Carbon-14 Uptake by Picoplankton and Total Phytoplankton in Eight New Zealand Lakes

Eight New Zealand lakes were surveyed for ¹⁴C uptake by phytoplankton as a function of light intensity. The results support the view that the photosynthetic picoplankton is an important contributor to primary productivity in oligotrophic lakes but is relatively unimportant in more eutrophic lakes. A comparison of carbon uptake vs. light intensity characteristics (P vs. I) of the picoplankton size class vs. that of the total phytoplankton community supports the view that the picoplankton size class may be adapted to utilization of dimmer light.     

Chlorophyll-nutrient relationships in North Island lakes (New Zealand)

A model for the prediction of chlorophyll a in the near surface waters (1 m) of North Island lakes was developed using data from the literature and our own study of 12 North Island lakes. Annual geometric mean concentrations of chlorophyll a, total nitrogen and total phosphorus were used since no distinct growing season was discernable. Annual mean ratios of total nitrogen to total phosphorus in the near surface waters ranged between 10 and 59 (by weight). Strong correlations were obtained between log-transformed values of chlorophyll a and total nitrogen (r² = 0.53, n = 16), chlorophyll a and total phosphorus (r² = 0.71, n = 21), and between total nitrogen and total phosphorus (r² = 0.69, n = 16). However, after correcting for the high interdependency between total nitrogen and total phosphorus, only total phosphorus was found to be important in predicting chlorophyll concentrations. Much of the variance in the chlorophyll-phosphorus relation was attributable to differences in mean lake depth. Lakes with mean depths less than 11 m had significantly more chlorophyll a per unit of total phosphorus ( = 0.54 µg · µg^–1, SE = 0.05, n = 6) than lakes of greater mean depth ( = 0.17 µg · µg^–1, SE = 0.02, n = 14). When the effect of mean depth was taken into account, 89% of the variance in chlorophyll a was explained compared with 71% for the simple linear regression on total phosphorus alone.     

Seasonality in Nutrients and Phytoplankton Production in Two Shallow Lakes: Waigani Lake,Papua New Guinea,and Barton Broad,Norfolk, England

Waigani Lake, near Port Moresby, Papua New Guinea and Barton Broad, Norfolk, England are both shallow lakes nutrient-enriched from sewage effluent disposal. In Waigani Lake phytoplankton biomass varied seasonally with lower levels (100-200 mg chlorophyll α m⁻³) during the wet season increasing to over 400 mg chlorophyll α m⁻³ at the end of the dry season. Secchi disc depths varied between 0. 11 and 0. 34 m. Phytoplankton productivity in Waigani Lake was very high throughout the year (range: A_max 4,370-21,000 mg O₂ m⁻³ h⁻¹) but production was lower during the wet season (range: A_max 4,370-12,700 mg O₂ m⁻³ h⁻¹). High surface productivity was recorded from August to December except on sampling days when the weather was overcast. Productivity throughout the year declined rapidly with depth. Algal biomass in Barton Broad varied from 3-10 mg chlorophyll α m⁻³ in winter but increased in spring and was very high in summer (200-500 mg chlorophyll α m⁻³). Secchi disc depth varied from 0.21 m in August 1976 to 1.76 m in December. Phytoplankton production in Barton Broad was low in winter (range: A_max 247-1,250 mg O₂ m⁻³ h⁻¹) but increased markedly in spring and summer with the highest rate (A_max 6,850 mg O₂ m⁻³ h⁻¹) being recorded in August. Surface inhibition was observed during summer except when the weather was overcast. Seasonality in nutrients and phytoplankton in Waigani Lake appear to be related to rainfall. Nutrient concentrations in Barton Broad are more closely related to phytoplankton activity which, in turn, correlates with seasonality in solar radiation.     

New records of rotifers from the South Island lakes,New Zealand

Thirty-five lakes in the South Island of New Zealand were surveyed for rotifers during 1988–1991. Of 85 taxa identified, 31 are first records for New Zealand, bringing the rotifers recorded from the country to 331. Four species (Keratella australis, K. slacki, Lecane herzigi and L. tasmaniensis), previously recorded as endemic forms only in Australia, are now added to the New Zealand checklist. Several of the new records are photographed, and scanning electron micrographs of the trophi are shown. Comments are made on the Australasian endemics and rotifer biogeography in New Zealand.     

Epiphytic dinoflagellates in sub-tropical New Zealand,in particular the genus Coolia Meunier

Macroalgae growing in New Zealand's sub-tropical waters were sampled for epiphytic microalgae, in particular dinoflagellates. Four new Coolia isolates collected from sites throughout Northland in January/February 2013 were all identified as C. malayensis as determined by large subunit ribosomal DNA (LSU rDNA) sequence analysis and scanning electron microscopy. C. malayensis, a common dinoflagellate species in New Zealand, was previously reported as C. monotis and isolates held in the Cawthron Institute Culture Collection of Microalgae have now been reclassified based on the DNA sequence data. Toxicity studies of the New Zealand C. malayensis isolates (as determined by intraperitoneal (i.p.) injection of mice) resulted in an LD₅₀ of 80.0 mg/kg for isolate NLD 12 (95% CI: 63.8–101.0 mg/kg) compared to a Malaysian isolate which exhibited low toxicity, with transient effects at 900 mg/kg, but which resulted in the enlargement of the test animal's spleen. Ostreopsis siamensis, a common epiphytic bloom former in northern New Zealand, was found in association with Coolia at sites across Northland. Densest cell concentrations were collected from macroalgae throughout the Bay of Islands. Four new isolates of O. siamensis all produced palytoxin-like compounds (LC–MS analysis). Also isolated from Northland macroalgae were Amphidinium thermaeum (non-toxic by i.p. injection of mice) and Gambierdiscus cf. yasumotoi, with the latter producing a putative maitotoxin analogue (MTX-3) as determined by LC–MS.     

Phytoplankton as an Indicator of the Water Quality of the Deep Lakes South of the Alps

This paper offers a synoptic account of studies on the phytoplankton communities in the deep southern subalpine lakes (DSL) Garda, Iseo, Como, Lugano and Maggiore. The main cause of the degradation of the water quality in the DSL is eutrophication. The euphotic layers of these lakes are trophically different, ranging from the oligo-mesotrophy of lakes Maggiore and Garda to the meso-eutrophy of lakes Iseo and Lugano. The trophic status as estimated by using total phosphorus and chlorophyll a has provided consistent results in agreement with the models proposed by OECD (1982. Eutrophication of Waters. Monitoring, Assessment and Control, OECD, Paris). Though related with chlorophyll a and TP, the Secchi disk depths have significantly underestimated the trophic status of the DSL. Two trophic indices using the algal orders (PTI_orders) and species (PTI_species) were drawn up on the basis of the distribution of phytoplankton along a trophic gradient defined by the application of multivariate methods; the scores emerging from these indices were used to make a definitive ecological classification of water bodies on a scale from 1 to 5, in accordance with the Water Framework Directive. A third index (PTI_OE) was computed as the ratio between the annual mean values of the cumulative biovolumes of two groups of algal orders with opposite trophic characteristics. The three PTI indices were highly correlated, providing a consistent classification of the water bodies. The indices proposed in this work were specifically adopted for use in the DSL. However, the criteria for their implementation constitute a robust and impartial tool for assessing similar indices in other lake typologies and for evaluating the degree of specificity of the trophic indicator values assigned to the single phytoplankton orders and species.     

Phytoplankton succession in Lake Valencia,Venezuela

Phytoplankton counts and supporting physical and chemical data were taken on Lake Valencia, Venezuela, over a five-year interval. The data are used to test the validity of a successional paradigm for class-level taxa. According to the paradigm, formulated from previous studies of Lake Lanao, Philippines, and from data on temperate lakes, the order of taxa from early to late succession is: diatoms, chlorophytes, blue-green algae, dinoflagellates. A successional episode is considered to begin when stability of a water column is restored after deep mixing. As the episode progresses, there is a steady decrease in concentration of the limiting macronutrient (in this case, N). In a test of the validity of the paradigm for Lake Valencia, dates of exceptional population increase or decrease were obtained for each taxon. Since nitrate concentration declines steadily as succession progresses, the entry of a given taxon into the successional sequence is indicated quantitatively by the mean nitrate concentration on dates of exceptional increase in population density, and exit from the successional sequence is indicated by mean nitrate concentration on dates of exceptional population declines. The successional position of each major taxon, bounded by its entry and exit in the sequence, can be mapped on the complete spectrum of nitrate concentrations observed in the lake. For Lake Valencia, the nitrate mapping procedure agrees exactly with the predictions based on the successional paradigm. Conformance of Lake Valencia phytoplankton with predictions made a priori suggests that there is a generalized pattern in the phytoplankton succession of the mixed layers of temperate and tropical lakes.     

Macrophyte depth limits in North Island (New Zealand) lakes of differing clarity

The seasonal variation in water clarity, as indicated by the attenuation coefficient for photosynthetically active radiation, K _d (m^-1), was determined by monthly measurements for a year in 9 North Island, New Zealand lakes. K _d varied by a factor of 2 to 3 in 8 of the lakes, and a factor of 5 in one. Annual mean K _d (symbol% MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaam4saaaa!36BD!\[K\] _d) varied by a factor of approximately 15 between lakes. The maximum depth of water colonized by macrophytes (z _c)was also determined. Values of z _c were in the range 1.5–12.5 m. The relationship z _c =4.34/% MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaam4saaaa!36BD!\[K\]_d accounted for most (93 percent) of the variability in z _c , indicating that average annual clarity was probably a useful predictor of z _c in lakes in this region. The values of z _c in these North Island lakes were generally greater than values calculated using previously published empirical relationships derived for northern hemisphere groups of lakes. The extent to which these relationships underestimated z _c in the North Island lakes was broadly related to latitude. Estimated average irradiance at z _c in each lake was similar to compensation point irradiances reported previously for freshwater macrophytes.     

Late Quaternary paleoecology from fossil beetle communities in the Awatere Valley, South Island, New Zealand

Aim The research aim is to reconstruct last glacial maximum (LGM) and Holocene vegetation history and ecology from fossil beetle assemblages. Location The LGM and Holocene sites are located in the Awatere Valley, which lies in the tectonically active Marlborough Region in the north east of the South Island of New Zealand. Methods Beetle fossils were extracted from silty organic sediment using the standard kerosene flotation method. Fossils were identified by comparisons made to modern species based on morphology and surface features. The ecology and distribution of modern analogues are extrapolated to reconstruct the fossil environment. Results One hundred and forty‐five beetle species belonging to 33 families were identified. The LGM fossil fauna showed the local vegetation was characterized by a forest patch surrounded by an open tussock/grassland landscape. This Nothofagus (southern beech) forest persisted at the site until mid‐Holocene when it was replaced by a podocarp forest that contained high beetle diversity. Herbivores dominate in the early stage of this zone, indicating a relatively new forest environment. Later in the Holocene, the fauna is dominated by detritivores indicating an older more established forest. The late Holocene is characterized by low diversity and the absence of forest species. This fauna indicates that by 500 years ago, the forest was absent and is associated with an almost compete loss of beetle biodiversity. Main conclusions The fossil beetles provide a unique perspective into the past environment in the Awatere Valley on a local scale. The reconstruction supports regional pollen interpretations of Holocene vegetation by identifying a specific forest patch. Fossil beetles are thus a valuable local proxy for vegetation reconstructions.     

New species of Euptyctima (Acari,Oribatida) from New Zealand

Abstract

Oribotritia contortula n. sp., O. contraria n. sp., O. teretis n. sp., Rhysotritia bifurcata n. sp., Microtritia contraria n. sp., M. glabrata n. sp., Hoplophthiracarus bisulcus n. sp., Austrophthiracarus pulchellus n. sp., and Notophthiracarus claviger n. sp. are described from New Zealand.

The genera of Oribotritia Jacot, Rhysotritia Märkel & Meyer, Hoplophthiracarus Jacot, and Austrophthiracarus Balogh & Mahunka are new records for New Zealand.     

Fire and ice: volcanic and glacial impacts on the phylogeography of the New Zealand forest fern Asplenium hookerianum

In the Southern Hemisphere there has been little phylogeographical investigation of forest refugia sites during the last glacial. Hooker's spleenwort, Asplenium hookerianum, is a fern that is found throughout New Zealand. It is strongly associated with forest and is a proxy for the survival of woody vegetation during the last glacial maximum. DNA sequence data from the chloroplast trnL-trnF locus were obtained from 242 samples, including c. 10 individuals from each of 21 focal populations. Most populations contained multiple, and in many cases unique, haplotypes, including those neighbouring formerly glaciated areas, while the predominant inference from nested clade analysis was restricted gene flow with isolation by distance. These results suggest that A. hookerianum survived the last glacial maximum in widespread populations of sufficient size to retain the observed phylogeography, and therefore that the sheltering woody vegetation must have been similarly abundant. This is consistent with palynological interpretations for the survival in New Zealand of thermophilous forest species at considerably smaller distances from the ice sheets than recorded for the Northern Hemisphere. Eastern and central North Island populations of A. hookerianum were characterized by a different subset of haplotypes to populations from the remainder of the country. A similar east-west phylogeographical pattern has been detected in a diverse array of taxa, and has previously been attributed to recurrent vulcanism in the central North Island.     

Limnology and plankton periodicity of Jos Plateau water reservoir,Nigeria, West Africa

Limnological data (Dec. 1980–Jan. 1982) on the plankton and water chemistry of Lamingo Dam, located within the Jos biotite granite area of the Plateau State (Nigeria) are presented. The water-body falls in Beadle's (1981) category I of African lakes (conductivity < 40 µS cm^–1). Alkalinity (% MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGak0Jf9crFfpeea0xh9v8qiW7rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGabmiEayaara% aaaa!3914!\[\bar x\] = 0.3 meq l^–1), principally composed of bicarbonates, dominated the anions % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGak0Jf9crFfpeea0xh9v8qiW7rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaaK4waiaajI% eacaqIdbGaaK4tamaaxababaGaeyOeI0caleaacaaIZaaabeaakiaa% b6dacaqIdbGaaKiBaiaaj2cacaqG+aGaaK4uaiaaj+eadaqhaaWcba% GaaKinaaqaaiaajkdacaqITaaaaOGaaKyxaaaa!4657!\[\user1{[HCO}\mathop -\limits_3 {\text{ > }}\user1{Cl - }{\text{ > }}\user1{SO}_\user1{4}^{\user1{2 - }} \user1{]}\]The plankton were characterized by a moderate standing crop of phytoplankton, and zooplankton were, generally, very limited in species and abundance. The order of dominance for the categories of phyto and zooplankton was: [Bacillariophyceae > Chlorophyceae > Dinophyceae] and [Rotifera > Crustacea] respectively. A diel cycle was characterized by nocturnal upward migration of the zooplankton, and the reverse behaviour in the phytoplankton.Interrelations between the biotic assemblages of plankters and various physical and chemical variables are discussed.     

Stratigraphy of the fossil Chironomidae (Diptera) from Lake Grasmere,South Island,New Zealand,during the last 6000 years

The fossil chironomid fauna of a 3.26 m long sediment core from Lake Grasmere has been analysed. The fossil chironomid taxa belong mainly to the subgroups Tanytarsini, Orthocladiinae, Chironomini, and Tanyphodinae. Heptagyini and Podonominae were not common. Tanytarsini were the dominant component of the fauna with Corynocera sp. as the most abundant species during pre-Polynesian times (before 1000 yr BP). The abundance and the composition of the fossil chironomid taxa have fluctuated markedly over the last 6000 years. These fluctuations could be partly correlated with changes in the stratigraphy of the sediments in the core. Layers of highly minerogenic sediment contained the lowest numbers of remains whereas high abundances were found in the sections of the core with the greatest proportion of organic matter. It is suggested that major shifts in the structure of the chironomid community have been mainly caused by changes in the hydrology and inflows of the lake, and the rate and type of sedimentation, in addition to variations in lake productivity.     

Conservation status of New Zealand frogs, 2009

Abstract

A reappraisal of the conservation status of the New Zealand frog fauna is presented using the 2008 version of the New Zealand Threat Classification System. Of New Zealand's four extant endemic species, three are judged to be ‘Threatened’ (Leiopelma hamiltoni being ‘Nationally Critical’, and L. pakeka and L. archeyi being ‘Nationally Vulnerable’) and one ‘At Risk’ (L. hochstetteri ‘Declining’). Three Leiopelma species are listed as extinct—they are known from bone deposits in caves throughout the country until some time in the last 1000 years. Three introduced and naturalised Litoria species are abundant in New Zealand although two (L. aurea and L. raniformis) are threatened in their country of origin (Australia). An additional unidentified frog taxon from northern Great Barrier Island is listed as ‘Data Deficient’.     

Comparison of Plankton-Water Chemistry Relationships in Three Acid Stressed Lakes in Nova Scotia,Canada

A field program was conducted in 1980 and 1981 on three lakes in Kejimkujik National Park, Nova Scotia, to study plankton-water chemistry relationships in a region of potential acid precipitation stress. Among lake and between year comparisons were made. The three study sites represent two different types of lakes. Kejimkujik Lake (pH 4.8) and Pebbleloggitch Lake (pH 4.5) are both high-colored, dystrophic acid lakes. Beaverskin Lake is a clear, oligotrophic lake which is not as acidic (pH 5.4). The phytoplankton of Kejimkujik Lake was dominated by diatoms, while Pebbleloggitch Lake was dominated by chlorophytes and chrysophytes, and Beaverskin Lake was dominated by cyanophytes. Kejimkujik Lake had the highest total algal cell volume per liter, and Pebbleloggitch Lake the lowest. Rotifer populations composed the majority of the zooplankton communities, while the crustacean zooplankton were dominated by the acid-tolerant copepod Diaptomus minutus. Kejimkujik Lake had the lowest zooplankton biomass and Pebbleloggitch Lake the highest zooplankton biomass per m³. A pattern of highest algal density in Beaverskin Lake, but highest zooplankton density in Pebbleloggitch Lake emerged in both years. This is likely an effect of abundant, but unsuitable food (blue-green algae) in Beaverskin Lake and important detrital food resources in Pebbleloggitch Lake in both years. Multiple regression analysis of water chemistry variables with plankton species produced many significant effects, but failed to show clear patterns. Cause and effect relationships in aquatic ecosystems are poorly delineated by such techniques.     

New species of the genus Cyamops Melander from New Zealand (Diptera, Periscelididae, Stenomicrinae)

Two new species of the genus Cyamops (Diptera: Periscelididae), the first from New Zealand, are described. The two newly described species are: Cyamops alessandrae and Cyamops crosbyi. A key to the genera of the subfamily Stenomicrinae and to the species of Cyamops from the Australasian/Oceanian Region and detailed illustrations of structures of the male terminalia are provided.     

Water quality and plankton periodicity in two contrasting mine lakes in Jos,Nigeria

Water quality and plankton periodicity was studied in two mine lakes near Jos in the younger granite area of Plateau State, Nigeria. The investigation was carried out for 8 months. Transparency, pH and NO₃-N were significantly higher in Lake II while DOM, alkalinity, PO ₄ ^3– -P, BOD and chloride were significantly higher in Lake I. The order of dominance in Lake I was Bacillariophyceae, Cyanophyceae, Chlorophyceae and Dinophyceae while for Lake II; Chlorophyceae, Cyanophyceae, Bacillariophyceae and Dinophyceae. In Lake I the zooplankton in order of dominance were Cladocera, Rotifera, Copepoda, and nauplii and in Lake II Cladocera, Copepoda, Rotifera and nauplii. Although both lakes would seem unproductive based on the PO ₄ ^3– -P and NO ₃ ^– -N levels, Lake I appears more productive than Lake II.     

Phytoplankton dynamics in a shallow,hypertrophic reservoir (Lake Arancio,Sicily)

Phytoplankton abundance and composition in the hypertrophic man-made Lake Arancio was analyzed, based on a programme of weekly sampling from May 1990 to November 1991 and supported by measurements of limnological parameters. The highest value of phytoplankton biomass (78 mg l^–1) was observed in October 1990, during a bloom of the desmid Closterium limneticum var. fallax, while the lowest (0.15 mg l^–1) was measured in April 1991. During spring, autumn and winter 1990, species of the genus Closterium dominated the community, in the sequence: C. aciculare, C. limneticum var. fallax, C. limneticum. The summer community was more diverse with the predominance of organisms belonging to Chlorophyceae (Chlamydomonas, Eudorina, Coelastrum) and Cyanophyceae (Microcystis, Anabaena). In spring 1991, there was a long clear-water phase during which small green algae (Ankyra, Oocystis) and cryptomonads dominated. Subsequently, the summer season was characterized by a clear sequence of dominants, drawn, in turns, from species belonging to: Bacillariophyceae, Dinophyceae, Cyanophyceae, Euglenophyceae. The physics of the reservoir and its depth, owing to filling/draining constraints in a summer-arid climate, appeared to play a key role in the dynamics of phytoplankton community.     

Genetic divergences pre-date Pleistocene glacial cycles in the New Zealand speckled skink, Oligosoma infrapunctatum

Aim To examine the hypothesis raised by Graham S. Hardy that Pleistocene glacial cycles suffice to explain divergence among lineages within the endemic New Zealand speckled skink, Oligosoma infrapunctatum Boulenger. Location Populations were sampled from across the entire range of the species, on the North and South Islands of New Zealand. Methods We sequenced the mitochondrial genes ND2 (550 bp), ND4 + tRNAs (773 bp) and cytochrome b (610 bp) of 45 individuals from 21 locations. Maximum likelihood, maximum parsimony and Bayesian methods were used for phylogenetic reconstruction. The Shimodaira–Hasegawa test was used to examine hypotheses about the taxonomic status of morphologically distinctive populations. Results Our analysis revealed four strongly supported clades within O. infrapunctatum. Clades were largely allopatric, except on the west coast of the South Island, where representatives from all four clades were found. Divergences among lineages within the species were extremely deep, reaching over 5%. Two contrasting phylogeographical patterns are evident within O. infrapunctatum. Main conclusions The deep genetic divisions we found suggest that O. infrapunctatum is a complex of cryptic species which diverged in the Pliocene, contrary to the existing Pleistocene‐based hypothesis. Although Pleistocene glacial cycles do not underlie major divergences within this species, they may be responsible for the shallower phylogeographical patterns that are found within O. infrapunctatum, which include a radiation of haplotypes in the Nelson and Westland regions.