Eutrophication,water management,and the functioning of Dutch estuaries and coastal lagoons

A number of major European rivers (especially the Rhine) have a prevailing influence on the nutrient cycling of most Dutch estuaries. Owing to the increased loading of the estuaries with nitrogen and phosphorus compounds, effects of eutrophication on the biological communities are most evident in the tidal Western Wadden Sea and in a nontidal brackish lagoon, Veerse Meer. Whether the relation between changed nutrient loadings and changed biomass and production of primary and secondary producers in the turbid tidal Dutch ecosystems should be considered as a causal relation is questionable. The very widespread practice of lagoon modification confuses the effects of nutrient loading.     

Control of nutrient concentrations in the Seekonk-Providence River region of Narragansett Bay,Rhode Island

Six synoptic samplings of nutrient concentrations of the water column and point-source inputs (rivers, sewage treatment plants) were conducted in the Seekonk-Providence River region of Narragansett Bay. Concentrations of nutrients (NH₄ ⁺, NO₂ ^?+NO₃ ^?, PO₄ ^?3, dissolved silicon, particulate N, particulate C) were predicted using a conservative, two-layer box model in order to assess the relative influence of external inputs and internal processes on observed concentrations. Although most nutrients were clearly affected by processes internal to the system, external input and mixing explained most of the variability in and absolute magnitude of observed concentrations, especially for dissolved constituents. In the bay as a whole, two functionally distinct regions can now be identified: the Seekonk-Providence River, where dissolved nutrient concentrations are externally controlled and lower Narragansett Bay where internal processes regulate the behavior of nutrients. A preliminary nitrogen budget suggests that the Seekonk-Providence River exports some 95% of the nitrogen entering the system via point sources and bottom water from upper Narragansett Bay.     

The history of Cu,Pb, and Zn inputs to Narragansett Bay,Rhode Island as recorded by salt-marsh sediments

The distribution of metals with depth in sediment cores sampled from industrialized estuaries can reveal long-term trends in loadings to the waterbody. Salt marsh cores were sampled from five locations from the head to the mouth of Narragansett Bay and from one location from a marsh inside a lagoon on the coast of Block Island Sound with the intent of reconstructing historical loadings of Pb, Cu, and Zn to this estuary. Concentrations of Fe and Mn were measured as indicators of redox conditions of the sediment column. Chronologies were developed using accretion rates determined previsly from²¹⁰Pb analyses of the same cores. Excess metal inventories and enrichment over pre-industrial concentrations were greater in upper bay cores reflecting the location of sources at the head of the estuary. The bay cores were similar with respect to the distributions of Cu, Pb, and Zn. Concentrations of all metals began to increase over background levels at depths corredponding approximately to the year 1900. Most of the cores showed peak concentrations of Cu and Pb in the early 1950s and 1970s. Distributions of Zn were more variable among cores, showing peaks in the early 1920s in some cores and in the 1950s and 1970s in others. In general, the observed distributions in the bay cores are consistent with estimated long-term trends in loadings from atmospheric and sewage sources. The metal distributions in the lagoon core appear to reflect atmospheric loadings. However, there are features in some cores that are not explainable using the estimated trends in source inputs. There also is not a 1∶1 correspondence between changes in sediment metal concentrations and changes in loadings. It is likely that this method of reconstruction would benefit from a more detailed characterization of sources, but comparison of sediment and historical records do show that attempts to reduce loadings to the bay have been successful.     

Sources of nutrient inputs to the Patuxent River estuary

We quantified annual nutrient inputs to the Patuxent River estuary from point and nonpoint sources and from direct atmospheric deposition. We also compared nonpoint source (NPS) discharges from Piedmont and Coastal Plain regions and from agricultural and developed lands. Using continuous automated-sampling, we measured discharges of water, nitrogen, phosphorus, organic carbon (C), and suspended solids from a total of 23 watersheds selected to represent various proportions of developed land and cropland in the Patuxent River basin and the neighboring Rhode River basin. The sampling period spanned two years that differed in annual precipitation by a factor of 1.7. Water discharge from the watershed to the Patuxent River estuary was 3.4 times higher in the wet year than in the dry year. Annual water discharges from the study watersheds increased as the proportion of developed land increased. As the proportion of cropland increased, there were increases in the annual flow-weighted mean concentrations of nitrate (NO₃ ^?), total nitrogen (TN), dissolved silicate (Si), total phosphate (TPO₄ ^3?), total organic phosphorus (TOP), total P (TP), and total suspended solids (TSS) in NPS discharges. The effect of cropland on the concentrations of NO₃ ^? and TN was stronger for Piedmont watersheds than for Coastal Plain watersheds. As the proportion of developed land increased, there were increases in annual mean concentrations of NO₃ ^?, total ammonium (TNH₄ ⁺), total organic N (TON), TN, total organic C (TOC), TPO₄ ^3?, TOP, TP, and TSS and decreases in concentrations of Si. Annual mean concentrations of TON, TOC, forms of P, and TSS were highest in the wet year. Annual mean concentrations of NO₃ ^?, TNH₄ ⁺, TN, and Si did not differ significantly between years. We directly measured NPS discharges from about half of the Patuxent River basin and estimated discharges from the other half of the basin using statistical models that related annual water flow and material concentrations to land cover and physiographic province. We compared NPS discharges to public data on point source (PS) discharges. We estimated direct atmospheric deposition of forms of N, P, and organic C to the Patuxent River estuary based on analysis of bulk deposition near the Rhode River. During the wet year, most of the total terrestrial and atmospheric inputs of forms of N and P came from NPS discharges. During the dry year, 53% of the TNH₄ ⁺ input was from atmospheric deposition and 58% of the NO₃ ^? input was from PS discharges; NPS and PS discharges were about equally important in the total inputs of TN and TPO₄ ^3?. During the entire 2-yr period, the Coastal Plain portion of the Patuxent basin delivered about 80% of the NPS water discharges to the estuary and delivered similar proportions of the NPS TNH₄ ⁺, TN, TOP, and TSS. The Coastal Plain delivered greater proportions of the NPS TON, TOC, Si, and TP (89%, 90%, 93%, and 95%, respectively) than of water, and supplied nearly all of the NPS TPO₄ ^3? (99%). The Piedmont delivered 33% of the NPS NO₃ ^? while delivering only 20% of the NPS water to the stuary. We used statistical models to infer the percentages of NPS discharges supplied by croplands, developed lands, and other lands. Although cropland covers only 10% of the Patuxent River basin, it was the most important source of most materials in NPS discharge, supplying about 84% of the total NPS discharge of NO₃ ^?; about three quarters of the TPO₄ ^3?, TOP, TP, and TSS; and about half of the TNH₄ ⁺ and TN. Compared to developed land, cropland supplied a significantly higher percentage of the NPS discharges of NO₃ ^?, TN, TPO₄ ^3?, TOP, TP, and TSS, despite the fact development land covered 12% of the basin.     

Rank of coal beds of the Narragansett basin,Massachusetts and Rhode Island

Coal of the Narragansett basin generally has been considered to be anthracite and/or meta-anthracite. However, no single reliable method has been used to distinguish these two ranks in this basin. Three methods — chemical, X-ray, and petrographic — have been used with some degree of success on coal of the Narragansett basin, but too often the results are in conflict. Chemical methods have been limited by inadequate sampling on a coal-bed-by-coal-bed basis and by a lack of analyses made according to (American Society for Testing and Materials, 1974) standard specifications.In addition, when corrections are made by using the Parr formulas, as required by the ASTM (1974) procedures, the generally high to very high ash content of coal from the Narragansett basin causes the fixed-carbon content to appear higher than it actually is. X-ray methods using the degree of graphitization as a measure of rank are not reliable because some of the graphite is related to shearing and brecciation associated with folding and faulting. Petrographic methods using reflectance on vitrinite give results that are generally consistent with results from chemical determinations. However, it is not clear whether the mean maximum reflectance or mean bireflectance is a better indicator of similar rank of such high-rank coals that have been structurally deformed.Coal from the Cranston Mine, RI, is probably meta-anthracite and coal from the Portsmouth Mine is probably anthracite. These ranks are based on chemical,X-ray, and petrographic data and are supported by associated metamorphic mineral assemblages that indicate that the Cranston Mine is in a higher metamorphic zone than the zone containing the Porthmouth Mine. Interpretation of the rank of Mansfield, MA, coal on the basis of extant chemical data is difficult because it is an impure coal with an ash content of 33 to 50%. Reflectance data indicate that the Mansfield, Foxborough, and Plainville coals in the northern part of the Narragansett basin are meta-anthracite but this is in disagreement with the rank suggested by the low degree of metamorphism of the associated rocks.     

Local, state, regional, and federal roles in coastal nutrient management

A number of local, regional, state, and federal programs are in place that strive to protect and restore coastal waters and habitats, and which specifically address eutrophication and nutrient over-enrichment. There are, however, no easily implemented and reliable methods or sources of data and information for citizens, coastal managers, elected officials, and agency staff who are responsible for managing a coastal area to determine sources of nutrients and potential impacts to coastal waters. Coordination among federal and local agencies remains inadequate. In the few examples of successful coastal nutrient management programs, effective nutrient management strategies are often partnerships of national, regional, and local efforts. The recent National Research Council (2000) examination of issues and management options calls for development of a National Coastal Nutrient Management Strategy, coordinated between national, state and local programs, academia, and the private sector. The proposed National Coastal Nutrient Management Strategy includes recommendations for local programs to consider in developing an effective nutrient management strategy, such as setting goals for restoration, determining nutrient reductions needed to meet goals, and monitoring results. The proposed strategy also identifies priority actions which federal programs should consider, including identifying gaps and overlaps in existing and proposed national programs for all aspects of nutrient over-enrichment; increasing accessibility to data, information and expertise on nutrient over-enrichment causes, effects, and management options; and setting clear guidelines for nutrient loads. A nationally consistent monitoring program and targeted research, specifically for atmospheric deposition, seasonal variability of nitrogen and phosphorus enrichment effects, the role of specific nutrients in the occurrence of harmful algal blooms, and economic impacts of nutrient over-enrichment were also identified as priority needs.     

水体富营养化与水体沉积物释放营养盐

水体富营养化已经成为世界水环境面临的最为重要的问题.简要介绍了中国水体富营养化的现状和水体富营养化的成因.着重阐述了在截断外源污染后,水体沉积物对营养盐的释放及其主要影响因素,并提出了目前存在的问题和未来的发展方向,为水体富营养化的研究、预防和治理工作提供了系统、科学的理论依据.     

Nutrient inputs to the Choptank River estuary: Implications for watershed management

Degraded water quality due to water column availability of nitrogen and phosphorus to algal species has been identified as the primary cause of the decline of submersed aquatic vegetation in Chesapeake Bay and its subestuaries. Determining the relative impacts of various nutrient delivery pathways on estuarine water quality is critical for developing effective strategies for reducing anthropogenic nutrient inputs to estuarine waters. This study investigated temporal and spatial patterns of nutrient inputs along an 80-km transect in the Choptank River, a coastal plain tributary and subestuary of Chesapeake Bay, from 1986 through 1991. The study period encompassed a wide range in freshwater discharge conditions that resulted in major changes in estuarine water quality. Watershed nitrogen loads to the Choptank River estuary are dominated by diffuse-source inputs, and are highly correlated to freshwater discharge volume. in years of below-average freshwater discharge, reduced nitrogen availability results in improved water quality throughout most of the Choptank River. Diffuse-source inputs are highly enriched in nitrogen relative to phosphorus, but point-source inputs of phosphorus from sewage treatment plants in the upper estuary reduce this imbalance, particularly during summer periods of low freshwater discharge. Diffuse-source nitrogen inputs result primarily from the discharge of groundwater contaminated by nitrate. Contamination is attributable to agricultural practices in the drainage basin where agricultural land use predominates. Groundwater discharge provides base flow to perennial streams in the upper regions of the watershed and seeps directly into tidal waters. Diffuse-source phosphorus inputs are highly episodic, occurring primarily via overland flow during storm events. Major reductions in diffuse-source nitrogen inputs under current landuse conditions will require modification of agricultural practices in the drainage basin to reduce entry rates of nitrate into shallow groundwater. Rates of subsurface nitrate delivery to tidal waters are generally lower from poorly-drained versus well-drained regions of the watershed, suggesting greater potential reductions of diffuse-source nitrogen loads per unit effort in the well-drained region of the watershed. Reductions in diffuse-source phosphorus loads will require long-term management of phosphorus levels in upper soil horizons. *** DIRECT SUPPORT *** A01BY074 00021     

Sources of nutrient pollution to coastal waters in the United States: Implications for achieving coastal water quality goals

Some 60% of coastal rivers and bays in the U.S. have been moderately to severely degraded by nutrient pollution. Both nitrogen (N) and phosphorus (P) contribute to the problem, although for most coastal systems N additions cause more damage. Globally, human activity has increased the flux of N and P from land to the oceans by 2-fold and 3-fold, respectively. For N, much of this increase has occurred over the past 40 years, with the increase varying by region. Human activity has increased the flux of N in the Mississippi River basin by 4-fold, in the rivers of the northeastern U.S. by 8-fold, and in the rivers draining to the North Sea by more than 10-fold. The sources of nutrients to the coast vary. For some estuaries, sewage treatment plants are the largest single input; for most systems nonpoint sources of nutrients are now of relatively greater importance, both because of improved point source treatment and control (particularly for P) and because of increases in the total magnitude of nonpoint sources (particularly for N) over the past three decades. For P, agricultural activities dominate nonpoint source fluxes. Agriculture is also the major source of N in many systems, including the flux of N down the Mississippi River, which has contributed to the large hypoxic zone in the Gulf of Mexico. For both P and N, agriculture contributes to nonpoint source pollution both through losses at the field scale, as soils erode away and fertilizer is leached to surface and ground waters, and from losses from animal feedlot operations. In the U.S. N from animal wastes that leaks directly to surface waters or is volatilized to the atmosphere as ammonia may be the single largest source of N that moves from agricultural operations into coastal waters. In some regions, including the northeastern U.S., atmospheric deposition of oxidized N from fossil-fuel combustion is the major flux from nonpoint sources. This atmospheric component of the N flux into estuaries has often been underestimated, particularly with respect to deposition onto the terrestrial landscape with subsequent export downstream. Because the relative importance of these nutrient sources varies among regions and sites, so too must appropriate and effective mitigation strategies. The regional nature and variability of nutrient sources require that nutrient management efforts address large geographic areas.     

Nutrient inputs from the watershed and coastal eutrophication in the Florida keys

Widespread use of septic tanks in the Florida Keys increase the nutrient concentrations of limestone groundwaters that discharge into shallow nearshore waters, resulting in coastal eutrophication. This study characterizes watershed nutrient inputs, transformations, and effects along a land-sea gradient stratified into four ecosystems that occur with increasing distance from land: manmade canal systems (receiving waters of nutrient inputs), seagrass meadows, patch reefs, and offshore bank reefs. Soluble reactive phosphorus (SRP), the primary limiting nutrient, was significantly elevated in canal systems compared to the other ecosystems, while dissolved inorganic nitrogen (DIN; NH₄ ⁺ and NO₃ ^?) a secondary limiting nutrient, was elevated both in canal systems and seagrass meadows. SRP and NH₄ ⁺ concentrations decreased to low concentrations within approximately 1 km and 3 km from land, respectively. DIN and SRP accounted for their greatest contribution (up to 30%) of total N and P pools in canals, compared to dissolved organic nitrogen (DON) and dissolved organic phosphorus (DOP) that dominated (up to 68%) the total N and P pools at the offshore bank reefs. Particulate N and P fractions were also elevated (up to 48%) in canals and nearshore seagrass meadows, indicating rapid biological uptake of DIN and SRP into organic particles. Chlorophylla and turbidity were also elevated in canal systems and seagrass meadows; chlorophylla was maximal during summer when maximum watershed nutrient input occurs, whereas turbidity was maximal during winter due to seasonally maximum wind conditions and sediment resuspension. DO was negatively correlated with NH₄ ⁺ and SRP; hypoxia (DO<2.5 mg l^?1) frequently occurred in nutrient-enriched canal systems and seagrass meadows, especially during the warm summer months. These findings correlate with recent (<5 years) observations of increasing algal blooms, seagrass epiphytization and die-off, and loss of coral cover on patch and bank reef ecosystems, suggesting that nearshore waters of the Florida Keys have entered a stage of critical eutrophication.     

Quantifying Contributions to Light Attenuation in Estuaries and Coastal Embayments: Application to Narragansett Bay,Rhode Island

In Narragansett Bay, light attenuation by total suspended sediments (TSS), colored dissolved organic matter (CDOM), and phytoplankton chlorophyll-a (chl-a) pigment is 129, 97, and 70%, respectively, of that by pure seawater. Spatial distribution of light attenuation indicates higher values in the upper Bay, where rivers with sediment and nutrient-rich waters enter and elevate TSS, CDOM, and chl-a concentrations. The temporal trends of light attenuation during the summer months (July–August) differed at various locations in the Bay, having the highest values in July. For the same period, spectral methods overestimated attenuation throughout the Bay. These findings quantify the behavior of light attenuation in space and time, providing information that can guide decisions related to improving water clarity and help understanding the effects of various environmental and management scenarios on it.     

Hypoxic events in Narragansett Bay, Rhode Island, during the summer of 2001

Bottom water hypoxic events were observed in Narragansett Bay, Rhode Island during the summer of 2001 using a towed sensor, vertical casts at fixed stations, and continuous monitoring buoys. This combination of approaches allowed for both extensive spatial and temporal sampling. Oxygen concentrations below the U.S. Environmental Protection Agency (EPA) acute hypoxia criterion of 2.3 mg l^?1 were observed in the northern parts of Narragansett Bay, including the Providence River. We estimate 39% of the area of the Providence River was affected by acute hypoxia between July and September 2001. All other regions experienced only small areas of acute hypoxia (<5%), and no acute hypoxia was observed from Quonset Point south. The area encompassing oxygen concentrations below the EPA chronic hypoxia criterion of 4.8 mg l^?1 was much more extensive in the upper half of Narragansett Bay, sometimes covering the majority of the region, though it is unclear whether exposure to concentrations below this criterion persisted long enough to significantly affect marine species in these areas. Vertical profiles of dissolved oxygen typically exhibited a mid water oxygen minimum near the pycnocline, followed by a slight increase in oxygen with depth. The surface waters above the pycnocline were typically supersaturated with oxygen. The northern portions of the Bay where the most extensive hypoxia was observed corresponded to the regions with both the greatest thermohaline stratification, the highest nutrient inputs, and the highest primary productivity.     

Challenges and opportunities for science in reducing nutrient over-enrichment of coastal ecosystems

Nutrient over-enrichment has resulted in major changes in the coastal ecosystems of developed nations in Europe, North America, Asia, and Oceania, mostly taking place over the narrow period of 1960 to 1980. Many estuaries and embayments are affected, but the effects of this eutrophication have been also felt over large areas of semi-enclosed seas including the Baltic, North, Adriatic, and Black Seas in Europe, the Gulf of Mexico, and the Seto Inland Sea in Japan. Primary production increased, water clarity decreased, food chains were altered, oxygen depletion of bottom waters developed or expanded, seagrass beds were lost, and harmful algal blooms occurred with increased frequency. This period of dramatic alteration of coastal ecosystems, mostly for the worse from a human perspective, coincided with the more than doubling of additions of fixed nitrogen to the biosphere from human activities, driven particularly by a more than 5-fold increase in use of manufactured fertilizers during that 20-year period. Nutrient over-enrichment often interacted synergistically with other human activities, such as overfishing, habitat destruction, and other forms of chemical pollution, in contributing to the widespread degradation of coastal ecosystems that was observed during the last half of the 20th century. Science was effective in documenting the consequences and root causes of nutrient over-enrichment and has provided the basis for extensive efforts to abate it, ranging from national statutes and regulations to multijurisdictional compacts under the Helsinki Commission for the Baltic Sea, the Oslo-Paris Commission for the North Sea, and the Chesapeake Bay Program, for example. These efforts have usually been based on a relatively arbitrary goal of reducing nutrient inputs by a certain percentage, without much understanding of how and when this would affect the coastal ecosystem. While some of these efforts have succeeded in achieving reductions of inputs of phosphorus and nitrogen, principally through treatment of point-source discharges, relatively little progress has been made in reducing diffuse sources of nitrogen. Second-generation management goals tend to be based on desired outcomes for the coastal ecosystem and determination of the load reductions needed to attain them, for example the Total Daily Maximum Load approach in the U.S. and the Water Franmework Directive in the European Union. Science and technology are now challenged not just to diagnose the degree of eutrophication and its causes, but to contribute to its prognosis and treatment by determining the relative susceptibility of coastal ecosystems to nutrient over-enrichment, defining desirable and achievable outcomes for rehabilitation efforts, reducing nutrient sources, enhancing nutrient sinks, strategically targeting these efforts within watersheds, and predicting and observing responses in an adaptive management framework.     

加强管理保护沿海地质环境

江苏沿海大陆岸线长９５３．９ｋｍ,海岸带面积约３．５万ｋｍ＾３,滩涂面积５０００ｋｍ＾２,而且每年向外海新增土地两万多亩,还拥有举世瞩目的辐射状海底沙脊群,海平面以上部分就有４００ｋｍ＾２,是江苏省宝贵的后备国土资源。沿海地区是江苏新的经济增长点。改革开放以来,沿海地区经济的发展,加之地表水体的污染逐年严重,对优质地下淡水的开采逐年增加,原有的地质环境受到破坏,出现了地下水位下降,地下淡水资源减少     

Sediment grain size and hydrodynamics in Mediterranean coastal lagoons: Integrated classification of abiotic parameters

Integrated classification maps were produced by combining sediment grain-size and hydrological data (water renewal time, WRT) from two Mediterranean lagoons, Lesina (LL) and Varano (LV), Italy. The geophysical characteristics of the two basins, derived from detailed bathymetric charts, are quite distinct: ～30% of LL (mean depth ～1 m) but only 3% of LV (mean depth ～3 m) is shallower than 1 m. The sediments of both lagoons are mainly composed of mud (～80%). A detailed multivariate analysis of grain-size data by EntropyMax classified the lagoon beds of LL and LV into five sedimentary facies. WRT data, computed by a hydrodynamic model, indicated different hydrological conditions in the two lagoons: LL showed a sharp west–east gradient, with a basin-wide average of ～190 days, whilst LV showed a fairly uniform distribution and a higher basin-wide average (～260 days). The distribution of sedimentary facies and water renewal times were combined in a composite map representing the distribution of environmental patterns. The approach outlined in this study can be used to improve zonation schemes by providing a hydromorphological perspective on transitional and coastal environments.     

Submarine Groundwater Discharge as a Source of Dissolved Inorganic Nitrogen and Phosphorus to Coastal Ponds of Southern Rhode Island

Measurements of groundwater-dissolved inorganic nitrogen (nitrate?+?nitrite?+?ammonia) and phosphate concentrations were combined with recent, radium-based, submarine groundwater discharge (SGD) fluxes and prior estimates of SGD determined from Darcy’s Law, a hydrologic model, and total recharge to yield corresponding SGD nutrient fluxes to Ninigret, Point Judith, Quonochontaug, and Winnapaug ponds, located in southern Rhode Island. Results range from 80 to279 mmol N m^?2 year^?1 and 4 to 15 mmol P m^?2 year^?1 for Ninigret, 48 to 265 mmol N m^?2 year^?1 and 4 to 23 mmol P m^?2 year^?1 for Point Judith, 31 to 62 mmol N m^?2 year^?1 and 1 to 2 mmol P m^?2 y^?1 for Quonochontaug, and 668 to 1,586 mmol N m^?2 year^?1 and 29 to 70 mmol P m^?2 year^?1 for Winnapaug ponds, respectively. On a daily basis, the SGD supply of dissolved inorganic nitrogen and phosphorus is estimated to represent ～1–6 % of the total amount of these nutrients in surface waters of Ninigret, Point Judith, and Quonochontaug ponds and up to 84 and 17 % for Winnapaug, respectively, which may reflect a greater SGD nutrient supply to this pond because of the proximity of fertilized golf courses. With regard to the total external input of these essential nutrients, SGD represents 29–45 % of dissolved inorganic nitrogen input to Ninigret, Point Judith, and Quonochontaug ponds and as much as 93 % for Winnapaug pond. For phosphorus, the contribution from SGD represents 59–85 % of the total external input for Ninigret, Point Judith, and Quonochontaug ponds and essentially all of the phosphorus input to Winnapaug pond. Estimated rates of primary productivity potentially supported by the average supply of dissolved inorganic nitrogen from SGD range from 10 g C m^?2 year^?1 for Ninigret, 13 g C m^?2 year^?1 for Point Judith, 4 g C m^?2 year^?1 for Quonochontaug, and as high as 84 g C m^?2 y^?1 for Winnapaug pond. The imputed SGD-derived rates of primary productivity represent 4–9 % of water column primary production for Ninigret, Point Judith, and Quonochontaug ponds, and 74 % for Winnapaug pond, a result that is reasonably comparable to several other coastal environments where estimates of SGD nutrient supply have been reported. The implication is that SGD represents an ecologically significant source of dissolved nutrients to the coastal salt ponds of southern Rhode Island and, by inference, other coastal systems.     

Some life history aspects of the seaboard goby (gobiosoma ginsburgi) in Rhode Island

This paper represents the first report of adultG. ginsburgi from Rhode Island waters since 1938. Gobies were collected only from subtidal shell communities in high salinity waters. Seaboard gobies eat a variety of benthic invertebrates but feed most heavily on harpacticoid copepods. Gravid females collected in July contained one size class of ova indicating a single spawning per season. Egg counts ranged from 1268 to 1977 per female. Larval densities indicate that peak spawning occurs in July and suggest thatG. ginsburgi is more abundant in the Sakonnet River and nearby Narragansett Bay than previously reported.     

Natural to anthropogenic forcing in the Holocene evolution of three coastal lagoons (Caldas da Rainha valley, western Portugal)

In the coast of Central Portugal three lagoons were created by the Holocene flooding of diapiric-related depressions but experienced afterwards a significant sediment accumulation. Fast environmental and morphological changes after the Middle Holocene were clearly forced by anthropogenic activities since the Middle Ages and show a strong feedback on the human communities. Erosion in the studied watersheds depends on climatic and anthropic changes; especially, demographic rises increase agriculture and deforestation in the watersheds, and sedimentation in the lagoons. The region was successively occupied by ethnic groups since the Neolithic (including Romans, Sueves, Visigoths and Muslims), but the main changes were largely due to anthropic forcing following the Christian Reconquest by the Kingdom of Portugal. In fact, during the Middle Ages and Renaissance the area had intense nautical, fishing and agricultural activities, even if reduced during the 14th century crisis. Later, due to severe sediment accumulation and shoaling, sailing was drastically reduced and most of the area drowned in the maximum transgression was claimed to farming. It is also noteworthy that the social evolution and sediment entrainment in the watersheds appear to be in tune with climatic trends deduced after regional and global data. In synthesis, we conclude that the human activities during the last millennium greatly accelerated the natural silting trend of the lagoons.     

Standing stock and estimated production rates of phytoplankton and zooplankton in Narragansett Bay,Rhode Island

Seasonal changes in phytoplankton biomass and production, total zooplankton biomass, and biomass and potential production rates of the two dominant copepods, Acartia hudsonica (formerly called Acartia clausi) and Acartia tonsa are described for several stations in Narragansett Bay, R.I. Plankton in the bay behaved as a single population with simultaneous changes occurring at the upper bay (Station 5) and the lower bay (Station 1). Phytoplankton biomass was higher in the upper bay ( \(\bar x\) =16.95 mg chl a·m^?3) than in the lower bay ( \(\bar x\) =6.37 mg chl a·m^?3) and these 0269 0101 V differences in biomass were reflected in the phytoplankton production rates. The zooplankton, which was dominated by A. hudsonica in the spring and early summer and A. tonsa during summer and fall, showed no such consistent differences between the stations. Mean A. hudsonica biomass (St 1, \(\bar x\) ;=82.7 mg dry wt·m^?3; St 5, _ \(\bar x\) ;=95.2 mg dry wt·m^?3) exceeded that of A. tonsa (St 1, \(\bar x\) ;=56.7 mg dry wt·m^?3; St 5, \(\bar x\) ;=60.0 mg dry wt·m^?3). Potential production rates of the two Acartia 0269 0101 V spp. were strongly temperature dependent. Despite the higher biomass levels of A. hudsonica, low temperatures resulted in lower potential production rates ( \(\bar x\) ; St 1=7.25 mg C·m^?3 day^?1; \(\bar x\) ; St 5=10.77mg C·m^?3 day^?1) and biomass doubling times of up to 9.6 days. Potential production rates of A. tonsa at summer temperatures were high ( \(\bar x\) ; St 1=19.0 mg C·m^?3 day^?1; \(\bar x\) ; St 5=22.9 mg C·m^?3 day^?1) and biomass doubling times were generally less than one day.