Oceanographic Factors Research Articles

Seabirds as Ecological Indicators in Late Cretaceous Marine Environments

In modern marine ecosystems, seabirds are considered indicators of ecological hotspots because their biogeographic distribution is correlated with physical, chemical, and biological oceanographic factors. Pursuit diving seabirds – those that actively pursue prey underwater – are even more limited in distribution and closely tied to oceanographic factors, as diving ability is often gained at the expense of flight capabilities. Today, pursuit diving seabirds are generally restricted to waters cooler than 15ºC. By contrast, the Late Cretaceous was characterized by greenhouse climate and high sea levels that provided marine paleoenvironments with no modern analogs. Even though waters in the Western Interior Seaway (WIS) were warmer than 15ºC, they were host to pursuit diving seabirds called hesperornithiforms. The presence of hesperornithiforms in warm waters indicates that different biotic and abiotic factors affected Late Cretaceous epicontinental ecosystems than affect modern oceans. Together, ecosystem structure and the unique oceanographic factors characterizing epicontinental seas both contribute to differences in seabird biogeography between the Late Cretaceous and today.

Vulnerability Assessment of Mangrove Habitat to the Variables of the Oceanography Using CVI Method (Coastal Vulnerability Index) in Trimulyo Mangrove Area, Genuk District, Semarang

Some functions of mangrove areas in coastal ecosystems as a green belt, because mangrove serves as a protector of the beach from the sea waves, as a good habitat for coastal biota and for nutrition supply. Decreased condition or degradation of mangrove habitat caused by several oceanographic factors. Mangrove habitats have some specific characteristics such as salinity, tides, and muddy substrates. Considering the role of mangrove area is very important, it is necessary to study about the potential of mangrove habitat so that the habitat level of mangrove habitat in the east coast of Semarang city is known. The purpose of this research is to obtain an index and condition of habitat of mangrove habitat at location of research based on tidal, salinity, substrate type, coastline change. Observation by using purposive method and calculation of habitat index value of mangrove habitat using CVI (Coastal Vulnerability Index) method with scores divided into 3 groups namely low, medium and high. The results showed that there is a zone of research belonging to the medium vulnerability category with the most influential variables is because there is abrasion that sweeps the mangrove substrate. Trimulyo mangrove habitat has high vulnerable variable of tidal frequency, then based on value variable Salinity is categorized as low vulnerability, whereas for mangrove habitat vulnerability based on variable type of substrate belong to low and medium vulnerability category. The CVI values of mangrove habitats divided into zones 1; 2; and 3 were found to varying values of 1.54; 3.79; 1.09, it indicates that there is a zone with the vulnerability of mangrove habitat at the study site belonging to low and medium vulnerability category.

Oceanographic drivers of near-colony seabird foraging site use in tropical marine systems

Wedge-tailed shearwaters of Australia’s southern Great Barrier Reef (GBR), obtain food for their chicks on short trips adjacent to the breeding colony. GPS tracking (from February to April in 2013 and 2014) indicated that most trips were of 1 d duration (70 to 85%) and that all were within 300 km of the colony. Oceanographic characteristics of foraging and non-foraging areas were compared to identify mechanisms driving prey availability. Foraging generally occurred adjacent to the Capricorn Shelf, where the largest oceanographic feature in the region, the Capricorn Eddy, creates increased frontal activity and upwellings. Shearwaters consistently revisited 4 bathymetrically and topographically distinct foraging zones influenced by this mesoscale eddy. In 2013, strong sea surface temperature (SST) fronts associated with relatively intense eddy activity influenced foraging activity in all foraging zones. In 2014 the dominant oceanographic factors influencing foraging were SST and chlorophyll a concentration ([chl a]) or their anomalies. However, these influences varied among zones, suggesting a weakened effect of the eddy and elevated importance of fine-scale phenomena such as localised upwellings. Foraging in the coastal foraging zone was also significantly influenced by terrestrial inputs: specifically, birds foraged in association with freshwater flood plumes with higher [chl a]. The oceanographic mechanisms underlying prey availability to shearwaters in this system are tightly linked to variations in climatic conditions. Consequently, predicted changes associated with climate change, such as increased frequency or severity of El Nino events, are likely to seriously diminish the profitability of identified foraging locations and the reproductive output of impacted colonies. Currently, most identified foraging areas are without specific management or protection status.

Variability of Sea Surface Temperature in Indonesia Based on Aqua Modis Satellite Data

Sea surface temperature (SST) is one of the oceanographic factor in seawater. Its value depends on several factors. In indonesia, SST value depend on season and location. The aims of this study are to analyze the spatial and temporal variability of SST using 10-years (2007-2016) Aqua Modis satellite data. The result shows that the average of SST in Indonesia ranges from 27 – 31 °C depending on location. SST in equator area range from 30 – 31 °C and in nonequator area range from 27 – 30 °C. Monthly and seasonal variation of SST also show different value for each area in the indonesian region.

Variability of Sea Surface Temperature in Indonesia Based on Aqua Modis Satellite Data

Sea surface temperature (SST) is one of the oceanographic factor in seawater. Its value depends on several factors. In indonesia, SST value depend on season and location. The aims of this study are to analyze the spatial and temporal variability of SST using 10-years (2007-2016) Aqua Modis satellite data. The result shows that the average of SST in Indonesia ranges from 27 – 31 °C depending on location. SST in equator area range from 30 – 31 °C and in nonequator area range from 27 – 30 °C. Monthly and seasonal variation of SST also show different value for each area in the indonesian region.

North Atlantic Oscillation drives the annual occurrence of an isolated, peripheral population of the brown seaweed Fucus guiryi in the Western Mediterranean Sea.

The canopy-forming, intertidal brown (Phaeophyceae) seaweed Fucus guiryi is distributed along the cold-temperate and warm-temperate coasts of Europe and North Africa. Curiously, an isolated population develops at Punta Calaburras (Alboran Sea, Western Mediterranean) but thalli are not present in midsummer every year, unlike the closest (ca. 80 km), perennial populations at the Strait of Gibraltar. The persistence of the alga at Punta Calaburras could be due to the growth of resilient, microscopic stages as well as the arrival of few–celled stages originating from neighbouring localities, and transported by the permanent Atlantic Jet flowing from the Atlantic Ocean into the Mediterranean. A twenty-six year time series (from 1990 to 2015) of midsummer occurrence of F. guiryi thalli at Punta Calaburras has been analysed by correlating with oceanographic (sea surface temperature, an estimator of the Atlantic Jet power) and climatic factors (air temperature, rainfall, and North Atlantic Oscillation –NAO-, and Arctic Oscillation –AO- indexes). The midsummer occurrence of thalli clustered from 1990–1994 and 1999–2004, with sporadic occurrences in 2006 and 2011. Binary logistic regression showed that the occurrence of thalli at Punta Calaburras in midsummer is favoured under positive NAO index from April to June. It has been hypothesized that isolated population of F. guiryi should show greater stress than their congeners of permanent populations, and to this end, two approaches were used to evaluate stress: one based on the integrated response during ontogeny (developmental instability, based on measurements of the fractal branching pattern of algal thalli) and another based on the photosynthetic response. Although significant differences were detected in photosynthetic quantum yield and water loss under emersion conditions, with thalli from Punta Calaburras being more affected by emersion than those from Tarifa, the developmental instability showed that the population from Tarifa suffers higher stress during ontogeny than that from Punta Calaburras. In conclusion, this study demonstrates the teleconnection between atmospheric oscillations and survival and proliferation of marine macroalgae.

Comparative population genetic study of an important marine parasite from New Zealand flat oysters

The comparative genetic structure of hosts and parasites can reveal constraints acting on parasite dispersal among host populations and the evolution of local adaptation. We sampled New Zealand flat oysters Ostrea chilensis from 12 sites throughout New Zealand to (1) determine the distribution and prevalence of the haplosporidian parasites Bonamia exitiosa and B. ostreae, and (2) test for congruent patterns of host and parasite genetic structure. B. exitiosa was detected at three sites: Hauraki Gulf (5% prevalence), Marlborough Sounds (30%), and Foveaux Strait (7%), whereas B. ostreae was only detected in the Marlborough Sounds (37%). Using nuclear internal transcribed spacer (ITS) rDNA sequences of B. exitiosa, as well as mitochondrial cytochrome c oxidase subunit 1 gene (CO1) sequences of O. chilensis from the same sites plus other key O. chilensis growing areas (Tasman Bay and Chatham Islands), we compared the genetic structure of host and parasite. B. exitiosa displayed genetic structure across all three sites which were reflected in populations of O. chilensis except for gene flow between Tasman Bay-Marlborough Sounds-Chatham Islands. The observed patterns reflect the host specificity of Bonamia parasites and the limited dispersal capability of oysters. O. chilensis may experience long distance dispersal which is likely influenced by oceanographic factors. Nonetheless, a failure to detect Bonamia parasites among genetically connected O. chilensis populations suggests natural long distance co-dispersal of Bonamia parasites with O. chilensis is unlikely. Instead, the dispersal of Bonamia parasites is likely influenced by anthropogenic factors.

The growth of finfish in global open-ocean aquaculture under climate change.

Aquaculture production is projected to expand from land-based operations to the open ocean as demand for seafood grows and competition increases for inputs to land-based aquaculture, such as freshwater and suitable land. In contrast to land-based production, open-ocean aquaculture is constrained by oceanographic factors, such as current speeds and seawater temperature, which are dynamic in time and space, and cannot easily be controlled. As such, the potential for offshore aquaculture to increase seafood production is tied to the physical state of the oceans. We employ a novel spatial model to estimate the potential of open-ocean finfish aquaculture globally, given physical, biological and technological constraints. Finfish growth potential for three common aquaculture species representing different thermal guilds-Atlantic salmon (Salmo salar), gilthead seabream (Sparus aurata) and cobia (Rachycentron canadum)-is compared across species and regions and with climate change, based on outputs of a high-resolution global climate model. Globally, there are ample areas that are physically suitable for fish growth and potential expansion of the nascent aquaculture industry. The effects of climate change are heterogeneous across species and regions, but areas with existing aquaculture industries are likely to see increases in growth rates. In areas where climate change results in reduced growth rates, adaptation measures, such as selective breeding, can probably offset potential production losses.

Impacts of oceanographic factors on interannual variability of the winter-spring cohort of neon flying squid abundance in the Northwest Pacific Ocean

The neon flying squid Ommastrephes bartramii is an economically important species in the Northwest Pacific Ocean. The life cycle of O. bartramii is highly susceptible to climatic and oceanic factors. In this study, we have examined the impacts of climate variability and local biophysical environments on the interannual variability of the abundance of the western winter-spring cohort of O. bartramii over the period of 1995–2011. The results showed that the squid had experienced alternant positive and negative Pacific Decadal Oscillation (PDO) over the past 17 years during which five El Nino and eight La Nina events occurred. The catch per unit effort (CPUE) was positively correlated with the PDO index (PDOI) at a one-year time lag. An abnormally warm temperature during the La Nina years over the positive PDO phase provided favorable oceanographic conditions for the habitats of O. bartramii, whereas a lower temperature on the fishing ground during the El Nino years over the negative PDO phase generally corresponded to a low CPUE. The same correlation was also found between CPUE and Chl a concentration anomaly. A possible explanation was proposed that the CPUE was likely related to the climateinduced variability of the large-scale circulation in the Northwest Pacific Ocean: high squid abundance often occurred in a year with a significant northward meander of the Kuroshio Current. The Kuroshio Current advected the warmer and food-rich waters into the fishing ground, and multiple meso-scale eddies arising from current instability enhanced the food retention on the fishing ground, all of which were favorable for the life stage development of the western squid stocks. Our results help better understand the potential process that the climatic and oceanographic factors affect the abundance of the winter-spring cohort of O. bartramii in the Northwest Pacific Ocean.

Producing distribution maps for informing ecosystem-based fisheries management using a comprehensive survey database and spatio-temporal models

Abstract Ecosystem-based fisheries-management (EBFM) is increasingly used in the United States (U.S.), including in the Gulf of Mexico (GOM). Producing distribution maps for marine organisms is a critical step in the implementation of EBFM. In particular, distribution maps are important inputs for many spatially-explicit ecosystem models, such as OSMOSE models, as well as for biophysical models used to predict annual recruitment anomalies due to oceanographic factors. In this study, we applied a recently proposed statistical modelling framework to produce distribution maps for: (i) younger juveniles (ages 0–1) of red snapper (Lutjanus campechanus), red grouper (Epinephelus morio), and gag (Mycteroperca microlepis), so as to be able to define the potential larval settlement areas of the three species in a biophysical model; and (ii) the functional groups and life stages represented in the OSMOSE model of the West Florida Shelf (“OSMOSE-WFS”). This statistical modelling framework consists of: (i) compiling a large database blending all of the encounter/non-encounter data of the GOM collected by the fisheries-independent and fisheries-dependent surveys using random sampling schemes, referred to as the “comprehensive survey database;” (ii) employing the comprehensive survey database to fit spatio-temporal binomial generalized linear mixed models (GLMMs) that integrate the confounding effects of survey and year; and (iii) using the predictions of the fitted spatio-temporal binomial GLMMs to generate distribution maps. This large endeavour allowed us to produce distribution maps for younger juveniles of red snapper, red grouper and gag and nearly all of the other functional groups and life stages represented in OSMOSE-WFS, at different seasons. Using Pearson residuals, the probabilities of encounter predicted by all spatio-temporal binomial GLMMs were demonstrated to be reasonable. Moreover, the results obtained for younger juvenile fish concur with the literature, provide additional insights into the spatial distribution patterns of these life stages, and highlight important future research avenues.

A global classification of coastal flood hazard climates associated with large-scale oceanographic forcing

Coastal communities throughout the world are exposed to numerous and increasing threats, such as coastal flooding and erosion, saltwater intrusion and wetland degradation. Here, we present the first global-scale analysis of the main drivers of coastal flooding due to large-scale oceanographic factors. Given the large dimensionality of the problem (e.g. spatiotemporal variability in flood magnitude and the relative influence of waves, tides and surge levels), we have performed a computer-based classification to identify geographical areas with homogeneous climates. Results show that 75% of coastal regions around the globe have the potential for very large flooding events with low probabilities (unbounded tails), 82% are tide-dominated, and almost 49% are highly susceptible to increases in flooding frequency due to sea-level rise.

The Holocene Labrador Current: Changing linkages to atmospheric and oceanographic forcing factors

The role of Labrador Current (LC) in providing freshwater to the North Atlantic and hence modulating the Atlantic meridional overturning circulation (AMOC) has been debated with very few data. This study provides the first data on the relative speed of the LC for the past 9.2 ka using mean size of the sortable silt of sediments as a proxy from a mid-shelf basin in the western Labrador Sea. LC speed progressively intensified from 9.2–5 ka, during which two meltwater events had minor influence. The LC was fastest between 5 ka and 3.1 ka and gradually weakened after 3.1 ka. The mean size of the sortable silt data shows overall co-variations with similar existing data from deep-water areas of the greater North Atlantic, suggesting an overarching link that modulates changes in both the near-surface and deep North Atlantic. A dynamical link between the LC and AMOC vigor is hypothesized in which high meltwater discharge in the Labrador Sea oriented the subpolar gyre (SPG) more North-South (meridional), weakening the SPG, and thus decelerating the upper limb of the AMOC. Conversely, reduction in LC transport during the late Holocene, due to the greater export of sea ice, oriented the SPG more East-West.

Flyingfish (Exocoetidae) species diversity and habitats in the eastern tropical Pacific Ocean.

Flyingfishes are large enough to eat zooplankton, small enough to be consumed by top predators, and therefore form a central mid-trophic component of tropical epipelagic marine food webs. Characterizing patterns of flyingfish abundance, distribution, and habitat preference have important implications for understanding both localized and generalized functions of marine ecosystems. The eastern tropical Pacific Ocean (ETP) supports many flyingfish species and their predators, yet no studies to date have identified oceanographic factors that define flyingfish habitats or estimate species richness and diversity at broad taxonomic and geographic scales. In this study, we analyzed 11,125 flyingfish representing 25 species and all 7 named genera, collected from the ETP over a 21-year period. We applied spatially-explicit analysis methods (ARCGIS, DIVA-GIS, MAXENT) and compared specimen locality data to remotely-sensed oceanographic data, and previously described oceanographic partitions. Our results show that Exocoetus is the most abundant genus (49%), and E. monocirrhus the most abundant species (32%) of flyingfishes in the ETP. Mean sea surface temperature was most important for defining flyingfish habitats (19.2-41.7%) and species richness (highest in the North Equatorial Current). Additionally, flyingfish species diversity was found to be highest in coastal regions of the study area (Shannon indices > 1.5). Together, these results provide unprecedented characterizations of a mid-trophic epipelagic community in an economically valuable region during a time when sea surface temperatures are predicted to increase as a result of global climate change.

Distribución y abundancia espacial y temporal de Stomolophus meleagris (Rhizostomae: Stomolophidae) en un sistema lagunar del sur del Golfo de México

The scyphomedusae feed mainly on microscopic crustaceans, eggs and fish larvae, molluscs and some other jellyfishes. The distribution and abundance of the scyphomedusae has an economic and ecological impact as they are predators that have an influence on the population dynamics of other fisheries. This investigation took place in the lagoon system ‘Arrastradero-Redonda’, Tabasco, from September 2013 to August 2014, with the purpose to provide information on the distribution, and spatial and temporal abundance of Stomolophus meleagris; along with its relation to environmental parameters. A total of 10 stations were defined and biological samples were taken on a monthly basis during this annual cycle. For this purpose, three pulls with a beach seine monofilament (20m long by 3m height, mesh opening 1.5 cm, 5 to 10 minutes) per station were made within a 1 km2 area. Information obtained was used to calculate the fishing efficiency analysis (CPUE con org./Evaluated Area Unit) and to determine the relationship with the environmental parameters. Our results showed that the abundance in the stations 1 to 3 was from 7 to 19 org./km2 from April to August 2014; less organisms were observed in stations 6 to 10 (an average of 1 org./km2) from October 2013 to March 2014. The multiple correlation steps analysis indicated that there is a strong association between the CPUE and some environmental investigated variables, and a 70.9 % variability of the data was observed. The salinity resulted the most important variable because it determined a 64.3 % of variation; it was followed by the temperature with a 3.6 %; meanwhile, dissolved oxygen explained only the 2.9 %, this was mainly because within the area there are several geological, oceanographic and biological factors that favor the distribution of this species due to seawater contribution through the Tupilco bar. With the provided data with this investigation we were able to determine the fishery potential of this resource for Tabasco state. However, additional research is required to allow an extended quantification of this resource, to determine the commercial exploitation areas, and drive studies about reproductive and feeding habits, that may provide the necessary information to establish plans for sustainable use.

Spatial growth variability in marine fish: example from Northeast Pacific groundfish

Abstract Marine fish populations exist in a complex environment, with oceanographic and fisheries factors affecting their dynamics. It has been shown that life history characteristics of marine fish vary in space and time. We examined spatial variability in growth of eight groundfish species in the Northeast Pacific Ocean to identify shared spatial patterns and hypothesize about common mechanisms behind them. Growth parameters were estimated in different areas over the latitudinal range of the species, and several hypotheses were tested as to how these parameters vary along the US west coast. Clear differences in spatial growth variability emerged among the species examined. Shelf species exhibit the highest growth rate between Cape Blanco and Cape Mendocino, which may, in part, be attributed to area-specific upwelling patterns in the California Current ecosystem, when nutrient-rich deep water is brought to the surface south of Cape Blanco and is uniquely distributed throughout this area, providing favourable conditions for primary productivity. Slope species showed a cline in asymptotic size (L∞), with L∞ increasing from south to north. This cline, previously attributed to fishery removals, also fits a specific case of the widely described Bergmann’s rule, and we explore specific potential ecological mechanisms behind this relationship.

Modeling Nonresident Seabird Foraging Distributions to Inform Ocean Zoning in Central California.

Seabird aggregations at sea have been shown to be associated with concentrations of prey. Previous research identified Central California as a highly used foraging area for seabirds, with locally breeding seabirds foraging close to their colonies on Southeast Farallon Island. Herein, we focus on nonresident (i.e. non-locally breeding) seabird species off of Central California. We hypothesized that high-use foraging areas for nonresident seabirds would be influenced by oceanographic and bathymetric factors and that spatial and temporal distributions would be similar within planktivorous and generalist foraging guilds but would differ between them. With data collected by the Applied California Current Ecosystem Studies (ACCESS) partnership during cruises between April and October from 2004–2013, we developed generalized linear models to identify high-use foraging areas for each of six nonresident seabird species. The four generalist species are Phoebastria nigripes (black-footed albatross), Ardenna griseus (sooty shearwater), Ardenna creatopus (pink-footed shearwater), and Fulmarus glacialis (northern fulmar). The two planktivorous species are Phalaropus lobatus (red-necked phalarope) and Phalaropus fulicarius (red phalarope). Sea surface temperature was significant for generalist species and sea surface salinity was important for planktivorous species. The distance to the 200-m isobath was significant in five of six models, Pacific Decadal Oscillation with a 3-month lag in four models, and sea surface fluorescence, the distance to Cordell Bank, and depth in three models. We did not find statistically significant differences between distributions of individual seabird species within a foraging guild or between guilds, with the exception of the sooty shearwater. Model results for a multi-use seabird foraging area highlighted the continental shelf break, particularly within the vicinity of Cordell Bank, as the highest use areas as did Marxan prioritization. Our research methods can be implemented elsewhere to identify critical habitat that needs protection as human development pressures continue to expand to the ocean.

Detection of potential fishing zone for Pacific saury (Cololabis saira) using generalized additive model and remotely sensed data

To evaluate the effects of oceanographic conditions on the formation of the potential fishing zones for Pacific saury in western North Pacific, fishing locations of Pacific saury from Defense Meteorological Satellite Program/Operating Linescan System (DMSP/OLS) and satellite-based oceanographic information were used to construct species habitat models. A 2-level slicing method was used to identify the bright regions as actual fishing areas from OLS images, collected during the peak fishing season of Pacific saury in the North Pacific. Statistical metrics, including the significance of model terms, and reduction in the Akaike’s Information Criterion (AIC) were used as the bases for model selection. The selected model was then used to visualize the basin scale distributions of the Pacific saury habitat. The predicted potential fishing zones exhibited spatial correspondence with the fishing locations. The results from generalized additive model revealed that the Pacific saury habitat selection was significantly influenced by the SST ranges from 13-18°C, SSC ranges from 0.5-1.8 mg.m-3, SSHA ranges from 5-17 cm and EKE ranges from 700-1200 cm2s-2. Moreover, among the set of oceanographic factors examined, SST explained the smallest AIC and is thus, considered to be the most significant variable in the geographic distribution of Pacific saury.

Effects of environmental factors on the abundances of the basket stars Astrocaneum spinosum and Astrodictyum panamense (Ophiuroidea: Gorgonocephalidae) in the northern Gulf of California, Mexico

ABSTRACTGorgonocephalid ophiuroids, or basket stars, reside in diverse ecosystems of all oceans, but there is limited information on their basic ecology worldwide; therefore, this study provides the first detailed numerical analysis published to date of the abundances and spatial distributions of gorgonocephalids from the eastern Pacific Ocean. We analysed the relevance of geography (latitude, longitude), oceanographic factors (temperature, chlorophyll a concentration) and bottom type (coral, rock, sand, fleshy algae, coralline algae and turf) on the abundances of Astrocaneum spinosum and Astrodictyum panamense in Los Angeles Bay, Mexico (29°N, 113°W), in 2006–2007. Depth did not influence the number of individuals per census, but an elevated chlorophyll a concentration resulted in a higher abundance during the autumn (possibly the reproductive season of Astrodictyum panamense and Astrocaneum spinosum). The abundances of both species were positively linked to the presence of rocky bottoms and decreased in sandy areas. Additionally, the presence of live coral favoured the occurrence of Astrodictyum panamense, while high macroalgal cover decreased its abundance. The spatial distributions of both ophiuroids were aggregated at most sites, and they were always associated with different species of octocorals, which are abundant in the area. Astrocaneum spinosum is considered among the 30 most important invertebrates in the aquarium trade in Mexico; therefore, its permanence in the study area could be affected by excessive extractions.

Coast-wide recruitment dynamics of Olympia oysters reveal limited synchrony and multiple predictors of failure.

Recruitment of new propagules into a population can be a critical determinant of adult density. We examined recruitment dynamics in the Olympia oyster (Ostrea lurida), a species occurring almost entirely in estuaries. We investigated spatial scales of interannual synchrony across 37 sites in eight estuaries along 2,500km of Pacific North American coastline, predicting that high vs. low recruitment years would coincide among neighboring estuaries due to shared exposure to regional oceanographic factors. Such synchrony in recruitment has been found for many marine species and some migratory estuarine species, but has never been examined across estuaries in a species that can complete its entire life cycle within the same estuary. To inform ongoing restoration efforts for Olympia oysters, which have declined in abundance in many estuaries, we also investigated predictors of recruitment failure. We found striking contrasts in absolute recruitment rate and frequency of recruitment failure among sites, estuaries, and years. Although we found a positive relationship between upwelling and recruitment, there was little evidence of synchrony in recruitment among estuaries along the coast, and only limited synchrony of sites within estuaries, suggesting recruitment rates are affected more strongly by local dynamics within estuaries than by regional oceanographic factors operating at scales encompassing multiple estuaries. This highlights the importance of local wetland and watershed management for the demography of oysters, and perhaps other species that can complete their entire life cycle within estuaries. Estuaries with more homogeneous environmental conditions had greater synchrony among sites, and this led to the potential for estuary-wide failure when all sites had no recruitment in the same year. Environmental heterogeneity within estuaries may thus buffer against estuary-wide recruitment failure, analogous to the portfolio effect for diversity. Recruitment failure was correlated with lower summer water temperature, higher winter salinity, and shorter residence time: all indicators of stronger marine influence on estuaries. Recruitment failure was also more common in estuaries with limited networks of nearby adult oysters. Large existing oyster networks are thus of high conservation value, while estuaries that lack them would benefit from restoration efforts to increase the extent and connectivity of sites supporting oysters.

Rare earth elements of shallow-water articulated brachiopods: A bathymetric sensor

Variations in environmental physicochemical parameters result in corresponding changes in seawater rare earth element (REE) distributions. For an archive to be utilized in paleoceanographic and paleoenvironmental reconstructions, it should record these variations. Therefore, an archive's proxy potentiality should be assessed analogous to modern oceanic settings.Articulated brachiopods of several shallow water localities (<500m) of different water masses were evaluated for their REE contents. The affects of oceanographic factors such as depth, salinity, and temperature were investigated for REE uptake by the shells. Uptake of REE by dorsal and ventral valves of articulated shells are unequivocal, whereas shells of Thecideidines, the umbo region and primary layer of the Terebratulids are anomalous, and should be avoided. Water temperature and salinity appear to have minor to moderate impacts on the partition coefficients of REEs between seawater and brachiopod calcite.The mean REESN pattern of shallow-water brachiopods is significantly different from that of their deep-water counterparts, with lower enrichments in LREEs and MREEs, and depletion in HREEs. Depth exercises a major control on the LREE and MREE fractionation with a milder one on HREE fractionation. The Ce/Ce* anomaly is not affected by either of these parameters in shallow-water settings, but in deep settings the depth effect dominates. Due to the importance of depth on REE fractionation in the shells from shallow settings, their LREESN to HREESN ratios (L:H) were divided into six discrete intervals for the bathymetric sensor. The bathymetric sensor was applied to some fossils and whole rock in order to estimate their paleodepths. The evaluation was successful in placing the Permian Gyanyima, the Pennsylvanian Naco, Boggy and the Silurian Chicotte, Becscie and Jupiter Formations in shallow depths (<15–50m), which is consistent with their paleoenvironmental settings.