32 research outputs found
Biodiversity patterns of wetland macroinvertebrate assemblages in the South-Western Cape, South Africa
Includes bibliographical references (p. 98-108).Despite the recent surge in interest in wetland invertebrates, given their immediate importance in overall wetland functioning, these studies have largely been conducted in the northern hemisphere and very little is known in South Africa. In order to fill this knowledge vacuum, this study was conducted to investigate biodiversity patterns of wetland macro invertebrates assemblages in the south-western Cape, South Africa. 140 wetlands were sampled in four geographic clusters, the Cape Flats, the West Coast, the Cederberg and the Agulhas Plain. Open-water, submerged vegetation and emergent vegetation habitats were sampled separately using a square-framed sweep net with a 23.5cm mouth and 80l1m mesh and physico-chemical attributes measured at each site. A total of 126 taxa emanating from more than 26 000 individuals representing 73 genera and 51 families was recorded. Currently, five species new to science were also discovered, three from Hydraenidae (Prosthetops sp. nov, Parhydraena sp. nov and Mesoceration repandum Perkins, 2009), Hydryphantidae (Hydryphanres sp. nov) and Streptocephalidae (Streptocephalus sp. nov). However, all of these new species but one were recorded from single location, suggesting that they might be rare or unique. Richness estimators predicted true taxon richness at about 20-47 taxon more than the observed taxon richness. The high number of uniques and singletons, as well as the Incidence-based Coverage Estimator, suggest that sampling was not adequate to capture the full biodiversity suite. However, I believe this is not necessarily true and this is discussed in detailed in the discussion. The sub-area Cederberg was found to be the biologically richest area, with the three of the new species recorded there. A significant difference was observed in relative abundance (RA) and frequency of occurrence between open-water habitat and vegetated habitats (submerged and emergent vegetation). On the other hand, a significant difference was not found between wetlands with different number of habitat types. No appreciable congruence was seen between different taxonomic groups (i.e. at order and family level) themselves, suggesting that neither can be used as a surrogate for the others. However, predators - which by the way had the highest frequency of occurrence and 2nd highest relative abundance after gatherers - were strongly correlated with overall assemblage and Hemiptera. In addition, together with Hemiptera they had â„75% similarity with the overall assemblage, suggesting that they are fairly good surrogates for overall assemblage. These results are quite promising especially for biomonitoring programmes and warrant further research. Environmental variables contributed significantly higher in explaining assemblage composition, and the model containing pH, Phosphate, conductivity, turbidity and ammonium was found to explain significant variation in macro invertebrate assemblage
Protected and un-protected urban wetlands have similar aquatic macroinvertebrate communities: a case study from the Cape Flats Sand Fynbos region of southern Africa
Rapid urbanisation has led to major landscape alterations, affecting aquatic ecosystemsâ hydrological and biogeochemical cycles, and biodiversity. Thus, habitat alteration is considered a major driver of aquatic biodiversity loss and related aquatic ecosystem goods and services. This study aimed to investigate and compare aquatic macroinvertebrate richness, diversity and community structure between urban temporary wetlands, located within protected and un-protected areas. The latter were found within an open public space or park with no protection or conservation status, whereas the former were inaccessible to the public and had formal protected, conservation status
Elucidating the structural properties of gold selenide nanostructures
Please read abstract in the article.Mintek and NRFhttp://rsc.li/njc2020-03-14hj2020Physic
Freshwater mussel conservation: A global horizon scan of emerging threats and opportunities
We identified 14 emerging and poorly understood threats and opportunities for addressing the global conservation of freshwater mussels over the next decade. A panel of 17 researchers and stakeholders from six continents submitted a total of 56 topics that were ranked and prioritized using a consensus-building Delphi technique. Our 14 priority topics fell into five broad themes (autecology, population dynamics, global stressors, global diversity, and ecosystem services) and included understanding diets throughout mussel life history; identifying the drivers of population declines; defining metrics for quantifying mussel health; assessing the role of predators, parasites, and disease; informed guidance on the risks and opportunities for captive breeding and translocations; the loss of mussel-fish co-evolutionary relationships; assessing the effects of increasing surface water changes; understanding the effects of sand and aggregate mining; understanding the effects of drug pollution and other emerging contaminants such as nanomaterials; appreciating the threats and opportunities arising from river restoration; conserving understudied hotspots by building local capacity through the principles of decolonization; identifying appropriate taxonomic units for conservation; improved quantification of the ecosystem services provided by mussels; and understanding how many mussels are enough to provide these services. Solutions for addressing the topics ranged from ecological studies to technological advances and socio-political engagement. Prioritization of our topics can help to drive a proactive approach to the conservation of this declining group which provides a multitude of important ecosystem services.This publication is based upon work from COST Action CA18239, supported by COST (European Cooperation in Science and Technology). DCA was supported by Corpus Christi College and a Dawson Fellowship at St. Catharine's College, Cambridge. MLL was supported by FCT-Fundacao para a Ciencia e a Tecnologia (2020.03608.CEECIND). ISO was supported by a Whitten Studentship. INB was supported by the Russian Science Foundation (grant no. 21-17-00126). YVB was supported by RSF project no. 21-14-00092. KD was supported by the Czech Science Foundation (19-05510 S). TZ was supported by statutory funds of IOP PAN. MK was supported by funding through the Australian National Environmental Science Program. For the purpose of open access, the author has applied a Creative Commons Attribution (CC BY) licence to any Author Accepted Manuscript version arising from this submission
Deeper knowledge of shallow waters: reviewing the invertebrate fauna of southern African temporary wetlands
Temporary lentic wetlands are becoming
increasingly recognised for their collective role in
contributing to biodiversity at the landscape scale. In
southern Africa, a region with a high density of such
wetlands, information characterising the fauna of
these systems is disparate and often obscurely published.
Here we provide a collation and synthesis of
published research on the aquatic invertebrate fauna
inhabiting temporary lentic wetlands of the region. We
expose the poor taxonomic knowledge of most groups,
which makes it difficult to comment on patterns of
richness and endemism. Only a few groups (e.g. large
branchiopods, ostracods, copepods and cladocerans)
appear to reach higher richness and/or endemicity in
temporary wetlands compared to their permanent
wetland counterparts. IUCN Red List information is
lacking for most taxa, thus making it difficult to
comment on the conservation status of much of the
invertebrate fauna. However, except for a few specialist
groups, many of the taxa inhabiting these
environments appear to be habitat generalists that
opportunistically exploit these waterbodies and this is hypothesised as one of the reasons why endemism
appears to be low for most taxa. Given that taxonomy
underpins ecology, the urgent need for more foundational
taxonomic work on these systems becomes
glaringly apparent
The role of anthropogenic habitats in freshwater mussel conservation
Anthropogenic freshwater habitats may provide undervalued prospects for long-term conservation as part of species conservation planning. This fundamental, but overlooked, issue requires attention considering the pace that humans have been altering natural freshwater ecosystems and the accelerated levels of biodiversity decline in recent decades. We compiled 709 records of freshwater mussels (Bivalvia, Unionida) inhabiting a broad variety of anthropogenic habitat types (from small ponds to large reservoirs and canals) and reviewed their importance as refuges for this faunal group. Most records came from Europe and North America, with a clear dominance of canals and reservoirs. The dataset covered 228 species, including 34 threatened species on the IUCN Red List. We discuss the conservation importance and provide guidance on how these anthropogenic habitats could be managed to provide optimal conservation value to freshwater mussels. This review also shows that some of these habitats may function as ecological traps owing to conflicting management practices or because they act as a sink for some populations. Therefore, anthropogenic habitats should not be seen as a panacea to resolve conservation problems. More information is necessary to better understand the trade-offs between human use and the conservation of freshwater mussels (and other biota) within anthropogenic habitats, given the low number of quantitative studies and the strong biogeographic knowledge bias that persists.This publication is based upon work from COST Action CA18239,
supported by COST (European Cooperation in Science and
Technology). A.M.L. was financed by the Institute of Environmental
Sciences Jagiellonian University (N18/DBS/000003) and K.N.
by the AragĂłn Government. The authors acknowledge JarosĆaw
Andrzejewski, Bartosz Czader, Anna Fica, Marcin Horbacz,
Tomasz Jonderko, Steinar KÄlÄs, Tomasz Kapela, BjÞrn Mejdell
Larsen, Maciej Pabijan, Katarzyna Pawlik, Ilona PopĆawska, Joanna
Przybylska, Tomasz PrzybyĆ, Mateusz Rybak, Kjell Sandaas, JarosĆaw
SĆowikowski, Tomasz Szczasny, MichaĆ Zawadzki and PaweĆ Zowada
for providing detailed information on specific examples concerning
freshwater mussels in anthropogenic habitats. We thank the editor
and two anonymous referees for the valuable suggestions made,
which increased the clarity of our manuscript.info:eu-repo/semantics/publishedVersio
Simulating rewetting events in intermittent rivers and ephemeral streams: a global analysis of leached nutrients and organic matter
Climate change and human pressures are changing the global distribution and extent of intermittent rivers and ephemeral streams (IRES), which comprise half of the global river network area. IRES are characterized by periods of flow cessation, during which channel substrates accumulate and undergo physicoâchemical changes (preconditioning), and periods of flow resumption, when these substrates are rewetted and release pulses of dissolved nutrients and organic matter (OM). However, there are no estimates of the amounts and quality of leached substances, nor is there information on the underlying environmental constraints operating at the global scale. We experimentally simulated, under standard laboratory conditions, rewetting of leaves, riverbed sediments, and epilithic biofilms collected during the dry phase across 205 IRES from five major climate zones. We determined the amounts and qualitative characteristics of the leached nutrients and OM, and estimated their areal fluxes from riverbeds. In addition, we evaluated the variance in leachate characteristics in relation to selected environmental variables and substrate characteristics. We found that sediments, due to their large quantities within riverbeds, contribute most to the overall flux of dissolved substances during rewetting events (56â98%), and that flux rates distinctly differ among climate zones. Dissolved organic carbon, phenolics, and nitrate contributed most to the areal fluxes. The largest amounts of leached substances were found in the continental climate zone, coinciding with the lowest potential bioavailability of the leached organic matter. The opposite pattern was found in the arid zone. Environmental variables expected to be modified under climate change (i.e. potential evapotranspiration, aridity, dry period duration, land use) were correlated with the amount of leached substances, with the strongest relationship found for sediments. These results show that the role of IRES should be accounted for in global biogeochemical cycles, especially because prevalence of IRES will increase due to increasing severity of drying events
Slaughter weight rather than sex affects carcass cuts and tissue composition of Bisaro pigs
Carcass cuts and tissue composition were assessed in Bisaro pigs (n=64) from two sexes (31 gilts and 33 entire
males) reared until three target slaughter body-weights (BW) means: 17 kg, 32 kg, and 79 kg. Dressing percentage
and backfat thickness increased whereas carcass shrinkage decreased with increasing BW. Slaughter
weight affected most of the carcass cut proportions, except shoulder and thoracic regions. Bone proportion
decreased linearly with increasing slaughter BW, while intermuscular and subcutaneous adipose tissue depots
increased concomitantly. Slaughter weight increased the subcutaneous adipose tissue proportion but this impaired
intramuscular and intermuscular adipose tissues in the loin primal. The sex of the pigs minimally affected
the carcass composition, as only the belly weight and the subcutaneous adipose tissue proportions were greater
in gilts than in entire males. Light pigs regardless of sex are recommended to balance the trade-offs between
carcass cuts and their non-edible compositional outcomes.Work included in the Portuguese PRODER research Project
BISOPORC â Pork extensive production of BĂsara breed, in two alternative
systems: fattening on concentrate vs chesnut, Project PRODER SI
I&DT Medida 4.1 âCooperação para a Inovaçãoâ. The authors are
grateful to Laboratory of Carcass and Meat Quality of Agriculture
School of Polytechnic Institute of Bragança âCantinho do Alfredoâ. The
authors are members of the MARCARNE network, funded by CYTED
(ref. 116RT0503).info:eu-repo/semantics/publishedVersio
Simulating rewetting events in intermittent rivers and ephemeral streams: A global analysis of leached nutrients and organic matter
Climate change and human pressures are changing the global distribution and the exâ
tent of intermittent rivers and ephemeral streams (IRES), which comprise half of the
global river network area. IRES are characterized by periods of flow cessation, during
which channel substrates accumulate and undergo physicoâchemical changes (preconâ
ditioning), and periods of flow resumption, when these substrates are rewetted and
release pulses of dissolved nutrients and organic matter (OM). However, there are no
estimates of the amounts and quality of leached substances, nor is there information
on the underlying environmental constraints operating at the global scale. We experiâ
mentally simulated, under standard laboratory conditions, rewetting of leaves, riverâ
bed sediments, and epilithic biofilms collected during the dry phase across 205 IRES
from five major climate zones. We determined the amounts and qualitative characterâ
istics of the leached nutrients and OM, and estimated their areal fluxes from riverbeds.
In addition, we evaluated the variance in leachate characteristics in relation to selected
environmental variables and substrate characteristics. We found that sediments, due
to their large quantities within riverbeds, contribute most to the overall flux of disâ
solved substances during rewetting events (56%â98%), and that flux rates distinctly
differ among climate zones. Dissolved organic carbon, phenolics, and nitrate contribâ
uted most to the areal fluxes. The largest amounts of leached substances were found
in the continental climate zone, coinciding with the lowest potential bioavailability of
the leached OM. The opposite pattern was found in the arid zone. Environmental variâ
ables expected to be modified under climate change (i.e. potential evapotranspiration,
aridity, dry period duration, land use) were correlated with the amount of leached subâ
stances, with the strongest relationship found for sediments. These results show that
the role of IRES should be accounted for in global biogeochemical cycles, especially
because prevalence of IRES will increase due to increasing severity of drying event