Climatic factors associated with phytoplankton community succession during and after the 1977 drought for the San Francisco Bay-Delta Estuary [abstract]

Principal coordinates analysis and multiple regression analysis were used to determine the environmental factors associated with the decline in phytoplankton production during and after the 1977 drought for the San Francisco Bay-Delta Estuary. Physical, chemical and biological data were collected semimonthly or monthly during the spring-summer between 1973 and 1982 from 15 sampling sites located throughout the Bay-Delta. A decline in phytoplankton community diversity and density during the 1977 drought and subsequent years (1978 through 1981) was described using principal coordinates analysis. The best multiple regression which described the changes in phytoplankton community succession contained the variables water temperature, wind velocity and ortho-phosphate concentration. Together these variables accounted for 61 percent of the variation in the phytoplankton community among years described by principal coordinates analysis. An increase in water temperature, wind velocity and ortho-phosphate concentration within the Bay-Delta, beginning in June 1976 and continuing through 1981, was demonstrated using weighted moving averages. From the strong association between phytoplankton community succession and climatic variables it was hypothesized that the decline in phytoplankton production during and after the 1977 drought was associated with climatic changes within the northeast Pacific.

An overview of 1000 years of tropical climatic variability from ice cores from the Andes of southern Peru [abstract]

EXTRACT (SEE PDF FOR FULL ABSTRACT): Each summer between 1976 and 1984 research was conducted on the Quelccaya Ice Cap with one central objective, to recover an ice core to bedrock from which an approximate 1000 year climatic history for tropical South America could be reconstructed. In 1983 that central objective was accomplished by recovering one core 155 meters in length containing 1350 years and a second core of 163.6 meters containing more than 1500 years of climatic history. ... The most significant climatic event in tropical South America over the last 1500 years was the "Little Ice Age" which is recorded between 1490 to 1880 A.D. in these ice core records. Records from the summit of the Quelccaya Ice Cap show that during the "Little Ice Age" period there was (1) a general increase in particulates (both insoluble and soluble, starting around 1490 A.D. and ending abruptly in 1880 A.D.; (2) an initial increase in net accumulation (1500-1720 A.D.) followed by a period of decreased net accumulation (1720-1860 A.D.); (3) more negative delta-O-18 values beginning in the 1520's and ending around 1880 A.D. The "Little Ice Age" event is evident as a perturbation in all five ice core parameters.

Tropical forest history of the Ecuadorian Andes over the last 34,000 years: preliminary results from pollen and oxygen isotope analyses of Trident 163-13 from the eastern equatorial Pacific [abstract]

EXTRACT (SEE PDF FOR FULL ABSTRACT): Pollen from the upper 2.75 m of a core taken 200 km west of the Golfo de Guayaquil, Ecuador (Trident 163-13, 3° S, 84° W, 3,000 m water depth) documents changes in Andean vegetation and climate of the Cordillera Occidental for ~17,000 years before and after the last glacial maximum.

Seasonal and interannual variation in juvenile salmonids and associated fish assemblage in open waters of the lower Columbia River estuary

The transition between freshwater and marine environments is associated with high mortality for juvenile anadromous salmonids, yet little is known about this critical period in many large rivers. To address this deficiency, we investigated the estuarine ecology of juvenile salmonids and their associated fish assemblage in open-water habitats of the lower Columbia River estuary during spring of 2007–10. For coho (Oncorhynchus kisutch), sockeye (O. nerka), chum (O. keta), and yearling (age 1.0) Chinook (O. tshawytscha) salmon, and steelhead (O. mykiss), we observed a consistent seasonal pattern characterized by extremely low abundances in mid-April, maximum abundances in May, and near absence by late June. Subyearling (age 0.0) Chinook salmon were most abundant in late June. Although we observed interannual variation in the presence, abundance, and size of juvenile salmonids, no single year was exceptional across all species-and-age classes. We estimated that >90% of juvenile Chinook and coho salmon and steelhead were of hatchery origin, a rate higher than previously reported. In contrast to juvenile salmonids, the abundance and composition of the greater estuarine fish assemblage, of which juvenile salmon were minor members, were extremely variable and likely responding to dynamic physical conditions in the estuary. Comparisons with studies conducted 3 decades earlier suggest striking changes in the estuarine fish assemblage—changes that have unknown but potentially important consequences for juvenile salmon in the Columbia River estuary.

Distribution of ommastrephid paralarvae in the eastern tropical Pacific

Jumbo squid (Dosidicus gigas) and purpleback squid (Sthenoteuthis oualaniensis) (Teuthida: Ommastrephidae) are thought to spawn in the eastern tropical Pacific. We used 10 years of plankton tow and oceanographic data collected in this region to examine the reproductive habits of these 2 ecologically important squid. Paralarvae of jumbo squid and purpleback squid were found in 781 of 1438 plankton samples from surface and oblique tows conducted by the Southwest Fisheries Science Center (NOAA) in the eastern tropical Pacific over the 8-year period of 1998–2006. Paralarvae were far more abundant in surface tows (maximum: 1588 individuals) than in oblique tows (maximum: 64 individuals). A generalized linear model analysis revealed sea-surface temperature as the strongest environmental predictor of paralarval presence in both surface and oblique tows; the likelihood of paralarval presence increases with increasing temperature. We used molecular techniques to identify paralarvae from 37 oblique tows to species level and found that the purpleback squid was more abundant than the jumbo squid (81 versus 16 individuals).

Migratory and within-estuary behaviors of adult Summer Flounder (Paralichthys dentatus) in a lagoon system of the southern mid-Atlantic Bight

We monitored the movements of 45 adult Summer Flounder (Paralichthys dentatus) between June 2007 and July 2008 through the use of passive acoustic telemetry to elucidate migratory and within-estuary behaviors in a lagoon system of the southern mid-Atlantic Bight. Between 8 June and 10 October 2007, fish resided primarily in the deeper (>3 m) regions of the system and exhibited low levels of large-scale (100s of meters) activity. Mean residence time within this estuarine lagoon system was conservatively estimated to be 130 days (range: 18–223 days), which is 1.5 times longer than the residence time previously reported for Summer Flounder in a similar estuarine habitat ~250 km to the north. The majority of fish remained within the lagoon system until mid-October, although some fish dispersed earlier and some of them appeared to disperse temporarily (i.e., exited the system for at least 14 consecutive days before returning). Larger fish were more likely to disperse before mid-October than smaller fish and may have moved to other estuaries or the inner continental shelf. Fish that dispersed after mid-October were more likely to return to the lagoon system the following spring than were fish that dispersed before mid-October. In 2008, fish returned to the system between 7 February and 7 April. Dispersals and returns most closely followed seasonal changes in mean water temperature, but photoperiod and other factors also may have played a role in large-scale movements of Summer Flounder.

Population genetics of Cobia (Rachycentron canadum): implications for fishery management along the coast of the southeastern United States

Cobia (Rachycentron canadum) is a pelagic, migratory species with a transoceanic distribution in tropical and subtropical waters. Recreational fishing pressure on Cobia in the United States has increased substantially during the last decade, especially in areas of its annual inshore aggregations, making this species potentially susceptible to overfishing. Although Cobia along the Atlantic and Gulf coasts of the southeastern United States are currently managed as a single fishery, the genetic composition of Cobias in these areas is unclear. On the basis of a robust microsatellite data set from collections along the U.S. Atlantic coast (2008–09), offshore groups were genetically homogenous. However, the 2 sampled inshore aggregations (South Carolina and Virginia) were genetically distinct from each other, as well as from the offshore group. The recapture of stocked fish within their release estuary 2 years after release indicates that some degree of estuarine fidelity occurs within these inshore aggregations and supports the detection of their unique genetic structure at the population level. These results complement the observed high site fidelity of Cobias in South Carolina and support a recent study that confirms that Cobia spawn in the inshore aggregations. Our increased understanding of Cobia life history will be beneficial for determining the appropriate scale of fishery management for Cobia.

Habitat availability and heterogeneity and the Indo-Pacific warm pool as predictors of marine species richness in the tropical Indo-Pacific

Range overlap patterns were observed in a dataset of 10,446 expert-derived marine species distribution maps, including 8,295 coastal fishes, 1,212 invertebrates (crustaceans and molluscs), 820 reef-building corals, 50 seagrasses and 69 mangroves. Distributions of tropical Indo-Pacific shore fishes revealed a concentration of species richness in the northern apex and central region of the Coral Triangle epicenter of marine biodiversity. This pattern was supported by distributions of invertebrates and habitat-forming primary producers. Habitat availability, heterogeneity and sea surface temperatures were highly correlated with species richness across spatial grains ranging from 23,000 to 5,100,000 km2 with and without correction for autocorrelation. The consistent retention of habitat variables in our predictive models supports the area of refuge hypothesis which posits reduced extinction rates in the Coral Triangle. This does not preclude support for a center of origin hypothesis that suggests increased speciation in the region may contribute to species richness. In addition, consistent retention of sea surface temperatures in models suggests that available kinetic energy may also be an important factor in shaping patterns of marine species richness. Kinetic energy may hasten rates of both extinction and speciation. The position of the Indo-Pacific Warm Pool to the east of the Coral Triangle in central Oceania and a pattern of increasing species richness from this region into the central and northern parts of the Coral Triangle suggests peripheral speciation with enhanced survival in the cooler parts of the Coral Triangle that also have highly concentrated available habitat. These results indicate that conservation of habitat availability and heterogeneity is important to reduce extinction and that changes in sea surface temperatures may influence the evolutionary potential of the region.

Contrasting seasonal patterns in dimethylsulfide, dimethylsulfoniopropionate, and chlorophyll a in a shallow North Carolina estuary and the Sargasso Sea

Time series measurements of dimethylsulfide (DMS), particulate dimethylsulfoniopropionate (DMSPp), chlorophyll a (chl a), algal pigments, major nutrients, and the potential activity of DMSP lyase enzymes were made over a 2 yr period (6 March 2003 to 28 March 2005) near the mouth of the shallow, tidally mixed Newport River estuary, North Carolina, USA. DMSPp had a mean of 43 ± 20 nM (range = 10.5 to 141 nM, n = 85) and DMS a mean of 2.7 ± 1.2 nM (range = 0.9 to 7.0 nM). The mean DMS in Gallants Channel was not significantly different from that measured in the Sargasso Sea near Bermuda during a previous 3 yr time series study (2.4 ± 1.5 nM), despite there being a 43-fold higher mean chl a concentration (4.9 ± 2.4 µg l–1) at the coastal site. In winter, DMS was low and chl a was high in the surface waters of the Sargasso Sea, while the opposite was true at the coastal site. Consequently, DMS concentrations per unit algal chl a were on average 170 times higher in the Sargasso Sea than at the coastal site during the summer, but only 7 times higher during the winter. The much higher chl a-specific DMS concentrations at the oceanic site during the summer were linked to higher ratios of intracellular DMSP substrate and DMSP lyase enzyme per unit chl a. These differences in turn appear to be linked to large differences in nutrient concentrations and solar UV stress at the 2 sites and to associated differences in the composition of algal assemblages and physiological acclimation of algal cells.

Characterizing Jobos Bay, Puerto Rico: a watershed modeling analysis and monitoring plan

Land-based pollution is commonly identified as a major contributor to the observed deterioration of shallow-water coral reef ecosystem health. Human activity on the coastal landscape often induces nutrient enrichment, hypoxia, harmful algal blooms, toxic contamination and other stressors that have degraded the quality of coastal waters. Coral reef ecosystems throughout Puerto Rico, including Jobos Bay, are under threat from coastal land uses such as urban development, industry and agriculture. The objectives of this report were two-fold: 1. To identify potentially harmful land use activities to the benthic habitats of Jobos Bay, and 2. To describe a monitoring plan for Jobos Bay designed to assess the impacts of conservation practices implemented on the watershed. This characterization is a component of the partnership between the U.S. Department of Agriculture (USDA) and the National Oceanic and Atmospheric Administration (NOAA) established by the Conservation Effects Assessment Project (CEAP) in Jobos Bay. CEAP is a multi-agency effort to quantify the environmental benefits of conservation practices used by private landowners participating in USDA programs. The Jobos Bay watershed, located in southeastern Puerto Rico, was selected as the first tropical CEAP Special Emphasis Watershed (SEW). Both USDA and NOAA use their respective expertise in terrestrial and marine environments to model and monitor Jobos Bay resources. This report documents NOAA activities conducted in the first year of the three-year CEAP effort in Jobos Bay. Chapter 1 provides a brief overview of the project and background information on Jobos Bay and its watershed. Chapter 2 implements NOAA’s Summit to Sea approach to summarize the existing resource conditions on the watershed and in the estuary. Summit to Sea uses a GIS-based procedure that links patterns of land use in coastal watersheds to sediment and pollutant loading predictions at the interface between terrestrial and marine environments. The outcome of Summit to Sea analysis is an inventory of coastal land use and predicted pollution threats, consisting of spatial data and descriptive statistics, which allows for better management of coral reef ecosystems. Chapters 3 and 4 describe the monitoring plan to assess the ecological response to conservation practices established by USDA on the watershed. Jobos Bay is the second largest estuary in Puerto Rico, but has more than three times the shoreline of any other estuarine area on the island. It is a natural harbor protected from offshore wind and waves by a series of mangrove islands and the Punta Pozuelo peninsula. The Jobos Bay marine ecosystem includes 48 km² of mangrove, seagrass, coral reef and other habitat types that span both intertidal and subtidal areas. Mapping of Jobos Bay revealed 10 different benthic habitats of varying prevalence, and a large area of unknown bottom type covering 38% of the entire bay. Of the known benthic habitats, submerged aquatic vegetation, primarily seagrass, is the most common bottom type, covering slightly less than 30% of the bay. Mangroves are the dominant shoreline feature, while coral reefs comprise only 4% of the total benthic habitat. However, coral reefs are some of the most productive habitats found in Jobos Bay, and provide important habitat and nursery grounds for fish and invertebrates of commercial and recreational value.

Annual estimates of the unobserved incidental kill of pantropical spotted dolphin (Stenella attenuata attenuata) calves in the tuna purse-seine fishery of the eastern tropical Pacific

We estimated the total number of pantropical spotted dolphin (Stenella attenuata) mothers killed without their calves (“calf deficit”) in all tuna purse-seine sets from 1973– 90 and 1996–2000 in the eastern tropical Pacific. Estimates were based on a tally of the mothers killed as reported by color pattern and gender, several color-pattern-based frequency tables, and a weaning model. Over the time series, there was a decrease in the calf deficit from approximately 2800 for the western-southern stock and 5000 in the northeastern stock to about 60 missing calves per year. The mean deficit per set decreased from approximately 1.5 missing calves per set in the mid-1970s to 0.01 per set in the late-1990s. Over the time series examined, from 75% to 95% of the lactating females killed were killed without a calf. Under the assumption that these orphaned calves did not survive without their mothers, this calf deficit represents an approximately 14% increase in the reported kill of calves, which is relatively constant across the years examined. Because the calf deficit as we have defined it is based on the kill of mothers, the total number of missing calves that we estimate is potentially an underestimate of the actual number killed. Further research on the mechanism by which separation of mother and calf occurs is required to obtain better estimates of the unobserved kill of dolphin calves in this fishery.