Marsh Pools Research Articles

Microbial Eukaryotes in Natural and Artificial Salt Marsh Pools

Microscopic eukaryotes are important components of coastal wetland ecosystems. The goal of this study was to investigate the diversity of microeukaryotes in the tidal pools of a New Jersey salt marsh and to compare the assemblages of natural and artificial pools excavated for controlling mosquito populations. We evaluated microeukaryotic assemblages using the amplicon sequencing of 18S and rbcL DNA markers and the microscopic identification of diatoms in water and sediment samples. 18S unique amplicon sequence variants (ASV) representing ciliates, dinoflagellates, diatoms, and cercozoans were the most diverse, while the reads of dinoflagellates, diatoms, ciliates, and nematodes were the most abundant. The dominant ASVs were attributed to organisms that are characteristic of coastal plankton and sediments or those known for their resistance to salinity, desiccation, hypoxia, and UV stress. The sediment assemblages were more diverse compared to those from the water column and contained a larger portion of ASVs that were not assigned to any low-rank taxa, reflecting the current gaps in understanding the diversity of microeukaryotes. Most taxonomic groups were significantly different in their abundance and composition between natural and artificial pools. Dinoflagellates, haptophytes, chrysophytes, pelagophytes, and raphidophytes—the groups that include a large proportion of mixotrophic taxa and species known for forming harmful algal blooms—were more abundant in the artificial than in the natural pools. Fungi, labyrinthulomycetes, and peronosporomycetes were also more abundant in artificial pools, which may be related to organic matter enrichment. Diatoms and foraminifera showed an opposite trend of higher abundance in natural pools.

Invertebrate communities of Bay of Fundy salt marsh pools: comparison of a natural and recovering marsh

Disturbed salt marshes may recover with little additional management once tidal inundation is restored. We assessed the success of such recovery by comparing the invertebrate biota of Bay of Fundy salt marsh pools in a reference site at Dipper Harbour to that of Saints Rest marsh that had been drained for over a century and to which tidal flooding had been returned ~50 years prior to our study. The sediments and vegetation of salt marsh pools were sampled seasonally throughout one year. Average biomass of pool invertebrates ranged from 1.8 to 4.0 g dry wt m−2, depending on the amount of vegetation cover in the pools. The most abundant organisms of the pools were the gastropod Ecrobia truncata (=Hydrobia tottentei), Tubificidae (=Naididae) oligochaetes, and Chironomidae (=Chironomini). We compared overall abundance and biomass of the invertebrates in the pool communities, assessing the month of sampling, pool elevation, and source marsh as explanatory variables. Our analyses revealed that marsh origin of pools seldom explained a significant amount of variance, and when it did, the proportion of variance explained was usually lower than elevation of pools and month of sampling. Diversity of invertebrates found in all pools was higher at the recovering site with species richness >40% higher than in the reference site. We conclude that after an estimated 50 years since dyke failure and return of tidal flooding to Saints Rest marsh, that the ecosystem function represented by pools and their fauna has recovered.

Age of Tarpon (Megalops atlanticus) Leptocephali Recruiting to Salt Marsh Pools in a South Carolina Estuary

To increase our knowledge of the early life history of Megalops atlanticus (Tarpon) along the United States Atlantic coast north of Florida, we estimated the age and hatch dates of Tarpon larvae (i.e., leptocephali) recruiting to salt marsh pools in the North Inlet estuary, SC. We collected leptocephali (n = 36) from marsh pools during June through October 2016 and kept a subset (n = 24) of these individuals for aging. We were able to estimate ages for 18 individuals by counting presumed daily rings on their otoliths. We estimated hatch date by subtracting estimated age from the capture date. Mean age was 25 days post hatch (dph) and varied from 17 to 30 dph. Hatch dates spanned from 25 July to 9 September 2016. These are the first age and hatch date estimates for Tarpon leptocephali from estuaries north of Florida and provide insight into the biology and possible spawning behavior of Tarpon in this area of the US Atlantic coast.

Selection of Estuarine Feeding Habitats by Snowy and Great Egrets in the Great Marsh Estuary, Northeastern Massachusetts, USA

The feeding habitats of Great (Ardea alba) and Snowy (Egretta thula) egrets at the Great Marsh in Northeastern Massachusetts, USA, were characterized through field observations over two years during the breeding seasons of 2012 and 2013. Both species were from a large breeding colony making a daily commute to the Great Marsh for foraging. Habitats at the Great Marsh were delineated as marsh pools, the vegetated marsh, impoundments, open water, tidal flats, and tidal creeks and ditches. Observations (45 counts in 2012 and 48 in 2013) consisted of recording the number of birds, behavior (feeding or not), habitat, and the time of observation and relating these observations to the tidal cycle. The preferred feeding habitats of Snowy Egrets were in marsh pools and along the edges of large impoundments. The preferred feeding habitats of Great Egrets were on the marsh platform, particularly at high tides, and marsh pools. An analysis of physical characteristics with locations of feeding sites revealed no consistent patterns. Certain sites would occasionally support large numbers of feeding Great and Snowy egrets one day only to be ignored the next day at the same tide. The results suggest that Great and Snowy egrets are opportunistic in their selection of feeding sites at the Great Marsh. A future of wetter marshes might provide more feeding opportunities for Great and Snowy egrets, at least in the short-term.

The giant quaternary Ballik travertine system in the Denizli basin (SW Turkey): a palaeoenvironmental analysis

This research forms the basis for the applicability of the Dunham (1962) classification of carbonated rock lithofacies to the analysis of the giant Ballik travertine architecture, while reconstructing lateral and vertical environmental changes. This study provides an analogue for spring-related deposits encountered offshore Brazil and Angola by linking macroscopically travertine lithofacies distribution to depositional environments. The analysis is based on rock-building constituents such as gastropods, charophytes, intraclasts, phytoclasts, coated grains, dendrites etc., forming micro-sedimentary fabrics with different structures such as packstone, grainstone, wackestone and boundstone, these latter closely associated with crust of dendrites and phytoherm of reeds and bryophytes. Our findings indicate that the Ballik travertine area consists of a “Lower” and an “Upper Domain” reflecting different depositional environments. More specifically, the “Lower Domain” consists from west to east of a laterally complex amalgamation of extended pool, marsh pool and flood plain environments that formed from a mixture of spring and ground waters. The extended pond environment characterised by a boundstone facies of stromatolites in the west evolves eastward into a marsh pool and flood plain. This is because CO2 degassing and water temperature decreased as the water depth of the Lower Domain reduced towards the east. The marsh pool environment includes packstone to grainstone lithofacies and abundant wackestone lithofacies made of phytoclasts, whose crusts exhibit pustular fabrics. Moreover, the flood plains along with the marsh pool consist dominantly of packstone to grainstone lithofacies with many gastropods and intraclasts, interfingered with wackestone lithofacies made of phytoclasts. Irregular clotted fabrics, along with coated grains with radial fibres, high lime mud content with bioturbation are also present. The “Upper Domain” displays a laterally less heterogeneous palaeoenvironmental distribution with flooded slope and flood plain deposits. The eastern part of the “Upper Domain” is characterized by a systematic alternation of these environments, with intercalations of wackstone lithofacies made of phytoclasts, packstone to grainstone lithofacies made of intraclasts and lime muds as well as coated grains. The flood plain has coated grains having peloidal nuclei and coatings of sparry laminations and clotted fabric of peloids representing intraclasts, whereas, the flooded slope possesses coated grains with coatings of dendrites and nuclei of peloids, boundstone of stromatolites which have flat‑laminated and columnar-laminated fabrics indicating a laminar discharge away from the spring(s). Alluvial fan and palustrine deposits with abundant bryophytes and reeds frequently interfinger with marsh pool environment in the “Lower Domain”, and with the flood plain and flooded slope environments in the “Upper Domain”. The results illustrate well how environmental changes identified in the two different domains have induced heterogeneity in reservoir‑based depositional architecture.

Lateral and vertical variations in sedimentology and geochemistry of sub-horizontal laminated travertines (Çakmak quarry, Denizli Basin, Turkey)

The laterally extensive sub-horizontal laminated travertine deposits outcropping in the Çakmak quarry (Denizli Basin, Turkey) allows reconstructing their three-dimensional geobody architecture. Based on field observations, detailed petrographic and geochemical analyses (stable carbon and oxygen isotopes, major and trace elements) the most important controlling porosity-permeability parameters in this lacustrine-dominated facies, in relation to microfacies and diagenetic modifications were constrained. Sedimentological analyses and the observed architectural geometries allowed to subdivide the sub-horizontal carbonate succession into three main depositional units. These units in turn, based on macro- and microscopic observations were subdivided into nine dominant lithotypes reflecting an overall shrub flat and a marsh pool depositional setting. The shrub flat facies mainly comprises dendritic shrub crusts boundstone, pustular grainstone and clotted micrite mudstone to boundstone. In contrast, the marsh pool environment is dominated by coated reed rudstone to boundstone, cryptalgal silty bioclast-rich bioturbated mudstone and peloidal packstones.The diagenetic study revealed that the sediments were affected by dissolution, cementation, sparmicritization, recrystallization, and local formation of Fe-oxi/hydroxides and chalcedony. Among the diagenetic products, in particular, the calcite cements were investigated, applying micro-analysis of stable carbon and oxygen isotopes. Accordingly, the co-variation between the obtained isotopic values and the elemental concentrations (Sr, Mg, Na, and S) point to a thermogene fluid system that likely circulated through the subsurface limestones, dolomites and evaporites of the Lycian Nappes. These findings ensure an in-depth understanding of continental carbonate deposition, i.e. sub-aqueous travertines, in the context of a lacustrine depositional system.

The Nekton Assemblage of Salt Marsh Pools in a Southeastern United States Estuary

Marsh pools are present in estuaries throughout the world and provide valuable habitat for fishes and decapod crustaceans (i.e., nekton). The purpose of our study was to examine the species composition and temporal variation of the nekton assemblage within marsh pools of a southeastern US estuary. We conducted weekly sampling of five marsh pools in the North Inlet estuary, SC from May to November 2016. Temporal variation in the nekton assemblage appeared to be related to the life history of individual species, tidal connectivity of pools with adjacent habitats, and environmental conditions within pools. Most transient species, which migrate into the North Inlet estuary as larvae or juveniles, were present primarily in early summer and late fall. Many transient species were absent or occurred in low abundance during July and August when water temperature was highest, salinity most variable, and tidal connectivity with adjacent habitats was lowest. In contrast, most resident species, which can complete their entire life cycle within the North Inlet estuary, were present and relatively abundant throughout the study as juveniles and adults. Based on the limited studies available, species richness and the ratio of transient to resident species in marsh pools at low latitudes (e.g., southeastern US) are higher compared to marsh pools at high latitudes (e.g., east coast of Canada). A more comprehensive understanding of the role of marsh pools in the life history of nekton would be useful for conserving, managing, and restoring salt marshes and the species found in these environments.

Preliminary Insight into Winter Native Fish Assemblages in Guadiana Estuary Salt Marshes Coping with Environmental Variability and Non-Indigenous Fish Introduction

This work aims to undertake a preliminary characterization of winter fish assemblages in the salt marsh areas of Guadiana lower estuary (South-East Portugal) and discusses the potential risks of habitat dominance by a non-indigenous species (NIS). To this effect, six field campaigns were carried out in four sampling sites during winter season targeting the collection of fish species. A total of 48 samples were collected. Individuals from seven different taxa (marine and estuarine) were collected, although the assemblage was dominated by two estuarine species—the native Pomatoschistus sp. (goby) and the NIS Fundulus heteroclitus (mummichog). Goby was the most abundant taxa in the majority of salt marsh habitats, except for one specific, marsh pool, where extreme environmental conditions were registered, namely high temperature and salinity. Such conditions may have boosted the intrusion of mummichog in this area. This species is well adapted to a wide range of abiotic factors enabling them to colonize habitats where no predators inhabit. Impacts of mummichog introduction in the Guadiana salt marsh area are still unpredictable since this is the first time they have been recorded in such high density. Nevertheless, in scenarios of increased anthropogenic pressure and, consequently, habitat degradation, there is a potential risk of mummichog spreading to other habitats and therefore competing for space and food resources with native species.

Recruitment and Habitat Use of Early Life Stage Tarpon (Megalops atlanticus) in South Carolina Estuaries

Our study was designed to examine early life stage tarpon (Megalops atlanticus) recruitment, habitat use, and residency in coastal environments near the northern limit of their distribution in the western Atlantic Ocean. We employed a multi-faceted approach to (1) collect ingressing larval tarpon on nighttime flood tides at multiple sites, (2) document larval and juvenile tarpon use of natural high marsh pools, and (3) examine juvenile tarpon movement and behavior in managed marsh impoundments, all in the North Inlet-Winyah Bay estuarine system of South Carolina, USA. The timing of recruitment (June through November) and size of larvae (mean ± standard deviation = 23 ± 3 mm standard length [SL]) during estuarine ingress was similar to that reported from other subtropical locations in the region. Soon after recruiting into the system, larval and small juvenile tarpon (47 ± 25 mm SL) co-occurred in high marsh pools from July to November, and large juveniles (201 ± 34 mm SL) were also present in marsh impoundments during this same time period. An increase in tarpon length over time during their residency in high marsh pools and the relatively large size they attain in marsh impoundments indicate these environments may function as favorable nursery habitats. As water temperatures decreased during October and November, juvenile tarpon emigrated from these estuarine habitats. Tarpon appear to use a variety of estuarine habitats in coastal South Carolina from summer through late fall during their early life stage development. The fate of these individuals after they leave estuarine habitats at the onset of winter in this region is currently unknown.

Are Salt Marsh Pools Suitable Sites for Restoration? by Joseph Smith and Larry Niles

Tidal marsh function and ecological integrity are influenced by an array of direct and indirect stressors. At the same time these marshes are responding to accelerated sea level rise. Alone or in interaction these stressors can contribute to marsh degradation and potentially reduce the resilience of marshes to sea level rise. Agencies and conservation organizations have acknowledged both the importance of marshes and the threat they face through the conservation and protection of marshes and, more recently, by investing in restoration.

Diversity of foraminifera in a shallow restricted lagoon in Bahrain

We document the foraminiferal diversity across a semi-enclosed pool in eastern Bahrain that we named “Murray’s Pool†because this is the same location as the one studied by Basson and Murray (1995), the only previous study of foraminifera in this sector of the Arabian Gulf. We subdivided the sampling area into six subenvironments based on distinguishable physical environmental features, namely tidal channel, tidal flat, Salicornia marsh, algal mat, sheltered inner lagoon, and back marsh pool. Faunal analysis from these six shallow-water subenvironments reveals two main assemblages of benthic foraminifera: an Ammonia convexa-Elphidium advenum-Peneroplis pertusus assemblage and an Ammonia convexa-Coscinospira hemprichii-Peneroplis pertusus assemblage. The most abundant species across all the subenvironments are Peneroplis pertusus, Ammonia convexa, Coscinospira hemprichii, and Elphidium advenum. Species assemblage composition and percentage abundances were determined for each subenvironment; the tidal flat subenvironment shows the highest total abundance, but has twenty-four fewer species compared to the sheltered inner lagoon. We also noted the proportions of living foraminifera and juveniles in all the subenvironments to understand the distribution of biofacies within the lagoon. The numbers of juvenile miliolid foraminifera are highest in the tidal channel and the two adjacent subenvironments of the tidal channel.

Fish Productivity and Trophic Transfer in Created and Naturally Occurring Salt Marsh Habitat

High marsh pools are natural features in New England salt marshes that provide important subtidal refuge for the dominant resident fish, Fundulus heteroclitus (mummichog). F. heteroclitus is considered an important component in the trophic transfer pathway for its omnivorous diet and role as a prey species providing connectivity to adjacent near-shore and terrestrial habitats. Pool creation, such as ditch-plugging, is a common component of habitat restoration and enhancement projects throughout the region. Our study combined field experiments measuring fish growth and benthic invertebrates with carbon and nitrogen stable isotopes measurements to test the hypothesis that ditch plug pools have similar trophic structure and levels of productivity as naturally occurring salt marsh pools. Marked fish placed in enclosures were measured for length and weight weekly in natural pools and pools created using ditch plugs. Benthic invertebrates were sieved and sorted from soil cores to characterize invertebrate community structure, and stable isotopes were used to posit diets and trophic pathways associated with each pool type. Growth in fish length was 27 % higher and instantaneous biomass growth 17 % higher in natural pool habitat than in ditch plug habitat. Likewise, invertebrate species richness, biomass, and caloric value were all significantly greater in natural pool habitat than in ditch plugs. Stable isotope mixing models identified distinct resource utilization and trophic structure for natural and created pools. We attribute these differences to flooding and plant loss in response to ditch-plugging, which reduces habitat quality (as measured by resource availability, community structure, and trophic transfer) for fish and invertebrates. Our study increases our understanding of the ecology of salt marsh pools, and the significant results indicate that pools created using ditch plugs do not replicate the structure and function of natural pools at Moody Marsh.

Tidal and diel variations in abundance and schooling behavior of estuarine fish within an intertidal salt marsh pool

Tidally driven fluctuations lead to rapid variations in hydrological properties that can have profound effects on the dynamic and functions of salt marshes. During low tides, many nektonic species find refuge from predatory fish in shallow intertidal pools. The utilization of shallow pool refuges also exposes fishes to fitness costs that fluctuate between day and night. Yet, how aggregated fish using an intertidal pool modulate their schooling behavior over the diel cycle remains unknown. Using high-resolution imaging sonar (ARIS), we monitored an intertidal pool over a 3-day period and quantified fish abundance, size, and schooling behavior relative to the diel and tidal cycles. Higher fish abundance was found during low tides than high tides when the section was connected with the subtidal waters. At low tide, no differences in fish abundance and size were detected in the pool between day and night, but larger schools formed at night than day. Our results suggest that biotic and abiotic factors affecting fish schooling behavior in the low tide refuge may vary over the diel cycle. We present possible functional explanations for the shifts in schooling tendency between nocturnal and diurnal utilization of the pool.

Connectivity Among Salt Marsh Subhabitats: Residency and Movements of the Mummichog (Fundulus heteroclitus)

We examined connectivity among marsh subhabitats to determine the structural limits and important components of a polyhaline salt marsh by studying the patterns of abundance, residency, and movement of a numerically and ecologically dominant nektonic fish (mummichog, Fundulus heteroclitus). We captured, tagged (n = 14,040 individuals, 30–110 mm), and recaptured from Feb 2001 to Jul 2002, although most recaptures (75–95% by tagging location) occurred within 150 days. Seasonal residency and movements were common among most subhabitats based on catch per unit effort and recapture per unit effort. Thus, these (marsh pools, intertidal and subtidal creeks, and marsh surface) should be considered natural subhabitats within New England type salt marshes. Further, all these subhabitat types should be included in studies of salt marsh nekton and marsh restoration and creation activities.

Dactylobiotus luci, a new freshwater tardigrade (Eutardigrada: Macrobiotidae) from theRwenzori Mountains, Uganda

A new freshwater eutardigrade, Dactylobiotus luci is described from a permanent marsh pool (Zaphania’s Pool) at 4225 m elevation in the Alpine zone of the Rwenzori Mountains, Uganda. The new species is most similar to D. dervizi Biserov, 1998 in the shape of the egg processes, absence of papillae and absence of eyes, but differs from it mainly by a different appearance of macroplacoids, by having tips of the egg processes usually sharp, not divided and more slender, and by several morphometric characters of eggs and adults. The new species was found in fairly acidic (pH < 6) Sphagnum-Carex fens bordering/extending into the pool. So far, it has only been recorded in one other high-elevation water body in Rwenzori in a similar habitat.

Habitat heterogeneity: importance of salt marsh pools and high marsh surfaces to fish production in two Gulf of Maine salt marshes

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 368:217-230 (2008) - DOI: https://doi.org/10.3354/meps07560 Habitat heterogeneity: importance of salt marsh pools and high marsh surfaces to fish production in two Gulf of Maine salt marshes Richard A. MacKenzie1,2,*, Michele Dionne1 1Wells National Estuarine Research Reserve, 342 Laudholm Farm Rd., Wells, Maine 04090, USA 2USDA Forest Service Institute of Pacific Islands Forestry, 60 Nowelo St., Hilo, Hawai’i 96720, USA *Email: rmackenzie@fs.fed.us ABSTRACT: Both permanent high marsh pools and the intertidal surfaces of Spartina patens high marshes in southern Maine, USA, proved to be important habitat for resident mummichog Fundulus heteroclitus production. Manipulations of fish movement onto high marsh surfaces revealed similar growth rates and production among fish that were (1) restricted to pools, (2) had access to known areas of marsh surface, or (3) had free access to the entire marsh. Smaller scale manipulations with marked fish revealed that males with access to the marsh surface accumulated significantly more biomass, often exhibited higher growth rates, and had a 1.6× greater production rate than males restricted to pools. Female production was only slightly higher for fish that could access the marsh compared to fish restricted to pools. While both pools and marsh surface appeared to support fish production, habitat partitioning also existed between sexes of mummichogs; males may rely more on the marsh surface for food while females rely more on pools. Growth and production of mummichogs in pools on the high marsh surface was lower than values reported from more southern, low marsh dominated systems. This was attributed to differences in (1) abiotic factors of salt marsh pools (this study) and tidal creeks and channels (other studies), (2) climate, and (3) tidal inundation and access time to the marsh surface. Fish production on the surface of Gulf of Maine high marsh ecosystems was equivalent to production in adjacent tidal creeks and channels. Thus, the high marsh surface proved to be an important habitat for supporting fish production in this region. KEY WORDS: Secondary production · High salt marsh · Gulf of Maine · Fundulus heteroclitus Full text in pdf format PreviousNextCite this article as: MacKenzie RA, Dionne M (2008) Habitat heterogeneity: importance of salt marsh pools and high marsh surfaces to fish production in two Gulf of Maine salt marshes. Mar Ecol Prog Ser 368:217-230. https://doi.org/10.3354/meps07560 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 368. Online publication date: September 25, 2008 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2008 Inter-Research.

Palaeoenvironmental Reconstruction from Sediments at West Quay Road, Southampton

This detailed study of a 13m deep borehole from West Quay Road, Southampton documents estuary evolution over the Holocene in a locality which has received little attention in the literature. The work was undertaken by the Museum of London Archaeology Service Geoarchaeology department. The sediment sequence along with evidence from pollen, plant macrofossils, diatoms, ostracods, snails and radiocarbon dating shows the gradual drowning of the valley from the Lateglacial to the historic period. The evidence shows shifts in floral and faunal communities as coastal and estuarine habitats encroach inland with sea-level rise. Thick fen carr peat developed from the early Mesolithic over river terrace gravels and freshwater channels, while Boreal forest thrived in the surroundings. As tidal environments became more influential, a mosaic of reed beds and salt marsh pools developed by the late Mesolithic. A period of estuary contraction is indicated by the growth of freshwater sedge fen around the early to mid Neolithic, followed by clear marine transgression and persistence of estuarine mudflat environments into the historic period. The work supports the three phase model of Holocene estuary development of Long et al. (2000) which concluded that regional processes control estuary evolution. Although small-scale, this project contributes to the wider palaeogeographic and palaeoenvironmental picture within the Solent, and initiatives such as this form the backdrop for archaeological studies in the region. The length of the sedimentary archive and the amount of information gained show the value of geoarchaeological boreholes undertaken as part of developer-funded projects.

Dactylobiotus luci, a new freshwater tardigrade (Eutardigrada: Macrobiotidae) from the Rwenzori Mountains, Uganda

A new freshwater eutardigrade, Dactylobiotus luci sp. nov., is described from a permanent marsh pool (Zaphania's Pool) at 4225 m elevation in the Alpine zone of the Rwenzori Mountains, Uganda. The new species is most similar to D. dervizi Biserov, 1998 in the shape of the egg processes, absence of papillae and absence of eyes, but differs from it mainly by a different appearance of macroplacoids, by having tips of the egg processes usually sharp, not divided and more slender, and by several morphometric characters of eggs and adults. The new species was found in fairly acidic (pH < 6) Sphagnum-Carex fens bordering/extending into the pool. So far, it has only been recorded in one other high-elevation water body in Rwenzori in a similar habitat.

Global population genetic structure of the starlet anemone Nematostella vectensis: multiple introductions and implications for conservation policy

Distinguishing natural versus anthropogenic dispersal of organisms is essential for determining the native range of a species and implementing an effective conservation strategy. For cryptogenic species with limited historical records, molecular data can help to identify introductions. Nematostella vectensis is a small, burrowing estuarine sea anemone found in tidally restricted salt marsh pools. This species’ current distribution extends over three coast lines: (i) the Atlantic coast of North America from Nova Scotia to Georgia, (ii) the Pacific coast of North America from Washington to central California, and (iii) the southeast coast of England. The 1996 IUCN Red List designates N. vectensis as “vulnerable” in England. Amplified fragment length polymorphism (AFLP) fingerprinting of 516 individuals from 24 N. vectensis populations throughout its range and mtDNA sequencing of a subsample of these individuals strongly suggest that anthropogenic dispersal has played a significant role in its current distribution. Certain western Atlantic populations of N. vectensis exhibit greater genetic similarity to Pacific populations or English populations than to other western Atlantic populations. At the same time, F-statistics showing high degrees of genetic differentiation between geographically proximate populations support a low likelihood for natural dispersal between salt marshes. Furthermore, the western Atlantic harbors greater genetic diversity than either England or the eastern Pacific. Collectively, these data clearly imply that N. vectensis is native to the Atlantic coast of North America and that populations along the Pacific coast and in England are cases of successful introduction.

Fish Composition and Abundance in New Jersey Salt Marsh Pools: Sampling Technique Effects

Unaltered salt marsh pools in southern New Jersey were sampled during the summer over a number of years, with a variety of techniques, to compare fish species and size composition relative to sampling gear type and to enhance our understanding of marsh pool fishes. These pools were dominated by a few species (Fundulus heteroclitus, Cyprinodon variegatus, Menidia beryllina, Lucania parva, and M. menidia made up 98.3% of all fish [n = 33,731] collected). However, species composition clearly varied with sampling technique, with some species common in multiple gears, e.g., F. heteroclitus in quatrefoil traps (38.6% of total number) and wire mesh traps (35.5%), and C. variegatus collected in quatrefoil traps (47.6%) and mini-seine (30.9%). Other species were most abundant in selected gears, e.g., M. beryllina (83.8%), L. parva (72.6%), and M. menidia (99.6%) in quatrefoil traps. Size composition, which included young-of-the-year and adults for most species, varied with sampling technique and species as well. In all of the above, we cannot rule out the possibility that annual variation influenced species composition and abundance; however, given the stability of these measures in other informal observations, we are convinced that most of the variation is due to sampling technique. Continued studies are relevant because marsh pools have been eliminated by a variety of practices, but are also being created as the result of some mosquito-control techniques and for restoration purposes.