Two new indices for stomach content analysis of fishes

Mohan, Mahesh; Sankaran, T.

doi:10.1111/j.1095-8649.1988.tb05471.x

Cited by 58 publications

(48 citation statements)

References 2 publications

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“…Prey volume less than 5 mm 3 was estimated employing the geometric formula method. The volumetric percentage (%V), frequency of occurrence (%FO), and frequency of occurrence adjusted to 100% (%FOAJ), were calculated for each of the identified categories, according to HYSLOP (1980) and MOHAN & SANKARAN (1988). A prey was considered important, and utilized for description of the diet and foraging strategy, when presenting at least one of the indexes (%V or %FOAJ) greater than or equal to 100/S, where S is the number of prey per size class of the individuals utilized in the analysis.…”

Section: Methodsmentioning

confidence: 99%

Feeding strategy of Menticirrhus americanus and Menticirrhus littoralis (Perciformes: Sciaenidae) juveniles in a sandy beach surf zone of southern Brazil

Rodrigues¹,

Vieira²

2010

Zoologia (Curitiba, Impr.)

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The diet and foraging strategy of juvenile Menticirrhus americanus (Linnaeus, 1758) and Menticirrhus littoralis (Holbrook, 1847) were studied, testing the existence of trophic overlap between these species and within different seasons (spring and summer). Individuals were sampled using a beach seine in the surf zone near Rio Grande, state of Rio Grande do Sul, Brazil. Based on Morisita's Simplified Overlap Index and Bootstrapping technique, trophic overlap between species was considered high during the spring (Cik = 0.97 ± 0.07) and low during the summer (Cik = 0.37 ± 0.14). Juveniles shared the same food resources during the spring (FO of amphipods > 0.75), with the M. americanus diet presenting lower prey diversity (N = 7) when compared to M. littoralis (N = 13). In the summer, M. americanus presented a more varied diet (N = 13) than during the spring, suggesting a non-specialized opportunistic diet, whereas M. littoralis continued to show a diversified diet (N = 14). During the summer, M. americanus presented a generalist-opportunist feeding strategy, whereas juvenile M. littoralis tended to be more specialist

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Section: Methodsmentioning

confidence: 99%

Feeding strategy of Menticirrhus americanus and Menticirrhus littoralis (Perciformes: Sciaenidae) juveniles in a sandy beach surf zone of southern Brazil

Rodrigues¹,

Vieira²

2010

Zoologia (Curitiba, Impr.)

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“…A graphical representation of Rw index helped to elucidate the relative contribution of the occurrence or volume of every food item present in the stomach contents. The index values allow comparisons among the items following their order of importance (Mohan & Sankaran, 1988). When the value of Φ ranged from 0 to 45, the food item comprised much of the volume of the sample; in contrast, when the value of Φ ranged from 45 to 90, the food item occurred more frequently in the sample.…”

Section: φ 45| 45mentioning

confidence: 99%

“…The dietary patterns of T. borellianus were analysed using the Weighted Result Index (Rw) (Mohan & Sankaran, 1988), applying the following formula:…”

Section: Crab Collection and Gut Content Analysismentioning

confidence: 99%

Feeding ecology of the freshwater crab Trichodactylus borellianus (Decapoda: Trichodactylidae) in the floodplain of the Parana River, southern South America

Williner¹,

Collins²

2013

lajar

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ABSTRACT. Freshwater crabs are not commonly considered to be an important group in trophic webs, and this might be due to a lack of knowledge about their trophic roles in aquatic ecosystems. Trichodactylus borellianus is one of the most common and widely distributed freshwater crabs in the floodplains of the southern South American rivers. The main objective of the present study was to examine the trophic role of T. borellianus, in the floodplain of the Paraná River, and its relationships with the freshwater littoral community. The trophic spectrum of this species was characterized for both sexes and individuals of different sizes (adults and juveniles), throughout daily and seasonal cycles. Samples were collected from the aquatic vegetation of three shallow lakes. The diet composition and the feeding activity of T. borellianus were evaluated through the examination of the stomach contents and their degree of emptiness. This crab species consumed several plant and animal items, including amoebas, rotifers, oligochaetes, copepods, cladocerans, and insect larvae. Moreover, this species consumes filamentous and unicellular algae, diatoms, fungi, and macrophytic remains. The predatory habits varied with the season and time of day, and variations in the feeding activity of the juveniles and adults were detected and documented. The diversity of food items eaten by this crab suggests that its trophic role in the community as an omnivore and opportunistic predator provides a connection among several trophic levels from both aquatic and terrestrial communities. Keywords: omnivore, trophic habits, stomach contents, detritus, macro-invertebrates. Ecología trófica del cangrejo dulceacuícola Trichodactylus borellianus (Decapoda:Trichodactylidae) en el valle de inundación del río Paraná, sur de Sudamérica RESUMEN. Los cangrejos de agua dulce no son comúnmente considerados como un grupo importante en las redes tróficas, y esto podría ser debido a falta de conocimiento acerca de sus funciones tróficas en los ecosistemas acuáticos. Trichodactylus borellianus es uno de los cangrejos de agua dulce más comunes y ampliamente distribuido en llanuras de inundación del los ríos del sur de Sudamérica. El objetivo principal del presente estudio fue examinar el rol trófico de T. borellianus en la llanura de inundación del río de Paraná, y sus relaciones con la comunidad litoral de agua dulce. El espectro trófico de esta especie se caracterizó en ambos sexos e individuos de diferentes tamaños (adultos y juveniles), a través de los ciclos diarios y estacionales. Se tomaron muestras en la vegetación acuática de tres lagunas diferentes. La composición de la dieta y la actividad de alimentación de T. borellianus fueron evaluados mediante la observación de contenidos estomacales y grado de repleción. Esta especie consume plantas y animales, incluyendo amebas, rotíferos, oligoquetos, copépodos, cladóceros y larvas de insectos. Además, consume algas filamentosas y unicelulares, diatomeas, hongos y restos de macrófitas. Los hábitos de consumo vari...

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“…Frequency of Occurrence (%FO) and wet weight percentage (%W) were combined to calculate the Preponderance Index (%IP) (Mohan & Sankaran, 1988). Additionally, diet data were grouped into two seasonal groups: summer-autumn (January to June), and winter-spring (July to December) (Paredes, 2015), toward establishing the order of numerical dominance of items within the diet, according to the following:…”

Section: Diet Studymentioning

confidence: 99%

Feeding ecology of the green turtle Chelonia mydas in northern Peru

Jiménez

Pingo

Alfaro‐Shigueto

et al. 2017

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ABSTRACT. Diet and food preferences of the green turtle Chelonia mydas were analyzed based on digestive tract contents of dead specimens caught incidentally by an artisanal gillnet fishery in Sechura Bay, northern Peru. We examined 27 digestive tracts and identified 35 prey items. The sampled turtles were all juveniles (CCL = 53.7 ± 1.2 cm, range 40.5-67.0 cm). The prey items were grouped into six categories: algae, cnidarians, mollusks, arthropods, chordates and garbage/anthropogenic debris. The items with the highest Frequency of Occurrence values (% FO) were: Caulerpa filiformis (77.8%), Loligo gahi (eggs) (51.9%) and Rhodymenia corallina (44.4%). By weight (% W), the most important items, were L. gahi (eggs) (33.3%), Stomolophus sp. (7.3%) and Aphos porosus (6.5%). According to the Preponderance Index (%IP), the preponderant item was L. gahi (eggs) with 6.1% and 61.2% during winter-spring and summer-autumn, respectively. According to the Resultant Weight index (Rw) of wet items, the most important items were: C. filiformis (13.1%), L. gahi (eggs) (10.5%), R. corallina (7.4%), plastic (7.5%), Gigartina chamissoi (5.1%). Garbage/anthropogenic debris was common in the digestive tracts analyzed. Plastic items had a frequency of occurrence of 44.4%. A greater diversity of food items was observed during summer and autumn. This study shows that juvenile C. mydas forage on a variety of resources. We recommend that conservation plans, land use planning and future management plans in the Sechura Bay include green turtles as a sentinel species for monitoring biodiversity of marine resources and the degree of pollution in the Bay.

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Two new indices for stomach content analysis of fishes

Cited by 58 publications

References 2 publications

Feeding strategy of Menticirrhus americanus and Menticirrhus littoralis (Perciformes: Sciaenidae) juveniles in a sandy beach surf zone of southern Brazil

Feeding strategy of Menticirrhus americanus and Menticirrhus littoralis (Perciformes: Sciaenidae) juveniles in a sandy beach surf zone of southern Brazil

Feeding ecology of the freshwater crab Trichodactylus borellianus (Decapoda: Trichodactylidae) in the floodplain of the Parana River, southern South America

Feeding ecology of the green turtle Chelonia mydas in northern Peru

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