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.

Spatial and Temporal Overlap of the American Lobster (Homarus americanus) and Sea Scallop (Placopecten magellanicus) as Related to the impact of Inshore Scallop Dragging

1992 ◽  
Vol 49 (7) ◽  
pp. 1486-1492 ◽  
Author(s):  
D. L. Roddick ◽  
R. J. Miller
Keyword(s):  
Nova Scotia ◽  
Homarus Americanus ◽  
Fishing Effort ◽  
The Other ◽  
American Lobster ◽  
Placopecten Magellanicus ◽  
Time And Space ◽  
Sea Scallop ◽  
The Impact ◽  
Temporal Overlap

Assessment of the damage of one fishery by another requires knowledge of the overlap, in time and space, of the damaging fishing effort and the abundance of the damaged species, as well as a measure of the rate of damage. This approach was used to measure the impact of inshore scallop dragging on lobsters in Nova Scotia. Areas of reported co-occurrence of lobster and scallop grounds were surveyed by divers to determine the extent of overlap. Only 2 of 52 sites surveyed had lobsters on scallop grounds that could be dragged. Divers surveyed one site six times during 1987 and 1988 and found lobsters most abundant during August and September. Only 2% of the lobsters in the path of scallop drags were either captured or injured. The estimated value of lobsters destroyed by dragging for scallops during periods of peak lobster abundance was minor: $757 at one site and $176 at the other. Restricting dragging to periods of low lobster abundance significantly reduces this cost.

Historical Review of Lobster Life History Terminology and Proposed Modifications To Current Schemes

Crustaceana ◽  
1996 ◽  
Vol 69 (5) ◽  
pp. 594-609 ◽  
Author(s):  
Peter Lawton ◽  
Kari L. Lavalli
Keyword(s):  
Life History ◽  
Size Range ◽  
Historical Review ◽  
Homarus Americanus ◽  
Behavioral Changes ◽  
American Lobster ◽  
Behavioral Attributes ◽  
Developmental Phases ◽  
The Impact ◽  
Current Terminology

AbstractTerms for the life history and developmental phases of the American lobster, Homarus americanus, vary substantially and have been frequently revised (Cobb et al., 1983; Hudon, 1987; Barshaw & Bryant-Rich, 1988; Wahle & Steneck, 1991; Cobb & Wahle, 1994). Their evolution shows several trends: (1) acknowledgement of pronounced morphological, physiological, and behavioral changes accompanying a metamorphic molt into the fourth pelagic stage; (2) recognition of behavioral changes (facilitated by decreasing mortality risk) leading to increased vagility over the size range ~ 5 to 40 mm carapace length (CL), and (3) consideration of the impact of reproductive maturation on lobster movement and social interaction. Before further modifying current terminological schemes (Wahle & Steneck, 1991; Cobb & Wahle, 1994), a historical perspective is provided and problems with existing schemes are presented. Our proposed scheme, which better integrates ecological ontogeny with developmental, biological, and individual behavioral attributes, partitions the life history into seven phases (exclusive of the attached egg and prelarval stages): pelagic larval, postlarval, shelter-restricted juvenile, emergent juvenile, vagile juvenile, adolescent, and adult. It should also provide a template from which to standardize life history schemes for spiny lobsters where there are similar problems with current terminology.

Egg Loss from the American Lobster, Homarus americanus, in Relation to Nemertean, Pseudocarcinonemertes homari, Infestation

1986 ◽  
Vol 43 (4) ◽  
pp. 772-780 ◽  
Author(s):  
Alan Campbell ◽  
John Brattey
Keyword(s):  
New Brunswick ◽  
Homarus Americanus ◽  
Egg Mass ◽  
American Lobster ◽  
Mass Destruction ◽  
Egg Incubation ◽  
Early Stages ◽  
Low Correlation ◽  
Incubation Periods ◽  
The Relationship

The relationship between nemertean (Pseudocarcinonemertes homari) infestaton and egg loss from ovigerous American lobsters, Homarus americanus, trapped near Grand Manan, New Brunswick, was investigated during 1980–83. The proportion of lobster eggs lost each month was variable, but generally increased to a maximum of 0.38–0.43 at the end of each of the three egg incubation periods. Up to 6.3% of the newly ovigerous lobsters tagged (N = 1413) during July–October 1982 has lost all their eggs by April–July 1983. Most ovigerous lobsters (74%) were infested with P. homari, but many lobsters had low mean densities of nemerteans (< 2/1000 lobster eggs). There was a significant but low correlation between P. homari densities and the proportion of eggs lost; however, egg losses could not be attributed solely to P. homari. Egg loss did not differ significantly between uninfested and nemertean-infested lobsters during each of the three egg incubation periods. The few lobsters that acquired high densities (> 4) of P. homari during the early stages of egg incubation appeared to suffer extensive or complete egg mass destruction. However, most lobsters maintained low densities (< 2) of nemerteans and hatched most (> 60%) of their eggs.

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.

Morphology and Systematics of the Nemertean Pseudocarcinonemertes homari (Hoplonemertea:Mortostilifera) from the American Lobster, Homarus americanus

1985 ◽  
Vol 42 (2) ◽  
pp. 342-350 ◽  
Author(s):  
L. S. Uhazy ◽  
D. E. Aiken ◽  
A. Campbell
Keyword(s):  
Developmental Stages ◽  
Morphological Characteristics ◽  
Original Description ◽  
Homarus Americanus ◽  
Bay Of Fundy ◽  
American Lobster ◽  
Free Living ◽  
The Family ◽  
Passamaquoddy Bay ◽  
Stylet Length

Our study of the morphology and systematics of the nemertean Pseudocarcinonemertes homari Fleming and Gibson, 1981 is based on specimens removed from the damaged egg masses of American lobsters, Homarus americanus, caught in the type locality at Grand Manan, N.B., in the Bay of Fundy and nearby Passamaquoddy Bay. Morphological characteristics and measurements of males, females, and developmental stages, obtained through examination of live and preserved nemerteans plus stained histological sections, revealed differences and provided additional indications of variability in measurements of taxonomic characters when compared with the original description. Specifically, female nemerteans are longer and slightly wider than males; the rhynchodael opening is subterminal; sensory bristles occur lateral to the rhynchodael and anal openings; cephalic furrows are observable on living specimens; the combined stylet–basis length is longer than reported and stylet length appears a stable character; the bulbous or sacculate foregut joins to a distinct pyloric tube; ova are large, 260 × 251 μm in length and width; and larvae retained in the membranous brood sac lack anterior and posterior cirri or tufts. Comparison of characters that define Pseudocarcinonemertes and differentiate it from Carcinonemertes with those defining free-living hoplonemerteans strongly supports its removal from the family Carcinonemertidae to the family Tetrastemmatidae.

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.

Declining fecundity and factors affecting embryo quality in the American lobster (Homarus americanus) from the Bay of Fundy

2015 ◽  
Vol 72 (3) ◽  
pp. 352-363 ◽  
Author(s):  
Heather N. Koopman ◽  
Andrew J. Westgate ◽  
Zachary A. Siders
Keyword(s):  
Embryo Quality ◽  
Gulf Of Maine ◽  
Energy Content ◽  
Homarus Americanus ◽  
Striking Difference ◽  
Bay Of Fundy ◽  
American Lobster ◽  
Female Size ◽  
Factors Affecting ◽  
Old Females

Recent perturbations in ecosystem and environmental dynamics in the habitat of the American lobster have led to increases in abundance, with unprecedented high landings in some regions. Despite the commercial value of this species, surprisingly little is known about maternal and environmental influences on its reproductive output. We measured fecundity and embryo quality in 1370 ovigerous lobsters from the Bay of Fundy, Canada, during 2008–2013. Female size was generally positively correlated with fecundity (P < 0.001), although some of the very large (and presumably old) females brooded significantly fewer eggs than expected. Egg energy content and lipid content and composition exhibited significant annual differences, indicating environmentally based variation. The most striking difference was a 31% decline in fecundity from 2008 to 2013 (8%–10% per year). We hypothesize that recent warming trends could be responsible for reduced fecundity. Decreased fecundity may be a cause for concern for future recruitment in this population, which has been shown to be an important source of larvae for the Gulf of Maine metapopulation.

Evidence that mud seafloor serves as recruitment habitat for settling and early benthic phase of the American lobster Homarus americanus H. Milne Edwards, 1837 (Decapoda: Astacidea: Nephropidae)

2019 ◽  
Vol 39 (5) ◽  
pp. 594-601
Author(s):  
Kristin M Dinning ◽  
Rémy Rochette
Keyword(s):  
Body Condition ◽  
Relative Abundance ◽  
Size Range ◽  
Homarus Americanus ◽  
Bay Of Fundy ◽  
American Lobster ◽  
Differential Growth ◽  
The Past ◽  
Current Potential ◽  
Important Habitat

Abstract Structurally complex cobble seafloor protects against predators, and is generally assumed to be the only meaningful habitat for settlement and benthic recruitment of American lobsters (Homarus americanus H. Milne Edwards, 1837). Accordingly, historical surveys on featureless substrates such as mud have found few and only older juveniles. Mud, however, is far more common than cobble across the lobster’s range, and may be of increasing importance in regions where the lobster population has been growing over the past few decades. As a first step to determining whether mud seafloor serves as meaningful recruitment habitat for juvenile lobsters, we deployed artificial habitats (bio-collectors) at five locations varying from 100% mud to mostly cobble, in Maces Bay, Bay of Fundy, NB, Canada, to capture young lobsters. A broad size range of lobsters, from new settlers up to adolescents, colonized bio-collectors in all locations, suggesting that lobsters settle and spend at least some of their juvenile life on mud. Differences in body condition (length-standardized mass) of lobsters sampled from the different locations suggest that some individuals must reside on mud for at least months to years, long enough to show differential growth between habitats. The greater relative abundance of adolescents in bio-collectors on mud also suggests their net movement from densely populated cobble beds into mud habitat. We propose that mud seafloor may be a more important habitat for settlement and early survival of American lobsters than is currently appreciated, especially given the current potential saturation of scarce cobble nursery habitat by growing lobster populations and, in some regions, reduced predation on mud seafloor due to overfishing of groundfish.

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