scholarly journals A typology for fish-based assessment of the ecological status of lowland lakes with description of the reference fish communities

Limnologica ◽  
2014 ◽  
Vol 49 ◽  
pp. 18-25 ◽  
Author(s):  
David Ritterbusch ◽  
Uwe Brämick ◽  
Thomas Mehner
2021 ◽  
Vol 27 (3) ◽  
pp. 48-67
Author(s):  
M. O’Reilly ◽  
J. Boyle ◽  
S. Nowacki ◽  
M. Elliott ◽  
R. Foster

The history of monitoring transitional water fish in Scotland is briefly outlined. The requirements of the EU Water Framework Directive are explained and how this applies to the monitoring of transitional water fish communities in Scotland is described. The development of a monitoring programme for Scotland is outlined, including sampling methods and strategies. Six transitional waters were selected as representative for Scotland covering three different types of transitional water. A multi-metric tool, the Transitional Water Fish Classification Index was used to assess the ecological status of the fish communities in these waters and the operation of the different metrics and the creation of appropriate reference conditions is explained. The assessment tool was applied to survey data from 2005 to 2018, although only the more recent data fully met the tool requirements. The species composition and abundances in the respective transitional waters were compared. The fully valid surveys were all classed as of Good or High status, indicating the fish communities in all the representative transitional waters appeared to be in good ecological health. The efficacy of the different metrics is considered and some issues with Metric 2, enumerating migratory species, are discussed at length. A new multi-metric tool, the Estuarine Multi-metric Fish Index, is briefly discussed and its introduction for the assessments in Scotland is recommended.


2021 ◽  
Author(s):  
D Bănăduc ◽  
Michael Joy ◽  
H Olosutean ◽  
S Afanasyev ◽  
A Curtean-Bănăduc

© 2020, The Author(s). Background: Climate changes influence the ecosystems and induce potential risks regarding the natural products and services; the human society should predict and adapt in time to these coming global challenges. This research highlights a possible fragmentation of some of the Lower Danube River Basin lentic ecosystems fish populations in a climate change scenario. Results: The studied climate change potential events will affect 18 fish species of economic interest and eight of conservation interest and will induce disorder in some of the Lower Danube specific type of fish communities. The studied area was identified as a significant hot spot regarding the fish fauna ecological status major hazard, in a possible climate change (heating–drought–water depth decreasing) sequence of potential future events. Primarily the southern lakes of the studied area can be negatively influenced by the decreasing of the lakes water quality and quantity, some of the spawning habitats will vanish, some habitats and species will disappear, suspended sediment and nutrient levels in water will increase, eutrophication phenomenon will increase, the hydrological connectivity will diminish, fish associations’ structure will significantly change, etc. Conclusions: The climate changes trend in the Lower Danube Basin will affect the studied lakes ecological state and associated fish communities; mitigating measures are urgently needed. The future potential relative isolation of researched lakes by the surrounding hydrographical nets, for safety reasons of human communities or to convert inland areas should be banned specially for the lakes: Balta Domnească, Razelm, Tăbăcărie, Siutghiol, Taşaul, Tatlageac, Sinoe, Potcoava, Snagov, Comana, Victoria Gheormane, Dunărea Veche, Oltina, and Bugeac. Some of the researched lakes should be managed as wetlands of international importance and as important stepping stone areas for the fish fauna of the Danube Basin: Snagov, Comana, Victoria Gheormane, Dunărea Veche, Oltina, and Bugeac.


2021 ◽  
Vol 4 ◽  
Author(s):  
Sinziana Rivera ◽  
Valentin Vasselon ◽  
Frederic Rimet ◽  
Agnès Bouchez

Diatoms, macroinvertebrates and fish communities are widely used for the assessment of the ecological status of rivers and lakes. Metabarcoding studies of these communities are usually performed from “bulk” samples in the case of diatoms and macroinvertebrates; and from water samples in the case of fish. Recent studies, suggest that aquatic biofilms can physically act as environmental catchers of environmental DNA (eDNA) (e.g. Mariani et al. 2019). Thus, we propose an alternative metabarcoding approach to study macroinvertebrates and fishes directly from this matrix. The capacity of aquatic biofilms to catch macroinvertebrate eDNA was tested from a previous study in Mayotte Island were both biofilm samples and macroinvertebrate morphological inventories were available at same river sites (Rivera et al. 2021). First, macroinvertebrate specimens were identified based on their morphological characteristics. Second, DNA was extracted from biofilms, and macroinvertebrate communities were targeted using a standard COI barcode. The resulting morphological and molecular inventories were compared. Our results showed that both methods provided comparable structures and diversities for macroinvertebrate communities when using unassigned OTUs suggesting that macroinvertebrate DNA is present in biofilms and representative of the communities. However, after taxonomic assignment of OTUs, diversity and richness were no longer correlated. Indeed, many constraints were observed as the need for: a) more specific primers to avoid co-amplification of untargeted taxa inhabiting biofilms, b) primers targeting shorter barcodes to sequence more easily degraded eDNA that may be captured in biofilms, and c) a reference database well adapted to our tropical study sites. Finally, even if the results of this first study were encouraging, we wanted to test the biofilm approach on organisms that do not inhabit this environmental matrix in order to be able to distinguish between intra or extra-cellular DNA. Based on these observations, a second study looking for a fish eDNA signal in aquatic biofilms was performed. Environmental biofilm and water samples were collected in parallel at littoral sites at Lake Geneva. DNA was extracted from these samples, and fish communities were targeted using a standard 12S barcode. The molecular inventories derived from the biofilm and the water samples were compared. Both methods provide comparable floristic lists, providing a novel approach for ecological studies related to fish phenology using eDNA in biofilms. Our results open the door to the study of diatoms, macroinvertebrates and fish communities through metabarcoding from a single matrix reducing sampling efforts and costs.


Water ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 3522
Author(s):  
Vanna Nuon ◽  
Sovan Lek ◽  
Peng Bun Ngor ◽  
Nam So ◽  
Gaël Grenouillet

The Mekong River is one of the world’s largest rivers and has an annual captured fish production of about 2.3 million tonnes, equivalent to around 11 billion USD. Although the Mekong provides important ecological and socioeconomic benefits to millions of people, it is facing intensive change due to anthropogenic stressors. Therefore, it is necessary to understand the changes to the spatiotemporal fish communities to inform sustainable fisheries management. Here, we aimed to characterize patterns of the fish communities and identify the ecological status of each fish community using daily catch data from 2007 to 2018 at 25 monitoring sites in the Lower Mekong Basin (LMB). The collected data were classified by a self-organizing map into four main groups. Group 4 represented the lower Vietnam Mekong Delta (VMD), while groups 1, 2, and 3 were subdivided into subgroups 1a (upper LMB), 1b (upper and middle LMB), 2a (Mekong River below the Khone Falls and Sesan River), 2b (Mekong River below the Khone Falls and Sekong, Sesan and Srepok (3S) Rivers), 3a (Floodplain-Tonle Sap and Songkhram) and 3b (upper VMD). Among the 571 species recorded, 119 were identified as indicator species. Based on the abundance and biomass comparison curves, the fish community of 2b was in a healthier condition with a positive W-statistic value while the rest had a negative W-statistic value. The highest species richness and diversity were observed in 3a and 2b, so these subgroups deserve high management and conservation priority. Likewise, 1a should also be considered as a high priority area since it harbors several endangered and long-distant migratory fishes. It was also noticed that the fish communities of groups 3 and 4, located far from the hydropower dams, remained mostly unchanged compared to those of groups 1 and 2, close to the mainstream and tributary dams in the upper LMB and 3S Rivers.


2020 ◽  
Author(s):  
D Bănăduc ◽  
Michael Joy ◽  
H Olosutean ◽  
S Afanasyev ◽  
A Curtean-Bănăduc

© 2020, The Author(s). Background: Climate changes influence the ecosystems and induce potential risks regarding the natural products and services; the human society should predict and adapt in time to these coming global challenges. This research highlights a possible fragmentation of some of the Lower Danube River Basin lentic ecosystems fish populations in a climate change scenario. Results: The studied climate change potential events will affect 18 fish species of economic interest and eight of conservation interest and will induce disorder in some of the Lower Danube specific type of fish communities. The studied area was identified as a significant hot spot regarding the fish fauna ecological status major hazard, in a possible climate change (heating–drought–water depth decreasing) sequence of potential future events. Primarily the southern lakes of the studied area can be negatively influenced by the decreasing of the lakes water quality and quantity, some of the spawning habitats will vanish, some habitats and species will disappear, suspended sediment and nutrient levels in water will increase, eutrophication phenomenon will increase, the hydrological connectivity will diminish, fish associations’ structure will significantly change, etc. Conclusions: The climate changes trend in the Lower Danube Basin will affect the studied lakes ecological state and associated fish communities; mitigating measures are urgently needed. The future potential relative isolation of researched lakes by the surrounding hydrographical nets, for safety reasons of human communities or to convert inland areas should be banned specially for the lakes: Balta Domnească, Razelm, Tăbăcărie, Siutghiol, Taşaul, Tatlageac, Sinoe, Potcoava, Snagov, Comana, Victoria Gheormane, Dunărea Veche, Oltina, and Bugeac. Some of the researched lakes should be managed as wetlands of international importance and as important stepping stone areas for the fish fauna of the Danube Basin: Snagov, Comana, Victoria Gheormane, Dunărea Veche, Oltina, and Bugeac.


2020 ◽  
Author(s):  
D Bănăduc ◽  
Michael Joy ◽  
H Olosutean ◽  
S Afanasyev ◽  
A Curtean-Bănăduc

© 2020, The Author(s). Background: Climate changes influence the ecosystems and induce potential risks regarding the natural products and services; the human society should predict and adapt in time to these coming global challenges. This research highlights a possible fragmentation of some of the Lower Danube River Basin lentic ecosystems fish populations in a climate change scenario. Results: The studied climate change potential events will affect 18 fish species of economic interest and eight of conservation interest and will induce disorder in some of the Lower Danube specific type of fish communities. The studied area was identified as a significant hot spot regarding the fish fauna ecological status major hazard, in a possible climate change (heating–drought–water depth decreasing) sequence of potential future events. Primarily the southern lakes of the studied area can be negatively influenced by the decreasing of the lakes water quality and quantity, some of the spawning habitats will vanish, some habitats and species will disappear, suspended sediment and nutrient levels in water will increase, eutrophication phenomenon will increase, the hydrological connectivity will diminish, fish associations’ structure will significantly change, etc. Conclusions: The climate changes trend in the Lower Danube Basin will affect the studied lakes ecological state and associated fish communities; mitigating measures are urgently needed. The future potential relative isolation of researched lakes by the surrounding hydrographical nets, for safety reasons of human communities or to convert inland areas should be banned specially for the lakes: Balta Domnească, Razelm, Tăbăcărie, Siutghiol, Taşaul, Tatlageac, Sinoe, Potcoava, Snagov, Comana, Victoria Gheormane, Dunărea Veche, Oltina, and Bugeac. Some of the researched lakes should be managed as wetlands of international importance and as important stepping stone areas for the fish fauna of the Danube Basin: Snagov, Comana, Victoria Gheormane, Dunărea Veche, Oltina, and Bugeac.


2021 ◽  
Author(s):  
D Bănăduc ◽  
Michael Joy ◽  
H Olosutean ◽  
S Afanasyev ◽  
A Curtean-Bănăduc

© 2020, The Author(s). Background: Climate changes influence the ecosystems and induce potential risks regarding the natural products and services; the human society should predict and adapt in time to these coming global challenges. This research highlights a possible fragmentation of some of the Lower Danube River Basin lentic ecosystems fish populations in a climate change scenario. Results: The studied climate change potential events will affect 18 fish species of economic interest and eight of conservation interest and will induce disorder in some of the Lower Danube specific type of fish communities. The studied area was identified as a significant hot spot regarding the fish fauna ecological status major hazard, in a possible climate change (heating–drought–water depth decreasing) sequence of potential future events. Primarily the southern lakes of the studied area can be negatively influenced by the decreasing of the lakes water quality and quantity, some of the spawning habitats will vanish, some habitats and species will disappear, suspended sediment and nutrient levels in water will increase, eutrophication phenomenon will increase, the hydrological connectivity will diminish, fish associations’ structure will significantly change, etc. Conclusions: The climate changes trend in the Lower Danube Basin will affect the studied lakes ecological state and associated fish communities; mitigating measures are urgently needed. The future potential relative isolation of researched lakes by the surrounding hydrographical nets, for safety reasons of human communities or to convert inland areas should be banned specially for the lakes: Balta Domnească, Razelm, Tăbăcărie, Siutghiol, Taşaul, Tatlageac, Sinoe, Potcoava, Snagov, Comana, Victoria Gheormane, Dunărea Veche, Oltina, and Bugeac. Some of the researched lakes should be managed as wetlands of international importance and as important stepping stone areas for the fish fauna of the Danube Basin: Snagov, Comana, Victoria Gheormane, Dunărea Veche, Oltina, and Bugeac.


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