Pontellid Copepods Research Articles

Copepods and diatoms: Classic examples of epibiosis along the southeastern Arabian Sea

Exoskeleton of several copepods along the coastal and offshore waters of the Southeastern Arabian Sea provide a convenient habitat for the attachment of epibiotic diatoms, Pseudohimantidium pacificum, Protoraphis sp. and Protoraphis atlantica. P. pacificum was highly host-specific towards corycaeid copepods, whereas the genus Protoraphis showed specificity towards calanoid and pontellid copepods. All the host copepods identified except Labidocera sp. formed a new host record for Protoraphis, with Scolecithrix sp. belonging to an entirely new family, Scolecitrichidae. Taxonomic description, ecological habit, biogeographic distribution, host range, attachment sites and sex preference of the diatoms are described. A high number of associations was observed in females and offshore waters, corresponding to the larger size of the host and the unavailability of non-living substrates along offshore waters. The study suggests the utilization of hosts by the diatoms as a primary habitat. The report is the first along the Arabian Sea, creating baseline data on epibiosis

First assessment of anthropogenic particle ingestion in Pontellid copepods: Pontella mediterranea as a potential microplastic reservoir in the Neuston

Hyponeustonic species, living at the interface between the atmosphere and the oceans, comprise one of the most understudied and vast critical marine biotope, constantly exposed to high concentrations of anthropogenic contaminants and microplastic (MPs). Copepods of the Pontellidae family represent the primary components of this biotic assemblage worldwide, and their interaction with MPs is still unknown. We studied this interaction for the first time in Pontella mediterranea, assessing the ingestion of anthropogenic particles (APs) in 2793 individuals collected by manta trawl in the Northern Alboran Sea.We observed P. mediterranea abundances ranging from 41.67 to 1174.83 ind/m3, with a mean ingestion of 0.11 APs/ind, predominantly composed of MPs. These results confirm the low ingestion values observed for other copepod taxa. However, given its abundance, this species could retain an average of 45.15 and a maximum of 220 APs per m3 of seawater (APs/m3), mostly composed of cellulose acetate and cotton fibers. The abundances of APs were evaluated in surface (0–12 cm) and sub-surface waters (5 m depth) by combining manta trawl and Continuous Underway Fish Egg Sampler sampling. The AP abundances found (surface waters: 0.67 ± 1.04 APs/m3; subsurface waters: 3.85 ± 2.67 APs/m3) were consistent with those previously observed in the Mediterranean basin, confirming that the ingestion values observed in P. mediterranea are not due to a local accumulation of environmental MPs.Results highlight how this neustonic copepod could represent one of the largest reservoirs of APs within the upper layers of the oceans, representing an entry point for these particles within food webs. Considering the worldwide distribution and abundance of this family of copepods, the results are of environmental concern.

Diversity rhythm in pontellid copepods (Pontellidae: Copepoda) from the Covelong coast pre- and post-COVID-19 lockdown, Bay of Bengal

Diversity rhythm in pontellid copepods (Pontellidae: Copepoda) from the Covelong coast pre- and post-COVID-19 lockdown, Bay of Bengal

Key to the Red Sea Labidocera (Crustacea; Calanoida: Pontellidae) copepods, the distribution of the species in various habitats, with special reference to two new records, and a historical correction

Pontellid copepods of the genus Labidocera from the Red Sea are described in the present work. The species are most easily distinguished according to their fifth leg, “P5”, which has a very distinctive shape and is characterized by the presence of an extended claw-like thumb at the proximal end of the exopodite segment. During a survey off the coast of Hurghada, Red Sea, a total of four Labidocera species were identified, two of which were new records for the Red Sea. A historical review showed that a third, presumably new record had already been sampled in the early 1900s but overlooked by previous authors. This increases the total number of species observed in the Red Sea to eight, belonging to three groups. The first is the detruncata group, which includes five species: L. boxshalli, L. detruncata, L. orsinii, L. pavo, and a new record for the Red Sea, L. madurae. The minuta group is the second and includes only one species: L. minuta. The remaining two species, L. acuta and the first record in the Red Sea of L. euchaeta, are included in an unassigned group. All of these species are Indo-West Pacific forms with wide tropical and subtropical distributions. Mistakes can sometimes be made by taxonomists when identifying the presence of a particular species in a specific area, such as the case of denying the existence of L. detruncata in the Red Sea, for which a historical review was carried out in the current work demonstrating its previous existence. Therefore, historical reviews must be continually conducted to evaluate the differences in the spatial and temporal distributions of various species. On the other hand, Habitats with well-balanced ecosystems such as coral reefs are more diverse than those of a competitive nature or that exposed to severe environmental conditions such as seagrass and shallow lagoons.

Blue pigmentation of neustonic copepods benefits exploitation of a prey-rich niche at the air-sea boundary

The sea-surface microlayer (SML) at the air-sea interface is a distinct, under-studied habitat compared to the subsurface and copepods, important components of ocean food webs, have developed key adaptations to exploit this niche. By using automated SML sampling, high-throughput sequencing and unmanned aerial vehicles, we report on the distribution and abundance of pontellid copepods in relation to the unique biophysicochemical signature of the SML. We found copepods in the SML even during high exposure to sun-derived ultraviolet radiation and their abundance was significantly correlated to increased algal biomass. We additionally investigated the significance of the pontellids’ blue pigmentation and found that the reflectance peak of the blue pigment matched the water-leaving spectral radiance of the ocean surface. This feature could reduce high visibility at the air-sea boundary and potentially provide camouflage of copepods from their predators.

Neustonic copepods (Labidocera spp.) discovered living residentially in coral reefs

Pontellid copepods are archetypical representatives of the neuston—the highly specialized community living in the top 5–10 cm of the ocean surface. Their deep blue pigmentation and large eyes are unique adaptations to surface irradiation and carnivory, but poor prerequisites for survival in the transparent waters beneath the sea surface. Here, we report the discovery of three reef-associated representatives of this group—Labidocera bataviae A. Scott, 1909; L. pavo Giesbrecht, 1889; and Labidocera sp.—living residential in coral reefs. We (1) document the presence of Labidocera spp. for two separate coral reefs on two expeditions to Papua New Guinea, (2) describe their migration behavior and substrate preference, and (3) quantify the effects of benthic reef community composition on their abundance. All life stages of Labidocera spp. were 43 to 94 times more abundant at the reef sites compared to offshore sites. Although pontellids are generally considered non-migrators, Labidocera spp. showed discernible diel vertical migrations: living in reef substrates during the day, emerging into the water column at night (sometimes more than once), and returning to the substrate at dawn. Labidocera spp. showed a pronounced substrate preference for coral rubble, microalgae, and turf, over branching coral, massive boulder coral, and sand.

Pontellid copepods, Labidocera spp., affected by ocean acidification: A field study at natural CO2 seeps.

CO2 seeps in coral reefs were used as natural laboratories to study the impacts of ocean acidification on the pontellid copepod, Labidocera spp. Pontellid abundances were reduced by ∼70% under high-CO2 conditions. Biological parameters and substratum preferences of the copepods were explored to determine the underlying causes of such reduced abundances. Stage- and sex-specific copepod lengths, feeding ability, and egg development were unaffected by ocean acidification, thus changes in these physiological parameters were not the driving factor for reduced abundances under high-CO2 exposure. Labidocera spp. are demersal copepods, hence they live amongst reef substrata during the day and emerge into the water column at night. Deployments of emergence traps showed that their preferred reef substrata at control sites were coral rubble, macro algae, and turf algae. However, under high-CO2 conditions they no longer had an association with any specific substrata. Results from this study indicate that even though the biology of a copepod might be unaffected by high-CO2, Labidocera spp. are highly vulnerable to ocean acidification.

A new species of Calanopia (Copepoda, Calanoida, Pontellidae) from the plankton of the central Red Sea

Calanopia tulina sp. nov., a new pontellid copepod, is described from plankton samples collected in Saudi Arabian waters of the Red Sea. The female of the new species differs from other congeners in having the genital operculum located posteroventrally on the genital compound somite and by a slightly asymmetrical leg 5, in which the right leg is slightly shorter than the left one. The male is distinguished by: (1) the presence of a distinct notch on the medial margin of the right prosomal corner; (2) the structure of leg 5, in which the second exopodal segment of the left leg has one medially directed spine and two large laterally directed and curved serrated spines distally; and (3) the first exopodal segment of the right leg has a very small rounded-tip thumb located at the mid-length. The new species is most similar to Calanopia media described from the Red Sea. The presence of the new species in night collection may be due to the diel vertical migration behavior that is known for some species of this genus.

Vertical migration and positioning behavior of copepods in a mangrove estuary: Interactions between tidal, diel light and lunar cycles

Two-hourly zooplankton samplings encompassing tidal (semi-diurnal), diel (24 h), and lunar (4 phases) cycles during the dry (July 2003) and wet (November 2003) monsoon periods were conducted in the Matang estuary to investigate the vertical distribution and behavior of five different groups of copepods (estuarine, euryhaline, marine euryhaline, stenohaline and nocturnal pontellids) in response to the tidal and light regime. Diel vertical migration (DVM) was evident for all copepod groups but the observed patterns differed among species and sampling period (wet or dry and neap or spring tide). Tidally-induced vertical migration (TVM), superimposed by DVM, was observed for estuarine, marine euryhaline and stenohaline copepods but not for euryhaline and nocturnal pontellid copepods. Estuarine copepods tended to ascend during night-flood tide and descent to the bottom during day-ebb tide; this suggests a selective mechanism to penetrate upstream and maintain position in the estuary. In contrast, the marine euryhaline and stenohaline copepods remained at the bottom especially during day-flood tide and ascended into the water column during night-ebb tide; this suggests a selective mechanism to avoid upstream transport. Euryhaline copepods did not respond to tidal advection probably due to their wide range of salinity tolerance, while the large nocturnal pontellid copepods have strong swimming ability. Adaptive vertical migration appears to be a major factor structuring the copepod community in tropical estuaries, and its occurrence in most copepods suggests that neritic marine zooplankton tidally-advected into estuaries and nearshore waters can survive better than previously thought.

Seasonal variation of the neustonic zooplankton community in southern waters of Korea

We investigated the seasonal variation of the neustonic zooplankton community in the surface layer (above 30 cm in depth) of 16 stations in southern waters of Korea from April 2002 to April 2003. In the neustonic community, copepods accounted for 59% of total organisms, as the most predominant group, while other dominant groups were invertebrate larvae, cladocerans, tunicates and fish eggs. Pontellid copepods, a major group of neustonic zooplankton, showed a marked seasonal variation and displayed a significant positive correlation with temperature (P < 0.05). Fish eggs appeared from spring to early summer in the inshore waters while tunicates and oceanic copepods (Eucalanus spp. and Euchaeta spp.) were dominant in the offshore waters during high temperature periods. This suggests that the distribution pattern of the neustonic zooplankton is seasonally affected by the hydrological conditions of in- and offshore waters. The abundance of zooplankton was higher in the surface layer (< 15 cm) than in the subsurface layer (15–30 cm), and was also higher at night than during the daytime. Of the dominant copepod families, the density of acartiid and pontellid copepods was higher in the surface layer than the subsurface layer. The density of acartiid and corycaeid copepods was significantly higher during daytime than nighttime. This indicates that the surface layer in temperate regions may provide a favorable habitat for neustonic copepods despite the dynamic environmental fluctuations.

Very Bright Green Fluorescent Proteins from the Pontellid Copepod Pontella mimocerami

BackgroundFluorescent proteins (FP) homologous to the green fluorescent protein (GFP) from the jellyfish Aequorea victoria have revolutionized biomedical research due to their usefulness as genetically encoded fluorescent labels. Fluorescent proteins from copepods are particularly promising due to their high brightness and rapid fluorescence development.ResultsHere we report two novel FPs from Pontella mimocerami (Copepoda, Calanoida, Pontellidae), which were identified via fluorescence screening of a bacterial cDNA expression library prepared from the whole-body total RNA of the animal. The proteins are very similar in sequence and spectroscopic properties. They possess high molar extinction coefficients (79,000 M−1 cm−) and quantum yields (0.92), which make them more than two-fold brighter than the most common FP marker, EGFP. Both proteins form oligomers, which we were able to counteract to some extent by mutagenesis of the N-terminal region; however, this particular modification resulted in substantial drop in brightness.ConclusionsThe spectroscopic characteristics of the two P. mimocerami proteins place them among the brightest green FPs ever described. These proteins may therefore become valuable additions to the in vivo imaging toolkit.

Labidocera boxshalli sp. nov., a new calanoid copepod (Crustacea; Pontellidae) from the Red Sea

A pontellid copepod, Labidocera boxshalli sp. nov., is described from the Egyptian coast of the northern Red Sea. This species is most readily distinguished from its congeners by the presence of a mid-dorsal process on the female genital double somite, the female fifth leg exopod terminating in two superimposed processes (the ventral of which is shorter), and by the elongated first exopodal segment of the male right fifth leg carrying a stout, blunt-tipped process and a small papilla laterally near the base of the thumb that bears one seta. The new species belongs to the L. detruncata species group, which is distributed mainly in the tropical/subtropical waters of the Indo-West Pacific.

ERRATUM: Vertebrate-like βγ-crystallins in the ocular lenses of a copepod

We previously reported that the ocular lenses of the pontellid copepod Anomalocera ornata possess vertebrate-like β- and γ-crystallins. We cannot repeat our earlier data suggesting that the copepod lens crystallins belong to the β- and γ-crystallin family of proteins. Our new data are consistent with the copepod crystallins being novel proteins.

Diel vertical migration of the marine copepod Calanopia americana. I. Twilight DVM and its relationship to the diel light cycle

Marine copepods commonly exhibit vertical movements in the water column over the diel cycle, termed diel vertical migration (DVM), with the most common pattern being an ascent in the water column to minimum depth around sunset and descent to maximum depth around sunrise. The present study characterized the DVM pattern of the pontellid copepod Calanopia americana Dahl in the Newport River estuary (North Carolina, USA, in July 2003). The estuary is shallow and well-mixed, and the study site (34°43′N; 76°40′W), 1.5 km inside the estuary entrance, is unusual in lying within a gyre where tidal currents are always in the seaward direction. Changes in C. americana vertical abundance were related to spectrally relevant changes in light throughout the diel cycle. Simultaneous measurements of light and zooplankton abundance near the surface (0.5 m depth) and near the bottom (0.5 m above bottom) were made over one 4-h period and two 3-day periods during different phases of the tide. These observations suggest that C. americana undertook twilight DVM in the Newport River estuary; an ascent to the surface occurred at sunset, followed by a descent to near the bottom around midnight, with a second ascent to the surface and then descent to near bottom at sunrise. DVM in C. americana was independent of the tidal cycle, with the initial ascent in the water column at sunset possibly associated with relative rates of irradiance change. Copepod vertical movements were consistent with a night-active endogenous rhythm, and appeared independent of the abundance of predatory chaetognaths, Sagitta spp. In DVM studies with migrators like C. americana that are broadly sensitive to visible wavelengths of light, measuring photosynthetically active radiation may be a reasonable alternative to measuring light in a spectrally relevant photometric unit.

Vertebrate-like ??-crystallins in the ocular lenses of a copepod

The diverse crystallins are water-soluble proteins that are responsible for the optical properties of cellular lenses of animal eyes. While all vertebrate lenses contain physiological stress-related alpha- and betagamma-crystallins, some also contain taxon-specific, often enzyme-related crystallins. To date, the alpha- and betagamma-crystallins have been found only in vertebrate lenses. Here we report lenses from an invertebrate, the pontellid copepod Anomalocera ornata, accumulate betagamma-crystallin family members as judged by immunocytochemistry, western immunoblotting and microsequencing. Our data provide the first example of betagamma-crystallin members in an invertebrate lens, establishing that the use of this protein family as lens crystallins is not confined to vertebrates.

Relationship between mouthpart structures and in situ feeding habits of species of the family Pontellidae (Copepoda: Calanoida)

Pontellid copepods were collected from the surface waters of a tidal front region in the Bungo Channel (the Inland Sea of Japan) in June 1986 to examine the relationship between the morphology of cephalic appendages and gut contents. In particular, two dominant species,Labidocera japonica Mori andPontellopsis yamadae Mori, were compared in detail. Large setae on the second maxillae ofL. japonica possessed two rows of setules at right angles to each seta along its inner margin except a terminal part which was serrated, whereas the inner margin of those setae ofP. yamadae was entirely serrated. Judging from the structure of the mouthparts, especially the second maxillae, the former species seems to employ both suspension and raptorial feeding modes, in contrast to the latter, which may use only the raptorial mode of feeding. InP. yamadae, the first maxilla and the maxilliped are also modified for carnivory. Gut content analysis supported the morphological evidence for feeding differences, and revealed thatP. yamadae is a carnivore preying mainly on copepodids whileL. japonica feeds omnivorously on copepod nauplii and phytoplankton particles. Since the mouthpart structures of congeners are quite similar to each other, the feeding behavior and habits might also be similar. Within the family Pontellidae, the generaAnomalocera, Calanopia, Epilabidocera, andPontella have mouthpart structures similar to those ofLabidocera, whereas the genusPontellina resemblesPontellopsis. Morphological similarities would suggest that the first group of genera employs both suspension and raptorial feeding modes, and thatPontellina is a carnivore likePontellopsis.

The Functions of Eye and Body Movements in Labidocera and Other Copepods

ABSTRACT Male Labidocera have three eyes derived from the nauplius eye. The dorsal pair have large lenses and are fused to give a single mobile eyecup containing a transverse row of 10 rhabdoms. This rhabdom row scans across 35° of the dorsal visual field at rates of up to 3 Hz, and it is suggested that the scanning movements are concerned with the detection of conspecifics. In addition there are movements which enable the eyecups to track a source of light, and these are mediated by three other receptors in each eyecup. The tracking movements are closely linked to tail movements which tend to keep the animal’s back directed towards the light. The total effect is to stabilize both body and eye direction against involuntary disturbance. Other pontellid copepods show similar visually controlled tail movements, but without the eye movements.

Stabilité de constitution chimique élémentaire et richesse protéique d'un copépode hyponeustonique Anomalocera patersoni templeton

Analysis of C, H, and N contents were carried out on samples of natural populations of the hyponeustonic pontellid copepod Anomalocera patersoni Templeton, from the Gulf of Marseilles. The elementary chemical composition of young stages, adult males and females caught at different seasons during several years was compared, using a statistical method. Values of C, H, and N contents against dry weight, and C : N and C : H ratios indicate a great stability of the elementary constitution of A. patersoni during its whole biological cycle and also at different seasons and over several years ( C : N = 3.60 ± 0.01; C : H = 6.09 ± 0.06). A comparison with work already published on copepods shows that A. patersoni is among the richest species in protein content. This high protein content means that A. patersoni may be an important trophic component of the ultrasuperficial biotope in which it often represents a great biomass.

Description of Labidocera farrani sp. nov., a pontellid copepod known from eastern and northern Australian waters, (Crustacea, Copepoda)

Both sexes of a form previously recorded from Australian waters are described, and the species is named after its original discoverer. Features of the new species and of related species from the super-species detruncata, are tabulated and discussed.

Sinking rates of natural copepod fecal pellets

Many pure samples of natural fecal pellets have been collected from mixed small copepods and from the pontellid copepod Anomalocera patersoni in the Ligurian Sea, using a specially designed pellet collection device. Sinking rates of fresh pellets and pellets aged up to 33 days have been determined at 14°C, the mean temperature of the essentially isothermal water column in the Ligurian Sea. Sinking rates of pellets collected during calm sea states increased with increasing pellet volume, but sinking rates of pellets collected during rough sea (Beaufort scale ≃6) showed little correlation with pellet size. Much of the variability in the sinking rate-pellet size relationships was the result of different pellet composition and compaction, but not pellet age. Pellets produced from laboratory diets of phytoplankton and phytoplankton-sediment mixes showed the expected wide variability in sinking rates, with sediment-ballasted pellets sinking much faster than pellets produced from pure algal diets; thus determination of vertical material fluxes in the sea using laboratory-derived fecal pellet sinking rates is unwarranted. Natural pellet sinking data for small copepods and A. patersoni have been combined with similar data for euphausiids, to yield sinking rates of roughly two orders of magnitude over three orders of magnitude in pellet volume. Pellets from small copepods sank at speeds too slow to be of much consequence to rapid material flux to the deep sea, but they undoubtedly help determine upper water distribution of materials. Recalculation of fecal pellet mass flux estimates from the literature, using our sinking rate data for natural small copepod pellets, yielded estimates about half those of previously published values. Earlier studies had concluded that small fecal pellets were of lesser significance to total material flux than fecal matter; our recalculation strengthens that conclusion. Pellets from large copepods and euphausiids, however, have the capability to transport materials to great depths, and probably do not substantially recycle materials near the surface. The fact that the majority of pellets which had previously been collected in deep traps by other workers were of a size comparable to pellets from our large copepods supports the contention that these larger pellets are the main ones involved in vertical flux.