Salinity Tolerance and Osmoregulation in the Nemertean Pseudocarcinonemertes homari, an Egg Predator of American Lobster, Homarus americanus

1991 ◽  
Vol 48 (2) ◽  
pp. 209-214 ◽  
Author(s):  
G. Charmantier ◽  
M. Charmantier-Daures ◽  
S. L. Waddy ◽  
D. E. Aiken
Keyword(s):  
Salinity Tolerance ◽  
Stage Iv ◽  
Homarus Americanus ◽  
Index Formula ◽  
American Lobster ◽  
Egg Masses ◽  
Egg Predator

The salinity tolerance and osmoregulation of Pseudocarcinonemertes homari were determined to develop a method for elimination of this nemertean from egg masses of American lobster, Homarus americanus. The lower and upper lethal salinities (LS50) for nemerteans are 11 and 45‰ at 7 °C and 19 and 37‰ at 14.5 °C. Immersion in freshwater was lethal in 4 min or less, depending on temperature. The nemerteans hyperosmoconformed over the range 10–1600 mosm∙kg−1. Lobster eggs (eye index [Formula: see text]) survived for 2–8 h when immersed in freshwater. Ovigerous lobster were not affected by a 5-min immersion in freshwater and were able to withstand at least 30 min if only the abdomen was immersed. Lobster eggs hatched and larvae developed normally up to at least stage IV, even after a 30-min freshwater immersion. These results suggest that nemerteans could be eliminated from American lobster by immersing their abdomen and attached eggs in freshwater for 5 min and immersing the entire lobster for an additional 5 min.

Effect of Temperature on the Behavior of Stage IV American Lobster (Homarus americanus) Larvae

2015 ◽  
Vol 34 (2) ◽  
pp. 545-554 ◽  
Author(s):  
Melanie Chiasson ◽  
Gilles Miron ◽  
Dounia Daoud ◽  
Martin D. Mallet
Keyword(s):  
Stage Iv ◽  
Homarus Americanus ◽  
Effect Of Temperature ◽  
American Lobster

scholarly journals Linking rising pCO2 and temperature to the larval development and physiology of the American lobster (Homarus americanus)

2016 ◽  
Vol 74 (4) ◽  
pp. 1210-1219 ◽  
Author(s):  
Jesica D. Waller ◽  
Richard A. Wahle ◽  
Halley McVeigh ◽  
David M. Fields
Keyword(s):  
Climate Change ◽  
Larval Development ◽  
Stage Iv ◽  
Homarus Americanus ◽  
Larval Survival ◽  
Interactive Effects ◽  
High Pco2 ◽  
American Lobster ◽  
Feeding Rates ◽  
Intergovernmental Panel

Few studies have evaluated the joint effects of elevated temperature and pCO2 on marine organisms. In this study we investigated the interactive effects of Intergovernmental Panel on Climate Change predicted temperature and pCO2 for the end of the 21st century on key aspects of larval development of the American lobster, Homarus americanus, an otherwise well-studied, iconic, and commercially prominent species in the northeastern United States and Atlantic Canada. Our experiments showed that larvae (stages I–III) and postlarvae (stage IV) reared in the high temperature treatments (19 °C) experienced significantly lower survival, developed twice as fast, and had significantly higher oxygen consumption rates, than those in ambient treatments (16 °C). Larvae from the ambient temperature/high pCO2 (750 ppm) treatment had significantly longer carapace lengths, greater dry masses in stages I–III and higher C: N ratios in stage IV than larvae from all other treatments. Stage IVs raised in the high pCO2 treatment at 19 °C had significantly higher feeding rates and swimming speeds than stage IVs from the other three treatments. Together these results suggest that projected end-century warming will have greater adverse effects than increased pCO2 on larval survival, and changing pCO2 may have a complex effect on larval metabolism and behaviour. Understanding how the most vulnerable life stages of the lobster life cycle respond to climate change is essential in connecting the northward geographic shifts projected by habitat quality models, and the underlying physiological and genetic mechanisms that drive their ecology.

Swimming Ability of Larval American Lobsters, Homarus americanus, in Flowing Water

1986 ◽  
Vol 43 (11) ◽  
pp. 2177-2183 ◽  
Author(s):  
G. P. Ennis
Keyword(s):  
Stage Iv ◽  
Homarus Americanus ◽  
American Lobster ◽  
Flowing Water ◽  
Swimming Ability ◽  
Flow Rates ◽  
Larval Stages ◽  
Upstream Direction ◽  
Swimming Capacity ◽  
Observation Period

The swimming capacity of American lobster, Homarus americanus, larvae in flowing water was observed in a screened-off portion of a flow tank. At a flow rate of 2 cm∙s−1, stage I–III larvae were swimming for 46–74% of the observations during the first 5 min but this ranged from 0 to 28% toward the end of a 30-min period. At higher flow rates, however, very few of these larvae were able to continue swimming longer than 5 min. Newly molted stage IV larvae displayed substantially improved swimming ability compared with earlier stages. At 2 cm∙s−1, these larvae were swimming for 40–48% of the observations over the 30-min period, although at higher flow rates their capacity to continue swimming was also limited and few were observed swimming longer than 10 min. Older stage IV larvae were more capable swimmers than newly molted stage IV larvae and displayed a capacity to continue swimming over the 30-min observation period at flow rates up to 9 cm∙s−1. In flowing water, the frequency of orientation in the upstream direction for larvae that were swimming was higher than for control larvae. For stage IV larvae especially, this frequency was higher at the higher flow rates. The observations demonstrate the presence of a rheotactic response in all larval stages of the American lobster. The response is relatively weak in stages I–III but strong in stage IV.

Behavior and Distribution of Larval and Early Jevenile Homarus americanus

1983 ◽  
Vol 40 (12) ◽  
pp. 2184-2188 ◽  
Author(s):  
J. S. Cobb ◽  
T. Gulbransen ◽  
B. F. Phillips ◽  
D. Wang ◽  
M. Syslo
Keyword(s):  
Stage Iv ◽  
Homarus Americanus ◽  
American Lobster ◽  
Substrate Selection ◽  
Fourth Stage ◽  
Shallow Sea ◽  
Behavioral Observations

Field behavioral observations and plankton tows show that American lobster (Homarus americanus) larvae are concentrated in downwellings characteristic of shallow sea fronts. Stage IV lobsters swimming at the surface avoided floating weeds and sticks. Seventy percent of laboratory-reared fourth stage lobsters swam near the surface for more than a minute when released but only 25% of fifth stage lobsters did so. When early fourth stage lobsters encountered bottom, they did not remain long in one place, but late fourth and early fifth stage lobsters began to burrow. Late fourth and early fifth stage lobsters were less likely to return to the surface when they reached the bottom. If the bottom was unsuitable (featureless sand), the lobsters resumed swimming. These behaviors appear to be an appropriate mechanism for substrate selection during settlement.

scholarly journals Larval Development of the European Lobster and How Small Heterochronic Shifts Lead to a More Pronounced Metamorphosis

2015 ◽  
Vol 2015 ◽  
pp. 1-17 ◽  
Author(s):  
Marie A. I. N. Rötzer ◽  
Joachim T. Haug
Keyword(s):  
Larval Stage ◽  
Stage Iv ◽  
Extreme Case ◽  
Homarus Americanus ◽  
Stage Iii ◽  
American Lobster ◽  
Factors Affecting ◽  
European Lobster ◽  
Larval Stages ◽  
Two Factors

We redescribe the larval stages of the European lobster,Homarus gammarus, based on autofluorescence composite imaging. We focus on larval stages (II) to (IV). Compared to the American lobster,Homarus americanus, differences are most apparent in stage (III). This stage appears more mature inH. gammarus; for example, the rostrum is already curved and bears spines, and the appendages are better developed and longer and more differentiated. InH. americanusstage (III) shows a stronger resemblance to stage (II). As a result of the morphology of stage (III), the “metamorphic” moult between stage (III) and stage (IV) inH. gammarusis less drastic than inH. americanus. Metamorphosis is characterised by two criteria. It involves (1) a drastic change in morphology in (2) a short amount of time. It has hence been suggested that a more pronounced metamorphosis evolves by two factors affecting these criteria, namely, (1) the evolution of specialised larval features, which increase the morphological disparity between larva and adult that makes the change of morphology more drastic, and (2) the skipping of entire stages. This means larval forms ancestrally moult over several intermediate forms into the definite adult morphology. Yet, in more derived forms the stages with intermediate morphologies are no longer expressed; highly specialized larvae moult into the adult within a single moult (in the most extreme case) hence bridging the morphologies of larvae and adult in a shorter amount of time. The example of the twoHomarusspecies demonstrates that this explanation is not the only possible one. Additionally, differences of a single larval stage (in this case larval stage (III)) can lead to a more or less metamorphic-appearing ontogenetic sequence.

Recruitment Dynamics in an American Lobster (Homarus americanus) Population

1986 ◽  
Vol 43 (11) ◽  
pp. 2368-2376 ◽  
Author(s):  
Michael J. Fogarty ◽  
Josef S. Idoine
Keyword(s):  
Larval Settlement ◽  
Stage Iv ◽  
Homarus Americanus ◽  
American Lobster ◽  
Control Analysis ◽  
Larval Phase ◽  
Density Dependent ◽  
Larval Production ◽  
Asymptotic Relationship ◽  
Density Dependent Regulation

We examined relationships between successive life history stages of an American lobster (Homarus americanus) population for evidence of density-dependent control. Analysis of a time series of larval production estimates for the Northumberland Strait region of the southern Gulf of St. Lawrence during 1949–63 (D. J. Scarratt. 1964. J. Fish. Res. Board Can. 21: 661–680; D. J. Scarratt. 1973. J. Fish. Res. Board Can. 30: 1819–1824) provided no indication of density-dependent regulation during the pelagic larval phase. However, an asymptotic relationship between the final (fourth) larval stage and stock size 5–7 yr later was demonstrated, indicating the possibility of density-dependent regulation between larval settlement and subsequent recruitment to the fishery. A second analysis supported these results based on trends in population size over several generations. A recruitment mechanism of this type is highly stabilizing and can explain the apparent capacity of lobster populations to sustain high levels of fishing mortality. The postulated recruitment mechanism for Northumberland Strait lobsters may reflect competition for critical resources. We propose that shelter is an important limiting resource and that shelter competition experiments be undertaken in the field and laboratory to test this hypothesis. Finally, we demonstrate the use of a multistage recruitment model which accounts for the general form of observed interstage relationships. The asymptotic relationship between stage IV production and subsequent stock results in a stable population which is resilient to exploitation.

Geographic Distribution and Seasonal Occurrence of the Nemertean Pseudocarcinonemertes homari on the American Lobster, Homarus americanus

1985 ◽  
Vol 42 (2) ◽  
pp. 360-367 ◽  
Author(s):  
J. Brattey ◽  
A. Campbell ◽  
A. E. Bagnall ◽  
L. S. Uhazy
Keyword(s):  
Homarus Americanus ◽  
Bay Of Fundy ◽  
American Lobster ◽  
Wild Populations ◽  
Intensity Of Infection ◽  
Egg Masses ◽  
Mean Intensity ◽  
Life History Stages ◽  
Egg Incubation ◽  
The Impact

Examination of 1041 trap-caught lobsters from the Bay of Fundy, Grand Manan, Browns and German Banks, south and east Nova Scotia, and Northumberland Strait indicated that Pseudocarcinonemertes homari occurs on American lobsters, Homarus americanus, throughout Canadian Maritime waters. Male lobsters were rarely infected and ovigerous females generally had a higher prevalence (percentage infected) and mean intensity of infection (number of nemerteans per infected lobster) than nonovigerous females. Sexually immature nemerteans were found on male and nonovigerous female lobsters, but all P. homari life history stages including brood sacs occurred on ovigerous lobsters. No seasonal trends were evident on ovigerous lobsters caught near Grand Manan; prevalence was consistently high (60–93%) and mean intensity ± SE was variable (15 ± 4.0 to 86 ± 63.1). The nemertean developed to maturity on ovigerous lobsters, reproduced on the host egg masses throughout the year, and appeared to produce three generations during a lobster egg incubation period. When lobsters completed egg incubation, nemertean reproduction ceased and some nemerteans either died, left the lobster, or perhaps were shed at molting. Prevalence and mean intensity increased with the size of ovigerous lobsters, and the distribution of nemerteans among ovigerous lobsters was highly aggregated. Ovigerous lobsters infected with >200 nemerteans had extensively damaged egg masses, but were rarely encountered (5 of 291). The impact of P. homari on the egg mortality of wild populations of H. americanus is unknown.

Occurrence of Histriobdella homari (Annelida: Polychaeta) on the American lobster in the Canadian Maritimes

1985 ◽  
Vol 63 (2) ◽  
pp. 392-395 ◽  
Author(s):  
John Brattey ◽  
Alan Campbell
Keyword(s):  
Homarus Americanus ◽  
High Abundance ◽  
American Lobster ◽  
Egg Hatching ◽  
Egg Masses ◽  
Beneficial Effects ◽  
Gill Filaments

Examination of 870 trap-caught lobsters, Homarus americanus, indicated that Histriobdella homari, an epizoic microphagous cleaning symbiont, was common and widely distributed on lobster populations in Canadian Maritime waters during 1980–1981. Prevalence (percent lobsters infected) and abundance (mean number of H. homari per lobster) ranged from 39.6 to 100% and 4.8 to 80.5, respectively. The polychaete was more abundant on ovigerous females than on male or nonovigerous female lobsters. The distribution of H. homari among lobsters was aggregated with a maximum of 669 H. homari on a lobster. In most infestations, the polychaete is probably beneficial to the lobster by removing encrusting microorganisms from the gill filaments and egg masses. However, on the few lobsters that have high abundance of greater than 200 H. homari per individual, the beneficial effects may be lost, since the polychaetes may reduce repiratory flow and success of egg hatching.

Nutritional and Bioenergetic Considerations in the Development of the American Lobster Homarus americanus

1986 ◽  
Vol 43 (11) ◽  
pp. 2311-2319 ◽  
Author(s):  
Glenn C. Sasaki ◽  
Judith McDowell Capuzzo ◽  
Patricia Biesiot
Keyword(s):  
Elevated Temperatures ◽  
Food Selection ◽  
Stage Iv ◽  
Homarus Americanus ◽  
American Lobster ◽  
Midgut Gland ◽  
Juvenile Form ◽  
Biochemical Processes ◽  
Larval Stages ◽  
Physiological And Biochemical

To better understand the early life history stages of the American lobster Homarus americanus, nutritional and bioenergetic aspects of development have been investigated. These studies focused on physiological and biochemical processes during transitional periods between extrusion of the eggs, hatching, larval development, molting, metamorphosis, and attainment of the juvenile stage. Biochemical changes during embryogenesis reflect catabolism of various substrates for energy. Exposure to different thermal regimes resulted in considerable variation in the rates of utilization of energy substrates during embryogenesis. Embryos raised at elevated temperatures had yolk remaining at the time of hatching. The first three larval stages have similar energy requirements. Lipid is of prime importance and the turnover rate for lipid can be rapid. Weight-specific metabolism increases with successive larval stages, in stage IV lobsters, the dependency on lipid as a substrate is diminished and lipid reserves serve a storage function. Metabolic rates of premolt stage IV lobsters are decreased in comparison with earlier stages. These changes in physiology correlate with changes in the developing midgut gland, specifically with the appearance of droplets of lipid in the lipid-storing cells of the midgut gland of stage IV lobsters. By stage VI, lobsters have energy storage and metabolic patterns similar to those of adults, and the midgut gland has the adult morphology. The transitions from hatching to attainment of the juvenile form are reflected in differences in physiological and biochemical processes that influence food selection and diet.

Effects of Time of Day, Water Temperature, and Water Velocity on Swimming by Postlarvae of the American Lobster, Homarus americanus

1991 ◽  
Vol 48 (10) ◽  
pp. 1944-1950 ◽  
Author(s):  
Patricia Rooney ◽  
J. Stanley Cobb
Keyword(s):  
Water Temperature ◽  
Larval Stage ◽  
Stage Iv ◽  
Homarus Americanus ◽  
Time Of Day ◽  
Water Velocity ◽  
Swimming Behavior ◽  
American Lobster ◽  
Swimming Mode

Swimming speeds and swimming behavior of laboratory-reared and wild postlarvae (larval stage IV) of the American lobster, Homarus americanus, were observed in tanks of still water and in a linear flume. Mean swimming speeds ranged from about 7 cm∙s−1 in the "claws-apart" swimming mode to 13.2 cm∙s−1 in the streamlined, "claws-together" mode. In the flume, the total time spent swimming during a 30-min test period decreased as water velocity increased from 8 to 14 cm∙s−1. The time spent swimming was greater during the day than at either dusk or night. Postlarvae spent very little time swimming at 15 °C but significantly more at 21 °C. Wild postlarvae were larger, heavier, and swam more rapidly than laboratory-reared postlarvae. Rapid, directional swimming by postlarval lobsters may play a role in determination of distribution and recruitment to benthic populations.

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