Distribution patterns of micro- and meso-zooplankton communities in sea ice regions of Lützow-Holm Bay, East Antarctica

In the Southern Ocean, zooplankton research has focused on krill and macro-zooplankton despite the high densities of micro- and meso-zooplankton. We investigated their community structure in relation to different sea ice conditions around Japan’s Syowa Station in Lützow-Holm Bay, in the summers of 2011 and 2012. Zooplankton samples were collected using vertical hauls (0–150 m), with a closing net of 100-μm mesh size. The results of cluster analysis showed that the communities in this region were separated into fast ice, pack ice, and open ocean fauna. The fast ice fauna had lower zooplankton abundance (393.8–958.9 inds. m^?3) and was dominated by cyclopoid copepods of Oncaea spp. (54.9–74.8 %) and Oithona similis (6.6–19.9 %). Deep-water calanoid copepods were also found at the fast ice stations. Pack ice and open ocean fauna had higher zooplankton abundance (943.6–2,639.8 inds. m^?3) and were characterized by a high density of foraminiferans in both years (6.6–61.9 %). Their test size distribution indicated that these organisms were possibly released from melting sea ice. The pteropod Limacina spp. was a major contributor to total abundance of zooplankton in the open ocean zone in 2012 (26.4 %). The physical and/or biological changes between 2 years may affect the abundance and distribution of the dominant zooplankton taxa such as cyclopoid copepods, foraminiferans, and pteropods. Information on the relationships between the different species associated with sea ice will help to infer the possible future impacts of climate change on the sea ice regions.     

Changes in Adélie penguin breeding populations in Lützow-Holm Bay, Antarctica, in relation to sea-ice conditions

The Adélie penguin, Pygoscelis adeliae, an important component of the Antarctic marine ecosystem, is closely associated with sea ice. Using data collected by Japanese Antarctic Research Expeditions since the 1960s, we examined trends in breeding populations of this species around Lützow-Holm Bay. Ten colonies ranging in size from 10 to 2,500 individuals were counted along the Soya Coast. Populations fluctuated synchronously, and overall increased at most colonies, except for two: one located deep inside the bay and another where human disturbance was substantial. Populations tended to increase during, or after, periods of sparse sea ice in summer, a condition that occurred once every decade. An increase in population size also occurred 5 years after a winter of extensive sea ice and after a winter of especially reduced sea ice.     

Mobile epiphytic invertebrates inhabiting the brown macroalga, Desmarestia chordalis, under the coastal fast ice of Lützow-Holm Bay, East Antarctica

The species composition of mobile epiphytic animals inhabiting the brown alga, Desmarestia chordalis Hooker and Harvey, in Lützow-Holm Bay, East Antarctica, was investigated. A total of 797 individual invertebrates in 22 taxa were collected from 3 clumps of algae. The assemblage was dominated by two amphipod crustaceans, Prostebbingia sp. and Haplocheira plumosa Stebbing, which composed 70.3% of the total number of individuals, followed by a gastropod species, Skenella paludinoides (Smith). The species composition differs from those found in previous studies conducted in Prydz Bay and Ross Sea, suggesting the existence of various types of epifaunal communities along the East-Antarctic coast.     

Biological characteristics of euphausiids preyed upon by Adélie penguins in relation to sea-ice conditions in Lützow-Holm Bay,Antarctica

We examined the biological characteristics of euphausiids found in the stomachs of Adélie penguins in relation to sea-ice conditions in Lützow-Holm Bay over three seasons. Euphausiids, especially Euphausia superba, proved to be a staple food for Adélie penguins irrespective of the ice condition. Body length and maturity-stage compositions of euphausiids were different among seasons, probably reflecting sea-ice condition in summer. The mean body length decreased and maturity regressed during each season in E. superba, which was partly attributable to the selective feeding on large, mature female krill by Adélie penguins. The 1995/1996 year class of E. superba, which was spawned when the sea ice was most developed, was strong and conspicuous in the 1996/1997 and 1997/1998 seasons. This vigor indicates that sea ice provided females with good spawning conditions and larvae with good growth and survival rates.     

Spatial structure of the soil seed bank of Poa annua L.—alien species in the Antarctica

Poa annua L. (annual bluegrass) is the only non–native flowering plant species that has successfully established a breeding population in the maritime Antarctic and has been shown to maintain a soil seed bank. The characteristic of the spatial structure of the Antarctic population of this species is the formation of distinct dense clumps—tussocks. In the temperate zone the species is only loosely tufted. We focused on the characteristics of seed deposition associated with the tussocks and some aspects of the spatial heterogeneity of the soil seed bank of P. annua in the Antarctic. We wanted to assess the microspatial structure of the soil seed bank of annual bluegrass at Arctowski Station. Therefore we compared the number of seeds deposited underneath and in the vicinity of P. annua clumps. Our results indicate that P. annua in the Antarctic maintains a soil seed bank comparable to species typical for the polar tundra. The microspatial structure of P. annua soil seed bank in the Antarctic is highly associated with the presence of tussocks. Seeds are deposited underneath the tussock rather than in the vicinity of the clump. Our results also indicate that seeds are able to survive the Antarctic winter and readily germinate under optimal conditions.     

Occurrence of cyclopoid copepods and faecal material in the Halley Bay region,Antarctica, during January–February 1991

Faecal material and cyclopoid copepods were collected during the expedition ANT IX/3, in the Halley Bay area (Weddell Sea, Antarctica), between January and February 1991. Faecal material comprised pellets produced by krill, copepods, ostracods and appendicularians. Cyclopoid copepods were represented by two genera, Oithona and Oncaea. In the Halley Bay area, higher concentrations of krill faecal material (420.9 mm³ m^–2) and chl.-a (39.3 mg m^–2) were found within the upper 200 m of the water column of the polynya than in ice-covered open-ocean areas (58.2 mm³m^–2 and 25.5 mg m^–2, respectively). At an ice-drift station, high concentrations of krill faecal strings under fest-ice were found. In addition, similarities between diatom assemblages in the pack-ice algae and krill faecal strings contents suggest an active utilization of ice-algae by krill populations. Sedimented material collected at 50 m depth by a sediment trap was dominated by krill faecal strings. Contents of small oval pellets (of probable cyclopoid copepod origin) resemble those of krill faecal pellets suggesting that coprophagy was involved. This suggestion is supported by: (1) The small quantity of food particles (other than krill faecal matter) available in the water column (< 0.3 g chl.-al^–1). (2) The negative in situ correlation between krill faecal strings and cyclopoid copepods. (3) The structure of cyclopoid copepod buccal appendages, which are more adapted for raptorial feeding.     

Distribution,biomass and production of Gracilaria in Lüderitz Bay,Namibia

The extent and biomass of the Gracilaria beds in the Lüderitz Bay area, Namibia were surveyed in winter and summer. The beds covered most of the suitable sediments available (grain size 106–212 μm) and did not occur in water shallower than 1 m or deeper than 11 m. Total surface area, most of which occurred in the Bay system, changed very little from winter to summer but biomass increased by 3.5 fold. In winter, total Gracilaria biomass was 200 t and 650 t and in summer, 150 t and 2850 t respectively in the Lagoon and Bay. Maximum biomass occurred at 3–4 m in the Lagoon and 5–6 m in the Bay in both winter and summer. Gracilaria beach cast data from 1987 to 1991 for the area were analysed for seasonality and, depending on the specific site, correlated with swell, southerly wind velocity and sea temperature. Beach cast in the Lagoon system is a more continuous process than in the Bay, where beach casts at most sites follow an annual pattern. Wind driven currents and chop were the most important causative parameters of beach cast in the Lagoon whereas the depth at which the plants were growing and swell were more important in the Bay system. The two systems viz. Lagoon and Bay are independent of one another with very little or no exchange of Gracilaria between them. This was evidenced by the similar percentage each contributes to the total beach cast and the similar pattern of beach cast from year to year. The decrease in total beach cast from 1989 to the end of the study period was attributed to a trend towards increasing swell height and low sea temperatures in 1991.     

Bioleaching in brackish waters—effect of chloride ions on the acidophile population and proteomes of model species

High concentrations of chloride ions inhibit the growth of acidophilic microorganisms used in biomining, a problem particularly relevant to Western Australian and Chilean biomining operations. Despite this, little is known about the mechanisms acidophiles adopt in order to tolerate high chloride ion concentrations. This study aimed to investigate the impact of increasing concentrations of chloride ions on the population dynamics of a mixed culture during pyrite bioleaching and apply proteomics to elucidate how two species from this mixed culture alter their proteomes under chloride stress. A mixture consisting of well-known biomining microorganisms and an enrichment culture obtained from an acidic saline drain were tested for their ability to bioleach pyrite in the presence of 0, 3.5, 7, and 20 g L⁻¹ NaCl. Microorganisms from the enrichment culture were found to out-compete the known biomining microorganisms, independent of the chloride ion concentration. The proteomes of the Gram-positive acidophile Acidimicrobium ferrooxidans and the Gram-negative acidophile Acidithiobacillus caldus grown in the presence or absence of chloride ions were investigated. Analysis of differential expression showed that acidophilic microorganisms adopted several changes in their proteomes in the presence of chloride ions, suggesting the following strategies to combat the NaCl stress: adaptation of the cell membrane, the accumulation of amino acids possibly as a form of osmoprotectant, and the expression of a YceI family protein involved in acid and osmotic-related stress.     

Characteristics of shell microstructure and growth analysis of the Antarctic bivalve <Emphasis Type="Italic">Laternula elliptica</Emphasis> from Lützow-Holm Bay,Antarctica

Growth performance of the Antarctic bivalve Laternula elliptica was examined both by shell microstructural observation and by applying a fluorescent substance, tetracycline, as a shell growth marker. The shell was composed of two calcareous layers: the thick outer layer was homogeneous or granular in structure and the thin inner layer was nacreous. The architecture of Antarctic L. elliptica was different from that of temperate L. marilina, and the ratio of thickness between the outer and inner layers appeared to be different. The growth rate of the nacreous layer was analyzed to be very low. High correlations were found between the major axis of chondrophore and both shell length and shell dry weight, respectively. It is suggested that the chondrophore is an appropriate growth indicator, and combining the information of growth increments with the fluorescent method may be useful in estimating the bivalve growth performance in the Antarctic sea.     

Spatial ecology and conservation of two sloth species in a cacao landscape in limón,Costa Rica

The spatial ecology of sloths was studied in an agricultural landscape in Limón Province, Costa Rica. Two sloth species, the three-toed sloth (Bradypus variegatus) and the two-toed sloth (Choloepus hoffmanni), actively used and traveled through a cacao agroforest and its contiguous living fence rows and riparian forests. This agroecosystem was embedded in an agricultural landscape dominated by banana and pineapple plantations and pastures with dispersed trees. The two-toed sloth (C. hoffmanni) was found in 101 tree species and used 34 for food; the three-toed sloth (B. variegatus) was found in 71 tree species and used 15 for food. Choice of preferred species differed between the two sloth species. Trees commonly used by sloths for food and/or refuge in the cacao agroforest included Erythrina poeppigiana, Cecropia obtusifolia, Leucaena leucocephala; in the living fence rows, Cordia alliodora, Erythrina poeppigiana, Ocotea sinuata and Trophis racemosa; in the riparian forests, Coussapoa villosa, Cecropia obtusifolia, Hura crepitans, Pterocarpus officinalis and Spondias mombin; and in the pastures with dispersed trees, Cordia alliodora, Coussapoa villosa, Erythrina poeppigiana, Ocotea sinuata and Hura crepitans. This study demonstrates the importance of the cacao agroforest as well as arboreal elements in other land uses in providing resources for sloth conservation in a larger agricultural landscape.     

Spatiotemporal dynamics of duck harvest distributions in the Central and Mississippi flyways, 1960–2019

Geographical distributions of waterfowl exhibit annual variation in response to spatiotemporal variation in weather conditions, habitat availability, and other factors. Continuing changes in climate and land use could lead to persistent shifts of waterfowl distributions, potentially causing a mismatch with habitat conservation planning, wetland restoration efforts, and harvest management decisions informed by historical distributions. We used band recoveries and harvest records (i.e., hunter-harvested wings) from the United States Fish and Wildlife Service Waterfowl Parts Collection Survey as indices of duck distribution in autumn and winter, and quantified intra-annual, interannual, and interspecific variation in their geographic distributions across 6 decades (1960–2019) for 15 duck species in the Central and Mississippi flyways in North America. Specifically, we tested for annual and decadal shifts in mean latitude and longitude of recoveries for each month (Oct–Jan) by species and taxonomic guild (i.e., dabbling, diving ducks). Overall, species varied in the extent, timing, and sometimes direction, of distributional change in recoveries. From 1960–2019, mean recovery locations for dabbling ducks shifted south 105–296 km in October and 27 km in November (wings only), whereas mean latitudes shifted north 144–234 km in December and 186–301 km in January. Mean recovery locations for diving ducks shifted north 162 km in October (wings only), 84–173 km in December, and 66–120 km in January, but shifted 99–512 km south in November. Shifts in longitude were less consistent between guilds and data types. Finally, distributional change rarely accelerated during recent decades, except for southward shifts of band recoveries of diving ducks in November and northward shifts of band and wing recoveries of dabbling ducks in January. Although anecdotal accounts of large-scale northward shifts in duck distributions are prolific in the land management and hunting communities, our data demonstrate more subtle shifts that vary considerably by species and month. Observed changes in recovery distributions could necessitate changes in timing of habitat management practices throughout the Central and Mississippi flyways and may result in fewer hunting and recreational opportunities for some species in southern states. Quantifying patterns of historical change is a necessary first step to understanding temporal and interspecific variation in waterfowl distributions, which will help with landscape-scale conservation and management efforts in the future and enable effective communication to core constituencies regarding ongoing changes and their implications for recreational engagement.     

Spatial patterns in fish distributions and structure of the ichthyocenosis in the Água Nanci stream,upper Paraná River basin,Brazil

Samples of fishes were collected quarterly at three reaches in the Água Nanci stream, upper Paraná River basin, Brazil: near the spring, in the middle course, and near the mouth. Richness and evenness of the fish fauna increased between reaches towards the river mouth showing a correlation with stream width, pH and the presence of riparian vegetation. These variations in species richness and evenness, verified through Principal Component Analysis and Pearson correlation, suggest relations to habitat complexity, especially characterized by both the degree of preservation of dense riparian vegetation and high width at the lower reaches of the stream, providing a wide variety of hiding places for fish. Abundant species showed correlations with some environmental factors, suggesting habitat preferences.     

On the population dynamics and ecology of the shrimp species (Crustacea,Decapoda, Natantia) in the Central Amazonian river Tarumã-Mirim

Summary Collections over four years in the habitat of submerged litter show that shrimps are abundant the year round. Mean densities vary from 5–45 animals/m² of litter habitat. Finegrained density distribution within litter sites is highly clumped, but coarse-grained distribution in any given month between litter sites along the river is grosso-modo random.Density and species distribution are a function of the annual cycles of inundations. Of the five species (of a total of seven in the area) that were found to be breeding in the litter habitat it could be established that reproduction is restricted to the period of rising and highest water levels. Reproduction is low in all species, namely below 20 eggs per egg batch with essentially a single generation per year.Breeding ecology in relation to the litter habitat is briefly discussed.This project was supported jointly by the CNPq (Brasilian Research Council), by the OAS (Organization of the American States) and by the SUFRAMA (Financing body of local government)     

The style–length of the female florets and their fate in two dioecious species of Xishuangbanna, China

Constraints and evolution are central for the resolution of conflicts between mutualism species and for the stability of mutualisms. Dioecious fig species and their specific pollinators are also in conflict on the use of fig ovaries. Here, our experiments provided some data on the female florets allocation in two dioecious fig trees. The results showed that: (1) there is a bimodal distribution in the style–length of two fig trees’ female florets, moreover, the style–lengths are fairly similar and narrowly distributed in gall figs and more variation seems to occur in seed figs; (2) the styles in seed figs are a little longer than those in gall figs; (3) the pollinator's ovipositor lengths are shorter than the style–lengths in seed figs, but they are very similar to those in gall figs so that pollinators can only lay their eggs into the ovaries of gall figs, but not in seed figs; (4) the stigmas stick together, and the style is curly and flexible in seed syconia of the two fig species studied, so it is very difficult for the pollinators to find suitable ovipositing sites and lay their eggs in seed figs; (5) the variations of style-lengths are bigger in seed figs than gall figs, but they are smaller in dioecious figs than monoecious figs; (6) for Ficus cyrtophylla, about 10% styles are shorter in seed figs than those in gall figs, even shorter than ovipositor. In contrast, about 2% styles in gall figs of Ficus hispida are longer than its corresponding pollinator's ovipositor. In a word, our study suggests that the female floret's fate in these two fig species is mainly dependent on its style–length, but not all. The stigma shape and the floral organization can both also attribute to their fate in the two fig species studied.     

Rana temporaria metamorph production and population dynamics in the field – Effects of tadpole density,predation and pond drying

This study investigates factors of importance for tadpoles survival and metamorph production in the common frog Rana temporaria. It also assess the importance of this for the population dynamics of the species. Eighteen ponds were studied for up to 8 years. Data collected each year included: number of spawn clumps deposited, tadpole number and metamorph number. The permanency of the ponds was also recorded each year. Measures were taken of predator density. There was no suggestion of density dependence in the survival of tadpoles. In contrast, the number of spawn clumps deposited per pond area was highest for ponds with high survival. Density of predators (sticklebacks, newts and invertebrates) was negatively correlated to tadpole and metamorph survival. This was true both within (among years) and among ponds. Several of the study ponds dried completely before metamorphosis in some years. However, those ponds also were those with the smallest number of predators and in years with successful metamorphosis, these ponds produced more metamorphs than more permanent ponds. An analysis of the year to year dynamics showed that population size (number of deposited spawn clumps) was correlated to that in the previous year, suggesting a fairly high adult survival, but also on the number of metamorphs emerging two or three years before (corresponding to the age of sexual maturity of the species). It is concluded that the aquatic stage is not strongly limiting in these ponds but conservation efforts should be focused on the terrestrial habitat. Also, the study stresses the value of temporary ponds, despite the fact that recruitment often fails totally in these.     

On the identity of two Antarctic brooding nemerteans: redescription of Antarctonemertes valida (Bürger, 1893) and description of a new species in the genus Antarctonemertes Friedrich, 1955 (Nemertea, Hoplonemertea)

Nemerteans (ribbon worms) constitute an abundant and occasionally conspicuous group of benthic invertebrates in the Southern Ocean. Although recent work has confirmed that this group is far more diverse than previously recognized, the Antarctic nemertean fauna remains poorly understood when compared to other geographic regions. In most cases, the taxonomic information on the known nemertean fauna is incomplete for this region and/or has been inappropriately documented. As a consequence, many of the species described are considered species inquirendae. Among the nearly 50 species described so far for the Southern Ocean, two hoplonemerteans are known to brood eggs in cocoons: Amphiporus incubator Joubin, 1914 and Amphiporus michaelseni Bürger, 1895a. Here, we redescribe Antarctonemertes valida (Bürger, 1893), a senior synonym of A. michaelseni, and describe a new congeneric species, Antarctonemertes riesgoae sp. nov. Both species show a similar reproductive strategy by brooding their cocoons, and similar external appearance, but clearly differ in other aspects of their morphology, such as the cephalic coloration pattern and the number of proboscidial nerves. We provide novel information about their life habitus, reproductive behaviour, internal anatomy, and their phylogenetic placement within hoplonemerteans using one nuclear (28S rRNA) and two mitochondrial [cytochrome c oxidase subunit I (COI) and 16S rRNA] markers. We also provide a parsimony haplotype network using 16S rRNA, COI, and the internal transcribed spacer region 2 (ITS-2) showing a clear distinction between individuals of both species. Our results stress the need of combining molecular and morphological information when dealing with closely related species of nemerteans.     

Zooplankton excretion and NH 4 + cycling in near-surface waters of the Southern Ocean. I. Ross sea,austral summer 1977–1978

Summary Ammonium (NH ₄ ⁺ ) is a preferred nitrogen source for Antarctic phytoplankton growth and the principal nitrogenous waste excreted by zooplankton and micronekton. In austral summer 1977–1978, NH ₄ ⁺ was present at average concentrations of 0.1–0.3 g-at liter^-1 in the upper 50 m of the Ross Sea and was excreted by resident mixed zooplankton at rates of 1.6 g-at NH ₄ ⁺ g^-1 wet weight h^-1. Zooplankton biomass sampled by vertically-towed 0.5 m nets averaged 0.06 ml m^-3 in the upper 200 m over the Ross Sea shelf and 0.09 ml m^-3 in the upper 200 m north of the shelf-slope front. Olson (1980) has reported that phytoplankton nitrogenous requirements were 110 and 170 g-at NH ₄ ⁺ m^-3 day^-1 in these respective regions. A synthesis of these data predicts that average summertime standing crops of zooplankton might regenerate only about 2% of the daily NH ₄ ⁺ requirements of Ross Sea phytoplankton. For comparison, the potential NH ₄ ⁺ excretion impact of microheterotrophs, seabirds, and local aggregations of zooplankton are discussed and contrasted with non-biogenic inputs of NH ₄ ⁺ associated with basal meltwater from the Ross Ice Shelf and the seasonal melting of the sea ice pack.     

Species, dynamics and population composition of phthirapteran in free-range chickens (Gallus gallus L.) in São Luis Island, State of Maranhão

The objective of this work was to identify the phthirapteran species, to determine the prevalence according to the anatomical region of the body and to know the dynamics and composition of the population of these ectoparasites in free-range chicken in S?o Luis Island, state of Maranh?o. Inspection was performed in 40 chickens and feathers were collected from the head, neck, wing, thigh, dorsal and ventral regions and cloacae. The phthirapteran species identified were: Menopon gallinae L., Menacanthus stramineus Nitzsch, Menacanthus pallidulus Neumann, Menacanthus cornutus Schommer (Menoponidae), and Lipeurus caponis L., Goniodes dissimilis Denny and Goniocotes gallinae De Geer (Philopteridae). L. caponis was collected from all regions sampled, including the head, which was the least infested region. The dorsum was the most infested, especially in the dry period of the year and where the greater parasitic diversity was observed, the wing and the head were the least infested regions. Considering the dynamics and the composition of the population the phthirapteran presented a prevalence of 85% of the sampled chickens, the mean intensity of infestation was 45.3 varying from <1 to 453. The egg stage was superior to the others life stages followed by nymphs and female adults, independent of the phthirapteran species.