The biology of harpacticoid copepods in the meiofauna of shallow subtidal sands

1986 ◽  
Vol 90 ◽  
pp. 303-316
Author(s):  
B. L. S. Hardy ◽  
P. R. O. Barnett
Keyword(s):  
Egg Production ◽  
Small Fish ◽  
Adult Males ◽  
Large Numbers ◽  
Harpacticoid Copepods ◽  
Main Period ◽  
Shallow Subtidal ◽  
Viable Sperm ◽  
Gravid Females ◽  
Distinct Period

SynopisAn account is given of the benthic harpacticoid copepods of a medium grade subtidal sand at a depth of 8–5 m (below chart datum) off the Ayrshire coast at Hunterston. It is the first account of seasonal changes in subtidal harpacticoids in the Firth of Clyde.Most of the population is restricted to the top 1 cm layer of sand and this is considered to be related to food availability. There were considerable variations in total densities with largest numbers occurring in late June, as seawater temperatures increased rapidly towards the summer maxima.Two species examined in detail, Asellopsis hispida and Harpacticus flexus each had one distinct period of reproduction during the year. Gravid females appeared first during the coldest months (January and February) followed by large numbers of copepodites from late April to June, culminating in large numbers of adults in June. Adult males clasped female stages only in May and June, after the main period of egg production. It is thought that viable sperm is carried by the adult females for about six to seven months, supposedly until the next period of egg production the following year. Adults of Harpacticus flexus are thought to be an important source of food for juvenile and small fish, particularly during July.

scholarly journals Contributions to the biology of the mackerel, Scomber scombrus L. III. Age and growth

1952 ◽  
Vol 30 (3) ◽  
pp. 549-569 ◽  
Author(s):  
G. A. Steven
Keyword(s):  
Sexual Maturity ◽  
Age Groups ◽  
Age And Growth ◽  
Small Fish ◽  
Massachusetts Bay ◽  
Scomber Scombrus ◽  
Bay Area ◽  
Large Numbers ◽  
The Common ◽  
Young Of The Year

The first serious attempt to determine the age and growth rate of the common mackerel (Scomber scombrus L.) appears to have been made by Captain Atwood in 1856 (quoted by Brown Goode, 1884, p. 116) in the Massachusetts Bay area of northern North America. Small fish caught by Atwood in October of that year measuring 6½–7 in. in length (16.5–17.5 cm.) he believed to be the young of the year (i.e. they belonged to the O-group). Mackerel belonging to this group he calls ‘spikes’. ‘Blinks', ‘tinkers’ and ‘second size’ fish he assigns to the I-, II- and III-year age groups respectively, but unfortunately gives no data as to the sizes of those categories, merely stating that everyone well acquainted with mackerel makes the same groupings ‘as there seems to be a line of demarkation between the different kinds which stands out prominently’. Sixteen years later, on 27 July 1872, Malm (1877, p. 409) observed large numbers of small mackerel close inshore in the Gullmarfjord near Christineberg. Several tons of those mackerel were enclosed in a seine, but only ten specimens were retained as all the others escaped through the meshes. These ten fish ranged in length from 67 to 100 mm. and Malm surmised their age to be 13 months. Collett (1880, p. 18) stated that on the coast of Norway I-year-old mackerel are ‘fingerlang’. To fish of 20 cm., taken at the end of August, he ascribed (without supporting data) an age of 2 years, with sexual maturity supervening at 3 years at an unspecified length.

An efficient method for collecting large samples of live copepods free from detritus

2010 ◽  
Vol 61 (5) ◽  
pp. 621 ◽  
Author(s):  
Carl J. Svensson ◽  
Glenn A. Hyndes ◽  
Paul S. Lavery
Keyword(s):  
Fatty Acids ◽  
Food Web ◽  
Trophic Levels ◽  
Aquatic Systems ◽  
New Method ◽  
Aquatic Environments ◽  
Web Studies ◽  
Large Samples ◽  
Large Numbers ◽  
Harpacticoid Copepods

Meiofauna are often important in the transfer of organic material to higher trophic levels in aquatic environments. However, in food web analysis the group is frequently pooled or ignored owing to the difficulty in isolating individual components of the assemblage. In this study, we developed and tested a new method for extracting photopositive and detritus-free copepod samples from sediments, and compared this method to a previous technique (Couch 1989). In our initial trials, ∼400 copepods (all orders included) were collected in 15 min compared with 60 copepods using Couch’s method. In subsequent trials that focussed on specific orders of copepods, our method was at least 10 times more efficient than Couch’s method at collecting cyclopoid and harpacticoid copepods from sediments. The new method requires very little supervision and there is no requirement for a particular intensity of light. This method can increase the collection of large numbers of photopositive copepods in aquatic systems, and thereby facilitate the inclusion of this important component into future food web studies, particularly those using biomarkers such as stable isotopes or fatty acids.

Population size and spatial ecology of Blanding’s Turtle (Emydoidea blandingii) in South March Highlands, Ottawa, Ontario, Canada

2015 ◽  
Vol 93 (7) ◽  
pp. 509-514 ◽  
Author(s):  
Caleb T. Hasler ◽  
Kevin Robinson ◽  
Nick Stow ◽  
Shawn R. Taylor
Keyword(s):  
Population Size ◽  
Spatial Ecology ◽  
Road Construction ◽  
Home Range Size ◽  
Adult Males ◽  
Emydoidea Blandingii ◽  
Blanding's Turtle ◽  
The Road ◽  
Gravid Females ◽  
Blanding’S Turtle

Between 2010 and 2011, an arterial road was constructed within provincially significant wetlands in the South March Highlands (SMH) located in Ottawa, Ontario, Canada. The wetlands and adjacent upland areas were determined to be sensitive habitat for Blanding’s Turtles (Emydoidea blandingii (Holbrook, 1838)) during the approval and permitting process, and a population study was required as part of the road construction project. The study consisted of a 4-year mark–recapture program and a movement study of radio-tagged adult turtles. General findings included the identification of 27 adult males and 55 females and a population estimate of 93 adults (95% Cl: 86–118). A 1:2.32 male to female sex bias was also found. Mean home-range size was 19.06 ha and tagged turtles moved, on average, more per observation in 2013 (191.40 m compared with 89.75 and 123.04 m in 2011 and 2012, respectively). Previously reported differences in movement patterns between males, females, and gravid females were not observed. The SMH Blanding’s Turtle population should be closely monitored because urban development continues in the area, which may further reduce the population size. Understanding the biology of imperiled populations across species’ ranges is necessary to promote conservation and adaptive wildlife management.

scholarly journals Scavenging behaviour by Ergalatax contractus (Gastropoda: Muricidae) and interactions with Nassarius nodifer (Gastropoda: Nassariidae) in the Cape d'Aguilar Marine Reserve, Hong Kong

2006 ◽  
Vol 86 (1) ◽  
pp. 141-152 ◽  
Author(s):  
Brian Morton
Keyword(s):  
Hong Kong ◽  
Field Experiments ◽  
Marine Reserve ◽  
Flowing Water ◽  
Large Numbers ◽  
Baited Traps ◽  
Behavioural Characteristics ◽  
Shallow Subtidal ◽  
The Mean ◽  
Mean Time

Aspects of the feeding behaviour of Ergalatax contractus (Muricidae) were studied. Field experiments demonstrated that large numbers of individuals of this species, comprising ∼90% of a suite of gastropod scavengers, were attracted to baited traps in the subtidal sands of Lobster Bay, Cape d'Aguilar Marine Reserve, Hong Kong. Laboratory experiments identified the effective chemo-detection distances of E. contractus as 60 cm in still and >80 cm in flowing water, respectively. The average times to arrival at bait in still and flowing water were 92.3 and 69.0 min, respectively, but were significantly less for individuals experiencing a longer period of starvation. The mean time taken for E. contractus to consume a meal was 70.6 min.Comparisons were made between Ergalatax contractus and Nassarius nodifer, representative of a suite of sympatric scavenging nassariids in Lobster Bay. The nassariid arrived significantly faster at bait in both still (30.2 min) and flowing water (20.8 min) than E. contractus and fed faster (25.7 min), as is typical of representatives of the Nassariidae. Although the two species partition carrion resources temporally, manipulation experiments provided evidence for inter-specific competition between them. That is, although E. contractus possesses the morphological and behavioural characteristics of a predator, its opportunistic scavenging abilities have led to its success and numerical superiority on the shallow subtidal sands of Lobster Bay. The dominance of E. contractus in Lobster Bay, and elsewhere in Hong Kong, is unusual. Here, the normally predatory E. contractus, far outnumbers all other scavengers, possibly because of an enhanced, largely allochthonous, supply of food which it is able to exploit by virtue of its previously identified opportunistic habit of scavenging the leftovers of other predators. The presence of inter-specific competition between E. contractus and a sympatric suite of nassariids enhances, not impedes, carrion exploitation.

An Approach to Modeling Crustacean Egg-Bearing Fractions as a Function of Size and Season

1991 ◽  
Vol 48 (8) ◽  
pp. 1431-1436 ◽  
Author(s):  
Victor R. Restrepo ◽  
Reg A. Watson
Keyword(s):  
Egg Production ◽  
Logistic Function ◽  
Parameter Estimates ◽  
Seasonal Trends ◽  
Basic Model ◽  
Maximum Likelihood Methods ◽  
Temperature Parameter ◽  
Gravid Females ◽  
The Individual ◽  
The Relationship

We present an approach to the analysis of crustacean egg production ogives with emphasis on detecting seasonal trends. The relationship between the proportion of gravid females (by size) and season is a prerequisite to the estimation of egg production potentials of populations. The basic method consists of relating, for each sample, the proportion of berried females with their size through a three-parameter logistic function where the asymptote may be less than 1. We then provide guidance for detecting seasonal trends in the estimates of the parameters for the individual samples. This is accomplished by restricting the basic model such that some parameters are considered to be either fixed for all samples or as simple functions of time or environmental variables such as temperature. Parameter estimates are obtained via maximum likelihood methods, and comparisons between alternative models are presented graphically and using likelihood ratio tests. We illustrate the approach and its application with data for a tropical shrimp, Penaeus esculentus, from northern Australia.

Grazing by the gastropod, Lacuna vincta, in the lower intertidal area at Musquash Head, New Brunswick, Canada

1983 ◽  
Vol 63 (3) ◽  
pp. 725-736 ◽  
Author(s):  
Martin L. H. Thomas ◽  
Frederick H. Page
Keyword(s):  
New Brunswick ◽  
Egg Production ◽  
Algal Species ◽  
Egg Mass ◽  
Intertidal Area ◽  
Mass Distributions ◽  
Lacuna Vincta ◽  
Egg Deposition ◽  
Large Numbers ◽  
The Impact

Lacuna vincta appeared at Musquash Head, New Brunswick, in large numbers from June to August 1981 principally on lower midlittoral and infralittoral fringe Fucus edentatus. The population reached a mean maximum of 280/m2 in June; by mid September the animals had disappeared. The L. vincta grazed heavily and deposited egg masses on Fucus edentatus but little on other species. All fine and filamentous and encrusting algal species and rock were avoided for egg deposition. Egg mass abundance peaked with the population in June with a mean of 180/m2. Mean egg production in June was 83000/m2.Both snail and egg mass distributions were correlated with the percentage cover of F. edentatus, reaching a maximum at 40–75 cm above mean low tide level.The snails ranged in length from 2–7 mm, consisting of three cohorts from different larval settlements. Growth was rapid in July averaging 0·6 mm/month slowing later.The food plant Fucus edentatus showed a heavy impact of the herbivore. Weight reductions attributable to grazing rose from 56 % in June to 79 % in August and grazed plants tended to thicken rather than elongate with growth. Grazing removed about 79 % of the net production of F. edentatus which averaged 61 g dry wt/m2/day. The impact of the L. vincta population on F. edentatus seems extraordinarily severe.

Brevibucca frugicola n. sp., a saprophagous nematode found in a rotting peach fruit.

1942 ◽  
Vol 20 (1-2) ◽  
pp. 1-5 ◽  
Author(s):  
T. Goodey
Keyword(s):  
Fruit Flies ◽  
Adult Males ◽  
Department Of Agriculture ◽  
Peach Fruit ◽  
Large Numbers ◽  
Structural Details ◽  
Males And Females

Early in 1938 the writer received a tube of nematodes from Mr. Colin Smee, Entomologist, Department of Agriculture, Zomba, Nyasaland, collected from a rotting peach fruit in which he had been trying to hatch fruit-flies. According to Mr. Smee's letter the worms had formed masses in the fruit and had also appeared on the surface as waving threads or tendrils composed of numerous eelworms massed together. The material had been fixed in glycerine alcohol and consisted of numerous adult males and females as well as large numbers of larval forms. Fixation was not good as although the gross morphology and anatomy was fairly easily discernible, some of the finer structural details were not as clear as one could have wished.

scholarly journals Giant Water Bugs, Electric Light Bugs, Lethocerus, Abedus, Belostoma (Insecta: Heteroptera: Belostomatidae)

EDIS ◽  
1969 ◽  
Vol 2005 (1) ◽  
Author(s):  
Paul M. Choate
Keyword(s):  
Aquatic Insects ◽  
Cooperative Extension Service ◽  
Small Fish ◽  
South American ◽  
South American Species ◽  
University Of Florida ◽  
Large Numbers ◽  
Abdominal Appendages ◽  
Electric Light ◽  
Water Bugs

The heteropteran family Belostomatidae contains the giant water bugs. These large, predatory, aquatic insects have the largest body size among the Heteroptera. Adults of some South American species reach 4 inches in length. Individuals occur in ponds and ditches where they suspend below the surface, respiring through two abdominal appendages which act as siphons. During mating season they fly from pond to pond or pool of water. It is during these flights that these insects fly to lights in large numbers, earning their other common name, "electric light bugs". Individuals are capable of inflicting a painful bite with their strong beak, and may also pinch with their front legs. Individuals prey on aquatic insects, small fish, frogs, tadpoles, small birds, and other organisms they are able to capture. Powerful enzymes are injected into prey to kill them. Adults of Lethocerus are considered a delicacy in Asia, and are eaten both fresh and cooked. This document is EENY-301, one of a series of Featured Creatures from the Entomology and Nematology Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Published: July 2003. Revised: October 2003. EENY-301/IN578: Giant Water Bugs, Electric Light Bugs, Lethocerus, Abedus, Belostoma (Insecta: Hemiptera: Belostomatidae) (ufl.edu)

scholarly journals All day-long: Sticklebacks effectively forage on whitefish eggs during all light conditions

PLoS ONE ◽  
2021 ◽  
Vol 16 (8) ◽  
pp. e0255497
Author(s):  
Jan Baer ◽  
Sarah Maria Gugele ◽  
Joachim Bretzel ◽  
J. Tyrell DeWeber ◽  
Alexander Brinker
Keyword(s):  
Egg Production ◽  
Gasterosteus Aculeatus ◽  
Energy Content ◽  
Stomach Content Analysis ◽  
Pelagic Zone ◽  
Light Conditions ◽  
Egg Predation ◽  
Large Numbers ◽  
Potential Benefits ◽  
Freshwater Stickleback

The three-spined stickleback Gasterosteus aculeatus invaded Lake Contance in the 1940s and expanded in large numbers from an exclusively shoreline habitat into the pelagic zone in 2012. Stickleback abundance is very high in the pelagic zone in winter near the spawning time of pelagic whitefish Coregonus wartmanni, and it is hypothesized that this is triggered by the opportunity to consume whitefish eggs. Field sampling has qualitatively confirmed predation of whitefish eggs by stickleback, but quantification has proven difficult due to stormy conditions that limit sampling. One fundamental unknown is if freshwater stickleback, known as visual feeders, can successfully find and eat whitefish eggs during twilight and night when whitefish spawn. It is also unknown how long eggs can be identified in stomachs following ingestion, which could limit efforts to quantify egg predation through stomach content analysis. To answer these questions, 144 individuals were given the opportunity to feed on whitefish roe under daylight, twilight, and darkness in controlled conditions. The results showed that stickleback can ingest as many as 100 whitefish eggs under any light conditions, and some individuals even consumed maximum numbers in complete darkness. Furthermore, eggs could be unambiguously identified in the stomach 24 hours after consumption. Whitefish eggs have 28% more energy content than the main diet of sticklebacks (zooplankton) based on bomb-calorimetric measurements, underlining the potential benefits of consuming eggs. Based on experimental results and estimates of stickleback abundance and total egg production, stickleback could potentially consume substantial proportions of the total eggs produced even if relatively few sticklebacks consume eggs. Given the evidence that stickleback can feed on eggs during nighttime spawning and may thereby hamper recruitment, future studies aimed at quantifying actual egg predation and resulting effects on the whitefish population are urgently needed.

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