The Freshwater co-occurrence of Eurytemora Affinis (Copepoda: Calanoida) and Manayunkia Speciosa (Annelida: Polychaeta): Possible relicts of a marine incursion

The copepod Eurytemora affinis (Poppe, 1880) and the polychaete Manayunkia speciosa Leidy, 1858 have been found in similar habitats within the Ottawa River. As both species show strong marine affinities and co-occurrence is not restricted to the Ottawa River, but rather is the pattern for North America, present evidence supports the theory that these animals may be relict forms resulting from the most recent marine incursion.

---

Resumé Le copepode Eutytemora affinis (Poppe, 1880) et le polychete Manayunkia speciosa Leidy, 1858 ont étés trouvé en pareils habitats dans la Rivière Ottawa. Comme les deux espèces demontrent de grades affinités marines et ne sont pas restreintes à apparaître ensemble dans la Rivière Ottawa, mais plutôt suivent le patron de l'Amérique du Nord, la preuve présentée appuit la théorie que ces animaux purrainent être des formes reliques resultant de l'incusrion marine la plus récente.

     

Ovigerity,selective predation,and variable diel vertical migration in Euchaeta elongata (Copepoda: Calanoida)

Summary We present a statistical analysis of a previously published (Yen, 1983) but heretofore unanalyzed data set on the vertical distributions and diel vertical migration (DVM) of adult females of the marine planktonic copepod Euchaeta elongata in Dabob Bay, Washington, USA. Non-ovigerous females were strongly migratory on all four dates sampled, residing between 75–175 m during the day and at shallower depths during the night, commonly entering the upper 50 m of the water column. In contrast, ovigerous females were non-migratory or weakly migratory, largely remaining between 100–175 m both day and night, and entering the upper 50 m of the water column only rarely. Thus non-ovigerous females always migrated much more strongly, as measured by both amplitude of migration and the proportion of animals migrating, than did ovigerous females. These results led us to hypothesize that differential susceptibility to visually orienting predators was the cause of these differences in DVM behavior in female E. elongata, and we subsequently undertook an experimental study of the feeding selectivity of the copepod's natural predator, Pacific herring (Clupea harengus pallasi). Pacific herring exhibited a highly significant preference for ovigerous over nonovigerous adult female E. elongata. The demographic consequences of variable DVM in adult female E. elongata were investigated by way of life table analyses. Results indicated that under conditions of thermal stratification of the water column there is a distinct demographic disadvantage (reduced rate of realized population growth) incurred by non-migratory or weakly migratory ovigerous females due to delayed egg development at cooler subsurface temperatures. We conclude that ovigerous female E. elongata remain at depth both day and night to avoid visually orienting predators, and that such behavior must afford the copepod a demographic advantage of no less than a 26% reduction in adult mortality to offset the demographic cost of delayed egg development.     

Ecological remarks on Mastigodiaptomus nesus Bowman, 1986(Copepoda: Calanoida) in a Mexican karstic sinkhole

Mastigodiaptomus nesus(Bowman, 1986) was previously described from the West Indies, and its distribution was considered restricted to these islands. Recently it has been detected in several systems from the continental Yucatan Peninsula in Mexico. In this study, we contribute to the body size variability, abundance, distribution and vertical migration of Mastigodiaptomus nesus dwelling in a small, deep (264 m ², 47 m deep) karstic beaker-shaped sinkhole, located in this Peninsula. Here, this species is an important component of the zooplankton community during all the year. We analyzed the relationship between its abundance and concentration of nutrients (NO ⁻³), and Chlorophyll α. Differences in body size by sex (F = 67.56, p < 0.0001; n = 180), and sampled season (F = 6.59, p < 0.01; n = 180) were found. When animals from this sinkhole were compared with other localities, size difference was detected. Bigger animals were found in the West Indies, and smaller ones in continental localities. The nauplii were the most abundant development instars, followed by copepodids, and adults. In general, all developmental instars had a normal migration, with higher abundance at night time in upper layers (0.5 and 5 m), and diminishing towards daylight time. Direction of migrations seems to be towards the walls of the sinkhole (horizontal migration) instead of the deeper water layers, suggesting that these copepods are hidden in the irregular calcareous walls of the sinkhole. Abundance of total copepodid developmental stages were correlated with the Chl-α concentration. In addition, we found a highly significant difference between Chl-α concentration (F = 24.172, p < 0.001, n = 72), and NO ⁻³ concentration at all strata among seasons (F=25.46, p < 0.001, n = 60). Our results suggest that the body size of M. nesus is influenced by the nutrient concentration, and its vertical abundance and distribution may be explained by food availability.     

Diel vertical migration and gut pigment rhythm of Paracalanus parvus,P. crassirostris,Acartia erythraea and Eucalanus subcrassus (Copepoda,Calanoida) in Tolo Harbour,Hong Kong

Diel vertical migration and gut pigment rhythm of calanoid copepods were studied in the highly eutrophic waters of Tolo Harbour, Hong Kong in summer between July 30 and August l, 1991 and in winter between January 24 and 25, 1992. Paracalanus parvus and P. crassirostris showed neither diel vertical migration nor diel gut pigment rhythm during the summer study. Acartia erythraea and Eucalanus subcrassus exhibited prominent diel vertical migration and diel gut pigment rhythm. Diel changes in gut pigment content of surface dwelling individuals and increase of gut pigment content before the onset of nocturnal upward migration suggest that gut pigment rhythm in E. subcrassus was not the result of animals moving in and out of a food-rich surface layer. During the winter study, the harbour was affected by a bloom of Noctiluca scintillans. P. parvus and P. crassirostris resided in deeper waters presumably to avoid the dense populations of N. scintillans at the surface. P. crassirostris remained non-migratory during the winter study. There was a nocturnal increase in the number of P. parvus in the surface waters, although no diel change in the mean depth of the population was observed. Both Paracalanus species showed diel gut pigment rhythm. The presence of diel gut pigment rhythm in the non-migratory P. crassirostris during the winter study suggested the presence of an independent feeding rhythm.     

Effects of salinity and temperature on the expression of enzymatic biomarkers in Eurytemora affinis (Calanoida, Copepoda)

In order to establish effective enzymatic biomarkers that could provide in situ early warning of contaminant exposure in estuarine ecosystems, the potential effects of the principal abiotic factors (temperature and salinity) were investigated on common biomarkers, the acetylcholinesterase (AChE) and the glutathione S-transferase (GST) in Eurytemora affinis. Short term salinity stress effects simulated during an experimental tide indicated that enzymatic activities of this species are characterized by maximum expression related to an optimal salinity range (between 5 and 15 psu). Moreover, longer time exposure to various salinity tanks confirmed the effects of this factor on both AChE and GST activities. Therefore, optimal AChE activity was measured at 10 psu, while optimal GST activity was measured at 5 psu. Furthermore, significant effects of temperature were also recorded, particularly for AChE expression (slight effects were measured on GST expression) with an optimal condition at 11 degrees C. These experiments indicated a more pronounced effect of salinity over temperature especially on the AChE expression and confirmed the need to standardize sampling procedures in relation with environmental parameters for biomonitoring studies based on enzymatic analyses.     

Effect of Temperature, CO(2) Concentration, and Light Intensity on Oxygen Inhibition of Photosynthesis in Wheat Leaves

The effect of 21% O₂ and 3% O₂ on the CO₂ exchange of detached wheat leaves was measured in a closed system with an infrared carbon dioxide analyzer. Temperature was varied between 2° and 43°, CO₂ concentration between 0.000% and 0.050% and light intensity between 40 ft-c and 1000 ft-c. In most conditions, the apparent rate of photosynthesis was inhibited in 21% O₂ compared to 3% O₂. The degree of inhibition increased with increasing temperature and decreasing CO₂ concentration. Light intensity did not alter the effect of O₂ except at light intensities or CO₂ concentrations near the compensation point. At high CO₂ concentrations and low temperature, O₂ inhibition of apparent photosynthesis was absent. At 3% O₂, wheat resembled tropical grasses in possessing a high rate of photosynthesis, a temperature optimum for photosynthesis above 30°, and a CO₂ compensation point of less than 0.0005% CO₂. The effect of O₂ on apparent photosynthesis could be ascribed to a combination of stimulation of CO₂ production during photosynthesis, and inhibition of photosynthesis itself.     

The Neotropical Genus Notodiaptomus Kiefer, 1936 (Calanoida: Diaptomidae): Redescription of the Type Species Notodiaptomus deitersi (Poppe, 1891) and Designation of a Neotype

Ribautia williamsi sp. nov., a new dwarf geophilomorph centipede from the Lower Urubamba Region, Peruvian Amazonia, is described and illustrated based on the holotype female. The new species is characterized by having the coxal organs grouped in clusters (three of these in each coxopleuron of the ultimate leg-bearing segment) and ventral pore-fields present along all the body; these two combined traits being shared by five other Neotropical species currently included in the genus Ribautia Brölemann, 1909, i.e. R. centralis (Silvestri, 1907) (from Colombia and Brazil), R. difficilis Pereira, Minelli &; Barbieri, 1995 (from Brazil), R. montana Kraus, 1954 (from Peru), R. peruana (Verhoeff, 1941) (from Peru), and R. titicacae (Turk, 1955) (from Peru). The new taxon is differentiated from the aforementioned species by the low number of leg-bearing segments and small body length; it is included in a key which will enable the identification of all known Neotropical members having coxal organs grouped in clusters. R. williamsi sp. nov. is the 14th species of Ribautia recorded from Peru.

http://zoobank.org/urn:lsid:zoobank.org:pub:D9FA5FAF-7652-4A5B-AC09-8783F05A694D     

Naupliar development of Acanthodiaptomus denticornis (wierzejski, 1887) and Arctodiaptomus alpinus (Imhof, 1885) (Copepoda: Calanoida) and a comparison with other Diaptomidae

The six naupliar instars of the two alpine species Aconthodiaptornusdenticornis and Arctodiaptomus alpinus are described and illustrated.Their external morphology is compared with that of all presentlyknown diaptomid nauplii in an attempt to provide usehl taxonomiccharacteristics to identify larval diaptomids. The larval stagesof the two species are remarkably similar in size and overallappearance, and show an identical pattern of limb setation throughoutthe whole development. Diagnostic characters are mainly relatedto the differentiation of antennules and caudal armature.     

Effects of Salinity and Temperature on Survival and Reproduction of Boeckella hamata (Copepoda: Calanoida) from a Periodically Brackish Lake

The freshwater calanoid copepod, Boeckella hamata Brehm, occursperiodically in Lake Waihola, New Zealand, a shallow, tidally-influencedlake that experiences daily and seasonal fluctuations in salinity,and seasonal changes in temperature. To determine whether theseenvironmental changes might contribute to the copepod's disappearancefrom the lake in summer, we tested the survival and egg productionof B. hamata at a range of salinities (20-3000 mg^–1 Cl)and two temperatures (10°C, 20°C). Adults survived for20 days or more only at salinities     

A genetic determination of cryptic species (Copepoda: Calanoida) and their postglacial biogeography in North America

Allozyme electrophoresis of Hesperodiaptomus arcticus (Marsh) sensu lato at subarctic Churchill, Canada revealed significant deviations from random mating in several populations, as shown by the complete absence of certain heterozygous types. A broad geographic survey of 20 enzyme loci in 1077 individuals from 27 ponds at 11 arctic and alpine sites west of Hudson Bay demonstrated that there were three genetically distinct types. Morphological analysis of genetically classified populations uncovered consistent morphological differences that had been ignored previously. These morphological characteristics were used to reclassify preserved museum and private specimens from additional sites from the entire North American distribution of H. arcticus sensu lato. A detailed study of two of the distinct types co-occurring at Churchill showed reproduction timing and habitat differences consistent with reproductive isolation. I concluded that there are three species and each have different distributions. Most regions examined must have been repopulated by dispersal from glacial refugia after deglaciation. The nominal species is apparently restricted to western arctic localities in the vicinity of the Alaskan refugium while the other two putative taxa have dispersed widely into previously glaciated regions.     

First report of the presence of Acartia margalefi (Copepoda: Calanoida) in Southampton Water and Horsea Lake, UK

Acartia margalefi is recorded for the first time in Britishwaters, where it is found to be an important copepod in themesozooplankton community structure of Southampton Water andHorsea Lake. Within the genus Acartia. this species occurs allthrough the annual cycle. Abundance is higher in the upper estuary,where the range of temperature and salinity is relatively widerover the year. It is clear that A.margalefi is an estuarinespecies which can tolerate a significant range of temperature.     

Population Dynamics of Crustacean Zooplankton in a Mesotrophic Lake,with Emphasis on Boeckella hamata BREHM (Copepoda: Calanoida)

The crustacean zooplankton in Lake Mahinerangi, a polymictic, mesotrophic reservoir, were studied for 19 months. The cladocerans, Bosmina meridionalis and Ceriodaphnia dubia, had unimodal patterns of abundance with peak densities in summer; cyclopoids had a single peak of maximum abundance in autumn and Daphnia carinata showed a bimodal pattern with peak densities in early summer and early winter. The strong seasonality in abundance of zooplankton in Lake Mahinerangi distinguishes this lake from other temperate lakes in New Zealand and may reflect its cool winter temperatures (< 5 °C for 2 months). A calanoid, Boeckella hamata, bred throughout the year and was the dominant species numerically. Instar analysis indicated that there were at least three, and possibly four, generations per year. Instantaneous birth and death rates were low with annual mean values (0.036 and 0.057, respectively) that were 2-3.5 times less than those recorded in a population of the same species in Lake Pounui, but within the range of those recorded in calanoid populations elsewhere in New Zealand. The Boeckella population in Lake Mahinerangi appears to be controlled largely by temperature, parasitism and food, with predation having no, or a negligible, effect.     

Predation,competition, and co-occurrences of Boeckella and Calamoecia (Copepoda: Calanoida) in Western Australia

Patterns of co-occurrences of Boeckella and Calamoeciafound in Western Australia are documented. Patterns are analyzed inrelation to size of organisms and to geographical distributions oforganisms. Deviations from randomness in the number ofmulti-species assemblages suggest that biotic interactionsinfluence co-occurrences, but size relationships in severalco-occurring pairs indicate that competition for resources is nota factor influencing co-occurrence. Laboratory experimentsdemonstrate that the large Boeckella triarticulata consumesimmature stages of the small Calamoecia tasmanica butprovides a partial refuge for C. tasmanica when theplanktivorous fish Gambusia, which consumes Boeckellamore rapidly than Calamoecia, is present. These resultsindicate that co-occurrence patterns may be related to theintensity of predation by fish: in the absence of fish predation,Boeckella can prevent invasion of Calamoecia, whilemoderate predation by fish will reduce Boeckella density,consequently allowing Calamoecia to invade.     

Combined effects of temperature and food concentration on growth and reproduction of Eodiaptomus japonicus (Copepoda: Calanoida) from Lake Biwa (Japan)

相似文献   

Habitat Utilization and Depth Distribution of Small Cryptobenthic Fishes (Blenniidae, Gobiesocidae, Gobiidae, Tripterygiidae) in Ibiza (Western Mediterranean Sea)

The paper describes the habitat utilization of small cryptobenthic fishes of the families Blenniidae (Lipophrys nigriceps, and Parablennius zvonimiri), Gobiesocidae (Apletodon incognitus, Gouania wildenowi, Lepadogaster candollei, and L. lepadogaster), Gobiidae (Chromogobius zebratus, Corcyrogobius liechtensteini, Didogobius splechtnai, Gammogobius steinitzi, Millerigobius macrocephalus, Thorogobius ephippiatus, T. macrolepis, and Zebrus zebrus), and Tripterygiidae (Tripterygion melanurus). Nine different habitats from the waterline to a depth of about 40m were examined. The depth distributions of the single species and co-occurrences with other cryptobenthic fish species are given.     

Limnology of a Sewage Polluted Lake: The Lower Lake (Bhopal,India)

Seasonal and vertical distribution of temperature, pH, dissolved oxygen, free CO₂, alkalinity, nitrate, phosphate and phytoplankton have been studied at the deepest point of the Lower Lake, Bhopal from September 1979 to August 1981. Stratification was noticed in almost all the parameters. Bottom was frequently anoxic. The dominant groups among phytoplankton were Chlorophyceae, Cyanophyceae and Bacillariophyceae.     

Deep genetic divergences among morphologically similar and parapatric Skistodiaptomus (Copepoda: Calanoida: Diaptomidae) challenge the hypothesis of Pleistocene speciation

We used mitochondrial [cytochrome c oxidase subunit I (CO I ), cytochrome b , and 16S] and nuclear [internal transcribed spacer (ITS) phylogenies of Skistodiaptomus copepods to test hypotheses of Pleistocene divergence and speciation within the genus. Mitochondrial (mt)DNA sequence divergences do not support hypotheses for Pleistocene speciation and instead suggest much more ancient speciation events in the genus. Skistodiaptomus oregonensis and Skistodiaptomus pygmaeus (i.e. two morphologically similar and parapatric species) exhibited uncorrected mtDNA sequence divergences exceeding 20%. Similarly, we identified three divergent clades of Skistodiaptomus pallidus that exhibited mtDNA sequence divergences exceeding 15%, suggesting that even intraspecific divergence within this morphospecies predates the Pleistocene. We found clear evidence of CO I pseudogenes in S. pygmaeus , but their presence did not lead to significant overestimates of sequence divergences for this gene. Substitution saturation and strong purifying selection have most likely led to underestimates of sequence divergences and divergence times among Skistodiaptomus . The widespread phenomenon of morphological stasis among genetically divergent copepod groups indicates that speciation often occurs with little or no morphological change. Instead, morphological evolution may occur idiosyncratically after speciation and create discordant patterns of morphological similarity, shared ancestry and divergence time. Cryptic species complexes are therefore common in copepods, and morphological species concepts underestimate their true species diversity.  © 2009 The Linnean Society of London, Biological Journal of the Linnean Society , 2009, 96 , 150–165.     

Diel vertical migration by males,females, copepodids and nauplii in a limnetic population of diaptomus (Copepoda)

Diel vertical migration (DVM) by the sexes and life history stages of the copepod Diaptomus novamexicanus (Herrick) was investigated during two summers in a subalpine lake (Castle Lake, California, USA). Migratory behavior was quantified repeatedly by 1300 and 21–2200 hr sampling in the epilimnion. Population density and vertical distribution were estimated routinely at 1300 hr and at 2200 hr on selected dates. Males had greater night to day biomass differentials and ratios than females. The sexes showed comparable DVM participation (% of total biomass migrating) and amplitudes of migration (distance of ascent). Copepodids displayed higher participation, night/day ratios and amplitudes than younger copepods, but adult participation differed only from that of nauplii. Active participation in high amplitude ascents thus increased with age and was greatest in adult males. Analysis suggests that such relative behaviors probably occur in most limnetic Diaptomus, and that the magnitude of ascent into the epilimnion is associated with daytime vertical distribution.     

The effects of temperature and food on naupliar development,growth and metamorphosis in three species of Boeckella (Copepoda:Calanoida)

Three species of Boeckella (B. triarticulata, B. dilatata and B. hamata) were reared from hatching to copepodite I (CI) at three naturally fluctuating food levels and three temperatures in a 3 × 3 × 3 factorial design. Development times, lengths and mortality were measured for each species in nine treatments. Temperature had the major effect on development times but food level had the major effect on CI lengths. Mortality varied interspecifically with treatment. The combined effect of temperature and food on development times and lengths was species-specific. There were trade-offs between development time and growth to meet constraints imposed by naupliar metamorphosis. The three species varied in the timing of metamorphosis to CI. B. triarticulata nauplii were age determined, B. dilatata nauplii were size determined and B. hamata nauplii were flexibly age and size determined depending on treatment. Differences in life history parameters and the timing of naupliar metamorphosis are discussed in relation to the distributions of the species in ponds (B. triarticulata), glacial lakes (B. dilatata) and coastal lakes (B. hamata) in the South Island of New Zealand.