Abundance Of Zooplankton Species Research Articles

Peptidergic signaling in Calanus finmarchicus (Crustacea, Copepoda): In silico identification of putative peptide hormones and their receptors using a de novo assembled transcriptome

The copepod Calanus finmarchicus is the most abundant zooplankton species in the North Atlantic. While the life history of this crustacean is well studied, little is known about its peptidergic signaling systems despite the fact that these pathways are undoubtedly important components of its physiological/behavioral control systems. Here we have generated and used a de novo assembled transcriptome for C. finmarchicus (206,041 sequences in total) to identify peptide precursor proteins and receptors. Using known protein queries, 34 transcripts encoding peptide preprohormones and 18 encoding peptide receptors were identified. Using a combination of online software programs and homology to known arthropod isoforms, 148 mature peptides were predicted from the deduced precursors, including members of the allatostatin-A, allatostatin-B, allatostatin-C, bursicon, crustacean cardioactive peptide (CCAP), crustacean hyperglycemic hormone, diuretic hormone 31 (DH31), diuretic hormone 44 (DH44), FMRFamide-like peptide (myosuppressin, neuropeptide F [NPF] and extended FL/IRFamide subfamilies), leucokinin, neuroparsin, orcokinin, orcomyotropin, periviscerokinin, RYamide and tachykinin-related peptide (TRP) families. The identified receptors included ones for allatostatin-A, allatostatin-C, bursicon, CCAP, DH31, DH44, ecdysis-triggering hormone, NPF, short NPF, FMRFamide, insulin-like peptide, leucokinin, periviscerokinin, pigment dispersing hormone, and TRP. Developmental profiling of the identified transcripts in embryos, early nauplii, late nauplii, early copepodites, late copepodites, and adult females was also undertaken, with all showing the highest expression levels in the naupliar and copepodite stages. Collectively, these data radically expand the catalog of known C. finmarchicus peptidergic signaling proteins and provide a foundation for experiments directed at understanding the physiological roles served by them in this species.

Arsenic distribution and speciation in Daphnia pulex

Rat Lake, Yellowknife, Northwest Territories, is situated on arsenic-rich tailings from a historical gold mine. The abundant zooplankton species Daphnia pulex in this lake was used to study the impact of arsenic at the base of the freshwater food web; the speciation and distribution of arsenic in D. pulex and its food sources; and the origin of formation of organoarsenicals in freshwater systems. The arsenic concentration in lake water was measured as 0.25mgL−1, while the zooplankton organisms contained up to 35mgkg−1 d.w. arsenic. Plankton samples were analyzed for arsenic speciation, by using X-ray Absorption Near Edge Structure (XANES) on the whole, dried samples and High Performance Liquid Chromatography coupled to Inductively Coupled Plasma Mass Spectrometry (HPLC-ICP-MS) on water extracts. XANES data suggest that D. pulex mainly contain inorganic arsenicals with 56% of arsenic with +5 oxidation state and 10% of arsenic with +3 oxidation state, but also 34% of organoarsenic compounds that were identified with HPLC-ICP-MS as monomethylarsonate (MMA), dimethylarsinate (DMA), and arsenosugars. The most abundant of the organoarsenicals was the glycerol sugar (Sugar 1). X-ray Fluorescence (XRF) mapping of D. pulex for arsenic distribution showed that arsenic was mainly distributed in the gut of the animal, where its concentration was ten times higher than in the surrounding tissues. Moreover, the analysis of residues from extractions targeting water-soluble and lipid-soluble arsenicals suggested that part of the measured arsenic signal comes from ingested sediments, phytoplankton, or other food sources. These food sources contain inorganic arsenic only, with AsV–O in phytoplankton and AsIII–S in sediments, suggesting the possibility that the organoarsenicals compounds detected in the tissues of the organism are created by the Daphnia.

Plankton distribution and diversity: a case study of earthen fish ponds in the Obubra Campus of Cross River University of Technology

Our knowledge of the consumption of plankton by fish is still fragmentary. Trophic links between fish and plankton are often loose because plankton is a changing assemblage of pelagic organisms of valuable nutritional value. The objectives of the study were to determine the distribution and diversity of planktons in the fish ponds. Water samples for plankton analysis were collected monthly (January – December), along with water samples used for the determination of physico-chemical parameters in 250ml bottles in Ponds 1,2 and 5. The freshwater sample was mixed gently and pipetted into 5ml plankton chamber containing 2 drops of Lugol’s solution. The Lugol’s solution which served as fixative also enhanced sedimentation of the organisms and was left overnight before analyzing plankton using Zeiss inverted plankton microscope and plankton determination keys. Data was analyzed using Shannon-Weaner diversity index, species richness, means and analysis of varians (ANOVA).The results showed that the highest species richness for dry season phytoplankton value of 27 was recorded in Pond 2, with the highest Shannon-Weaner diversity index value of 0.5401 in pond 5. Merismopaedia elegans with 3,434 in pond 2 was the most abundant phytoplankton species and chlorophyceae the most dominant taxa. The rainy season zooplankton species richness values (5 in pond 2) were higher than that of the dry season (3 in pond 3) with the highest Shannon-Weaner index value of 0.3501 recorded in pond 1. The most abundant zooplankton species Asplanchna species 57 was recorded in pond 2. Significant differences (p

Light-dependent behavior of abundant zooplankton species in the White Sea

Light-dependent behavior of the abundant zooplankton species inhabiting the White Sea were studied experimentally during: (i) the spring equinox (March); (ii) the polar day (late May to June), (iii) August, 17/7 h day-night light cycle, (iv) the fall equinox (October). Behavioral patterns were investigated for eight species of Copepoda (Metridia longa, Calanus glacialis, Pseudocalanus minutus, Oithona similis, Oncaea borealis, Temora longicornis, Centropages hamatus, Acartia spp.), one Cladocera species (Evadne nordmanni) and Polychaeta larvae. The hypothesis was tested that attraction to (or repulsion from) light is the primary mechanism involved in the vertical migration of zooplankton with different trophic characteristics in relation to phytoplankton-rich upper water layer. The impact of red (680 nm), yellow (560 nm) and UV (280 nm) light was tested. The animals were acclimated to two food conditions: natural seawater (satiated) and filtered (1 μm) seawater (hungry). The positive light response of predominantly herbivorous and omnivorous copepods and cladocerans inhabiting the photic water layer corresponds with their distribution and their food vertical distribution. Hungry animals display the strongest responses to light. Light effects on behavior were weak in deep-dwelling 0. borealis. We suggest that red and yellow light is an indicator of the photic layer (high food concentration) to zooplankton groups that feed on phytoplankton. In contrast, diapausing (e.g. non-feeding) copepods totally avoid light, especially when they hibernate in the aphotic layer. We hypothesize that there is a relationship between the light response of the zooplankton, their trophic characteristics, migration behavior (diel and ontogenetic) and the water layer occupied.

Approaching storm: Disappearing winter bloom in Lake Michigan

Between 1990 and 2001, late-winter phytoplankton blooms were common in parts of the lower Great Lakes (southern Lake Michigan, Saginaw Bay and southern Lake Huron, and western Lake Erie), providing resources for over-wintering zooplankton. In Lake Michigan up to 2001, detailed remote sensing and ship studies documented well-developed late-winter blooms in the southern gyre (circular bloom termed the ‘doughnut’). However, from 2001 to 2008, the winter blooms in Lake Michigan also supported early season veliger larvae from the introduced, cold-water adapted “profunda” morph of quagga mussels ( Dreissena rostriformis bugensis). Remote sensing and ship studies revealed that settled mussels caused an extraordinary increase in water transparency and a simultaneous decrease of Chl a in the late-winter bloom. Before quagga mussels in 2001, water transparency was 74–85% at deep-water sites, whereas it increased progressively to 89% by 2006 and 94–96% by 2008. Chlorophyll a concentrations in the gyre rings were 1.1–2.6 µg/L in 2001, declining to 0.5–1.7 µg/L by 2006 and 0.4–1.5 µg/L by 2008. The reduction of Chl a in the winter bloom rings from 2001 to 2008 was 56–78% for the western limb and 74–75% for the eastern limb. Zooplankton species abundance, composition and abundance also changed, as cyclopoid copepods became very scarce and over-wintering omnivorous calanoid copepods declined. Reduction in late-winter phytoplankton and zooplankton poses a serious threat to open-water food webs.

A study of zooplankton diversity with special reference to their concentration in River Ganga at Haridwar

The purpose of this study was to assess the zooplankton abundance and their monthly variation in river Ganga water. Zooplankton could be the bio-indicator of health status of an aquatic system and their study. The out come of this study shows that the most abundant zooplankton species was Ceriodaphnia throughout the study period and total number of zooplankton is high during winter season when the temperature is relatively low.

Salinity regulation of zooplanktonic abundance and vertical distribution in two saline meromictic lakes in south central British Columbia

Zooplankton species abundance and vertical distribution were followed in two south-central British Columbia saline meromictic lakes during the recent decade of their declining water levels. The lower salinity mixolimnion (0–7 m) of both lakes circulates partially most years down to their primary chemoclines marked by a 10–15 cm layer of purple sulfur bacteria (Amoebobacter purpureus) heavily grazed upon mainly by late copepodite stages and adults of Diaptomus connexus, possibly by some rotifers, but apparently not by cladocerans. Vertical distribution profiles, over an 8-year period, are presented mainly for the rotifer Brachionus plicatilis, two cladocerans Ceriodaphnia lacustris, and Daphnia pulicaria, as well as copepodite and adult D. connexus during normal periods of unimeromixis and a period of weak bimeromixis caused by shallow upper low salinity layers coming from drainage basin inputs.

Sedimentary records of reduction in resting egg production of Daphnia galeata in Lake Biwa during the 20th century: a possible effect of winter warming

To clarify long-term variations in the resting egg production of Daphnia galeata in Lake Biwa during the 20th century, we examined an abundance of plankton remains and ephippia in a 26-cm sediment core with a time resolution of approximately 2–6 years. Historical changes shown by these plankton remains indicated that the Daphnia population has not produced resting eggs since the 1980s, but it has remained the most abundant zooplankton species in the lake. Plankton monitoring data collected from 1966 to 2000 revealed that the overwintering individuals (January–March) of D. galeata plankters showed a significant increasing trend in recent years, such increase being negatively correlated with ephippial abundance in the sediment samples. Further analyses showed that the dominant phytoplankton in winter has changed from large inedible diatoms to edible flagellated algae, probably due to changes in vertical mixing regimes resulting from winter warming. These changes that occurred in the last several decades suggest that global warming has improved winter food conditions and thus enabled the Daphnia plankton to maintain its population without producing resting eggs in Lake Biwa.

Expression of ecdysteroids and cytochrome P450 enzymes during lipid turnover and reproduction in Calanus finmarchicus (Crustacea: Copepoda)

The marine copepod Calanus finmarchicus is the most abundant zooplankton species in the northern regions of the Atlantic Ocean and the Barents Sea. Very little is known about molecular regulation of hormone metabolism, moulting and reproduction in copepods. To investigate these processes, we sampled adult male and female copepods (females at three distinct reproductive stages) and copepodites stage five (CV) from the culture at SINTEF/NTNU Sealab. Copepods were individually photographed, analyzed biometrically (body size, length and lipid storage size) and for ecdysteroid concentrations. In addition, we analyzed copepods for gene expression of three putative cytochrome P450 enzymes possibly involved in ecdysteroid regulation: CYP301A1, CYP305A1 and CYP330A1. The CV group exhibited the highest ecdysteroid concentrations and the largest lipid storage size, and a significant positive correlation was found between these parameters. Also, two of the P450 enzymes (CYP305A1 and CYP330A1) were more highly expressed at CV than at the adult stage, suggesting that these P450 enzymes are involved in ecdysteroid synthesis and lipid storage regulation. The expression of CYP330A1 was higher in newly moulted females than in females that had produced eggs. In addition, we observed that ecdysteroid concentrations were higher in females with large egg sacs, suggesting that ecdysteroids may be involved in egg maturation and reproduction. The CYP301A1 was more highly expressed in males and post-spawning females, and may be involved in ecdysteroid degradation since these groups also exhibited the lowest ecdysteroid concentrations.

A late Holocene paleo-productivity record in the western Gulf of Maine, USA, inferred from growth histories of the long-lived ocean quahog (Arctica islandica)

To investigate environmental variability during the late Holocene in the western Gulf of Maine, USA, we collected a 142-year-old living bivalve (Arctica islandica) in 2004, and three fossil A. islandica shells of the Medieval Warm Period (MWP) and late MWP / Little Ice Age (LIA) period (corrected 14CAMS = 1030 ± 78 ad; 1320 ± 45 ad; 1357 ± 40 ad) in 1996. We compared the growth record of the modern shell with continuous plankton recorder (CPR) time-series (1961–2003) from the Gulf of Maine. A significant correlation (r2 = 0.55; p < 0.0001) exists between the standardized annual growth index (SGI) of the modern shell and the relative abundance of zooplankton species Calanus finmarchicus. We therefore propose that SGI data from A. islandica is a valid proxy for paleo-productivity of at least one major zooplankton taxa. SGIs from these shells reveal significant periods of 2–6 years (NAO-like) based on wavelet analysis, multitaper method (MTM) analysis and singular spectrum analysis (SSA) during the late Holocene. Based on established physical oceanographic observation in the Gulf of Maine, we suggest that slope water variability coupled with North Atlantic Oscillation (NAO) dynamics is primarily responsible for the observed SGI variability.

Effects of silt loading on the feeding and mortality of the mysid Mesopodopsis africana in the St. Lucia Estuary, South Africa

Mesopodopsis africana is an abundant zooplankton species in the currently drought stricken St. Lucia Estuary. The estuary is freshwater-starved, partly because its connection with the large Mfolozi catchment has been discontinued. This is due to the extremely high silt load carried by its waters. A series of in vitro experiments were conducted in May, July, August and December 2006, in order to determine the effect of silt loading on the feeding rate and mortality of M. africana. Mysids were subjected to different sediment concentrations in controlled experiments for a 12-hour period. The turbidity regimes were generated by adding pre-weighed silt concentrations, ranging from 0.03 g/L to 13 g/L, to natural estuarine water. Results in all cases showed a major effect of high silt levels upon food availability, as water chlorophyll losses increased with increased silt concentration. Hindrance in the food collecting abilities appears to have a compounding influence as on two occasions, May and August, ingestion rates decreased with an increase in silt concentration. However, in July, mysid ingestion and clearance rates were higher under increased suspended silt concentrations. In such cases, mysids may be clearing more water under conditions of low food concentration, or alternatively, they may switch to feeding on metazoan prey. In the December experiment, there was no relationship between ingestion rate and silt concentration, possibly because food supplies were sufficient to sustain constant ingestion rates or because mysids increased their clearance rates in the more turbid treatments to compensate for any negative effects of silt. Mysid health also declined, with the mean percentage of survivors decreasing consistently with an increase in silt concentration. Results indicate that the overall effect of increased silt load is negative, and subsequently, increased silt loading in the St. Lucia estuary is expected to have detrimental effects on communities of mysids within the estuary.

Coupling of the Biochemical Composition and Calorific Content of Zooplankters with the Microcystis aeruginosa Proliferation in a Highly Eutrophic Reservoir

The impact of the Cyanobacteria Microcystis aeruginosa on zooplankton dynamics was studied in the hypertrophic Villerest Reservoir (France). Samples were collected and their biochemical composition and calorific content examined. Three most abundant zooplankton species in the reservoir were considered: the cladoceran Daphnia longispina and the copepods Cyclops vicinus and Eudiaptomus gracilis. The three species were differently affected by the Microcystis aeruginosa blooms. Daphnia longispina did not seem to suffer from the proliferation of the M. aeruginosa, although its biomass decreased concomitantly to the bloom. This collapse would be attributable to the lack of nutritional value of algae. Cyclops vicinus seemed to move away when Microcystis invaded the superficial layers of the reservoir. Because this zooplankter had migratory abilities, it reached the littoral zone where food was available. The energetic costs linked to this migration were clearly pointed out when the species recovered the pelagial zone in early fall. The behaviour of Eudiaptomus gracilis was not clear. This species underwent diapause as M. aeruginosa proliferated. This suggests that Eudiaptomus gracilis moved away from the pelagial zone over the cyanobacterial blooms. In most cases, the cyanobacterial toxins affected the growth of zooplankton and the potential to use herbivorous zooplankton as a means to combat Microcystis proliferation in the Villerest reservoir seems limited.

Zooplankton structure and dynamics in permanent and temporary Mediterranean salt marshes: taxon-based and size-based approaches

Differences between zooplankton structure (species abundance and size distribution) and dynamics of permanent and temporary basins of a Mediterranean salt marsh (Emporda Wetlands, NE Spain) were analysed by means of taxon-based and size-based approaches. These basins are shallow bodies of water which are occasionally connected. They were isolated after water retreat from a broadly flooded, low-lying area close to the open sea. Although temporary and permanent basins show no differences in the most abundant zooplankton species, they differ in their zooplankton diversity, temporal pattern and size structure. The zooplankton assemblages of temporary basins exhibit a temporal pattern with six phases, which are conditioned to the hydrological cycle, each one dominated by one species, whereas in the permanent basin this temporal pattern shows only two phases. Zooplankton size distribution of the temporary basins is dominated by large sizes (copepodites and copepods) while the permanent basin is dominated mainly by small sizes (rotifera and nauplii of copepods). In the temporary basins, the shape of the biomass size spectrum changes according to the hydrological cycle and reflects the dynamics of the ecological interactions among zooplankton species. Differences in the zooplankton composition and dynamics of the permanent basin are not a consequence of water permanence but of the ecological interactions among species involved. The presence of a stable fish population in the permanent waters may explain the high values of zooplankton diversity and the low densities of large zooplankton.

Effect of Spatial Variation on Zooplankton Community Assessment in Fishery Studies

Many fishery researchers studying zooplankton abundance and size structure fail to implement a sampling protocol that addresses the horizontal distribution of zooplankton. Therefore, we assessed the horizontal and seasonal differences in the abundance and size structure of zooplankton in a small (43 ha) South Dakota impoundment. We collected zooplankton samples from vegetated, edge, and non-vegetated areas using a 1.5-m integrated tube sampler in May, June, and July 2001. Overall, Cyclopoida and Daphnia were more abundant in the vegetated area, but Calanoida were more abundant in the non-vegetated areas. Size differences were also found, but differences were inconsistent among months and habitat classifications. We also quantified the number of samples required to obtain a 20% coefficient of variation of the mean abundance of zooplankton species among months and habitat categories. The results of our study illustrate the importance of implementing a sampling design that accounts for the spatial variation in zooplankton.

Seasonal changes in the importance of the source of organic matter to the diet of zooplankton in Loch Ness, as indicated by stable isotope analysis

Seasonal variations in the stable isotope composition (d13C and d15C) of crustacean zooplankton and their putative food sources in oligotrophic Loch Ness were recorded during 1998. Bulk particulate organic matter (POM) showed d13C values consistent with a terrestrial plant origin from the catchment and exhibited little seasonal variation, whereas POM d15 was more variable, probably due to associated microbial action. In contrast, phytoplankton d13C was relatively light and showed some seasonal variation, but d15 values were more constant. The isotopic signatures of both POM and phytoplankton remained sufficiently distinct from each other throughout the period of study to allow their relative contributions to zooplankton diet to be assessed. Zooplankton isotopic signatures shifted seasonally, reflecting a dietary switch from a reliance on allochthonous carbon derived from POM during winter and early spring to heavy dependence on algal production during summer. Annually, crustacean zooplankton in Loch Ness derive approximately 40% of their body carbon from allochthonous sources, likely mediated via microbial links. Separate determination of isotope ratios for the main zooplankton species allowed a more detailed trophic investigation. The most abundant zooplankton species in the loch, Eudiaptomus gracilis, incorporated appreciable allochthonous carbon even during the peak of phytoplankton productivity. By contrast, Daphnia hyalina grew mainly in late summer and autumn and derived almost 100% body carbon from algal sources. This study is the first to quantify such a seasonal switch in zooplankton dependence between allochthonous and autochthonous sources of organic matter in a large lake.

Long-term dynamics of Asplanchna priodonta in Lake Windsborn with comments on the diet

We evaluate trophic interactions between the rotifer Asplanchna priodonta and the plankton community of Lake Windsborn (Eifel District, Germany). The long-term population dynamics of this species and of the two most abundant zooplankton species, Keratella cochlearis and Bosmina longirostris, were analyzed in relation to hydrochemical and climatic variates. The maximum abundance of A. priodonta was limited to the summer months with temperature being the only significant predictor of abundance. Intrinsic rate of growth and abundance of the three species were independent from each other suggesting the absence of trophic interactions. In Lake Windsborn, A. priodonta was a grazer rather than a predator. Its diet included high proportions of colonial algae and cyanobacteria which cannot be ingested by the other abundant zooplankton species, whereas zooplanktonic food were rarely found. Thus, our study supports the hypothesis that A. priodonta is an opportunistic feeder whose trophic position entirely depends on the structure of the plankton community.

Lake Shira, a Siberian salt lake: ecosystem structure and function. 2. Brachionus plicatilis (Rotatoria) growth and development

The growth and development of Brachionus plicatilis (Muller), a rotifer and one of the most abundant zooplankton species in Lake Shira, a saline lake at low temperature in the Republic of Khakassia, was studied in cultures at different trophic conditions. Growth indices were evaluated at natural (lake) concentrations of bacteria, Chlorella vulgaris, a microalga, and Candida utilis, a yeast. The negative effect on rotifer reproduction in the algal-bacterial community by blue-green algae was demonstrated. The ratio of ontogenetic periods was shown to be in accord with species and food concentration. Base values required to calculate B. plicatilis population simulation model parameters were defined.

Selective foraging behaviour of basking sharks on zooplankton in a small-scale front

The basking shark Cetorhinus maximus is the second largest fish species, attaining lengths of up to 11 m. During summer months in temperate coastal waters circumglobally, these sharks filter-feed on surface zooplankton1,2,3,4 near water-mass boundaries (fronts)5,6; however, little else is known about their biology1. Their foraging behaviour has not been investigated until now, although they have been described2 as indiscriminate planktivores that are unlikely to orientate to specific plankton-rich waters. We have now tracked basking sharks responding to zooplankton gradients. We show that they are selective filter-feeders that choose the richest, most profitable plankton patches. They forage along thermal fronts and actively select areas that contain high densities of large zooplankton above a threshold density. They remain for up to 27 hours in rich patches that are transported by tidal currents and move between patches over periods of 1–2 days. We mapped feeding locations of these sharks in two years; the maps show that these sharks indicate broad shifts in front-located secondary production. Foraging behaviour of basking sharks therefore indicates the distribution, density and characteristics of zooplankton directly. This makes these sharks unique biological ‘plankton recorders’, with potential use as detectors of trends in abundance of zooplankton species that are influenced by climatic fluctuations of the North Atlantic Oscillation7.

Recurrent response patterns of a zooplankton community to whole‐lake fish manipulation

SUMMARY1. In a series of whole‐lake manipulations conducted from 1984 to 1991, planktivorous fishes were alternately removed and restocked in a small mesotrophic lake, resulting in dramatic changes in the zooplankton community.2. Response patterns in the zooplankton community, which include species and size structure, and within‐year community variability, were examined. Variation in the zooplankton community in unmanipulated years was much lower than that in manipulated years, regardless of direction of the manipulation (i.e. decreasing or increasing planktivory).3. The succession of zooplankton species abundance was repeated in the second removal of planktivorous fishes. The community shifted from small‐bodied cladocerans, copepods and rotifers, through an intermediate state with high abundance of Holopedium, to an assemblage dominated by large‐bodied daphnids.

Historic Changes in Lake Michigan Zooplankton Community Structure: The 1960s Revisited with Implications for Top-Down Control

Recent changes in the Lake Michigan ecosystem provide a benchmark against which to reevaluate historic data. During the 1960s, the alewife (Alosa pseudoharengus) population exploded and then crashed. Offshore zoo-plankton data for the summers of 1954, 1966, and 1968 provided evidence that variations in alewife abundance had a major effect on zooplankton community structure. Based on these observations, other researchers have hypothesized that increased and decreased phytoplankton abundances during the 1960s as recorded at the Chicago water filtration plant were due to top-down effects rather than to phosphorus loading. This argument is reevaluated using two approaches. First, from the relationship between interannual variability in alewife and zooplankton species abundance during the summers of 1954, 1966, 1968, 1977, 1982, and 1984–87, I conclude that the effects of alewife predation on zooplankton community structure during the 1960s are less clear then originally proposed. Second, from estimates of Daphnia spp. grazing rates, considerations of the source of the long-term phytoplankton data used to support the top-down argument, regional differences in phytoplankton, zooplankton and alewife abundance trends, and historic water clarity observations, I conclude that existing data are insufficient to support the top-down argument that long-term trends in phytoplankton abundance were primarily affected by fluctuations in alewife abundance.