Quantitative methods for the determination of abundance of mobile prey of ghost crabs, Ocypode Weber, 1795 (Decapoda: Brachyura: Ocypodidae), a top predator on sandy shores

2019 ◽  
Vol 39 (4) ◽  
pp. 516-521
Author(s):  
Adeline Y P Yong ◽  
Shirley S L Lim
Keyword(s):  
Quantitative Methods ◽  
Sandy Beaches ◽  
Food Resources ◽  
Activity Period ◽  
Tropical Regions ◽  
Top Predators ◽  
Ghost Crabs ◽  
Prey Interaction ◽  
Feeding Activities ◽  
Prey Items

ABSTRACT Ghost crabs, OcypodeWeber, 1795 (Decapoda: Brachyura: Ocypodidae) are the top-benthic predators on sandy beaches in the sub-tropical and tropical regions around the world. They are omnivores and opportunistic feeders with varied feeding modes, such that they can exert cascading trophic effects on intertidal communities. Although there is a wealth of literature on the diet of ghost crabs based on qualitative reports of direct observation of predation, tracks/signs of feeding activities, or presence/absence data of prey items in foregut content analyses, there is hardly any quantitative analyses of food resources in the field that are available to these top predators on the sandy shore. While the abundance of immobile food resources can be ascertained by sediment sample assays, specialized sampling methods have been used for the collection and enumeration of mobile prey items. There is a need also to understand the period of foraging activity of the study species in order to track the predator-prey interaction at the appropriate time of the day. We outline three techniques suitable for the collection of prey types with different distribution, activity period and mobility: 1) surface-dwelling prey, 2) prey that burrow, and 3) prey that are capable of flying, a novel method that has not been utilized and described before.

Changes in the behaviour ofOcypode quadrata(Fabricius, 1787) after experimental trampling

2018 ◽  
Vol 99 (5) ◽  
pp. 1135-1140 ◽  
Author(s):  
Leonardo Lopes Costa ◽  
Julyana Figueiredo Madureira ◽  
Ilana Rosental Zalmon
Keyword(s):  
Surface Activity ◽  
Sampling Design ◽  
Lower Surface ◽  
Sandy Beaches ◽  
Controlled Experiment ◽  
Visitation Rates ◽  
Ghost Crabs ◽  
Before And After

AbstractThe effects of trampling are usually confounded by the diffuse impacts of the urbanization of sandy beaches. We performed a controlled experiment on a beach with low visitation rates to test the hypothesis that ghost crabs avoid building their burrows on impacted plots as a result of the compacted sediment, and they migrate to non-trampled areas. The sampling design encompassed 11 survey quadrats (6 × 6 m) above the strandline, including five trampled plots (100, 300, 900, 1500 and 3000 steps) and six non-trampled plots. The plots were sampled before and after 24, 48 and 72 h of experimental trampling. We found that the ghost crabs avoided building their burrows in only the 1500× and 3000× trampled plots after 24 h, but the avoidance was not related to sediment compactness. Additionally, the emersion time and escape distance from humans were significantly delayed in the most trampled plots, suggesting a lower surface activity and an avoidance of irregular (i.e. high micro-relief) sediment surfaces by ghost crabs, which might reduce their ability to perceive potential predators.

Seasonal variation in the diet of a population of Hyla arborea from Romania

2007 ◽  
Vol 28 (4) ◽  
pp. 485-491 ◽  
Author(s):  
Diana Cupsa ◽  
Tibor Hartel ◽  
Severus-Daniel Covaciu-Marcov ◽  
István Sas ◽  
Éva-Hajnalka Kovács ◽  
...  
Keyword(s):  
Dietary Diversity ◽  
Diversity Index ◽  
Stomach Contents ◽  
Activity Period ◽  
Feeding Intensity ◽  
Terrestrial Environment ◽  
Hyla Arborea ◽  
Plant Remains ◽  
Almost All ◽  
Prey Items

Abstract We examined the diet of Hyla arborea over its entire activity period (March to late September, 2004), and analysed a total of 585 adult samples. From the stomach contents we identified plant remains, shed-skin fragments, and animals. We identified a total of 2976 prey items, almost all of which originated from the terrestrial environment. Adult araneans and coleopterans were the most abundant prey items in the diet of the studied tree frogs. Some of the prey items become abundant in certain parts of the year (e.g. Homoptera, Lepidoptera larvae, Trichoptera). The dietary diversity index is high and exhibits seasonal changes. During the period of study an important seasonal change was observed in feeding intensity and in the type of consumed prey. Our results show that Hyla arborea has a broad dietary diversity which was expected as a consequence of exploiting the habitat both vertically and horizontally, possibly allowing access to a broader spectrum of prey.

scholarly journals The bottlenose dolphin Tursiops truncatus foraging around a fish farm: Effects of prey abundance on dolphins’ behavior

2009 ◽  
Vol 55 (4) ◽  
pp. 243-248 ◽  
Author(s):  
Bruno Díaz López
Keyword(s):  
Group Size ◽  
Human Activities ◽  
Bottlenose Dolphin ◽  
Bottlenose Dolphins ◽  
Dive Duration ◽  
Fish Farm ◽  
Prey Abundance ◽  
Diving Behavior ◽  
Top Predators ◽  
Feeding Activities

Abstract The extent to which prey abundance influences both bottlenose dolphin foraging behavior and group size in the presence of human activities has not previously been studied. The primary aim of this study was to identify and quantify how wild bottlenose dolphins respond, individually and as groups, to the relative abundance of prey around a fish farm. Detailed views of dolphins’ behavior were obtained by focal following individual animals whilst simultaneously collecting surface and underwater behavioral data. A total of 2150 dive intervals were analyzed, corresponding to 342 focal samples, lasting over 34 hours. Bottlenose dolphins remained submerged for a mean duration of 46.4 seconds and a maximum of 249 seconds. This study provides the first quantified data on bottlenose dolphin diving behavior in a marine fin-fish farm area. This study’s results indicate that within a fish farm area used intensively by bottlenose dolphins for feeding, dolphins did not modify dive duration. Additionally, underwater observations confirmed that dolphins find it easier to exploit a concentrated food source and it appears that hunting tactic and not group size plays an important role during feeding activities. Thus, bottlenose dolphins appear capable of modifying their hunting tactics according to the abundance of prey. When top predators display behavioral responses to activities not directed at them, the task of studying all possible effects of human activities can become even more challenging.

Feeding of the least, crested, and parakeet auklets around St. Lawrence Island, Alaska

1969 ◽  
Vol 47 (5) ◽  
pp. 1025-1050 ◽  
Author(s):  
Jean Bédard
Keyword(s):  
Breeding Season ◽  
Feeding Habits ◽  
Food Resources ◽  
Early Summer ◽  
Depth Range ◽  
Relative Importance ◽  
Feeding Apparatus ◽  
Structural Differences ◽  
Aethia Cristatella ◽  
Prey Items

The feeding habits of three plankton-feeding Alcidae, the least, crested, and parakeet auklets were studied on St. Lawrence Island, Alaska, between 1964 and 1966. The crested and the least auklets (Aethia cristatella, A. pusilla) exhibit similar patterns of dependence upon the food resources: both have, during early summer, a diversified diet consisting of mysids, hyperiids, gammarids, etc., but restrict themselves largely to one principal prey during the chick-rearing period. Then, A. pusilla eats mostly Calanus sp. while A. cristatella eats Thysanoessa spp. In all years, hatching coincided closely with the appearance of these prey items (copepods and euphausids) in the environment and it is argued that the timing of the auklets' breeding season has been adjusted to their cyclical abundance. Cyclorrhynchus psittacula, the parakeet auklet, maintains a diversified diet throughout the summer: Parathemisto libellula, a pelagic amphipod, is the dominant prey in its diet.The three species are found feeding together and are presumed to use the same depth range. Segregation in feeding between A. cristatella and A. pusilla is achieved by difference in bill size. This difference is sufficient to impose obligatory feeding upon different resources. Segregation between two possible competitors, A. cristatella and Cyclorrhynchus, seems to rest upon innate preferences for different prey types, minor structural differences in the feeding apparatus, and differences in foraging habits: the relative importance of each of these factors remains to be established.As a whole, the amount of overlap in feeding between the three species studied is very small.

Compression of home ranges in ghost crabs on sandy beaches impacted by vehicle traffic

2010 ◽  
Vol 157 (11) ◽  
pp. 2467-2474 ◽  
Author(s):  
Thomas A. Schlacher ◽  
Serena Lucrezi
Keyword(s):  
Sandy Beaches ◽  
Home Ranges ◽  
Vehicle Traffic ◽  
Ghost Crabs

scholarly journals Formación del banco de semillas durante la revegetación temprana de áreas afectadas por la minería en un bosque pluvial tropical del Chocó, Colombia

2016 ◽  
Vol 65 (1) ◽  
pp. 393
Author(s):  
Hamleth Valois-Cuesta ◽  
Carolina Martínez-Ruiz ◽  
Yorley Urrutia-Rivas
Keyword(s):  
Seed Bank ◽  
Soil Seed Bank ◽  
Forest Edge ◽  
Seed Rain ◽  
Abandoned Mines ◽  
Activity Period ◽  
Tropical Regions ◽  
High Rainfall ◽  
Management Actions ◽  
Disturbed Areas

Mining is one of the main economic activities in many tropical regions and is the cause of devastation of large areas of natural tropical forests. The knowledge of the regenerative potential of mining disturbed areas provides valuable information for their ecological restoration. The aim of this study was to evaluate the effect of age of abandonment of mines and their distance from the adjacent forest, on the formation of soil seed bank in abandoned mines in the San Juan, Chocó, Colombia. To do this, we determined the abundance and species composition of the soil seed bank, and the dynamics of seed rain in mines of different cessation period of mining activity (6 and 15 years), and at different distances from the adjacent forest matrix (50 and 100 m). Seed rain was composed by five species of plants with anemocorous dispersion, and was more abundant in the mine of 6 years than in the mine of 15 years. There were no significant differences in the number of seeds collected at 50 m and 100 m from the adjacent forest. The soil seed bank was represented by eight species: two with anemocorous dispersion (common among the seed rain species) and the rest with zoochorous dispersion. The abundance of seeds in the soil did not vary with the age of the mine, but was higher at close distances to the forest edge than far away. During the early revegetation, the formation of the soil seed bank in the mines seems to be related to their proximity to other disturbed areas, rather than their proximity to the adjacent forest or the cessation activity period of mines. Therefore, the establishment of artificial perches or the maintenance of isolated trees in the abandoned mines could favour the arrival of bird-dispersed seeds at mines. However, since the soil seed bank can be significantly affected by the high rainfall in the study area, more studies are needed to evaluate management actions to encourage soil seed bank formation in mines of high-rainfall environments in the Chocó region.

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