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1.
In this study we used pinfish (Lagodon rhomboides) in field experiments to examine linkages between intertidal saltmarsh and adjacent subtidal habitats. Pinfish are more than twice as abundant in intertidal marshes adjacent to seagrass beds than in those adjacent to the unvegetated subtidal bottom. Movement of pinfish between the marsh edge and the adjacent subtidal habitat was greater for fish captured in areas with both intertidal and subtidal vegetation than in those with intertidal vegetation and adjacent unvegetated mudflats. This movement provides an important link between habitats, allowing transfer of marsh-derived secondary production to subtidal seagrass beds and vice versa. Pinfish held in enclosures with both intertidal and subtidal vegetation were, on average, approximately 90% heavier than fish held in enclosures with intertidal vegetation and unvegetated subtidal bottom. Because saltmarshes and seagrass beds contribute to the production of living marine resources, active measures are being taken to preserve and restore these habitats. The results from this study have direct application to decisions concerning site selection and optimal spatial proximity of saltmarsh and seagrass habitats in the planning of restoration and mitigation projects. To maximize secondary production and utilization of intertidal marshes, managers may opt to restore and/or preserve marshes adjacent to subtidal seagrass beds. Received: 31 May 1996 / Accepted: 23 October 1996  相似文献   

2.
Intertidal movements of fish larvae and juveniles on a mudflat in the Tama River estuary, central Japan, were investigated by comparing the abundance and sizes of fishes caught in the intertidal zone during flood tides with those in the subtidal zone during low tides. A total of 28465 individuals, belonging to 9 families and 20 species, were collected by small purse seine. Among the abundant species, planktonic larvae and juveniles of gobiids and Konosirus punctatus were more abundant in the intertidal zone at flood tide than the subtidal zone at low tide. Similar occurrence patterns were found in juvenile Plecoglossus altivelis altivelis and Lateolabrax japonicus, having fully developed swimming abilities. In contrast to these species, much higher abundances of epibenthic juveniles of 2 gobiids (Acanthogobius flavimanus and Gymnogobius macrognathos) were found in the subtidal zone at low tide, although they also utilized the intertidal zone at flood tide.  相似文献   

3.
The effects of a macroalgal mat (Ulva lactuca) on intertidal sand flat copepods were studied in Jamaica Bay, NY. In 1999, Ulva was removed from paired quadrats in the algal mat. Density and species richness were estimated from sediment cores over seven biweekly periods and compared with Ulva-removal quadrats and with an unvegetated reference site. In a separate analysis at the same site, species composition and density of all copepods within the algal mat were determined from replicated quadrat samples over seven dates. Emergence traps were deployed in all treatments in 1999 to quantify copepod movements from sediments into the water column during flooding tide. Dissolved oxygen (DO) was continuously monitored over several 96-h periods in and above the algal mat. In 2000, three biomass levels of Ulva (0, 100, 200 g DW per m2) were added to paired quadrats in the unvegetated zone. Density and species richness were estimated over eight time periods. Ulva removal resulted in significant increases in density and species richness, but levels remained lower than at the unvegetated site. Likewise, addition of Ulva biomass produced significant declines in copepod density. However, the differences between low- and high-Ulva-addition treatments were insignificant. Increases in phytal copepods after Ulva addition did not compensate for losses of epibenthic and infaunal species. The overall effect of the Ulva mat was a net loss of copepod density, including the loss of nearly all infaunal species. Anoxia in sediments and within the algal mat are correlated with declines in infaunal species and with escape by some infaunal species from the sediment into the water column.  相似文献   

4.
We conducted a series of experiments to determine the movements and fidelity of juvenile pinfish, Lagodon rhomboides, in salt marsh creeks within North Inlet Estuary, SC. In Experiment 1, we investigated the fidelity of pinfish (40–100mm SL) at four subtidal locations (9–617m apart) along the axis of a major creek. We trapped and marked 2,297 individuals and recaptured 15–22% of the fishes released at each site, almost all of which (99.7%) had been marked at the same location of recapture up to 3 months earlier. In Experiment 2, we investigated pinfish movements between subtidal and intertidal areas. In the 8 weeks prior to sampling 2 intertidal creeks, we marked 950 juveniles in the adjacent subtidal areas. Sampling of the 2 flooded intertidal creeks showed that 9–20% of the pinfish collected bore marks, and all had been previously marked at the subtidal site immediately adjacent to the intertidal creek. Gut analysis of 60 individuals revealed that juveniles collected from the intertidal areas at high tide had consumed about ten times more food than those collected at the subtidal sites at low tide. In Experiment 3, we determined the fidelity of recently settled pinfish (<35mm SL) and showed that 15% of the 434 marked pinfish remained in the same area; some were at liberty up to 7 weeks. In Experiment 4, we determined home range by tagging and recapturing juvenile pinfish at sites separated by 20m along a 200m subtidal transect. We estimated that during periods when the intertidal zone was not accessible, the average home range was 9.4m with only 10% of tagged fish moving greater than 20m during the 4 month study. Our results indicate that soon after recruitment to the estuary, pinfish establish strong fidelity for sites within salt marsh creeks and exhibit tidal periodicity in both movements and feeding.  相似文献   

5.
Summary We conducted a series of field experiments to examine the roles of refuge and food availability in explaining the distribution and abundance of fish in tidal freshwater marsh creeks. Two hypotheses were tested: (1) relative predation pressure is less in SAV than in unvegetated areas and (2) fish food availability is greater in SAV than in nearby unvegetated areas. Tethering experiments using mummichogs (Fundulus heteroclitus) in vegetated and unvegetated areas revealed that relative predation pressure was significantly less in areas with SAV. Banded killifish (Fundulus diaphanus) maintained in vegetated enclosures consumed prey associated with SAV, whereas those held in unvegetated pens had empty stomachs. No differences were found in the number of prey eaten by bluespotted sunfish (Enneacanthus gloriosus) or mummichogs when confined in vegetated or unvegetated enclosures. However, larger prey were consumed by bluespotted sunfish and mummichogs maintained in vegetated enclosures. These data suggest that foraging profitability is significantly enhanced by feeding in the SAV. Submerged plant beds in tidal freshwater marsh creeks not only afford protection from predators, but also provide a rich foraging habitat. By foraging in SAV, fish consume larger prey and may have higher growth rates, lower mortality, and higher fecundity.  相似文献   

6.
Three common vegetation types were studied to assess habitat partitioning in juvenile fishes in select warm temperate estuaries of South Africa. Vegetated habitat types are known as productive and important areas for predator avoidance and feeding and are often preferred by juvenile fishes. Habitat partitioning is not well understood, with previous studies mostly focusing on seagrass (Zostera capensis). This study aimed to assess three common vegetated fish nursery areas in estuaries to aid conservation planning. Fishes were collected by means of double-winged, six-hooped fyke nets, 1 mm mesh size secured in placed on the nocturnal flood tide at each inundated vegetation type (Phragmites australis, Zostera capensis, Spartina maritima) and at an adjacent unvegetated site for three consecutive months in 2014 and 2015 during the summer recruitment period for juvenile fishes. Higher catches were frequently recorded in vegetated areas for solely estuarine and marine estuarine dependent species. In general, the previously unstudied reed, P. australis showed the highest species richness and abundance of juvenile fishes overall, followed by, Z. capensis and the intertidal salt marsh species, S. maritima. Results from this study supports international trends on the value of vegetated areas as refugia for young fishes in estuaries.  相似文献   

7.
In this note we report on changes of activity level of littoral fish and their use of different microhabitats in an altered intertidal environment, where intertidal fish are never emersed and turbulence is confined to high tides. Despite these atypical conditions, the structure of the assemblage is basically the same found in a typical rocky-shore situation. Two intertidal fish known to possess internal tidal rhythms, Lipophrys pholis and Coryphoblennius galerita, retain those rhythms in these altered conditions, and the associated social changes in L. pholis are also retained. These observations support the studies of Gibson (1971), who showed that changes in hydrostatic pressure were of prime importance in keeping the tidal rhythm entrained. The subtidal Parablennius pilicornis, on the contrary, is more active during low tide than at high tide. The hypothesis that some subtidal species are excluded from the intertidal by a turbulence-avoiding mechanism is discussed.  相似文献   

8.
We conducted a survey to provide knowledge on mechanisms controlling spatial and temporal variability of macrobenthos in an intertidal Wadden Sea area partly covered by invasive Spartina anglica. Benthic macrofauna was collected seasonally at seven stations along a transect covering non-vegetated mudflat and vegetated marsh areas. Shannon diversity index was consistently higher for macrobenthos in the open mudflat compared to the marsh area. Infaunal species, like Arenicola marina, Tubificoides benedeni and Macoma balthica, were more abundant in the mudflat than the marsh, while the opposite was evident for epifaunal species, like Hydrobia ulvae and Littorina littorea. The infaunal crustacean, Corophium volutator, on the other hand, appeared particularly attracted to the mudflat–marsh boundary. The biomass of below-ground plant materials and macrodetritus was positively correlated with the total macrofaunal abundance, while the biomass of dead below-ground plant materials alone showed a significant negative correlation with infaunal abundance. Total macrofaunal abundance was highest during summer in the mudflat, while no seasonal pattern was evident in the marsh. The negative influence of S. anglica invasions on infaunal abundance may have serious implications for higher trophic levels, such as waterbirds, that forage in Wadden Sea areas and thus for the overall biodiversity and ecosystem functioning.  相似文献   

9.
Functional responses of estuarine fish species to environmental perturbations such as wetland impoundment, changes in water quality, and sediment accretion are investigated. The study focuses on the feeding, growth and habitat use by California killifish (Fundulus parvipinnis), topsmelt (Antherinops affinis), and juvenile California halibut (Paralichthys californicus) in impacted coastal wetlands to provide an ecological basis for guidance on the management and restoration of these ecosystems. The ecology of California killifish, Fundulus parvipinnis, is closely tied with the marsh surface, which they access at high tide to feed and grow. Field estimates of food consumption show that killifish can increase their food intake by two-fold to five-fold by adding marsh surface foods to their diet. Bioenergetics modeling predicts that killifish can grow over an order of magnitude faster if they add intertidal marsh surfaces to their subtidal feeding areas. Tidal inlet closures and increased marsh surface elevations due to sediment accretion can restrict killifish access to the marsh surface, affecting its growth and fitness. An open tidal inlet and tidal creek networks that allow killifish to access the marsh at high tide must be incorporated into the restoration design. Topsmelt and California halibut are also adversely affected by tidal inlet closures. Food consumption rates of topsmelt are 50% lower when the tidal inlet is closed, compared to when the estuary is tidally-flushed. Tidal inlet closures inadvertently induce variations in water temperature and salinity and negatively affect growth of juvenile California halibut. Tidal creek networks which consist of channels and creeks of various orders are also important to halibut. Large halibut (>200 mm TL) inhabit deeper, high order channels for thermal refuge, while small halibut (<120 mm TL) are abundant in lower order channels where they can feed on small-sized prey which are typically less abundant in high order channels. Maintaining an open tidal inlet, implementing sediment management programs and designing coastal wetlands with tidal creek networks adjacent to intertidal salt marsh habitat (for fish access) are key elements that need to be considered during the planning and implementation of coastal wetland restoration projects.  相似文献   

10.
Nekton was sampled in five marshes along the salinity gradient of the Schelde River. The utilisation of three different habitats (large and small creek, marsh pond) by fish and macrocrustacean species was compared among the five sampling sites. In the larger channels fyke nets were deployed to capture fish and macrocrustaceans leaving the marsh at ebb while block nets were set in smaller intertidal creeks. Fish traps passively sampled fish and shrimp in the marsh ponds. The tidal freshwater marsh had a species poor fauna and only a low number of fish was caught. Besides some freshwater species (Alburnoides bipunctatus, Carassius carassius) the European eel, Anguilla anguilla was still present. The four other marshes had a similar community structure although Platichthys flesus was absent from the euhaline area. Among fish species, dominance of Dicentrarchus labrax, Platichthys flesus and Pomatoschistus microps was observed. Carcinus maenas and Palaemonetes varians were the most abundant macrocrustacean species in every marsh. Between the large and small intertidal creeks there was no difference in nekton species composition. The main species used both habitats. Marsh ponds were utilized intensively only by two species, Pomatoschistus microps and Palaemonetes varians in every marsh.  相似文献   

11.
The present study focuses on the spatial and temporal distribution of the macroinvertebrate community of the salt marsh areas of the Tejo estuary, based on surveys conducted from autumn 1998 to summer 2000. Samples were collected quarterly in five different intertidal areas along an elevation gradient in: mudflats, creek mouths, creeks, pioneer salt marsh areas and middle marsh areas. A total of 36 benthic invertebrate taxa were identified. Insect larvae were the most well represented group, with 10 taxa identified. Oligochaetes and ostracods were the most numerically abundant taxa, whereas bivalves dominated in biomass. Benthic macroinvertebrate assemblages were dominated, both in number and biomass, by deposit feeders. Three distinct macroinvertebrate assemblages were distinguished along the elevation gradient, based on species presence, density and biomass: the unvegetated muddy areas with a macrobenthic assemblage composed mostly by infauna; the salt marsh pioneer areas of Spartina maritima in which several epibenthic taxa were found, as well as endobenthic taxa characteristic of muddy sediment; and the creek margins, with epifauna taxa such as insect larvae and crustaceans and a low abundance of benthic infauna. Total biomass in the unvegetated and Spartina areas was higher during spring and summer mainly due to the increase in biomass of Scrobicularia plana and Hydrobia ulvae. No decreases in the salt marsh macroinvertebrate biomass values were observed during the highest densities of their potential nektonic predators (summer). This fact might indicate that macroinvertebrates are not a limiting resource for the nektonic species, and that the natural biomass increment of these invertebrate species could be masking the predation/disturbance caused by the nektonic species.  相似文献   

12.
Flux calculations demonstrate that many estuaries are natural filters for trace metals. Yet, the underlying processes are poorly investigated. In the present study, it was hypothesized that intertidal marshes contribute significantly to the contaminant filter function of estuaries. Trace metal concentrations and sediment characteristics were measured along a transect from the subtidal, over an intertidal flat and marsh to a restored marsh with controlled reduced tide. Metal concentrations in the intertidal and restored marsh were found to be a factor two to five higher than values in the subtidal and intertidal flat sediments. High metal concentrations and high accretion rates indicate a high metal accumulation capacity of the intertidal marshes. Overbank sedimentation in the tidal marshes of the entire estuary was calculated to remove 25% to 50% of the riverine metal influx, even though marshes comprise less than 8% of the total surface of the estuary. In addition, the large-scale implementation of planned tidal marsh restoration projects was estimated to almost double the trace metal storage capacity of the present natural tidal marshes in the estuary.  相似文献   

13.
The intertidal and subtidal soft bottom macro- and meiofauna of a glacier fjord on Spitsbergen was studied after complete ice melt in June 2003. The abundances of the benthic fauna were within the range reported from estuaries and similar intertidal areas of boreal regions. The high proportion of juveniles in the eulittoral zone indicated larval recruitment from subtidal areas. The macrobenthic fauna can be divided into an intertidal and a subtidal community, both being numerically dominated by annelids. Deposit feeders were numerically predominant in intertidal sites, whereas suspension feeders were most abundant in the subtidal area. Among the meiofauna, only the benthic copepods were identified to species, revealing ecological adaptations typical for intertidal species elsewhere.  相似文献   

14.
Green BC  Smith DJ  Grey J  Underwood GJ 《Oecologia》2012,168(1):245-255
Adult and juvenile fish utilise salt marshes for food and shelter at high tide, moving into adjacent sublittoral regions during low tide. Understanding whether there are high levels of site fidelity for different species of coastal fish has important implications for habitat conservation and the design of marine protected areas. We hypothesised that common salt marsh fish species would demonstrate a high site fidelity, resulting in minimal inter-marsh connectivity. Carbon (13C) and nitrogen (15N) stable isotope ratios of larvae and juveniles of five common salt marsh fish (Atherina presbyter, Chelon labrosus, Clupea harengus, Dicentrarchus labrax, Pomatoschistus microps), seven types of primary producer and seven secondary consumer food sources were sampled in five salt marshes within two estuary complexes along the coast of south-east England. Significant differences in 13C and 15N signatures between salt marshes indicated distinct sub-populations utilising the area of estuary around each salt marsh, and limited connectivity, even within the same estuary complex. 15N ratios were responsible for the majority of inter-marsh differences for each species and showed similar site-specific patterns in ratios in primary producers, secondary consumers and fish. Fish diets (derived from isotope mixing models) varied between species but were mostly consistent between marsh sites, indicating that dietary shifts were not the source of variability of the inter-marsh isotopic signatures within species. These results demonstrate that for some common coastal fish species, high levels of site fidelity result in individual salt marshes operating as discrete habitats for fish assemblages.  相似文献   

15.
Spartina anglica is an exotic perennial grass that can rapidly colonise the intertidal zone of temperate estuaries and lagoons. Consequently, there is considerable concern about its impact on estuarine flora and fauna. This study provides the first investigation of ecological impacts by S. anglica in Australia. The objective was to investigate the impacts of S. anglica on benthic macroinvertebrate communities inhabiting mudflat and native saltmarsh habitats at Little Swanport estuary, Tasmania. The null hypothesis that species richness and species abundance of benthic macroinvertebrates in exotic S. anglica marsh does not differ from adjacent native saltmarsh and mudflat habitats was tested. Eighteen species and 3716 macroinvertebrates were collected from 60 intertidal core samples in three habitats. Species richness, total abundance of invertebrates, crustacean abundance and mollusc abundance of mudflat communities were significantly (P < 0.05) lower when compared to those inhabiting adjacent S. anglica marsh and native saltmarsh. However, species richness and total abundance of invertebrates of native saltmarsh and S. anglica marsh did not differ significantly. Ordination of macroinvertebrate data clearly separated mudflat sites from vegetated sites but showed remarkable similarity between exotic and native vegetated sites.  相似文献   

16.
We characterized demersal fish and decapod crustacean habitats in 14 shallow (< 12m) areas in Penobscot Bay, Maine, by mapping the distribution of subtidal substrata with an acoustic sea bottom profiler. We identified the aquatic vegetation and the fishes and decapods associated with these habitats. Samples of fishes and decapods in each habitat were collected with a small beam trawl. The seabed at most of the stations sampled was composed of a mosaic of substrata. More species of fishes tow-1 and higher abundances of fishes and decapods were found in stations with vegetation present, particularly eelgrass, Zostera marina. Decapod species richness tow-1 was similar between vegetated and unvegetated habitats. Shallow habitats in Penobscot Bay were dominated by juvenile fishes and function as nursery areas. The greater species diversity and higher abundances of epibenthic fishes and decapod crustaceans observed in vegetated habitats, particularly beds of Zostera marina, compared with unvegetated areas in Penobscot Bay conform to the hypothesis that increased habitat complexity results in increased species richness and abundance.The first author is also senior author  相似文献   

17.
Near the East Frisian island of Norderney two sites are investigated permanently in order to study long-term fluctuations of macrozoobenthos: one transect (since 1977) at the northern side in shallow subtidal waters and another one (since 1976) at the sheltered southern side in the intertidal area of the Wadden Sea. Since 1980 the investigations have been continued in the frame of COST-47, sedimentary intertidal programme (including the shallow subtidal habitats colonized by the Macoma balthica community).The results up to 1984, respectively to 1985, are presented and the changes of abundance of the dominant species are discussed. Discussed are also the influences of water temperatures and sediment disturbances caused by wave action. There is evidence that the intertidal variety of the Macoma balthica community shows a greater stability than the subtidal variety.  相似文献   

18.
This study was undertaken to determine the rates and controls ofanaerobic respiration reactions coupled to organic matter mineralization as afunction of space and time along a transect from a bioturbated creekbank to themidmarsh in Georgia saltmarsh sediments. Sulfate reduction rates (SRR) weremeasured at 3 sites during 5 sampling periods throughout the growth season. Thesites differed according to hydrologic regime and the abundance of dominantplants and macrofauna. SRR and pore water / solid phase geochemistry showedevidence of enhanced sediment oxidation at sites exposed to intensebioturbation. Iron(III) reduction rates (FeRR) were directly determined insaltmarsh sediments for the first time, and in agreement with measured SRR,higher rates were observed at the bioturbated, unvegetated creekbank (BUC) andbioturbated, vegetated levee (BVL) sites in comparison to a vegetated mid-marsh(MM) site. An unexpected result was the fact that SRR varied nearly as muchbetween sites (2–3 x) as it did with temperature or season (3–4 x).The BVL site, vegetated by the tall form of Spartinaalterniflora, always exhibited the highest SRR and carbon oxidationrates (> 4000 nmol cm–3 d–1) with high activity levels extending deep ( 50 cm)into the sediment, while the MM site, dominated by the short form ofSpartina, always exhibited the lowest SRR which werelocalized to the top 15 cm of sediment. SRR and FeRR at BUC wereintermediate between those measured at the BVL and MM. Acetate was the mostabundant microbial fermentation product (concentrations up to > 1mM) in marsh porewaters, and its distribution reflectedrespirationactivity. Chemical exchange, caused by bioturbation, appeared to be the primarycontrol explaining trends in rates of sulfate and Fe(III) reduction withmacrophytes and carbon source acting as secondary controls.  相似文献   

19.
Larval and juvenile fishes were collected at low tide from the surface of an intertidal salt marsh on Sapelo Island, Georgia every 6 days from 25 May through 20 December 1982. Larval fishes were present in shallow puddles of tidal water on the marsh from the beginning of the sampling period until the end of October. Juveniles were present throughout the year. Fundulus heteroclitus (Linnaeus) and F. luciae (Baird) accounted for 96.3% (67.0% and 29.3%, respectively) of the 4355 fishes collected. These fishes exhibited synchronous, temporal pulses in larval abundance, suggesting that reproduction was discontinuous and controlled by the same factor(s) in both species. Larval F. heteroclitus inhabited aquatic micro-habitats near the upland edge of the intertidal marsh, but as the larvae grew to juvenile size (≈ 10 mm standard length) they moved to lower elevations near a tidal creek. Large juveniles and adults of F. heteroclitus infrequently occurred in the samples, presumably because they leave the intertidal marsh as the tide ebbs. F. luciae were rarely found in low marsh areas, but all age classes (including adults) occurred at higher elevations, supporting previous suggestions that this species prefers high marsh habitats. The vegetated, intertidal salt marsh appears to be the principal nursery habitat for both of these cyprinodontid species.  相似文献   

20.

Coastal wetlands are key in regulating coastal carbon and nitrogen dynamics and contribute significantly to climate change mitigation and anthropogenic nutrient reduction. We investigated organic carbon (OC) and total nitrogen (TN) stocks and burial rates at four adjacent vegetated coastal habitats across the seascape elevation gradient of Cádiz Bay (South Spain), including one species of salt marsh, two of seagrasses, and a macroalgae. OC and TN stocks in the upper 1 m sediment layer were higher at the subtidal seagrass Cymodocea nodosa (72.3 Mg OC ha−1, 8.6 Mg TN ha−1) followed by the upper intertidal salt marsh Sporobolus maritimus (66.5 Mg OC ha−1, 5.9 Mg TN ha−1), the subtidal rhizophytic macroalgae Caulerpa prolifera (62.2 Mg OC ha−1, 7.2 Mg TN ha−1), and the lower intertidal seagrass Zostera noltei (52.8 Mg OC ha−1, 5.2 Mg TN ha−1). The sedimentation rates increased from lower to higher elevation, from the intertidal salt marsh (0.24 g cm−2 y−1) to the subtidal macroalgae (0.12 g cm−2 y−1). The organic carbon burial rate was highest at the intertidal salt marsh (91 ± 31 g OC m−2 y−1), followed by the intertidal seagrass, (44 ± 15 g OC m−2 y−1), the subtidal seagrass (39 ± 6 g OC m−2 y−1), and the subtidal macroalgae (28 ± 4 g OC m−2 y−1). Total nitrogen burial rates were similar among the three lower vegetation types, ranging from 5 ± 2 to 3 ± 1 g TN m−2 y−1, and peaked at S. maritimus salt marsh with 7 ± 1 g TN m−2 y−1. The contribution of allochthonous sources to the sedimentary organic matter decreased with elevation, from 72% in C. prolifera to 33% at S. maritimus. Our results highlight the need of using habitat-specific OC and TN stocks and burial rates to improve our ability to predict OC and TN sequestration capacity of vegetated coastal habitats at the seascape level. We also demonstrated that the stocks and burial rates in C. prolifera habitats were within the range of well-accepted blue carbon ecosystems such as seagrass meadows and salt marshes.

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