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1.
Brachyuran larvae were sampled every two hours at two depths in Indian River Inlet over six consecutive tidal cycles. Larvae from seven taxa were collected. Three taxa were identified at the level of species. Pinnixa spp. and Uca spp. zoeae were most common at the surface on ebbing tides and were apparently exported to coastal shelf waters. Uca spp. and Callinectes sapidus megalopae were common near the bottom on flooding tides. This would promote retention in the estuary and is consistent with previous reports in the literature. Ovalipes ocellatus, Cancer irroratus and Libinia spp. were most common on flooding tides. This suggests that a pool of these larvae existed in adjacent coastal waters, and that these larvae were carried into the inlet on flooding tides. 相似文献
2.
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 相似文献
3.
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 相似文献
4.
Spatial and temporal variations in the abundances and distributions of oligochaetes of a southwestern Louisiana estuary were examined as part of a long term study of community structure of benthic macroinvertebrates. Quantitative samples were collected at monthly intervals from nine stations for two years and an additional 17 stations were sampled once. A tubificid oligochaete,Tubificoides denouxi n. sp., is described from the five species collected. The two predominant oligochaetes,Tubificoides heterochaetus andT. denouxi, were congeneric and exhibited completely allopatric distributions. Two oligochaete species with-restricted distributions,Monopylephorus helobius andLimnodriloides sp., were sympatric withT. denouxi, whileThalassodrilides belli, although less abundant, was sympatric with bothT. denouxi andT. heterochaetus. Sexually mature specimens ofT. denouxi andT. belli were collected only in the summer,T. heterochaetus was sexually mature in both winter and summer collections, andMonopylephorus helobius was sexually mature in spring and summer collections. Many of the studies of Oligochaeta have concluded that correlation exists between sediment grain size and species demography. Our data demonstrate a strong relationship between salinity and the abundance and distribution of estuarine species.Tubificoides denouxi was found only within the salinity range of 14.8 to 22.0‰ salinity,T. heterochaetus was found only within the range of 2.3 to 14.1‰, andT. belli had a salinity distribution intermediate between the previous species. No relationship was found between sediment grain-size analysis, water depth or hydrographic variables and species distribution. 相似文献
5.
The calanoid copepod community was surveyed semi-monthly, from May to July 1992, at three stations in the Navesink-Shrewsbury rivers system, the southernmost branch of the Hudson-Raritan estuary (New York-New Jersey). The dominant species collected during the survey wasAcartia hudsonica, followed byA. tonsa. A comparison of this survey with three earlier surveys suggests that the calanoid copepod community and relative abundance of dominant species have not changed substantially since the 1960s. Findings from a 1972 study, which noted the absence ofA. hudsonica andPseudodiaptomus coronatus as dominant species, were probably reflecting a temporary situation. The variations may have been related to a change in water quality, caused by an upgrade in sewage treatment, completed just prior to the 1972 survey, and/or resulted from the residual effects of Tropical Storm Agnes on this estuary. 相似文献
6.
The objective of this study was to determine what effect, if any, large pile-supported platforms (piers) have on the habitat distribution and abundance of juvenile fishes. Trapping techniques were used in 1993 and 1994 under piers, in pile fields, and in open-water habitat types in shallow areas (<5 m) in the lower Hudson River estuary (40°44′N, 70°01′W). Nearly 1500 fishes, mostly juveniles, representing 24 species were collected in 1865 trap-days from May through October in the 2-yr study. The presence of relatively large numbers of young-of-the-year (YOY) fish during both years lends support to the idea that shallow areas in the lower Hudson River estuary currently function as nursery habitats for a variety of fishes. Two seasonal assemblages were apparent, but their composition varied somewhat between years.Microgadus tomcod andPseudopleuronectes americanus YOY dominated an early summer assemblage (May–July) while large numbers of YOYMorone saxatilis were collected as part of a late summer assemblage (August–September). The effects of habitat type on fish assemblage structure were significant during both years. Fish abundance and species richness were typically low under piers; YOY fishes were rare andAnguilla rostrata accounted for a large proportion of the total catch. In contrast, YOY fishes dominated collections at pile field and open-water stations, where abundance and species richness were high. These results indicate that habitat quality under the platforms of large piers (>20,000 m2) is probably poor for YOY fishes when compared with nearby pile field and open-water habitat types. 相似文献
7.
This study examined the environmental factors influencing the distribution and abundance of hydrobiid snails in two estuaries on the northeastern coast of Argentina in a coastal lagoon (Mar Chiquita, 37°40′S, 57°20′W) and a partially mixed estuary (Quequén Grande, 38°30′S, 58°45′W). Five intertidal study sites in each estuary represented a gradient in environmental conditions. Variations in the main environmental factors and in the abundance of hydrobiids were assessed both spatially and seasonally. The three species wereHeleobia australis, Heleobia conexa, andHeleobia parchappii, and they were primarily distributed across a salinity gradient. This pattern was clearly recognizable in the partially mixed estuary, where the abundance ofH. australis decreased as salinity decreased, and the abundance ofH. conexa gradually increased towards the inner reaches of the estuary.H. parchappii was restricted to areas far away from the influence of the tide. Slight differences in the distribution patterns of these species between Quequén Grande and Mar Chiquita were refated to the different dynamics of environmental factors in each estuary. 相似文献
8.
John E. Olney 《Estuaries and Coasts》1983,6(1):20-35
The seasonal abundance and spatial distribution of eggs and early larvae of the bay anchovy,Anchoa mitchilli, and the weakfish,Cynoscion regalis, were determined from plankton collections taken during 1971–1976 in the lower Chesapeake Bay. Eggs and larvae of the bay anchovy,Anchoa mitchilli, dominated the ichthyoplankton, making up 96% of the total eggs and 88% of all larvae taken. A comparison of egg and larval densities from the lower Chesapeake Bay to existing data from other East Coast estuaries suggested that Chesapeake Bay is a major center of spawning activity for this species.Anchoa mitchilli spawning commenced in May when mean water column temperatures approached 17°C and abruptly ceased after August. Eggs and early larvae presented a continuous distribution throughout the study area during these months. Eggs and larvae of several sciaenid species, especiallyC. regalis, ranked second in numerical abundance. Larval weakfish were consistently taken in late summer of each sampling year but peak abundance and distribution was observed in August 1971. Sciaenid eggs exhibited a distinct polyhaline distribution with greatest concentrations observed at the Chesapeake Bay entrance or along the Bay eastern margin. Analysis of sciaenid egg morphometry and larval occurrence suggested spawning activity of at least four species. Additional important species represented by eggs and/or larvae in the lower Chesapeake Bay wereHypsoblennius hentzi, Gobiosoma ginsburgi, Trinectes maculatus, Symphurus plagiusa andParalichthys dentatus with the remaining species occurring infrequently. 相似文献
9.
A 16-yr (1985–2000) time series of calanoid copepod (Acartia tonsa andEurytemora affinis) abundance in the upper Chesapeake Bay was examined for links to winter weather variability. A synthesis of sea level pressure
data revealed ten dominant, winter weather patterns. Weather patterns differed in frequency of occurrence as well as associated
precipitation and temperature. The two dominant copepod species responded differently to winter weather variability.A. tonsa abundance showed little response to winter weather and did not vary in abundance during wet or dry springs.E affinis responded strongly to winter weather patterns that produced springs with high freshwater discharge and low salinities. During
wet springs,E. affinis abundance increased overall and its area of dominance extended further down estuary. The different response of the two species
is likely related to several factors including residence time, development time, salinity tolerance, food limitation, and
life history strategy. Important fish species that rely on zo oplankton as food resources were also related to winter weather
variability and spring zooplankton abundance.Morone saxatilis (striped bass) andAnchoa mitchilli (bay anchovy) juvenile indices were positively and negatively correlated toE. affinis abundance, respectively. *** DIRECT SUPPORT *** A02BY003 00004 相似文献
10.
Depth-specific sampling at a single location was used to examine the vertical distribution of pediveliger larvae of bivalve mollusks in the York River, an estuary of Chesapeake Bay, Virginia. The water column at the sampling site was usually well mixed, lacking consistent temperature or salinity gradients for larvae. Four species showed strong vertical stratification when collected simultaneously at three depths. Pediveliger stage larvae of a clam (Cyrtopleura costata), an oyster (Crassostrea virginica), and a shipworm (Bankia gouldi) were most abundant near the benthos, and least abundant near the surface. A mussel (Geukensia demissa), showed the reverse trend, with most pediveliger larvae near the surface. Tidal stage had a slight effect on two species (C. costata andC. virginica), but only to increase the relative abundance of larvae near the benthos during flood tide. Otherwise, neither tidal phase nor light levels (night versus day) had detectable effects on distribution patterns. Sampling very close to the sediment-water interface provided no evidence that pediveliger larvae spent a significant proportion of their time in this location. While the behavior of precompetent bivalve larvae may tend to retain them within an estuary, that of competent-to-metamorphose pediveliger larvae does not appear to have that function. Pediveliger larvae may regulate their depth to best locate potential settlement substrate. Such an hypothesis is consistent with adult habitat zones of at least some of these species in Chesapeake Bay. Removing competent-to-settle larvae from analyses of larval distributions in estuaries will enhance or clarify depth distribution patterns observed for earlier-stage larvae. 相似文献
11.
The seasonal occurrence and relative abundance of larval and juvenile fishes, particularly members of the family Sciaenidae, from a Virginia Atlantic coast estuary were determined from ichthyoplankton and otter trawl collections made from March 1979 to March 1980. The larvae of 19 species in 14 families were identified in the ichthyoplankton. Larvae of the engraulid, Anchoa mitchilli (bay anchovy), and the atherinid, Menidia menidia (Atlantic silverside), dominated the samples and made up 13 and 22%, respectively, of the 9,440 larvae collected. Peak occurrence of all larvae was from May to August. The juveniles of 28 species in 19 families were identified from otter trawl collections. Juvenile sciaenids numerically dominated the trawl collecions and made up 68% of the trawl catch. Juvenile density peaked during September through December. 相似文献
12.
Joseph E. Merz Paul S. Bergman Joseph L. Simonis David Delaney James Pierson Paul Anders 《Estuaries and Coasts》2016,39(5):1526-1536
Abiotic factors and species introductions can alter food web timing, disrupt life cycles, and change life history expressions and the temporal scale of population dynamics in zooplankton communities. We examined physical, trophic, and zooplankton community dynamics in the San Francisco Estuary, California, a highly altered Mediterranean climate waterway, across a 43-year dataset (1972–2014). Before invasion by the suspension-feeding overbite clam (Potamocorbula amurensis) in the mid-1980s, the estuary demonstrated monomictic thermal mixing in which winter turbidity and cool temperatures contributed to seasonally low productivity, followed by a late-spring-summer clearing phase with warm water and peak phytoplankton blooms that continued into early winter. Following the clam invasion, we observed a shift in peak phytoplankton bloom timing, with peak productivity now occurring in May compared to June prior to the invasion. Peak abundance of several zooplankton taxa (Eurytemora affinis, Pseudodiaptomus, other calanoids, and non-copepods) also shifted to earlier in the season. We present the first evidence of a shift in the timing of peak abundance for zooplankton species that are key prey items of delta smelt (Hypomesus transpacificus), a federally threatened pelagic fish species. These timing shifts may have exacerbated well-documented food limitations of delta smelt due to declines in primary productivity since the invasion of the overbite clam. Future conservation efforts in the estuary should consider measures designed to restore the timing and magnitude of pre-invasion phytoplankton blooms. 相似文献
13.
Charles A. Menzie 《Estuaries and Coasts》1980,3(1):38-54
The benthic fauna of a small cove of the Hudson River containing the aquatic plantMyriophyllum spicatum L. was studied for a one-year period. The fauna was characteristic of oligohaline zones of United States east coast estuaries. Total abundance of invertebrates retained on a 0.12 mm mesh sieve averaged 124,631 organisms m?2 (sediment and plant populations combined) and ranged up to 196,000 m?2. During the May–August period, invertebrates living on the plants comprised 16–35% of the invertebrate fauna in the cove. Chironomid larvae were the most abundant organisms on plants and the third most abundant in the sediments. Two assemblages of chironomid species were recognized; one lived solely in the sediments, the other lived primarily on the plants.Chironomus decorus andTanytarsus sp. dominated the former group andCricotopus sylvestris the latter. The chironomidDicrotendipes modestus utilized both habitats. During the May–August period, chironomid biomass on the plants comprised approximately 50% of total chironomid biomass in the cove. The mean dry-weight biomass of chironomids in the cove (1.6 g m?2) is estimated to be sixteen times greater than that of the fauna in the deeper areas of the river. Because chironomid larvae are eaten by fish and invertebrates, shallow water regions with their rich chironomid (and other fauna) may contribute importantly to the trophic dynamics of estuarine systems. *** DIRECT SUPPORT *** A01BY009 00004 相似文献
14.
Fish and decapod entry into small (1.5 m2) artificial seagrass habitats positioned on an open sand area in a New Jersey estuary was examined to determine if immigration varied between day and night. To encounter the structured habitats, colonizers had to cross an expanse of bare sand, with its presumably higher predation risk. Contrasts in abundance in the artificial seagrass plots between dawn and dusk indicated higher nighttime immigration for four species, including the fishesFundulus heteroclitus andMyoxocephalus aenaeus, and the caridean shrimpsPalaemonetes vulgaris andHippolyte pleuracanthus. Size-frequency distributions of colonizers varied between day and night for two fish species,Menidia menidia andSyngnathus fuscus, with a greater proportion of smaller individuals immigrating to the artificial seagrass at night.Callinectes sapidus also displayed a diel contrast in size distribution but, for this species, proportionately more small individuals colonized the plots during the day. We suggest that diel variability in predation risk and/or diel patterns in motor activity may be responsible for these patterns in immigration. 相似文献
15.
Diel vertical migration (DVM) and seasonal timing of three sympatricCancer spp. larvae were investigated in southeastern Alaska. Diel sampling was conducted at a station in Icy Strait at 0400, 0700, 1000, 1300 h in the first day, and 1300, 1600, 1900, and 2200 h in the second day from June to September 2001. Larvae were collected with Bongo nets (333 and 505 μm mesh) towed vertically from 20 m depth to the surface. During flood tides surface temperature increased slightly and salinity decreased; the reverse occurred during ebb tides. Zooplankton biomasses were higher in the early morning and evening than during the midday. A total of 4,482 larvae were examined for the study.Cancer oregonensis larvae were most abundant (4,238), followed byC. magister (205) andC. productus (39). Larval density peaked in June while no larvae were found in September.C. magister larvae had a crepuscular migration; larval abundance peaked in early morning and evening.C. oregonensis larvae comprised 94.6% of allCancer spp. larvae collected and had a strong DVM in June. Earlier zoeal stages ofC. oregonensis were relatively more abundant during midday, while later stages were more abundant at night. In July, later larval stages ofC. oregonensis were distributed at the surface all day with a peak at 2200 h. Larvae ofC. productus first occurred in July and peaked in August.C. productus had DVM but many were at the surface diurnally.C. magister andC. oregonensis larvae co-occurred seasonally as they do in the lower latitudes, e.g., Washington and British Columbia; however,C. productus appeared approximately 2 mo later thanC. magister andC. oregonensis in southeastern Alaska. 相似文献
16.
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 相似文献
17.
Henrique Nogueira Cabral 《Estuaries and Coasts》2000,23(3):351-358
The flatfish community of the Sado estuary was studied based on beam trawl catches in six sampling areas. Temperature and salinity were recorded during surveys and sediment composition was determined at each sampling area. A total of 12 species were identified (1 Bothidae, 1 Pleuronectidae, and 10 Soleidae).Dicologoglossa hexophthalma (Bennett 1831),Microchirus ocellatus (Linnaeus 1758), andSynaptura lusitanica (Capello 1868) were new records to this estuarine system.Monochirus hispidus Rafinesque, 1814, was the most abundant species (about 80% of the total individuals caught). Community structure reflected both spatial and temporal patterns. A longitudinal abundance pattern was noticed with some species much more abundant in outer estuarine areas, namelyM. hispidus, Arnoglossus laterna (Walbaum 1792), andBuglossidium luteum (Risso 1810), while others, such asSolea solea (Linnaeus 1758) andSolea senegalensis Kaup, 1858, presented the highest densities in inner areas. Besides temperature and salinity gradients, species distribution was also influenced by sediment composition. Seasonal variation was mainly determined by the different periods of juvenile peak abundance according to the species which emphasize the role of the estuary as a nursery ground for several flatfish species. 相似文献
18.
Mean daily consumption rates on Mytilus spp. were compared among juveniles of the non-indigenous Carcinus maenas, juveniles of the indigenous Cancer irroratus, and adults of the indigenous Dyspanopeus sayi between June and August 2005 to assess the relative impact of juvenile C. maenas in field (Benacadie Channel (45°54′ N, 60°53′ E), Bras d’Or Lakes, Nova Scotia, Canada) and laboratory experiments. This study examined: (1) whether consumption rates in a field setting vary among species; (2) the effect of laboratory and field settings on species-specific consumption rates, and whether rates vary between settings for each species; and (3) the effects of temperature and salinity on the consumption rates of these species. In field experiments, there was no significant difference in consumption among C. maenas, C. irroratus, and D. sayi (0.100?±?0.067, 0.450?±?0.189, and 0.800?±?0.423 mussels crab?1 d?1, respectively). However, both C. maenas and C. irroratus consumed two to four times more prey in the laboratory than in the field. D. sayi prey consumption was also greater (although not significant) in the laboratory than in the field. In the laboratory, consumption rate was greater for C. irroratus in salinities of 26 than 17 (2.75 and 1.69–1.81 mussels crab?1 d?1, respectively), and in 17°C than 13°C (1.10–1.21 and 0.56–0.64 mussels crab?1 d?1, respectively) for C. maenas. In all experiments, consumption rates of juvenile C. maenas were lower than or similar to those of the juvenile and adult indigenous species, suggesting that the potential predatory impact of juvenile C. maenas on Mytilus spp. may not be as significant as that of the adults of this non-indigenous species. 相似文献
19.
Distribution and abundance of flatfish species (<150 mm standard length) were related to habitat characteristics in the Newport River and Back Sound estuaries in North Carolina. Salinity, turbidity, depth, distance from marsh edge, benthic composition, and grain size were used to describe the different shallow water habitats from April through October 1994. One Scophthalmidae, seven Paralichthyidae, one Achiridae, and one Cynoglossidae species were collected during the study including juvenileParalichthys albigutta (gulf flounder),P. dentatus (summer flounder), andP. lethostigma (southern flounder) along with multiple age classes ofCitharichthys spilopterus (bay whiff),Etropus crossotus (fringed flounder),Symphurus plagiusa (blackcheek tonguefish), andTrinetes maculatus (hogchoker). Incidental catches ofAncylopsetta quadrocellata (ocellated flounder),C. macrops (spotted whiff), andScopthalmus aquosus (windowpane) were also made. Flatfish distributions among habitats varied by species, size within species, and season. Regardless of season, the highest densities of flatfishes were found in the upper estuary. All habitats were used by one or more species and most species occurred at several habitats. Some species were significantly more abundant at specific habitat types. Ontogenetic shifts in habitat utilization were found for several species. High densities of smallP. lethostigma, C. spilopterus, S. plagiusa, andT. maculatus occurred in the upper estuary on muddy substrates. LargeP. dentatus, C. spilopterus, S. plagiusa, andT. maculatus utilized sand flats and channels in the lower estuary. 相似文献
20.
Seasonal occurrence patterns within the Mobile Bay estuary, Alabama, of five species of cumaceans are described.Oxyurostylis smithi was most abundant, followed byLeucon americanus, Cyclaspis varians, Eudorella monodon andAlmyracuma proximoculi. With the exception of the oligohalineA. proximoculi, the cumaceans encountered within the estuary are euryhaline marine species that are most abundant at the lower bay stations and that utilize the estuary only when environmental conditions are favorable. 相似文献