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Zagami, Giacomo, Stanković, David, Bonanzinga, Vincenzo, Costanzo, Giuseppe (2021): Paramisophria walteri a new Arietellidae (Copepoda, Calanoida) from Midway Island. Journal of Natural History 55 (25-26): 1619-1637, DOI: 10.1080/00222933.2021.1948127, URL: http://dx.doi.org/10.1080/00222933.2021.1948127

Composition, density and specimen sizes of pelagic polychaete assemblages were analyzed in the Southern Adriatic Sea. The study was based on finely stratified vertical (0–1100 m) and spatial sampling (17 stations) representing spring conditions. Holoplanktonic polychaetes were distributed in both neritic and pelagic waters, although the highest densities were observed along the Otranto Channel. Analysis of the size frequency distribution revealed a trend with depth only for some species. Spatial distribution of holoplanktonic polychaete density was not related to bottom depth, being the organisms mainly concentrated in the epipelagic layer (0–100 m). The most abundant species showed maximum values below or within the thermocline and within the Deep Chlorophyll Maximum or just above it. Relations between polychaete presence and the underlying oceanographic mechanisms regulating the circulation in the Otranto Channel were discussed. The presence of several non-determined polychaete larvae (e.g. Syllidae) in the pelagic waters at 800–1100 m depths suggests the importance of the role of Levantine waters as main actual and potential carrier of species in the area, though a relevant contribution comes also from North Adriatic dense waters through deep spilling and cascading in the Southern Adriatic pit. These findings increase the knowledge on holoplanktonic polychaetes ecology within the South Adriatic Sea, and represent significant data in the monitoring of changes in biodiversity.

In this paper, we identify some sponge specimens collected in the Faro Lake in Sicily, and belonging to Haliclona (Halicoclona) by using morphological analysis accompanied by molecular analysis through amplification of several molecular markers (18S and 28S rRNA, CO1 and ITS). The samples are identified as. H. (Halichoclona) vansoesti de Weerdt, de KluijverGómez, 1999, a species native to the Caribbean, and therefore this is the first record of an alien species of the Demospongiae class (Porifera) from the Mediterranean Sea. This presence can be ascribed as results of global change (mainly global warming) that are affecting marine environment.

Since 2007, the non-indigenous calanoid copepod Pseudodiaptomus marinus Sato, 1913 has been increasingly recorded in numerous European sites, spreading at an unexpectedly fast pace over a short time-span. This species presents specific biological and behavioural traits which make it of particular interest for ecological and applied research topics. On 29–30 January 2018, 29 scientists from nine European Countries established the EUROBUS (Towards a EURopean OBservatory of the nonindigenous calanoid copepod Pseudodiaptomus marinUS) Working Group (WG). This WG aimed at creating a European network of institutions and researchers working on the various aspects of the biology and ecology of P. marinus, with an open forum where sharing experience and know-how among WG participants. This brought to an updated distribution map of P. marinus in European waters, as well as to the identification of priority research lines and potential joint initiatives under the WGEUROBUS umbrella. This contribution, stemming from the experts participating at the WG, represents the manifesto of the current and future initiatives developed within WGEUROBUS. info:eu-repo/semantics/publishedVersion

Zooplankton represents a key contributor to the ocean biological pump through its consumption of sinking and suspended carbon. A specific and highly sensitive method to evaluate zooplankton carbon requirement from the sinking flux is through the estimation of the activity of the electron transport system. The present study was carried out from samplings in 2006, and it was focused on the spatial 200-0 m zooplankton carbon demand across 24 sampling stations, along the Mediterranean Sea, from the island of Crete to the Strait of Gibraltar. Its potential day/night variability was evaluated. The zooplankton composition, abundance and biomass were investigated. The carbon demand per unit zooplankton biomass indicates geographical and diel differences among the sampling stations. A higher mean carbon demand was seen for the western Mediterranean with respect to the eastern Mediterranean, which can be justified through the observed ratio of gelatinous:crustacean taxa and the water temperatures recorded. Higher carbon demand was measured in samples collected during the dark hours. The relation to the presence and abundance of actively migrating euphausiids and copepods was discussed. A comparison with data from another of our study carried out in the same study area but in another seasonal period was done.

Copepod community structure was investigated every 6 h during a 24-h cycle at a fixed station in the open Ligurian Sea during a BioLig cruise (May 2013), using a BIONESS multiple-net sampler. The vertical distribution and diel vertical migration in the 0–1300 m water column are described for the main copepod species. Cluster analysis identified three distinct layers within the water column, with each characterised by a different species composition. The differentiation of the species composition for the 0–200 m, 200–600 m and 600–1300 m layers indicates the epipelagic, mesopelagic and deep communities, respectively. The epipelagic community was composed of numerous weak diel vertical migration species that were characterised by low abundance. These included a few dominant coastal species, which with their high abundance, spread into the open waters of the Mediterranean Sea during the spring-summer period. The mesopelagic community was composed of the highest number of species, which mainly inhabited the intermediate waters, with a limited number that showed significant diel vertical migration. The deep community included a few mesopelagic species, which were characterised by wide vertical distribution, with the upper limits reaching into the mesopelagic layers. Among the deep community species, only Lucicutia longiserrata showed an upper limit below 800 m in depth, and thus it can be considered to be the only true deep copepod species that occurs in the Mediterranean Sea. None of the deep community species showed diel vertical migration. Our data reveal discrete layers within this water column that are characterised by different communities, and that show distinct trophic relationships and life strategies. The species vertical distribution patterns showed bimodal distribution, ontogenetic migration, and downwards seasonal migration of the overwintering Calanus helgolandicus stage C5 copepodites, as discussed with regard to the physicochemical and biotic factors.

The present study provides insight into specific zooplankton oxygen and carbon demands (per unit biomass) and community zooplankton respiration and carbon requirements in the Ross Sea (Antarctica). In the literature, there is a lack of data in this area. The role of mesozooplankton in carbon remineralisation in coastal and pelagic environments was evaluated. The zooplankton composition, abundance and biomass were analysed. In the marine carbon cycle, zooplankton from the epipelagic realm has a key role. Estimation of the electron transport system activity represents a specific and highly sensitive method to evaluate the zooplankton carbon requirements from the sinking flux as an indication of the respiratory activity. We focus here on 26 sampling stations in the western sector of the Ross Sea, in which the 0–250-m layer was investigated during the austral summer of 2014. The oxygen consumption from the electron transport system analysis was converted into carbon demand. Differences in carbon requirements were observed, and their relationships to zooplanktonic composition and abundance were investigated, along with their relationships to seawater temperature, food availability, non-living specimens and pteropod faecal pellet abundance. A positive correlation between carbon demand and temperature was highlighted. The change in copepod community composition was relevant in terms of species and relative size ranges. The zooplankton biomass ranged from 41.25 to 171.46 mg m−3 among the stations, which is in agreement with the late summer trophic condition, with higher values for the more coastal stations. Positive correlation between zooplankton biomass and community metabolism per day was revealed. With its recycling of the particulate organic material that originates in the epipelagic layer, the zooplankton compartment participates in the decrease in the input of material, mainly in the two coastal areas investigated, with respect the more pelagic zone.

Diatoms are key phytoplankton species in the world oceans and essential in the transfer of energy through marine food chains. Their beneficial role has been questioned after the discovery that some diatom species produce teratogenic compounds such as polyunsaturated aldehydes and other oxylipins that induce abortions, poor larval development and high offspring mortality in many invertebrates. To test whether maternal and post-embryonic diatom diets affected development in the copepod Paracartia latisetosa , we carried out experiments in which the PUA-producing diatom Skeletonema marinoi (SKE) was fed to this copepod species. Controls were run with the dinoflagellate, Prorocentrum minimum (PRO), which does not produce any of these compounds. Four treatments were tested: both mothers and progeny always fed on either SKE or PRO, and those in which mothers received either PRO or SKE, and neonates were switched to the other diet. Our results show that a SKE/SKE diet induced lower egg production and egg viability, as well as slower embryonic development than the control diet. Naupliar development was negatively affected with the diatom diet which blocked the metamorphosis of larvae at N3, 4 days after hatching, compared to the control diet that allowed for normal naupliar development in 10 days. Nauplii reared on PRO and spawned by females fed on SKE were able to complete development, but only after 11 days, whereas larvae reared on SKE spawned by females fed on PRO were arrested at the N5 developmental stage, 12 days after hatching. Apoptotic TUNEL-positive nauplii were detected with the SKE diet, indicating imminent death. Significant differences were also recorded by comparing biomass of equivalent naupliar stages obtained for each treatment, and the overall mean biomass female − 1 day − 1 for each diet. Growth inhibition due to oxylipin-producing diatoms may have important consequences on prey–predator relationships and on the biomass flux through marine food chains.

A new species of the calanoid copepod genus Paramisophria T. Scott, 1897 is described from the Egyptian sublittoral zone of the Red Sea. Paramisophria aegypti sp. nov. appears to be closely related to the species Paramisophria ammophila and Paramisophria platysoma. Paramisophria aegypti differs from P. ammophila in having two unequal lateral setae plus one long terminal process and two tiny equal lateral setae plus one long terminal process on the third exopodal segment on the male right and left fifth legs (vs three terminal processes increasing in size inward on both male fifth legs). Paramisophria aegypti can be distinguished from P. platysoma in the following characters: prosome symmetrical (vs extreme asymmetry); third exopod segment of the right leg completely separated from the second segment and bears two unequal lateral setae plus one long terminal process (vs partially fused to the second segment and bears four terminal processes increasing in size inward); third exopod segment of the left leg with two lateral setules and one long terminal process (vs two lateral setules, one short outer medial process and one long terminal process); endopodal lobes of the female legs 5 bear one long plumose seta (vs setae are lacking).http://www.zoobank.org/urn:lsid:zoobank.org:pub:C0A92BF9-2306-4A35-AA39-CE3B5865A396

Transitional water ecosystems, like brackish coastal lagoons, provide important services but are subjected to several anthropogenic impacts that can initially lead to biodiversity modifications and then to critical alterations of ecosystem processes. Assessment and monitoring of the health status of these ecosystems is extremely important. This study reports the case study of “Capo Peloro” lakes (southern Italy), where ecotoxicological biomarkers in the key fish species Atherina boyeri have been used to reveal potential contamination in a transitional water ecosystem. The goal was to detect changes that occurred after the summer season, when the surrounding human population significantly increases, with the consequent enhancement of anthropic pressures. Lake Trasimeno, a reference protected site, was also selected. This study is the follow-up of a previous one carried out in the same environment reporting biomarkers employed on the copepod species Paracartia latisetosa, on which Atherina boyeri feeds. The main aim of the present study was to test the responses given by the same type of contamination in a planktivorous fish species, which occupies a higher trophic level. Several biochemical and genotoxic biomarkers were evaluated: Acetylcholinesterase (AChE), Benzo(a)pyrene-monooxygenase (BPMO), Polycyclic Aromatic Hydrocarbons (PAH) metabolites in bile, Erythrocytic Nuclear Abnormalities (ENA) assay. This study confirms the contamination already shown in P. latisetosa from pesticides and carbamates, and/or polycyclic and polyhalogenated aromatic hydrocarbons, heavy metals, surfactants in both “Capo Peloro” lakes. A higher concentration of contaminants was demonstrated in early autumn with respect to the summer season, due to enhanced anthropogenic activities around and on the lakes. This study highlights that, although “Capo Peloro” lakes and Lake Trasimeno are protected areas, they are affected by environmental degradation. This study also confirms the benefits gained with a biomarker approach in monitoring transitional water ecosystems.

Changes in the composition and biomass distribution of deep-living zooplankton over wide gradients of depth (0–1300 m) have been analyzed in the Central Ligurian Basin (Northwestern Mediterranean Sea), seeking the environmental variables responsible for these changes. Spring vertical distribution (early May 2013) and diel vertical migration (DVM) of some key species of macroplankton and micronekton communities were studied every 6 h during a 24 h cycle. The hauls, performed with the multiple opening/closing 230 µm BIONESS net system, made possible a detailed description of the vertical distribution of twenty-three species: one siphonophore, one pyrosomid, one salp, three pteropods, four amphipods, one mysid, eight euphausiids, two decapods, two fishes. Cluster analysis performed on major species of macroplankton and micronekton community assemblage mainly highlighted the presence of four well defined assemblages, based on the depth range in the water column: 0–60 m, 60–100 m, 100–600 m and from 600 to 1300 m. During daytime, vertical distributions of biomass exhibited similar profiles, with maxima in the 0–60 m layer. Highest abundances were recorded between 20–40 and 40–60 m depth, at midnight and in the morning. The highest values of both biodiversity and number of species were found in a deeper layer comprised between 400 and 600 m. Most of the species showed similar distributions throughout the sampled area, either with typical non-diel-migrating characters such as the euphausiid Stylocheiron longicorne and the fishes Cyclothone braueri and C. pygmaea, or with clear diel-migrant behaviour (e.g. the siphonophore Chelophyes appendiculata and the euphausiid Euphausia krohni). Some species (e.g. Vibilia armata, Phronima sedentaria, Scina crassicornis, Salpa fusiformis, Cavolinia inflexa, Gennadas elegans) exhibited a bimodal vertical distribution that could be attributed to different causes able to influence and modify their vertical migration. The lower values of chlorophylla concentrations found in the present studyinthe month of May corresponds to the transition period from a mesotrophic system to a rather oligotrophic one. Temperature and chlorophyll were the variables that principally influenced the distinction between shallow (0–60 m) and deep communities. Below 60 m depth, the dissolved oxygen and salinity become the most important variables affecting the zooplankton community.

Quantitative sampling of zooplankton communities from ice-covered waters presents many technical and logistic difficulties. Currently available techniques enable only vertical tows through relatively small ice holes, and the filtered volumes are generally low. For these reasons, we developed and tested Micro-Net Environmental Sampling System (MicroNESS), an innovative small-sized opening–closing multinet device carried by a ROV for horizontal and oblique sampling of the under-ice zooplankton community. MicroNESS design ensures a filtration efficiency close to 90 % due to the relevant filtration open area ratio (~4) and exhibited only limited effects of clogging and avoidance for optimal speed of 0.35 ms−1 and towing duration not longer than 14 min with mean filtered volumes in the order of 11 m3. MicroNESS was successfully tested in Terra Nova Bay (Antarctica). A total of 96 tows were carried out to sample the zooplankton in the waters below the 2.6-m-thick pack ice, far from the ice hole, at selected depths (3.5, 4.5, 5.0, 6.0, 7.0, 10.0 and 20.0 m). Overall, more than 70,000 specimens were identified, mostly copepod taxa, which showed a size range from the small Stephos longipes nauplius stage I (0.11 mm) to the large adult females of Calanoides acutus (4.8 mm). The comparison among the ice-associated copepod communities collected by MicroNESS and those of three traditional sampling techniques showed that MicroNESS can provide useful insights about changes in composition, biomass and particle size structure of this key plankton component, especially on a short timescale during ice melting.

Surface-dwelling colonies of Velella velella occur throughout tropical to cold-temperate oceans of the world and sometimes are stranded in masses along hundreds of kilometers of beaches. Large-scale blooms in the Western Mediterranean Sea in 2013 and 2014 allowed the study of diet, prey digestion times and predation rates. Gastrozooid content analyses showed that 59% of the 769 identified prey were euphausiid larvae (calytopsis and furcilia) captured at night. Copepods (41%), fish eggs (2.2%) and larvae (0.5%) were captured both at day and night. Digestion times at ambient temperature (similar to 17 degrees C) of calytopsis, furcilia and copepods were estimated to be >6.5, 4.4 and 3.9 h, respectively. Estimated prey consumption was substantially lower in 2014 than in 2013 (41 vs. 75 prey day(-1) colony(-1)). Velella velella and other gelatinous species bloomed in the Mediterranean Sea and the northeastern Atlantic and Pacific oceans in 2013 and 2014. Because of the wide distribution of V. velella colonies, their mass occurrences, potential importance as predators and competitors of fish, additional production from symbiotic zooxanthellae and stranding on beaches, they could be important in open-ocean carbon cycling and in transport of pelagic production to landmasses.

The Strait of Messina is certainly a focal area for the biological cycle of the jellyfish Pelagia noctiluca in the Western Mediterranean Sea. By means of both original and literature data, a conceptual model outlining the biological cycle of this species is proposed. P. noctiluca reproduces from late winter to late spring in the Aeolian Island Archipelago. From late spring to early summer, currents transport newly produced young individuals (20-30 mm bell diameter) eastwards, towards the Strait. The Strait of Messina ecosystem is not a suitable reproduction area for its intense hydrodynamism that would surely lead to a very low reproductive success due to gamete dispersion. This area, however, represents an optimal site for growth, due to its intensive primary and secondary production, but also for an optimal temperature range, lower in summer and higher in winter in respect to the surrounding basins. Pelagia remains all the summer inside the Strait, increasing in bell diameter (50-70 mm) and biomass. Subsequently, in late summer-early autumn, the mature specimens, taking advantage of a typical autumnal downwelling transport, move to deep Tyrrhenian waters where overwinter, to upwell in the Aeolian Archipelago by late winter to start a new cycle.

Transitional water ecosystems can be exposed to high levels of anthropic pressure. The main aim of this study was to present the ‘Capo Peloro’ lakes (southern Italy) case study, which highlights the advantageous use of ecotoxicological biomarkers in key copepod species, to reveal potential contamination in transitional water ecosystems. The focus was on changes that occur after the summer season, as during the summer, the surrounding human population increases significantly, with the consequent enhancement of anthropic pressures. Biomarkers were defined to monitor the zooplankton copepods Paracartia latisetosa, Acartia tonsa and Oithona brevicornis. Acetylcholinesterase, lipid peroxidation, and benzo(a)pyrene-monooxygenase activities were determined. P. latisetosa, A. tonsa and O. brevicornis show linear increases in their acetylcholinesterase activities with increasing concentrations in sample homogenates, which defines their high metabolic rates, and thus the suitability of these species as bioindicators. Biochemical alterations in these species induce changes in their biological attributes that can also lead to their disappearance, with a cascade of consequences for the higher trophic levels in the food chain. These data indicate that for the two lakes of Capo Peloro there is contamination by pesticides, carbamates and polycyclic and polyhalogenated aromatic hydrocarbons. This occurs mainly at the end of the summer season, and only affects the species of the low trophic levels. This case study shows the benefits provided by this biomarker approach as applied to zooplankton species, to monitor transitional water ecosystems and to estimate their toxicological risk, and thus to provide an early warning signal for loss of ecosystem integrity.

This study describes for the first time the feeding behaviour and mesopelagic food consumption of adult Trachurus picturatus in the Strait of Messina (central Mediterranean Sea), where the distinctive hydrodynamic regime and the lunar cycle influence food availability for this predator. Indeed, the Strait of Messina is characterized by the upwelling of colder, saltier and nutrient-rich Levantine Intermediate Water, supporting the congregation and abundance of the mesopelagic community. Despite the commercial importance of T. picturatus in the Mediterranean and Atlantic fisheries, its trophic ecology is almost unknown. Overall, 262 specimens of T. picturatus were collected from small-scale fisheries of the Strait of Messina (September 2016–August 2017) and their stomach content was examined to investigate dietary composition and feeding strategy. Although the absence of a dominant prey item ruled out specialized predatory behaviour in T. picturatus, mesopelagic prey dominated the diet of this species and a significant fraction of food (more than 80% in terms of Index of Relative Importance) was represented by euphausiids and mesopelagic fish. The predator exploitation of mesopelagic prey resources was analysed, considering the ecological implications of the hydrodynamic regime of the study area, which is strongly influenced by upwelling processes linked to the lunar cycle. For this reason, we tested and confirmed the hypothesis that moon phases could influence the food intake of T. picturatus and seasonal variations in the diet as well as size-related dietary shift were also observed.

To provide evidence of the inadequacy of using conventional sampling methods to study mesozooplankton community structure in confined environments, samples from a Mediterranean meromictic coastal lake were taken using 80-μm and 200-μm mesh nets towed at three different depths (0–18 m). Mesh size significantly affected the description of the community structure of the collected zooplankton. The 80-μm-mesh catch revealed for the first time in such an environment the overwhelming abundance of the copepod species Oithona brevicornis, as two orders of magnitude greater than recorded for the 200-μm-mesh catch. The other dominant species were Paracartia latisetosa and Pseudodiaptomus marinus, which were more efficiently sampled with the 200-μm mesh. These showed a summer abundance peak for P. latisetosa near the surface layer, and for P. marinus in the deepest stratum, close to the anoxic layer. Copepod nauplii and bivalve larvae were more efficiently caught with the 80-μm-mesh, and accounted for most of the zooplankton in winter, and showed the highest loss percentage of abundance between the two mesh-size catches. The differences in the assemblages reflect different diversity patterns, with peaks in summer and winter for the communities collected with the 80-μm-mesh and 200-μm-mesh, respectively. These findings imply the need for the development of a commonly used sampling method with paired nets, to correctly take into account both the large and small fractions of the mesozooplankton in the study of closed and semi-enclosed coastal environments, and to obtain data that can be better compared across studies.

The shallow-living, bentho-pelagic copepod species Pseudocyclops umbraticus was collected seasonally during nighttime in the brackish waters of Lake Faro (north-eastern Sicily). It showed marked seasonal fluctuations in population abundance, with maximum numbers occur- ring in summer. In the laboratory, mean daily egg production rates (EPR) of P. umbraticus were positively correlated with temperature, with values ranging from (mean ± SD) 2.3 ± 6.3 eggs female �1 d �1 at 14°C to 6.1 ± 10.2 eggs female �1 d �1 at 24°C. In terms of total egg production over the entire female lifespan, maximum values occurred at 14°C and minimum at 24°C. At 12 and 32°C, females were able to survive, but they stopped egg production. Temperature also dramati- cally affected female copepod lifespan, which was shorter at higher temperatures. Development time for the eggs de creased with increasing temperature, as did development time from egg to adulthood. Recruitment rate was low at lower temperatures. The distinctive egg-laying behaviour of P. umbraticus is described here for the first time. The EPR in P. umbraticus is relatively low com- pared to other pelagic copepods, but within the ranges reported for egg-carrying species. Greater fecundity at higher temperatures compared to other subtemperate species indicates that P. umbraticus is well adapted to the higher temperatures of coastal brackish basins, where it con- tributes to the bio diversity of the plankton community at night as it migrates from the substratum into the water column.

The present study focus on some aspects of zooplankton structure in the Alcantara River (Sicily, Italy), in relation to environmental factors. Zooplankton samplings were performed in spring in four sites, located from up- to downstream along the river course. Four low-flow velocity station points were chosen along a transversal river section in each site. Samples were taken from all station points in the four sites by two different mesh sizes (55 and 100 mm) rectangular nets. Rotifer abundances were an order of magnitude higher in 55 mm mesh size samples than in 100 mm mesh size ones. The two communities also resulted significantly different (ANOSIM test, r= 0.212; P= 0.1%). Generally, low abundances (from 3470 i 5133 to 422 i 474 ind.m x3 ) were explained by low chlorophyll a concentration and the high- flow regime of this river. Rotifer dominated the zooplankton community. Cladocerans, copepods and nauplii occurred with considerably lower abundances than rotifers. However, the relative contributions of these taxa to total abundances depended on the mesh sizes used. Euchlanis and Adineta genera exhibited the highest abundances in the rotifer assemblage. Conductivity alone or in association with temperature and dissolved oxygen was the most important environmental factor affecting rotifer community distribution. Cephalodella sp., Lepadella sp. and Trichotria pocillum showed a high positive relation to pico-plankton, showing this fraction as a possible rotifer food item. This paper demonstrated a higher efficiency of the finest net to characterize riverine zooplankton community that increases from up to downstream in terms of abundances and diversity.

The main aim of this work was to identify zooplankton assemblages by means of statistical testing and associate them with hydrographic properties of the Strait of Magellan and its microbasins. Zooplankton samples were collected by the R/V Cariboo in late austral summer 1991. Nineteen stations were sampled by BIONESS from the surface layer to 900 m depth, along the main longitudinal axis of the Strait of Magellan. There was a marked regional-scale pattern in zooplankton species diversity and richness, related to the hydrographical features of the Strait and its sub-basins. Six groups of samples were identified by cluster analysis in terms of zooplankton structure, and related to sea-water properties of temperature, salinity, and Chl a (Sperman’s correlation coefficient). Plankton assemblages of the Strait of Magellan seem closely linked to the remote sub-Antarctic and adjacent ocean biota, but populations may have independent evolutionary lines and population dynamics.

During an autumn oceanographic cruise in October 2004, 87 zooplankton samples were collected from 12 sites, located along inshore–offshore sections around the Egadi Island Archipelago, a central Mediterranean key region. Zooplankton samples were taken by the electronic multinet BIONESS, equipped with a multi-parameter probe system in order to measure simultaneously physico-chemical and biological factors (temperature, salinity, dissolved oxygen and fluorescence). Three different water masses were identified from physico-chemical parameter analysis: MAW (0–50 m) widespread all around the study area; a water mass, which is most likely a mixture of western and eastern-origin waters, up to 300 m depth; and LIW in the 300–600 m layer, with a core salinity of 38.72–38.74 at the most offshore stations. Spatial diversity patterns of copepod assemblage were examined using species richness and Shannon–Wiener diversity indices. 107 copepod species were identified. Four major sample groups were identified by cluster analysis, differing in species composition and abundances in relation to the depth and in-offshore environments. They seemed to be only partly related to the different water masses and significantly correlated to temperature and salinity. In the entire study area, the copepod abundances were markedly lower than those reported for other regions of the Mediterranean Sea, but the species richness was relatively high, and similar to the richest Mediterranean areas. This is probably due to geographical position of the Egadi Island Archipelago at the entrance of Sicily Channel, where water mass exchange between Eastern and Western basins occurs.

The shallow-living, benthopelagic copepod species Pseudocyclops xiphophorus Wells (R Soc Edimburg 67:1967), collected over a yearly cycle from the fouling material in the brackish water Lake Faro (North-eastern Sicily), showed marked seasonal fluctuations in population abundances, with maximum numbers recorded in autumn. Highest in situ egg production rates coincided with periods of low adult and juvenile densities and vice versa, except in autumn when peaks in egg production and adult population densities were coincident. In this period, mean daily egg production rates reached a maximum of 4–5 eggs per female, when surface water temperature was 17–18°C. Egg production rates declined drastically in winter and were completely arrested when surface temperatures dropped to 10–12°C. In March, daily egg production rates began to increase again with an increase in ambient temperatures, reaching a maximum at the end of August. In the laboratory, as in the field, mean daily egg production rates were positively correlated with temperature, with values ranging from 2.2 ± 0.3 (16°C) to 8.9 ± 2.6 (30°C) (mean ± S.D.) eggs per female per day. At 32°C, P. xiphophorus females survived but did not reproduce. At 34°C, all specimens died after a few days. In terms of total egg production for the entire female lifespan, maximum values occurred at 16°C and minimum at 24°C. Temperature also dramatically affected female life span, which was shorter at higher temperatures. Development time of eggs decreased with increasing temperature, as also development time from egg to adulthood. Remating was necessary for the continued production of fertile eggs at 16°C because female life span was longer. The unique egg-laying behaviour in this species may ensure higher survival rates of egg stages compared to free-spawning and egg-carrying calanoid species. After releasing the egg pair, the female swims over the eggs with a rotatory motion, secreting a substance which facilitates the adhesion of the eggs to the bottom; she then continues to swim over the eggs until they are attached. Although egg production rates in this species are low compared to other pelagic copepods, they are within the range of values reported for egg-carrying species. The greater fecundity at higher temperatures compared to other subtemperate species indicates that the species is well adapted to the higher temperatures of coastal lagoons and brackish water lakes where it contributes to the biofouling community.

Average abundance values for Euphausia crystallorophias in the shelf region of Terra Nova Bay were generally high. Mean number of adults and juveniles were 20 and 87 ind/m2, respectively, while larval concentrations were much higher, reaching a mean of 14,764 ind/m2. Euphausia crystallorophias were very patchy in their distribution during all stages of their life cycle. The distribution patterns of E. crystallorophias in TNB seem to be strictly correlated both to hydrological features such as the presence of polynyas, pack-ice zone and certain temperatures values. According to our data, E. crystallorophias spawned from early October to early January. For the two age groups (0+ and 1+) an average growth rate of 0.074 and 0.076 mm/day was found, respectively. The mean biomass of larval E. crystallorophias (from Metanauplius to Furcilia I) in January was estimated as 84 mg WW/m2.

Egg production, hatching success and naupliar survival were determined for Pseudocyclops xiphophorus pairs fed a Skeletonema marinoi, a flagellate (Tetraselmis suecica, Pavlova lutheri and Isochrysis galbana) and a mixed (Skeletonema and flagellates) diet. Pairs fed Skeletonema marinoi showed significantly lower egg production and naupliar survival than couples fed flagellates and mixed diet. But hatching success was more or less similar with the three food types. Furthermore, feeding experiments demonstrated a clear preference of P. xiphophorus for the flagellate food type.

The feeding habits of the mesopelagic lanternfish Electrona risso from the Strait of Messina (central Mediterranean Sea) were analyzed for the first time. A total of 326 individuals were collected stranded along the Sicilian coast of the Strait of Messina from October 2012 to May 2013. Specimens ranged from 12.0 to 53.8 mm L S (mean L S = 38.6 ± 8.4 mm). Their stomach content was examined and prey composition and feeding strategy were investigated. The results indicate that E. risso is a specialist predator, which feeds mainly on the small mesopelagic fish Cyclothone braueri (% IRI = 74.06) and in minor proportion on zooplankton, with a prevalence of copepods. The specialized feeding strategy of E. risso is confirmed by the low value of Levins standardized index ( B j = 0.141), which indicated a restricted niche breadth. The value of the index of trophic level ( TROPH ) for E. risso resulted 4.20. The prey composition suggests that E. risso can be considered a weakly vertical migrating species, that feeds on the DSL crustacean and fish communities below 300 m of depth.

The aim of this study was to investigate patterns of abundance, distribution, temporal changes and species composition of the dominant ice-associated copepods in the spring annual pack ice, platelet ice and water column at Terra Nova Bay, Ross Sea, during late spring 1997. Ice cores were drilled for temporal and spatial scales. Stephos longipes and Harpacticus furcifer dominated the sea ice meiofauna in terms of numbers in the lower few centimeters of the bottom ice associated with high chlorophyll a and phaeopigment levels. Nauplii dominated the S. longipes population (91.6%) and occurred in extremely high concentrations. In contrast, copepodids were the dominant stages in H. furcifer. How H. furcifer carries out its entire life cycle and how it differs from ecologically similar species such as Drescheriella glacialis should be examined in more detail.

Field and laboratory studies were carried out on the bentho-planktonic species P. xiphophorus Wells, 1967. This species was found in the Mediterranean Sea, in the brackish Lake Faro (north-eastern Sicily) for the first time. Specimens of P. xiphophorus were collected from November 2003 to September 2004. Immediately after sampling, all adult females were sorted and pipetted individually into 50 ml crystallizing dishes containing lake water and incubated at the same enviromental temperature, measured at the sampling time. After 24 h, the number of eggs produced by each female was counted to estimate in situ egg production rate. In the laboratory, groups of five couples of males and females were placed individually into 50 ml crystallizing dishes containing filtered sea water enriched with three phytoplankton species, Tetraselmis suecica, Pavlova lutheri, and Isochrysis galbana, given in excess concentrations. Groups of five replicates were incubated at three different temperatures, 16, 24, and 28 °C, for e...

The bentho-planktonic calanoid copepod Pseudocyclops xiphophorus Wells, 1967, previously recorded only in coastal waters of Mozambique, has been found in the brackish Lake Faro (eastern Sicily, central Mediterranean). The copepods were collected from fouling attached to submerged mooring posts and ropes in the Lake. Both sexes of P. xiphophorus are redescribed. This interesting zoogeographic distribution suggests that the Mozambican and Mediterranean Pseudocyclops populations exhibit a complete Tethyan pattern.

The authors describe the six naupliar and five copepodid stages of Pseudocyclops umbraticus raised in the laboratory. These are the first data on the ontogenetic stages of a species of the genus Pseudocyclops. On the basis of these results and the adult morphology (Giesbrecht, 1893), the authors place P. umbraticus in an intermediate position between the lepidotus-kulai and crassiremismagnus groups of Ohtsuka et al. (1999).

The Mediterranean Sea is one of the areas most affected by alien invasions, which are continuously increasing also due to intense human activities and environmental changes that favor the introduction of species previously unable to colonize the basin. This is the case of the copepods of the genus Pseudodiaptomus, first described in the Indian Ocean and considered one of the most resistant to unfavorable conditions but never recorded in the Mediterranean until 2011 though present in adjacent seas. Pseudodiaptomus marinus, in particular, is common in shallow marine-brackish waters and is one of the species often found in ballast waters and in aquaculture plants. Native of Japan, it has started spreading since 1950s and its populations have established in several harbours, eutrophic inlets and lagoons along the coasts of the Pacific and Indian Oceans. In the last few years, P. marinus has been increasingly reported in European Seas (Mediterranean Sea and North Sea). In this paper, we review the invasion history of this species with a special emphasis on its records in the Mediterranean Sea, and its occurrence and establishment in Sicilian waters. We also compare the biological traits and population dynamics of P. marinus with those of other representative of the genus and discuss about the possible mechanisms of introduction in new environments. Aim of our work is to understand the reasons of successful invasion of P. marinus and the environmental and biological factors that may lead to its further biogeographic expansion.

Six naupliar stages are described based on specimens of Stephos longipes Giesbrecht, 1902, obtained from sea ice near Terra Nova Bay, Antarctica. Marked differences between nauplii of Stephos longipes and Paralabidocera antarctica (I. C. Thompson, 1898) were used only to identify the two species in the samples. The copepods Stephos longipes and Harpacticus furcifer Giesbrecht, 1902, accounted for more than 90% of sympagic communities in the annual sea ice at Terra Nova Bay.

Two oceanographic cruises were carried out in the northern Adriatic Sea, from June, 1996 to February, 1997. Samples were collected using a BIONESS electronic multinet (204 samples on 54 stations) along inshore-offshore sections. Zooplankton abundance and biomass were estimated in relation to the variability of temperature, salinity and fluorescence. Spatial and vertical distribution patterns of the most important zooplankton groups were studied. During June, in the northern area, abundance and biomass of 2787 - 1735 r ind m and 29.3 - 26.7 r mg r m, respectively, were reported. The zooplankton community was constituted essentially by copepods and cladocerans. In the southern area, instead, an abundance of 4698 - 5978 r ind r m and a dry weight of 25.4 - 15.3 r mg r m were observed, with a reverse dominance ratio between these groups. In February, in the northern area the zooplankton community (1380 - 595 r ind r m and 19.6 - 9.9 r mg r m) was mainly constituted by copepods, larvae of invertebrates, append...

Stephos cryptospinosus sp. nov., a new species of calanoid copepod, is described from Western Mediterranean coastal waters. It differs from other species of the genus in the structure of the fifth legs in both sexes, and in having a small spinous process on the posterolateral margins of the last prosomite in both sexes.

Mesozooplankton plays a role in particulate organic carbon (POC) remineralisation from the pelagic sinking POC flux down the water column. The vertical distribution (to 1000 m depth), diel variability (during a 24 h cycle) and seasonal differences of the mesozooplankton carbon requirement (µg C g �1 d �1 ), estimated by measuring the activity of the electron transport system, were investigated at a fixed station in the southern Adriatic Sea during November 2006 and April 2007. To estimate the quantitative role of zooplankton in the carbon loss that occurs during organic particle sinking, the zooplankton carbon requirement was compared with organic carbon vertical fluxes measured using a sediment trap. Zooplankton abundance, biomass and community composition were investigated along with the diel vertical distribution of euphausiid migrating groups and the relative importance of crustaceans and gelatinous taxa to the potential community carbon requirement. Day/night zooplankton carbon requirement differences in the upper 100 m were shown in both sampling periods. They were not at all correlated to the vertical distribution pattern of euphausiids but were attributable to the amount of non-living specimens and/or the ratio between gelatinous and crustacean taxa. The mean metabolic requirement in the sampled layers of the water column was lower in November than in April, ranging from 0.02 to 9.10% and from 0.07 to 31.86%, respectively, of the measured carbon losses. In the epi- and meso- pelagic zones, the total percent contributions of mesozooplankton respiration to organic carbon losses were 0.18 and 18.45%, respectively, in November and 1.41 and 87.27%, respectively, in April. The higher remineralisation percentages detected in April compared to November could be linked to seasonal differences that involve higher primary production, zooplankton biomass, ver- tical amount of sinking POC flux and more intense heterotrophic metabolism, which take place mainly in the meso pelagic layer in each period.

The calanoid copepod Pseudodiaptomus marinus Sato, 1913 is an estuarine-coastal species, living in shallow eutrophic inshore waters. It is native of the Indo-Pacific region, but in the last 50 years, it has successfully colonized new areas worldwide. P. marinus, first recorded in Lake Faro (Messina, Italy) in October 2008, is now a stable component of the zooplankton assemblage of the lake. By means of video recordings, for the first time, the swimming behaviour of males and non-ovigerous and ovigerous females of P. marinus has been studied. The individuals were filmed in the presence and absence of food to evaluate how the presence of prey might affect the swimming behaviour. The swimming motion showed marked sex-dependent features and responses to the presence of food. Mechanisms through which behaviour might influence the outcome of a new colonization were analysed. The behaviour of P. marinus was then compared with that of the congeneric Pseudodiaptomus annandalei showing the typical behaviour displayed by the representatives of the genus Pseudodiaptomus of living in proximity of the bottom. Environmental and hydrological conditions in Lake Faro have likely provided the newly introduced P. marinus a suitable environment for settling, although normally the presence of an anoxic deep layer would be detrimental for a demersal species. In this case, the plasticity in the behaviour of P. marinus enhanced its capacity for colonising new environments. Switching from demersal to pelagic habitat or being fully planktonic allowed it to express its large individual variability in motion strategies and thus to successfully colonize the lake.

Two new species of asterocherid associated with sponges are described from the Mediterranean Sea. They are Psilomyzon laetitiae sp. nov. and Psilomyzon sarcotragusicola sp. nov. The genus Psilomyzon consists of only one known species, P. pauciseta. The two new species can be easily distinguished from the cogener species by reduction of the endopod of leg 4. In P. pauciseta the leg 4 endopod is 3-segmented, with the third segment reduced; in both new species it is 2-segmented, with the second segment carrying an inner projection, possibly homologous to the third segment of the leg 4 endopod of P. pauciseta. In the two new species, the bifid outer process on male leg 4 second endopodal segment seems to be serially homologous to the similar processes on the same segment in legs 1–3, whereas the inner projection may represent a vestigial element of the third endopodal segment of leg 4.http://zoobank.org/urn:lsid:zoobank.org:pub:33BF0653-BBA9-426B-B365-5D8C62DFD44A

Spring vertical distribution of copepod communities was studied every 6 h during a 24 h cycle, using the BIONESS multinet, to evaluate diel vertical migration (DVM) of the key species in a Central Tyrrhenian Sea station (from 0 to 2000 m). Similar abundance trends were detected for the four sampling times. Highest abundances were recorded between 20–40 and 60–80 m depth, at midnight and in the morning. In epipelagic layers, highest diversity occurred between 20 and 100 m in the morning and at midday, and from 100–200 m in the afternoon and 300–400 m at midnight, in mesopelagic ones. DVM involved mostly the 60 and 300 m depth interval. Epipelagic and mesopelagic copepods co-occurred in this stratum, so diel changes in species composition and diversity induced shifts in the slope of the highest k-dominance curves. The epipelagic Neocalanus gracilis and the intermediate Eucalanus elongatus copepod species showed a bimodal distribution. Only the shallower population of E. elongatus exhibited significant DVM. Few other copepod species showed significant DVM (the epipelagic Scolecithricella dentata and the subsurface Corycaeus furcifer and Pleuromamma gracilis ), confirming previous information about the presence of few strong migrants in the Mediterranean Sea. Lucicutia longiserrata , Gaetanus kruppi and Monacilla typica with their copepodites were the only species dominant below 600 m depth and they were not affected by DVM.

Spatial and temporal variability in zooplankton was studied at eight stations located in the Lesina Lagoon (South Adriatic Sea) Salinity, temperature, dissolved oxygen and chlorophyll a (in the lagoon)at these stations were also assessed. The zooplankton community was characterised by clear seasonal oscillations and mostly represented by copepods and their larvae. The dominant copepod species were Calanipeda aquaedulcis and Acartia tonsa, which exhibited spatial-temporal segregation in the lagoon. C. aquaedulcis copepodites seemed to be better adapted to oligotrophic and oligohaline conditions compared with the A. tonsa population. The invasive species A. tonsa has completely replaced the formerly abundant Acartia margalefi. A positive correlation was found between abundances, total species numbers and trophic state. An increasing abundance trend was shown from the lagoon towards the sea. The highest diversity indices were recorded at the two channel inlets, during high tide due to the absence of a clear dominance of one or more coastal species and the co-occurrence of species of lagoon and marine origin.

International audience

Biogeographia vol. XXI V - 2003 (Printed October, 3131‘ 2003) Marine biogeography of the Mediterranean Sea: patterns and dynamics of biodiversity Mediterranean calanoid copepods biogeography: new species identification and first records of hyperbenthic forms GIACOMO ZAGAMI, 1\/LARINA CAMPOLMI, ANTONIA GRANATA Dz'pzzrtz'mmt0 zli Biologizz Azzimzzle ed Ecologizl Mzzrmzz, Unit/ersitfz di Messinzz, Szzlitzz Sperone, 3], 1—98]66, Messimz (Italy) Keywords: Calanoid copepods, plankton, hyperbenthos, biogeography, Mediterranean Sea, biodiversity. SUMMARY The spatio-temporal distribution patterns of the Mediterranean planktonic and hyperbenthic calanoid copepods were analysed. The atlantic origin 0F the major part ofplanlttonic calanoid copepods was defined, distinguishing between Mediterranean own species and the Alboran Sea, and Levantine Bacin populations migrated, rispectively, From Atlantic and Indo—Pacific Oceans. In the Mediterranean the presence, as other oceans of the world. of a hyperbenthic specific calanoid copepods community was showed. In this “ecological group” were identified populations ofatlantic and indo- pacific origin. of recent and ancient migration in the Mediterranean. lNTRODUCTION Copepoda, a subclass of the phylum Crustacea, consists of ten orders: Platycopioida, Calanoida, Misophrioida, Mormonilloida, Cyclopoida, Geliyelloida, Harpacticoida, Poecilostomatoida, Siphonostomatoida and Monstrilloida. Copepods are aquatic, mainly marine, organisms that have spread by adaptive radiation into all habitats, including the ocean depths, brackish coastal lagoons, submarine caves, and fresh waters of high mountain rivers and lakes. Humes (1994) estimated that by the end of 1993 about 11,500 species of Copepoda had been identified. Excluding Diaptomidae, around 1800 species of Copepoda Calanoida have been censused in the marine ecosystem (Huys and Boxshall, 1991; Humes, 1994). In their inventory of Mediterranean planktonic Copepoda, Razouls and Durand (1991) listed 301 species of Calanoida, to which must be added 11 new species identified between 1991 and 2000 for a total of312 species. There are records of 173 species of Copepoda Calanoida in Italian seas (Argano et al., 1995), i.e. 55.8% of the total identified in the Mediterranean. Since there

Within the framework of the Prisma 2 Project, four oceanographic cruises were carried out in the central and northern Adriatic Sea from June 1996 to March 1997. Samples were collected both by BIONESS electronic multinet (204 samples from 54 sites) and by WP2 (101 samples from 19 sites) along inshore-offshore sections. The spatial-temporal distribution of the zooplankton community was analysed in relation to the variability of physico-chemical and biological parameters. The seasonal succession of the zooplankton community was characterized by an inversion of the dominance ratio between copepods and cladocerans. In early June, copepods and cladocerans represent on average 52 and 20% of the zooplankton community, respectively, while in late summer they represent 17 and 66%. During late spring-summer, the cladoceran population was clearly dominated by Penilia avirotris, which in some coastal sites constituted more than 90% of the zooplankton. In the coastal zone, the copepod population was characterized by low species diversity and greater dominance of A. clausi, P. parvus and T. stylifera (73% of the population). In the offshore zone of the neritic system, there was instead a more homogeneous copepod species composition. Because of their spatial distribution patterns, P. elongatus and T. longicornis, typical of estuarine environments,can be considered as hydrological indicator species of different water masses of the Adriatic neritic system. In winter, the zooplankton community was characterized by strong dominance of copepods (31 species identified), on average constituting 75% of the zooplankton, followed by invertebrate larvae, appendicularians, cladocerans, siphonophores and chaetognaths. From our analysis of the spatial distribution of the zooplankton community, we have formulated a preliminary trophic model concerning the association of ecologically similar species in the water masses of the Adriatic neritic system.

During the summer Italian Antarctic Expeditions of 1987–88 (Polar Queen cruise) and 1989–90 (Cariboo cruise), mysids were collected in Terra Nova Bay and the western Ross Sea (268 and 572 samples, respectively), by a multinet BIONESS. Four species (Boreomysis brucei, Caesaromysis hispida, Dactylabblyops hogdsoni and Euchaetomera zurstasseni) were caught in the Pacific sector of the Southern Ocean and western Ross Sea while Antarctomysis ohlini was the only species found in Terra Nova Bay. It reached maximum densities in the southern part of the bay in deep straits and trenches. The absence of Antarctomysis maxima in both BIONESS samples and in the gut contents of coastal benthic fishes suggests that A. maxima inhabited the outer shelf of Terra Nova Bay, while A. ohlini was confined in the deeper trenches of the bay. The generation time from egg to egg for A. ohlini in Terra Nova Bay was assumed to be 5 years. The growth rate of juveniles was estimated to be about 1 mm per month and the newly moulted young CO caught at Terra Nova Bay in January were about 3 months old. Gut content analysis confirms that A. ohlini was a generalist during its life cycle. Diatoms were the most important group in the juvenile diet composition. The ice-algae Fragilariopsis curta dominate the diatom assemblages in all samples. Coprophagy seems to be the principal feeding in juveniles (age 0 and age 1+), whereas diet diversity increased with increasing size in the species.

During four spring-summer Italian Antarctic expeditions to Terra Nova Bay and the Western Ross Sea in 1988, 1989–90, 1994–95 and 1996, zooplankton and ichtyoplankton were collected by a multinet BIONESS (250 μm and 500 μm) and PHN (500 μm), respectively. Nototheniids were predominant in the whole study area, representing 97.3% of all larvae. Pleuragramma antarcticum was the dominant species sampled in the spring-summer cruises of 1987–88 (98.6%), 1989–90 (95.9%) and 1995–96 (99.8%), while it predominated in association with Trematomus lepidorhinus in 1994–95. The early life history of Pleuragramma antarcticum was described from 891 samples. Maximum abundances of P. antarcticum postlarvae were confined to Terra Nova Bay. The mean relative abundance in the whole area in summer 1988, for positive 0- to 150-m hauls, was 434 (±720 SD) specimens 100 m−3 and 158 (±212 SD) specimens per 100 m3 in January 1990 for positive 0-140-m hauls. Off Terra Nova Bay, postlarval abundance did not exceed 5-86 individuals 100 m−3. Juvenile Pleuragramma antarcticum showed a more oceanic occurrence than postlarvae of the same species. Low concentrations between 0.1 and 12.5 ind 100 m−3 (mean 1.66 ± 2.88 SD) were recorded in offshore waters between 170° and 175°E and in the southern part of Terra Nova Bay. Postlarvae (n = 4385) ranged between 7 and 23 mm SL (mean 13.9 ± 1.62 SD) and juveniles (n = 388) were between 28 and 53 mm SL (mean 40.0 ± 4.78 SD). A growth rate of 0.08 mm day−1 was confirmed for the first year. The daily increments of Pleuragramma antarcticum postlarvae estimated from sequential sampling in 1987–88 from Terra Nova Bay and in 1995–96 from the southern western Ross Sea were about 0.21–0.25 mm. The co-occurrence of different postlarval size classes during the investigations confirm that two hatching periods occurred in Terra Nova Bay between early and late December. The presence of early stages in January 1988, 1990 and 1996 (7–9 mm SL) confirms that Pleuragramma antarcticum spawn in Terra Nova Bay. Highest concentrations of postlarvae occurred at the edge near Cape Washington and in the inshore waters of Drygalski Ice Tongue. These areas seem to represent a nursery ground of early stages, where the presence of permanent polynyas could provide favourable food conditions for the development of the first stages of life. More than 62% of the postlarvae were collected in well-stratified Antarctic Surface Waters (AASW) with temperature values that exceed 0°C and vertical distribution appears to be related to the summertime thermocline. From these sites, early stages were drifted by a westward-flowing current of the limb of the Antarctic coastal current and the southern limb of the Ross Sea Gyre. These large gyres favoured postlarval retention mostly in northern and southern areas of Terra Nova Bay, preventing the drift north of Cape Washington, south of Drygalski Ice Tongue and in offshore waters beyond 170°E. Thus, the youngest planktonic stages of Pleuragramma antarcticum concentrate in the surface mixed layer of Terra Nova Bay where feeding conditions are favourable. In the size classes 8-17 mm the diet was dominated by calanoid eggs (35.5%), Limacina (32.1%) and tintinnids (17.6%). The cyclopoid copepod Oncaea curvata contributed to 7.1% of the diet.

In situ rates of egg production and hatching success are reported for Calanus simillimus, one of the most abundant calanoid species in peri-Antarctic regions, during the Italian ‘Italics’ cruise in the Straits of Magellan in March-April 1995. Low fecundity (8.6 eggs female −1 day −1 ) and fecal pellet production (0.8 fecal pellets female −1 day −1 ) in this period indicate that the species was feeding very poorly. Sixty-six of the 126 females sampled did not produce eggs and 80 of these did not produce any fecal pellets during the 24 h period of incubation. Striking abnormal naupliar and embryonic development was recorded in 81.8% of the eggs spawned. Aberrant eggs did not undergo normal cleavage, and failed to develop to hatching. Deformed nauplii were asymmetrical and presented strong anatomical anomalies in the total body length and number of swimming appendages. These results are discussed in the light of recent findings on the causes of low hatching success in copepods.