نتایج جستجو برای: copepods
تعداد نتایج: 2457 فیلتر نتایج به سال:
In recent decades temperature elevation has been the focus of many studies on climate change, including effects on planktonic communities, but few studies have examined the effects of increased water color ("brownification"). Since these changes are likely to occur simultaneously, it is important to investigate their potential interactive effects. Accordingly, we performed a mesocosm experiment...
Our long-range objectives are to understand and, as feasible, predict the distribution and abundance of pelagic organisms, particularly in regard to their physical environment and its changes. The objective of the proposed research is to identify the mechanism that controls onset of dormancy in open-ocean copepods and thus explain spatial and temporal variation in dormancy response. Specificall...
Knowledge of in situ copepod diet diversity is crucial for accurately describing pelagic food web structure but is challenging to achieve due to lack of an easily applicable methodology. To enable analysis with whole copepod-derived DNAs, we developed a copepod-excluding 18S rDNA-based PCR protocol. Although it is effective in depressing amplification of copepod 18S rDNA, its applicability to d...
a r t i c l e i n f o Interactions between zooplankton not only affect the world's carbon fixation but also have a direct impact on the yields of the fishing industry. Both copepods and ciliates have a crucial linkage role in constituting the marine food web. Analyzing the predator–prey interactions between these two species helps us to understand the productivity of oceans better. In this stud...
Copepod growth rates were estimated from shipboard measurements of egg production of adult female Calanus agulhensis, Calanoides carinatus, Nannocalanus minor, and Centropages brachiatus and molting rates of juvenile stages (N6–C5) of C. agulhensis. Data were obtained during austral spring and summer of 1989–1995 in the southern Benguela upwelling system. While maximum growth rates showed less ...
It is well established that small-sized live feed with sufficient DHA, EPA and ARA as starter feed is the key factor for the success in larviculture of marine fishes with altricial larvae having limited yolk, which are in an undeveloped state at hatching. Copepods form a major component of the natural diet of many fish larvae and the wide range of body sizes of copepods both within and between ...
The estuarine planktonic copepods have a wide geographical distribution and commendable tolerance to various kinds of contaminants. The primary aim of the present study was to contrast the impacts of model POPs (TBBPA and HBCD) on three common estuarine planktonic copepods (Oithona similis, Acartia pacifica and Pseudodiaptomus inopinus) and establish a protocol for the assessment of acute toxic...
Copepods are important grazers on microplankton in marine food webs and are, in turn, preyed upon by a wide range of predators with diverse feeding adaptations. Although copepods have evolved numerous adaptations to help them avoid predation, their escape behavior sets them apart from many other planktonic organisms. Mechanoreception is widely used by copepods to detect hydrodynamic disturbance...
This article provides an overview of research on chromatin diminution (CD) in copepods. The phenomenology, mechanisms and biological role of CD are discussed. A model of CD as an alternative means of regulating cell differentiation is presented. While the vast majority of eukaryotes inactivate genes that are no longer needed in development by heterochromatinization, copepods probably use CD for...
We analyzed the effects of UV radiation (UVR) effects on acetylcholinesterase (AChE) activity in two calanoid copepods, Boeckella gibbosa and Parabroteas sarsi that inhabit Patagonian shallow lakes. We studied the effect of experimental UVR (UV-B and UV-A) exposure on AChE activity in relation to basal antioxidant capacities of both copepods. Our experiments showed that UVR can effectively depr...
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