Responses and structural recovery of periphytic diatom communities after short-term disturbance in some rivers (Hanoi, Vietnam)

Abstract. The need to acquire a representative periphytic diatom sample for river water quality monitoring has been recognised in the development of existing diatom indices, important in the development and employment of diatom monitoring tools for the Water Framework Directive. In this study, a nested design with replication is employed to investigate the magnitude of variation in diatom biomass, composition and Trophic Diatom Index at varying scales within a small chalk river. The study shows that the use of artificial substrates may not result in diatom communities that are typical of the surrounding natural substrates. Periphytic diatom biomass and composition varies between artificial and natural substrates, riffles and glides and between two stretches of the river channel. The study also highlights the existence of high variation in diatom frustule frequency and biovolume at the individual replicate scale which may have implications for the use of diatoms in routine monitoring.

Download Full-text

Response of periphytic diatom communities to multiple stressors influencing lakes in the Muskoka River Watershed, Ontario, Canada

Freshwater Science ◽

10.1086/690144 ◽

2017 ◽

Vol 36 (1) ◽

pp. 77-89 ◽

Cited By ~ 3

Author(s):

Mark J. MacDougall ◽

Andrew M. Paterson ◽

Jennifer G. Winter ◽

F. Chris Jones ◽

Lillian A. Knopf ◽

...

Keyword(s):

Multiple Stressors ◽

River Watershed ◽

Diatom Communities ◽

Periphytic Diatom

Download Full-text

Effects of the phenylurea herbicide isoproturon on periphytic diatom communities in freshwater indoor microcosms

Environmental Pollution ◽

10.1016/s0269-7491(96)00080-2 ◽

1996 ◽

Vol 94 (2) ◽

pp. 141-152 ◽

Cited By ~ 53

Author(s):

F. Pérès ◽

D. Florin ◽

T. Grollier ◽

A. Feurtet-Mazel ◽

M. Coste ◽

...

Keyword(s):

Phenylurea Herbicide ◽

Diatom Communities ◽

Periphytic Diatom

Download Full-text

Temporary effect of chiseling on the compaction of a Rhodic Hapludox under no-tillage

Revista Brasileira de Ciência do Solo ◽

10.1590/s0100-06832012000200024 ◽

2012 ◽

Vol 36 (2) ◽

pp. 547-555 ◽

Cited By ~ 18

Author(s):

Sâmala Glícia Carneiro Silva ◽

Álvaro Pires da Silva ◽

Neyde Fabíola Balarezo Giarola ◽

Cássio Antônio Tormena ◽

João Carlos de Moraes Sá

Keyword(s):

Physical Properties ◽

Bulk Density ◽

Soil Physical Properties ◽

No Tillage ◽

Short Term ◽

Wetting And Drying ◽

Soil Layers ◽

Structural Recovery ◽

One Year ◽

High Degree

Mechanical chiseling has been used to alleviate the effects of compaction in soils under no-tillage (NT). However, its effect on the soil physical properties does not seem to have a defined duration period. The purpose of this study was to evaluate the behavior of the bulk density (BD) and degree of compaction (DC) at different soil depths, after chiseling in no-tillage, for one year. The experiment was performed in Ponta Grossa, Paraná State, Brazil, using an Oxisol (Rhodic Hapludox). Bulk density and DC were previously measured in an area under NT for 16 years, then immediately after chiseling (CHI) in May 2009, six months after chiseling (CHI6M) in October 2009 and one year after chiseling (CHI12M) in May 2010. In the layers 0.0-0.10, 0.10-0.20 and 0.20-0.30 m, there was a significant BD reduction CHI and a marked increase CHI6M. The BD values measured CHI12M were similar to those before tillage. Chiseling reduced the DC in the layers 0.0-0.10 m and 0.10-0.20 m, but returned to the initial values one year later. During the evaluation periods CHI, CHI6M and CHI12M, the BD increased in the layer 0.30-0.40 m, compared with NT. The highest DC values were observed six months after chiseling; nevertheless the structural recovery of the soil was considerable, possibly due to the high degree of soil resilience and the influence of the wetting and drying cycles detected in the study period. The chiseling effects, evaluated by BD and DC, lasted less than one year, i.e., the beneficial short-term effects of chiseling on the reduction of the surface BD increased the risk of compaction in deeper soil layers.

Download Full-text

Fauna and vegetation responses to fire and invasion by toxic cane toads (Rhinella marina) in an obligate seeder-dominated tropical savanna in the Kimberley, northern Australia

Wildlife Research ◽

10.1071/wr14259 ◽

2015 ◽

Vol 42 (4) ◽

pp. 302 ◽

Cited By ~ 6

Author(s):

Ian J. Radford ◽

Richard Fairman

Keyword(s):

Vegetation Change ◽

Fire Regimes ◽

Ground Layer ◽

Cane Toad ◽

Short Term ◽

Rhinella Marina ◽

Structural Recovery ◽

Invasion Impacts ◽

Riparian Habitats ◽

Large Predators

Context Changed fire regimes are an important threatening process to savanna biodiversity. Fire-sensitive vegetation such as pindan and its fauna may be particularly susceptible to fire impacts. Invasion by alien species is an additional threatening process. The toxic anuran Rhinella marina is a well publicised invader of savannas. Little is known of impacts in many habitats. Aims To test the hypotheses (1) that fire responses among pindan fauna are greater than general savanna responses, and (2) that cane toad-invasion impacts will be reduced relative to riparian habitats. Methods Reptiles, frogs, invertebrates and mammals were surveyed seven times from 2008 to 2012, four times before and three times following R. marina invasion. Time since last fire was recorded during each survey. Vegetation change was measured. Key results Pindan vegetation structural recovery took 4–5 years, whereas fauna recovery took only 1 year. Ground active agamids, combined Scincidae, fossorial skinks and ground-layer invertebrates responded positively to recent fire. Skinks of Ctenotus spp. declined in size after fire. Short-term fauna responses reflect rapid re-establishment of herbaceous cover. Fauna responses were detected following R. marina invasion, including increases in frogs of Uperoleia spp. and skinks of Carlia spp., and decreases in Lerista griffini and ground-layer invertebrates. Insufficient data were available to test for responses among large predators; however, >50% lower Varanus spp. trap success occurred post-invasion. No invasion response was detected among small mammals. Conclusions Pindan fauna fire responses were similar to those of savannas. Fauna responses to Rhinella marina invasion were relatively minor compared with those previously reported in riparian habitats and this may be related to the lower abundance of the invader here than in previous studies in riparian or more fertile habitats. Implications The dominant obligate seeding tree in pindan woodland, A. tumida, requires >4 years with no high-intensity fires for re-establishment of the dominant tree. Fire management should aim to minimise extensive fires to reduce impacts on fire-sensitive fauna. Persistence of large predators after cane-toad invasion suggests possible refuge value of low-productivity pindan savannas.

Download Full-text