Ichthyoplankton community in the Columbia River plume off Oregon: effects of fluctuating oceanographic conditions

Ichthyoplankton samples were collected at approximately 2-week intervals, primarily during spring and summer 1999−2004, from two stations located 20 and 30 km from shore near the Columbia River, Oregon. Northern anchovy (Engraulis mordax) was the most abundant species collected, and was the primary species associated with summer upwelling conditions, but it showed significant interannual and seasonal fluctuations in abundance and occurrence. Other abundant taxa included sanddabs (Citharichthys spp.), English sole (Parophrys vetulus), and blacksmelts (Bathylagidae). Two-way cluster analysis revealed strong species associations based primarily on season (before or after the spring transition date). Ichthyoplankton abundances were compared to biological and environmental data, and egg and larvae abundances were found to be most correlated with sea surface temperature. The Pacific Decadal Oscillation changed sign (from negative to positive) in late 2002 and indicated overall warmer conditions in the North Pacific Ocean. Climate change is expected to alter ocean upwelling, temperatures, and Columbia River flows, and consequently fish eggs and larvae distributions and survival. Long-term research is needed to identify how ichthyoplankton and fish recruitment are affected by regional and largescale oceanographic proces

Horizontal and vertical movements of juvenile bluefin tuna (Thunnus thynnus) in relation to oceanographic conditions of the western North Atlantic, determined with ultrasonic telemetry

We employed ultrasonic transmitters to follow (for up to 48 h) the horizontal and vertical movements of five juvenile (6.8–18.7 kg estimated body mass) bluefin tuna (Thunnus thynnus) in the western North Atlantic (off the eastern shore of Virginia). Our objective was to document the fishes’ behavior and distribution in relation to oceanographic conditions and thus begin to address issues that currently limit population assessments based on aerial surveys. Estimation of the trends in adult and juvenile Atlantic bluefin tuna abundance by aerial surveys, and other fishery-independent measures, is considered a priority. Juvenile bluefin tuna spent the majority of their time over the continental shelf in relatively shallow water (generally less then 40 m deep). Fish used the entire water column in spite of relatively steep vertical thermal gradients (≈24°C at the surface and ≈12°C at 40 m depth), but spent the majority of their time (≈90%) above 15 m and in water warmer then 20°C. Mean swimming speeds ranged from 2.8 to 3.3 knots, and total distance covered from 152 to 289 km (82–156 nmi). Because fish generally remained within relatively con-fined areas, net displacement was only 7.7–52.7 km (4.1–28.4 nmi). Horizontal movements were not correlated with sea surface temperature. We propose that it is unlikely that juvenile bluefin tuna in this area can detect minor horizontal temperature gradients (generally less then 0.5°C/km) because of the steep vertical temperature gradients (up to ≈0.6°C/m) they experience during their regular vertical movements. In contrast, water clarity did appear to influence behavior because the fish remained in the intermediate water mass between the turbid and phytoplankton-rich plume exiting Chesapeake Bay (and similar coastal waters) and the clear oligotrophic water east of the continental shelf.

Coccolithophore species as indicators of surface oceanographic conditions in the vicinity of Azores islands

During summer 2008 and spring 2009, surface oceanographic surveys were carried out around three islands of the Azores archipelago (Terceira, Sao Miguel and Santa Maria) to assess the phytoplankton distribution and associated physico-chemical processes. The Azores archipelago is a major feature in the biogeochemical North Atlantic Subtropical Gyre (NAST) province although its influence on the productivity of the surrounding ocean is poorly known. Surface phytoplankton was studied by microscopy and HPLC (High Precision Liquid Chromatography). The mean values for biomass proxy Chlorophyll a (Chla) ranged from 0.04 to 0.55 mu g L-1 (Chla maximum = 0.86 mu g L-1) and coccolithophores were the most abundant group, followed by small flagellates, Cyanobacteria, diatoms and dinoflagellates being the least abundant group. The distribution of phytoplankton and coccolithophore species in particular presented seasonal differences and was consistent with the nearshore influence of warm subtropical waters from the south Azores current and colder subpolar waters from the north. The satellite-derived circulation patterns showed southward cold water intrusions off Terceira and northward warm water intrusions off Santa Maria. The warmer waters signal was confirmed by the subtropical coccolithophore assemblage, being Discosphaera tubifera a constant presence under these conditions. The regions of enhanced biomass, either resulting from northern cooler waters or from island induced processes, were characterized by the presence of Emiliania huxleyi. Diatoms and dinoflagellates indicated coastal and regional processes of nutrient enrichment and areas of physical stability, respectively.

Interannual variation in commercial oyster (Crassostrea gigas) farming in the sea (Florianopolis, Brazil, 27 degrees 44 ' S; 48 degrees 33 ' W) in relation to temperature, chlorophyll a and associated oceanographic conditions

Aquaculture of filter-feeding bivalve mollusks involves the fruitful conversion of marine particulate organic matter into premium protein of high nutritive value. Culture performance of bivalves is largely dependent on hydrological conditions and directly affected by e. g. temperature and chlorophyll levels. Accordingly, these parameters may be related with seasonality but also with oceanographic features combined with climate events. Yields of Pacific cupped oyster (Crassostrea gigas) reared at commercial procedures in suspended structures (long-lines) in a sheltered bay in Southern Brazil (Santa Catarina State, 27S 43'; 48 W 30') were evaluated in relation to local environmental conditions: sea surface temperature, chlorophyll a concentration, and associate effects of cold fronts events and El Nino and La Nina periods. Outputs from four consecutive commercial crop years were analyzed (2005/06, 2006/07, 2007/08, 2008/09) in terms of oyster survival and development time during the following grow-out phases of the culture cycle: seed to juvenile, juvenile to adult, adult to marketable. Since culture management and genetics were standardized significant differences verified among crop performance could be mostly related to environmental effects. Time series of temperature and chlorophyll a (remote sensing data) from crop periods displayed significant seasonal and interannual variation. As expected, performance during initial grow-out stages (seed to juvenile) was critical for final crop yield. Temperature was the main factor affecting survival in these initial stages with a trend of negative correlation, though not statistically significant. On the other hand, oyster development rate was significantly and positively affected by chlorophyll a concentration. Chlorophyll a values could be increased by upwelled cold nutrient-rich South Atlantic Central Water (SACW, related to predominant Northern winds) though further dependent on occurrence of Southern winds (cold fronts) to assist seawater penetration into the sheltered farming area. Lower salinity nutrient-rich northward drifted waters from La Plata River discharge may also result in chlorophyll a rise in the farming area. The El Nino period (July 2006 to February 2007) coincided with lower chlorophyll a levels in the farming site that may be related to both decreased number of cold fronts as well as predominance of Northern winds that retain northward spreading of La Plata River discharge waters. In contrast, the La Nina period (August 2007 to June 2008) corresponded to higher chlorophyll a values in the farming area by both upwelling of SACW and penetration of La Plata River discharge water assisted by increased occurrence of Southern winds and cold fronts. The recognition of the potentially changing climate and effects upon the environment will be an important step in planning future development of bivalve aquaculture.

Oceanographic observations, North Pacific Ocean Station Victor, October 1966 - October 1967 : Seasonal variation of oceanographic conditions from Ocean Station Victor to the coast of Japan along 34 ̊N latitude, January 1966 - October 1967 /

"CG 373-27."

Oceanographic conditions in the northern Baffin Bay region, 24 July-6 August, 1970 /

"CG 373-54."

Oceanographic conditions in Nares Strait, August-September 1970 /

"CG 373-57."

Study of the oceanographic conditions in the Caribbean in 2003

[EN]A meridional hydrographic section was made in October 2003 at 66ºW from the coast of Venezuela to Puerto Rico. In this report, we concentrate from surface to 1700 m depth in the Caribbean. The data show two distinct water masses with different origins: Caribbean Surface Water, with salinity values less that 35.5, and Subtropical Underwater (SUW), with subsurface salinity higher than 37, with their source in the North Atlantic and subtropics respectively, as previously observed. Different velocity patterns in the water masses from Atlantic Ocean to the Caribbean are observed. Mass transport through the section is westward and about 30 Sv that matches the transport of the Florida Current.

Water Temperatures and Climatological Conditions South of New England, 1974-83

From 1974 through 1983, we conducted monitoring to provide the first long-term, year-round record of sea water temperatures south of New England from surface to bottom, and from nearshore to the continental slope. Expendable bathythermograph transects were made approximately monthly during the ten years by scientists and technicians from numerous institutions, working on research vessels that traversed the continental shelf off southern New England. Ten-year (1974-83) means and variability are presented for coastal and bottom water temperatures, for mid-shelf water column temperatures, and for some atmospheric and oceanographic conditions that may influence shelf and upper-slope water temperatures. Possible applications of ocean temperature monitoring to fishery ecology are noted. Some large departures from mean conditions are discussed; particularly notable during the decade were the response of water temperatures to the passage of Gulf Stream warm-core rings, and the magnitude and persistence of shelf-water cooling associated with air temperatures in three successive very cold winters (1976-77, 1977-78, and 1978-79). (PDF file contains 51 pages.)

An ecological characterization of the Stellwagen Bank National Marine Sanctuary Region: oceanographic, biogeographic, and contaminants assessment

The mission of NOAA’s National Marine Sanctuary Program (NMSP) is to serve as the trustee for a system of marine protected areas, to conserve, protect, and enhance their biodiversity, ecological integrity, and cultural legacy while facilitating compatible uses. Since 1972, thirteen National Marine Sanctuaries, representing a wide variety of ocean environments, have been established, each with management goals tuned to their unique diversity. Extending from Cape Ann to Cape Cod across the mouth of Massachusetts Bay, Stellwagen Bank National Marine Sanctuary (NMS) encompasses 2,181 square kilometers of highly productive, diverse, and culturally unique Federal waters. As a result of its varied seafloor topography, oceanographic conditions, and high primary productivity, Stellwagen Bank NMS is utilized by diverse assemblages of seabirds, marine mammals, invertebrates, and fish species, as well as containing a number of maritime heritage resources. Furthermore, it is a region of cultural significance, highlighted by the recent discovery of several historic shipwrecks. Officially designated in 1992, Stellwagen Bank became the Nation’s twelfth National Marine Sanctuary in order to protect these and other unique biological, geological, oceanographic, and cultural features of the region. The Stellwagen Bank NMS is in the midst of its first management plan review since designation. The management plan review process, required by law, is designed to evaluate, enhance, and guide the development of future research efforts, education and outreach, and the management approaches used by Sanctuaries. Given the ecological and physical complexity of Stellwagen Bank NMS, burgeoning anthropogenic impacts to the region, and competing human and biological uses, the review process was challenged to assimilate and analyze the wealth of existing scientific knowledge in a framework which could enhance management decision-making. Unquestionably, the Gulf of Maine, Massachusetts Bay, and Stellwagen Bank-proper are extremely well studied systems, and in many regards, the scientific information available greatly exceeds that which is available for other Sanctuaries. However, the propensity of scientific information reinforces the need to utilize a comprehensive analytical approach to synthesize and explore linkages between disparate information on physical, biological, and chemical processes, while identifying topics needing further study. Given this requirement, a partnership was established between NOAA’s National Marine Sanctuary Program (NMSP) and the National Centers for Coastal Ocean Science (NCCOS) so as to leverage existing NOAA technical expertise to assist the Sanctuary in developing additional ecological assessment products which would benefit the management plan review process.

Report on the oceanographic investigations carried out at the Sofala Bank by the Soviet trawler "Sevastopolsky rybak" in September-December 1982

In September-December 1982 a fisheries research cruise was carried out at the Sofala Bank by the SRTM "Sevastopolsky Rybak". Oceanographic investigations have been conducted in association with the fisheries research. Three coverages were made of the Sofala Bank each lasting for slightly less than three weeks. This will allow for three descriptions of the oceanographic conditions in the area, with some reference being made to variability. This paper is just a preliminary report of those investigations.

Predicting future thermal habitat suitability of competing native and invasive fish species: from metabolic scope to oceanographic modelling

Global increase in sea temperatures has been suggested to facilitate the incoming and spread of tropical invaders. The increasing success of these species may be related to their higher physiological performance compared with indigenous ones. Here, we determined the effect of temperature on the aerobic metabolic scope (MS) of two herbivorous fish species that occupy a similar ecological niche in the Mediterranean Sea: the native salema (Sarpa salpa) and the invasive marbled spinefoot (Siganus rivulatus). Our results demonstrate a large difference in the optimal temperature for aerobic scope between the salema (21.8°C) and the marbled spinefoot (29.1°C), highlighting the importance of temperature in determining the energy availability and, potentially, the distribution patterns of the two species. A modelling approach based on a present-day projection and a future scenario for oceanographic conditions was used to make predictions about the thermal habitat suitability (THS, an index based on the relationship between MS and temperature) of the two species, both at the basin level (the whole Mediterranean Sea) and at the regional level (the Sicilian Channel, a key area for the inflow of invasive species from the Eastern to the Western Mediterranean Sea). For the present-day projection, our basin-scale model shows higher THS of the marbled spinefoot than the salema in the Eastern compared with the Western Mediterranean Sea. However, by 2050, the THS of the marbled spinefoot is predicted to increase throughout the whole Mediterranean Sea, causing its westward expansion. Nevertheless, the regional-scale model suggests that the future thermal conditions of Western Sicily will remain relatively unsuitable for the invasive species and could act as a barrier for its spread westward. We suggest that metabolic scope can be used as a tool to evaluate the potential invasiveness of alien species and the resilience to global warming of native species.

Influence of environmental conditions on foraging behaviour and its consequences on reproductive performance in little penguins

During the breeding season, seabirds are central place foragers and have to adapt their foraging behaviour in response to environmental variation to maximize efficiency and reproductive output. Due to its small size and swimming mode of transport, the little penguin (Eudyptula minor) is expected to be greatly susceptible to such fluctuations. The links between local-, meso- and macro-scale environmental conditions and inter-annual variation in foraging behaviour and reproductive performance of little penguins were investigated during three consecutive breeding seasons at two colonies in south-eastern Australia marked by contrasting oceanographic conditions. At a local scale, foraging effort was correlated positively with wind direction and negatively with wave height. At a regional scale, foraging effort of individuals from both colonies was negatively correlated with higher sea surface temperature (SST) off the Bonney Coast in the previous Austral summer, suggesting a weaker Bonney Upwelling event and a cascade of effects throughout the Bass Strait region. At a larger scale, the El Niño Southern Oscillation was also found to correlate with foraging behaviour, with lower foraging effort being observed during La Niña event. Although individuals increased their foraging effort during years with poorer conditions, they were not able to maintain high breeding success. In addition, peak egg-laying was found to coincide with a decrease in local SST and a peak of sea surface chlorophyll-a concentration. In conclusion, these results highlight how different environmental conditions could influence foraging behaviour and ultimately reproductive success of little penguins. It also showed that under certain circumstances, these individual strategies were not sufficient to cope with environmental variability.

Hydrographic Conditions Off Northern Chile During the 1996-1998 La Niña and El Niño Events

The evolution of oceanographic conditions in the upwelling region off northern Chile (18 degrees-24 degrees S) between 1996 and 1998 (including the 1997-1998 El Niño) is presented using hydrographic measurements acquired on quarterly cruises of the Chilean Fisheries Institute, with sea surface temperature (SST), sea level, and wind speeds from Arica (18.5 degrees S), Iquique (20.5 degrees S), and Antofagasta (23.5 degrees S) and a time series of vertical temperature profiles off Iquique. Spatial patterns of sea surface temperature and salinity from May 1996 to March 1997 followed a normal seasonal progression, though conditions were anomalously cool and fresh. Starting in March 1997, positive anomalies in sea level and sea surface temperature propagated along the South American coast to 37 degrees S. Maximum sea level anomalies occurred in two peaks in May-July 1997 and October 1997 to February 1998, separated by a relaxation period. Maximum anomalies (2 degrees C and 0.1 practical salinity units (psu)) extended to 400 m in December 1997 within 50 km of the coast. March 1998 presented the largest surface anomalies (> 4 degrees C and 0.6 psu). Strong poleward flow (20-35 cm s(-1) ) occurred to 400 m or deeper during both sea level maxima and weaker (10 cm s(-1) ) equatorward flow followed each peak. By May 1998, SST had returned to the climatological mean, and flow was equatorward next to the coast. However, offshore salinity remained anomalously high owing to a tongue of subtropical water extending southeast along the Peruvian coast. Conditions off northern Chile returned to normal between August and December 1998. The timing of the anomalies suggests a connection to equatorial waves. The progression of the 1997-1998 El Niño was very similar to that of 1982-1983, though with different timing with respect to seasons.