Great Bay Estuary System Research Articles

Long-Term Simulations of Wastewater Treatment Facility Discharges into the Great Bay Estuarine System (New Hampshire)

The establishment of numeric nutrient criteria for the Great Bay Estuary System (GBES) to improve water quality used a computer modeling approach to determine how much of the waste water treatment facility (WWTF) discharges were responsible for nitrogen entering GBES. The Great Bay Estuary, located in southeastern New Hampshire, is a relatively shallow (a tidal amplitude to mean depth ratio of 0.18), well-mixed tidal estuary with a wet area of \(24\,\mathrm{km}^{2}\) and a main channel length of approximately 26 km. The dominant tide is the principal lunar (M2). The modeling approach includes both a finite element, two-dimensional, vertically averaged, time stepping circulation model, and a Lagrangian particle tracking module. The spatial discretization uses finite element triangles with a characteristic length (\(\surd 2A\) where A is the triangle area) of roughly 3 m in the estuary. The time discretization uses a time step of 99.36 s. The particle model does not include vertical motion, and the particles are neutrally buoyant passive particles. Several WWTF discharges were selected and run separately as a continuous release of conservative particles. The percentages of particles residing in each region at the end of the simulation time (65 days) from each source were summarized to allow comparison. In addition, the percentage of particles scaled by the total nitrogen load from all WWTFs was also summarized for each region. It was thus possible to assess the relative contribution of each of the selected WWTF modeled made to each region.

A Floristic Comparison of Benthic “Marine” Algae In Bras D'Or Lake, Nova Scotia With Five Other Northwest Atlantic Embayments and the Baltic Sea In Northern Europe

The seaweed flora of Bras d'Or Lake, Cape Breton Island, Nova Scotia is compared with those of the Baltic Sea in northern Europe and five Northwest Atlantic embayments ranging from Pomquet Harbour, Nova Scotia to Narragansett Bay, Rhode Island. Both Bras d'Or Lake and the Baltic Sea have experienced extensive geological and hydrographic changes during the past 15,000 years, which have resulted in limited connections to the open sea, negligible tides, low salinities, and reduced floras. The ecology of these two unique saltwater bodies differs from true estuaries like the York River of Maine, the Great Bay Estuary System of New Hampshire/Maine, and the Merrimack River of Massachusetts, which experience extreme hydrographic and tidal variability. Of the 309 total seaweed taxa recorded from the six Northwest Atlantic embayments, Bras d'Or Lake had the lowest number of red, brown, and green algae (i.e., 83) and shared taxa (mean 61.2 ± 4.9 SE), whereas Narragansett Bay had the highest numbers of total (203) and shared taxa (mean 111.6 ± 20.1 SE). Several taxa were restricted to single embayments, with a few glacial and limnic relicts occurring in Bras d'Or Lake and the Baltic Sea. Nine disjunct warm-water taxa were present in Bras d'Or Lake, with this representing the second highest numbers found in four embayments located north of Cape Cod, Massachusetts; this pattern reflects the characteristics of a shallow inland lake. Eleven introduced taxa were recorded from the various Northwest Atlantic embayments, ranging from two in Bras d'Or Lake to 3–10 in the other five embayments. The absence of an intertidal fucoid zone in the Lake (and the Baltic Sea) is probably associated with several physical factors, including a lack of tides, extensive ice-scouring, long-lasting atmospheric reductions of sea level, and reduced salinities. By contrast, the occurrence of subtidal fucoid algae within both brackish water habitats is probably due to a lack of strong competition from perennial kelp populations, which have limited tolerances to low salinities. Morphological features of attached submerged fucoids are analogous to those of loose-lying or entangled salt marsh forms, which are usually small, thin, profusely branched, and have extensive vegetative fragmentation. Unique aegagropilous (detached, ball-shaped) populations of Gracilaria tikvahiae also were found at some inland Bras d'Or Lake sites, presumably resulting from ice scouring and detachment.

Transport of Seaweeds by Tagged Migratory Fish Populations

A striped bass (Roccus saxatilis) that was tagged and released from the Potomac River, Maryland (Chesapeake Bay) was caught within the Great Bay Estuary System (New Hampshire/Maine). It bore a plastic identification tag densely clothed with 12 macroalgae, including 1 species of colonial diatom, 5 green and 6 red algal species. Five of the taxa were perennials and 7 were opportunistic annuals, having extensive reproductive and recruitment capabilities. The occurrence of the cold-temperate red alga Ceramium deslongchampii var. hooperi and 11 broadly distributed taxa suggests that diverse seaweeds can colonize such a surface, depending upon propagule availability within the weter mass at a given time and place

Incidence ofVibrio vulnificusin northern New England water and shellfish

Vibrio vulnificus, an autochthonous inhabitant of the estuarine environment, was detected in water and oysters from the Great Bay Estuary System of New Hampshire and Maine. Previously, it had not been detected north of Boston Harbor on the east coast of the United States. V. vulnificus was detected in water and shellfish samples at five out of ten sites, and only in areas that were not open to recreational shellfishing. Although samples were collected from May into December, V. sulnificus was only detected in shellfish in July and August. Water sampling began in August, and V. vulnificus persisted at one site into October.

Incidence of Vibrio vulnificus in northern New England water and shellfish

Vibrio vulnificus, an autochthonous inhabitant of the estuarine environment, was detected in water and oysters from the Great Bay Estuary System of New Hampshire and Maine. Previously, it had not been detected north of Boston Harbor on the east coast of the United States. V. vulnificus was detected in water and shellfish samples at five out of ten sites, and only in areas that were not open to recreational shellfishing. Although samples were collected from May into December, V. sulnificus was only detected in shellfish in July and August. Water sampling began in August, and V. vulnificus persisted at one site into October.

Tissue Nitrogen and Carbon Variations in New England Estuarine Ascophyllum nodosum (L.) Le Jolis Populations (Fucales, Phaeophyta)

The seasonal patterns ofAscophyllum nodosum (L.) Le Jolis tissue composition (N, C and ash) and ambient inorganic N were measured for 18 months at seven sites throughout the Great Bay Estuary System, New Hampshire-Maine, U.S.A. Overall, the seasonal cycle of tissue N coincided with ambient dissolved inorganic N, with low values in the late spring and summer and highest values in late fall and winter. even so, a pronounced lag occurred in the spring when ambient nutrients decreased, and the levels of tissue N remained high. The seasonal patterns of tissue N were very similar throughout the estuary, although the spring maxima were conspicuously greater at inner than outer estuarine sites. No conspicuous seasonal trend was apparent for tissue C, and the C/N ratios merely reflected variation in N. The percent ash values were extremely variable, and they did not reflect a simple salinity gradient within the Estuary. Two examples of the potential significance ofAscophyllum to the nitrogen pools in northern New England estuaries are discussed.

Intertidal macroalgae and macroinvertebrates: Seasonal and spatial abundance patterns along an estuarine gradient

Quantitative sampling of the dominant intertidal epibiota was conducted seasonally along an estuarine gradient within the Great Bay Estuary System, New Hampshire, U.S.A. The abundance and zonation of the dominant macroorganisms varied with distance into the estuary. Replacement of marine by estuarine species occurred, and overall abundance and species richness decreased along the estuarine gradient. Zonation patterns within the inner estuary were primarily allied with substrata. Maximum abundance of invertebrates occurred in the mid-intertidal zone where a dense fucoid canopy provided habitat heterogeneity. Densities of epibiotic organisms decreased toward low water, especially in the inner estuary where hard substratum was limiting. Settlement blocks, introduced into the low intertidal zone, were dominated by barnacles and fucoid algae; after 16 months, the species composition on the settlement blocks resembled the adjacent community. Semibalanus balanoides settled in the spring, while Fucus vesiculosus var. spiralis exhibited low but constant settlement. Despite the physical rigors of the estuarine environment, only Semibalanus balanoides, Ilyanassa obsoleta and Spartina alterniflora showed significant seasonal changes in density. Thus, there are predictable and persistent epibiotic species assemblages within the intertidal zone of the Great Bay Estuary System.

EFFECTS OF ICE ON ASCOPHYLLUM NODOSUM WITHIN THE GREAT BAY ESTUARY SYSTEM OF NEW HAMPSHIRE‐MAINE12

ABSTRACTThe, effects of ice on Ascophyllum nodosum (L.) Le Jolis within the Great Bay Estuary System of New Hampshire‐Maine, U.S.A. were assessed during the winter of 1980–81. Approximately 50% of the plants late fall standing crop, or an estimated 136 tonnes dry weight, was removed by ice‐rafting. Pieces of Ascophyllum removed averaged 22 cm in length, 15 g in fresh weight and generally represented 2–3 years of growth. Although the winter of 1980–81 wax somewhat extreme, a similar pruning process probably occurs each year contributing to the characteristic bushy habit of attached inner estuarine plants. Ascophyllum fragments rafted in ice and deposited into salt marshes are suggested as a major source of the, ecad scorpioides (Hornemann) Hauck.

Investigations of New England Marine Algae II: The Species Composition, Distribution and Zonation of Seaweeds in the Great Bay Estuary System and the Adjacent Open Coast of New Hampshire

Investigations of New England Marine Algae II: The Species Composition, Distribution and Zonation of Seaweeds in the Great Bay Estuary System and the Adjacent Open Coast of New Hampshire

Nutrient fluxes within a small north temperate salt marsh

The water exchange between a small (4.1 hectare) salt marsh adjoining the Great Bay Estuary system of New Hampshire, USA was sampled during 16 tidal cycles between July, 1976 and November, 1977. Tidal amplitude, temperature, salinity, nutrient concentrations (ammonia-N, nitrate-N, nitrite-N, orthophosphate-P, total-P, silicates) and suspended particulates were measured. Conspicuous tidal hydrographic patterns were observed. Mean concentrations of nitrate-N and silicates varied with season. The tidal information, combined with volume determinations, was extrapolated to determine the net flux of hydrographic parameters on monthly and yearly bases. Ammonia-N showed a pronounced seasonality of net exchange by regression analyses. Ammonia-N and suspended particulates had a statistically significant import into the marsh. However, the net fluxes of the other materials were not statistically different from O.

Seasonal influx and decomposition of autochthonous macrophyte litter in a north temperate estuary

An 18-month study was undertaken to determine the seasonal contribution and detrital processing of autochthonous plant litter in the Great Bay Estuary System of New-Hampshire-Maine, USA and adjacent open coast. Four species were studied: the halophytes, Spartina alterniflora Loisel. and Zostera marina L. and the seaweeds, Ascophyllum nodosum (L.) Le Jolis and Fucus vesiculosus L. v. spiralis Farlow. Monthly strand line collections at estuarine and open coastal sites provided information on the seasonal influx of litter derived from each species. Detrital inputs from S. alterniflora and Z. marina were maximal in the spring and summer, respectively. Seaweed litter was abundant (35 to 85% of the total strand line) throughout the year. The seaweeds contributed 1 to 3 times as much detrital material as the vascular plants within the Estuary, and 50 times as much on the open coast. In situ measurements of decomposition, using nylon, mesh bags, were made for each species under several environmental conditions. Seaweeds decomposed 3 to 10 times faster than vascular plant litter under similar conditions. Decomposition rates and changes in the nutrient content of litter were dependent on surrounding environmental conditions. Continual nutrient depletion occurred in litter within the strand line. Nitrogen and phosphorus enrichment were observed under submerged conditions and were attributed to microbial activity and rapid leaching of carbonaceous substrates. A computer simulation model was developed to validate the field data and to predict seasonal detrital carbon input by each species. The significance of autochthonous input is discussed in relation to other detrital sources.

Contribution of Receptacles from the Fucoid Ascophyllum nodosum to the Detrital Pool of a North Temperate Estuary

The fucoid brown algaAscophyllum nodosum (L.) Le Jolis annually produces lateral reproductive branches (i.e. receptacles) approximately equal in weight to its vegetative thalli. The receptacles are shed within a single month during the spring. The estimated total input of receptacles to the detrital pool within the Great Bay Estuary System of New Hampshire-Maine, U.S.A., is 445 g dry wt·m−2·yr−1. Decomposition rates were rapid with only 50% or less of the original litter remaining after 50 days. Nitrogen and phosphorus flux from the litter bags varied with environmental conditions and habitats.

Seasonal growth and reproduction of estuarine fucoid algae in New England

Estuarine populations of Ascophyllum nodosum (L.) Le Jolis and Fucus vesiculosus L. var. spiralis Farlow from the Piscataqua River of the Great Bay Estuary System (New Hampshire-Maine) showed their maximum growth during the spring and fall of two consecutive years. The maximum growth rates (in terms of elongation) for Ascophyllum and Fucus were 3.5 and 3.6 cm/month, respectively, during 1973, and 3.2 and 2.3 cm/month in 1974. The average length of whole Fucus fronds showed a trend towards longer plants during the early spring and late summer-fall, while the average weight was significantly greater in the spring and early summer. Ascophyllum showed a distinct reproductive periodicity, with a maximum in March or April of both years; after the spring period of maximum reproduction, the receptacles dehisced simultaneously and the plants were vegetative during the summer. The reproductive periodicity of Fucus was not so distinct as that of Ascophyllum; even so, its maximum reproduction was in April of both years. The level of reproduction for Ascophyllum populations was three times greater in 1974 than in 1973. The reproduction and growth of the two fucoid algae are related to seasonal variations in temperature and light.

An ecological study of fucus spiralis L.

An ecological study of Fucus spiralis L. has been made at Jaffrey Point, Newcastle, New Hampshire and the adjacent Great Bay Estuary System from 1972–1975. The distribution, growth, reproductive periodicity, attrition and longevity of the plants are described in relation to a variety of environmental factors. F. spiralis shows a broad but discontinuous estuarine distribution within the Great Bay Estuary System. The presence or absence of appropriate substrata is considered to be a factor determining its discontinuous distribution, since it is usually associated with metasedimentary or metavolcanic rock outcrops. The maximum growth and reproduction of F. spiralis are during the summer. The summer growth rates ranged from 1.9 to 2.8 cm/month while the average growth rate throughout the year was 1.2 cm/month. F. spiralis populations showed two periods of major attrition, namely, during the winter and summer. The average longevity of F. spiralis plants is ≈ 2 yr. The F. spiralis zone lies in the uppermost intertidal area between +2.12 and +2.31 m above M.L.W. There is a micro-stratification of biomass, stature, and reproductive activity within this zone. Average plant weight, length, and fertility tend to decrease with increasing elevation.

Ecological studies of the salt marsh ecad scorpioides (Hornemann) Hauck of Ascophyllum nodosum (L.) Le Jolis

The seasonal and spatial distribution of the free-living ecad scorpioides (Hornemann) Hauck of Ascophyllum nodosum (L.) Le Jolis are described from the Great Bay Estuary System of New Hampshire-Maine, U.S.A. The growth and distribution of ecad scorpioides show a variety of phenological and distributional relationships between A. nodosum and the marsh grass Spartina alterniflora Loiseleur-Deslongchamps. A biomass maximum of ecad scorpioides was found in the fall during two consecutive years; it may be attributable to an influx of source material ( i.e., A. nodosum) after storms, as well as normal seasonal growth of the ecad. Spartina alterniflora provides initial stability for the progenitor fragments of ecad scorpioides and a protective canopy during the summer. Sexual reproduction of the ecad scorpioides was only recorded during one of the three years of study. The morphology and reproduction of ecad scorpioides is compared and contrasted with the attached A. nodosum, as well as with several detached ecads. A gradient of morphology is evident from typical A. nodosum to the extreme ‘marsh’ ecad scorpioides.

Physiological ecology of four Polysiphonia species (Rhodophyta, Ceramiales)

Photosynthesis and respiration of 4 species of the marine red algal genus Polysiphonia were evaluated under a variety of light, temperature and salinity conditions. The manometric results were compared with the local distribution and abundance of each species. The species can be separated into two distinct categories based on their overall distribution and temperature optima: (1) cold water plants [P. lanosa (L.) Tandy and P. elongata (Hudson) Sprengel], with peak photosynthesis at 21° to 24°C, but with active photosynthesis as low as 5°C; (2) plants with warm-water affinities [P. nigrescens (Hudson) Greville and P. subtilissima Montagne], having photosynthetic optima at 27° to 30°C, and exhibiting little or no photosynthesis below 10°C. The plants from the first group exhibit thermal injury at temperatures of 25°C and show a narrow tolerance to low salinities during periods of high temperatures. The plants from the second group show thermal injury at 30°C and have a wider tolerance to low salinities. The horizontal distribution of the 4 Polysiphonia species within the Great Bay Estuary System of New Hampshire, USA, is primarily governed by their tolerances to high temperatures and low salinities. The temperature optimum for each of the species corresponds to its particular estuarine distribution. Thus, P. subtilissima, having the highest temperature optimum, penetrated furthest into the Estuary, while P. lanosa, having the lowest temperature optimum, was restricted to the more coastal stations. There was a good correspondence between the natural distribution patterns and the manometric results.

Ecological studies of economic red algae. III. Growth and reproduction of natural and harvested populations of Gigartina stellata (Stackhouse) batters in New Hampshire

The growth in situ of populations of Gigartina stellata (Stackhouse) Batters has been recorded at three New Hampshire locations and correlated with seasonal and spatial variations of surface salinity, temperature, and nutrients. Annual growth began between February and May, depending upon the location and its hydrographic regime. Gigartina populations reached maximum biomass and size in August and September, and a general decrease in both occurred during the reproductive period from October to February. The period of fastest growth coincided with increasing summer temperatures, while maximum carpospore release occurred during the period of decreasing (coldest) temperatures. The largest plants and maximum biomass of Gigartina were found on the open coast (at a semi-exposed site) while smaller plants and reduced biomass were evident within the Great Bay Estuary System. Salinity is a dominant factor influencing both the local distribution and growth of the plant. Gigartina is primarily restricted to the littoral zone, and its maximum length and biomass occur between +0.45 and +1.0 m above M.L.W.Experimental plots were established to determine the effects of differential levels and seasons of harvesting on G. stellata. Summer (August) harvesting allowed control levels of biomass and population structure to be reached after one year, while winter (December) harvests attained control levels after 19 months. Denuded and sterilized quadrats required more than three years to re-establish themselves. Harvesting in December gave control levels of reproduction in the careful and moderately harvested plots after 9 and 12 months respectively. An August harvest deprived all the plots of reproductive potential until the following reproductive season.