Observations on colony formation by the cosmopolitan phytoplankton genus Phaeocystis

Few marine phytoplankton have heteromorphic life cycles and also often dominate the ecosystems in which they occur. The class Prymnesiophyceae contains a notable exception: the genus Phaeocystis includes three species that form gelatinous colonies but also occur within their ranges as solitary cells. Phaeocystis antarctica and P. pouchetii are exclusively high latitude taxa, and are notable for regionally tremendous blooms of the colony stage. P. globosa occurs circumglobally, yet its colony blooms primarily are confined to colder waters within its range. Three additional species are warm water forms that have been reported only as solitary cells or loose aggregations that bear little resemblance to the organized colonies of the other taxa. Interpretation of existing data indicates that resource availability (light, temperature and nutrients) by itself is not sufficient to explain this distinction between cold-water colony-forming taxa and warm water solitary cell taxa, nor why colony development in P. globosa is essentially a spatially restricted phenomenon within a much broader geographic range. Colony development by P. globosa in situ has been observed at temperatures ≥20 °C, but only rarely and generally under conditions of seasonally or anthropogenically elevated nutrient supply. Data presented here demonstrate colony development at 20–22 °C in natural plankton communities from oligotrophic waters that were pre-screened through 63 μm mesh (i.e. lacking mesozooplankton and large microzooplankton), but not in unscreened communities containing microzooplankton and >63 μm zooplankton. Reduction of colony proliferation at higher temperatures by mesozooplankton grazing remains as an intriguing possibility that is consistent with available evidence to help explain differences in latitudinal extent of in situ colony development. These data are interpreted within a theoretical framework regarding the potential advantages and disadvantages of the two life cycle stages.     

Distribution, reproduction and development of Calanus species in the Northeast water in relation to environmental conditions

The vertical and horizontal distribution of mesozooplankton biomass and its composition, together with the reproduction and development of the three dominant herbivorous copepods Calanus finmarchicus, C. glacialis and C. hyperboreus, were studied in the Northeast Water between the end of May and end of July, 1993. Biomass varied between 0.15 and 10.6 g m⁻² and was lower on the shallow banks. Highest biomass was found on the shelf slope and in the entrances to Belgica and Westwind Troughs. There was no seasonal trend during the study period. Among the zooplankton taxa, copepods were dominant, with 84% biomass of all other taxa, followed by chaetognaths with 14%. The large Calanus species made up 91% of copepod biomass. The most abundant species, C. glacialis, inhabited areas of low current speeds on Belgica and Ob Bank, C. hyperboreus dominated shelf slope and trough stations, while C. finmarchicus was most abundant in the Return Atlantic Current along the shelf slope and also eastern Belgica Trough. C. glacialis was the only Calanus species spawning during this period, but young copepodites of the other species were also abundant. Egg production of C. glacialis was at a maximum by our arrival and continued to at least mid August. According to the results from starvation experiments, its egg production was fuelled by food uptake, but was decoupled from phytoplankton chlorophyll until July, indicating ice-algae and microzooplankton as an alternative food source. Only when the polynya approached its maximum extent was a close relationship to phytoplankton established. Due to both spatial and temporal heterogeneity of the occurrence of young copepodite stages it was impossible to follow the growth of cohorts of developmental stages. Herbivorous carbon requirements estimated from egg production rates were mostly less than one third of the phytoplankton stock. From egg production and the distribution of young stages, the outer Westwing Trough seems to be the centre of biological activities. This may be related to the formation of young ice in winter in this area, which was found to carry a large mass of under-ice algae. High biomass but low production in Belgica Trough indicate this as an advective and expatriated community of C. finmarchicus and C. hyperboreus, where grazing is negligible, at least during early summer.     

International trade in marine species: Is CITES a useful control mechanism?

Abstract

The Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) was created to prevent species becoming threatened through international trade. It generally prohibits international commercial trade in seriously threatened species but permits trade in a regulated manner in species vulnerable to exploitation but not yet at risk of extinction. CITES covers comparatively few marine taxa, reflecting the fact that most marine species have much greater ranges and fecundity than terrestrial species and so are more resilient to exploitation. Exceptions are to be found in the higher vertebrates. Several marine mammals may have benefited from CITES controls, although their popular appeal, commercial importance, and extreme vulnerability have meant that other treaties and conservation activities have been adopted to control their exploitation. Marine turtles Cheloniidae and the estuarine crocodile (Crocodylus porosus) certainly have benefited from CITES controls. Many commercially important fishes and invertebrates are covered by international and regional fishery agreements; a few, with life histories making them particularly vulnerable to exploitation, are subject to CITES controls. The structure of CITES limits its utility as a conservation tool for marine species, but where other mechanisms fail or are absent, it plays a useful role, and it is particularly valuable as an international trade monitoring mechanism.     

The coastal edge of the Northeast Water polynya in spring 1993

Multidisciplinary, marine ecological observations were conducted at the shallow water edge of the Northeast Water in June, 1993. Although variable in size and shape, a small polynya was constantly present at Eskimonaes, at the fast-ice edge of Ingolfsfjord. A shallow stratified layer developed at the water sufface at negative water and air temperatures—an effect of sea ice melting in cold water early in the season. Nutrients were recorded in considerable quantities, although by mid July NO₃ had become depleted. The chlorophyll and phytoplankton maxima at 8–12 m depth had peak values of 2 mg chl a m⁻³, typical for Arctic algal blooms. The phytoplankton included over 90 species and was dominated by the Fragillariopsis group. Zooplankton was poor in biomass and density, but over 23 taxa were found, with the copepods Oithona similis and Pseudocalanus acuspes being numerically dominant. Sedimentation was approximately 0.2 g dry weight m⁻² d⁻¹ and suspended matter concentrations ranged from 4 to 19 mg l⁻¹. The benthos was represented by hard bottom forms only, with a surprisingly dense cover of macrophytes. Juvenile sea urchins (Strongylocentrotus droebachiensis), brittle stars (Ophiocten sericeum) and amphipods were dominant. Higher trophic levels were represented by benthic feeders, such as eiders and walruses. The area observed was more similar to high Arctic fjord ecosystems than to the offshore central Northeast Water polynya.     

Port competition in Latin America and the Caribbean: the role of concessions and competition policy

Appropriate port regulation and competitive forces tend to be related to higher levels of operational and economic performance of ports. From a policy-making perspective, pursuing efficiency and securing competition in ports to reach a level playing field is a two-step process requiring (1) ex-ante regulations to set the rules that maximize the competition for the market, especially when the policy objective is to attract private operations to ports on competitive concession processes and (2) ex-post competition policy to monitor and preserve competition in the market. This paper studies port regulation in Latin America and the Caribbean (LAC) from a competition perspective, analyzing both ex-ante and ex-post policies implemented in the region. The analysis reveals that the competitive environment in LAC is low, giving room for possible anticompetitive practices in the LAC port sector. Since the end of the 1990s, approximately 80% of container terminals in the region were granted to only five companies. Chile and Mexico have been found to be the best practices in the region, with better conditions assuring robust competition in the market. The main policy implication from this analysis is the need for a stronger involvement of antitrust agencies throughout the port concession processes.     

Distribution of plankton lipids and their role in the biological transformation of Antarctic primary production

Production and transfer of lipid through the Antarctic food web is reviewed for the Indian Ocean sector. The slow settling fine particles showed a marked inter-annual variability in biochemical composition with an increase in lipid content as % organic carbon. Comparison of the fatty acid spectra of different size categories of organic particles indicated that fine particles are dominated by saturated, monoenoic and branched acids, while larger material (50–100 μm, 200–500 μm net collected fractions) displayed a signature dominated by polyunsaturated acids. Zooplankton taxa displayed different strategies of lipid accumulation. Lipid content was highest in Thysanoessa macrura females and copepodite stages of Calanus propinquus. Relatively low levels were recorded for juveniles and male stages of euphausiids. Reserve lipids varied with species: C. propinquus showed equal content of triglycerides and wax esters, T. macrura showed a dominance of wax esters and Euphausia superba and Themisto gaudichaudii accumulated only triglycerides. Computed as carbon equivalent and integrated over 200 m, lipids in slow settling particles represented 22.6% of annual primary production. Similar computation with mesozooplankton and E. superba data on biomass and population structure from several summer cruises indicated values of carbon accumulation as lipid reserves and egg production of 4.2 and 0.1% of annual primary production for copepods and 4.4 and 3.8% for E. superba. When all trophic levels are considered, the overall mean exceeded 30% of annual primary production.     

Seasonal carbon distribution of copepods in the eastern Weddell Sea, Antarctica

Copepods were sampled by a multiple opening-closing net in the eastern Weddell Sea during various seasons (late winter/early spring, summer, autumn). Total copepod biomass integrated over the upper 1000 m varied seasonally between 1.7 mg C m⁻³ in late winter/early spring and 3.7 mg C m⁻³ in autumn. After the dark season the copepods were rather evenly distributed vertically and highest biomass levels were found in the mid-water layers between about 200 m and 500 m. By contrast, especially in summer but also in autumn copepod biomass concentrated in the uppermost water layer. A total of 64 calanoid species were identified in the upper 1000 m with maximum species numbers in the deepest layer. The large calanoids Calanus propinquus, Calanoides acutus, Metridia gerlachei, Euchaeta antarctica and the small calanoid Microcalanus pygmaeus prevailed and accounted for 60–70% of total copepod biomass, while the small poecilostomatoid Oncaea and the cyclopoid Oithona species comprised about 20%. Hence, the distribution pattern of the entire copepod biomass is strongly influenced by the life cycles of a few dominant species.     

Harpacticoid and cyclopoid fauna of groundwater and springs in southern Finland

The groundwater fauna, of which scarcely anything has previously been studied in formerly glaciated areas, was richest close to the water table and diminished markedly at greater depths. However, few individuals were generally recorded per 1 m³ of water. Bryocamptus minutus was the most abundant species of copepod at an esker site, the other species recorded beingAttheyella crassa, Bryocamptus pygmaeus, Moraria brevipes and Parastenocaris phyllura, and some species from the genus Diacyclops. At a shore bank infiltration site M. brevipes was the most numerous species. However, one esker site examined did not have any animals. Springs, which were grouped into those in a natural state and those under anthropogenic influence, had some species in common with esker groundwater, but also Paracyclops fimbriatus, Acanthocyclops robustus, Acanthocyclops vernalis, Diacyclops bicuspidatus, Megacyclops viridis, and the harpacticoid species Bryocamptus cuspidatus, Bryocamptus echinatus and Canthocamptus staphylinus. Of the spring copepods, P. fimbriatus appeared to withstand the influence of road de-icing with NaCl, but numbers of Moraria brevipes were reduced under this influence. Bryocamptus echinatus was more numerous in springs having a high oxygen content and high pH. The species found in esker groundwaters and springs were in part the same evidently cold-stenotherm species which inhabit the profundal zone of oligotrophic lakes.     

Benthic foraminifera in the surface sediments of the Beaufort Shelf and slope, Beaufort Sea, Canada: Applications and implications for past sea-ice conditions

This paper presents new data on distribution patterns of modern benthic foraminifera and other microfossils from the Canadian Arctic, specifically the Beaufort Shelf and slope. The material was collected in June to August of 2004 and is the first of its kind in this area to be collected since 1970. We examined the smaller sizes (45–63µm) as well as > 63µm and discovered that many species had been severely underrepresented in previous studies. Deep sea forms, that had been overlooked previously, were common on the shelf; two species (Elphidiella arctica and Ammotium cassis) appeared in preliminary results to be indicators of methane seepage; and it was possible to make determinations of sea-ice coverage using a combination of foraminifera and tintinnids (planktic ciliates). Our data indicated the presence of many of the same species as previous studies from this area, but improved techniques of sample processing greatly increased the number of specimens and species found (particularly the small deep sea arctic species Buliminella hensoni and Bolivina arctica) which provide much more reliable data for paleoceanographic determinations. One of the primary objectives for this work was to provide baseline data to help determine paleo-ice cover; these data cover a broad range of conditions on the Beaufort Shelf that make it possible to achieve this objective as well as improving what it is known about the assemblages on this shelf as compared to other arctic shelf areas, such as the Siberian Shelf).     

Annual cycle of distribution of three ice-associated copepods along the coast near Dumont d'Urville, Terre Adélie (Antarctica)

In polar regions sea ice is a site of enhanced primary production during winter and provides important habitat for small grazers, such as copepods. We sampled zooplankton from the sea ice and water column throughout 2005, near Dumont d'Urville station (Terre Adélie, Antarctica). Three species of ice-associated copepods were found: two calanoid copepods Paralabidocera antarctica and Stephos longipes and the harpacticoid copepod Drescheriella glacialis. P. antarctica was the most abundant of the three and was closely associated with the sea ice during most of the year. This species had a one year life cycle with a probable over-wintering period in the sea ice as nauplii and a short copepodite phase in spring. Reproduction and spawning occurred in early summer. A comparison with two other populations (near Syowa and Davis stations) along the east coast of Antarctica showed that there was a temporal shift in the life cycles of the three populations, which was linked to variability in sea ice conditions. D. glacialis was the second most abundant copepod and was more common during the winter than during summer, indicating its preference for the sea ice habitat. In autumn, the presence of D. glacialis in the deeper part of the water column suggested that this species colonised the sea ice from the benthos. S. longipes was found only in the water column near Dumont d'Urville and was not very abundant. In Terre Adélie particular environmental conditions, such as the absence of a permanent sea ice zone throughout the year, a longer time of open water, strong katabatic winds and the presence of polynyas, have influenced both the abundance and distribution of the three common ice-associated copepods.     

Spatio-temporal variations in deep-sea demersal communities off the Balearic Islands (western Mediterranean)

The spatial and temporal variations of deep-sea megafaunal assemblages from the western Mediterranean are analysed in the present paper. The assemblages from two locations of the Balearic Islands situated 120 km apart were compared using data collected seasonally on a bathymetric stratum covering the 150–750 m depth range during six bottom-trawl surveys. The assemblage structure, in terms of species composition, species dominance and population sizes, was differentially affected by the spatio-temporal variables analysed (depth, location and fishing period). Although depth was the main factor determining the assemblage composition, the differences obtained between the two locations were also relevant. On the upper slope these between-location differences in the dynamics of megafaunal assemblages were found to be related to the effect of fishing exploitation. Population size-based metrics and biomass spectra were good predictors of meso-scale fishing effects, and were mainly reflected by elasmobranchs and demersal teleosts. Nevertheless, the effects of fishing depended on the species considered. Two dominant large-sized fish species found on the upper slope in both localities, Galeus melastomus and Phycis blennoides, had higher biomass values associated with lower fishing effort. Although the mean body weight (MBW) of both species and also the mean maximum body weight (MMBW) of G. melastomus agreed with this pattern, the P. blennoides MMBW did not. This last case could be indicative of natural size-trends such as the bigger–deeper phenomenon which refers to the displacement of large individuals towards the deeper limit of their bathymetric distribution, beyond the maximum depth sampled in this study for this species. By contrast, the target species of the upper slope fishery, the red shrimp Aristeus antennatus, was not negatively affected by the direct impact of fishing activity and other environmental factors, such as the presence of specific water masses could also be important.     

Distribution of dinoflagellate cysts in surface sediments of the Mackenzie Shelf and Amundsen Gulf, Beaufort Sea (Canada)

In order to document long-term climate cycles and predict future climate trends for the Arctic, we need to look at the geological records to establish the link between historical and pre-historical sea-surface parameters. Dinoflagellate cysts (dinocysts) are used as proxy indicators of sea-surface parameters (temperature, salinity, sea-ice cover, primary productivity) jointly with transfer functions and a modern dinocyst reference database, to reconstruct the evolution of sea-surface conditions at decadal and millennial timescales. Here we present the surface distribution of recent dinocyst assemblages from 34 surface sediment samples collected on the Mackenzie Slope/Amundsen Gulf during the 2004 CASES (Canadian Arctic Shelf Exchange Study) cruise. Dinocyst concentrations in surface sediments are relatively high outside the Mackenzie plume area and increase gradually eastward toward Amundsen Gulf. The cysts of autotrophic dinoflagellates are dominant throughout the study area, while the maximum abundance of heterotrophic taxa is found within the Mackenzie plume. Hierarchical clustering analyses allowed defining two dinocyst assemblages. Assemblage I is located on the Mackenzie Slope and southern Amundsen Gulf, while Assemblage II is located within the Cape Bathurst Polynya area in northern Amundsen Gulf. Both assemblages are dominated by Operculodinium centrocarpum, but are distinguished on the basis of the relative abundance of Islandinium minutum, a taxon generally associated with sea ice. I. minutum is found in lower abundance in the Cape Bathurst Polynya.     

Character phylogenies in Candacia and Paracandacia (Copepoda, Calanoida) and the inevitably paraphyletic nature of many nominal taxa above subspecies level

Examination of the phylogenetic structure of the family Candaciidae shows the genus Paracandacia to comprise a strongly modified branch emerging from the clade commonly denoted as Candacia. This has been confirmed by studying selected character phylogenies. It is argued that the resulting paraphyletic nature of Candacia auct., though in a cladistic context undesirable on theoretical grounds, has to be accepted as inevitable. Recent studies on molluscs and arthropods, viz., have demonstrated that the continuous origin of paraphyletic taxa from previously monophyletic ones is nothing but a naturally occurring process, intrinsically embodied in the course of evolution.     

The role of pelagic fish as forage for the demersal fish community in the southern Bay of Biscay

The small pelagic fish represents the link between nekton and demersal communities, and they are an important food source for some demersal fish species. In the autumns between 1993 and 2002, 74,869 stomach contents of 25 demersal fish species were analysed during the scientific surveys organized by the Instituto Español de Oceanografía. These species represent the demersal fish community of the southern Bay of Biscay. An important part of their diet (39% by volume) was composed of pelagic fish species (e.g. Engraulis encrasicolus, Gadiculus argenteus, Micromesistius poutassou, Trachurus trachurus, Sardina pilchardus, Scomber scombrus). Among all these prey species, the relevance of M. poutassou and G. argenteus stood out because of their high abundance both in the diets and during the scientific surveys. The relevance of pelagic fish as prey increased with predator size, reaching more than 60% of the diet by volume in the length range 25–29 cm. However, fish predators larger than 50 cm depended less on pelagic fish (33%), since they were also able to feed on other sources such as megafaunal invertebrates, mainly cephalopods. The pelagic fish resource was primarily exploited by 12 demersal fish species, with Merluccius merluccius and Zeus faber being the main ones feeding on small pelagics, which was related to the vertical movement of predators and prey through the water column. Survey abundance indices were used as indicators of prey abundance in the ecosystem, both for biomass and number. There was evidence for density-dependant feeding by predators on E. encrasicolus, G. argenteus and T. trachurus, while the main discrepancies between abundance in the stomachs and in the surveys were due to differential availability of prey length classes in the environment. Small prey species and individuals were exploited by most demersal fish while large prey species were less accessible to predators.     

Trace element levels in some commercially valuable fish species from coastal waters of Mediterranean Sea, Egypt

Concentrations of 5 trace elements (Cd, Pb, Cu, Cr, Zn) were determined in muscle of fishes collected from two coastal areas of the Egyptian coast of the Mediterranean Sea west of Alexandria (El-Mex Bay and Eastern Harbour). Sardinella aurita, Alepes djedaba, Siganus luridus, Siganus rivulatus, Sphyraena chrysotoenia, and Scomberomorus commerson were collected from El-Mex Bay. While Boops boops, Lithognathus mormyrus, Sparisoma cretense, Serranus cabrilla and Synodus saurus were collected from the E.H. In all fishes zinc was highest (up to 57 mg/kg) followed by Cr, Cu, Pb and Cd. The concentrations of several metals in fishes were significantly different among the species in each area. For all trace element examined, the concentrations decreased significantly with body weight of some fishes. In contrast, a positive correlation with body weight was found especially for Zn and Cu concentrations in 5 fish species and for Pb in 4 fish species. The concentrations of Cd, Pb and Zn were higher in fishes from El-Mex Bay (3.76, 6.49 and 57.21 mg/kg) than those from Eastern Harbour, whereas the opposite trend was observed for Cu and Cr, revealing the direct sources of trace metal pollution present in El-Mex coastal area. Levels of Cr surpassed the Maximum Permissible Concentration in most fish tissues, followed by Pb and Cd in some species. Cu and Zn presented concentrations below the maximum permissible levels in fish tissues.     

Haplostoma dudleyae sp. nov. (Cyclopoida: Ascidicolidae), parasitic in Eudistoma olivaceum from the Indian River in southern Florida

Haplostoma dudleyae sp. nov. is described and illustrated on the basis of females found in a compound ascidian (Eudistoma olivaceum) collected from the Indian River in southern Florida, USA. Each parasitized zooid has a single female copepod. The egg sacs of the female are paired and, when laid, are almost U-shaped and folded against the dorsal side of the body. Haplostoma dudleyae and two other species (H. canui Chatton and Harant, 1924, and H. humesi Ooishi, 1995) constitute a subgroup within the genus Haplostoma.     

Life cycle strategies of epipelagic copepods in the Southern Ocean

Twelve epipelagic copepod species were reviewed to compare their adaptations to the short primary production season and low temperatures which characterise the Southern Ocean. The species show a spectrum of adaptations, but three broad life cycle strategies were defined: (1) herbivorous in summer, a short reproductive period and winter diapause at depth (Calanoides acutus and possibly Ctenocalanus citer); (2) predominantly omnivorous/detritivorous diet, an extended period of feeding, growth and reproduction and less reliance on diapause at depth (Metridia gerlachei, Calanus propinquus, Calanus simillimus, Oithona similis, Microcalanus pygmaeus, and possibly Oncaea curvata and Oithona frigida); (3) overwintering and feeding within sea ice as early nauplii or copepodids (Stephos longipes and Paralabidocera antarctica). The large species Rhincalanus gigas appears to be intermediate between strategies (1) and (2). Contrasting species from groups (1) and (2), namely C. acutus and O. similis, were selected for more detailed comparison. For C. acutus, maximum (probably food saturated) feeding and egg production rates are well below equivalent values for Calanus spp. at lower latitudes. Likewise, summer growth and moulting rates are slower, and the growth season of this herbivore is only 2–4 months. Therefore, both the low summer temperatures and short primary production season seem to dictate a long (1 year) life cycle for C. acutus. A collation of data on O. similis revealed that its abundance increases about tenfold from the Antarctic shelf northwards to the Polar Frontal Zone, where abundances are similar to those in temperate and tropical shelf seas. In contrast to C. acutus, O. similis appears to remain in the epipelagic and reproduce there year-round, although the food sources which sustain this are still uncertain.     

Ecophysiological growth characteristics and modeling of the onset of the spring bloom in the Baltic Sea

The onset of spring bloom in temperate areas is a transition period where the low productive, winter phytoplankton community is transformed into a high productive spring community. Downwelling irradiance, mixing depth and the ability of the phytoplankton community to utilize the light, are key parameters determining the timing of the onset of the spring bloom. Knowing these parameters would thus provide tools for modeling the spring bloom and enhance our knowledge of ecophysiological processes during this period.Our main objective with this study was to provide data for the growth characteristics of some key species forming the spring bloom in the Gulf of Finland, and to apply those results in a simple dynamic model for the onset of the spring bloom, in order to test if the timing of the spring bloom predicted by the models corresponds to field observations. We investigated the photosynthetic characteristics of three diatoms and two dinoflagellates (Chaetoceros wighamii, Melosira arctica, Thalassiosira baltica, Scrippsiella hangoei and Woloszynskia halophila), at low temperatures (4–5 °C). All of these species are common during spring bloom in the Baltic Sea.Cultures of these species were acclimated to different irradiance regimes prior to measurements of photosynthesis, respiration, pigment concentration and light absorption. We did not find a positive relationship between respiration and growth rate, and we hypothesize that this relationship, which is well established at higher temperatures, is negligible or absent at low temperatures (< 10 °C). Photosynthetic maximum (P_m), and maximum light utilization coefficient (α) was lowest and respiration (R) highest in the dinoflagellates.We made a model of the onset of the spring bloom in the western part of Gulf of Finland, using the obtained data together with monitoring data of mixing depth and water transparency from this area. Model results were compared to field observations of chlorophyll-a (Chl-a) concentration. There was a good agreement between the model predictions and the observed onset of the spring bloom for the diatoms. S. hangoei, however, was not able to reach positive production in the model, and W. halophila had the similar growth characteristics as S. hangoei. Consequently, these species must have other competition strategies enabling them to exist and grow during spring bloom.