengraulis edentulus, Anchoa sp., Bathygbius curacao, Dormitator maculatus, Hyporhamphus sp., Atherinella blackburni, Gobiosoma sp. 1 and Menticirrhus americanus (92·8% of total abundance). Spatial temporal analysis shows that in this delta, shrub (arracachal) and grass (eneal) habitats are important for freshwater and estuarine species, whilst mudflat and mangrove are important for estuarine species and estuarine–marine species, since most flexion and post‐flexion stages of these species were found there. Anthropogenic debris density never surpassed the total ichthyoplankton density, but was ubiquitous. Shrub and mangrove habitats had higher densities of anthropogenic debris, since these are flood‐stem habitats that trap solids.     

Gelatinous invertebrate zooplankton of the South Adriatic: species composition and vertical distribution

The species composition and vertical distribution of gelatinousinvertebrate zooplankton were investigated from April 1993 toJune 1994 in the 0–1000 m water column at a deep-sea stationin the northern part of the South Adriatic Pit. Fifty-sevenspecies were identified: 11 hydromedusae, 13 calycophores, 3ctenophores, 3 heteropods, 10 pteropods, 8 polychaetes and 9chaetognaths. The pteropod Desmopterus papilio and the heteropodProtatlanta mediterranea were recorded for the first time inthe Adriatic Sea. Data from this study differed from those ofprevious investigations in the South Adriatic as regards thenumerically dominant polychaete and pteropod species. All investigatedgroups generally were more abundant in the upper 100 m and decreasedwith depth. Different vertical distributions of life stageswere observed for those species that occupy a wide depth range:Persa incolorata, Solmissus albescens, Limacina inflata, Cymbuliaperoni, Pelagobia longicirrata, Sagitta lyra and Sagitta decipiens.     

Abundance and distribution of hydroids in a mangrove ecosystem at Twin Cays,Belize, Central America

Qualitative and quantitative collecting was undertaken in 1987 to determine the species composition, abundance, and distribution of hydroids in a mangrove system at Twin Cays, Belize. Of 49 species identified, the 5 most frequent were Ventromma halecioides, Nemalecium sp., Clytia hemisphaerica, Dynamena crisioides and Halopteris diaphana. Line-transect census data and qualitative observations showed that the hydroid fauna was sparse in sheltered, still-water areas of the mangal, but relatively abundant and diverse in areas exposed to waves and/or tidal currents. Species composition and relative abundance varied with depth at stations in exposed locations and in tidal creeks and channels. Although Turritopsoides brehmeri is known only from Twin Cays at present, it seems improbable that any of the species is restricted to mangrove ecosystems.     

Helminth parasites of the tropical gar, Atractosteus tropicus Gill, from Tabasco, Mexico

A total of 8 helminth species were recorded in an examination of 43 tropical gar, Atractosteus tropicus Gill, collected at the Pantanos de Centla Biosphere Reserve, Tabasco, Mexico. The parasite species included 1 adult trematode, 3 metacercariae, 1 cestode, 1 adult nematode, and 2 nematode larvae. Six of these 8 species were rare, with low prevalence (< 17%) and abundance (< 1.0 helminths per examined fish). The larvae of Contracaecum sp. were the most abundant in the sample, constituting 60% of the total helminths (64% prevalence, 3.8 +/- 5.2 abundance), followed by the cestode Proteocephalus singularis, constituting 18% of the worms (30.5% prevalence, 1.1 +/- 3.0 abundance). Species richness, individual parasite abundance, and diversity were low in the infracommunities. The recording of 3 specialist species in the tropical gar confirms that the helminth fauna of gar has an appreciable degree of specificity. This study indicates the importance of ecological determinants of richness in helminth communities of the tropical gar.     

东海表层沉积中的翼足类及其地质意义

对东海84个表层沉积中翼足类进行了定量分析,共获得7属15种,其中Limacinainflata在陆架外缘和上陆坡为优势种,Limacinatrochi formis,Creseisacicula和Creseis virgule在中外陆架最为丰富。根据翼足类的深度分布确定东海现代文石补偿深度在约600m水深处。以冲绳海槽北部柱状样B3GC为例,说明翼足类是研究地质时期古海洋学变化的重要证据。     

Geographical and temporal variation in the diet of Bank Cormorants Phalacrocorax neglectus in South Africa

The Bank Cormorant Phalacrocorax neglectus is endemic to the Benguela upwelling ecosystem off southwest Africa and is classified as Endangered owing to a recent large reduction in its number. It is thought that food scarcity, including a decreased abundance of West Coast rock lobster Jasus lalandii, has been a major driver of the decrease, yet its diet in South Africa is poorly known. We collected 941 pellets regurgitated by Bank Cormorants, at 18 South African breeding colonies during 1975–1985, and 1 523 pellets at 17 colonies during 1995–2002. The species composition of the diet (% numbers) was significantly different between the two periods, with widespread decreases in proportions of rock lobster in the west and of octopus and cuttlefish Sepia spp. at most localities. These taxa were replaced in the diet by fish, including Gobiidae and Clinidae. The pelagic goby Sufflogobius bibarbatus, an important prey of Bank Cormorants in Namibia, was absent from pellets collected in 1975–1985 but common at northern localities from 1995–2002. Composition of the diet by frequency of occurrence was only determined for 1995–2002, when rock lobster was present in 67% of all samples collected, cuttlefish in 39%, and Clinidae in 32%. Data for 1975–1985 and 1995–2002 showed that carapace lengths of rock lobsters eaten by Bank Cormorants averaged 56 mm (range 22–82 mm) and 50 mm (range 22–75 mm), respectively, which compares to the minimum legal size of 75 mm for fisheries in South Africa. This energy- rich prey item was an important constituent of the diet in the winter breeding period.     

Parasitism of Hylodes phyllodes (Anura: Cycloramphidae) by Hannemania sp (Acari: Trombicuudae) in an area of Atlantic Forest, Ilha Grande, southeastern Brazil

We studied some parameters of the parasitism by the mite Hannemonia sp. on the endemic frog Hylodes phyllodes in the Atlantic Forest of Ilha Grande (Rio de Janeiro State, Brazil). Prevalence, mean abundance, mean intensity and total intensity of infestation, body regions infected, and host sexual differences in parasitism rate of the larvae of Hannemania sp. on individuals of H. phyllodes were assessed. Prevalence was 86.5% (N = 37; total of 1,745 larvae of Hannemania sp) for male hosts and 91.7% (N = 12; total of 330 larvae) for female hosts, with no significant difference between the sexes. Overall prevalence of Hannemania sp. on H. phyllodes was 87.7%. Mean intensity of infestation in males (54.5 +/- 42.5; range 1-173 larvae) was higher than in females (29.9 +/- 47.6; range 1-166). We conclude that the rates of intensity, abundance, and prevalence of Hannemania larvae parasitizing Hylodes phyllodes at Ilha Grande were considerably high, suggesting that this species of anuran constitutes a relevant host for this mite species to complete its life-cycle in the area. Differences between males and females in infestation rates probably reflect their differential use of space in the forest.     

A remarkable new species of Stephensia Stainton (Insecta: Lepidoptera: Elachistidae) from Belize rainforest (Central America)

Stephensia armata sp. n., a remarkable species is described from Belize (Central America). The external features and genitalia of the male are figured and described in detail. A distribution map for all six Elachistidae species, currently recorded from tropical America, is given: Perittia smaragdophanes (Meyrick), P. punatensis Kaila, Elachista albisquamella Zeller, E. saccharella (Busck), E. vasrana Kaila and Stephensia armata Sruoga, sp. n.     

Structure and grazing impact of the mesozooplankton community during late summer 1994 near South Georgia, Antarctica

Mesozooplankton abundance, community structure and grazing impact were determined during late austral summer (February/March) 1994 at eight oceanic stations near South Georgia using samples collected with a Bongo and WP-2 nets in the upper 200-m and 100-m layer, respectively. The zooplankton abundance was generally dominated by copepodite stages C3–C5 of six copepod species: Rhincalanus gigas, Calanus simillimus, Calanoides acutus, Metridia spp., Clausocalanus laticeps and Ctenocalanus vanus. Most copepods had large lipid sacs. All copepods accounted for 41–98% of total zooplankton abundance. Juvenile euphausiids were the second most important component contributing between 1 and 20% of total abundance. Pteropods, mainly Limacina inflata, were important members of the pelagic community at two sites, accounting for 44 and 53% of total abundance. Average mesozooplankton biomass in the upper 200 m was 8.0 g dry weight m⁻², ranging from 4.3 to 11.5 g dry weight m⁻². With the exception of Calanussimillimus, gut pigment contents and feeding activity of copepod species were low, suggesting that some species, after having stored large lipid reserves, had probably started undergoing developmental arrest. Daily mesozooplankton grazing impact, measured using in situ gut fluorescence techniques and in vitro incubations, varied widely from <1 to 8% (mean 3.5%) of phytoplankton standing stock, and from 5 to 102% (mean 36%) of primary production. The highest grazing impact was found northeast of the island co-incident with the lowest phytoplankton biomass and primary production levels. Received: 30 October 1996 / Accepted: 23 February 1997     

Spatial and temporal fluctuations in presence and use of chironomid prey by shorebirds in the Odiel saltpans, south-west Spain

We studied the seasonal variation in abundance and distribution of shorebirds and chironomid Chironomus salinarius larvae in both traditional and industrial salines in the Odiel marshes, south-west Spain, in 2001. We selected 12 ponds that were representative of the different phases of the salt production process. The benthic chironomids were sampled in each pond every 2 months, and the birds were counted weekly. Chironomid larvae were most abundant in spring and autumn, and in the ponds of lower salinity. The density of larvae averaged 7023 ± 392 m⁻² (±SE) over the six sampling events. Shorebirds were always more abundant at high tide than at low tide, and were especially abundant during the spring and autumn migration periods when up to 20,775 birds were counted. A total of 24 species were recorded, six of which were present in internationally important numbers. The salines were especially important as foraging and roosting habitat during migration. The percentage of birds that were feeding in the ponds was positively correlated with the abundance of chironomid larvae at accessible depths. The number of feeding birds was also higher in ponds with more chironomid larvae available. Despite more intensive management, industrial salines held higher densities of birds and a similar abundance of chironomids when compared with traditional salines.     

Winter spatial distribution of fish larvae assemblages relative to the hydrography of the waters surrounding Taiwan

The aim of this study was to investigate the species composition and distribution of fish larvae in relation to hydrographic conditions in the waters surrounding Taiwan Island (TI) in February 2003. In total, 242 kinds of fish larvae belonging to 127 genera and 75 families were recognized. Among these, 109 taxa were identified to the family or genus level, others to the species level. The 12 predominant types, which constituted 71% of the total fish larvae, were Engraulis japonica, Scomber sp., Diaphus spp., Benthosema pterotum, Carangoides ferdau, Embolichthys mitsukurii, Maurolicus sp., unidentified Myctophidae, Gonostoma gracile, Trichiurus lepturus, unidentified Gobiidae, and Myctophum asperum. The distribution of fish larvae showed a clear association with water masses around TI, with higher abundances and lower species richness northwest of TI where the China Coastal Current prevails, and lower abundances and higher species diversity east of TI where the Kuroshio Current dominates. Cluster analysis distinguished three station groups and four species groups, and the distribution patterns of fish larvae also corresponded to hydrographic conditions. The total abundances of fish larvae and eight of the 12 predominant taxa showed significant and positive correlations with zooplankton abundance, which suggests that food source might be a key factor determining the abundance and distribution of fish larvae during the winter.     

Rugiloricus bacatus sp. nov. (Loricifera ‐Pliciloricidae) and a ghost‐larva with paedogenetic reproduction

Abstract

A new species of Loricifera, Rugiloricus bacatus sp. nov. is described together with the diagnoses of two other Rugiloricus species, Rugiloricus sp. nov. A and B, from the Faroe Bank (North Atlantic). Characteristic for all three species is the presence of a new type of reduced larva, a ghost‐larva. This type of reduced larva was discovered in 1986 by Jeanne Renaud‐Mornant, but it was with the Faroe Bank material that it was first discovered that the ghost‐larvae belonged to the phylum Loricifera. The ghost‐larvae are eitherfound inside late instar Higgins‐larvae, called penultimate Higgins‐larvae, or in the sediment. The three types of Higgins‐larvae from the Faroe Bank can be distinguished by characters such as anterior setae, posterior setae and toes. The adults of Rugiloricus bacatus sp. nov. are characterised by a prominent ruff resembling a pearl necklace; two of the eight clavoscalids are modified in the 1st row; the 2nd row of leg‐shaped scalids are very large and robust, and the 9th row with 30 beak‐like scalids alternating with 30 alternating plates. The postlarvae are free‐living and their scalids on the introvert are reduced to protoscalids. Postlarvae and adult stages have not been found for Rugiloricus sp. nov. A and B and therefore only diagnoses of these two species are presented here.     

Cephalopods in the diet of the South African fur seal (Arctocephalus pusillus pusillus)

The stomach contents of 1522 adult seals ( Arctocephalus pusillus pusillus ) and 673 pups, which were collected around the West and South Coasts of Southern Africa, were examined and cephalopod prey identified. About 20 cephalopod species (some identifications were uncertain) were found in the stomachs, of which only six were significant: Loligo vulgaris reynaudii. Sepia spp., Octopus sp., Todaropsis eblanae, Todarodes angolensis and Ocythoe tuberculata. This list suggests that A. pusillus feeds exclusively on the continental shelf, frequently on or near the bottom. Among adults, cephalopod prey varied in importance around the coast. It was most important on the South Coast of South Africa where it comprised 35.0% of the weight of all prey, of which L. v. veynaudii constituted about 88%. On the West Coast cephalopods comprised about 26.6% by weight of all prey, and Octopus sp. predominated, whereas in Namibian waters cephalopods were least important, constituting only 3.4% by weight of all prey, with Todarodes angolensis and Octopus sp. being most significant. Among pups (aged 8–10 months) in the Lüderitz (Namibia) area, cephalopods were about 16.9% of prey by weight, of which Ocythoe tuberculata , small Sepia spp. and Octopoda were most important.     

Species composition, seasonal dynamics and numerical responses of arthropod predators in organic strawberry fields

The species composition and relative abundance of predatory arthropod fauna were studied in organic strawberry fields in northwestern Turkey using sweep net sampling and pitfall trapping (activity density). Arachnida constituted 13.1 and 11.5% of the sweep net and pitfall trap catches, respectively. Among the predatory insects, the most abundant groups were Heteroptera (26.7%), Diptera (25.9%), Coleoptera (16.9%) and Orthoptera (10.8%) in sweep net samples. Coleoptera (84.2%) dominated the pitfall trap catches. Many aphid specific and polyphagous predators reached peak abundance during June and July. Pearson's two-tailed correlations showed a significant and positive relationship between syrphid, coccinellid or chrysopid predator numbers and strawberry aphid density. Aphid density was not significantly correlated with carabid or with nabid abundance. Examination of spatial distribution patterns of all predatory arthropod groups using Taylor's Power Law indicated that most arthropod predators, except carabids, exhibited aggregated dispersion patterns. Coccinellids changed their spatial patterns from a uniform to an aggregated distribution through the season. There was also a significant linear correlation between Anterastes sp. abundance (larvae+adults) and Isophya rectipennis+Poecilimon ricteri (larvae+adults) density at both locations. We observed, for the first time, Anterastes preying on Isophya and Poecilimon species. The seasonal abundance of the major predatory groups were described, and their potential importance in controlling strawberry aphid and other pests is discussed.     

Changes in plankton and fish larvae communities across hydrographic fronts off West Greenland

The variability in plankton community structure was studiedin Disko Bay and across important fishing banks off the westcoast of Greenland. The primary goal of the study was to investigatepossible linkages between hydrographical processes and planktonstructures, hypothesizing that hydrographic fronts would bepresent in the area, and that these to a large extent determineplankton distribution, composition and productivity. We sampledalong four cross-shelf transects, one covering Disko Bay andDisko Bank, while the other three covered Store Hellefiske Bank,Lille Hellefiske Bank and Sukkertop Bank. The hydrography wasexamined by CTD profiling, the phytoplankton by fluorescenceprofiling and water bottle sampling, while mesozooplankton andichthyoplankton were sampled by vertical or oblique net hauls,respectively. We observed distinct along-shelf flowing currentsin the area (e.g. the West Greenland Current, the Polar Currentand the Irminger Current), and the physical characteristicsindicated frontogenesis at the shelf slope, in regions of 80–100m water depth. Phytoplankton and ichthyoplankton showed a cross-shelfstructuring with apparent linkages to frontal characteristics,while a more diverse pattern was observed for the mesozooplanktonwhich were dominated by Calanus finmarchicus, Calanus glacialisand Calanus hyperboreus. The relationship between hydrographiccharacteristics and plankton distribution differed among species,and apparently specific plankton communities were establishedin different areas of the shelf. For example the larvae of Boreogadussaida, Ammodytes sp., Reinhardtius hippoglossoides and Stichaeuspunctatus differed markedly in distributional characteristics.In addition to the cross-shelf structuring, marked differencesin species composition and total plankton abundance were observedin the along-shelf (north–south) direction. The latitudinaldifferences in the unicellular plankton communities are interpretedlargely within a seasonal successional framework (i.e. an earlydominance of diatoms followed by increasing importance of smallerunicellular plankton), while the ichthyo- and zooplankton communitiesalso differed by the respective dominance of species with polarversus temperate origin. Our findings suggest that the flowof major currents and the establishment of hydrographical frontsare of primary importance to the plankton communities in theWest Greenland shelf area, influencing the early life of fishand the recruitment to the important fisheries resources.     

Instar distribution and biomass of Chironomidae larvae in Lago El Junco, Isla San Cristobal, the Galápagos

The distribution, abundance and standing crop biomass of chironomid larvae were determined at one-meter depth intervals along three radial transects. Samples were collected by coring soft sediments while diving. Three genera were found in the lake: Chironomus sp. (collector-filtering larvae), Ablabesmyia sp. (predatory larvae) and Goeldichironomus sp. (collector-filtering larvae). Standing crop densities of chironomids, averaged over the entire lake, varied from 30,594 larvae/m² to 11,428 larvae/m² at different depths. No statistically significant zonation in density was found for the two most common taxa, Chironomus sp. (87.8% of specimens) and Ablabesmyia sp. (9.0%), however the deepest zones (>4 m) had the lowest estimated densities. Significant differences in standing crop biomass were detected, with the 6 m depth having greatest biomass. The increase in standing crop biomass was a function of (1) lower frequency of first instars of Chironomus sp. and Ablabesmyia sp. at 6 m (2) higher average larval biomass of both species at 6 m and (3) very significant increase in average biomass of fourth instars of Chironomus sp. at 6 m compared to fourth instars at shallower depths. These results indicate that the lentic chironomids of this isolated oceanic habitat consist of a small number of species that are ecological generalists and tolerant of low oxygen concentrations.     

Helminths of two anuran species, Atelopus spurrelli (Bufonidae) and Dendrobates histrionicus (Dendrobatidae), from Colombia, South America

Two species of anurans from Colombia, South America, Atelopus spurrelli and Dendrobates histrionicus, were examined for helminths. A. spurrelli was found to harbor three species of Nematoda, adults of Cosmocerca podicipinus and larvae of Physocephalus sp. and Porrocaecum sp. D. histrionicus was found to harbor, in addition to C. podicipinus, Physocephalus sp. and Porrocaecum sp. and cystacanths of three species of Acanthocephala: Centrorhynchus sp., Onicola sp. and Polymorphus sp. A. spurrelli and D. histrionicus represent new host records for these helminths.     

Diversity of anopheline mosquitoes (Diptera: Culicidae) and classification based on the characteristics of the habitats where they were collected in Puerto Iguazú, Misiones,Argentina

In order to extend the knowledge of anopheline diversity and their habitats in three environments with different degrees of anthropic intervention in Puerto Iguazú, Misiones, anopheline larvae were collected and classified on the basis of similarities of their habitats. Spatio‐temporal abundance was determined and larval diversity and complementarity index were calculated. Rank‐abundance curves were performed to compare the composition, abundance, and species evenness among environments. A total of 783 larvae, belonging to six species: Anopheles argyritarsis, An. fluminensis, An. mediopunctatus, An. punctimacula, An. strodei s.l., and An. triannulatus s.l., were collected. A cluster analysis and a principal component analysis detected two groups; exposure to sunlight and type of habitat were the characteristics that explained the grouping of species. Higher abundances of anopheline larvae were observed during autumn and spring. The greatest richness was recorded in wild and peri‐urban environments and the effective number of species was greater in the wild. Anopheles punctimacula and An. triannulatus s.l. are secondary vectors of malaria in other South American countries and both species were found in the three environments, so that deforestation poses a potential risk for malaria transmission as it contributes to the proliferation of larval habitats for these mosquitoes.