نتایج جستجو برای: himantura walga
تعداد نتایج: 103 فیلتر نتایج به سال:
Gillnets are a widely used fishing gear in Kenya’s artisanal fisheries, yet their mesh sizes inadequately monitored or regulated. This study evaluated the impacts of gillnets seven stretched-mesh sizes, through comparative analysis species-related metrics and catch per unit effort (CPUE), to inform small-scale fisheries regulations. Data were collected from June 2014 May 2015. Three mesh-size g...
Stingrays are an important part of the biomass of the fishes in shallow coastal ecosystems, particularly in inter-reefal areas. In these habitats, they are considered keystone species – modifying physical and biological habitats through their foraging and predation. Here, we quantify the effects of bioturbation by rays on sand flats of Ningaloo Reef lagoon in Western Australia. We measured the ...
Habitat selection decisions by consumers has the potential to shape ecosystems. Understanding the factors that influence habitat selection is therefore critical to understanding ecosystem function. This is especially true of mesoconsumers because they provide the link between upper and lower tropic levels. We examined the factors influencing microhabitat selection of marine mesoconsumers - juve...
Six species of Acanthobothrium, 4 described as new, are reported in stingrays from southern Ecuador. Acanthobothrium atahualpai n. sp. in Gymnura afuerae most closely resembles Acanthobothrium fogeli and Acanthobothrium parviuncinatum by having bothridial hooks with recurved prongs and short handles. It differs from A. fogeli by having bothridial hooks 163-195 microns vs. 78-114 microns long an...
We compared levels of the major organic osmolytes in the muscle of elasmobranchs, including the methylamines trimethylamine oxide (TMAO), betaine and sarcosine as well as the beta-amino acids taurine and beta-alanine, and the activities of enzymes of methylamine synthesis (betaine and TMAO) in species with a wide range of urea contents. Four marine, a euryhaline in freshwater (Dasyatis sabina),...
تحقیق حاضر در زمستان 1387، به منظور مقایسه و تعیین غلظت فلزات سنگین آهن، جیوه، روی و مس در بافت عضله گونه کفزی سپر ماهی چهار گوش (himantura gerrardi) و گونه پلاژیک گیش چشم درشت (selar crumenophthalmus) خلیج فارس صورت گرفت. آبهای هرمزگان در محدوده ''30 º 54 تا ''30 56º شرقی و 26 تا 27 درجه شمالی (عمق 10 تا 50 متری) بعنوان منطقه مورد مطالعه در نظر گرفته شد. بافت عضله 51 نمونه ...
مطالعه حاضر با اهداف بررسی رژیم غذایی سه گونه سفره ماهی از خانواده Dasyatidae شامل گونههای Himantura imbricata، H. randalli و Pastinachus sephen در محدوده آبهای ایرانی خلیج عمان و تنگه هرمز، روابط غذایی بین آنها و تخمین سطح تغذیهای برای هر گونه انجام شد. در مجموع 191 معده متعلق به سه گونه جمعآوری شد و با شاخصهای VI، %FO، %IRI، سطح غذایی و شاخص P...
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