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1.
Sci Total Environ ; 703: 135655, 2020 Feb 10.
Artículo en Inglés | MEDLINE | ID: mdl-31767324

RESUMEN

Marine copepods play an important role in transferring mercury to higher trophic levels in aquatic ecosystems. Exposure time is an important environmental parameter that potentially influences the bioaccumulation and biomagnification of Hg in copepods, which increases the uncertainty in risk assessments of Hg in food chains. In the present study, we employed the radiotracer technique to evaluate the efflux behavior of inorganic mercury [Hg(II)] and methylmercury (MeHg), and the effects of exposure time in a population of Tigriopus japonicus copepods. Exposure treatments were compared to understand the effects of exposure time (1 d, 3 d, and 7 d) on the release routes and efflux rate constants (ke) of Hg in copepods. During a depuration period of 5 d, the ke value of Hg(II) in the three exposure treatments ranged from 0.190-0.330 d-1, while the ke of MeHg was generally slower and ranged from 0.031-0.051 d-1. The exposure time significantly affected the efflux rates of Hg(II), i.e., a longer exposure time caused a higher retained Hg(II) burden in copepods, while no significant changes were observed in the MeHg treatments. The release routes of Hg in T. japonicus included excretion, feces production, and reproduction. In all the treatments, the excretion of Hg was the most important release route. The relative contribution of reproduction significantly increased in the MeHg exposure treatments, while the contribution of water excretion decreased with exposure time. Our study demonstrated that the retention of Hg(II) and the maternal transfer of MeHg were time-dependent and significantly affected by exposure time. Long-term exposure caused a decrease in the ke of Hg(II) and increase in the contribution of MeHg transfer to nauplii, thereby indicating an increasing risk of biological transmission of Hg under long-term exposure.


Asunto(s)
Copépodos/fisiología , Mercurio/metabolismo , Compuestos de Metilmercurio/metabolismo , Contaminantes Químicos del Agua/metabolismo , Animales , Fenómenos Bioquímicos , Transporte Biológico , Ecosistema , Cadena Alimentaria , Cinética , Contaminantes Químicos del Agua/análisis
2.
Syst Parasitol ; 96(8): 715-722, 2019 11.
Artículo en Inglés | MEDLINE | ID: mdl-31515681

RESUMEN

A new species of Dermoergasilus Ho & Do, 1982 (Copepoda: Ergasilidae) parasitic on the gills of the redbelly tilapia Coptodon zillii (Gervais) from Basrah, southern Iraq, is described. Dermoergasilus cichlidus n. sp. is morphologically similar to D. longiabdominalis El-Rashidy & Boxshall, 2001 in the body length to width ratio, the swimming legs armature, the shape of the urosome and the small slightly spiniform seta on the exopodal segment of leg 5. However, the main differences are the presence of long setae on the endopod of leg 1 in D. cichlidus n. sp. (vs relatively short setae); the inner apical spine on the tip of the endopod of leg 1 being only slightly longer than the outer apical spine (vs inner apical spine about twice as long as the outer); the first interpodal sternite ornamented with spinules (vs interpodal sternites not ornamented); and the caudal rami and anal somite of equal length (vs caudal rami length c.2/3 of the length of the anal somite). Dermoergasilus occidentalis can be distinguished from D. cichlidus n. sp. by the relative length of the antennal segments, the absence of a minute terminal spine on the digital process of the caudal ramus and by differences in the mouth parts.


Asunto(s)
Copépodos/clasificación , Copépodos/fisiología , Tilapia/parasitología , Animales , Copépodos/anatomía & histología , Branquias/parasitología , Irak , Especificidad de la Especie
3.
J Fish Dis ; 42(11): 1573-1586, 2019 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-31506962

RESUMEN

The aims of the present study were to describe the salmon lice (Lepeophtheirus salmonis Krøyer, 1837) situation in an intensive salmon production area in mid-Norway and to consider implications of changing practices of how salmon lice infestation can be controlled. The results in this study suggest that there are steps that can be carried out to keep salmon lice under control even during years when the temperature facilitates a quick salmon lice development. The present work indicates that the use of cleaner fish can delay the time it takes adult female lice to reach 0.1 per salmon in the beginning of a production cycle. It suggests that the timing of cleaner fish deployment into salmon cages can influence its effectiveness in controlling salmon lice. It also gives caution to letting salmon lice develop unchecked, even at levels far below the current lice limit, because of the difficulties to control salmon lice when the external infection pressure is too high. This study took place during a rapid change in delousing methods, in an area with coordinated salmon production. Despite its exploratory nature, this study offers insights into the salmon lice fluctuations in relation to efforts aimed at controlling it.


Asunto(s)
Acuicultura/métodos , Copépodos/fisiología , Infestaciones Ectoparasitarias/veterinaria , Enfermedades de los Peces/prevención & control , Salmo salar , Animales , Infestaciones Ectoparasitarias/parasitología , Infestaciones Ectoparasitarias/prevención & control , Enfermedades de los Peces/parasitología , Noruega
4.
Sci Total Environ ; 687: 780-789, 2019 Oct 15.
Artículo en Inglés | MEDLINE | ID: mdl-31412481

RESUMEN

Microplastics (1 µm-5 mm) are a ubiquitous marine contaminant of global concern, ingested by a wide range of marine taxa. Copepods are a key component of marine food webs, providing a source of food for higher trophic levels, and playing an important role in marine nutrient cycling. Microplastic ingestion has been documented in copepods, but knowledge gaps remain over how this affects feeding preference and faecal density. Here, we use exposure studies incorporating algal prey and microplastics of varying sizes and shapes at a concentration of 100 microplastics mL-1 to show: (1) prey selection by the copepod Calanus helgolandicus was affected by the size and shape of microplastics and algae they were exposed to; Exposure to nylon fibres resulted in a 6% decrease in ingestion of similar shaped chain-forming algae, whilst exposure to nylon fragments led to an 8% decrease in ingestion of a unicellular algae that were similar in shape and size. (2) Ingestion of microplastics with different densities altered the sinking rates of faecal pellets. Faeces containing low-density polyethylene sank significantly more slowly than controls, whilst sinking rates increased when faeces contained high-density polyethylene terephthalate. These results suggest that C. helgolandicus avoid ingesting algae that are similar in size and/or shape to the microplastic particles they are exposed to, potentially in a bid to avoid consuming the plastic.


Asunto(s)
Copépodos/fisiología , Monitoreo del Ambiente , Plásticos/toxicidad , Contaminantes Químicos del Agua/toxicidad , Animales , Heces , Cadena Alimentaria , Zooplancton
5.
Syst Parasitol ; 96(7): 603-616, 2019 09.
Artículo en Inglés | MEDLINE | ID: mdl-31372880

RESUMEN

Lepeophtheirus lichiae Barnard, 1948 (Copepoda: Caligidae), a very rare and poorly known sea louse, is redescribed based on a single newly collected female. The specimen was collected from the dorsal body surface of the leerfish, Lichia amia (Linnaeus) caught in north-eastern Mediterranean waters off the Turkish coast. The original and only available description of L. lichiae was incomplete and with only three illustrations: the dorsal view of the female habitus, the sternal furca, and the postantennal process. Here, we present a full re-description of female of L. lichiae and report it from the Mediterranean Sea for the first time.


Asunto(s)
Copépodos/clasificación , Copépodos/fisiología , Perciformes/parasitología , Animales , Copépodos/citología , Femenino , Mar Mediterráneo , Especificidad de la Especie
6.
Mar Pollut Bull ; 142: 433-451, 2019 May.
Artículo en Inglés | MEDLINE | ID: mdl-31232322

RESUMEN

Mesozooplankton was sampled seasonally in a large microtidal estuary (Peel-Harvey) suffering from massive macroalgal growths and cyanobacterial blooms. Comparisons with other estuaries indicate that eutrophication led to copepod abundance declining and macroalgal-associated species increasing. Mesozooplankton species are almost exclusively autochthonous, i.e. spend entire life cycle within the estuary. Meroplanktonic species are virtually absent because main benthic macroinvertebrate species undergo direct benthic rather than planktotrophic development. There are also few abundant holoplanktonic species. Most species are tychoplanktonic, i.e. benthic and transported into plankton through physical disturbance of sediment. Species number, concentration and Simpson's Index are greater during night than day. Annual cyclical changes in species composition are related closely to changes in salinity. At the most degraded site, nematode concentrations were high and the species number and concentration changed markedly during extreme eutrophication, when oxygen concentrations were low, disrupting annual cyclical changes in species composition.


Asunto(s)
Copépodos/fisiología , Estuarios , Eutrofización , Zooplancton/fisiología , Animales , Australia , Cianobacterias/fisiología , Monitoreo del Ambiente , Densidad de Población , Salinidad , Estaciones del Año
7.
Aquat Toxicol ; 213: 105213, 2019 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-31200332

RESUMEN

Atrazine is a widely used pesticide which acts as an endocrine disruptor in various organisms. The aim of this study was to investigate adverse effects of atrazine on life parameters, oxidative stress, and ecdysteroid biosynthetic pathway in the marine copepod Tigriopus japonicus. In T. japonicus, no mortality was shown in response to atrazine up to 20 mg/L in acute toxicity assessment. In nauplii, retardation in the growth and prolonged molting and metamorphosis resulted under chronic exposure of atrazine at 20 mg/L. In addition, body sizes of T. japonicus nauplii were significantly decreased (P < 0.01 in length and P < 0.001 in width) in response to 20 mg/L of atrazine. Furthermore, atrazine induced oxidative stress by the generation of reactive oxygen species at all concentrations compared to the control in the nauplii. Also, significant increase in glutathione-S transferase activity was observed in adult T. japonicus at low concentration of atrazine. To understand effects of atrazine on ecdysteroid biosynthetic pathway-involved genes (e.g., neverland, CYP307E1, CYP306A1, CYP302A1, CYP3022A1 [CYP315A1], CYP314A1, and CYP18D1) were examined with mRNA expressions of ecdysone receptor (EcR) and ultraspiracle (USP) in response to 20 mg/L atrazine in nauplii and adults. In the nauplii, these genes were significantly downregulated (P < 0.05) in response to atrazine, compared to the control but not in the adult T. japonicus. These results suggest that atrazine can interfere in vivo life parameters by oxidative stress-induced retrogression and ecdysteroid biosynthetic pathway in this species.


Asunto(s)
Organismos Acuáticos/metabolismo , Atrazina/toxicidad , Vías Biosintéticas/efectos de los fármacos , Copépodos/efectos de los fármacos , Ecdisteroides/biosíntesis , Estrés Oxidativo/efectos de los fármacos , Animales , Organismos Acuáticos/efectos de los fármacos , Organismos Acuáticos/genética , Atrazina/química , Vías Biosintéticas/genética , Tamaño Corporal/efectos de los fármacos , Copépodos/genética , Copépodos/fisiología , Regulación de la Expresión Génica/efectos de los fármacos , Glutatión Transferasa/metabolismo , Estrés Oxidativo/genética , ARN Mensajero/genética , ARN Mensajero/metabolismo , Especies Reactivas de Oxígeno/metabolismo , Contaminantes Químicos del Agua/toxicidad
8.
PLoS One ; 14(5): e0217047, 2019.
Artículo en Inglés | MEDLINE | ID: mdl-31107897

RESUMEN

Phytoplankton are the oceans' principal source of polyunsaturated fatty acids that support the growth and reproduction of consumers such as copepods. Previous studies have demonstrated ocean acidification (OA) can change the availability of polyunsaturated fatty acids to consumer diets which may affect consumer reproduction. Two laboratory experiments were conducted to examine the effects of feeding high-pCO2-reared phytoplankton on copepod egg production, hatching success, and naupliar survival. Marine phytoplankton Rhodomonas salina, Skeletonema marinoi, Prorocentrum micans, and Isochrysis galbana were exponentially grown in semi-continuous cultures at present (control) (400 ppm CO2, pH~8.1) and future (1,000 ppm CO2, pH~7.8) conditions and provided to Acartia tonsa copepods over 4 consecutive days as either nitrogen-limited (Exp. I) or nitrogen-depleted (Exp. II) mixed assemblage of phytoplankton. The composition of FAs in the phytoplankton diet was affected by pCO2 concentration and nitrogen deficiency; the ratio of essential fatty acids to total polyunsaturated fatty acids decreased in phytoplankton grown under high pCO2 and the mass of total fatty acids increased under nitrogen depletion. Additionally, total concentrations of essential fatty acids and polyunsaturated fatty acids in the diet mixtures were less under the high-pCO2 compared to the control-pCO2 treatments. Median egg production, hatching success, and naupliar survival were 48-52%, 4-87%, and 9-100% lower, respectively, in females fed high-pCO2 than females fed low-pCO2 phytoplankton, but this decrease in reproductive success was less severe when fed N-depleted, but fatty acid-rich cells. This study demonstrates that the effects of OA on the nutritional quality of phytoplankton (i.e., their cellular fatty acid composition and quota) were modified by the level of nitrogen deficiency and the resulting negative reproductive response of marine primary consumers.


Asunto(s)
Copépodos/fisiología , Océanos y Mares , Fitoplancton/fisiología , Agua de Mar/química , Alimentación Animal , Animales , Dióxido de Carbono/química , Diatomeas/fisiología , Ácidos Grasos Insaturados/química , Femenino , Concentración de Iones de Hidrógeno , Masculino , Nitrógeno/química , Valor Nutritivo , Reproducción
9.
Aquat Toxicol ; 212: 186-193, 2019 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-31129414

RESUMEN

Ocean acidification (OA) is caused by alteration of global ocean carbon chemistry due to the increased pCO2 in the atmosphere and caused deleterious impacts on the marine ecosystem. Although various detrimental effects of OA were reported in marine organisms, the potential impact of OA on aquatic invertebrates still remains largely unknown. Here, we examined changes in life parameters and antioxidant system in response to low pH (7.5 and 7) in the marine copepod Tigriopus japonicus. Exposures to lower pHs (pH 7.5 and 7.0) of copepods resulted in lengthening of the developmental time with decreased fecundity and body length. Also, they showed increased reactive oxygen species contents with enhanced glutathione S-transferase and glutathione reductase activities but decreased glutathione peroxidase and superoxide dismutase activities in pH-dependent manner, indicating that OA exposure caused disturbance of the redox system in T. japonicus. Among several oxidative stress-related genes, GSTs2b was significantly up-regulated in response to OA. These findings will be helpful for a better understanding on the potential impact of OA on life parameters and antioxidant system in the marine copepod T. japonicus.


Asunto(s)
Copépodos/fisiología , Estrés Oxidativo/fisiología , Oxidorreductasas/metabolismo , Agua de Mar/química , Animales , Tamaño Corporal/fisiología , Carbono/química , Fertilidad/fisiología , Concentración de Iones de Hidrógeno , Océanos y Mares , Oxidación-Reducción , Especies Reactivas de Oxígeno
10.
PLoS One ; 14(5): e0216140, 2019.
Artículo en Inglés | MEDLINE | ID: mdl-31136574

RESUMEN

Many countries are in search of more effective and sustainable methods for controlling dengue vectors, due to undeniable inefficiencies in chemical and mechanical vector control methods. Bio-control of vectors by copepods is an ideal method of using interactions in the natural ecosystem for vector management, with minimum consequences on the environment. Current study determined the predatory efficacy of five locally abundant copepod species on, Aedes larvae under laboratory conditions. Copepods were collected from the pre-identified locations within the districts of Gampaha and Kandy, and identified morphologically. Individual species of copepods were maintained as separate colonies with Paramecium culture and wheat grain as supplementary food. Five adult copepods of each species was introduced into separate containers with 200 larvae (1st instar) of Aedes aegypti. Number of larvae survived in containers were enumerated at 3 hour intervals within a duration of 24 hours. Each experiment was repeated five times. The same procedure was followed for Ae. albopictus. Significance in the variations among predation rates was evaluated with General Linear Modelling (GLM) followed by Tukey's pair-wise comparison in SPSS (version 23). Significant variations in predation rates of studied copepod species were reported (p<0.05), whereby M. leuckarti indicated the highest followed by M. scrassus, while C. languides indicated the lowest predatory efficacy. The effect of different Aedes larval species on the predation rates of copepods remained significant (p<0.05), even though the effect on predatory efficiency was not significant. Based on the findings, both M. leuckarti and M. scrassus, with the highest predatory efficiencies, could be recommended as potential candidates for biological controlling of Aedes vectors in Sri Lanka.


Asunto(s)
Aedes/crecimiento & desarrollo , Copépodos/fisiología , Dengue/prevención & control , Larva/crecimiento & desarrollo , Control de Mosquitos/métodos , Control Biológico de Vectores/métodos , Conducta Predatoria/fisiología , Animales , Vectores de Enfermedades , Ecosistema , Mosquitos Vectores/crecimiento & desarrollo , Sri Lanka
11.
Fish Shellfish Immunol ; 90: 199-209, 2019 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-31048036

RESUMEN

The study of host-parasite relationships is an integral part of the immunology of aquatic species, where the complexity of both organisms has to be overlayed with the lifecycle stages of the parasite and immunological status of the host. A deep understanding of how the parasite survives in its host and how they display molecular mechanisms to face the immune system can be applied for novel parasite control strategies. This review highlights current knowledge about salmon and sea louse, two key aquatic animals for aquaculture research worldwide. With the aim to catch the complexity of the salmon-louse interactions, molecular information gleaned through genomic studies are presented. The host recognition system and the chemosensory receptors found in sea lice reveal complex molecular components, that in turn, can be disrupted through specific molecules such as non-coding RNAs.


Asunto(s)
Copépodos/fisiología , Infestaciones Ectoparasitarias/veterinaria , Enfermedades de los Peces/parasitología , Interacciones Huésped-Parásitos , Salmón , Animales , Péptidos Catiónicos Antimicrobianos/metabolismo , Acuicultura , Quimiotaxis/inmunología , Copépodos/genética , Copépodos/inmunología , Copépodos/microbiología , Infestaciones Ectoparasitarias/parasitología , Infestaciones Ectoparasitarias/fisiopatología , Enfermedades de los Peces/fisiopatología , Inmunidad Innata/fisiología , Microbiota/fisiología , Salmón/inmunología , Salmón/microbiología , Salmón/fisiología
12.
Proc Biol Sci ; 286(1896): 20181664, 2019 02 13.
Artículo en Inglés | MEDLINE | ID: mdl-30963919

RESUMEN

Our traditional view of the interactions between marine organisms is conceptualized as food webs where species interact with one another mainly via direct consumption. However, recent research suggests that understudied non-consumptive interactions, such as behaviourally mediated indirect interactions (BMIIs), can influence marine ecosystems as much as consumptive effects. Here, we show, to our knowledge, the first experimental evidence and quantification of bottom-up BMIIs in plankton food webs. We used observational, modelling and experimental approaches to investigate how behavioural responses to resource availability influence predation mortality on grazers with different foraging strategies (ambushing versus active foraging). A three-level food chain was used: phytoplankton as resource, copepod nauplii as grazers of phytoplankton and a large copepod as a predator. Ambushers showed little change in foraging activity with resource availability, whereas active foragers decreased their foraging activity with increasing resources, which led to a decrease (24-50%) in predation mortality. Therefore, an increase in resources ('initiator') causes behavioural changes in active grazers ('transmitter'), which ultimately negatively affects predator ('receiver') consumption rates. Consequently, increase in resource abundance may result in decreasing energy transfer to higher trophic levels. These results indicate that behaviourally mediated interactions drive marine food web dynamics differently from that predicted by only density-mediated or consumptive interactions.


Asunto(s)
Copépodos/fisiología , Cadena Alimentaria , Herbivoria , Plancton/fisiología , Conducta Predatoria , Rhodopseudomonas/fisiología , Animales , Ecosistema , Modelos Biológicos
13.
PLoS One ; 14(3): e0213931, 2019.
Artículo en Inglés | MEDLINE | ID: mdl-30870509

RESUMEN

Change in the nutritional quality of phytoplankton is a key mechanism through which ocean acidification can affect the function of marine ecosystems. Copepods play an important role transferring energy from phytoplankton to higher trophic levels, including fatty acids (FA)-essential macronutrients synthesized by primary producers that can limit zooplankton and fisheries production. We investigated the direct effects of pCO2 on phytoplankton and copepods in the laboratory, as well as the trophic transfer of effects of pCO2 on food quality. The marine cryptophyte Rhodomonas salina was cultured at 400, 800, and 1200 µatm pCO2 and fed to adult Acartia hudsonica acclimated to the same pCO2 levels. We examined changes in phytoplankton growth rate, cell size, carbon content, and FA content, and copepod FA content, grazing, respiration, egg production, hatching, and naupliar development. This single-factor experiment was repeated at 12°C and at 17°C. At 17°C, the FA content of R. salina responded non-linearly to elevated pCO2 with the greatest FA content at intermediate levels, which was mirrored in A. hudsonica; however, differences in ingestion rate indicate that copepods accumulated FA less efficiently at elevated pCO2. A. hudsonica nauplii developed faster at elevated pCO2 at 12°C in the absence of strong food quality effects, but not at 17°C when food quality varied among treatments. Our results demonstrate that changes to the nutritional quality of phytoplankton are not directly translated to their grazers, and that studies that include trophic links are key to unraveling how ocean acidification will drive changes in marine food webs.


Asunto(s)
Dióxido de Carbono/efectos adversos , Copépodos/metabolismo , Ácidos Grasos/metabolismo , Fitoplancton/metabolismo , Aclimatación , Animales , Copépodos/crecimiento & desarrollo , Copépodos/fisiología , Ecosistema , Femenino , Cadena Alimentaria , Concentración de Iones de Hidrógeno , Masculino , Fitoplancton/crecimiento & desarrollo , Reproducción , Agua de Mar/efectos adversos , Agua de Mar/química
14.
Artículo en Inglés | MEDLINE | ID: mdl-30921652

RESUMEN

Planktonic copepods are a diverse and abundant group of small (~mm sized) aquatic animals that play a critical role in linking the base of the food chain with higher trophic levels. These invertebrates are a primary food source for marine fish larvae. Their ubiquitous presence is thus of vital importance for recruitment of fish stocks and also as promising live feed for finfish production in aquaculture. This paper reviews the application of molecular approaches to understanding copepod physiology, particularly in non-parasitic species. The review includes both targeted gene approaches and untargeted transcriptomic approaches, with suggestions for best practices in each case. Issues particularly relevant to studies of copepods include heterogeneity within species, morphologically cryptic species, experimental artifacts associated with sample handling, and limited annotation of copepod genes and transcripts. The emergence of high-throughput sequencing and associated increased availability of genomic and transcriptomic databases have presented a huge opportunity to advance knowledge of copepod physiology. The research community can leverage this opportunity through efforts to maintain or improve data accessibility, database annotation, and documentation of analytical pipelines.


Asunto(s)
Copépodos/genética , Transcriptoma , Animales , Copépodos/fisiología , Perfilación de la Expresión Génica/métodos , Marcación de Gen/métodos , Secuenciación de Nucleótidos de Alto Rendimiento/métodos
15.
An Acad Bras Cienc ; 91(1): e20170973, 2019 Mar 21.
Artículo en Inglés | MEDLINE | ID: mdl-30916151

RESUMEN

In this study, we analyzed the main distributional features of Scolecitrichidae species in the Southwestern Atlantic Ocean (northern region of Rio de Janeiro State) and determined and described their habitat partitioning, based on a night series of stratified samplings down to a depth of 1,200 m. A total of 18 species from seven genera were identified and grouped according to their depth distribution. Distinct vertical patterns of total density, richness, diversity, and evenness were observed, with a decrease in density and an increase in diversity and richness with increasing depth. The total scolecitrichid abundance was dominated by a few epipelagic migrant species (Scolecithrix danae, Scolecithricella minor, Amallothrix tenuiserrata, and Lophothrix frontalis). The nondominant species were distributed in different habitats in the mesopelagic layer (upper-mesopelagic, mesopelagic, and lower-mesopelagic species) according to their vertical patterns of abundance and occurrence in the two sampling periods (rainy and dry season). The total density of scolecitrichid copepods was positively related to temperature and nitrate, and negatively related to silicate at 1 m depth. The abundance of scolecitrichids copepods in the upper layer with warm and oligotrophic waters supports the hypothesis of the influence of different water masses on the scolecitrichid assemblage. High abundance of appendicularians (Oikopleura longicauda) at 1 m depth in the region implies a high production rate of discarded "houses", an important dietary component for Scolecitrichidae copepods. The observed patterns of seasonal cycles and vertical distribution suggest that the diverse scolecitrichid assemblage in the region may be structured mainly according to the partitioning of vertical habitats and food resources.


Asunto(s)
Distribución Animal/fisiología , Copépodos/fisiología , Ecosistema , Animales , Océano Atlántico , Brasil , Densidad de Población , Lluvia , Estaciones del Año , Análisis Espacial , Temperatura Ambiental
16.
PLoS One ; 14(3): e0214013, 2019.
Artículo en Inglés | MEDLINE | ID: mdl-30901351

RESUMEN

Filter feeding zooplankton are a crucial component of limnic food webs. Copepods and cladocerans are important prey organisms for first-level predators like the common and abundant larvae of phantom midges (Chaoborus sp.). The latter possess a complex catching basket built of head appendages specialized to capture small crustaceans. The predator-prey-relationship of Chaoborus (Diptera, Nematocera) and Daphnia (Crustacea, Cladocera) has been studied in particular detail owing to the daphniids' ability to react upon the threat of predation with inducible defenses. Daphnia pulex expresses so-called 'neckteeth' in the presence of Chaoborus larvae that are discussed as a defensive trait that interferes with the larval head appendages and their effectiveness has been shown in several studies. Nonetheless, mode of function of these neckteeth is not understood and the hypothesis that they interfere with the predator's head appendages still has to be confirmed. To clarify the role of neckteeth in Daphnia, an understanding of the Chaoborus capture apparatus is essential. Here, we present a detailed three-dimensional analysis of Chaoborus obscuripes' larval head morphology as well as a kinematic analysis of the attack motion, which revealed an impressive strike velocity (14 ms to prey contact). The movement of the larvae's head appendages is reconstructed in the three-dimensional space using a combination of high-speed videography, micro-computed tomography and computer animation. Furthermore, we provide predation trial data to distinguish between pre- and post-attack defensive effects in D. pulex. Our findings suggest a combination of pre- and post-attack defenses with an average effectiveness of 50% each. With this study, we quantitatively describe prey capture kinematics of C. obscuripes and take a further step to reveal the neckteeth' mode of function in D. pulex.


Asunto(s)
Cladóceros/fisiología , Copépodos/fisiología , Dípteros/fisiología , Larva/fisiología , Conducta Predatoria/fisiología , Animales , Cadena Alimentaria , Cabeza/fisiología
18.
Syst Parasitol ; 96(2): 207-232, 2019 03.
Artículo en Inglés | MEDLINE | ID: mdl-30747401

RESUMEN

The caligid copepod Caligus lichiae Brian, 1906 is redescribed based on new material collected from the type-host, Lichia amia (Linnaeus), and from a second carangid, Seriola dumerili (Risso), both caught in the Gulf of Iskenderun, Turkey. Key diagnostic characters of both sexes are reported, supported by drawings and scanning electron microscopy images. Despite the commercial importance of its type-host, L. amia, C. lichiae has not been reported since its original description. After detailed comparison with recent descriptions of Caligus aesopus Wilson C. B., 1921, commonly found on S. dumerili, we recognise these two species as conspecific and propose to relegate C. aesopus Wilson C. B., 1921 to a junior subjective synonym of C. lichiae Brian, 1906. Caligus lichiae is a member of the C. confusus group of species and an identification key to species in this group is provided.


Asunto(s)
Copépodos/clasificación , Copépodos/fisiología , Perciformes/parasitología , Animales , Copépodos/ultraestructura , Femenino , Masculino , Mar Mediterráneo , Microscopía Electrónica de Rastreo , Especificidad de la Especie
19.
Syst Parasitol ; 96(2): 171-189, 2019 03.
Artículo en Inglés | MEDLINE | ID: mdl-30747405

RESUMEN

A new clausidiid copepod was found associated with the ghost shrimp Neocallichirus jousseaumei (Nobili) in the Persian Gulf, on the Iranian coast. The new species shares the armature formula of swimming legs 2 to 4 with C. persiaensis, but can be easily distinguished from its congeners by unique characteristics of the females: the prominent spine on endopodal segment 1 of the antenna, the armature of the maxilliped, and the elongated basis of the swimming legs. Distinguishing features observed in males include the distinct projections on the maxilliped and the armature of legs 1 and 4. In addition to traditional light microscopy-based descriptions, confocal laser scanning microscopy (CLSM) was used to obtain high resolution images and 3-D reconstructions of entire copepods. Structures of taxonomic importance that exhibit complex shapes (male maxilliped and female urosome) were scanned to generate 3-D prints that gave valuable insights about female/male interlocking mechanisms. The taxonomic status and host specificity of Clausidium spp. are discussed and a key to valid species is provided.


Asunto(s)
Copépodos/citología , Copépodos/fisiología , Especificidad del Huésped , Animales , Copépodos/anatomía & histología , Copépodos/ultraestructura , Femenino , Océano Índico , Masculino , Microscopía Confocal , Especificidad de la Especie
20.
PLoS One ; 14(1): e0209823, 2019.
Artículo en Inglés | MEDLINE | ID: mdl-30640913

RESUMEN

Climate change is expected to exacerbate upwelling intensity and natural acidification in Eastern Boundaries Upwelling Systems (EBUS). Conducted between January-September 2015 in a nearshore site of the northern Humboldt Current System directly exposed to year-round upwelling episodes, this study was aimed at assessing the relationship between upwelling mediated pH-changes and functional traits of the numerically dominant planktonic copepod-grazer Acartia tonsa (Copepoda). Environmental temperature, salinity, oxygen, pH, alkalinity, chlorophyll-a (Chl), copepod adult size, egg production (EP), and egg size and growth were assessed through 28 random oceanographic surveys. Agglomerative clustering and multidimensional scaling identified three main di-similitude nodes within temporal variability of abiotic and biotic variables: A) "upwelling", B) "non-upwelling", and C) "warm-acid" conditions. Nodes A and B represented typical features within the upwelling phenology, characterized by the transition from low temperature, oxygen, pH and Chl during upwelling to higher levels during non-upwelling conditions. However, well-oxygenated, saline and "warm-acid" node C seemed to be atypical for local climatology, suggesting the occurrence of a low frequency oceanographic perturbation. Multivariate (LDA and ANCOVA) analyses revealed upwelling through temperature, oxygen and pH were the main factors affecting variations in adult size and EP, and highlighted growth rates were significantly lower under node C. Likely buffering upwelling pH-reductions, phytoplankton biomass maintained copepod reproduction despite prevailing low temperature, oxygen and pH levels in the upwelling setting. Helping to better explain why this species is among the most recurrent ones in these variable yet productive upwelling areas, current findings also provide opportune cues on plankton responses under warm-acid conditions, which are expected to occur in productive EBUS as a consequence of climate perturbations.


Asunto(s)
Copépodos/fisiología , El Niño Oscilación del Sur/efectos adversos , Fitoplancton/crecimiento & desarrollo , Animales , Biomasa , Clorofila A/análisis , Cambio Climático , Copépodos/crecimiento & desarrollo , Ecosistema , Concentración de Iones de Hidrógeno , Plancton/crecimiento & desarrollo , Dinámica Poblacional , Salinidad , Estaciones del Año , Temperatura Ambiental
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