Distribution and abundance of macroinvertebrates on certain connecticut tidal marshes,with emphasis on dominant molluscs

The distribution of macroinvertebrates on Connecticut tidal marshes corresponds well with that reported for other marshes along the Atlantic and Gulf coasts of the United States. The greatest densities and biomass of the ribbed mussel,Geukensia demissa, were found on marshes in the central and western part of the state where both the annual production ofSpartina alterniflora and tidal range are large. *** DIRECT SUPPORT *** A01BY019 00011     

A comparison of dispersal strategies in two genera of brachyuran crab in a secondary estuary

Seasonal occurrence and vertical distribution of larvae of two genera of brachyuran crab were studied in a secondary estuary flowing into Delaware Bay. Spawning in the xanthid crabRhithropanopeus harrisii occurred earlier with peak abundance of larvae in June and with a distinct decline in abundance in August. In contrast,Uca spp. larvae reached peak abundance in August. All zoeal stages ofR. harrisii were collected in the river suggesting that larvae of this species are retained in secondary estuaries near areas of prime adult habitat. Only zoea stage I larvae and megalopa ofUca spp. were collected in the river indicating that larvae of these speies may be flushed into the Delaware Bay and may not return to secondary estuaries near areas suitable for adult habitat until the megalopa stage is reached. It is not clear if this dispersal pattern is an active or passive process. *** DIRECT SUPPORT *** A01BY019 00004     

Asiatic clam (Corbicula manilensis) and other foods used by waterfowl in the James River,Virginia

Corbicula manilensis was found in the gizzards of 24 ducks of 5 species taken from the James River, Virginia, between 1973 and 1976. Percent average volume in these species ranged from trace to 6%. This is the first known occurrence of this exotic clam in the food of duck in Chesapeake Bay. A total of 135 other food items was identified from the 116 gizzards of 9 species that were examined. Food that predominated includedCyperus spp.,Leersia oryzoides, Polygonum spp., andZea mays. The great diversity of food consumed in this fresh tidal section of the James River indicates the high value of these wetlands to waterfowl. *** DIRECT SUPPORT *** A01BY015 00008     

The unique,widely distributed,estuarine sea anemone,Nematostella vectensis Stephenson: A review,new facts,and questions

The small, burrowing, edwardsiid sea anemone Nematostella vectensis is widely distributed in estuaries and bays. Most typically it occurs in pools in marshes though it may occur subtidally as well. We have compiled records of its occurrence in North America from Nova Scotia to Georgia along the shores of the Atlantic Ocean, from Florida to Louisiana in the Gulf of Mexico and from California to Washington on the Pacific coast. To date we have found no records of its presence in Alabama or Texas, though it is present in all other of the contiguous coastal states of the United States. The species also occurs in England. We have obtained living specimens from many locations and have crossed females from England, Maryland, Georgia, California, Oregon, and Washington with males from Nova Scotia, Maryland, Georgia, and Oregon. These 24 crosses all yielded viable first-generation anemones that in turn produced second-generation animals. We accept this as proof that this widely distributed anemone is a single species. We have obtained living N. vectensis from 11 areas. Of these, only samples from Maine, Maryland, Georgia, and Oregon contained both sexes. The sample from Nova Scotia was all male and our samples from England, New Hampshire, California, and Washington were all female. We hypothesize that the unisexual samples were from clones resulting from asexual reproduction in this species. *** DIRECT SUPPORT *** A01BY066 00015     

The use of infauna by juvenile Penaeus aztecus Ives and Penaeus setiferus (Linnaeus)

Penaeus aztecus Ives, the brown shrimp, and Penaeus setiferus (Linnaeus), the white shrimp, co-occur in Texas salt marshes as juveniles. Although their life cycles are similar, evidence indicates that the species utilize different resources for the primary faunal element of their diets. Prey selection and growth studies have shown that brown shrimp successfully remove infauna from natural sediment. Further, a diet of polychaetes, whether alone or in combination with algae, produced growth in the species. Brown shrimp appear to be trophically linked to infaunal populations, thus the structure and dynamics of the benthic community may directly affect local brown shrimp productivity. Areas dominated by surface-dwelling polychaetes as opposed to deep burrowers may provide more accessible foraging opportunities for juvenile brown shrimp. By contrast, white shrimp neither removed infauna nor grew to a significant degree when provided polychaetes or amphipods as food. White shrimp are omnivorous but do not rely on infaunal material to the same extent as brown shrimp. The primary faunal element in the diet of white shrimp has not yet been identified. The dietary differences between the two species may play a role in determining which species dominates in regions with varying marsh accessibility. Although not the only factors influencing penaeid survival and growth, prey choice and availability may greatly affect production and local success of penaeid populations. *** DIRECT SUPPORT *** A01BY081 00013     

A method for measuring ingestion rate of deposit feeders and its use with the polychaeteNereis succinea

In situ ingestion rates of some infaunal deposit feeders can be determined without collecting feces by labeling the sediment with fluorescent particles and using these to trace ingested material through the gut of the animals. This technique was applied to the polychaeteNereis succinea and showed that ingestion rate, expressed as material ingested per body weight, increased with temperature and decreased with body size. Total annual ingestion of sediment and detritus for aN. succinea population in a salt marsh near Beaufort, N.C., was estimated to be 5 kg of dry material m^?2, more than 4 times that reported for salt marsh epifaunal deposit feeders. *** DIRECT SUPPORT *** A01BY009 00005     

The introduction and spread of smooth cordgrass (Spartina alterniflora) in South San Francisco Bay

Spartina alterniflora was first introduced into south San Francisco Bay in the 1970’s. Since that time it has spread to new areas within the south bay and is especially well established at four sites. The spread of this introduced species was evaluated by comparing its vegetative and reproductive characteristics to the native cordgrass, Spartina foliosa. The characters studied were intertidal distribution, phenology, aboveground and belowground biomass, growth rates, seed production, and germination rates. Spartina alterniflora has a wider intertidal distribution than S. foliosa and outproduced the native cordgrass in all aspects that were studied. These results indicate that the introduced species has a much better chance of becoming established in new areas than the native species, and once established, it spreads more rapidly vegetatively than the native species. Spartina alterniflora is likely to continue to spread to new areas in the bay and displace the native plant. In addition, this introduced species may effect sedimentation dynamics, available detritus, benthic algal production, wrack deposition and disturbance, habitat structure for native wetland animals, benthic invertebrate populations, and shorebird and wading bird foraging areas. *** DIRECT SUPPORT *** A01BY058 00013     

Spawning origin of small,late-hatched Atlantic herring (Clupea harengus) larvae in a Maine estuary

Atlantic herring (Clupea harengus) larvae have been collected for resource monitoring purposes in the Sheepscot River in mid-coastal Maine during October–February, for the past 20 years. During this period, the larval population in the river has typically peaked in October-early November and has been composed of larvae derived from August–September spawning in eastern Maine and New Brunswick waters and from September-early October spawning along the central Maine coast. Larvae from eastern coastal spawning areas are transported to the river by the prevailing westerly coastal current. The appearance of small (≤15 mm SL) larvae in the river during December and January 1985–1989 suggested an additional time and area of origin. Aging procedures based on enumeration of daily otolith increments showed the majority of these small larvae were spawned from mid October to mid November when spawning usually occurs in western Maine coastal waters and in the vicinity of Jeffreys Ledge. Comparison of back-calculated hatching dates for small larvae collected in the river with wind direction and velocity data from mid October through November suggested that larvae were transported eastward against a weakened Gulf of Maine coastal current to the Sheepscot River by complex wind-driven surface currents that occur off the western Maine coast in the fall. *** DIRECT SUPPORT *** A01BY059 00003     

Secondary production of the amphipod Ampelisca abdita mills and its importance in the diet of juvenile winter flounder (Pleuronectes americanus) in Jamaica Bay,New York

The benthic amphipod Ampelisca abdita dominates mudbottom benthic communities in Jamaica Bay (New York). In this study, we investigated the trophic role of Ampelisca in relation to winter flounder (Pleuronectes americanus) populations—the most frequently trawled fish species in Jamaica Bay. Flounders collected by trawl during summer 1989 were primarily juveniles. Stomach analyses indicated that amphipod crustaceans contributed >99% of prey individuals, with A. abdita making up 88%. Density and size frequency analyses of Ampelisca at three sites indicated two overlapping cohorts: a spring cohort released in June and a summer cohort released in late summer. Most overwintering survivors come from the summer cohort. Secondary production of Ampelisca was estimated at three sites using the cohort summation of biomass method. Estimates of annual production ranged from 25 g DW to 47 g DW m^?2 (mortality + residual biomass); production due to growth ranged from 20 g DW to 26 g DW. Simulations of spring cohort production using a range of plausible growth and mortality schedules suggested that P∶B may be more sensitive to variability in survivorship than growth. Ampelisca secondary production in Jamaica Bay is compared with other amphipod species and with macrobenthic production in other coastal and estuarine systems. We conclude that observed amphipod production is probably more than sufficient to support local winter flounder populations in Jamaica Bay, and we speculate that high nutrient loadings may indirectly stimulate amphipod production. *** DIRECT SUPPORT *** A01BY058 00010     

Dispersion of the salt-marsh periwinkle Littoraria irrorata: Effects of water level,size, and season

This paper documents horizontal and vertical dispersion patterns of a Texas population of the saltmarsh periwinkle, Littoraria irrorata, over a 15-month period. The study was conducted within a tidal marsh on the Anahuac National Wildlife Refuge in Galveston Bay. Two mark-recapture experiments demonstrated that L. irrorata rarely move more than 2 m from their release point over long periods of time and do not home to individual Spartina plants. Adult L. irrorata forage farther away from the base of Spartina stalks at low tide than do juvenile snails. Remaining near the plant base may decrease both temperature and desiccation stress on juveniles. During warm months, L. irrorata climb grass stalks with tidal inundation and forage on the substratum at low tide. Snails are inactive and aggregate in detrital debris at the base of Spartina clumps during the winter. *** DIRECT SUPPORT *** A01BY058 00016     

Seasonal abundance and vertical distribution of crab larvae in Delaware Bay

Larvae of 15 species or genera of crabs were collected and identified during a six month (May 26 to October 28, 1978) study in the mouth of Delaware Bay. Seasonal abundance and vertical distribution of each species were investigated. Most species studied had peak abundance in July and August except forCancer irroratus andOvalipes ocellatus which showed peak occurrence in May and June, respectively. Larvae of species strongly dependent on estuarine habitats, such asUca spp.,Pinnixa chaetopterana, andP. sayana, showed a tendency to congregate in near-bottom waters where net flow of water is landward, thus favoring retention within the estuary. Larvae ofOvalipes ocellatus, Cancer irroratus, andCallinectes sapidus were more common at the surface. This vertical distribution suggests that these larvae are flushed out of the estuary. The mechanisms of recruitment and replenishment of adult populations within the estuary would therefore depend on migration of megalopa and juveniles. *** DIRECT SUPPORT *** A01BY019 00006     

Nutrient pore water chemistry,Great Bay,New Hampshire: Benthic fluxes

Benthic fluxes of C, N, P and Si have been measured at two sites in Great Bay Estuary, New Hampshire. Higher fluxes of reactive phosphate, nitrate and reactive silicate were observed at the site where bioturbation is known to occur and the fluxes of NH₄ ⁺, PO₄ ^?3 and reactive silicate at this location were from 3 to 6 times higher than that calculated by simple pore water diffusion models. *** DIRECT SUPPORT *** A01BY019 00010     

Recruitment of juvenile marine fishes to seagrass habitat in a temperature Australian estuary

We investigated the relationship between distance from the ocean and the recruitment of ocean-spawned juvenile fish to seagrass shallows within marine dominated Lake Macquarie, a coastal barrier lagoon in Southeast Australia. Samples were taken by seine net every 6 wk between June 1986 and June 1987, at 20 sites established at various distances from the entrance channel. The fish fauna was diverse: 80 species from 39 families were caught, with the Gobiidae, Monacanthidae, Syngnathidae, Tetraodontidae, Mugilidae, Atherinidae, Clupeidae, Mullidae, Sparidae, and Blenniidae being well represented. Ambassis jacksoniensis, Atherinomorus ogilbyi, and Gerres subfasciatus accounted for 46% of all individuals. Thirty-two species were classified as ocean spawners, 38 as lagoon spawners, and 10 as unknown in terms of spawning area. Newly settled juveniles of ocean spawners were concentrated near the lagoon's entrance, where most recruited in spring. This pattern occurred in the absence of a salinity gradient: distance from the ocean coupled with weak internal water circulation appears to limit larval distribution and hence juvenile recruitment. Small juveniles of Rhabdosargus sarba were sufficiently abundant for their subsequent dispersal to be directly traced. On the basis of results for this species, and indirect evidence of dispersal for several others, it is suggested that ocean-spawned juveniles, after settling near the entrance, gradually disperse as they grow and change their habitat. Thus, further from the entrance, their recruitment to seagrass shallows is later, at larger sizes, and in smaller numbers. Newly settled juveniles of lagoon spawners, however, were widely distributed within the lagoon. The optimal recruitment of ocean-spawned juveniles to similar coastal lagoons may depend on suitable habitat being available near the entrance. *** DIRECT SUPPORT *** A01BY081 00003     

Stratification and bottom-water hypoxia in the Pamlico River estuary

Relationships among bottom-water dissolved oxygen (DO), vertical stratification, and the factors responsible for stratification-destratification in this shallow, low tidal-energy estuary were studied using a 15-yr set of biweekly measurements, along with some recent continuous-monitoring data. Hypoxia develops only when there is both vertical water-column stratification and warm water temperature (>15°C). In July, 75% of the DO readings were <5 mg 1^?1, and one-third were <1 mg 1^?1. Severe hypoxia occurs more frequently in the upper half of the estuary than near the mouth. Both the time series data and correlation analysis results indicate that stratification events and DO levels are tightly coupled with variations in freshwater discharge and wind stress. Stratification can form or disappear in a matter of hours, and episodes lasting from one to several days seem to be common. Estimated summertime respiration rates in the water and sediments are sufficient to produce hypoxia if the water is mixed only every 6–12 d. There has been no trend toward lower bottom water DO in the Pamlico River Estuary over the past 15 yr. *** DIRECT SUPPORT *** A01BY059 00002     

The estuarine clamRangia cuneata as a biomonitor of dioxins and furans in the Neches River,Taylor Bayou,and Fence Lake,Texas

Polychlorinated dibenzo-para-dioxins (PCDDs) and dibenzofurans (PCDFs) were measured in the tissues of the estuarine clamRangia cuneata at four sites in the Neches River that had been subjected to paper mill effluent and at two remote sites. One of the river samplings was taken before dioxin control measures and another 2 yr after the control measures began. Measurable concentrations of PCDD/Fs were present at all sites, but higher concentrations were present at the Neches River sites. Whole tissue concentrations of 2,3,7,8-tetrachlorodibenzo-para-dioxin (TCDD) and all PCDD congeners for the two collections were not significantly different (p>0.05), but lipid-normalized concentrations for the two collections were significantly different (p<0.05). Highest concentrations of PCDDs at sites located 8 km and 16 km upriver from the paper mill effluent outfall indicated that the materials were transported upriver by saltwater intrusion and/or that nonpoint sources existed upriver. The presences of PCDD/Fs in clam tissues from the remote sites also indicated that other sources of these materials existed. Even under extreme physiological conditions (spent reproductive phase, low lipid contents, water temperature 10°C; ripe reproductive phase, high lipids, water temperature 32°C)Rangia cuneata was an effective biomonitor to determine the distribution of PCDD/Fs at specific sites. *** DIRECT SUPPORT *** A01BY069 00021     

The macroinfaunal community of a tropical estuarine lagoon

The benthic macroinfauna of Lagunal Joyuda, a coastal lagoon in Puerto Rico, was surveyed for two years. Seven hundred fifty core samples yielded 23 macrobenthic taxa. The oligochaeteThalassodrilides gurwitschi comprised 43.4% of the number of individuals collected. Polychaetes comprised 35.4% of the individuals, includingCapitella cf.capitata, Dasybranchus lumbricoides, andSteninonereis martini in approximately equal numbers. The amphipodGrandidierella bonnieroides made up 11.5% of the community. The lagoon yielded fewer species than other tropical estuaries in the Caribbean and Atlantic, but the trophic composition, mostly deposit feeders, was similar. Seasonal patterns in the abundance of individuals were most pronounced in the central basin, with maximum number of organisms during the wet season, and a minimum in the dry season. Responses to rainfall events, however, were variable and probably related to migration patterns in predators. Macrofaunal biomass demonstrated a high degree of annual variation at all sampling stations with a marked increase in 1987. Low macrofaunal biomass, lack of temporal association with physical-chemical conditions, and inverse relationships with predator populations suggest that patterns of macrofaunal abundance in Laguna Joyuda are mediated primarily by biotic mechanisms. *** DIRECT SUPPORT *** A01BY050 00006     

Attempted hybridization of the grass shrimpPalaemonetes (Caridea,palaemonidae) with an evaluation of taxonomic characters of juveniles

Variation in morphological characters used to distinguish the three sympatric species ofPalaemonetes, i.e.,P. pugio, P. intermedius, andP. vulgaris, is suggestive of natural hybridization. Interspecific crosses among the species and intraspecific crosses of allopatric populations ofP. pugio were made to determine whether hybridization was feasible and to evaluate taxonomic characters of the juveniles. No interspecific matings produced larvae in the laboratory. Larvae, from intraspecific matings ofP. pugio andP. vulgaris were reared to 40 days of age. Larval survival rates, development time, and postlarval length ofP. pugio andP. vulgaris were not different, but juveniles ofP. pugio at 40 days after hatching were larger than those ofP. vulgaris. At 40 daysP. pugio had developed adult diagnostic features. However,P. vulgaris displayed sufficient variation in adult diagnostic features to resembleP. pugio in some cases. The intraspecific matings ofP. pugio from widely separated populations were fertile, but there was some indication of reduced reproductive compatibility in crosses involving Virginia females and Florida males relative to intrapopulational controls. *** DIRECT SUPPORT *** A01BY019 00002     

The potential impact of herbivores on the susceptibility of the marsh plantSagittaria lancifolia to saltwater intrusion in coastal wetlands

The objective of this study was to experimentally evaluate the effects of simulated herbivory on the ability of a freshwater marsh plant to recover from temporary saltwater intrusion such as can be caused by tropical storms. Sods containingSagittaria lancifolia, a dominant plant in interior coastal marshes, were manipulated in the field so as to subject plants to a pulse of 15‰ salt water for a duration of 1 wk. In addition to the exposure to salt water, some plants were also subjected to both short-term and long-term flooding treatments of 20 cm, and to simulated herbivory (clipping). Following exposure to salt water, plants were allowed to recover over the winter and were harvested the next June. Neither simulated herbivory, nor salinity, nor flooding caused any long-term effect either singly or in pairwise combinations. However, when plants were subjected to herbivory, salt water, and flooding simultaneously, reduced growth and plant death occurred. These results suggest that high levels of grazing by herbivores may increase the susceptibility of coastal marsh plants to damage from saltwater intrusion. *** DIRECT SUPPORT *** A01BY073 00002     

Biomass and productivity of three phytoplankton size classes in San Francisco Bay

Primary productivity of three size classes of phytoplankton (<5 μm, 5–22 μm, >22 μm) was measured monthly at six sites within San Francisco Bay throughout 1980. These sites in the three principal embayments were chosen to represent a range of environments, phytoplankton communities, and seasonal cycles in the estuary. Temporal variations in productivity for each size class generaly followed the seasonality of the corresponding fraction of phytoplankton biomass. The 5–22 μm size class accounted for 40 to 50% of the annual production in each embayment, but production by phytoplankton >22 μm ranged from 26% in the southern reach to 54% of total phytoplankton production in the landward embayment of the northern reach. A productivity index is derived that predicts daily productivity for each size class as a function of ambient irradiance and integrated chlorophylla in the photic zone. For the whole phytoplankton community and for each size class, this index was constant and estimated as ?0.76 g C m^?2 (g chlorophylla Einstein)^?1. The annual means of maximum carbon assimilation numbers were usually similar for the three size classes. Spatial and temporal variations in size-fractionated productivity are shown to be primarily due to differences in biomass rather than size-dependent carbon assimilation rates. *** DIRECT SUPPORT *** A01BY034 00005     

The trophic consequences of oyster stock rehabilitation in Chesapeake Bay

There is mounting speculation that overharvesting of oyster stocks (Crassostrea virginica) in Chesapeake Bay may be a factor contributing to the decline in water quality and shifts in the dominance of species inhabiting the estuary. The trophic consequences of increasing the oyster population may be addressed using a simple quasi-equilibrium, mass action model of the exchanges transpiring in the Chesapeake mesohaline ecosystem. According to output from the model, increasing oyster abundance would decrease phytoplankton productivity as well as stocks of pelagic microbes, ctenophores, medusae, and particulate organic carbon. Recently acquired field data on phytoplankton productivity, bacterioplankton, and labile organic carbon in the vicinity of rafted oyster aquaculture support model predictions. The model also indicates that more oysters should increase benthic primary production, fish stocks, and mesozooplankton densities. Hence, augmenting the oyster community by restoring beds or introducing raft culture represents a potentially significant adjunct to the goal of mitigating eutrophication through curtailment of nutrient inputs. *** DIRECT SUPPORT *** A01BY059 00005