Sex ratios of Corophium volutator (Pallas) (Crustacea: Amphipoda) in Bay of Fundy populations

1994 ◽  
Vol 72 (11) ◽  
pp. 1915-1921 ◽  
Author(s):  
Saul D. Schneider ◽  
J. Sherman Boates ◽  
Mark Forbes
Keyword(s):  
Prey Species ◽  
Sex Ratios ◽  
Accurate Method ◽  
Bay Of Fundy ◽  
Adult Males ◽  
Corophium Volutator ◽  
Important Prey ◽  
Differential Predation ◽  
History Of ◽  
Biased Sex Ratio

Previous work on the tube-dwelling intertidal amphipod Corophium volutator (Pallas) has shown that adult sex ratios are female-biased for populations along the Bay of Fundy, Canada. The causes of these biased sex ratios, and many other aspects of the life history of this important prey species, are unknown. Some authors have suggested that biased sex ratios for adults may be due to differential predation on adult males by migrant shorebirds. Such differential predation is not expected for juvenile C. volutator, which differ in behaviour from adult males. In this study, we first demonstrate an accurate method of sexing juvenile C. volutator that is based on sex differences shown by adults. This method will enable more detailed ecological studies of C. volutator. We then show that sex ratios are female-biased for juvenile C. volutator, which is probably a more important determinant of a biased sex ratio for adults than is differential shorebird predation on adult males. We demonstrate that biased sex ratios also appear to occur for newly hatched C. volutator, indicating that some form of asexual reproduction (e.g., automixis) may exist within Bay of Fundy populations of C. volutator.

Integration of Ecological and Engineering Aspects in Planning Large Scale Tidal Power Development in the Bay of Fundy, Canada

1984 ◽  
Vol 16 (1-2) ◽  
pp. 281-295 ◽  
Author(s):  
Donald C Gordon
Keyword(s):  
Large Scale ◽  
Feasibility Studies ◽  
Bay Of Fundy ◽  
Final Decision ◽  
Power Development ◽  
Tidal Power ◽  
History Of ◽  
Scientists And Engineers ◽  
The Many ◽  
University Scientists

Large-scale tidal power development in the Bay of Fundy has been given serious consideration for over 60 years. There has been a long history of productive interaction between environmental scientists and engineers durinn the many feasibility studies undertaken. Up until recently, tidal power proposals were dropped on economic grounds. However, large-scale development in the upper reaches of the Bay of Fundy now appears to be economically viable and a pre-commitment design program is highly likely in the near future. A large number of basic scientific research studies have been and are being conducted by government and university scientists. Likely environmental impacts have been examined by scientists and engineers together in a preliminary fashion on several occasions. A full environmental assessment will be conducted before a final decision is made and the results will definately influence the outcome.

Diet

2017 ◽  
Author(s):  
M.G.L. Mills ◽  
M.E.J. Mills
Keyword(s):  
Prey Species ◽  
Radio Tracking ◽  
Relative Occurrence ◽  
Important Prey ◽  
Individual Prey ◽  
Sibling Groups

Four methods were used to document the diet of cheetahs: incidental observations, radio tracking, tracking, spoor, and continuous follows. A combination of continuous follows and tracking spoor gave the best results. Steenbok were the most frequently killed species, but they did not dominate the diet in the same way as Thomson’s gazelle do in the Serengeti. Coalition males have a different diet profile from single males, single females, females with cubs, and sibling groups. For all but single males, the relative occurrence of prey species in the diet reflected its dietary importance in terms of kilograms of meat obtained. Gemsbok calves and adult ostrich were important prey for coalition males and springhares were important for single males. Three individual prey specializations for females were found; namely springbok specialists, steenbok/duiker specialists, and intermediates. Contrary to an earlier study, springbok were not found to be the most important prey species.

scholarly journals Prey consumed by Guiana dolphin Sotalia guianensis (Cetacea, Delphinidae) and franciscana dolphin Pontoporia blainvillei (Cetacea, Pontoporiidae) in an estuarine environment in southern Brazil

2012 ◽  
Vol 102 (2) ◽  
pp. 131-137 ◽  
Author(s):  
Marta J. Cremer ◽  
Pedro C. Pinheiro ◽  
Paulo C. Simões-Lopes
Keyword(s):  
Prey Species ◽  
Stomach Contents ◽  
Frequency Of Occurrence ◽  
Teleost Fishes ◽  
Southern Brazil ◽  
Sympatric Populations ◽  
Sotalia Guianensis ◽  
Important Prey ◽  
Pontoporia Blainvillei ◽  
Lolliguncula Brevis

The present study provides information about the diet of sympatric populations of small cetaceans in the Babitonga Bay estuary. This is the first study on the diet of these species in direct sympatry. The stomach contents of seven Guiana dolphins Sotalia guianensis and eight franciscanas Pontoporia blainvillei were analyzed. The prey of both cetaceans was mostly teleost fishes, followed by cephalopods. We identified 13 teleost fishes as part of the diet of the franciscanas, and 20 as part of the diet of Guiana dolphins. Lolliguncula brevis was the only cephalopod recorded, and was the most important prey for both cetaceans. Stellifer rastrifer and Gobionellus oceanicus were also important for franciscana, so as Mugil curema and Micropogonias furnieri were important for Guiana dolphins. Stellifer rastrifer and Cetengraulis edentulus were the fishes with the highest frequency of occurrence for franciscana (50%), while Achirus lineatus, C. edentulus, S. brasiliensis, Cynoscion leiarchus, M. furnieri, M. curema, Diapterus rhombeus, Eugerres brasilianus and G. oceanicus showed 28.6% of frequency of occurrence for Guiana dolphins. Franciscanas captured greater cephalopods than the Guiana dolphins in both total length (z= -3.38; n= 40; p< 0.05) and biomass (z = -2.46; n = 40; p<0.05). All of the prey species identified occur inside the estuary, which represents a safe habitat against predators and food availability, reinforcing the importance of the Babitonga Bay for these cetacean populations.

scholarly journals Equine enterolithiasis

2017 ◽  
Vol 59 (2) ◽  
pp. 105
Author(s):  
N. DIAKAKIS (Ν.ΔΙΑΚΑΚΗΣ)
Keyword(s):  
Clinical Signs ◽  
Intestinal Bacteria ◽  
Accurate Method ◽  
Poor Quality ◽  
Surgical Removal ◽  
Daily Consumption ◽  
Abdominal Radiography ◽  
South West ◽  
History Of ◽  
Main Components

Enterolithiasis is characterized by the presence of enteroliths in the large colon of horses with the ascending colon being the most common site of obstruction. Enteroliths are composed of ammonium magnesium phosphate, which is supplied both by the digestive processes intestinal bacteria and by feeds. The enteroliths typically form around a central nidus. Although enterolithiasis is seen all over the world, the most cases are reported from North America, and more specifically, California, South West Indiana and Florida. As far as breed is concerned, it affects predominantly Arab horses and rarely Quarter and Thoroughbreds. As far as age is concerned, it is usually seen in middle-aged horses. Although the pathogenesis of enterolithiasis is not fully understood, nutrition and heritability are believed to be a part in it. A rich diet in ammonium, magnesium and phosphorus predisposes to enterolith formation, as those elements are the main components of enteroliths. Clinical signs vary considerably and are rarely characteristic of the disease. Usually, the presence of the enterolith is free of symptoms unless it leads to obstruction. In most cases of enterolithiasis a small amount of faeces, air and the administered mineral oil could pass from the obstruction site. On the contrary, in complete obstructions the passage is closed, defecation is absent and no laxative can pass the obstruction site. The enterolith is rarely found by rectal examination. A history of recurrent colic might be connected to the presence of enteroliths that cause partial or temporary obstruction. The most accurate method for diagnosing enterolithiasis is abdominal radiography. The treatment of choice is the surgical removal of enteroliths, which has a favorable prognosis provided that the laparotomy is going to take place early in course of the disease, before the onset of peritonitis. Intestinal rupture, which rapidly leads to peritonitis, is the gravest and commonest complication. Other complications are colitis, leakage through the laparotomy site and peritonitis. In order to prevent reformation of enteroliths, the daily consumption of alfalfa hay has to be reduced dramatically and poor quality hay has to be administered.

scholarly journals Diet of St. Lawrence Estuary Beluga (Delphinapterus leucas) in a changing ecosystem

2020 ◽  
Vol 134 (1) ◽  
pp. 21-35
Author(s):  
Véronique Lesage ◽  
Stéphane Lair ◽  
Samuel Turgeon ◽  
Pierre Béland
Keyword(s):  
Prey Availability ◽  
Population Decline ◽  
Delphinapterus Leucas ◽  
Anthropogenic Factors ◽  
Adult Males ◽  
Current Time ◽  
Lawrence Estuary ◽  
The Past ◽  
Important Prey ◽  
St Lawrence Estuary

Ecosystems and community structure fluctuate over time as a result of natural and anthropogenic factors that may affect prey availability and population dynamics. Most of what we know about St. Lawrence Estuary (SLE) Beluga (Delphinapterus leucas) diet comes from stomach contents collected 80 years ago mainly from a hunting site that Beluga no longer use. How reflective these data are of Beluga diet at other sites and at the current time is unknown. In the context of the recent population decline, general information of prey species alone may help identify useful conservation actions for potentially important prey or habitats. Here, we examined the diet of SLE Beluga using digestive tracts collected from carcasses recovered over the past 30 years, in the context of historical diet data and recent changes in the St. Lawrence ecosystem. We showed they have a varied diet composed of fish and invertebrates generally <30 cm in length, and that adult males and females differ in their summer diet in a way that is consistent with the sex segregation observed in this population. Our results also indicate that polychaete worms, squid, and cod are still among the most prevalent prey, and that species such as redfish (Sebastes spp.) might be important prey items. This study shows that Beluga diet has changed since the 1930s, and that prey from digestive tracts identified to species are valuable for making comparisons to the past, and for improving applications of molecular analyses, such as stable isotopes and fatty acids.

scholarly journals Feeding Ecology of Short-Toed Snake-Eagle (Circaetus gallicus [Gmelin, 1788]) in the Montados of Iberian Peninsula

2020 ◽  
Vol 28 (2) ◽  
pp. 155-179
Author(s):  
Nuno Onofre ◽  
Luís Sampaio
Keyword(s):  
Relative Abundance ◽  
Diet Composition ◽  
Prey Species ◽  
Prey Selection ◽  
Prey Type ◽  
Generalist Predator ◽  
Important Prey ◽  
Psammodromus Algirus ◽  
Circaetus Gallicus ◽  
Water Snakes

The diet of Short-toed Snake-eagle (Circaetus gallicus) during the breeding season in an area dominated by cork and holm oak parkland forests (Montados) was analyzed in this study. As expected, results showed that snakes are the dominant prey in the diet of this eagle, comprising up to 92.5% of the identified items, if potential secondary prey species were excluded. The Montpellier Snake (Malpolon monspessulanus) was the most consumed one (42.2%), followed by the Ladder Snake (Zamenis scalaris) (28.0%), and the water snakes (Natrix spp.) (14.2%). According to the same criteria, lizards (mainly Psammodromus algirus) and mammals represent between 4.8 and 2.2%, respectively. Other animals such as pond turtle and amphibians are irregular prey (<1%), and no bird remains were found at all. Short-toed Snake-eagle is usually referred as a stenophagic predator where snakes are by far its most important prey type, and where within this taxonomic group it behaves as a generalist predator. In this study this premise was then tested comparing the relative abundance of the snake species with their proportion in the diet composition of the eagle in order to know whether or not prey selection exists with regard to the species of snakes in this region. Results point to a quite plausible "preference" for the Ladder Snake and an "avoidance" for the smooth snakes group (Macroprotodon brevis/Coronella girondica), and possibly for the Horseshoe Whip (Hemorrhois hippocrepis). The avoidance to the Horseshoe Whip must be indirect and habitat related, while in relation to the two smooth snakes it may be due in large extend to its small size, in particular.

scholarly journals Predatory Behavior of Yellow Baboons

Behaviour ◽  
1976 ◽  
Vol 56 (1-2) ◽  
pp. 44-67 ◽  
Author(s):  
Glenn Hausfater
Keyword(s):  
Prey Item ◽  
Prey Species ◽  
Predatory Behavior ◽  
Primate Species ◽  
Papio Cynocephalus ◽  
Vervet Monkeys ◽  
Adult Males ◽  
Lepus Capensis ◽  
Number Of Individuals ◽  
Prey Items

Abstract1. A group of 32 yellow baboons (Papio cynocephalus) in the Masai-Amboseli National Park, Kenya, caught and ate 45 vertebrate prey items during 2519.19 hours of observation. 2. Eighty percent of the prey items were mammals and the most frequently eaten species were African hares (Lepus capensis), vervet monkeys (Cercopithecus aethiops) and neonate gazelle (Cazella granti and G. thomsoni) in that order. The details of predatory behavior for each prey species are described. 3. Rates of predation were significantly higher during the long dry season than during other months of the year, although no correlation was found between total monthly rainfall and monthly rates of predation. A lognormal model however provided a good fit to the monthly rate of predation data suggesting that the rate of predation by Amboseli baboons was affected by several factors that acted multiplicatively with respect to each other and were themselves related to rainfall or dryness. 4. A mean of 2.3 individuals fed directly from the carcass of each prey item. A mean of 3.5 individuals per prey item fed directly or indirectly, i.e., on scraps, from each carcass. In general, both the number of individuals who fed from each carcass and the duration of their feeding bouts was dependent upon the gross body size of the prey item. Adult males fed directly from the carcass of prey items for about three times more minutes than expected from their number in the group; other classes of individuals fed directly from prey carcasses for only one-fourth as many minutes as expected. In general, an adult male would be expected to feed on each category of vertebrate prey at least once per year, while individuals of all other age-sex classes would be expected to feed on most prey categories only once every two years. 5. The most frequent social behavior around prey items was agonistic bouts; no cooperation, simultaneous feeding or specific begging gestures were observed. 6. Estimates of the total number of prey killed annually by Amboseli baboons indicate that baboon predation probably has a negligible effect on prey populations other than vervet monkeys. 7. It is speculated that the need for vitamin B12 underlies baboon predatory behavior, and perhaps that of other primate species as well.

Getting Beyond the Apemen

2021 ◽  
pp. 1-18
Author(s):  
Lesley Newson ◽  
Peter J. Richerson
Keyword(s):  
At Risk ◽  
Natural Selection ◽  
Human Evolution ◽  
Evolutionary Process ◽  
Adult Males ◽  
Evolutionary Processes ◽  
Complex Information ◽  
History Of ◽  
Evolution By Natural Selection

This introductory chapter explains why a new story of human evolution is needed, and also lays the foundations of the story told in this book. One of the reasons we need a new story is that previous stories have concentrated on what our male ancestors were doing. Since survival is most at risk in the first years of life, it makes much more sense to concentrate on children and their mothers than on adult males. A brief account of the history of ideas in evolution by natural selection and human evolution provides readers with a background in evolutionary processes. Humans are a product of evolution, but we are not like other animals, because we are connected and readily share complex information. We are unique and our evolution was the result of a unique evolutionary process. To understand ourselves in evolutionary terms, it’s necessary to consider two intertwined evolutionary processes—genes and culture.

Spatial distribution of the intertidal snail Ilyanassa obsoleta in relation to parasitism by two species of trematodes

2000 ◽  
Vol 78 (7) ◽  
pp. 1137-1143 ◽  
Author(s):  
Dean G McCurdy ◽  
J Sherman Boates ◽  
Mark R Forbes
Keyword(s):  
Spatial Distribution ◽  
Intertidal Zone ◽  
Bay Of Fundy ◽  
Spatial Distributions ◽  
Ilyanassa Obsoleta ◽  
Intermediate Hosts ◽  
Corophium Volutator ◽  
Vertical Distributions ◽  
Second Intermediate Host ◽  
Intertidal Snail

We studied the spatial distributions of mud snails (Ilyanassa obsoleta) infected by two trematodes, Lepocreadium setiferoides and Gynaecotyla adunca, on a macrotidal mudflat in the Minas Basin, Bay of Fundy. Snails, as first intermediate hosts, were castrated by both parasites, and we found no evidence of sex differences in parasitism. Similar to previous work, prevalence of L. setiferoides in I. obsoleta increased exponentially with host size (and age). Unexpectedly, prevalence of G. adunca decreased over the largest size classes of snails, a result that may be due to several causes. Distributions of both parasites across the intertidal zone differed from previous accounts in that snails infected with L. setiferoides were found only in the middle of the intertidal zone, whereas prevalence of G. adunca increased exponentially moving seaward. Several species of polychaetes could be infected by L. setiferoides in the laboratory and may act as appropriate second intermediate hosts, whereas only the amphipod Corophium volutator served as a second intermediate host for G. adunca. Finally, the vertical distributions of I. obsoleta infected by either species of trematode overlap with distributions of apparent or known second intermediate hosts.

Assessing the intrinsic resilience of a particularly fast-growing teleost prey species (red cod, Pseudophycis bachus)

2013 ◽  
Vol 64 (2) ◽  
pp. 130
Author(s):  
Jodie Kemp ◽  
Gregory P. Jenkins ◽  
Stephen E. Swearer
Keyword(s):  
Life History ◽  
Prey Species ◽  
First Year ◽  
Early Maturity ◽  
High Fecundity ◽  
Biomass Harvesting ◽  
Important Prey ◽  
Rapid Growth Rate ◽  
Poor Recruitment ◽  
Water Species

Understanding the life-history parameters that influence productivity is important in assessing the intrinsic resilience of a species to exploitation. The life-history characteristics of red cod, Pseudophycis bachus, were investigated to assess the intrinsic resilience of this important prey species to increased predation pressure by a range of high trophic-level predators. Red cod has a particularly short longevity; in Australian shelf waters it is uncommon to encounter individuals older than 2+ years. There are few shelf-water species that exhibit the rapid rate of growth that was observed where females and males attained ~300-mm total length in the first year. A particularly rapid growth rate, and a reproductive strategy characterised by early maturity and high fecundity, suggests that the species is relatively resilient. However, red cod is short lived, which exposes populations to large shifts in biomass. Harvesting of this species by predators, particularly during years of poor recruitment, may be significant in shaping the dynamics of red cod populations.

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