National Ocean Service

About: National Ocean Service is a government organization based out in Silver Spring, Maryland, United States. It is known for research contribution in the topics: Algal bloom & Population. The organization has 500 authors who have published 643 publications receiving 46096 citations.

Colonization, succession, and nutrition of macrobenthic assemblages in a restored wetland at Tijuana Estuary, California

Abstract: Modes of colonization, the successional trajectory, and trophic recovery of a macrofaunal community were analyzed over 19 months in the Friendship marsh, a 20-acre restored wetland in Tijuana Estuary, California. Traditional techniques for quantifying macrofaunal communities were combined with emerging stable isotopic approaches for evaluation of trophic recovery, making comparisons with a nearby natural Spartina foliosa habitat. Life history-based predictions successfully identified major colonization modes, although most taxa employed a variety of tactics for colonizing the restored marsh. The presence of S. foliosa did not seem to affect macrofaunal colonization or succession at the scale of this study. However, soil organic matter content in the restored marsh was positively correlated with insect densities, and high initial salinities may have limited the success of early colonists. Total macrofaunal densities recovered to natural marsh levels after 14 months and diversity, measured as species richness and the Shannon index ( H ′), was comparable to the natural marsh by 19 months. Some compositional disparities between the natural and created communities persisted after 19 months, including lower percentages of surface-feeding polychaetes ( Polydora spp.) and higher percentages of dipteran insects and turbellarians in the Friendship marsh. As surficial structural similarity of infaunal communities between the Friendship and natural habitat was achieved, isotopic analyses revealed a simultaneous trajectory towards recovery of trophic structure. Enriched δ 13 C signatures of benthic microalgae and infauna, observed in the restored marsh shortly after establishment compared to natural Spartina habitat, recovered after 19 months. However, the depletion in δ 15 N signatures of macrofauna in the Friendship marsh indicated consumption of microalgae, particularly nitrogen-fixing cyanobacteria, while macroalgae and Spartina made a larger contribution to macrofaunal diets in the natural habitat. Future successional studies must continue to develop and employ novel combinations of techniques for evaluating structural and functional recovery of disturbed and created habitats.

Benthic structure and cryptic mortality in a Caribbean mesophotic coral reef bank system, the Hind Bank Marine Conservation District, U.S. Virgin Islands

Abstract: Coral reef banks may form an important component of mesophotic coral ecosystems (MCEs) in the Caribbean, but remain poorly explored relative to shallower reefs and mesophotic habitats on slopes and walls. Consequently, the processes structuring mesophotic coral reef communities are not well understood, particularly the role of disturbance. A large and regionally important mesophotic system, the Hind Bank Marine Conservation District (MCD), St. Thomas, USVI, was systematically surveyed. Data were used to construct a comprehensive benthic habitat map for the MCD, describe the abiotic and biotic components of the benthos among habitats, and investigate patterns of coral health among habitats. Two-thirds of the MCD (23.6 km2) was found to be dense coral reef (Coral Cover = 24.1%) dominated by the Montastraea annularis species complex. Coral reef ecosystems were topographically complex, but could be classified into distinct habitat types, including high coral banks (35.8% of the MCD) and two large novel coral reef habitat types corresponding to an extremely flat basin (18%) and a highly rugose hillock basin (6.5%), containing thousands of coral knolls (2–10 m high). An extreme disease event with undescribed signs of mortality occurred on 47% of coral reefs and reached a high prevalence in affected areas (42.4% ± 6.3 SE, N = 26). The disease was significantly clustered in the basin habitats of the western MCD (global Moran’s I = 0.32, P < 0.01). Observations of the spatial pattern suggested that the driver was specific to the basin habitats and may have been caused by a coherent abiotic event.

Relationships Between Bacteria and Harmful Algae

Abstract: The interactions of harmful algal (HA) species with their physico-chemical and biological environments ultimately determine their abundance and distribution. While an algal taxon’s physiological tolerance limits (e.g., temperature, salinity, light) and intrinsic phenotypic traits (e.g., growth rate, nutrient uptake, vertical migration) largely define its ecological niche, relationships with the biological components of an ecosystem (e.g., grazers, microbes, pathogens, competing algal species) play a critical role in its ability to achieve concentrations that lead to the many negative impacts characterizing harmful species. A biological factor of potentially great significance in regulating the population and even toxin dynamics of HA that has received increasing yet comparatively little attention to date is their relationship with the ubiquitous and diverse bacterial community. These microbes, which exist as free-living forms as well as securely attached to algal cells, occasionally with a high degree of taxonomic specificity, have now been demonstrated to modulate (either positively or negatively) algal growth rates and transitions between life history stages, influence toxin production, and even induce the rapid lysis of algal cells. Previous reviews of this topic (e.g., Doucette 1995; Doucette et al. 1998) described an exciting, emerging field in which molecular-based approaches were just beginning to supplement traditional bacteriological techniques, yielding new insights into the nature and ecological implications of bacterialalgal interactions. During the intervening time, continued application of molecular techniques, novel experimental methods, and targeted studies of natural bacterial communities have contributed valuable details of the relationships between bacteria and HA that will be the focus of this chapter.

Trends in Indicators of Eutrophication in Western Long Island Sound and the Hudson-Raritan Estuary

Abstract: Significant improvements in water quality have been observed for several decades throughout much of the Hudson-Raritan Estuary, primarily as a result of regional abatement of municipal and industrial discharges. These improvements include area-wide, order-of-magnitude reductions in ambient coliform concentrations and significant increases in dissolved oxygen (DO) concentrations. In contrast to these improvements, DO in bottom waters of the western Long Island Sound (WLIS) appears to have decreased in the last two decades. Although there is no consensus as to why hypoxia in WLIS may have recently become more severe, several related hypotheses have been suggested, including an increase in eutrophication, increased density stratification, and changes in wastewater loads. To determine if eutrophication has increased in WLIS, trends in several indicators of eutrophication were examined from a long-term water quality data set. Since the mid-1980s surface DO supersaturation has increased, bottom minimum DO has decreased, and vertical DO stratification has increased in WLIS. Other areas of the Hudson-Raritan Estuary, such as Jamaica Bay and Raritan Bay, exhibit similar evidence of declining water quality and may be experiencing increasing eutrophication. Temporal changes in vertical density stratification indicate that surface to bottom temperature differences have increased to a greater extent and have had a more significant impact on bottom DO depletion in WLIS than in the shallower Jamaica Bay and Raritan Bay. Additional factors contributing to the observed decline in water quality include recent changes in wastewater loads and possible increases in upstream and nonpoint source loads.