共查询到20条相似文献，搜索用时 46 毫秒
1.
We sampled nekton (fishes and decapod crustaceans) in submerged aquatic vegetation (SAV) (Potanogeton nodosus, Najas guadalupensis), in emergent marsh vegetation (Sagittaria spp. andScirpus americanus), and over unvegetated bottom associated with three islands in the Atchafalaya River Delta, Louisiana. The purpose of our study was to quantify nekton densities in these major aquatic habitat types and to document the relative importance of these areas to numerically dominant aquatic organisms. We collected a total of 33 species of fishes and 7 species of crustaceans in 298 1-m2 throw trap samples taken over three seasons: summer (July and August 1994), fall (September and October 1994), and spring (May and June 1995). Fishes numerically accounted for >65% of the total organisms collected. Vegetated areas generally supported much higher nekton densities than unvegetated sites, although bay anchoviesAnchoa mitchilli were more abundant over unvegetated bottom than in most vegetated habitat types. Among vegetation types, most species showed no apparent preference between SAV and marsh. However, inland silversidesMenidia beryllina and freshwater gobiesGobionellus shufeldti were most abundant inScirpus marsh in summer, and blue crabsCallinectes sapidus were most abundant in SAV (Potamogeton) in spring. Several species (sheepshead minnowCyprinodon variegatus, rainwater killifishLucania parva, and blue crab) apparently selected the vegetated backmarsh of islands (opposite of riverside) over stream-sideScirpus marsh. Freshwater gobies, in contrast, were most abundant in streamsideScirpus marsh. Densities of juvenile blue crabs were high (up to 17 m−2) in vegetated delta habitat types and comparable to values reported from more saline regions of Gulf Coast estuaries. Shallow vegetated habitat types of the Atchafalaya River Delta and other tidal freshwater systems of the Gulf Coast may be important nursery areas for blue crabs and other estuarine species. 相似文献
2.
Alan T. Hitch Kevin M. Purcell Shannon B. Martin Paul L. Klerks Paul L. Leberg 《Estuaries and Coasts》2011,34(3):653-662
Increases in relative sea level are fragmenting the emergent vegetation of Louisiana’s coastal marshes. Nekton abundance is
likely impacted by salinity and whether emergent vegetation is replaced by submerged aquatic vegetation (SAV) or open water.
To assess these effects, we sampled nekton densities along a salinity gradient (categorized as freshwater, intermediate, and
brackish marsh) in fragmented and non-fragmented areas. Total nekton density increased strongly with SAV in brackish marsh
but only weakly in freshwater marsh (F
2,238 = 10.03, p < 0.0001). Freshwater and intermediate marshes had higher nekton densities when fragmented than when non-fragmented; this
relationship was reversed in brackish marsh (F
2,238 = 8.89, p = 0.0002). Fragmentation, SAV, and salinity interacted to affect the densities of Gambusia affinis, Poecilia latipinna, Cyprinodon variegates, and Lucania parva. Our results suggest that the presence of both emergent vegetation and SAV was necessary for maintaining high nekton densities,
with this combination being especially important in brackish marshes. 相似文献
3.
We examined the distribution of nekton across the marsh landscape using a 1-m2 drop sampler to compare nekton densities across three different salinity zones (intermediate, brackish, saline), three pond
sizes (diameter <40 m = small, ∼250–300 m = medium, >750 m = large), and two habitat types (pond, adjacent marsh) in the Barataria
Bay Estuary, Louisiana. Nekton assemblages of ponds and the adjacent marsh appeared to be structured by the responses of individual
species to the estuarine salinity gradient at the landscape scale and to pond habitat attributes locally. Our results indicate
that ponds in the brackish and saline zones are more important nursery areas for most fishery species than ponds in the intermediate
zone. Medium and large ponds supported higher densities of most species than small ponds. Most species of nekton were associated
with vegetation structure, and individuals of these species were either concentrated among plant stems at the marsh edge or
within submerged aquatic vegetation in ponds. 相似文献
4.
Comparison of the relative abundance of fish species from different life-history groups and their temporal patterns of estuarine habitat use from two estuaries north and south of Cape Cod indicates that the Cape acts as a zoogeographic boundary. Between April 1988 and December 1989, monthly seine and trawl samples were collected from nearshore, shallow-water marsh, and beach and deeper open-water habitats in Wells Harbor, Maine, and Waquoit Bay, Massachusetts. Forty-eight species and 80,341 individuals were collected from Waquoit Bay compared to 24 species and 22,561 individuals from Wells Harbor. Waquoit Bay had proportionally fewer resident species and more marine, nursery, and occasional species than Wells Harbor. Annual density and biomass values were greater across all habitats in Waquoit Bay, with the summer values from the marsh habitat an order of magnitude higher than comparable summer data from the Wells habitats. We suggest that marsh and beach habitats provide a nursery area for young-of-the-year fishes, while deeper, open-water habitats serve as a corridor for fishes moving to nearshore habitats or serve as a refuge during low tide. 相似文献
5.
In Grand Bay National Estuarine Research Reserve (Grand Bay NERR), Mississippi, we used quantitative drop sampling in three
common shallow estuarine habitats—low profile oyster reef (oyster), vegetated marsh edge (VME), and nonvegetated bottom (NVB)—to
address the dearth in research comparing nekton utilization of oyster relative to adjacent habitats. The three habitats were
sampled at two distinct marsh complexes within Grand Bay NERR. We collected a total of 633 individual fishes representing
41 taxa in 22 families. The most diverse fish family was Gobiidae (seven species) followed by Blennidae and Poeciliidae (three
species each). We collected a total of 2,734 invertebrates representing 24 taxa in 11 families. The most diverse invertebrate
family was Xanthidae (six species) followed by Palaemonidae (five species). We used ordination techniques to examine variation
in species relative abundance among habitats, seasons, and sampling areas, and to identify environmental gradients correlated
with species relative abundances. Our resulted indicated that oyster provided a similarly complex and important function as
the adjacent VME. We documented three basic trends related to the importance of oyster and VME habitats: 1) Oyster and VME
provide habitat for significantly more species relative to NVB, 2) Oyster and VME provide habitat for rare species, and 3)
Several species collected across multiple habitats occurred at higher abundances in oyster or VME habitat. We also found that
salinity, temperature, and depth were associated with seasonal and spatial shifts in nekton communities. Lastly, we found
that the relative location of the two marsh complexes we studied within the context of the whole estuary may also explain
some of the temporal and spatial differences in communities. We conclude that oyster habitat supported a temporally diverse
and spatially distinct nekton community and deserves further attention in research and estuarine conservation efforts. 相似文献
6.
Fish community ecology in an Altered River delta: Spatial patterns in species composition, life history strategies, and biomass 总被引：1，自引：0，他引：1
Matthew L. Nobriga Frederick Feyrer Randall D. Baxter Michael Chotkowski 《Estuaries and Coasts》2005,28(5):776-785
We sampled nearshore fishes in the Sacramento-San Joaquin Delta, California, United States, during 2001 and 2003 with beach seines and gill nets. We addressed three questions. How and why did fish assemblages vary, and what local habitat features best explained the variation? Did spatial variation in assemblages reflect greater success of particular life history strategies? Did fish biomass vary among years or, across habitats? Nonmetric multidimensional scaling showed that habitat variables had more influence on fish assemblages than temporal variables. Results from both gear types indicated fish assemblages varied between Sacramento and San Joaquin River sampling sites. Results from gill net sampling were less pronounced than those from beach seine sampling. The Sacramento and San Joaquin river sites differed most notably in terms of water clarity and abundance of submerged aquatic vegetation (SAV), suggesting a link between these habitat characteristics and fish relative abundance. Among-site differences in the relative abundance of periodic and equilibrium strategist species suggested a gradient in the importance of abiotic versus biotic community structuring mechanisms. Fish biomass varied among years, but was generally higher in SAV-dominated habitats than the turbid, open habitats in which we found highest abundances of striped bassMorone saxatilis and special-status native fishes such as delta smeltHypomesus transpacificus, Chinook salmonOncorhyncus tschawytscha, and splittailPogonichthys macrolepidotus. The low abundance of special-status fishes in the comparatively productive SAV-dominated habitats suggests these species would benefit more from large-scale restoration actions that result in abiotic variability that mirrors natural river-estuary habitat than from actions that emphasize local (site-specific) productivity. 相似文献
7.
Lawrence P. Rozas 《Estuaries and Coasts》1995,18(4):579-590
The salt marsh surface is not a homogeneous environment. Rather, it contains a mix of different microhabitats, which vary in elevation, microtopography, and location within the estuarine system. These attributes act in concert with astronomical tides and meteorological and climatological events and result in pulses of tidal flooding. Marsh hydroperiod, the pattern of flooding events, not only controls nekton access to marsh surface habitats directly but may also mediate habitat exploitation through its influence on other factors, such as prey abundance or vegetation stem density. The relative importance of factors affecting marsh hydroperiod differ between the southeast Atlantic and northern Gulf of Mexico coasts. Astronomical tidal forcing is the primary determinant of hydroperiod in Atlantic Coast marshes, whereas predictable tides are often overridden by meteorological events in Gulf Coast marshes. In addition, other factors influencing coastal water levels have a proportionately greater effect on the Gulf Coast. The relatively unpredictable timing of marsh flooding along the Gulf Coast does not seem to limit habitat utilization. Some of the highest densities of nekton reported from salt marshes are from Gulf Coast marshes that are undergoing gradual submergence and fragmentation caused by an accelerated rise in relative sea level. Additional studies of habitat utilization are needed, especially on the Pacific and Atlantic coasts. Investigations should include regional comparisons of similar microhabitats using identical quantitative sampling methods. Controlled field experiments are also needed to elucidate the mechanisms that affect the habitat function of salt marshes. 相似文献
8.
We compared nekton use ofVallisneria americana Michx. (submerged aquatic vegetation, SAV) with marsh shoreline vegetation and subtidal nonvegetated bottom (SNB) using a
1-m2 drop sampler in the oligohaline area of Barataria Bay, Louisiana. Mean densities of most abundant species were significantly
different among six habitat types. Harris mud crabRhithropanopeus harrisii, Ohio shrimpMacrobrachium ohione, blue crabCallinectes sapidus, daggerblade, grass shrimpPalaemonetes pugio, white shrimpLitopenaeus setiferus (fall), rainwater, killifishLucania parva, naked gobyGobiosoma bosc, code gobyGobiosoma robustum (fall), speckled worm eelMyrophis punctatus (fall), and gulf pipefishSyngnathus scovelli (spring), were much more abundant, and species richness also was greater, inVallisneria than over SNB.Vallisneria supported densities of most species that were similar to those in marsh vegetation, although naked goby and gulf pipefish
were more abundant inVallisneria, and speckled worm eel and saltmarsh topminnowFundulus jenkinsi were more abundant in marsh. Within theVallisneria bed, densities of Harris mud crab, rainwater killifish, and speckled worm eel were higher at sites near the marsh (SAV Inside
Edge) than at sites more distant from the marsh (SAV Outside Edge), and Ohio shrimp (fall) densities were higher in the interior
of the bed than along the edges. The mean size of blue crab was larger in marsh thanVallisneria and large inVallisneria than SNB. White shrimp did not differ in size among habitat types.Vallisneria beds may provide an important nursery habitat for young blue crab and white shrimp that use oligohaline estuarine areas.
These SAV beds can provide an alternative structural habitat to emergent vegetation during periods of low water, becauseVallisneria occurs in the subtidal and generally persists throughout the year on the Gulf coast. Species whose young thrive in low-salinity
waters and also depend on structure would benefit most fromVallisneria habitat in estuaries. 相似文献
9.
We evaluated nekton habitat quality at 5 shallow-water sites in 2 Rhode Island systems by comparing nekton densities and biomass,
number of species, prey availability and feeding, and abundance of winter flounderPseudopleuronectes americanus. Nekton density and biomass were compared with a 1.75-m2 drop ring at 3 sites (marsh, intertidal, and subtidal) in Coggeshall Cove in Narragansett Bay and two subtidal sites (eelgrass
and macroalgae) in Ninigret Pond, a coastal lagoon. We collected benthic core samples and examined nekton stomach contents
in Coggeshall Cove. We identified 16 species of fish, 16 species of crabs, and 3 species of shrimp in our drop ring samples.
A multivariate analysis of variance indicated differences in total nekton, invertebrates, fish, and winter flounder across
the five sites. Relative abundance of benthic invertebrate taxa did not match relative abundance of prey taxa identified in
the stomachs. Nonmetric multidimensional scaling plots showed groupings in nekton and benthic invertebrate prey assemblages
among subtidal, intertidal, and marsh sites in Coggeshall Cove. Stepwise multiple regression indicated that biomass of macroalgae
was the most important variable predicting abundance of nekton in Coggeshall Cove, followed by elevation and depth. In Rhode
Island systems that do not experience chronic hypoxia, macroalgae adds structure to unvegetated areas and provides refuge
for small nekton. All sites sampled were characterized by high abundance and diversity of nekton pointing to the importance
of shallow inshore areas for production of fishes and decapods. Measurements of habitat quality should include assessment
of the functional significance of a habitat (this can be done by comparing nekton numbers and biomass), some measure of habitat
diversity, and a consideration of how habitat quality varies in time and space. 相似文献
10.
To assess the potential for habitat isolation effects on estuarine nekton, we used two species with different dispersal abilities
and life history strategies, mummichog (Fundulus heteroclitus) and pinfish (Lagodon rhomboides) to examine: (1) distribution trends among estuarine shallow-water flat and various intertidal salt marsh habitats and (2)
the influence of salt marsh habitat size and isolation. Collections were conducted using baited minnow traps set within nonisolated
interior marshes (interior), nonisolated fringing marshes (nonisolated), isolated island marshes (isolated), and shallow-water
flat habitats (flat) that were adjacent to isolated and nonisolated marshes. Size range of individuals collected included
juvenile and adult F. heteroclitus (20–82-mm standard length) and L. rhomboides (22–151-mm standard length). During high tide, F. heteroclitus exclusively used marsh habitats, particularly high marsh, whereas L. rhomboides used marshes and flats. F. heteroclitus abundance followed an interior > nonisolated > isolated pattern. L. rhomboides abundance patterns were less consistent but followed a nonisolated > isolated > interior pattern. A size-dependent water
depth relationship was observed for both species and suggests size class partitioning of marsh and flat habitats during high
tide. Minimum water depth (~31 cm) restricted L. rhomboides populations in marshes, while maximum water depth (~69 cm) restricted F. heteroclitus population use of marshes and movement between marsh habitats. Disparities in F. heteroclitus young of year contribution between isolated compared to nonisolated and interior marsh types suggests isolated marshes acted
as population sinks and were dependent on adult emigrants. Resident and transient salt marsh nekton species utilize estuarine
habitats in different ways and these fundamental differences can translate into how estuarine landscape might affect nekton. 相似文献
11.
Brian Fry Donald M. Baltz Mark C. Benfield John W. Fleeger Arian Gace Heather L. Haas Zoraida J. Quiñones-Rivera 《Estuaries and Coasts》2003,26(1):82-97
Brown shrimp (Farfantepenaeus aztecus) are an important commercial aquatic species experiencing loss of inshore marsh nursery habitat in coastal Louisiana. To
study inshore brown shrimp movements and identify aspects of essential habitat important for sustaining brown shrimp populations,
we collected juvenile brown shrimp in April and May 2000, the time of annual maximum brown shrimp abundance, in a small 1-km2 marsh area on the central Louisiana coast. Drop sampling showed average shrimp densities of 1.6–2.4 m−2 in shallow marsh ponds and seining indicated lower densities of 0.5–0.9 m−2 in nearby shallow channel and open bay sites. Smaller shrimp (< 50 mm) fed disproportionately on benthic diatoms and small
harpacticoid copepods, while large shrimp fed more frequently on larger-bodied amphipods and tanaids. We developed novel chemical
approaches to estimate patterns of shrimp residency and movement using carbon and nitrogen stable isotopic determinations.
Resident shrimp had isotopic values similar to average foods and showed consistent isotopic spacings between fast and slow
turnover tissues. Residency was highest (47–55%) in ponds and shallow channel habitats and much less in open bays and deep
channels (4–27%). There was sparse evidence for dietary specialization among individull shrimp. The results support the view
that small 10–20 mm postlarval and juvenile brown shrimp arriving in estuaries from offshore waters continue movement through
sub-optimal habitats (deep channels and open bays), but exhibit much less movement once an optimal habitat (marsh ponds or
shallow channel margins) is reached. This study also indicated that combining estimates of shrimp densities, residency, growth
rate, and mortality allows evaluation of the importance of different habitat types for shrimp production. Shallow ponds that
in many ways resemble fertile aquaculture ponds appear to be hot spots for brown shrimp production, and coastal preservation
and restoration efforts should focus on these areas as important for sustaining shrimp fisheries. 相似文献
12.
Fish communities in tidal tributaries have received considerable attention, but the relative value of nontidal tributaries (having a tidal amplitude of <?5 cm) may represent an under-valued habitat. A multi-gear sampling approach was used to collect fish and macroinvertebrates from one tidal and two nontidal tributaries to describe and compare the respective nekton communities and habitat use patterns. Nekton communities in tidal and nontidal tributaries were markedly different even though habitats were similar (e.g., temperature, DO, depths, shoreline vegetation). While catch-per-unit-effort (CPUE) of estuarine-dependent species (e.g., red drum, spot, common snook) was lower in nontidal tributaries, the overall nekton CPUE was twice that of the tidal tributary, and the community was comprised mostly of freshwater marsh species (e.g., eastern mosquitofish, sailfin molly, bluefin killifish). Based on the life histories of the fishes that differed between tributary types, the proximity of coastal inlets and availability of effective larval transport mechanisms for estuarine-dependent species may be greater determinants of community differences than factors related to tributary size or shoreline habitat type. These results recognize smaller nontidal tributaries as undervalued nursery habitats and suggest the function as secondary nursery habitats is a critical service to the overall estuarine community. 相似文献
13.
Fishes and invertebrate macrofauna (nekton) were sampled biweekly (July through October 1985) from the surface of tidal freshwater marshes. Samples were collected with flume nets at three different stream orders (orders 2, 3 and 4+) along a marsh stream order gradient. Twenty-five species of fishes (5,610 individuals, 17.072 kg preserved wet weight) representing 13 families, and three species of invertebrates (19,570 individuals, 13.026 kg preserved wet weight) were collected. The most abundant species were grass shrimp (Palaemonetes pugio), mummichogs (Fundulus heteroclitus), banded killifish (F. diaphanus), inland silversides (Menidia beryllina), and blue crabs (Callinectes sapidus). Invertebrate catches (mostly grass shrimp and blue crabs) were not significantly different among stations. Total numbers of fishes were significantly greater at both headwater (order 2) and main creek (order 3) stations than river (order 4+) stations, but catches of headwater and main creek stations were not significantly different. The relationship between marsh stream order and fish abundance may partly be related to the distribution of submerged aquatic vegetation (SAV) within marsh tidal creeks. Submerged aquatic vegetation decreases in abundance with increasing stream order. Some species may use SAV as a refuge from predators or as a foraging area during low tide when the marsh surface is inaccessible. The presence of SAV in tidal creeks may enhance the habitat value of adjacent marshes. 相似文献
14.
Subsidence and erosion of intertidal salt marsh at Galveston Island State Park, Texas, created new areas of subtidal habitat
that were colonized by seagrasses begining in 1999. We quantified and compared habitat characteristics and nekton densities
in monospecific beds of stargrassHalophila engelmanni and shoalgrassHalodule wrightii as well as adjacent nonvegetated substrates. We collected 10 replicates per habitat type during April, July, October, and
December 2001. Most habitat characteristics varied with season. Water temperature, salinity, and dissolved oxygen were similar
among habitat types. Turbidity and depth were greatest inH. engelmanni beds and least inH. wrightii beds.H. engelmanni exhibited shorter leaves and higher shoot density and biomass core−1 thanH. wrightii. Densities of almost all dominant species of nekton (fishes and decapods) were seasonally variable, all were higher in seagrass
habitats than in nonvegetated habitats, and most were higher in one seagrass species than the other. Naked gobyGobiosoma bosc, code gobyGobiosoma robustum, bigclaw snapping shrimpAlpheus heterochaelis, and blue crabCallinectes sapidus, were most abundant inH. engelmanni. Brown shrimpFarfantepenaeus aztecus, brackish grass shrimpPalaemonetes intermedius, and daggerblade grass shrimpPalaemonetes pugio were most abundant inH. wrightii. PinfishLagodon rhomboides and pink shrimFarfantepenaeus duorarum were equally abundant in either seagrass. Most dominant nekton varied in size by month, but only two (L. rhomboides andC. sapidus) exhibited habitat-related differences in size. Nekton densities in these new seagrass habitats equaled or exceeded densities
associated with historical and current intertidal smooth cordgrassSpartina alterniflora marsh. Continued seagrass expansion and persistence should ensure ecosystem productivity in spite of habitat change. 相似文献
15.
Ann Commagere Hijuelos Shaye E. Sable Ann M. O’Connell James P. Geaghan David C. Lindquist Eric D. White 《Estuaries and Coasts》2017,40(4):1183-1194
Modeling the distribution and habitat capacities of key estuarine species can be used to identify hot spots, areas where species density is significantly higher than surrounding areas. This approach would be useful for establishing a baseline for evaluating future environmental scenarios across a landscape. We developed species distribution models for early juvenile life stages of brown shrimp (Farfantepenaeus aztecus), white shrimp (Litopenaeus setiferus), blue crab (Callinectes sapidus), and spotted seatrout (Cynoscion nebulosus) in order to delineate the current coastal hot spots that provide the highest quality habitat conditions for these estuarine-dependent species in Louisiana. Response curves were developed from existing long-term fisheries-independent monitoring data to identify habitat suitability for fragmented marsh landscapes. Response curves were then integrated with spatially explicit input data to generate species distribution models for the coastal region of Louisiana. Using spatial autocorrelation metrics, we detected clusters of suitable habitat across the Louisiana coast, but only 1% of the areas were identified as true hot spots with the highest habitat quality for nekton. The regions identified as hot spots were productive fringing marsh habitats that are considered the most vulnerable to natural and anthropogenic impacts. The species distribution models identify the coastal habitats which currently provide the greatest capacity for key estuarine species and will be used in the Louisiana coastal planning process to evaluate how species distributions may change under various environmental and restoration scenarios. 相似文献
16.
Oysters can create reefs that provide habitat for associated species resulting in elevated resident abundances, lower mortality
rates, and increased growth and survivorship compared to other estuarine habitats. However, there is a need to quantify trophic
relationships and transfer at created oyster reefs to provide a better understanding of their potential in creating suitable
nekton habitat. Stable isotope analyses (δ13C and δ15N) were conducted to examine the organic matter sources and potential energy flow pathways at a created intertidal oyster
(Crassostrea ariakensis; hereinafter, oyster) reef and adjacent salt marsh in the Yangtze River estuary, China. The δ13C values of most reef-associated species (22 of 37) were intermediate between those of suspended particle organic matter (POM)
and benthic microalgae (BMI), indicating that both POM and BMI are the major organic matter sources at the created oyster
reef. The sessile and motile macrofauna colonizing the reef make up the main prey of transient nekton (e.g., spotted sea bass,
Asian paddle crab, and green mud crab), thus suggesting that the associated community was most important in supporting higher
trophic levels as opposed to the direct dietary subsidy of oysters. The created oyster reef consistently supported higher
trophic levels than the adjacent salt marsh habitat due to the dominance of secondary consumers. These results indicate that
through the provision of habitat for associated species, created oyster reefs provide suitable habitat and support a higher
average trophic level than adjacent salt marsh in the Yangtze River estuary. 相似文献
17.
Decapod crustaceans occupying seagrass, salt marsh edge, and oyster habitats within the St. Martins Aquatic Preserve along
the central Gulf coast of Florida were quantitatively sampled using a 1-m2 throw trap during July–August 1999 and March–April 2000. Relative abundance and biomass were used as the primary measures
to compare patterns of occupancy among the three habitat types. Representative assemblages of abundant and common species
from each habitat were compared using Schoener's Percent Similarity Index (PSI). In all, 17,985 decapods were sampled, representing
14 families and 28 species. In the summer sampling period, mean decapod density did not differ between oyster and seagrass
habitats, which both held greater densities of decapods than marsh-edge. In the spring sampling period oyster reef habitat
supported greater mean decapod density than both seagrass and marsh-edge, which had similar densities of decapods. Habitat-specific
comparisons of decapod density between the two sampling periods indicated no clear seasonal effect. In summer 1999, when seagrasses
were well established, decapod biomass among the three habitats was not significantly different. During spring 2000, decapod
biomass in oyster (41.40 gm−2) was greater than in marshedge (4.20 gm−2), but did not differ from that of seagrass (9.73 g m−2). There was no significant difference in decapod biomas between seagrass and marsh-edge habitats during the spring 2000 sampling
period. The assemblage analysis using Schoener's PSI indicated that decapod assemblages associated with oyster were distinct
from seagrass and marshedge habitats (which were similar). The results of this study suggest that in comparison to seagrass
and marsh-edge habitats, oyster reef habitats and the distinct assemblage of decapod crustaceans that they support represent
an ecologically important component of this estuarine system. 相似文献
18.
Ilia Rochlin Mary-Jane James-Pirri Susan C. Adamowicz Mary E. Dempsey Thomas Iwanejko Dominick V. Ninivaggi 《Estuaries and Coasts》2012,35(3):727-742
An integrated marsh management (IMM) project in an urbanized watershed on Long Island, New York, USA, aimed to mitigate salt marsh degradation and to reduce mosquito production by an innovative combination of restoration and open marsh water management methods. The grid ditch network at two treatment marshes was replaced with naturalized tidal channels and ponds. Effects of the hydrologic alterations were monitored utilizing a before–after–control–impact approach. The treatment marshes experienced a number of beneficial outcomes including a fourfold reduction in the invasive Phragmites australis and increased native vegetation cover in the most degraded portions of the marsh, increased abundance and diversity of marsh killifish and estuarine nekton species, higher shorebird and waterfowl densities, and increased avian species diversity. The successful implementation of IMM concept led to improved marsh health and diminished mosquito production. Therefore, this study may serve as a template for similar large-scale integrated salt marsh restoration projects. 相似文献
19.
Few studies concerning tide-restricted and restoring salt marshes emphasize fishes and decapod crustaceans (nekton) despite
their ecological significance. This study quantifies nekton utilization of three New England salt marshes under tide-restricted
and restoring conditions (Hatches Harbor, Massachusetts; Sachuest Point and Galilee, Rhode Island). The degree of tidal restriction
differed among marshes allowing for an examination of nekton utilization patterns along a gradient of tidal restriction and
subsequent restoration. Based on sampling in shallow subtidal creeks and pools, nekton density and richness were significantly
lower in the restricted marsh compared to the unrestricted marsh only at the most tide-restricted site (Sachuest Point). The
dissimilarity in community composition between the unrestricted and restricted marsh sites increased with more pronounced
tidal restriction. The increase in nekton density resulting from tidal restoration was positively related to the increase
in tidal range. Species richness only increased with restoration at the most tide-restricted site; no significant change was
observed at the other two sites. These patterns suggest that only severe tidal restrictions significantly reduce the habitat
value of New England salt marshes for shallow subtidal nekton. This study suggests that the greatest responses by nekton,
and the most dramatic shift towards a more natural nekton assemblage, will occur with restoration of severely restricted salt
marshes. 相似文献
20.
Large-scale marsh restoration efforts were conducted to restore normal salt marsh structure and function to degraded marshes
(i.e., former salt hay farms) in the mesohaline lower Delaware Bay. While nekton response has been previously evaluated for
the marsh surface and subtidal creeks in these marshes, little effort has been focused on intertidal creeks. Nekton response
in intertidal creeks was evaluated by sampling with seines to determine if restored (i.e., former salt hay farms restored
in 1996) and reference (i.e., natural or relatively undisturbed) salt marshes were utilized by intertidal nekton in a similar
manner. The overall nekton assemblage during June–October 2004–2005 was generally comprised of the same species in both the
restored and reference marshes. Intertidal creek catches in both marsh types consisted primarily ofFundulus heteroclitus andMenidia menidia, with varying numbers of less abundant transient species present. Transient nekton were more abundant at restored marshes
than reference marshes, but in insufficient numbers to cause differences in nekton assemblages. In both marsh types, low tide
stages were characterized by resident nekton, dominated byF. heteroclitus, while high tide stages were characterized by a variable mix of transient and resident nekton. Assemblage level analyses
indicated that intertidal creeks in restored and reference marshes were generally utilized in a similar manner by a similar
nekton assemblage, so restoration efforts were deemed successful. This is in agreement with multiple comparative studies from
the ame marshes examining fish, invertebrates, and vegetation in different marsh habitats. 相似文献