共查询到20条相似文献，搜索用时 31 毫秒
1.
During the year 1978, juvenile salmonids were collected from coastal streams running through China Poot Marsh and the stomach contents analyzed. Stomach contents of threespine stickleback (Gasterosteus aculeatus) and staghorn sculpin (Leptocottus armatus) from China Poot and of threespine stickleback from Potter Marsh were also analyzed; these two species were generally caught in tidal pools on the marshes. The juvenile coho salmon (Oncorhynchus kisutch) had the most varied diet; 37 different prey items were identified in the stomachs. By comparison, 25, 26, and 33 prey taxa were identified in the stomach contents of Dolly Varden char (Salvelinus malma), threespine stickleback, and staghorn sculpin, respectively. Amphipods were the dominant prey of all fish collected from China Poot Marsh; chironomidae larvae were the most common item in the stomach contents of threespine stickleback from Potter Marsh. The diets of all species changed over the course of the study period; the change was most dramatic for juvenile salmonids and sculpins. 相似文献
2.
Quantifying the trophic dynamics of mesopredators in coastal habitats is an essential precursor to understanding their role in linking multiple trophic levels. Traditional dietary analyses may miss key aspects of a species’ feeding ecology and may thus fail to identify trophic linkages between predators and economically important prey populations. We applied stomach content and stable isotope analyses to estimate diet and trophic dynamics and investigated intraspecific dietary diversity of bonnetheads (Sphyrna tiburo) and red drum (Sciaenops ocellatus). Both juvenile and adult bonnetheads and juvenile red drum had diets comprised mainly of crustaceans, notably portunid crabs and penaeid shrimp, with varying degrees of dietary and isotopic niche overlap. Juvenile and adult bonnetheads had high dietary and isotopic niche overlap, whereas the degree of overlap between bonnetheads and red drum varied. Our findings indicate that bonnetheads are dietary specialists whereas red drum are dietary generalists. Further analysis identified intraspecific variability in the diet of each species; adult bonnetheads had the highest prey diversity whereas red drum had the lowest. We show that dietary and isotopic niche overlap and intraspecific variation in diet exist among juvenile and adult bonnetheads and juvenile red drum, though to varying degrees. Our findings demonstrate the importance of fully examining the trophic ecology of species that share habitats and resources, both at individual and population levels. 相似文献
3.
Menhaden are one of the most abundant components of fish communities in Gulf and Atlantic estuaries. Juvenile menhaden have been reported to have zooplankton, phytoplankton, andSpartina-derived detritus in their guts. However, there has been disagreement over the importance of the detritus as a food source. We show, using physiological and stable isotope evidence, that detritus can be used by juvenile Gulf menhaden. Their diet is very roughly 30% detritus- and 70% plankton-based. 相似文献
4.
Maintaining proper freshwater and marine inputs is essential for estuarine function. Alteration of freshwater flows into small
tributaries that traverse the upland-estuarine margin may be especially problematic, e.g., by impacting the nursery areas
for juvenile finfish and shellfish. We used stomach contents and stable isotope analysis (δ13C, δ15N) to examine effects of freshwater flow alterations on the trophic ecology of juvenile common snook (Centropomus undecimalis) in four mangrove creeks with different freshwater flow regimes. Diet diversity in less degraded creeks was greater than
in more degraded creeks, and the importance (by % mass) of the top three preys was disproportionately higher in the more degraded
creeks. Stable isotope measures of trophic diversity corroborate these trends, suggesting higher intraspecific trophic diversity
in less degraded creeks. The difference in diet diversity of juvenile snook may be an indicator of an overall change in ecosystem
function and these shifts in food web structure may affect the rate that juveniles of this and other species with similar
habitat requirements successfully join the adult population. 相似文献
5.
Small, abundant elasmobranchs use shallow marine areas (<20 m depth) of the US Middle Atlantic coast as nurseries and adult
foraging habitat, an area also used by a diverse assemblage of economically important juvenile and adult teleost species.
Specimens of three small elasmobranch species (smooth dogfish Mustelus canis, clearnose skate Raja eglanteria, and bullnose ray Myliobatis freminvillii) were collected in August 2007 and 2008 from a study area of ∼150 km2, extending 22 km south from Ocean City, Maryland, USA (38° 19′ N) and offshore from 5- to 20-m depth. Stomach contents indicated
that fish were part of the diets of smooth dogfish and clearnose skate at a level comparable with sympatric piscivorous teleosts.
However, stable isotope data suggest that piscivory is likely an opportunistic foraging behavior in this habitat. Studied
elasmobranchs were secondary-tertiary consumers with diets composed primarily of decapod crustaceans, fish, and mollusks.
There was significant overlap in diet composition, spatial distribution, and diel stomach fullness patterns between clearnose
skate, southern kingfish Menticirrhus americanus (teleost) and, to a lesser extent, smooth dogfish. Despite this evidence for piscivory, their relatively low densities suggest
that predation by these elasmobranchs is unlikely to affect teleost populations in shallow coastal ocean habitats. If shared
prey were to become scarce, then competitive interactions are possible. 相似文献
6.
Quantitative reconstruction of paleodiet by means of sequential sampling and carbon isotope analysis in hypsodont tooth enamel requires a precise knowledge of the isotopic enrichment between dietary carbon and carbon from enamel apatite (εD-E), as well as of the timing and duration of the enamel mineralization process (amelogenesis). To better constrain these parameters, we performed a series of controlled feeding experiments on sheep ranging in age from 6 to 24 months-old. Twenty-eight lambs and 14 ewes were fed isotopically distinct diets for different periods of time, and then slaughtered, allowing the timing and rate of molar growth to be determined. High resolution sampling and stable carbon isotope analysis of breath CO2 performed on six individuals following a diet-switch showed that 70-90% of dietary carbon had turned over in less than 24 h. Sequential sampling and carbon isotopic analysis was performed on the first (M1) and second (M2) lower molars of four lambs as well as on the third lower molar (M3) of 11 ewes. The changes in diet were recorded in all molars. We found that the length of enamel matrix apposition is approximately one-quarter of the final tooth length during crown extension, and that enamel maturation spans slightly less than 3 months in M1, and 4 months in M2 and M3. Portions of enamel in equilibrium with dietary carbon were used to calculate εD-E values. Animals on grass silage diets had values similar to previous observations, whereas animal switched to pelleted corn diets had values ca. 4‰ lower, a pattern consistent with lower methane production observed for animals fed concentrate diets. The tooth enamel forward model of Passey and Cerling (2002) closely predicted the amplitude of isotope changes recorded in tooth enamel, but slightly underestimated the rate of isotope change, suggesting that the rate of accumulation of carbonate during maturation may not be constant over time. Although stable isotope profiles in tooth enamel represent underdetermined systems, our results demonstrate that they can provide useful information about dietary variability if the mineralization process is taken into account. 相似文献
7.
Feeding habits, seasonal diet variation, and predator size-prey size relationships of red drum (Sciaenops ocellatus) were investigated in Galveston Bay, Texas through stomach contents analysis. A total of 598 red drum ranging from 291–763 mm total length were collected and their stomach contents analyzed during fall 1997 and spring 1998. The diet of red drum showed significant seasonal patterns, and was dominated by white shrimp (Penaeus setiferus) during fall and gulf menhaden (Brevoortia patronus) during spring. Blue crab (Callinectes sapidus) was an important component of red drum diets during both seasons. Significant differences existed between prey types consumed during fall and spring as red drum diet reflected seasonal variation in prey availability. Predictive regression equations were generated to estimate original carapace width of blue crabs from several measurements taken from carapace fragments recovered in red drum stomachs. Regressions were highly significant (r2>0.97) and increased the number of blue crabs with size information nearly three fold. Predator size-prey size relationships were determined for red drum feeding on white shrimp, gulf menhaden, and blue crab. Although regression slopes were statistically significant, prey sizes increased only slightly with increasing red drum size. Comparisons of prey sizes consumed by red drum with sizes occurring in the field indicate that red drum feed in nearshore shallow water habitats, which serve as nursery areas for many juvenile fishes and crustaceans. Our findings demonstrate that red drum feed on several prey species of commercial and recreational value and may have important effects on estuarine community structure. 相似文献
8.
Killifish are ecologically important components of salt marsh ecosystems, but no studies have determined the importance of
locally produced versus allochthonous food sources on a scale of less than multiple kilometers. The goal of our study was
to examine diet and movement of the killifish,Fundulus heteroclitus, collected from a Maine salt marsh to assess the importance of locally produced versus allochthonous food sources on a scale
of several hundred meters. We compared the gut contents and stable isotope signatures ofF. heteroclitus from four regions along the central river of a Maine salt marsh to the distinct food sources and isotopic signatures of the
region of the marsh in which they were caught.F. heteroclitus were relying on locally produced food sources even on the scale of several hundred meters. They fed daily in a small area
less than 6 ha and maintained relatively strong site fidelities over the course of several months. Phytoplankton and salt
marsh detritus both contributed to the high production ofF. heteroclitus; terrestrial plant detritus was not an important component of their diet. The diet and feeding patterns ofF. heteroclitus from this small Maine salt marsh were similar to the patterns found in much larger salt marshes, suggesting that locally
produced organic matter is essential to the production of these ecologically important fish. 相似文献
9.
《Quaternary Science Reviews》2007,26(9-10):1332-1343
The growth of a well-dated stalagmite from Barbados records high infiltration rates into the karst aquifer and hence increased rainfall intensity between 6.7 and 3 ka BP in agreement with records from Lake Miragoane, Haiti [Hodell et al., 1991. Reconstruction of the Caribbean climate change over the past 10,500 years. Nature 352, 790–793], mainly reflecting the insolation maximum of the Northern Hemisphere. Both the lake record and the stable isotope record of the stalagmite reveal additional centennial variability of recharge. High oxygen isotope values in stalagmite calcite, corresponding to reduced recharge, are synchronous with periods of lower stable isotope values recorded in Lake Miragoane ostracods, previously attributed to enhanced precipitation. Accordingly, periods of increased recharge in Barbados correspond to 18O-enriched isotope values of ostracods, which were attributed to higher evaporation/precipitation ratios in the lakes. We ascribe this apparent discrepancy to changes in seasonality, i.e., winter periods of reduced temperature and relative humidity following summer months of increased precipitation. At present, such climate conditions occur during periods of enhanced Northern Atlantic Oscillation (NAO+). If enhanced seasonality is a consequence of a NAO+ situation, the apparent discrepancy of high isotope values in lakes (previously attributed to droughts) can be reconciled with lower winter temperatures in the lakes. Further, the correlation of solar intensity (derived from 14C and 10Be) with the isotopic signals recorded in the lacustrine sediments suggests a solar forcing of the NAO during the mid Holocene. 相似文献
10.
Violette Marchais Gauthier Schaal Jacques Grall Anne Lorrain Caroline Nerot Pierre Richard Laurent Chauvaud 《Estuaries and Coasts》2013,36(4):808-819
This study aimed at characterizing the diet of the oyster Crassostrea gigas along an estuarine gradient in the Bay of Brest (France), through stable isotope (δ13C and δ15N) measurements in primary producers and wild oysters. The contribution of different potential food sources to the diet of C. gigas was estimated at high spatial resolution (over a gradient of 40 km with samplings every 2 km) to identify ecological transition zones and highlighted the dominance of resuspended biofilm in oysters diet. Although the different primary producers did not display any obvious pattern along the estuarine gradient, the stable isotope signatures of C. gigas differed among estuarine, inner Bay, and open sea sites. In particular, a striking 15N depletion pattern was found along the gradient which allowed to identify seven homogeneous groups. Moreover, some unexpected values found at two stations within the estuary revealed localized anthropogenic disturbances. Overall, our results suggest that suspension feeders might be better indicators of ecosystem functioning than primary producers and reflect the different ecological processes occurring along estuarine gradients, including localized anthropogenic inputs. We suggest that the usefulness of suspension feeders as indicators of ecosystem functional typology lies in the dominance of benthic material in their diet, which results in locally occurring processes being reflected in oysters’ stable isotope ratios. 相似文献
11.
Bernd R. Schöne Nicholas A. Page David L. Rodland Jens Fiebig Sven Baier Samuli O. Helama Wolfgang Oschmann 《International Journal of Earth Sciences》2007,96(3):525-540
We present the results of sclerochronologically calibrated growth and stable isotope analyses of the freshwater bivalve Margaritifera falcata collected from an agricultural, suburban setting near Vancouver, BC. The oxygen isotope range of shell aragonite can be explained by the temperature range during the growing season, assuming the water δ 18O composition remained constant. However, shell growth is strongly influenced by local summer precipitation and potentially runoff of nutrient-rich stormwater. About 44% of the variability of annual shell growth can be explained by amounts of local summer (June–September) rainfall. Local winter precipitation and El Niño–Southern Oscillation (ENSO) strength during the preceding year exert a weak, but significant control on shell growth. In combination, summer and winter precipitation can explain up to 50% of the variability in annual shell growth. Spectral analyses substantiate the effect of precipitation on shell growth and demonstrate that shell growth and ENSO are coupled by precipitation. Common spectral density was found at periods of 6.5–9 years, particularly between 1985 and 2004. Higher frequency oscillation corresponding to periods of 3–5 years occurred during the early 1970s, early to mid 1980s, and later 1990s. These results suggest that skeletal records of bivalve mollusks provide suitable archives of ENSO-coupled precipitation in areas where other climate proxies such as tree-rings and speleothems may not be available. 相似文献
12.
Prey availability and feeding success affect survival of larval striped bass (Morone saxatilis) in Chesapeake Bay and contribute to the >30-fold interannual recruitment variability. Gut contents and stable isotope analyses (δ15N and δ13C) were conducted on striped bass larvae to evaluate sources of nutrition in 2007 and 2008, years of high and poor recruitment, respectively. Ichthyoplankton and zooplankton were surveyed in the upper Chesapeake Bay, in proximity to the estuarine turbidity maximum and associated salt front. Feeding incidence and numbers of prey per gut were similar in both years and varied in relation to the salt front. The primary prey in each year was the estuarine copepod Eurytemora affinis. Substantial consumption of the freshwater cladoceran Bosmina spp. also occurred, especially up-estuary of the salt front in 2007, demonstrating that secondary prey are important to larval diets in some years. Stable isotope analysis of yolk sac and feeding-stage larvae of striped bass revealed an ontogenetic shift from maternal stable isotope signatures to those indicative of prey source. Feeding-stage larvae from up-estuary locations had the most negative δ13C values, indicating a relatively high terrestrial carbon source in prey. Spatio-temporal variability in δ15N signatures of larvae followed similar trends of δ15N variability in zooplankton prey with the highest δ15N values up-estuary of the salt front and estuarine turbidity maximum. A stable isotope analysis on archived striped bass larvae collected in 1998 and 2003, years of moderate and high recruitment, respectively, expanded the documented range of isotope signatures but did not clearly distinguish effects of nutritional sources on recruitment. 相似文献
13.
Roy T. Churchwell Steve Kendall Stephen C. Brown Arny L. Blanchard Tuula E. Hollmen Abby N. Powell 《Estuaries and Coasts》2018,41(1):280-292
River deltas along Alaska’s Beaufort Sea coast are used by hatch-year semipalmated sandpipers (Calidris pusilla) after leaving their terrestrial natal sites, but the drivers of their use of these stopover sites on the first “hop” of fall migration are unknown. We quantified sandpiper temporal distribution and abundance as related to food resources at three river deltas during the beginning of their fall migration (post-breeding period) to compare the habitat quality among these deltas. We conducted population counts, sampled invertebrates, and captured birds to collect blood samples from individuals for triglyceride and stable isotope analyses to determine fattening rates and diet. Patterns of sandpiper and invertebrate abundance were complex and varied among deltas and within seasons. River deltas were used by sandpipers from late July to late August, and peak sandpiper counts ranged from 1000 to 4000 individuals, of which 98% were hatch-year semipalmated sandpipers. Isotopic signatures from blood plasma samples indicated that birds switched from a diet of upland tundra to delta invertebrate taxa as the migration season progressed, suggesting a dependence on delta invertebrates. Despite differences in diet among deltas, we found no differences in fattening rates of juvenile sandpipers as indicated by triglyceride levels. The number of sandpipers was positively associated with abundance of Amphipoda and Oligochaeta at the Jago and Okpilak-Hulahula deltas; an isotopic mixing model indicated that sandpipers consumed Amphipoda and Oligochaeta at Jago, mostly Chironomidae at Okpilak-Hulahula and Spionidae at Canning. Regardless of the difference in sandpiper diets at the Beaufort Sea deltas, their similar fattening rates throughout the season indicate that all of these stopover sites provide a critical food resource for hatch-year sandpipers beginning their first migration. 相似文献
14.
Establishing links between migration patterns and trophic dynamics is paramount to ecological studies investigating the functional role habitats provide to resident and transient species. Natural tags in fishes, such as otolith chemistry and tissue stable isotopes, can help reconstruct previous environmental and dietary histories, although these approaches are rarely combined. A novel multiproxy natural tag approach was developed to estimate immigration patterns of juvenile Atlantic croaker Micropogonias undulatus, across contrasting salinity gradients in three subtropical estuaries of the western Gulf of Mexico. Juvenile young-of-year Atlantic croaker were collected along a latitudinal gradient that included positive, neutral, and negative estuaries, based on physicochemical (temperature, salinity, dissolved element) and isotopic (δ15N and δ13C) parameters. Otolith elemental chronologies of Sr/Ca and Ba/Ca were used to classify migratory types within each estuary, while tissue-specific isotope ratios revealed time since recent (liver~weeks) and longer term (muscle~months) diet shifts. Nitrogen isotopes in both liver and muscle tissues were highly correlated, suggesting tissue equilibrium and estuarine residence of at least 3 months, with geographic δ15N gradients reflecting the magnitude of anthropogenic nutrient enrichment within each estuary. Differences in isotopic equilibrium of muscle-liver δ13C values and variation in marginal edge otolith Sr/Ca and Ba/Ca suggested recent shifts in carbon source and habitat utilization, reflecting individualized movement across seascapes and connectivity of habitat mosaics. The multiproxy approach presented here identified diverse migration patterns and linked feeding and movement on regional (inter-estuary), local (intra-estuary), and individual scales to improve our understanding of habitat function across estuarine gradients. 相似文献
15.
The Laguna Madre of South Texas is a shallow coastal lagoon whose dominant primary producers shifted from seagrasses to phytoplankton with the onset of the Texas brown tide, which persisted from 1990 through 1997. Acartia tonsa is the dominant component of the mesozooplankton and forms an important link in both the phytoplankton and detritus-based pelagic food webs. Stable carbon isotope ratios of A. tonsa, as well as the two major primary producers: phytoplankton (as particulate organic carbon) and seagrasses, were measured from March 1989 to October 1991. Zooplankton samples were collected at four locations in the Laguna Madre: two in shallow water (c. 1 m) over seagrass beds and two in slightly deeper water (c. 2–3 m) over a muddy bottom in a secondary bay without seagrasses. We found seasonal trends in the isotopic composition of A. tonsa collected within both habitats as well as distinct differences between the average {ie995-1} values of individuals collected in the two regions. Isotopic ratios of animals collected during the summer months were generally 4–8‰ enriched in 13C compared with those collected in the winter, at all stations. A. tonsa collected over seagrass beds were 2–5‰ more enriched in 13C than those collected over muddy bottoms. These observations suggest carbon derived from seagrasses can be an important source of nutrition for these copepods in summer, especially for copepods living over seagrass beds. The effects of the persistent brown tide decreased the contribution of seagrasses as a carbon source for A. tonsa during the summer of 1991. The pathway by which seagrass carbon enters the diet of A. tonsa is unclear, but the two pathways considered most likely are through copepods feeding on microzooplankton that have fed on bacteria nourished on seagrass carbon, or by copepods feeding directly on particles of seagrass detritus. 相似文献
16.
The benthic amphipod Ampelisca abdita dominates mudbottom benthic communities in Jamaica Bay (New York). In this study, we investigated the trophic role of Ampelisca in relation to winter flounder (Pleuronectes americanus) populations—the most frequently trawled fish species in Jamaica Bay. Flounders collected by trawl during summer 1989 were primarily juveniles. Stomach analyses indicated that amphipod crustaceans contributed >99% of prey individuals, with A. abdita making up 88%. Density and size frequency analyses of Ampelisca at three sites indicated two overlapping cohorts: a spring cohort released in June and a summer cohort released in late summer. Most overwintering survivors come from the summer cohort. Secondary production of Ampelisca was estimated at three sites using the cohort summation of biomass method. Estimates of annual production ranged from 25 g DW to 47 g DW m?2 (mortality + residual biomass); production due to growth ranged from 20 g DW to 26 g DW. Simulations of spring cohort production using a range of plausible growth and mortality schedules suggested that P∶B may be more sensitive to variability in survivorship than growth. Ampelisca secondary production in Jamaica Bay is compared with other amphipod species and with macrobenthic production in other coastal and estuarine systems. We conclude that observed amphipod production is probably more than sufficient to support local winter flounder populations in Jamaica Bay, and we speculate that high nutrient loadings may indirectly stimulate amphipod production. *** DIRECT SUPPORT *** A01BY058 00010 相似文献
17.
Aaron T. David Charles A. Simenstad Jeffery R. Cordell Jason D. Toft Christopher S. Ellings Ayesha Gray Hans B. Berge 《Estuaries and Coasts》2016,39(3):767-780
During the transition of juveniles from fresh water to estuarine and coastal environments, the survival of Pacific salmon (Oncorhynchus spp.) can be strongly size selective and cohort abundance is partly determined at this stage. Because quantity and quality of food influence juvenile salmon growth, high rates of prey and energy acquisition during estuarine residence are important for survival. Human activities may have affected the foraging performance of juvenile salmon in estuaries by reducing the area of wetlands and by altering the abundance of salmon. To improve our understanding of the effects of wetland loss and salmon density on juvenile salmon foraging performance and diet composition in estuaries, we assembled Chinook salmon (Oncorhynchus tshawytscha) diet and density data from nine US Pacific Northwest estuaries across a gradient of wetland loss. We evaluated the influence of wetland loss and density on juvenile Chinook salmon instantaneous ration and energy ration, two measures of foraging performance, and whether the effect of density varied among estuaries with different levels of wetland loss. We also assessed the influence of wetland loss and other explanatory variables on salmon diet composition. There was no evidence of a direct effect of wetland loss on juvenile salmon foraging performance, but wetland loss appeared to mediate the effect of density on salmon foraging performance and alter salmon diet composition. Specifically, density had no effect on foraging performance in the estuaries with less than 50 % wetland loss but had a negative effect on foraging performance in the estuaries with greater than 50 % wetland loss. These results suggest that habitat loss may interact with density to constrain the foraging performance of juvenile Chinook salmon, and ultimately their growth, during a life history stage when survival can be positively correlated with growth and size. 相似文献
18.
We quantified temporal and spatial variability in diets of 950 juvenile (age-0) striped bass in the Hudson River estuary.
We used canonical correspondence analysis to assess the roles of temporal and spatial habitat variability in juvenile diet
variation. We found that juvenile striped bass diets in the Hudson River were only modestly comparable to diets in other east
coast estuaries. Among-year differences (51.4%) and spatial differences (41.9%) were substantially associated with juvenile
striped bass diet. We found ontogeny (2.8%) and within-season variation (9.5%) to only weakly associate with diet variation.
Our results indicate that an understanding of the temporal and spatial variation within the Hudson River estuary is vital
in understanding variation in feeding by resident juvenile fish. 相似文献
19.
Our objective was to quantify the contribution of autochthonous, locally-produced phytoplankton, and allochthonous, terrestrial-derived
organic matter (OM) to the production of young-of-year (YOY) American shad(Alosa sapidissima) using stable isotopes. We measured the carbon and nitrogen stable isotope composition of YOY American shad in the tidal fresh
water of the Mattaponi River, a tributary in the York River estuary, during three consecutive years. The isotopic ratios of
larval American shad varied among years, indicating a switch from reliance on a primarily autochthonous food web pathway during
low and moderate discharge years (50–90%; 2002, 2004) to a primarily allochthonous pathway during a high discharge year (<
35% phytoplankton; 2003). Reliance on phytoplankton by larval fish declined exponentially with increasing Mattaponi River
discharge. In 2003, juvenile production was also supported by allochthonous OM, though autochthonous phytoplankton accounted
for an increasingly large fraction during June through August, up to 40–55%. We also found a long-term, positive relationship
between the duration of above average flow during April through June in the Mattaponi River and a corresponding index of juvenile
American shad abundance. The largest American shad cohort recorded since 1967 was observed in 2003, a high discharge year.
The production of this cohort was largely supported by allochthonous OM. The results suggest an important link between river
discharge, energy flow, and recruitment, wherein high discharge favors reliance on terrestrial carbon by YOY American shad,
owing to changes in zooplankton diet, macroinvertebrate abundance, or both, and also favors high American shad abundance. 相似文献
20.
Dispersion of the salt-marsh periwinkle Littoraria irrorata: Effects of water level,size, and season
This paper documents horizontal and vertical dispersion patterns of a Texas population of the saltmarsh periwinkle, Littoraria irrorata, over a 15-month period. The study was conducted within a tidal marsh on the Anahuac National Wildlife Refuge in Galveston Bay. Two mark-recapture experiments demonstrated that L. irrorata rarely move more than 2 m from their release point over long periods of time and do not home to individual Spartina plants. Adult L. irrorata forage farther away from the base of Spartina stalks at low tide than do juvenile snails. Remaining near the plant base may decrease both temperature and desiccation stress on juveniles. During warm months, L. irrorata climb grass stalks with tidal inundation and forage on the substratum at low tide. Snails are inactive and aggregate in detrital debris at the base of Spartina clumps during the winter. *** DIRECT SUPPORT *** A01BY058 00016 相似文献