Rapid shipboard identification and enumeration of pelagic marine fish eggs by a simple photographic technique (note)

A technique is described for obtaining rapid high‐quality silhouette photographs of plankton samples at sea. This technique was designed to facilitate identification and enumeration of pelagic marine fish eggs in near real‐time. It uses readily available photographic materials and unlike previously described techniques, the silhouettes are recorded directly on to photographic paper rather than film. The resolution is adequate for microscopic measurements. Examples are presented from a cruise off Westland, New Zealand, which investigated the distribution of hoki eggs.     

Climate variance influence on the non-stationary plankton dynamics

We examined plankton responses to climate variance by using high temporal resolution data from 1988 to 2007 in the Western English Channel. Climate variability modified both the magnitude and length of the seasonal signal of sea surface temperature, as well as the timing and depth of the thermocline. These changes permeated the pelagic system yielding conspicuous modifications in the phenology of autotroph communities and zooplankton. The climate variance envelope, thus far little considered in climate-plankton studies, is closely coupled with the non-stationary dynamics of plankton, and sheds light on impending ecological shifts and plankton structural changes. Our study calls for the integration of the non-stationary relationship between climate and plankton in prognostic models on the productivity of marine ecosystems.     

A comparison of biological trends from four marine ecosystems: Synchronies, differences, and commonalities

Major features of four marine ecosystems were analyzed based on a broad range of fisheries-associated datasets and a suite of oceanographic surveys. The ecosystems analyzed included the Gulf of Maine/Georges Bank in the Northwest Atlantic Ocean, the Norwegian/Barents Seas in the Northeast Atlantic Ocean, and the eastern Bering Sea and the Gulf of Alaska in the Northeast Pacific Ocean. We examined survey trends in major fish abundances, total system fish biomass, and zooplankton biomasses. We standardized each time series and examined trends and anomalies over time, using both time series and cross-correlational statistical methods. We compared dynamics of functionally analogous species from each of these four ecosystems. Major commonalities among ecosystems included a relatively stable amount of total fish biomass and the importance of large calanoid copepods, small pelagic fishes and gadids. Some of the changes in these components were synchronous across ecosystems. Major differences between ecosystems included gradients in the magnitude of total fish biomass, commercial fish biomass, and the timing of major detected events. This work demonstrates the value of comparative analysis across a wide range of marine ecosystems, suggestive of very few but none-the-less detectable common features across all northern hemisphere ocean systems.     

Sources of plastic marine debris on beaches of Korea: More from the ocean than the land

Reduction of marine debris requires knowledge of its sources. Sources of plastic marine debris found on six beaches of Korea were estimated. Samples larger than 25 mm were collected from 10 quadrats of 5 × 5 m for each beach in spring 2013. The total 752 items (12,255 g) of debris comprised fiber and fabric (415 items, 6,909 g), hard plastic (120 items, 4,316 g), styrofoam (93 items, 306 g), film (83 items, 464 g), foamed plastic other than styrofoam (21 items, 56 g), and other polymer (20 items, 204 g). With the probable sources allocated to each of 55 debris types, the source of 56% of all the collected debris appeared to be oceanbased and 44% was land-based. Priorities of policy measures to reduce marine debris should be different from regions to regions as the main sources of debris may differ.     

汕头沿岸水体沙壳纤毛虫季度变化

在2007年枯水期(4月)和丰水期(11月)期间,对汕头沿岸海区沙壳虫进行了采样研究,探讨了沙壳虫的空间分布和种类组成.调查发现,除了表层海水温度以外,表层海水盐度、硝酸盐浓度、硅酸盐浓度均是春季低于秋季.在两个季节的5个采样点共鉴定出7属14种沙壳纤毛虫,其中优势种均为简单薄铃虫Lepmtintinnus simpl...     

Impacts of elevated CO2 on particulate and dissolved organic matter production: microcosm experiments using iron-deficient plankton communities in open subarctic waters

Response of phytoplankton to increasing CO₂ in seawater in terms of physiology and ecology is key to predicting changes in marine ecosystems. However, responses of natural plankton communities especially in the open ocean to higher CO₂ levels have not been fully examined. We conducted CO₂ manipulation experiments in the Bering Sea and the central subarctic Pacific, known as high nutrient and low chlorophyll regions, in summer 2007 to investigate the response of organic matter production in iron-deficient plankton communities to CO₂ increases. During the 14-day incubations of surface waters with natural plankton assemblages in microcosms under multiple pCO₂ levels, the dynamics of particulate organic carbon (POC) and nitrogen (PN), and dissolved organic carbon (DOC) and phosphorus (DOP) were examined with the plankton community compositions. In the Bering site, net production of POC, PN, and DOP relative to net chlorophyll-a production decreased with increasing pCO₂. While net produced POC:PN did not show any CO₂-related variations, net produced DOC:DOP increased with increasing pCO₂. On the other hand, no apparent trends for these parameters were observed in the Pacific site. The contrasting results observed were probably due to the different plankton community compositions between the two sites, with plankton biomass dominated by large-sized diatoms in the Bering Sea versus ultra-eukaryotes in the Pacific Ocean. We conclude that the quantity and quality of the production of particulate and dissolved organic matter may be altered under future elevated CO₂ environments in some iron-deficient ecosystems, while the impacts may be negligible in some systems.     

海洋微塑料污染与塑料降解微生物研究进展

塑料垃圾在近海、大洋水体和沉积物中均广泛存在,并不断累积,对海洋生态系统构成了重大威胁,引起了国际社会的高度关注。本研究从环境生态和塑料降解微生物两个角度回顾了近几年相关方向上的研究进展,包括国内外海洋塑料特别是海洋微塑料在近海与深海等环境中的分布与丰度,以及近海、大洋等环境中降解菌多样性及其降解机制。总体而言,微塑料广泛分布在多种海洋环境,特别是在河口和近海的海水和沉积物,近岸沙滩,以及大洋环流中心;目前已报道的塑料降解菌及其降解酶主要来自陆地土壤和塑料垃圾处理环境,并以聚对苯二甲酸乙二酯(Polyethylene Terephthalate,PET)降解菌和降解酶的研究最为深入。当前,中国科学家已在近海、大洋深海(深渊)以及极地等大洋环境中,开展了微塑料分布特征和丰度调查,并在生态危害方面开展了研究,但在海洋塑料降解微生物方面还鲜有报道。塑料在海洋环境中的最终归宿以及微生物在塑料降解过程中的作用亟待评估,建议在大洋深海科考中整体布局、联合开展这两个方面的相关研究。     

Plankton response to El Niño 1997–1998 and La Niña 1999 in the southern region of the California Current

The IMECOCAL Program began in 1997, with the objective of sampling plankton systematically in the Mexican region of the California Current. We present results of chlorophyll a concentrations and zooplankton displacement volumes for the eight cruises from September 1997 to October 1999. The abundance of 22 zooplankton groups was also analyzed for the first four cruises. The response of plankton to the 1997–1998 El Niño was atypical. From September 1997 to January 1998, chlorophyll a and zooplankton volume were at typical values (median integrated chlorophyll was 27 mg/m² and zooplankton 100 ml/1000 m³ in 9801/02). After the peak of El Niño, the system shifted to cooler conditions. Integrated chlorophyll gradually increased to a median of 77 mg/m² in April 1999. In contrast, zooplankton volumes decreased from October 1998 onward, despite favorable phytoplankton availability in 1999. Zooplankton structure was dominated by copepods and chaetognaths through the ENSO cycle, but interannual changes were evident. In the fall of 1997 there was a higher proportion of copepods, chaetognaths, and other minor groups, while the fall of 1998 zooplankton was richer in salps and ostracods. Historical data from previous Baja California CalCOFI cruises indicated that zooplankton volumes measured during the IMECOCAL cruises were above the long-term mean for the period 1951–1984. This suggests a differential response of plankton to the El Niño of 1997–1998 compared to the El Niño of 1957–1959. Regional differences in zooplankton volumes were also found, with central Baja California having 41% higher biomass than northern Baja California. Volumes from both regions were larger than those recorded by CalCOFI off southern California during 1997–1998, but the situation was reversed in 1999. The higher biomasses in the 1997–1998 El Niño can be attributed to high abundance of salps, which showed an affinity with warm, saline water.     

Phytoplankton community structure in Otsuchi Bay,northeastern Japan,after the 2011 off the Pacific coast of Tohoku Earthquake and tsunami

The tsunami caused by the 2011 off the Pacific coast of Tohoku Earthquake seriously damaged the Pacific coast of northeastern Japan. In addition to its direct disturbance, a tsunami can indirectly affect coastal pelagic ecosystems via topographical and environmental changes. We investigated seasonal changes in the phytoplankton community structure in Otsuchi Bay, northeastern Japan, from May 2011, which was 2 months after the tsunami, to May 2013. The phytoplankton species composition in May 2011 was similar to that observed in May 2012 and 2013. The present results are consistent with the dominant species and water-mass indicator species of phytoplankton in past records. These results suggest that there was no serious effect of the tsunami on the phytoplankton community in Otsuchi Bay. Community analysis revealed that two distinct seasonal communities appeared in each year of the study period. The spring–summer community was characterized by warm-water Chaetoceros species, and dinoflagellates appeared from May to September. The fall–winter community was characterized by cold neritic diatoms, which appeared from November to March. The succession from the spring–summer community to the fall–winter community took place within a particular water mass, and the fall–winter community appeared in both the surface water and the Oyashio water mass, suggesting that water-mass exchange is not the only factor that determines the phytoplankton community structure in Otsuchi Bay.     

Differences in the structure of the lower trophic levels of pelagic ecosystems in the eastern and western subarctic Pacific

To illustrate areal differences in the structure of lower trophic levels of the pelagic ecosystems in the subarctic Pacific, data collected in the quasi-steady state summer/fall conditions were analysed for five areas, i.e. the Bering Basin, Western Subarctic Gyre, the area south of the Aleutians, the Gulf of Alaska, and the Oyashio Region. Average values of stock size of four components of the lower trophic levels showed a clear difference between areas with ranges of 7.5-fold for nitrate, 3.0 for chlorophyll a, 9.9 for microzooplankton, and 2.4 for mesozooplankton. Such differences were more striking when the structure of the lower trophic levels was expressed as a biomass pyramid. In the Gulf of Alaska, Western Subarctic Gyre, and south of the Aleutians, the relative biomass of microzooplankton to phytoplankton is large and large amounts of nitrate remained unused. In addition to possible iron limitation, grazing control by the microzooplankton on small phytoplankton must be substantial in these areas. Conversely, in the Oyashio Region, the nitrate stock is very small indicating higher efficiency of nitrate consumption by phytoplankton. However, since phytoplankton and zooplankton stocks are not particularly large, their products are likely to be transferred, also efficiently, to the higher trophic levels such as planktivorous pelagic fish. The situation in the Bering Basin is intermediate between the Oyashio Region and the other three areas. Inter-annual fluctuations in stock size of the planktivorous fish which migrate into the Oyashio Region in summer/fall were quite large. However, the inter-annual variation of mesozooplankton biomass was small, suggesting the existence of certain mechanisms to stabilize plankton abundance under increasing predation pressure. As a result, the increasing fish stocks likely keep the transfer efficiency from nitrate through to fish higher, at least in the Oyashio Region.     

Chemical properties of colored dissolved organic matter in the sea-surface microlayer and subsurface water of Jiaozhou Bay, China in autumn and winter

The distribution and chemical properties of chromophoric dissolved organic matter (CDOM) in the Jiaozhou Bay, China were examined during four cruises in 2010-2011. The influence of freshwater and industrial and municipal sewage along the eastern coast of the bay was clearly evident as CDOM levels (defined as a 305 ), and dissolved organic carbon (DOC) concentrations were well correlated with salinity during all the cruises. Moreover, DOC concentrations were significantly correlated with chlorophyll a concentrations in the surface microlayer as well as in the subsurface water. The concentrations of DOC and CDOM displayed a gradually decreasing trend from the northwestern and eastern coast to the central bay, and the values and gradients of their concentrations on the eastern coast were generally higher than those on the western coast. In addition, CDOM and DOC levels were generally higher in the surface microlayer than in the subsurface water. In comparison with DOC, CDOM exhibited a greater extent of enrichment in the microlayer in each cruise, with average enrichment factor (E F ) values of 1.38 and 1.84, respectively. Four fluorescent components were identified from the surface microlayer and subsurface water samples and could be distinguished as peak A, peak T, peak B and peak M. For all the cruises, peak A levels were higher in the surface microlayer than in the subsurface water. This pattern of variation might be attributed to the terrestrial input.     

Impact of monsoon-driven circulation on phytoplankton assemblages near fringing reefs along the east coast of Hainan Island,China

Monsoonal hydrodynamic prevails over the east coast of Hainan Island induced by southwest monsoon (SWM) and northeast monsoon (NEM) which drives coastal Ekman divergence/convergence cycle and the reversal of Guangdong coastal current (GCC) between the sGCC in the SWM season and nGCC in the NEM season. We report the control of such hydrodynamics on biological properties such as phytoplankton assemblages in the east coast of Hainan Island. Physico-chemical and biological observations were carried out in two oceanographic cruises along the east coast of Hainan Island during SWM period (July–August) of 2008 and NEM period (March–April) of 2009. Results indicated that phytoplankton assemblages in coastal regions (fringing reefs and coastal shelf) changed dramatically accompanied with the reverse of monsoonal hydrodynamic processes, with chain-forming diatoms (mainly, Pseudo-nitzschia spp. and Thalassionema nitzschioides) dominating during SWM cruise when coastal Ekman divergence and the sGCC were prevailed, but the pelagic Noctiluca scintillans and Trichodesmium erythraeum dominating during NEM cruise when coastal Ekman convergence and the nGCC were prevailed. Furthermore, phytoplankton assemblages in fringing reefs along coastline were somewhat different from ones of coastal shelf, as fringing reefs are just located at dynamic boundary of offshore (or onshore) Ekman transport processes. Offshore diffusion of pelagic cells (such as T. erythraeum) driven by offshore Ekman transport process led to the lower abundance of T. erythraeum in fringing reefs than ones in coastal shelf during SWM cruise; on the contrary, onshore aggregation of pelagic cells (such as N. scintillans and T. erythraeum) driven by onshore Ekman transport process leads to higher abundances of N. scintillans and T. erythraeum in fringing reefs than ones in coastal shelf during NEM cruise; especially, N. scintillans formed bloom in fringing reefs. Last, we suggested that hydrodynamic processes must be taken into account in scientific management of fringing coral reefs health of the east coast of Hainan Island, especially during northeast monsoon season when blooming specie cells (such as N. scintillans) could be introduced from eutrophic South China mainland coast to the east coast of Hainan Island and piled to high-abundance at fringing reefs by monsoonal hydrodynamics.     

Sediment transport in the Yellow Sea and East China Sea

Eight survey cruises in different seasons have been conducted in the Yellow Sea (YS) and East China Sea (ECS) during the period from 2000 to 2008. Suspended sediment concentration (SSC) and hydrological data were collected during each cruise. Data analysis showed that total suspended sediment mass was approximately 0.18 × 10⁹ tons in the surveyed area during spring and autumn seasons. Highly turbid waters were found in the shallow waters between the Subei coast, the Changjiang estuary and the Zhejiang coast with seasonal variations.     

Abundance and Distribution Patterns of Nekton and Micronekton in the Northern California Current Transition Zone

The epipelagic and mesopelagic nekton communities of the northern California Current have been sampled somewhat continuously over the last four decades with bottom and pelagic trawls, small midwater trawls, and purse seines. We review the zoogeography and community and environmental associations of the dominant pelagic micronekton and nekton species in this region with a view to understanding their role in this dynamic marine ecosystem. As is typical of many upwelling eastern boundary current regions, the pelagic biomass is dominated by a few species that fluctuate dramatically through time. The abundance trends of pelagic nekton caught in this region demonstrated large-scale ecosystem changes about the time of the regime shifts of 1976/77 and 1989 and possibly another beginning in 1999. The rapidity of the changes in composition indicates that the response was due to a change in migration or distribution patterns as opposed to recruitment patterns. The 1989 regime shift led to a dramatic increase in sardine and a decrease in anchovy populations. The most pronounced interannual signals were attributed to strong El Niño/Southern Oscillation (ENSO) conditions in 1983 and 1998 that altered the latitudinal ranges and proximity to the coast of many pelagic species. Variations in abundance and cross-shelf distribution patterns were noted for both pelegic nekton and micronektonic from surveys off California, Oregon, and Washington.     

Carbon monoxide concentrations in surface waters of the east tropical pacific in 1974: comparison with earlier values

Concentrations of carbon monoxide were measured in the surface waters of the east tropical Pacific during a cruise aboard USNS “Hayes” from Ecuador to Panama via Hawaii and Tahiti in the late winter and early spring of 1974. Data comparisons were made for time spans of 1.3–3.7 years at several locations where the cruise track intersected or closely paralleled portions of our two earlier Pacific cruise tracks. The comparisons showed remarkable consistency, considering the range of variability of carbon monoxide concentration. Latitudinal variations of concentrations found during the earlier cruises were reconfirmed.     

Distribution and abundance of small plastic debris on beaches in the SE Pacific (Chile): A study supported by a citizen science project

The accumulation of large and small plastic debris is a problem throughout the world's oceans and coastlines. Abundances and types of small plastic debris have only been reported for some isolated beaches in the SE Pacific, but these data are insufficient to evaluate the situation in this region. The citizen science project "National Sampling of Small Plastic Debris” was supported by schoolchildren from all over Chile who documented the distribution and abundance of small plastic debris on Chilean beaches. Thirty-nine schools and nearly 1000 students from continental Chile and Easter Island participated in the activity. To validate the data obtained by the students, all samples were recounted in the laboratory. The results of the present study showed that the students were able to follow the instructions and generate reliable data. The average abundance obtained was 27 small plastic pieces per m² for the continental coast of Chile, but the samples from Easter Island had extraordinarily higher abundances (>800 items per m²). The abundance of small plastic debris on the continental coast could be associated with coastal urban centers and their economic activities. The high abundance found on Easter Island can be explained mainly by the transport of plastic debris via the surface currents in the South Pacific Subtropical Gyre, resulting in the accumulation of small plastic debris on the beaches of the island. This first report of the widespread distribution and abundance of small plastic debris on Chilean beaches underscores the need to extend plastic debris research to ecological aspects of the problem and to improve waste management.     

Ichthyoplankton assemblages off northern Namibia

The continental shelf off Namibia is influenced by the Benguela Current with variable intensity year-round, and upwelling there has an important effect on the spawning habits of fish. During three cruises to northern Namibia, carried out in intensive and weak upwelling seasons, there were notable differences in the ichthyoplankton fauna. General features of the hydrography and plankton and an index of larval diversity calculated for all ichthyoplankton stations occupied during the three cruises are presented. Low larval diversity seemed to be related to centres of upwelling and, conversely, high larval diversity to hydrological stability. Principal components analysis was used to study the ichthyoplankton association patterns and their relation to external factors. In cruises carried out in upwelling periods (winter and spring) the main factors were identified as depth and latitude. A good relationship was found between species in the north of the survey area and warmer Angolan water during the autumn cruise. Hierarchical classification methods were also used, the points coefficient of correlation being used as a similarity index and the U PGM A as algorithm. Results obtained by this method of classification coincided with those obtained from principal components analysis.     

Sediment reworking by a polychaete, <Emphasis Type="Italic">Perinereis aibuhitensis</Emphasis>, in the intertidal sediments of the Gomso Bay,Korea

Bioturbation, especially sediment reworking by the activities of macroinvertebrates, such as feeding and burrowing, is one of the major processes that affect the physical, chemical, and biological characteristics of marine sediments. Given the importance of sediment reworking, this study was designed to evaluate the sediment reworking rate of a polychaete, Perinereis aibuhitensis, which is dominant in the upper tidal flats on the west coast of Korea, based on quantification of pellet production during spring and fall surveys. The density of individuals was higher in fall than in spring, whereas, due to a difference in the proportion of adults between the two seasons, the morphometric dimensions of the worm and its pellets were significantly longer and heavier in the spring. Hourly pellet production per inhabitant and density were closely related, with pellet production gradually decreasing as density increased. Daily pellet production was much higher in spring than in fall, mostly due to an increase in daytime production. The sediment reworking rate of Perinereis was similar in the two seasons in which observations were made and depended on its density and the sediment reworking rate per individual. The overall sediment reworking rate of Perinereis was 31 mm yr^?1 based on its density in the study area.     

Comprehensive Research of Ecosystems of Hydrothermal Vents and Cold Seeps in the Bering Sea (Cruise 82 of the R/V Akademik M.A. Lavrentyev)

Oceanology - On cruise 82 voyage of the R/V Akademik M.A. Lavrentyev, comprehensive studies of ecosystems associated with hydrothermal vents and cold seeps in the Bering Sea were carried out. New...     

Seasonal and spatial variations of zooplankton in the central and southeastern Bering Sea during the mid-1990s

Hydrographic and plankton surveys were conducted over the basin and slope of the southeastern Bering Sea during April, June/July and September of 1994 and in June/July 1995, and seasonal and spatial variations of zooplankton community were investigated in relation to the oceanographic conditions. In July 1994, sea surface temperature (SST) ranged 5.3–8.7 °C, and the thermocline was between 30 and 50 m. In July 1995, however, SST was warmer (7.3–12.4 °C), and the thermocline was shallower (20–30 m). The thermal front at the shelf was also stronger in July 1995 than in July 1994. Surface salinity was higher in 1994 than 1995. A total of 17 taxonomic groups of zooplankton were identified from the plankton samples. In 1994, the highest density was observed in September. Copepods were the major taxon during all surveys. While some taxa such as euphausiids, ostracods, and Neocalanus spp. were most abundant in spring, others such as Calanus spp., Metridia pacifica, chaetognaths, and pteropods were most abundant in September. Adults and late-stage copepodites of Eucalanus bungii were abundant in spring, and were replaced by 1st–3rd stages of copepodites in summer. Zooplankton density was ca. 4 times higher in 1995 than in 1994, in part because of warm water temperature.