scholarly journals Size-structured risk assessments govern Daphnia migration

2008 ◽  
Vol 276 (1655) ◽  
pp. 331-336 ◽  
Author(s):  
Lars-Anders Hansson ◽  
Samuel Hylander
Keyword(s):  
Surface Waters ◽  
Depth Distribution ◽  
Risk Assessments ◽  
Competitive Release ◽  
Threat Level ◽  
Diel Variations ◽  
Depth Separation ◽  
Migratory Patterns ◽  
Animal Mass ◽  
Individual Size

Abstract One of the more fascinating phenomena in nature is animal mass migrations and in oceans and freshwaters, diel variations in depth distribution of zooplankton are a phenomenon that has intrigued scientists for more than a century. In our study, we show that zooplankton are able to assess the threat level of ultraviolet radiation and adjust their depth distribution to this level at a very fine tuned scale. Moreover, predation risk induces a size-structured depth separation, such that small individuals, which we show are less vulnerable to predation than larger, make a risk assessment and continue feeding in surface waters during day, offering a competitive release from down-migrating larger animals. Hence, we mechanistically show that such simple organisms as invertebrate zooplankton are able to make individual, size-specific decisions regarding how to compromise between threats from both predators and UV radiation, and adjust their diel migratory patterns accordingly.

Human health risk assessments for three neuropharmaceutical compounds in surface waters

2008 ◽  
Vol 50 (3) ◽  
pp. 420-427 ◽  
Author(s):  
Joel P. Bercu ◽  
Neil J. Parke ◽  
Janice M. Fiori ◽  
Roger D. Meyerhoff
Keyword(s):  
Health Risk ◽  
Human Health ◽  
Surface Waters ◽  
Human Health Risk ◽  
Risk Assessments ◽  
Health Risk Assessments

scholarly journals Siphonophores from surface waters of the Colombian Pacific Ocean

2018 ◽  
Vol 99 (1) ◽  
pp. 67-80 ◽  
Author(s):  
Julian Uribe-Palomino ◽  
Raúl López ◽  
Mark J. Gibbons ◽  
Felipe Gusmão ◽  
Anthony J. Richardson
Keyword(s):  
Pacific Ocean ◽  
Surface Waters ◽  
Depth Distribution ◽  
Fish Larvae ◽  
Salinity Gradient ◽  
Abundant Species ◽  
Salinity Range ◽  
Fish Eggs ◽  
Positive Correlations ◽  
Colombian Pacific

Siphonophores are colonial hydrozoans that feed on zooplankton including fish larvae, and occur throughout the world's oceans from surface waters to ocean depths. Here we describe the composition of hyponeustonic siphonophores (0–3 m depth) from the tropical Colombian Pacific Ocean based on 131 plankton samples collected between June–October from 2001–2004. Samples were dominated by species of Calycophorae, with only three species of Physonectae identified, consistent with their deeper depth distribution. Muggiaea atlantica, Chelophyes contorta, Diphyes dispar, and Eudoxoides mitra were the most common of the 21 species identified. We found moderate structuring of the siphonophore community by the salinity gradient from inshore to offshore, and greater richness during the night because of diel vertical migration. Temperature did not play a significant role in structuring siphonophore communities, perhaps because of the narrow temperature range observed (3.5 °C). We extend the known temperature and salinity range of several species, including M. atlantica up to temperatures of 28.6 °C and salinities down to 24.7. Interestingly, only polygastric stages of M. atlantica were found, suggesting the reproductive stage of M. atlantica in tropical waters might be found in deeper waters. Chelophyes appendiculata was rare in our study and C. contorta was common, providing evidence they have a potential allopatric relationship, with C. contorta replacing C. appendiculata in warm water. Finally, we found siphonophore abundance was positively related to the abundance of copepods and fish eggs, with the top 13 most abundant species all having positive correlations, suggesting siphonophore abundances are tightly controlled by their food.

scholarly journals Early development of eye and retina in lanternfish larvae

2007 ◽  
Vol 24 (3) ◽  
pp. 423-436 ◽  
Author(s):  
A. BOZZANO ◽  
P.M. PANKHURST ◽  
A. SABATÉS
Keyword(s):  
Visual Field ◽  
Surface Waters ◽  
Depth Distribution ◽  
Gradual Increase ◽  
Adult Life ◽  
Morphological Characteristics ◽  
Rod Photoreceptors ◽  
Scotopic Sensitivity ◽  
Concurrent Development ◽  
Binocular Visual Field

The morphological characteristics of the eyes and the retinae of lanternfish larvae ofLampanyctus crocodilus,Benthosema glaciale, andMyctophum punctatumwere analyzed in pre-flexion, flexion, and post-flexion stages. Pre-flexion larvae ofL. crocodilus, the species with the shallowest depth distribution, had spherical eyes located antero-laterally on a strongly laterally-compressed head, suggesting a forward binocular visual field.B. glacialeandM. punctatumlarvae live deeper in the water column and had eyes elongated in the dorsal-ventral plane. The eyes ofB. glacialewere prominent, projecting slightly outward from a laterally-compressed head, suggesting a strongly laterally-directed visual field.M. punctaumhad stalked elongated eyes projecting from a dorso-ventrally flattened head. The eyes can be freely rotated allowing lateral, anterior and dorsally-directed vision. A prominent choroidal gland was situated beneath the ventral portion of the eye inM. punctatumandB. glaciale, while a smaller gland was present in the dorsal and ventral portions of the eye ofL. crocodilus. In pre-flexion stage larvae, the retina of all three species was differentiated with numerous rod photoreceptors in the peripheral retinal areas and fewer cone photoreceptors mainly distributed in the central retina. This distribution suggests concomitant enhancement of scotopic sensitivity in the vertical visual plane and improved photopic acuity in the lateral and forward visual directions. The concurrent development of cones and rods, as observed in the pre-flexion stage of myctophid larvae, is consistent with meeting the special demands of visual planktivory in sub-surface waters. During larval development a gradual increase of ROS length was also accompanied by a progressive loss of cones that were almost totally absent in post-flexion larvae. This can be interpreted as an adaptive response to an impending deep mesopelagic adult life.

Diel variations of the DMSP-to-chlorophyll a ratio in Northwestern Mediterranean surface waters

2000 ◽  
Vol 25 (2) ◽  
pp. 119-128 ◽  
Author(s):  
S Belviso ◽  
U Christaki ◽  
F Vidussi ◽  
J.-C Marty ◽  
M Vila ◽  
...  
Keyword(s):  
Chlorophyll A ◽  
Surface Waters ◽  
Diel Variations ◽  
Northwestern Mediterranean

Depth Distribution of Oceanic Shrimps (Decapoda; Natantia) off Oregon

1966 ◽  
Vol 23 (8) ◽  
pp. 1135-1143 ◽  
Author(s):  
William G. Pearcy ◽  
Carl A. Forss
Keyword(s):  
Surface Waters ◽  
Depth Distribution ◽  
Abundant Species ◽  
Near Surface ◽  
Northeast Pacific ◽  
Diel Vertical Migrations

Sixteen species of oceanic shrimps, seven Penaeidea and nine Caridea, appeared in 244 collections made within the upper 1500 m at one station in the northeast Pacific off Oregon. Most of the species were primarily mesopelagic in distribution.The most abundant species, Sergestes similis, was the only shrimp common in epipelagic waters at night and the only species clearly demonstrating diel vertical migrations. Night catches exceeded day catches in near-surface waters, while day catches exceeded night catches at mid-depths. Sergestes similis migrated into the upper 50 m at night and on one occasion was collected at the surface.

Assessing the risk from emerging infections

2009 ◽  
Vol 137 (11) ◽  
pp. 1521-1530 ◽  
Author(s):  
D. MORGAN ◽  
H. KIRKBRIDE ◽  
K. HEWITT ◽  
B. SAID ◽  
A. L. WALSH
Keyword(s):  
Systematic Approach ◽  
Animal Health ◽  
Good Evidence ◽  
Risk Assessments ◽  
Qualitative Assessment ◽  
Emerging Infections ◽  
Horizon Scanning ◽  
Threat Level ◽  
Potential Impact ◽  
The Uk

SUMMARYEmerging infections pose a constant threat to society and can require a substantial response, thus systems to assess the threat level and inform prioritization of resources are essential. A systematic approach to assessing the risk from emerging infections to public health in the UK has been developed. This qualitative assessment of risk is performed using algorithms to consider the probability of an infection entering the UK population, and its potential impact, and to identify knowledge gaps. The risk assessments are carried out by a multidisciplinary, cross-governmental group of experts working in human and animal health. This approach has been piloted on a range of infectious threats identified by horizon scanning activities. A formal risk assessment of this nature should be considered for any new or emerging infection in humans or animals, unless there is good evidence that the infection is neither a recognized human disease nor a potential zoonosis.

Increased abundance and depth distribution of pelagic crustacean zooplankton during hypolimnetic oxygenation in a deep, eutrophic Alberta lake

1997 ◽  
Vol 54 (9) ◽  
pp. 2146-2156 ◽  
Author(s):  
K M Field ◽  
E E Prepas
Keyword(s):  
Dissolved Oxygen ◽  
Surface Waters ◽  
Depth Distribution ◽  
Daphnia Pulex ◽  
Crustacean Zooplankton ◽  
Bosmina Longirostris ◽  
South Basin ◽  
The North ◽  
Hypolimnetic Oxygenation ◽  
Species Specific

Since June 1988, the north basin of eutrophic Amisk Lake has been treated by hypolimnetic oxygenation, while the south basin has served as a reference. In summer 1989, hypolimnetic dissolved oxygen (DO) concentrations were >=>1 mg ·L-1 in the treatment basin, while they fell to <1 mg ·L-1 in the reference basin by early July. There were no apparent treatment effects on biomass, abundance, or distribution of zooplankton in surface waters (0-10 m). However, in summer 1989, hypolimnetic abundances of two of four species (Daphnia longiremis and Daphnia pulex) were greater in the treatment than in the reference basin (P < 0.03) and than in the north basin in summer 1984 (4 years pretreatment). In the hypolimnion, D. longiremis, D. pulex, Bosmina longirostris, and Diacyclops bicuspidatus thomasi were found at greater median depths (P < 0.001) in the treatment than in the reference basin. Median depths of these four species in the hypolimnion tracked species-specific DO concentrations of between 1.5 and 2.3 mg ·L-1. Coincident with enhanced DO concentrations in the treatment basin in August, D. longiremis migrated vertically in the treatment basin (median depth day versus night, P < 0.001, median migration 4 m), but not in the reference basin (P > 0.9).

scholarly journals Modeling Regulatory Threshold Levels for Pesticides in Surface Waters from Effect Databases

Data ◽  
2019 ◽  
Vol 4 (4) ◽  
pp. 150
Author(s):  
Lara Petschick ◽  
Sascha Bub ◽  
Jakob Wolfram ◽  
Sebastian Stehle ◽  
Ralf Schulz
Keyword(s):  
Surface Waters ◽  
Aquatic Organisms ◽  
Risk Assessments ◽  
Threshold Levels ◽  
Exposure Data ◽  
Baseline Information ◽  
Us Epa ◽  
Validity Criteria ◽  
Ecotoxicological Effect

Regulatory threshold levels (RTL) represent robust benchmarks for assessing risks of pesticides, e.g., in surface waters. However, comprehensive scientific risk evaluations comparing RTL to measured environmental concentrations (MEC) of pesticides in surface waters were yet restricted to a low number of pesticides, as RTL are only available after extensive review of regulatory documents. Thus, the aim of the present study was to model RTL equivalents (RTLe) for aquatic organisms from publicly accessible ecotoxicological effect databases. We developed a model that applies validity criteria in accordance with official US EPA review guidelines and validated the model against a set of manually retrieved RTL (n = 49). Model application yielded 1283 RTLe (n = 676 for pesticides, plus 607 additional RTLe for other use types). In a case study, the usability of RTLe was demonstrated for a set of 27 insecticides by comparing RTLe and RTL exceedance rates for 3001 MEC from US surface waters. The provided dataset enables thorough risk assessments of surface water exposure data for a comprehensive number of substances. Especially regions without established pesticide regulations may benefit from this dataset by using it as a baseline information for pesticide risk assessment and for the identification of priority substances or potential high-risk regions.

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