Search results for "freshwater"
showing 10 items of 285 documents
Long-term recovery of stream habitat structure and benthic invertebrate communities from in-stream restoration
2002
Headwater streams channelized for water transport of timber in Finland are being restored to their pre-channelization state. The primary motivation is the enhancement of sport fisheries, but restoration probably has profound impacts also on other stream organisms. We assessed how such ‘‘single-goal’’ restorations affect benthic macroinvertebrate communities. We revisited the streams sampled by Laasonen et al. [Aquatic Conservation: Marine and Freshwater Ecosystems 8 (1998)] in the early 1990s when the streams had been recently restored. In 1997, the recovery period of these streams ranged from 4 to 8 years. Habitat structure among the stream types represented a distinct recovery gradient, w…
Reto un izzūdošo Latvijas savvaļas orhideju bioloģiskās īpatnības in situ un in vitro
2012
Promocijas darbs (publikāciju kopa) tika izstrādāts V/a „Nacionālais Botāniskais dārzs Augu valsts bioloģiskās daudzveidības in vitro saglabāšanas nodaļā laika posmā no 2008. līdz 2011. gadam. Ģenētiskie pētījumi tika veikti LU Bioloģijas institūta Augu Ģenētikas laboratorijā 2010. un 2012. gadā.
Carotenoid-based colour of acanthocephalan cystacanths plays no role in host manipulation.
2009
Manipulation by parasites is a catchy concept that has been applied to a large range of phenotypic alterations brought about by parasites in their hosts. It has, for instance, been suggested that the carotenoid-based colour of acanthocephalan cystacanths is adaptive through increasing the conspicuousness of infected intermediate hosts and, hence, their vulnerability to appropriate final hosts such as fish predators. We revisited the evidence in favour of adaptive coloration of acanthocephalan parasites in relation to increased trophic transmission using the crustacean amphipodGammarus pulexand two species of acanthocephalans,Pomphorhynchus laevisandPolymorphus minutus. Both species show car…
Conservation status of the Hispaniolan Slider, Trachemys decorata, at Lake Trou Caïman, eastern Haiti: first data on an endemic, poorly studied, and …
2022
Hispaniolan Slider (Trachemys decorata) is a freshwater turtle of conservation interest, endemic to the island of Hispaniola. Although the species is known to be threatened with habitat destruction, hybridization with congeneric species, and commercial harvesting, little information is available on natural populations. Here we report the results of a pilot study conducted at Lake Trou Caiman, Haiti. From October 2017 to February 2018, we captured 44 individuals (mostly in areas dominated by cattails, Typhaceae) and had access to 48 additional individuals held in captivity by fishers and local people. Captive individuals were significantly larger than wildcaught ones. Based on individuals wi…
Widespread diminishing anthropogenic effects on calcium in freshwaters
2019
Calcium (Ca) is an essential element for almost all living organisms. Here, we examined global variation and controls of freshwater Ca concentrations, using 440 599 water samples from 43 184 inland water sites in 57 countries. We found that the global median Ca concentration was 4.0 mg L−1 with 20.7% of the water samples showing Ca concentrations ≤ 1.5 mg L−1 , a threshold considered critical for the survival of many Ca-demanding organisms. Spatially, freshwater Ca concentrations were strongly and proportionally linked to carbonate alkalinity, with the highest Ca and carbonate alkalinity in waters with a pH around 8.0 and decreasing in concentrations towards lower pH. However, on a temporal…
Biological responses to high-frequency sound in a freshwater crayfish, Cherax quadricarinatus
2023
Anthropogenic noise is recognised as an important environmental stressor that can have longterm negative consequences on species. In recent years, there has been increasing attention to the potential negative impact of noise pollution on species, with great concern for the importance of impacts on aquatic animal life. This study examined the effects of acoustic stress on the biochemical parameters of the freshwater crayfish Cherax quadricarinatus. The experiment was conducted in a tank equipped with an audio and video recording system using ten groups (five control and five test) of three adult crayfish (30 animals in total). The animals in the test group were exposed to acoustic signals [a…
Qanat, gebbie and water sources: the last refuge for the malacologican freshwater fauna in Palermo (Sicily, Italy)
2017
The surroundings of Palermo were characterized, over the centuries, by the presence of many natural environments of great ecological and faunal importance. These environments were placed in a context characterized by minimal and sustainable urban development and large agriculture areas, dedicated to the development of tree crops such as citrus and orchards. These crops were supported by an imposing irrigation system that, using natural resources such as watercourses, wells and springs, collected and distributed water in soils through tanks, gebbie, qanat, irrigation channels (saje), etc. Fresh water mollusks, like many other animal and vegetable organisms, spread from the natural freshwater…
Long-lasting effect of stress on susceptibility of a freshwater clam to copepod parasitism.
2005
The question whether a stress event can have a long-lasting effect on susceptibility to parasites was studied using a freshwater bivalve clam and its crustacean parasite as a model system. Anodonta piscinalis clams were collected from 2 populations during August–September 2002. Clams were transported to the laboratory and marked. The stressed clams were subjected to low oxygen for 25 days, while the unstressed control clams were caged in their lakes of origin for the same period. Then the clams were transported to a third lake where they were exposed to natural infections by the ergasilid copepod, Paraergasilus rylovi , 11 months after the stress event. The stressed clams were more intensiv…
The role of salmonid fishes in conservation of the endangered freshwater pearl mussel (Margaritifera margaritifera)
2016
The abundance of freshwater pearl mussels (Margaritifera margaritifera) has declined widely during the past century, and new conservation initiatives are needed. This thesis focused on the relationship between M. margaritifera and its salmonid host required for reproduction of this species. First, by exposing fish experimentally to glochidium larvae of M. margaritifera, different M. margaritifera populations were shown to demonstrate strong differences in their ability to parasitize different salmonid species. Atlantic salmon was clearly a better host for mussels in large river channels, whereas in small headwater tributaries brown trout was the best, or the only suitable, host. These findi…