Cyclopoid Copepod Oithona Davisae Research Articles

The establishment of the non-indigenous cyclopoid copepod Oithona davisae in Hamsilos Bay-Sinop, Southern Black Sea, Turkey

The establishment of the non-indigenous cyclopoid copepod Oithona davisae in Hamsilos Bay-Sinop, Southern Black Sea, Turkey

Escape performance in the cyclopoid copepod Oithona davisae

Escaping a predator is one of the keys to success for any living creature. The performance of adults (males, females, and ovigerous females) of the cyclopoid copepod Oithona davisae exposed to an electrical stimulus is analysed as a function of temperature by measuring characteristic parameters associated with the escape movement (distance covered, duration of the appendage movement, mean and maximum escape speeds, Reynolds number). In addition, as a proxy for the efficiency of the motion, the Strouhal number was calculated. The escape performance showed temperature-dependent relationships within each adult state, as well as differences between sexes; additionally, changes owing to the presence of the egg sac were recorded in females. In a broader perspective, the results collected reveal the occurrence of different behavioural adaptations in males and females, adding to the comprehension of the mechanisms by which O. davisae interacts with its environment and shedding new light on the in situ population dynamics of this species.

Ecophysiological and behavioural responses to salinity and temperature stress in cyclopoid copepod Oithona davisae with comments on gender differences

The gender differences in reaction to salinity (3-50) and temperature (6-26°C) stress were studied in the thermophilic cyclopoid copepod Oithona davisae, introduced in the brackish temperate Black Sea since 2001. Both females and males possessed similar salinity tolerance ranges (6–40) irrespective of the salinity change rate, and females displayed a striking osmotic control upon sharp (18-40 and 40-18) salinity shocks. By contrast, the temperature response of males and females were different. Torpidity was recorded at a temperature below 10°C in males collected both in warm and cold seasons, as well as in summer-autumn females whilst in females grown up at the beginning of winter the locomotor parameters were high even at 6°С. The total metabolic rate of summer-autumn and winter females was determined by the level of basal metabolic rate and energy expenditures due to motor activity. In winter females that maintained high activity at low temperature, the total and basal metabolic rates, differing by 2.3 times at all temperatures within the range of 8–28°C, varied in accordance with the temperature coefficient Q10 of about 2, whereas in summer-autumn females at low temperatures total metabolic rate decreased to the basal level. The plasticity of both males and female to wide ranges in abiotic conditions provide an adaptive strategy to sustain the spreading of O. davisae in diverse environments.

New Mediterranean Biodiversity Records 2019

This paper is a collection of novel distributional records of 20 species belonging to 8 phyla (Chlorophyta, Rhodophyta, Cnidaria, Ctenophora, Annelida, Mollusca, Arthropoda and Chordata) from 11 Mediterranean countries, namely, Spain: an additional record of the Canary dentex Dentex canariensis is reported from Spain (Valencia), this is the northernmost record of this species in the Mediterranean; Algeria: the first documented record of Caulerpa chemnitzia is reported from the Algerian coast; France: the first record of the Spotted sea hare Aplysia dactylomela is reported from the eastern coast of Corsica; Italy: the first records of the Lessepsian polychaete Dorvillea similis and the alien bivalve Isognomon legumen are reported from Italian waters while additional records of Mnemiopsis leidyi in the south Adriatic are provided;  Libya: the first record of an alien mollusc Crepidula fornicata is reported from Libyan waters; Malta: multiple sightings of gelatinous species Apolemia uvaria, Phacellophora camtschatica and Physophora hydrostatica are reported for the first time from Maltese waters, as well as the first tentative record of the Orange-spotted grouper Epinephelus cfr. coioides; Greece: an occurrence of a rare Bigeye thresher shark Alopias superciliosus is reported from Hellenic Ionian waters, while the first records of the alien Mertens’ prawn-goby Vanderhorstia mertensi, the recently described cyclopoid copepod Oithona davisae and the alien red seaweed Asparagopsis armata are reported from the Aegean Sea. The presence of the micromollusc Euthymella colzumensis is confirmed for Greece; Cyprus: the first record of the red cornetfish Fistularia petimba is reported from Cyprus; Turkey: the first record of the alien jellyfish Marivagia stellata is reported from south-eastern Turkey; Israel: the first records of the sea nettle Chrysaora sp. in the Levant are reported.

Identification of some common food items in the guts of fish larvae and juveniles in the Black Sea

Over the past decade the positive trends in the average annual number of fish larvae and in the copepod population dynamics in the coastal area of the Black Sea agree. The increased fish larvae abundance is hypothesized due to improvement of their nutrition associated with the drastic increase in number of introduced invasive cyclopoid copepod Oithona davisae. This assumption is difficult to be verified through fish gut content analysis in absence of methodology allowing prey species identification from their fragmentary residual remnants. Our paper offers an original approach to identification of several common copepod prey using specific distinctive features detected on their chitin fragments from guts of fish larvae and juveniles. To identify specific features of the common species from the coastal areas off Sevastopol (Acartia tonsa, Oithona davisae, Longipedia sp., Cyclopina sp.), alive copepods were isolated from the samples and reared as monospecific cultures in laboratory. Images of alive copepods of each species at successive stages of development and their moulted exoskeletons were compared with the images of chitin remnants found in the fish guts. This technique discloses relatively intact specific morphological features remaining undigested in chitin fragments of prey. These species-specific taxonomic features are suggested to be used for trophic analysis of the Black Sea fishes at early stages of development. Application of proposed method is helpful for assessment of qualitative and quantitative composition of consumed prey and selectivity of fish, especially during the changes in zooplankton community structure affecting significantly survival of fish generations.

Feeding rates and prey : predator size ratios of the nauplii and adult females of the marine cyclopoid copepod Oithona davisae

We studied the feeding behavior of the nauplii and adult females of the marine cyclopoid copepod Oithona davisae in the laboratory. Functional response experiments showed that O. davisae can feed on a broad size range of prey but that high clearance rates only occur in a narrow prey size range. Neither the nauplii nor the females were able to feed on Nannochloropsis oculata (2.5 µm), but > 4 µm prey were ingested. The highest clearance rates occurred when the nauplii and females were offered the dinoflagellate Oxyrrhis marina and the ciliate Strombidium sulcatum, respectively. O. davisae females preyed on Acartia grani nauplii but not on nauplii of their own species. Optimal prey : predator size ratios were similar for the nauplii and the females (∼ 10% of the predator's body length) and were higher than those reported for suspension‐feeding calanoid copepods (2–6%). The finding that the nauplii and females of O. davisae feed on relatively larger prey appears to be a consequence of their strict ambush‐feeding behavior, which constrains feeding activity to prey large enough to create hydromechanical signals above the detection threshold. Very high weight‐specific ingestion rates (> 150% d−1) were obtained when O. davisae fed on relatively large prey. Such high daily rations are much higher than those that can be calculated indirectly from egg production. Size measurements of the mouth of O. davisae females indicate that those prey resulting in extreme feeding rates were too large to be swallowed completely and suggest the presence of sloppy feeding in Oithona.

On the foraging and feeding ability of Oithona davisae (Crustacea, Copepoda)

The foraging behavior and feeding ability of the cyclopoid copepod Oithona davisae, using the flagellate Tetraselmis tetrathele as prey organism, were observed microscopically and three dimensionally in a flow-cell. The distance between O. davisae and prey was estimated, and prey in front of the antennules or close to the mandible or mouthparts was ingested. Before attacking, O. davisae either sank or jumped. Both these motions are typical of foraging behavior. The instantaneous perceptive sphere was measured from the ingested prey position, while the encounter rate was estimated from the volume of the perceptive sphere, sinking speed, jump frequency plus swimming speed of prey. The calculated encounter rate was in good agreement with previously reported ingestion rates at low prey concentrations. From encounter rate and natural prey density, we conclude that O. davisae is capable of locating sufficient prey for its demands. Under natural conditions, where prey organisms may not be encountered regularly, the voracious O. davisae will ingest prey frequently when available. Our experimental methodology, devised to quantify the feeding abilities of O. davisae, is applicable to studying the foraging behavior of other copepod species.

Feeding capabilities and limitations in the nauplii of two pelagic estuarine copepods, Pseudodiaptomus marinus and Oithona davisae

In most aquatic ecosystems, copepod nauplii outnumber all other mesozooplankton. Although thousands of studies have examined feeding by later life history stages, the feeding habits of nauplii are poorly known. We offered conspecific adult and naupliar stages of the current‐feeding calanoid copepod Pseudodiaptomus marinus and the ambush‐feeding cyclopoid copepod Oithona davisae 14 species of phytoplankton from various functional and taxonomic groups that spanned a wide size range. Using a novel epifluorescence microscopy method, we calculated an index of gut pigment for copepods fed each phytoplankton species. We also measured adult and naupliar feeding rates on three species of phytoplankton: the cryptomonad Rhodomonas salina, the prasinophyte Tetraselmis suecica, and the diatom Thalassiosira pseudonana, by an improved gut fluorescence method using a microplate reader. Despite their smaller size, weaker swimming and sensory capabilities, and rudimentary feeding apparatus, nauplii fed on a large range of cell sizes and were capable of consuming many of the same phytoplankton as adults.

Lethal and sublethal effects of naphthalene and 1,2-dimethylnaphthalene on naupliar and adult stages of the marine cyclopoid copepod Oithona davisae

Short-term (24 h) exposure experiments have been conducted to determine the effects of two environmental relevant polycyclic aromatic hydrocarbons (PAHs), naphthalene (NAPH) and dimethylnaphthalene (C2-NAPH), on the naupliar and adult stages of the marine cyclopoid copepod Oithona davisae. To resemble more realistic conditions, those exposure experiments were conducted under the presence of food. The naupliar stages evidenced lower tolerance to PAH exposure regarding narcotic and lethal effects than adults. Copepod feeding activity showed to be very sensitive to the presence of the studied PAHs, detrimental effects occurring at toxic concentrations ca. 2–3 fold lower than for narcotic effects. In addition we report PAH-mediated changes in cell size and growth rate of the prey item, the heterotrophic dinoflagellate Oxyrrhis marina, that could indirectly affect copepod feeding and help explain hormesis-like responses in our feeding experiments.

Effects of freshwater flow on environmental factors and copepod density in the Chikugo estuary, Japan

This study describes the effects of freshwater flow on the major environmental parameters (temperature, salinity, turbidity, chlorophyll- a and phaeopigment) and the density of the two most dominant copepods, a calanoid copepod Sinocalanus sinensis and a cyclopoid copepod Oithona davisae, in the Chikugo River estuary in Ariake Bay, Japan. Freshwater flow negatively and significantly influenced salinity and phaeopigment but the influence on temperature, turbidity and chlorophyll- a was not significant. Freshwater flow also negatively and significantly influenced the distance of turbidity maximum from the river mouth. Density of S. sinensis which is distributed in the upstream areas was negatively and significantly influenced by freshwater flow while the density of O. davisae which is distributed in the downstream areas was not influenced by freshwater flow. The effects of freshwater flow appear to be associated with the spatio-temporal patterns of the dependent parameters. The strongest influences of freshwater flow occurred at the upper part of the estuary within 1–7 days and the influences weakened with space and time.

Mate finding, mating, and population dynamics in a planktonic copepod Oithona davisae: There are too few males

Three‐dimensional (3D) video observations of free‐swimming copepods revealed the mechanisms of mate finding in the cyclopoid copepod Oithona davisae (cephalothorax length 0.33 mm). The females are ambush feeders and spend almost all of their time sinking slowly through the water, interrupted by 0.5–1‐mm‐long jumps every few seconds. The sink—jump behavior distributes produced pheromones along an intermittent trail. Males spend about half of their time ambush feeding, and half of their time cruising rapidly (50 body lengths s−1), searching for female signals. On encountering a pheromone patch, the male starts circling rapidly (up to >100 body lengths s−1) around the patch, apparently to find subsequent patches and, eventually, the female. The pursuit may last several tens of seconds, and ends by the male capturing the female or losing the track. Observed reaction distances and male motility patterns were combined with a simple encounter model to estimate a matesearch volume rate of 4.4 L d−1. The males have a rather limited mating capacity, 0.9 females male−1 d−1, even when mate‐encounter rate is not limiting. Field observations of abundances, combined with estimates of mortality and mate‐search and mating capacities, predict that only approximately one‐third of the females should be fertilized. This is consistent with field observations, and suggests that population growth in this species is severely constrained by fertilization limitation. Fertilization limitation may apply more generally to populations of pelagic copepods, and may partly account for the frequent observation that female copepods produce sterile eggs, even during periods of a plentiful food supply.

Feeding of the chaetognath Sagitta crassa Tokioka in heavily eutrophicated Tokyo Bay, Japan

Sagitta crassa is the only autochthonous chaetognath in Tokyo Bay, central Japan. We analyzed the gut contents of S. crassa at a fixed station in May and September 1997. The species fed on prey organisms whose body widths were in a range between 1.4-6.0% of the length of S. crassa. Prey with body widths less than 2% of the length of S. crassa were minor components of the gut contents. Although the cyclopoid copepod Oithona davisae was abun- dant in the water column, the prey selectivity of S. crassa on O. davisae was low. Our results suggest that S. crassa con- sumes catchable prey organisms that are larger and easier to detect. As planktonic species diversity in the Tokyo Bay ecosystem is low, it has been assumed that a simple trophic pathway from the most dominant primary consumer O. davisae to the secondary consumer S. crassa exists. However, such a simple assumption is inadequate to understand the prey-predator relationships and food-web dynamics in Tokyo Bay.

Seasonal variations in biomass, growth rate and production rate of the small cyclopoid copepod Oithona davisae in a temperate eutrophic inlet

Seasonal variations in biomass, growth rate and production rate of the small cyclopoid copepod Oithona davisae in a temperate eutrophic inlet

Seasonal variations in biomass, growth rate and production rate of the small cyclopoid copepod Oithona davisae in a temperate eutrophic inlet

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 163:37-44 (1998) - doi:10.3354/meps163037 Seasonal variations in biomass, growth rate and production rate of the small cyclopoid copepod Oithona davisae in a temperate eutrophic inlet Shin-ichi Uye*, Kazuhiro Sano Faculty of Applied Biological Science, Hiroshima University, 4-4 Kagamiyama 1 Chome, Higashi-Hiroshima 739-8528, Japan *E-mail: suye@ipc.hiroshima-u.ac.jp We investigated the seasonal variations in biomass, somatic growth rate and production rate of the small cyclopoid copepod Oithona davisae in Fukuyama Harbor, a eutrophic inlet of the Inland Sea of Japan. The carbon biomass of the population, excluding nauplii, was lowest in early spring and increased exponentially in early summer to a maximum of 92.2 mg m-3 in mid-June. Thereafter, it was relatively high, except for a mid-summer decline, until fall. The specific growth rates of naupliar and copepodite stages were estimated from their body weight increments and stage durations, assuming that in this highly eutrophic inlet growth is food-satiated for this species. They increased exponentially with increasing temperature, ranging from 0.088 to 0.357 d-1 for nauplii and from 0.060 to 0.446 d-1 for copepodites within the annual temperature range of 8.9 to 28.2°C. The production rate as a sum of somatic growth rate of copepodites and egg production rate of adult females varied similarly to, but showed a wider range than, the biomass variation. Annual integrated carbon production was 650 mg m-3 yr-1, or 4.88 g m-2 yr-1, 94% of which was attained between June and October. Of the production, copepodite somatic growth and female egg production comprised 75 and 25%, respectively. O. davisae contributed 26% of the annual copepod community production in Fukuyama Harbor. Biomass · Growth · Production · Cyclopoid · Oithona · Inland Sea of Japan Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 163. Publication date: March 12, 1998 Print ISSN:0171-8630; Online ISSN:1616-1599 Copyright © 1998 Inter-Research.

Seasonal reproductive biology of the small cyclopoid copepod Oithona davisae in a temperate eutrophic inlet

Seasonal reproductive biology of the small cyclopoid copepod Oithona davisae in a temperate eutrophic inlet