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1.
A population of the invasive musselMusculista senhousia was monitored bimonthly from May 1999 through April 2000 in the Sacca di Goro, a brackish lagoon of the Po River Delta, Northern Adriatic Sea, in order to give information on the gametogenic cycle, population dynamics, and secondary production of this successful invader. The gonad underwent 4 different stages: spent (December to February), developing (March to May), ripe (June to August), and spawning (September to November). The population was numerically dominated by a single cohort of individuals for most of the year. The mean size of this cohort rapidly increased to 24–25 mm shell length, after which growth slowed and mussels rarely grew larger than 30–32 mm. Summer anoxia may have greatly reduced mussel abundance; annual cohort mortality was 95%. No recruitment was registered on the bed until February 2000, and there was a large pulse of new recruits in April when two cohorts were clearly recognizable. The established bed was the primary site for new recruitment. Secondary production, calculated with two different methods, gave comparable estimates; P:B ratios were 1.5 and 1.7.M. senhousia beds seemed to facilitate the presence of other macrofaunal taxa: abundance of some species (a small gastropod, amphipods, and tube-building polychaetes) were significantly higher within mussel mats at two sites sampled in May 2000 than they were in soft-sediments ∼100 m away.  相似文献   

2.
The temporal variability in abundance and population structure of the gastropodChilina ovalis Sowerby was studied in the upper intertidal zone of Queule River estuary, south-central Chile (c. 40°S). Snails were collected monthly (September 1995–December 1997) from haphazardly-located quadrats (50×50 cm, n=5 each time), and counted and measured (shell height) in the laboratory. Water and sediment samples were collected at the same time to study the snail's habitat characteristics. Overall mean abundance was 115 individuals m?2 (SD=55). Monthly abundance estimates indicated a clear decrease during 1997. This decrease appeared to be related to the annual recruitment success of the species and at least partially to water temperature and sedimentological variability. Overall size range ofC. ovalis was 1.5–27.5 mm shell height. Growth varied seasonally with highest growth rates observed after recruitment (November–February). Slower growth continued throughout the austral winter months. Despite changes in abundance between 1996 and 1997, no differences were detected when population growth estimates were compared between years. A maximum longevity of approximately 4 yr was estimated from the growth curves of the cohorts, and a life cycle with more than one reproductive period is suggested.  相似文献   

3.
The relationships between egg production (spawning behavior), larval growth and survival, and environmental conditions that larvae encounter were investigated in the Patuxent River tributary of Chesapeake Bay in 1991. Striped, bass (Morone saxatilis) eggs and larvae occurred predominantly above the salt front where conductivity was ≤800 μmhos cm?1. There were three prominent peaks in egg production, each coinciding with increasing temperatures. Estimated growth rates of 6-d, otolith-aged cohorts, which ranged from 0.15 mm d?1 to 0.22 mm d?1 (mean=0.17 mm d?1), were not demonstrated to differ significantly from each other. Observed zooplankton densities and temperature did not significantly affect growth rates. Stage-specific cumulative mortalities of combined cohorts were calculated for eggs (Zstage=0.20=18.1%), yolk-sac larvae (Zstage=5.80=99.7%), and first-feeding larvae (Zstage=2.95=94.8%). The very high mortality of yolk-sac larvae suggests that dynamic during this stage may have had a major impact on subsquent recruitment. Cohort-specific mortality rates of larvae were variable, ranging from Z=0.045 d?1 to 0.719 d?1, and were strongly temperature-dependent. Cohorts that experiented average temperature <15°C or >20°C during the first 25 d after hatching had significantly higher mortality rates than those which experienced intermediate temperatures. Estimated hatch-date frequencies of larvae ≥8 mm SL indicated goo, very good, and very low potential recruitments for cohorst spawned during early-season (April 2–11), mid-season (April 12–24) and late-season (April 25–May 5), respectively. Because seasonal temperature trends and fluctuations are unpredictable, striped bass females cannot select a spawning time that guarantees their offspring will be exposed to optimum temperatures. Consequently, selection may have occured for spawning over a broad range of temperatures and dates, a behavior insuring that some larval cohorts will encounter favorable temperatures.  相似文献   

4.
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  相似文献   

5.
Invertebrate predation has been cited as the major factor determining post-settling survival of the soft-shell clam, Mya arenaria. Feeding studies on common mummichogs, Fundulus heteroclitus, in Essex Bay, Massachusetts, from July 1976 to June 1978 showed soft-shell clams to be an important diet item in fish greater than 55 mm TL. Biweekly quantitative seining from 16 April to 24 September 1977 revealed predation peaks in the spring and fall corresponding to March–April and June–July spawning periods for M. arenaria. In spring and fall 1977 and spring 1978, 38.5% of the male and 52.8% of the female mummichogs sampled over 55 mm TL averaged 6.77 and 7.32 clams per stomach respectively. The maximum number of clams per stomach was 49 (108 mm female), and 47 (100 mm male). Quantitative seining at low tide yielded mummichog densities from 0.35 to 6.04 fish/m2. Combining mummichog density estimates with soft-shell clam predation data gave a possible consumption of 546,000 M. arenaria per km low tide shoreline per day during peak predation periods. Results indicate mummichog predation may equal or exceed invertebrate predation as a major cause of small (<12 mm) soft-shell clam mortality in the Gulf of Maine.  相似文献   

6.
In this study, the impact of four-dimensional data assimilation (FDDA) analysis nudging is examined on the prediction of tropical cyclones (TC) in the Bay of Bengal to determine the optimum period and timescale of nudging. Six TCs (SIDR: November 13–16, 2007; NARGIS: April 29–May 02, 2008; NISHA: November 25–28, 2008; AILA: May 23–26, 2009; LAILA: May 18–21, 2010; JAL: November 04–07, 2010) were simulated with a doubly nested Weather Research and Forecasting (WRF) model with a horizontal resolution of 9 km in the inner domain. In the control run for each cyclone, the National Centers for Environmental Prediction (NCEP) Global Forecast System (GFS) analysis and forecasts at 0.5° resolution are used for initial and boundary conditions. In the FDDA experiments available surface, upper air observations obtained from NCEP Atmospheric Data Project (ADP) data sets were used for assimilation after merging with the first guess through objective analysis procedure. Analysis nudging experiments with different nudging periods (6, 12, 18, and 24 h) indicated a period of 18 or 24 h of nudging during the pre-forecast stage provides maximum impact on simulations in terms of minimum track and intensity forecasts. To determine the optimum timescale of nudging, two cyclone cases (NARGIS: April 28–May 02, 2008; NISHA: November 25–28, 2008) were simulated varying the inverse timescales as 1.0e?4 to 5.0e?4 s?1 in steps of 1.0e?4 s?1. A positive impact of assimilation is found on the simulated characteristics with a nudging coefficient of either 3.0e?4 or 4.0e?4 s?1 which corresponds to a timescale of about 1 h for nudging dynamic (u,v) and thermodynamical (t,q) fields.  相似文献   

7.
The infaunal polychaeteNephtys incisa is a dominant constituent of soft-bottom communities in nearshore New England waters. This study quantifies its population ecology under natural conditions and following disturbance (dredge material disposal). Five stations in central Long Island Sound (SREF, 1000E, 400E, 200E and CNTR) representing a gradient of increasing exposure to disposed materials were sampled quarterly for 26 months between May 1982 and June 1984. Population abundances declined continually for 2 years (from approximately 1,500 to 200 individuals m?2) following a peak of high recruitment. At CNTR, the population was decimated following disposal, and thereafter densities remained significantly below other stations. Population size-structure shifted from juvenile domination during the period of high abundance to adult domination as numbers declined. However, numbers of adults declined at 200E and CNTR following disturbance, relative to size-structure changes at other stations. Based on analyses of size-frequency distributions and tooth-rings in the jaws of individualN. incisa, eight cohorts (age-classes) were distinguished during the study period ranging from 3 months to 5 years in age. Growth was spatially and temporally variable; the average growth rate was approximately 15–20 mm (length) a year. Individual growth in most cohorts declined at 200E following disposal. Adults were reproductively active throughout the year, with two peaks in egg production, generally in the spring and fall. There were, however, spatial variations in the spawning cycle, which could influence larval recruitment. Results indicate that ambient population ofNephtys cicasa may go through several population “phases” resulting from temporal and spatial fluctuations in recruitment, individual growth and reproductive activity.Nephtys incisa's response to disturbance may depend on which phase the population is in at the time of disturbance (internal population conditions such as age/size structure) and factors external to the population (e.g., environmental influences on settlement and recruitment and/or the nature of the disturbance). Over 14 months of study, disposal of highly polluted dredge material had a negative impact on several population characteristics ofN. incisa at or near the disposal site (0 to 200 m away), but little or no effects on populations were detected 400 m to approximately 3 km away from the disposal area.  相似文献   

8.
Tidewater silversides,Menidia peninsulae (Goode and Bean) were maintained in 1.3 m diameter holding tanks in identical laboratory recirculating systems. During two weeks under constant conditions (a current velocity of 8 cm per s and continuous illumination, 24L:0D) there was a low relative frequency of arrhythmic spawning. In the subsequent two-week period, fish in one pair of tanks, were maintained under the singular influence of twice daily interruptions in current velocity (8 to 0 cm per s at 0600–0700 and 1800–1900) with continuous illumination. The relative frequency of spawning remained low and there was no evidence of a daily spawning rhythm. However, the mean number of eggs per spawn increased substantially. Fish in the second holding system were subjected to a diel light cycle of 13L:11D with a constant current velocity of 8 cm per s for two weeks. The relative frequency of spawning remained low, and there was no indication of spawning rhythmicity; moreover, there was only a slight increase in the mean number of eggs per spawn. During the third two-week period, fish in the first pair of tanks were provided a 13L:11D diel light cycle, in conjunction with preexisting twice daily interruptions in current velocity; those in the second pair of tanks were provided twice daily interruptions in current velocity in conjunction with the preexisting 13L:11D light cycle. Under the combined influence of interrupted current velocity and diel light cycle cues, there was a marked increase in the relative frequency of spawning in both pairs of tanks. Fish manifested a discernible spawning periodicity, spawns typically occurred between 1800 and 2400; the mean number of eggs per spawn also increased. When fish were returned to constant conditions, current velocity 8 cm per s and 24L:0D for two weeks, the frequency of spawning decreased and there was no indication of a spawning periodicity. Results of another experiment (interrupted current at 1200 to 1300 and 2400 to 0100 with a 13L:11D light cycle) indicated gradual expression of a tidal spawning rhythm during nighttime, 2400 to 0359. Our laboratory results indicate thatM. peninsulae is predominantly a nocturnal spawner and that spawning coincides with interruptions in current velocities.  相似文献   

9.
Young-of-the-year spot,Leiostomus xanthurus, were sampled in Town Creek of North Inlet Estuary, South Carolina, with towed plankton nets, seines, and stationary block nets from February 14 to May 2, 1981. Age estimates obtained by analysis of daily growth increments in the sagittal otoliths showed that these fish hatched between late November 1980 and mid-February 1981. The youngest spot was estimated to be 60 days old, indicating a prolonged migration period from offshore spawning grounds. Age-length regressions permitted calculations of growth and estimates of age from standard length measurements. An increase in growth rate was observed with an increase in size of fish; however, growth of fish of equal sizes was lower in April and early May than in February and March. Age estimates suggested that the hatching period for young-of-the-year spot was concentrated between late November and mid-January. Recruitment of three separate cohorts into Town Creek occurred at approximately monthly intervals, and immigration of each cohort into the estuary took place approximately 2 months after its estimated date-of-hatch.  相似文献   

10.
Cap-Tourmente tidal flat is located on the north shore of the St. Lawrence middle estuary, 50 km downstream from Quebec city, Canada. Seasonal variations in sedient accretion were studied during the period without ice from May to December, using horizontal plates in conjunction with vertical stakes. The sedimentological regime which is characterized by very rapid changes, can be divided into four periods. There are two periods of intense erosion in May and October–November; during these months, erosion is initiated by walking and beak probing of very large flocks of snow geese. During the summer, very rapid accretion occurs for approximately 100 days; during this period, the sedimentation rate is 2 mm per day in the lower section of the tidal marsh which is covered with vegetation. Among the numerous factors influencing the sedimentation cycle, the very gradual slope of the upper part of the flat (0.25%) seems to be one of the most important because it results in a very large area (550 m wide) which is protected from strong tidal currents. This latter area is covered with dense and high vegetation which provides an effective protection against erosion unitl the snow geese arrive in October and raze it in a few days. The presence of vegetation reduces the velocities of tidal currents, particularly during ebb and modifies their direction for both flood and ebb, orienting them perpendicularly to the main tidal flow.  相似文献   

11.
The spawning activity of the bay scallop Argopecten irradians irradians (Lamarck) was monitored from May through September in a small embayment on Cape Cod, Massachusetts and compared with changes in hydrographic conditions. Spawning activity of bay scallops began in May and continued through July with some minor activity occurring during August and September. Activity was most closely related to changes in ambient temperature and occurred predominantly before the summer maximum temperature was recorded. As temperatures declined in the late summer and early fall, increased gametogenic activity was evident. A longer period of spawning activity was observed than was previously reported for New England waters.  相似文献   

12.
Progress is reported in relating upstream water management and freshwater flow to Florida Bay to a valuable commercial fishery for pink shrimp (Farfantepenaeus duorarum), which has major nursery grounds in Florida Bay. Changes in freshwater inflow are expected to affect salinity patterns in the bay, so the effect of salinity and temperature on the growth, survival, and subsequent recruitment and harvest of this ecologically and economically important species was examined with laboratory experiments and a simulation model. Experiments were conducted to determine the response of juvenile growth and survival to temperature (15°C to 33°C) and salinity (2‰ to 55‰), and results were used to refine an existing model. Results of these experiments indicated that juvenile pink shrimp have a broad salinity tolerance range at their optimal temperature, but the salinity tolerance range narrows with distance from the optimal temperature range, 20–30°C. Acclimation improved survival at extreme high salinity (55‰), but not at extremely low salinity (i.e., 5‰, 10‰). Growth rate increases with temperature until tolerance is exceeded beyond about 35°C. Growth is optimal in the mid-range of salinity (30‰) and decreases as salinity increases or decreases. Potential recruitment and harvests from regions of Florida bay were simulated based on local observed daily temperature and salinity. The simulations predict that potential harvests might differ among years, seasons, and regions of the bay solely on the basis of observed temperature and salinity. Regional differences in other characteristics, such as seagrass cover and tidal transport, may magnify regional differences in potential harvests. The model predicts higher catch rates in the September–December fishery, originating from the April and July settlement cohorts, than in the January–June fishery, originating from the October and January settlement cohorts. The observed density of juveniles in western Florida Bay during the same years simulated by the model was greater in the fall than the spring, supporting modeling results. The observed catch rate in the fishery, a rough index of abundance, was higher in the January–June fishery than the July–December fishery in most of the biological years from 1989–1990 through 1997–1998, contrary to modeling results and observed juvenile density in western Florida Bay.  相似文献   

13.
Sampling in the upper tidal Delaware River between Trenton, New Jersey, and Philadelphia, Pennsylvania, from July 1981 through December 1984 demonstrated the existence of a significant population of shortnose sturgeon. The sturgeon aggregate in the river channel during daylight hours, especially in the area between Trenton and Florence, New Jersey (river km 211.8 to 198.8). Occurrence in the river downstream of Florence appears to be restricted by poor water quality during summer months. Sturgeon were present in the study area throughout the year, but largest numbers were collected from May though November. No spawning was observed during this study, but presence of males with milt suggests that spawning possibly occurs in the Trenton area. Preliminary population estimates (Peterson, Schnabel and Seber-Jolly) indicate an adult population of approximately 6,000–14,000 shortnose sturgeon occupying the upper tidal Delaware River.  相似文献   

14.
Understanding the conditions that drive variation in recruitment of key estuarine species can be important for effective conservation and management of their populations. The Olympia oyster (Ostrea lurida) is native to the Pacific coast of North America and has been a target of conservation efforts, though relatively little information on larval recruitment exists across much of its range. This study examined the recruitment of Olympia oysters at biweekly to monthly intervals at four sites in northern San Francisco Bay from 2010 to 2015 (except 2013). Mean monthly temperatures warmed at all sites during the study, while winter (January–April) mean monthly salinity decreased significantly during a wet year (2011), but otherwise remained high as a result of a drought. A recurring peak in oyster recruitment was identified in mid-estuary, in conditions corresponding to a salinity range of 25–30 and >16 °C at the time of settlement (April–November). Higher average salinities and temperatures were positively correlated with greater peak recruitment. Interannual variation in the timing of favorable conditions for recruitment at each site appears to explain geographic and temporal variation in recruitment onset. Higher winter/spring salinities and warmer temperatures at the time of recruitment corresponded with earlier recruitment onset within individual sites. Across all sites, higher winter/spring salinities were also correlated with earlier onset and earlier peak recruitment. Lower winter salinities during 2011 also resulted in a downstream shift in the location of peak recruitment.  相似文献   

15.
Fish abundance and environmental data collected over ten years (1980–1989) from the middle Thames estuary, England, were analyzed to detect temporal trends in fish populations and relationship with environmental parameters, and to assess water quality. Fish were collected from the cooling water intake screens of West Thurrock power station, situated 35.5 km below London Bridge, in the mid-estuary. Marine species abundance were highly seasonal, with peaks in December–March for herring (Clupea harengus), sprat (Sprattus sprattus), 3-spined-stickleback (Gasterosteus aculeatus), and poor cod (Trisopterus minutus); July–August for flounder (Platichthys flesus); and September–December for sand goby (Pomatoschistus minutus), whiting (Merlangius merlangus), bass (Dicentrarchus labrax), plaice (Pleuronectes platessa), and dab (Limanda limanda). Bimodal seasonal patterns of peaks or unclear seasonality in abundance characterized marine estuarine-dependent sole (Solea solea), Nilsson's pipefish (Syngnathus rostelattus) (April/May and September/October), and pouting (Trisopterus luscus) (May and November/December); the estuarine smelt (Osmerus eperlanus) (October and January) and the catadromous eel (Anguilla anguilla) (June and October). There was substantial variation in the abundance of common species over the period of ten years, with herring, sand goby, flounder, and plaice showing a stable abundance in 1980–1984, increasing sharply in 1985–1986, and then decreasing successively through the remainder of the decade (1987–1989). The first half of the decade was a period of higher abundance for less tolerant species such as smelt, sprat, and poor cod, while the second half showed higher abundances of species tolerant to harsh environmental conditions such as sand goby, flounder, eel, and plaice. A general pattern of stable fish populations with a slight trend of deterioration was found to emerge over the years, related to the number of species and quantities of common species. Multivariate techniques of principal component and canonical correspondence ordinations were used for assessing relationships between fish populations abundance and environmental variables. The most significant environmental variables correlated with fish species were temperature and dissolved oxygen. High abundances of flounder were associated with high temperature, while high abundance of poor cod, sprat, herring, and 3-spined-stickleback were associated with high dissolved oxygen, flow, ammonical nitrogen, and low temperature. Plaice, whiting, sand goby, bass, and dab were preferentially found in high salinity and suspended solids, while smelt and sole were likely to prefer average values or showed no clear preferences.  相似文献   

16.
Ribbed mussels (Geukensia demissa) help form the basis of highly productive salt marshes along the Atlantic coast of North America, in southern New England, and further south. Little is known about their ecology and reproductive biology at more northern latitudes (Maritime Canada; >43o N). As a step in determining the sustainability of ribbed mussel populations near the northern limit of their range (Northumberland Strait, Gulf of St. Lawrence, Canada), gametogenesis and spawning were monitored over 3 years (May–August 2012, June–November 2014, and April–October 2015) at four sites spanning ~100 km of coastline. These sites are typically ice-covered from mid-December to March or April. The onset of gametogenesis was later, the reproductive stages on any given date were more varied, and the reproductive season was shorter than for southern populations of ribbed mussels. Oocyte density and size did not vary among sites, indicating similar site-level processes, but did vary among years. Oocyte density and size varied greatly among mussels at a given site, and within a single gonad. This highlights the importance of individual variability, perhaps related to mussel location within a marsh, and the effects of nutrients and temperature on gonads. Accounting for the individual-level variability, reproductive output was estimated at ~105 oocytes per ripe female mussel, which is within the fecundity estimates for other marine bivalve broadcast spawners.  相似文献   

17.
The northern pipefish,Syngnathus fuscus, is an abundant component of estuarine faunas along the east coast of the United States, yet little is known of its life history. Northern pipefish were collected from several areas in southern New Jersey, particularly the Great Bay-Little Egg Harbor estuarine system, to determine aspects of its reproduction and to estimate its age and growth. A monthly gonadosomatic index for both males and females indicated a spring through summer spawning period, with a peak in reproductive activity during June. A male brood pouch-somatic index indicated a prolonged male brooding period over spring through summer, with a peak in June. The size of males with broods ranged from 119–222 mm total length (TL), and the number of eggs within a brood varied from 45 to 1380. Individual embryos within a brood were identical in development stage, suggesting each brood resulted from a single mating. Young-of-the-year occurred in samples from May through November, with peak abundance in June. Individuals in this year class were extremely variable in size by the end of the first growing season, varying from 5 mm TL to 200 mm TL in November. At approximately 1 yr of age, individuals were 70–220 mm TL and many were of sufficient size to reproduce, indicating that the events of the first year of life for this species are of central importance to an understanding of its population dynamics.  相似文献   

18.
The distribution, hatching dates, growth, and food habits of larval and juvenile red drum (Sciaenops ocellatus) in Tampa Bay, Florida, are described. From September 1981 through November 1983, 800 larvae and 7,536 juveniles (98%<100 mm SL) were collected, primarily with plankton nets and bag seines. Analysis of otoliths and length-frequency distributions indicate that spawning took place from mid-August through late November with a major peak during October in 1981 and 1982. Larvae became less abundant, but increased in size, from the mouth to the upper bay, indicating that spawning took place in the bay mouth or nearshore waters. At about 8 mm SL (17 days old) larvae settled out along the bay shore before migrating toward low salinity backwater areas. Juveniles grew to about 55 mm SL by the end of December and 303 mm SL by the end of their first year. Young red drum gradually moved back into the bay with increased size and age. Eighty-five percent of larval stomachs, examined were empty; those with food contained copepods almost exclusively. Fewer than 7% of juvenile stomachs were empty. Small juveniles fed primarily on mysids, amphipods, and shrimp, whereas larger juveniles fed more on crabs and fish. Changes in diet were noted with growth, but few differences were seen among areas or habitat types.  相似文献   

19.
Aerial surveys were conducted in the lower Chesapeake Bay during 1986–1989 to estimate abundance and examine the distribution of the cownose ray,Rhinoptera bonasus, during its seasonal residence, May–October. Most of the survey effort was concentrated in the lower and mid-bay regions. Cownose rays appeared uniformly distributed across the bay during mid-summer, but were more abundant in the eastern portion of the bay during migration. North-south distribution varied and reflected the general seasonal migration pattern. Mean abundance increased stepwise monthly from June through September and declined dramatically in October with their emigration from the bay. Abundance estimates from individual surveys varied. The greatest range of individual survey abundance estimates occurred in September (0–3.7×107 cownose rays0 due to high variation in school size and abundance between surveys. Monthly mean cownose ray abundance ranged from 0 in May and November to an estimated maximum of 9.3×106 individuals in September. The magnitude of the population suggests that the cownose ray plays an important role in the trophic dynamics of the Chesapeake Bay ecosystem. The historical data were insufficient to determine whether the population has increased, but these surveys provided the baseline data which would allow future investigation of cownose ray population dynamics in lower Chesapeake Bay.  相似文献   

20.
Estuarine nursery areas are critical for successful recruitment of tautog (Tautoga onitis), yet they have not been studied over most of this species' range. Distribution, abundance and habitat characteristics of young-of-the-year (YOY, age 0) and age 1+juvenile tautog were evaluated during 1988–1992 in the Narragansett Bay estuary, Rhode Island, using a 16-station, beach-seine survey. Estuary-wide abundance was similar among years. Greatest numbers of juveniles were collected at northern Narragansett Bay stations between July and September. Juvenile abundances varied with density of macroalgal and eelgrass cover; abundances ranged from 0.03 fish per 100 m2 to 8.1 fish per 100 m2. Although juveniles use eelgrass, macroalgae is the dominant vegetative cover in Narragansett Bay. Macroalgal habitats play a previously unrealized, important role and contribute to successful recruitment of juvenile tautog in Narragansett Bay. Juvenile abundances did not vary with sediment type or salinity, but were correlated with surface water temperature. Fish collected in June were age 1+ juveniles from the previous year-class (50–167 mm TL) and these declined in number after July or August. The appearance of YOY (25–30 mm TL) in July and August was coincident with the period of their greatest abundances. A precipitous decline in abundance occurred by October because of the individual or combined effects of mortality and movement to alternative habitats. Based on juvenile abundance, a previously unidentified spawning area was noted in Mount Hope Bay, a smaller embayment attached to the northeastern portion of Narragansett Bay. In August 1991, Hurricane Bob disrupted juvenile sise distribution and abundance, resulting in reduced numbers of YOY collected after the storm and few 1+ juveniles in 1992.  相似文献   

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