Persist or perish: critical life stages determine the sensitivity of invertebrates to disturbances
Lee, Gea H. van der; Kraak, Michiel H.S. ; Verdonschot, Ralf C.M. ; Verdonschot, Piet F.M. - \ 2020
Aquatic Sciences 82 (2020)2. - ISSN 1015-1621
Agapetus fuscipes - Bioassessment - Discharge - Life cycle - Lowland streams
A large proportion of studies assessing the impact of disturbances on the invertebrate community composition focus on a single life stage, assuming that those are an adequate indicator of environmental conditions. The effect of a specific disturbance may, however, depend on the life stage of the exposed organism. Therefore, we focused on the effect of spates on the caddisfly Agapetus fuscipes CURTIS (Trichoptera: Glossosomatidae) during different larval stages. A 2 year field study was performed in which we measured the discharge dynamics and population development of A. fuscipes in four lowland streams in The Netherlands. A stage-structured population model (i.e. StagePop) was used to test the impact of peak discharge on the different life stages, as larval instars 1–4 were not effectively sampled in the field. Four different mortality rates in response to spates were simulated, including a constant low, a constant high, a decreasing and an increasing impact per larval stage. This way, we were able to show a potential association between spates and population declines, where the stage-population model including decreasing impact by spates with increasing larval life stage most accurately described the population development of the larval instars 5–8. Focusing only on late instars could thus potentially result in underestimation of the effects of spates on this species. In conclusion, determination of responses of critical life stages to specific disturbances may help to identify the causes of the presence and absence of species, and thereby aid more effective management and restoration of degraded aquatic systems.
First evidence of a new spawning stock of Illex coindetii in the North Sea (NE-Atlantic)
Oesterwind, Daniel ; Bobowski, Bianca T.C. ; Brunsch, Anika ; Laptikhovsky, Vladimir ; Hal, Ralf Van; Sell, Anne F. ; Pierce, Graham J. - \ 2020
Fisheries Research 221 (2020). - ISSN 0165-7836
North Sea - ommastrephidae - illex - reproduction - distribution - Life cycle
Global changes drive abundance and distribution of species worldwide. It seems that at least some cephalopodstocks profit from global changes as indicated by increases in biomass and/or expansion of their geographicaldistribution, as appears to be the case for the commercially important ommastrephid squidIllexcoindetii, in theNorth Sea. Based on the recently increased abundance of this species seen in research trawl hauls, here wepresent the first evidence of a summer spawning stock ofIllexcoindetiiin the North Sea and derive a descriptionof its life cycle. Neither mated females nor spent males were reported from the area previously. In quarter 1 themajority ofIllexcoindetiiwere immature (maturity stage 0) and maturing (maturity stage 1–3) while in quarter 3almost exclusively mature and spent individuals (maturity stage 4–6) were caught. We observed up to threespermatangia bundles attached to females in quarter 3, indicating that spawning and reproduction takes place inthe North Sea and that the species is already established in this area. Estimated egg hatching dates suggest aprolonged hatching period and therefore likely a long spawning season, although cold temperature seems tolimit year round reproduction. The intensity of individual migrations from adjacent waters into the North Sea isunknown and therefore the number of individuals staying permanently in the North Sea could not be estimated.It is consequently still unclear whether the North Sea individuals ofI. coindetiiconstitute a new separate stock
Nitrogen flows in global pork supply chains and potential improvement from feeding swill to pigs
Uwizeye, Aimable ; Gerber, Pierre J. ; Opio, Carolyn I. ; Tempio, Giuseppe ; Mottet, Anne ; Makkar, Harinder P.S. ; Falcucci, Alessandra ; Steinfeld, Henning ; Boer, Imke J.M. de - \ 2019
Resources, Conservation and Recycling 146 (2019). - ISSN 0921-3449 - p. 168 - 179.
Animal production - Food wastes - Life cycle - Livestock - Nitrogen use efficiency
The global pork sector contributes to food security and supports livelihoods for millions of households but also causes nitrogen (N) pollution. Here we assess N flows, losses, and N use indicators for global pork supply chains, from “cradle-to-primary-processing-gate” and for three production systems: the backyard, intermediate and industrial systems. Subsequently, we evaluate the effects of feeding swill to industrial pigs on N flows and land use. To produce 3.5 Tg N of pork globally, 14.7 Tg N are lost into the environment, of which 68% is lost to watercourses in the form of nitrates and organic N and the reminder emitted to the atmosphere as N-gas (e.g., NH 3 , NOx and N2O). We found that the efficiency of N use, hotspot and magnitude of N losses per unit of area depend chiefly on the region (agro-ecological and economic context), origin of feed, and manure management systems. Swill feeding increases N use efficiency and reduces N losses at the feed production stage. It achieves a saving of 31 Mt of soybeans and 20 Mt of grains on dry matter basis, equivalent to 16 M ha of land used. Its adoption would require innovative policies to preserve food safety and public health. Future research may explore the feasibility and requirements to adopt swill feeding at a country level and may investigate potential impacts on other sustainability objectives.
An unusual sexual stage in the alkalophilic ascomycete Sodiomyces alkalinus
Kozlova, Maria V. ; Bilanenko, Elena N. ; Grum-Grzhimaylo, Alexey A. ; Kamzolkina, Olga V. - \ 2019
Fungal Biology 123 (2019)2. - ISSN 1878-6146 - p. 140 - 150.
Cytology - Development - Extremophile - Life cycle - Microscopy
Exploring life cycles of fungi is insightful for understanding their basic biology and can highlight their ecology. Here, we dissected the sexual and asexual life cycles of the obligate alkalophilic ascomycete Sodiomyces alkalinus that thrives at extremely high pH of soda lakes. S. alkalinus develops acremonium-type asexual sporulation, commonly found in ascomycetous fungi. However, the sexual stage was unusual, featuring very early lysis of asci which release young ascospores inside a fruit body long before its maturation. In a young fruit body, a slimy matrix which originates from the combined epiplasm of asci and united cytoplasm of the pseudoparenchymal cells, surrounds pooled maturing ascospores. Upon maturity, the ascospores are forcibly released through a crack in the fruit body, presumably due to an increased turgor pressure. These features of the sexual stage development resemble the ones found in unrelated marine fungi, indicating convergent evolution of the trait. We hypothesise these developmental features of S. alkalinus to be adaptive in the conditions of periodically inundated rims of soda lakes where the fungus thrives.
Unholy marriages and eternal triangles : How competition in the mushroom life cycle can lead to genomic conflict
Vreeburg, Sabine ; Nygren, Kristiina ; Aanen, Duur K. - \ 2016
Philosophical Transactions of the Royal Society B. Biological sciences 371 (2016)1706. - ISSN 0962-8436 - 10 p.
Basidiomycetes - Fungi - Genetic conflict - Life cycle - Mating system - Sex
In the vast majority of sexual life cycles, fusion between single-celled gametes is directly followed by nuclear fusion, leading to a diploid zygote and a lifelong commitment between two haploid genomes. Mushroom-forming basidiomycetes differ in two key respects. First, the multicellular haploid mating partners are fertilized in their entirety, each cell being a gamete that simultaneously can behave as a female, i.e. contributing the cytoplasm to a zygote by accepting nuclei, and a male gamete, i.e. only donating nuclei to the zygote. Second, after gamete union, the two haploid genomes remain separate so that the main vegetative stage, the dikaryon, has two haploid nuclei per cell. Only when the dikaryon produces mushrooms, do the nuclei fuse to enter a short diploid stage, immediately followed by meiosis and haploid spore formation. So in basidiomycetes, gamete fusion and genome mixing (sex) are separated in time. The ‘living apart together’ of nuclei in the dikaryon maintains some autonomy for nuclei to engage in a relationship with a different nucleus.We show that competition among the two nuclei of the dikaryon for such ‘extramarital affairs’ may lead to genomic conflict by favouring genes beneficial at the level of the nucleus, but deleterious at that of the dikaryon.