Experimental reintroduction of the crayfish species Orconectes virilis into formerly acidified Lake 302S (Experimental Lakes Area, Canada)This paper is part of the series “Forty Years of Aquatic Research at the Experimental Lakes Area”.

2009 ◽  
Vol 66 (11) ◽  
pp. 1892-1902 ◽  
Author(s):  
Iain D. Phillips ◽  
Rolf D. Vinebrooke ◽  
Michael A. Turner
Keyword(s):  
Fish Predation ◽  
Boreal Lakes ◽  
Ecological Impacts ◽  
Total Biomass ◽  
Productive Capacity ◽  
Orconectes Virilis ◽  
Experimental Lakes Area ◽  
Important Species ◽  
Isotopic Analyses ◽  
Control Versus

Reintroduction of functionally important species is considered a key strategy for restoring damaged ecosystems. However, the sudden reappearance of an extirpated species may have adverse ecological impacts, degrading ecosystem services. Therefore, we experimentally reintroduced the crayfish Orconectes virilis into a biologically recovering, formerly acidified Boreal Shield lake (Lake 302S, Experimental Lakes Area, Canada) to determine its effect on the littoral food web following a 17-year absence. In June 2004, a single-factor experimental design consisting of two treatment levels (crayfish-less control versus 1.8 introduced crayfish·m–2) was replicated five times for a total of 10 littoral cages (4 m2). Orconectes virilis significantly (P < 0.05) suppressed the total biomass of other benthic invertebrates by 70% primarily because of declines in larval damselflies and midges. In addition, crayfish reduced periphytic biomass by 90% (P < 0.001). Stable isotopic analyses of the mesocosm food webs further indicated that O. virilis likely functioned as an omnivore, exerting direct and possibly indirect effects on other invertebrates and periphyton. Our findings highlight how the reintroduction of O. virilis must be balanced with adequate fish predation to prevent this species from becoming an invader and negatively affecting the productive capacity of boreal lakes.

Population Collapse of the Crayfish Orconectes virilis in Response to Experimental Whole-Lake Acidification

1989 ◽  
Vol 46 (6) ◽  
pp. 910-922 ◽  
Author(s):  
I. J. Davies
Keyword(s):  
Population Size ◽  
Population Decline ◽  
Fish Predation ◽  
Reference Population ◽  
Lake Acidification ◽  
Orconectes Virilis ◽  
Microsporidian Parasite ◽  
Experimental Lakes Area ◽  
Recruitment Failure ◽  
Northwestern Ontario

A population of Orconectes virilis in Lake 223 at the Experimental Lakes Area, northwestern Ontario, was monitored from 1976 to 1982 during an acidification experiment. O. virilis from nearby Lake 240 served as a reference population. Crayfish abundance remained stable as average epilimnion pH was gradually lowered from 6.49 (1976) to 5.93 (1978). In 1979 (pH 5.64) recruitment of young was poor and the overall population size [Formula: see text] fell from 105 800 to 60 300 animals. The decline continued in the complete absence of recruitment during 1980 (pH 5.59, [Formula: see text] and 1981 (pH 5.02, [Formula: see text]. Few crayfish survived until the spring of 1982. None were present from mid-summer 1982 to fall 1983 (average pH 5.09 to 5.13). Hatchling mortality and some egg loss appeared to have been the causes of recruitment failure. Acidification also produced a noticeable softening in the carapace of all intermoult crayfish. Growth, mortality, behaviour, and the basic reproductive functions of juvenile and adult crayfish did not change in response to acidification. Fish predation and the incidence of a microsporidian parasite apparently contributed little to the population decline.

scholarly journals Brook trout (Salvelinus fontinalis) extinction in small boreal lakes revealed by ephippia pigmentation: a preliminary analysis

2016 ◽  
Vol 7 (2) ◽  
Author(s):  
Alexandre Bérubé Tellier ◽  
Paul E. Drevnick ◽  
Andrea Bertolo
Keyword(s):  
Brook Trout ◽  
Fish Assemblages ◽  
Salvelinus Fontinalis ◽  
Sediment Cores ◽  
Experimental Studies ◽  
Cost Effective ◽  
Fish Predation ◽  
Boreal Lakes ◽  
Predation Pressure ◽  
Trout Population

<p>Ephippium pigmentation is a plastic trait which can be related to a trade-off between visual predation pressure and better protection of cladoceran eggs against different types of stress. Experimental studies showed that planktivorous fish exert a greater predation pressure on individuals carrying darker ephippia, but little is known about the variation of ephippium pigmentation along gradients of fish predation pressure in natural conditions. For this study, our experimental design included four small boreal lakes with known fish assemblages. Two of the lakes have viable brook trout (<em>Salvelinus fontinalis</em>) populations, whereas the other two lakes experienced brook trout extinctions during the 20<sup>th</sup> century. Cladoceran ephippia were extracted from sediment cores at layers corresponding to the documented post- extinction phase (1990's) and from an older layer (1950's) for which the brook trout population status is not known precisely. Our first objective was to determine whether brook trout extinction has a direct effect on both ephippium pigmentation and size. Our second objective was to give a preliminary assessment of the status of brook trout populations in the 1950's by comparing the variation in ephippia traits measured from this layer to those measured in the 1990's, for which the extinction patterns are well known. Cost-effective image analysis was used to assess variation in pigmentation levels in ephippia. This approach provided a proxy for the amount of melanin invested in each ephippium analysed. Our study clearly shows that ephippium pigmentation may represent a better indicator of the presence of fish predators than ephippium size, a trait that showed a less clear pattern of variation between lakes with and without fish. For the 1990's period, ephippia from fishless lakes were darker and showed a slight tendency to be larger than ephippia from lakes with brook trout. However, no clear differences in either ephippium size or pigmentation were observed between the 1990's and 1950's layers within each lake. This suggests that brook trout extinction already occurred before the 1950’s, or that brook trout population abundance was already extremely low before and after the 1990’s. Our preliminary study shows that ephippium pigmentation can be used as a tool to quickly assess present and past predation levels on zooplankton when only sediment samples are available.</p>

scholarly journals Life History and Population Dynamics of Green Crabs (Carcinus maenas)

Fishes ◽  
2019 ◽  
Vol 5 (1) ◽  
pp. 4 ◽  
Author(s):  
Alan M. Young ◽  
James A. Elliott
Keyword(s):  
Population Dynamics ◽  
Life History ◽  
Larval Development ◽  
Habitat Preferences ◽  
Carcinus Maenas ◽  
Ecological Impacts ◽  
Ecosystem Dynamics ◽  
Shore Crab ◽  
Restrictive Temperature ◽  
Important Species

Carcinus maenas (the “shore crab” or “European green crab”) is a very proficient invader (considered to be one of the world’s 100 worst invaders by the IUCN) due to its phenotypic plasticity, wide temperature and salinity tolerance, and an extensive omnivorous diet. Native to Atlantic Europe, it has established two well-studied nonindigenous populations in the northwestern Atlantic and northeastern Pacific and less-studied populations in Australia, Argentina and South Africa. Green crabs are eurythermal and euryhaline as adults, but they are limited to temperate coastlines due to more restrictive temperature requirements for breeding and larval development. They cannot tolerate wave-swept open shores so are found in wave-protected sheltered bays, estuaries and harbors. Carcinus maenas has been the subject of numerous papers, with over 1000 published in the past decade. This review provides an up-to-date account of the current published information on the life history and population dynamics of this very important species, including genetic differentiation, habitat preferences, physical parameter tolerances, reproduction and larval development, sizes of crabs, densities of populations, sex ratios, ecosystem dynamics and ecological impacts in the various established global populations of green crabs.

Abundance of demersal fish resources in the Persian Gulf and Oman Sea

2006 ◽  
Vol 86 (6) ◽  
pp. 1455-1462 ◽  
Author(s):  
T. Valinassab ◽  
R. Daryanabard ◽  
R. Dehghani ◽  
G.J. Pierce
Keyword(s):  
Persian Gulf ◽  
Central Area ◽  
Demersal Fish ◽  
Total Biomass ◽  
Trawl Survey ◽  
Important Species ◽  
Fish Resources ◽  
Oman Sea ◽  
Commercially Important ◽  
The Persian Gulf

We report on results of a trawl survey during 2003–2004 to assess the abundance of demersal fish resources in the Persian Gulf and Oman Sea. Samples were taken at a total of 316 trawl stations selected following a stratified random procedure. Catch rates (catch per unit area, CPUA) and total biomass were estimated. Total demersal fish biomass was estimated to be approximately 73,000 tonnes in Persian Gulf waters and approximately 39,000 tonnes in the Oman Sea. The lowest CPUA was recorded in the west of the study area (stratum A, approximately 1700 kg/n.m.2) and the highest in the east (stratum Q, 13943.4 kg/n.m.2), although density of commercially important species was higher in the central area (stratum K). Catch rate and biomass varied significantly in relation to seabed depth. Commercially important demersal species made up around 60% of the estimated total biomass. The most abundant species groups were rays, catfish, grunts, nemipterids and carangids. Several important species (e.g. silver pomfret, croakers and sharks) appear to have declined since the late 1970s while others, such as rays and catfish, have increased.

scholarly journals The taxonomic and functional biogeographies of phytoplankton and zooplankton communities across boreal lakes

2018 ◽  
Author(s):  
Nicolas F. St-Gelais ◽  
Richard J. Vogt ◽  
Paul A. del Giorgio ◽  
Beatrix E. Beisner
Keyword(s):  
Water Quality ◽  
Functional Traits ◽  
Trophic Interactions ◽  
Large Scale ◽  
Dispersal Limitation ◽  
Fish Predation ◽  
Functional Trait ◽  
Boreal Lakes ◽  
Environmental Drivers ◽  
Biogeographical Distribution

AbstractStrong trophic interactions link primary producers (phytoplankton) and consumers (zooplankton) in lakes. However, the influence of such interactions on the biogeographical distribution of the taxa and functional traits of planktonic organisms in lakes has never been explicitly tested. To better understand the spatial distribution of these two major aquatic groups, we related the distributions of their taxa and functional traits across boreal lakes (104 for zooplankton and 48 for phytoplankton) to a common suite of environmental and spatial factors. We directly tested the degree of coupling in their taxonomic and functional distributions across the subset of common lakes. Phytoplankton functional composition responded mainly to properties related to water quality, while zooplankton composition responded more strongly to lake morphometry. Overall, the spatial distributions of phytoplankton and zooplankton were coupled at taxonomic and functional levels but after controlling for the effect of environmental drivers (water quality and morphometry) and dispersal limitation, no residual coupling could be attributed to trophic interactions. The lack of support for the role of trophic interactions as a driver coupling the distribution of plankton communities across boreal lakes indicates that taxon-specific and functional trait driven ecological interactions may not modulate large-scale spatial patterns of phytoplankton and zooplankton in a coordinated way. Our results point to community structuring forces beyond the phytoplankton-zooplankton trophic coupling itself, and which are specific to each trophic level: fish predation for zooplankton and resources for phytoplankton.

scholarly journals Feeding habits variability of Lutjanus synagris and Lutjanus griseus in the littoral of Campeche, Mexico: an approach of food web trophic interactions between two snapper species

2020 ◽  
Vol 48 (4) ◽  
pp. 552-569 ◽  
Author(s):  
Paloma G. Juárez-Camargo ◽  
Atahualpa Sosa-López ◽  
Yassir Edén Torres-Rojas ◽  
Edgar Fernando Mendoza-Franco ◽  
Sergio Aguiñiga García
Keyword(s):  
Trophic Interactions ◽  
Feeding Habits ◽  
Relative Importance ◽  
Long Term Effects ◽  
Important Species ◽  
Δ13c And Δ15n ◽  
Spatial And Temporal Scales ◽  
Lutjanus Griseus ◽  
Coastal Marine ◽  
Isotopic Analyses

The study of the feeding habits variability (spatial and temporal scales) allows us to evaluate the trophic interactions between species, thus, the short and long-term effects of the removal of different species by the presence of different phenomena. In this study, we carried out stable isotope (δ13C and δ15N) and stomach content analyses to infer the trophic linkages between two snapper species (Lutjanus synagris and Lutjanus griseus) captured in the littoral of Campeche, Mexico. In total, 781 specimens were collected (528 L. synagris and 253 L. griseus) and based on relative importance index [%PSIRI] both snapper species consumed based on the prey-specific index of relative importance (PSIRI), Penaeidae family (PSIRI = 23.41%) was the most important species in the diet of Lutjanus synagris, while Callinectes sapidus (PSIRI = 21.45%) was the primary prey of Lutjanus griseus. The isotopic analyses indicated that both snapper species feed in the coastal-marine (δ15N: 10.6 to 12.1‰ and δ13C: -15.7 to -12.7‰); however, according to PERMANOVA, low diet similarity was found between snapper species (R = 0.07, P < 0.01), also, significant differences was detected in the δ15N and δ13C values between L. synagris, and L. griseus. Therefore, despite both snapper species presents similar trophic positions (L. synagris: 4.2 ± 0.2; L. griseus: 3.9 ± 0.1) and feeding behavior (according to SIBER = opportunistic predators), a low trophic overlap was observed, probably associated with the differential use of habitat in the coastal zone; where L. synagris is ecologically fed in areas of seagrass, while L. griseus is probably intermittent between pasture and mangrove areas, therefore, the role of each species is crucial in the dynamics of coastal-marine ecosystems as predators and potential structuring of the populations of their prey.

scholarly journals Changes in the functional features of macrophyte communities and driving factors across a 70-year period

Hydrobiologia ◽  
2020 ◽  
Vol 847 (18) ◽  
pp. 3811-3827 ◽  
Author(s):  
Marja Lindholm ◽  
Janne Alahuhta ◽  
Jani Heino ◽  
Jan Hjort ◽  
Heikki Toivonen
Keyword(s):  
Aquatic Macrophyte ◽  
Human Impacts ◽  
Boreal Lakes ◽  
Environmental Drivers ◽  
Functional Composition ◽  
Important Species ◽  
Macrophyte Communities ◽  
Functional Richness ◽  
Functional Features ◽  
Time Periods

AbstractFunctional homogenisation occurs across many areas and organism groups, thereby seriously affecting biodiversity loss and ecosystem functioning. In this study, we examined how functional features of aquatic macrophytes have changed during a 70-year period at community and species levels in a boreal lake district. At the community level, we examined if aquatic macrophyte communities showed different spatial patterns in functional composition and functional richness in relation to main environmental drivers between the time periods. We also observed each species in functional space to assess if species with certain sets of traits have become more common or rare in the 70-year study period. We found changes in the relationship between functional community composition and the environment. The aquatic macrophyte communities showed different patterns in functional composition between the two time periods, and the main environmental drivers for these changes were partly different. Temporal changes in functional richness were only partially linked to concomitant changes in the environment, while stable factors were more important. Species’ functional traits were not associated with commonness or rarity patterns. Our findings revealed that functional homogenisation has not occurred across these boreal lakes, ranging from small oligotrophic forest lakes to larger lakes affected by human impacts.

PopulationDynamics of Green Crabs (Carcinus maenas) -- A Review

2018 ◽  
Author(s):  
Alan Young ◽  
James Elliott
Keyword(s):  
Larval Development ◽  
Habitat Preferences ◽  
Carcinus Maenas ◽  
Ecological Impacts ◽  
Ecosystem Dynamics ◽  
Shore Crab ◽  
Restrictive Temperature ◽  
Important Species ◽  
Northeastern Pacific ◽  
S 100

Carcinus maenas (the &ldquo;shore crab&rdquo; or &ldquo;European green crab&rdquo;) is a very proficient invader (considered to be one of the world&rsquo;s 100 worst invaders by the IUCN) due to its phenotypic plasticity, wide temperature and salinity tolerance, and an extensive omnivorous diet. Native to Atlantic Europe, it has established two well-studied nonindigenous populations in the northwestern Atlantic and northeastern Pacific and less-studied populations in Australia, Argentina and South Africa. Green crabs are eurythermal and euryhaline as adults, but they are limited to temperate coastlines due to more restrictive temperature requirements for breeding and larval development. They cannot tolerate wave-swept open shores so are found in wave-protected sheltered bays, estuaries and harbors. C. maenas has been the subject of numerous papers, with over 1000 published in the past decade. This literature review provides an up-to-date account of the current published information on the population dynamics of this very important species, including habitat preferences, physical parameter tolerances, reproduction and larval development, sizes of crabs, densities of populations, sex ratios, ecosystem dynamics and ecological impacts in the various established global populations of green crabs.

PopulationDynamics of Green Crabs (Carcinus maenas) -- A Review

2018 ◽  
Author(s):  
Alan M. Young ◽  
James A. Elliott
Keyword(s):  
Larval Development ◽  
Habitat Preferences ◽  
Carcinus Maenas ◽  
Ecological Impacts ◽  
Ecosystem Dynamics ◽  
Shore Crab ◽  
Restrictive Temperature ◽  
Important Species ◽  
Northeastern Pacific ◽  
S 100

Carcinus maenas (the &ldquo;shore crab&rdquo; or &ldquo;European green crab&rdquo;) is a very proficient invader (considered to be one of the world&rsquo;s 100 worst invaders by the IUCN) due to its phenotypic plasticity, wide temperature and salinity tolerance, and an extensive omnivorous diet. Native to Atlantic Europe, it has established two well-studied nonindigenous populations in the northwestern Atlantic and northeastern Pacific and less-studied populations in Australia, Argentina and South Africa. Green crabs are eurythermal and euryhaline as adults, but they are limited to temperate coastlines due to more restrictive temperature requirements for breeding and larval development. They cannot tolerate wave-swept open shores so are found in wave-protected sheltered bays, estuaries and harbors. C. maenas has been the subject of numerous papers, with over 1000 published in the past decade. This literature review provides an up-to-date account of the current published information on the population dynamics of this very important species, including habitat preferences, physical parameter tolerances, reproduction and larval development, sizes of crabs, densities of populations, sex ratios, ecosystem dynamics and ecological impacts in the various established global populations of green crabs.

Rapid Communication / Communication RapideAmbient solar ultraviolet radiation and its effects on phosphorus flux into boreal lake phytoplankton communities

2002 ◽  
Vol 59 (7) ◽  
pp. 1090-1095 ◽  
Author(s):  
Paul C Frost ◽  
Marguerite A Xenopoulos
Keyword(s):  
Ultraviolet Radiation ◽  
P Uptake ◽  
Boreal Lakes ◽  
Particulate Phosphorus ◽  
Experimental Lakes Area ◽  
Solar Ultraviolet Radiation ◽  
Variable Effect ◽  
Phytoplankton Communities ◽  
P Flux ◽  
P Addition

We examined the effects of ultraviolet radiation (UVR) on net phosphorus (P) flux into phytoplankton communities in two boreal lakes at the Experimental Lakes Area (ELA), Canada. We manipulated P available to and irradiance received by phytoplankton during four different three-day incubations of dilution bioassays. Net P flux was estimated by measuring the accumulation of particulate P (that retained on glass fiber filters) over the incubation period. No effects of UVR on net P flux were found at ambient P levels in any of the experiments. At the highest levels of P addition, less particulate phosphorus (PP) accumulated in both the minus-UVB (~15–40%; photosynthetically active radiation (PAR) + UVA) and full-sunlight (~25–45%; PAR + UVA + UVB) exposed phytoplankton compared with those that received PAR only. Neither chlorophyll- nor carbon-specific net P flux was affected by UVR exposure at ambient P levels. However, at the highest levels of P enrichment, chlorophyll-specific net P flux increased in response to UVR in both lakes, whereas carbon-specific net P flux declined in one of the lakes and was unaffected by UV exposure in the second lake. Our results indicate that UVR can affect total PP accumulation in enriched systems, but not at ambient P levels, and that UVR has a weak and variable effect on biomass-specific P uptake in phytoplankton under enriched conditions.

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