Permanent Pools Research Articles

Waterbirths: regional audit of infection control practices

Waterbirths are increasingly being offered as an option, although concerns about associated infection risks have been expressed. We undertook an audit of current practice in our region to help formulate an infection control policy. Questionnaires were sent to the Infection Control Nurses at 16 centres, with a request for completion in conjunction with the Infection Control Doctor. Fourteen (88%) centres responded, 11 of which carried out waterbirthing. Eight had permanent on-site pools, of which five were permanently plumbed in and provided with separate water inlets and outlets. All eight centres had infection control policies for waterbirthing. Six policies included care of the pool using detergent and disinfectant (chlorine-releasing compounds) and two using detergent alone. In none of the centres were the mothers tested for blood-borne viruses. Six centres collected data on infection in mother or child, and two carried out regular microbiological testing of pools. Infection control policies for waterbirths should include instructions for pool maintenance and decontamination, for prevention of legionella, for universal precautions and for use of personal protective equipment. Post-natal surveillance of mothers and babies is required in order to ascertain infection rates.

Comparison of processes regulating zooplankton assemblages in new freshwater pools

We compared the relative importance of colonization history to other known regulators of freshwater zooplankton assemblages (i.e. disturbance and nutrient enrichment) during this six-month study of initial colonization in artificial freshwater pools. We experimentally manipulated 16 small (1.5 m diameter) pools for permanence (permanent vs. temporary) and resource availability (± nitrogen & phosphorus). Nitrogen and phosphorus were added to high resource level pools in concentrations typical of eutrophic waters, while low resource level pools did not receive added nutrients. Permanent pools were maintained with added tap water and temporary pools dried out naturally for one month.

Distribution of aquatic macroinvertebrates within peatland pool complexes in the Flow Country, Scotland

Stationary water traps were used to sample the aquatic invertebrates from both shallow, drought-sensitive pools and deeper, more permanent pools on blanket bog in the Flow Country, northern Scotland during 1994–1995, an area important for nature conservation. The differences in numbers of invertebrates trapped, and the differences in species composition and abundance of adult aquatic Coleoptera and Hemiptera (the two most abundant groups caught) between these two pool types, and spatially within the deeper pools, were investigated.

Use of Habitats by Female Northern Pintails Wintering in Southwestern Louisiana

The breeding population of northern pintails (Anas acuta) in 1996 was 39% below the long-term average. Because winter habitat quality may influence subsequent breeding population size in pintails, identification of habitats used by wintering pintails and factors influencing use of habitats may be important for managing for population increase. We examined variation in diel use of habitats by radiotagged female pintails (n = 272) in southwestern Louisiana in relation to age (imm and ad), winter (1991-92 and 1992-93), and time period within winters (pre-hunting season, first hunting season, time between split hunting seasons, second hunting season, and post-hunting season). Diurnal use of refuges was significantly greater during hunting seasons than during immediately preceding or succeeding nonhunting seasons. Consequently, we reject Tamisier's (1976) hypothesis that high diurnal use of refuges by pintails in southwestern Louisiana occurs independent of hunting. Nocturnal use of refuges was low (<14%) during all time periods, and declined later in winters. Time-period differences in diurnal and nocturnal use of habitats (large permanent pools, marsh, rice, fallow [idle], and other agriculture [primarily soybeans]) were not consistent between winters. Diel use of refuges or habitats did not differ in relation to female age. Females used fallow and rice agriculture extensively, particularly at night, and these habitats collectively accounted for 68-93% of nocturnal use. Differential use of habitats between winters was related to annual differences in relative abundances of rice and fallow agriculture. Proximity of refuges to agricultural areas should be an important management consideration for wintering pintails and other waterfowl.

Survival of caddis larvae in relation to their case material in a group of temporary and permanent pools

1. The occurrence of larvae of Limnephiluscoenosus and L. vittatus (Trichoptera) was recorded in 103 rock pools both before and after the dry periods in spring–summer (April–May and July–early August), when a great number of the pools dried out. In early spring, 84% of the pools sampled contained larvae of at least one of the species. Limnephilus coenosus larvae were present in a higher proportion of pools that later dried out than in the permanent ones, while L. vittatus larvae were predominantly found in permanent pools. Larvae of both species were found together in 31% of the inhabited pools.2. Laboratory experiments, designed to elucidate differential survival under drought conditions, demonstrated that the organic cases of L. coenosus larvae held water more efficiently than did the mineral L. vittatus cases. Full‐grown (fifth instar) L. coenosus larvae also survived dry conditions better than did L. vittatus larvae. The higher survival of L. coenosus was due to a combination of drought‐resistant case material and a higher survival ability of the larvae themselves.3. Limnephilus vittatus larvae were restricted by their low capability to withstand desiccation, although case material and food were available for L. vittatus larvae in all pools. Absence of case material and high‐quality food in many pools, however, restricted the presence of L. coenosus larvae, but this species did not suffer from heavy mortality because of desiccation and all pool populations of L. coenosus survived until pupation.4. The differences in species composition in these temporary and permanent pools can be explained by the differential site selection by ovipositing females, as well as by larval survival. The intrinsically greater survival of L. coenosus larvae during drought, together with the water‐retaining properties of the cases, allowed this species to exploit stressful and risky habitats, such as temporary pools.

Development time and resistance to starvation of mosquito larvae

We evaluated a hypothesis on the existence of two ecological groups of mosquito larvae. One group inhabits bodies of water on the ground, such as ponds, ditches and marshes, and exhibits fast development and a limited ability to prolong development under feeding stress. The other group inhabits small containers such as leaf axils of plants, treeholes and man-made containers, and exhibits slower development and the ability to prolong immature development under feeding stress. We measured development time in larvae of 14 species of mosquitoes and resistance to starvation in 22 species of mosquitoes from Venezuela. They inhabited structures of six species of plants (phytotelmata), one type of artificial container, and two ground-water habitats. The ground-water mosquito larvae (from temporary and permanent pools) exhibited the fastest development and lowest resistance to starvation, as predicted. The phytotelm mosquitoes exhibited the slowest development and greatest resistance to starvation, with some excep...

Description of four new species in the hard coral genus Acropora Oken, 1815 (Scleractinia: Astrocoeniina: Acroporidae) from south-east Africa

Abstract Four new species in the hermatypic scleractinian coral genus Acropora are described from south-east Africa. Two species, A. natalensis sp. nov. and A. mossambica sp. nov., occur in both South Africa and Mozambique. Two species, A. sordiensis sp. nov., and A. branchi sp. nov., are only known from northern Natal in South Africa. A. branchi sp. nov. and A. mossambica sp. nov. are intertidal species and were collected from permanent tidal pools. A. sordiensis sp. nov. and A. natalensis sp. nov. are strictly subtidal species.

Description of four new species in the hard coral genus AcroporaOken, 1815 (Scleractinia: Astrocoeniina: Acroporidae) from south-east Africa

Four new species in the hermatypic scleractinian coral genus Acroporaare described from south-east Africa. Two species, A. natalensissp. nov. and A. mossambicasp. nov., occur in both South Africa and Mozambique. Two species, A. sordiensissp. nov., and A. branchisp. nov., are only known from northern Natal in South Africa. A. branchisp. nov. and A. mossambicasp. nov. are intertidal species and were collected from permanent tidal pools. A. sordiensissp. nov. and A. natalensissp. nov. are strictly subtidal species.

Fish populations in tropical floodplain pools: a re‐evalution of Holden's data on the River Sokoto

Abstract– In this study we asked whether the fish populations of residual pools in a seasonally fluctuating African river varied between years. We used a series of data on the fish of the permanent floodplain pools of the River Sokoto, Nigeria compiled by M. J. Holden (1963) to address this objective. Holden provided estimates for the size and biomass of fish populations in 12 permanent dry season pools over a period of 2 to 3 years. On average, only 22% of the species present in a pool were absent from that pool in the following sampling period. Despite low interannual variability in the species composition of the pools, rank correlation analysis indlcated significant variation in the relative numbers and biomass of the 10 most numerically abundant species in most pools. Altering the spatial scale of analysis to include all possible combinations of 2 and 6 pools did not affect the results. Indices of similarity also indicated relatively high annual variability in the relative abundance of species in the pool communities. We suggest that habitat selection may contribute to the continued occurrence of fish species in pools from year to year, and such factors as changes in the overall abundance of fish species in the system and haphazard trapping during flood decline may contribute to annual variation in their relative abundance.

The relationship between cavity-nesting birds and snags on clearcuts in western Oregon: B. Schreiber & D. S. deCalesta, Forest Ecology & Management, 50(3–4), 1992, pp 299–316

Liming experiments with powdered limestone (grain size < 3 mm) were conducted in eight acid shallow moorland pools in the Tongerense Heide heathland area from February 1988 until November 1989. The effects on water chemistry, diatoms and fungal infection of the eggs of the moor frog were studied. After an initial treatment in March 1988, the pH increased from c. 4·0 to c. 5·0 in those pools which dried out in summer and to c. 6·0 in the permanent pools. Alkalinity increased from 0 to 20–200 μeq litre−1 in temporary pools and from 0 to 300–500 μeq litre−1 in permanent pools. As drying out of the pools caused reacidification, after refilling the temporary pools were relimed in March 1989. No significant changes were found in concentrations of phosphate and nitrogen compounds. Eunotia paludosa, which is characteristic for ologotrophic, very acid pools and bogs with a fluctuating water table, was the dominant diatom in the untreated pools. It was replaced by eutraphentic and saprophilous taxa, particularly in the permanent pools. Species from extremely soft waters, which are very sensitive to acidification, were found only occassionally in some samples from the treated permanent pools. After liming the proportion of infected moor frog eggs decreased from c. 95% in the untreated to c. 5% in the treated pools.

Populations of larvae of anopheles spp. in natural breeding sites in western Venezuela, an area of refractory malaria.

Studies have been undertaken into on the diversity and relative abundance of larvae of Anopheles (Nyssorhynchus) spp. in 22 permanent or temporary pools in an area of 70 km2 in the eastern piedmont of the Venezuela Andes, between the mountains and the plains, an area in which malaria is refractory and A. nuñeztovari is present. Twelve species were identified, the most frequent, abundant and sympatric being A. triannulatus, A. albitarsis, A. nuñeztovari, A. oswaldoi and A. strodei. The samples from the permanent pools showed greater diversity of species and greater numbers of larvae than the samples from the temporary pools. The existence of the same larval associations in pools of other localities in the eastern piedmont of the Venezuelan Andes suggests the possibility of the making an ecological map of the breeding sites of A. nuñeztovari and for these anophelines in a region extending for 430 km.

Spatial and Temporal Variation in Wing Dimorphism of California Populations of the Waterstrider Aquarius remigis (Heteroptera: Gerridae)

Unlike those in northeastern North America, wing-dimorphic populations of California Aquarius remigis (Say) may contain relatively high frequencies of the macropterous morph. Winged individuals breed in seasonal streams, and apterous individuals are frequent in permanent streams and pools. The latter also harbor macropterous individuals during the summer dry season and support some breeding by them. Macropterous waterstriders are also common in permanent high-altitude streams of the Sierra Nevada. In California, winged individuals also fly readily before the breeding period, but they histolyze flight muscles at the beginning of the reproductive period suggesting that selection for migratory behavior in A. remigis affects only flights before reproduction. Temporary streams lack many waterstrider predators and other waterstrider species. These streams, however, run the risk of drying during development of nymphs. Only individuals with flight ability can colonize these habitats effectively and also escape when streams dry out.

Improvement of breeding success of the moor frog ( Rana arvalis) by liming of acid moorland pools and the consequences of liming for water chemistry and diatoms

Liming experiments with powdered limestone (grain size < 3 mm) were conducted in eight acid shallow moorland pools in the Tongerense Heide heathland area from February 1988 until November 1989. The effects on water chemistry, diatoms and fungal infection of the eggs of the moor frog were studied. After an initial treatment in March 1988, the pH increased from c. 4·0 to c. 5·0 in those pools which dried out in summer and to c. 6·0 in the permanent pools. Alkalinity increased from 0 to 20–200 μeq litre −1 in temporary pools and from 0 to 300–500 μeq litre −1 in permanent pools. As drying out of the pools caused reacidification, after refilling the temporary pools were relimed in March 1989. No significant changes were found in concentrations of phosphate and nitrogen compounds. Eunotia paludosa, which is characteristic for ologotrophic, very acid pools and bogs with a fluctuating water table, was the dominant diatom in the untreated pools. It was replaced by eutraphentic and saprophilous taxa, particularly in the permanent pools. Species from extremely soft waters, which are very sensitive to acidification, were found only occassionally in some samples from the treated permanent pools. After liming the proportion of infected moor frog eggs decreased from c. 95% in the untreated to c. 5% in the treated pools.

Geochemistry of Bolivian salars, Lipez, southern Altiplano: Origin of solutes and brine evolution

The southern Bolivian Altiplano is a volcanic area which contains numerous undrained basins occupied by playas and saline lakes, locally named salars. Solutes carried by springs and rivers into the salars originate mostly from the alteration of the volcanic rocks and the re-solution of ancient buried evaporites. Both weathering and hydrothermal alteration lead to Na-HCO 3 inflow waters of similar composition. High contents of lithium and boron are not specifically related to hydrothermal activity. Evaporite leaching leads to Na-Cl inflow waters of higher salinity. Atmospheric precipitation contributes only a small amount of Ca and SO 4, and very little Na or Cl. The calculated evaporative evolution of the inflow waters shows that about half of them should become highly alkaline brines and the other half should end as near-neutral brines. However, alkaline soda lakes are rare in this region. Most lake brines are of the Na-Cl and Na-Cl-(SO 4) types. To understand this anomaly one characteristic sequence of evaporating waters was studied in detail. Precipitation of calcite and Mg-smectites accounts only partially for the reduction of alkalinity. A further loss of alkalinity is probably related to the oxidation of wind-blown native sulfur in peripheral ponds. Wind-blown sulfur is also deposited around the lakes, on the drainage basins. In the rainy season, ephemeral streams carry along sulfur particles in permanent pools of the preconcentration areas. A hydrologic control of brine chemistry is suspected. Inflow waters, that should become alkaline, appear to evolve to neutral brines if they remain in contact with atmospheric dust and peripheral colluvium for a long time. On the contrary, inflow waters to soda lakes are generally close to the shore and have only minimal contact with atmospheric dust and peripheral sediments. Presently, all lakes are at relatively low levels, and inflow waters often drain an important area of the drainage basin before reaching the topographic low. In the past, lakes were at higher levels and less interaction occurred between inflow waters, atmospheric dust, and peripheral sediments. As a result, the chemistry of some lakes may have changed during the Quaternary.

Rain-pools on peat moorland as island habitats for midge larvae

A common aquatic habitat on peat moorland is a pool, often only a few centimetres deep. Many have a shorter average duration than that of the inhabitants but they are, nonetheless, inhabited by the larval stages of several chironomid species at moderately high densities. Because of their durational characteristics, these pools might be expected to have an endemic fauna, as is the case in similar ephemeral island habitats elsewhere. However, we find no such fauna. Indeed, we find no qualitative difference between them and permanent pools of the same substratum. We identify three reasons for the apparent absence of endemism. First, the midge fauna is able to survive dry periods in the moist mud, so that even the smallest pools are effectively permanent from the adaptive point of view. Second, although seasonal freezing eliminates the fauna of smaller pools, larvae are able to complete their development in the preceding summer. Third, nearby permanent pools which do not dry and in which the mud does not freeze, may act as refugia for re-invasion.

Factors affecting the distribution of the epiphytic fauna ofCorallina officinalls(L.) on an exposed rocky shore

Abstract The distribution of the red alga Corallina officinalis and the fauna associated with it have been investigated in permanent rock pools at Filey Brigg, North Yorkshire. The pools are all shallow and of an unusual shape, possessing a vertical rock step at the rear (southern) side, away from the direction of waves. All the organisms investigated showed evidence of being at least partly regulated in their density by physical variables, including depth of pool and frond density of C. officinalis. The most important single variable, however, was proximity to the rock step, or ‘back wall’, which in the case of the polychaete Spirorbis corallinae accounted for up to 68% of the observed variation in abundance.

Prediction of the Occurrence of Four Species of Mosquito Larvae with Logistic Regression on Water-chemistry Variables

Larvae of Anopheles punctipennis (Say), Culex territans Walker, Aedes atlanticus Dyar & Knab, and Psorophora ferox (von Humboldt) were collected and 13 water-chemistry variables were measured at permanent and semipermanent pools in Duplin County, N.C., during 1982 and 1983. Stepwise logistic regression was used to identify water-chemistry variables associated with habitats and to predict the occurrence of each species. Models based on pH and concentrations of Cl, K, and Na ions gave reasonable predictions of occurrence.

Modern pollen spectra from dakhleh oasis, western egyptian desert

Abstract The Dakhleh Oasis lies at the heart of the Western Egyptian Desert. Measurable precipitation occurs at rare intervals and the mean annual rainfall is <0.5 mm. Artesian water supports the pastoral agricultural economy of the oasis. The vegetation consists of fragmentary natural communities of Saharo-Arabian species and a predominant anthropogenic component. Twenty-five samples were analysed for modern pollen—5 Tauber traps placed in a horticultural station; 18 surface muds from permanent pools or ditches; and 2 relict pond sediments on the plateaux above the oasis depression. The Tauber trap spectra are dominated by local, introduced taxa, with small percentages (1–3) of long-distance (Mediterranean region) elements and Saharo-Arabian, native elements (0–2). The relict pond samples and to a lesser extent the ditch and pond muds contain constant though small percentages (5–7%) of native desert species of indicator value, large proportions of ubiquitous taxa (chiefly Cheno-Amaranth, Cyperaceae and Gramineae), smaller proportions of naturalized anemophilous trees (Casuarina and Eucalyptus), and scattered occurrences in low frequencies of such allochthonous, Mediterranean taxa as alder, birch, pine and oak.

The life histories of Limnephilus externus Hagen, Anabolia bimaculata (Walker), and Nemotaulius hostilis (Hagen) (Trichoptera, Limnephilidae) in a pond in southern Alberta, Canada

Limnephilus externus and Anabolia bimaculata are caddisflies that typically inhabit temporary pools, while Nemotaulius hostilis is a species that inhabits permanent pools. In a permanent pond with a fluctuating water level, both groups could be accommodated. The temporary-pool species laid egg masses on the ground above the water level in late summer. Larvae hatched in the autumn but remained in the masses until submersed by the rising water in the spring. Larvae grew at rates faster than those for any permanent-water trichopteran studied to date. Limnephilus externus adults emerged through August and underwent a 1-month reproductive delay. Anabolia bimaculata adults emerged through July, but showed no signs of a reproductive delay. By contrast, N. hostilis oviposited on riparian vegetation and larvae entered the water on hatching in August. Larval growth rates approximated those of other detritivorous shredders found in permanent waters. Over 75% of adult emergence occurred in 1 week at the end of May and adults underwent a reproductive diapause of slightly over a month's duration. The metabolic cost of high water temperatures on cool-adapted limnephilid caddisflies is postulated as the driving force behind the evolution of reproductive diapause in this family.

Limnological characteristics of a South Australian intermittent stream, Brown Hill Creek

Selected physicochemical features, litter input rates and the abundance and distribution of common invertebrates were studied in Brown Hill Creek, a small intermittent stream that flows annually for about 6 months near Adelaide, South Australia. Permanent pools had very highly coloured waters and long-term low oxygen levels in summer, apparently related to seasonality of litter inputs from Eucalyptus obliqua. The larvae of only two species of fully aquatic insect, Leptorussa darlingtoni and Lectrides varians (Trichoptera : Leptoceridae), remained in permanent pools once flow had ceased. A more diverse fauna, dominated by Riekoperla naso (Plecoptera : Gripopterygidae), was present during winter when the stream was flowing. Most of the more abundant insect species had extremely unusual life histories, including terrestrial egg deposition (Leptorussa darlingtoni and Lectrides varians), rapid larval growth at low temperatures (Riekoperla naso), and advanced ovoviviparity (Austrocerca tasmanica).