Endangered right whales enhance primary productivity in the bay of fundy

This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Marine mammals have recently been documented as important facilitators of rapid and efficient nutrient recycling in coastal and offshore waters. Whales enhance phytoplankton nutrition by releasing fecal plumes near the surface after feeding and by migrating from highly productive, high-latitude feeding areas to low-latitude nutrient-poor calving areas. In this study, we measured NH4 + and PO4 3- release rates from the feces of North Atlantic right whales (Eubalaena glacialis), a highly endangered baleen whale. Samples for this species were primarily collected by locating aggregations of whales in surface- Active groups (SAGs), which typically consist of a central female surrounded by males competing for sexual activity. When freshly collected feces were incubated in seawater, high initial rates of N release were generally observed, which decreased to near zero within 24 hours of sampling, a pattern that is consistent with the active role of gut microflora on fecal particles. We estimate that at least 10% of particulate N in whale feces becomes available as NH4 + within 24 hours of defecation. Phosphorous was also abundant in fecal samples: Initial release rates of PO4 3- were higher than for NH4 +, yielding low N/P nutrient ratios over the course of our experiments. The rate of PO4 3- release was thus more than sufficient to preclude the possibility that nitrogenous nutrients supplied by whales would lead to phytoplankton production limited by P availability. Phytoplankton growth experiments indicated that NH4 + released from whale feces enhance productivity, as would be expected, with no evidence that fecal metabolites suppress growth. Although North Atlantic right whales are currently rare (approximately 450 individuals), they once numbered about 14,000 and likely played a substantial role in recycling nutrients in areas where they gathered to feed and mate. Even though the NH4 + released from fresh whale fecal material is a small fraction of total whale fecal nitrogen, and recognizing the fact that the additional nitrogen released in whale urine would be difficult to measure in a field study, the results of this study support the idea that the distinctive isotopic signature of the released NH4 + could be used to provide a conservative estimate of the contribution of the whale pump to primary productivity in coastal regions where whales congregate

Four Regional Marine Biodiversity Studies: Approaches and Contributions to Ecosystem-Based Management

We compare objectives and approaches of four regional studies of marine biodiversity: Gulf of Maine Area Census of Marine Life, Baltic Sea History of Marine Animal Populations, Great Barrier Reef Seabed Biodiversity Project, and Gulf of Mexico Biodiversity Project. Each program was designed as an "ecosystem" scale but was created independently and executed differently. Each lasted 8 to 10 years, including several years to refine program objectives, raise funding, and develop research networks. All resulted in improved baseline data and in new, or revised, data systems. Each contributed to the creation or evolution of interdisciplinary teams, and to regional, national, or international science-management linkages. To date, there have been differing extents of delivery and use of scientific information to and by management, with greatest integration by the program designed around specific management questions. We evaluate each research program's relative emphasis on three principal elements of biodiversity organization: composition, structure, and function. This approach is used to analyze existing ecosystem-wide biodiversity knowledge and to assess what is known and where gaps exist. In all four of these systems and studies, there is a relative paucity of investigation on functional elements of biodiversity, when compared with compositional and structural elements. This is symptomatic of the current state of the science. Substantial investment in understanding one or more biodiversity element(s) will allow issues to be addressed in a timely and more integrative fashion. Evaluating research needs and possible approaches across specific elements of biodiversity organization can facilitate planning of future studies and lead to more effective communication between scientists, managers, and stakeholders. Building a general approach that captures how various studies have focused on different biodiversity elements can also contribute to meta-analyses of worldwide experience in scientific research to support ecosystem-based management

Phytoplankton Dynamics within a Discrete Water Mass off Cape Hatteras, North Carolina: the Lagrangian Experiment

As part of the Department of Energy Ocean Margins Program, we examined the spatial and temporal variability in primary production and phytoplankton pigments during two cruises to the shelf waters between the Chesapeake Bay and Cape Hatteras. The first cruise was conducted in March 1996, reflecting well-mixed conditions just prior to the spring transition, while the second cruise was conducted during July 1996 when the water column was more stratified. During each cruise, primary production and high performance liquid chromatography (HPLC) pigments for the whole community and \u3c8-mum size fraction were determined for several successive days within a discrete water mass by following a near-surface tracking drogue. In March, production ranged from 0.50 to 0.65 g C m(-2) d(-1), with 52-62% of the production attributed to the smaller size fraction. About 50% of the total chlorophyll a (chl a) was found in the \u3e 8-mum size fraction. Pigment composition was dominated by chlorophylls a, c(1) and c(2), and fucoxanthin, indicating the importance of diatoms. In July, production was more variable, ranging from 0.38 to 2.09 g C m(-2) d(-1), with 41-83% of production attributed to the \u3c8-mum size fraction. Rates increased over the 4-day study. Most of the chi a was found in the \u3c8-mum size fraction. The phytoplankton pigments were dominated by chi a and fucoxanthin with chlorophylls c(1) and c(2), again indicating the importance of diatoms during this cruise.CHEMTAX (Mackey et al. CHEMTAX User\u27s Manual: a program for estimating class abundances from chemical markers-application to HPLC measurements of phytoplankton pigments. CSIRO Marine Laboratories, Report 229, Hobart, 42 pp.), a factor analysis computer program, was used to examine phytoplankton community structure using marker pigments from our HPLC analyses to determine the relative importance of various taxa. In March, diatoms dominated whole water samples, with consistent contributions from dinoflagellates and cryptophytes. The \u3c8-mum fraction was dominated by small diatoms, chrysophytes, cryptophytes and dinoflagellates. In July, diatoms were still present and important, but prymnesiophytes, cryptophytes and cyanobacteria contributed in both size classes. Correlation analyses indicated that primary production was positively correlated with light and temperature. Chl a biomass was positively correlated with the concentrations of NO2 + NO3 and negatively correlated with temperature. These correlations support the observation that temperature played a major role in the phytoplankton dynamics in this shelf ecosystem. (C) 2002 Elsevier Science Ltd. All rights reserved

A comparative overview of weathering intensity and HCO3- flux in the world's major rivers with emphasis on the Changjiang, Huanghe, Zhujiang (Pearl) and Mississippi Rivers

In this paper, general relationships of riverine bicarbonate concentrations and fluxes as a function of drainage basin mineral content and runoff are examined using a database of the 25 largest rivers in the world. Specific HCO3- flux normalized to unit basin area, which peaks in the mid latitudes, was found to be strongly correlated with the carbonate mineral content of river basins, while river HCO3- concentration was related to the balance of precipitation and evaporation. Within this global context, the weathering patterns of CO2 in a few large rivers (Changjiang, Huanghe, Pearl, and Mississippi rivers) were examined in further detail. The Zhujiang (Pearl River), especially its largest branch (Xijiang), was characterized by the highest specific weathering rate among all the world's large rivers due to an exceptionally high carbonate mineral content (over 80\%) in its drainage basin and its warm and wet environment. It has a moderate level of HCO3- concentration, however, due to dilution by relatively high precipitation in the watershed. In stark contrast, the Huanghe (Yellow River) has one of the lowest specific weathering rates because of low carbonate mineral content and a dry climate. However, it has a high HCO3- concentration due largely to the concentrating effects of high evaporative water loss, as a result of and weather and the agricultural use of water through irrigation systems, as well as carbonate-containing surficial deposits (i.e., loess). The strong correlation between specific HCO3- fluxes and discharge in all four rivers with different discharge seasonality suggests that higher precipitation in drainage basins promotes higher weathering rates. For the 25 large rivers studied here, rivers in low (< 30 degrees), mid (30-60 degrees) and high (> 60 degrees) latitudes have an average HCO3- concentration of 0.584, 1.649, and 1.154mM, respectively, and they account for 42.6\%, 47.3\% and 10.1\%, respectively, of the total global dissolved inorganic carbon flux to the ocean. Thus the mid-latitude rivers carry a disproportionally high dissolved inorganic carbon flux with a relatively small (26\%) amount of freshwater discharge. The discharge-averaged global river HCO3- concentration was estimated to be 1.1 mM. (c) 2008 Elsevier Ltd. All rights reserved

The specific inherent optical properties of three sub-tropical and tropical water reservoirs in Queensland, Australia

The underwater light climate, which is a major influence on the ecology of aquatic systems, is affected by the absorption and scattering processes that take place within the water column. Knowledge of the Specific Inherent Optical Properties (SIOPs) of water quality parameters and their spatial variation is essential for the modelling of underwater light fields and remote sensing applications. We measured the SIOPs and water quality parameter concentrations of three large inland water impoundments in Queensland, Australia. The measurements ranged from 0.9–42.7 μgl/1 for chlorophyll a concentration, 0.9–170.4 mgl/1 for tripton concentration, 0.36–1.59 m/1 for aCDOM(440) and 0.15–2.5 m for Secchi depth. The SIOP measurements showed that there is sufficient intra-impoundment variation in the specific absorption and specific scattering of phytoplankton and tripton to require a well distributed network of measurement stations to fully characterise the SIOPs of the optical water quality parameters. While significantly different SIOP sets were measured for each of the study sites the measurements were consistent with published values in other inland waters. The multiple measurement stations were allocated into optical domains as a necessary step to parameterise a semi-analytical inversion remote sensing algorithm. This paper also addresses the paucity of published global inland water SIOP sets by contributing Australian SIOP sets to allow international and national comparison

Acidification of subsurface coastal waters enhanced by eutrophication

US EPA; NSF; NASA; National Natural Science Foundation of China; National Basic Research Program of China; National Science Council of the Republic of ChinaHuman inputs of nutrients to coastal waters can lead to the excessive production of algae, a process known as eutrophication. Microbial consumption of this organic matter lowers oxygen levels in the water(1-3). In addition, the carbon dioxide produced during microbial respiration increases acidity. The dissolution of atmospheric carbon dioxide in ocean waters also raises acidity, a process known as ocean acidification. Here, we assess the combined impact of eutrophication and ocean acidification on acidity in the coastal ocean, using data collected in the northern Gulf of Mexico and the East China Sea-two regions heavily influenced by nutrient-laden rivers. We show that eutrophication in these waters is associated with the development of hypoxia and the acidification of subsurface waters, as expected. Model simulations, using data collected from the northern Gulf of Mexico, however, suggest that the drop in pH since pre-industrial times is greater than that expected from eutrophication and ocean acidification alone. We attribute the additional drop in pH-of 0.05 units-to a reduction in the ability of these carbon dioxide-rich waters to buffer changes in pH. We suggest that eutrophication could increase the susceptibility of coastal waters to ocean acidification

Contribution of hurricanes to local and global estimates of air–sea exchange of CO2

The effect of hurricanes on the thermal and physical structure of the upper ocean has been described1 but their influence on the ocean carbon cycle and the exchange of carbon between ocean and atmosphere is not well understood. Here we present observations from the Sargasso Sea, before and after hurricane Felix in summer 1995, that show a short-lived (2–3 weeks) surface seawater cooling of about 4 °C, and a decrease in seawater partial pressure of CO2 by about 60 microatm. Despite the localized decrease in seawater partial pressure of CO2, strong winds during the passage of hurricane Felix increased the efflux of CO2 from ocean to atmosphere. We estimate that hurricane Felix and two other hurricanes increased the summertime efflux of CO2 into the atmosphere over this part of the Sargasso Sea by nearly 55%. We estimate that hurricanes contribute to the global ocean-to-atmosphere flux of CO2 by between +0.04 to +0.51 Pg C (1015 g C) per year. Such hurricane-forced effluxes are quantitatively significant compared to regional (14° to 50° N zone)2 and global effluxes2,3. Hurricanes therefore exert an important influence on ocean–atmosphere CO2 exchange and the inferred4 year-to-year variability of CO2 fluxes over the subtropical oceans