Sub-fossils of cladocerans in the surface sediment of 135 lakes as proxies for community structure of zooplankton, fish abundance and lake temperature

Hydrobiologia ◽  
2003 ◽  
Vol 491 (1-3) ◽  
pp. 321-330 ◽  
Author(s):  
Erik Jeppesen ◽  
Jens Peder Jensen ◽  
Torben L. Lauridsen ◽  
Susanne L. Amsinck ◽  
Kirsten Christoffersen ◽  
...  
Keyword(s):  
Community Structure ◽  
Surface Sediment ◽  
Fish Abundance ◽  
Lake Temperature

scholarly journals Fish community structure of Juramento reservoir, São Francisco River basin, Minas Gerais, Brazil

2006 ◽  
Vol 23 (3) ◽  
pp. 832-840 ◽  
Author(s):  
André R. M. Silva ◽  
Gilmar B. Santos ◽  
Thiago Ratton
Keyword(s):  
Community Structure ◽  
Native Species ◽  
Fish Community ◽  
Fish Fauna ◽  
Fish Abundance ◽  
Fish Community Structure ◽  
Migratory Species ◽  
Wet Season ◽  
Dry Period ◽  
The Relationship

Many rivers in Brazil as the São Francisco (SFR) have been impounded for reservoirs construction purposes. However, there is a lack of knowledge on their fish fauna in many areas, including headwaters. The present study aimed to describe the fish community structure from Juramento reservoir, located on Juramento River, a branch of SFR basin. Six bimonthly samplings were made in four different sites. Gill and cast nets, beach seines and sieves were used to collect fish. Ecological indexes as well as the relationship between fish abundance and some limnological variables were determined. 3288 fish belonging to 33 species (16.5% of the total described for SFR basin) were captured, being 75.7% Characiformes, 18.1% Siluriformes, 3% Cyprinodontiformes and 3% Gymnotiformes. Only two non-native species, 'tamboatá' - Hoplosternum littorale (Hancock, 1828) and 'trairão' - Hoplias lacerdae Ribeiro, 1908 were found. The highest catches in number occurred in the dry period (March-October) and the lowest one in the wet season (November-February). Diversity was higher at Barragem station and richness did not vary between reservoir zones. Five migratory species were found downstream of the dam (four exclusively there), whereas only the 'curimbatá-pioa' - Prochilodus costatus Valenciennes, 1850 occurred in the reservoir. The low observed correlations between fish abundance and the limnological variables utilized suggest that the local fish fauna is not strongly affected by their variation.

Effects of the cleaner fish Labroides dimidiatus on grazing fishes and coral reef benthos

2020 ◽  
Vol 643 ◽  
pp. 99-114
Author(s):  
AS Grutter ◽  
S Bejarano ◽  
KL Cheney ◽  
AW Goldizen ◽  
T Sinclair-Taylor ◽  
...  
Keyword(s):  
Community Structure ◽  
Benthic Community ◽  
Foraging Behaviour ◽  
Fish Abundance ◽  
Fish Diversity ◽  
Benthic Community Structure ◽  
Group Foraging ◽  
Cleaner Fish ◽  
Labroides Dimidiatus ◽  
Positive Effect

Territorial and roving grazing fishes farm, and feed on, algae, sediment, or detritus, thus exerting different influences on benthic community structure, and are common clients of cleaner fish. Whether cleaners affect grazing-fish diversity and abundance, and indirectly the benthos, was tested using reefs maintained free of the bluestreak cleaner wrasse Labroides dimidiatus for 8.5 yr (removals) compared with controls. We quantified fish abundance per grazing functional group, foraging rates of roving grazers, cleaning rates of roving grazers by L. dimidiatus, reef benthos composition, and fouling material on settlement tiles. Abundances of ‘intensive’ and ‘extensive’ territorial farmers, non-farmers, parrotfishes and Acanthurus spp. were lower on removal than control reefs, but this was not the case for ‘indeterminate’ farmers and Ctenochaetus striatus. Foraging rates of Acanthurus spp. and C. striatus were unaffected by cleaner presence or cleaning duration. This suggests some robustness of the grazers’ foraging behaviour to loss of cleaners. Acanthurus spp. foraged predominantly on sediment and detritus, whereas C. striatus and parrotfishes grazed over algal turfs. Nevertheless, benthic community structure and amount of organic and inorganic material that accumulated over 3.5 mo on tiles were not affected by cleaner presence. Thus, despite greater abundances of many roving grazers, and consequently higher grazing rates being linked to the presence of cleaners, the benthos was not detectably affected by cleaners. This reveals that the positive effect of cleaners on fish abundance is not associated with a subsequent change in the benthos as predicted. Rather, it suggests a resilience of benthic community structure to cleaner-fish loss, possibly related to multiple antagonistic effects of different grazer functional groups. However, losing cleaners remains a problem for reefs, as the lack of cleaning has adverse consequences for fish physiology and populations.

scholarly journals Depth Distribution and Assembly of Sulfate-Reducing Microbial Communities in Marine Sediments of Aarhus Bay

2017 ◽  
Vol 83 (23) ◽  
Author(s):  
Lara M. Jochum ◽  
Xihan Chen ◽  
Mark A. Lever ◽  
Alexander Loy ◽  
Bo Barker Jørgensen ◽  
...  
Keyword(s):  
Community Structure ◽  
Community Composition ◽  
Marine Sediments ◽  
Surface Sediment ◽  
Depth Distribution ◽  
Coastal Sediments ◽  
Small Subset ◽  
Main Site ◽  
Sulfate Reducing ◽  
Fresh Organic Matter

ABSTRACT Most sulfate-reducing microorganisms (SRMs) present in subsurface marine sediments belong to uncultured groups only distantly related to known SRMs, and it remains unclear how changing geochemical zones and sediment depth influence their community structure. We mapped the community composition and abundance of SRMs by amplicon sequencing and quantifying the dsrB gene, which encodes dissimilatory sulfite reductase subunit beta, in sediment samples covering different vertical geochemical zones ranging from the surface sediment to the deep sulfate-depleted subsurface at four locations in Aarhus Bay, Denmark. SRMs were present in all geochemical zones, including sulfate-depleted methanogenic sediment. The biggest shift in SRM community composition and abundance occurred across the transition from bioturbated surface sediments to nonbioturbated sediments below, where redox fluctuations and the input of fresh organic matter due to macrofaunal activity are absent. SRM abundance correlated with sulfate reduction rates determined for the same sediments. Sulfate availability showed a weaker correlation with SRM abundances and no significant correlation with the composition of the SRM community. The overall SRM species diversity decreased with depth, yet we identified a subset of highly abundant community members that persists across all vertical geochemical zones of all stations. We conclude that subsurface SRM communities assemble by the persistence of members of the surface community and that the transition from the bioturbated surface sediment to the unmixed sediment below is a main site of assembly of the subsurface SRM community. IMPORTANCE Sulfate-reducing microorganisms (SRMs) are key players in the marine carbon and sulfur cycles, especially in coastal sediments, yet little is understood about the environmental factors controlling their depth distribution. Our results suggest that macrofaunal activity is a key driver of SRM abundance and community structure in marine sediments and that a small subset of SRM species of high relative abundance in the subsurface SRM community persists from the sulfate-rich surface sediment to sulfate-depleted methanogenic subsurface sediment. More generally, we conclude that SRM communities inhabiting the subsurface seabed assemble by the selective survival of members of the surface community.

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