DOI•
Effects of habitat quality on secondary production in shallow estuarine waters and the consequences for the benthic-pelagic food web
01 Jan 2010-
TL;DR: In this article, the authors discuss the impact of habitat degradation on second-person production in the Saline Estuary and the Tidal Freshwater watershed in the state of Illinois.
Abstract: ................................................................................................................... ix CHAPTER I. ASSESSMENT OF HABITAT DEGRADATION IN THE COASTAL ZONE AND THE CONSEQUENCES FOR RESIDENT BlOT A .................................. .2 Introduction .............................................................................................................. 3 Motivations and Investigative Approach ............................................................... 12 Literature Cited ...................................................................................................... 15 CHAPTER II. THE INFLUENCE OF HABIT AT QUALITY ON SECONDARY PRODUCTION IN SHALLOW ESTUARINE WATERS ............................................ 28 Abstract .................................................................................................................. 29 Introduction ............................................................................................................ 30 Materials and Methods ........................................................................................... 33 Site Selection ................................................................................................... 33 Data Collection ..................................................................... , .......................... 34 Analysis ............................................................................................................ 37 Results .................................................................................................................... 39 Discussion .............................................................................................................. 41 Interpreting the Saline Estuary ........................................................................ .42 Interpreting the Tidal Freshwater .................................................................... .46 Some Comments on Biodiversity and Productivity ........................................ .47 Conclusions ............................................................................................................ 49 Literature Cited ...................................................................................................... 50 CHAPTER Ill. THE INFLUENCE OF HABIT AT QUALITY AND MACROBENTHIC COMMUNITY COMPOSITION ON NEKTON UTILIZATION OF SECONDARY PRODUCTION AS A FOOD SOURCE ........................................................................ 68 Abstract .................................................................................................................. 69 Introduction ............................................................................................................ 70 Materials and Methods ........................................................................................... 74 Site Selection ................................................................................................... 7 4 Data Collection ................................................................................................ 74 Analysis ............................................................................................................ 77 Results .................................................................................................................... 80 Site Characterization ........................................................................................ 80
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Journal Article•
TL;DR: In this article, the stable isotope compositions (C, N, and S) of hve, senescent, and standing dead Spartina alterniflora were compared in order to determine the effects of aerial decomposition on the isotopic signature of aboveground S. alternjflora entering the food chain, which indicated that N2fixing microorganisms associdated with microalgal communities were an important source of N to salt marsh consumers.
Abstract: The stable isotope compositions (C, N, and S) of hve, senescent, and standing dead Spartina alterniflora were compared in order to determine the effects of aerial decomposition on the isotopic signature of aboveground S. dlterniflora tissue entering the food chain. Aerial decomposition of aboveground S. alterniflora resulted in a 6 to 18% increase in P S , and a 2 to 3 % decrease in 615N values; 613c values were unchanged. We describe mechanisms whereby the activity of fungi and epiphytic microorganisms may contribute to the observed shlfts in and 6I5N, respectively. The 613c value of salt marsh benthic and eplphytic microalgae ranged from -13.0% in summer to -17.6%0 in early spring. Average 6'\" values of microalgae and standing dead S. altemiflora were -0 3 and l.?%, respectively, reflecting the activity of NZ-fixing microorganisms. The 615N values for omnivorous and herbivorous salt marsh macrofauna ranged between 7.5 and 2.2% and for predatory Fundulus spp. averaged 9.2%. Given a presumptive + 3 % trophic shift in N assimilation, these results suggest that N2-fixing microorganisms associdted with microalgal communities were an important source of N to salt marsh consumers. The 6% 6'\"N, and 6\"'s values of primary producers were compared to the values of the following consumers: Fundulus spp., Uca spp., Ilyanassa obsoleta, and Littoraria irrorata. 6I3C VS 6 1 5 ~ and 613C vs 63JS dual isotope plots demonstrated that microalgae and standing dead S. alternjflora are important food resources in the North Carolina (USA) marshes we sampled. In addition, a compilation of literature values suggests that this is true in salt marshes throughout the East and Gulf coasts of North America. Future isotope studies of marsh food webs should include detrital Spartina spp. material in analyses of trophic structure.
9 citations
TL;DR: The ecological analysis showed that total phosphorus concentration, temperature and salinity were the main environmental parameters affecting community structure of the Parila lagoon, and six species listed as frequent have a potential to be used as indicators of habitat quality.
Abstract: The aim of the study was to describe epibenthic macroinvertebrates and demersal fish and to identify links between spatial patterns and habitat characteristics (sediment, salinity, oxygen and temperature). The research was performed in the Parila lagoon in Croatia; an important nursery ground where conditions in epibenthic community can have significant direct and indirect impact on fisheries. Diversity (30 species) and abundance (from 0 to 7 ind m−2) of epibenthic assemblages was low on all stations and showed remarkable seasonal changes. Such patchiness could support the estuarine quality paradox idea, i.e. the most abundant species are well adapted to changing conditions in a variable environment. The ecological analysis showed that total phosphorus concentration (TP), temperature (T) and salinity (S) were the main environmental parameters affecting community structure of the Parila lagoon. Six species listed as frequent (Nerophis ophidion, Zosterisessor ophiocephalus, Syngnathus typhle, Cerastoderma glaucum, Palaemon adspersus and Carcinus aestuarii) have a potential to be used as indicators of habitat quality. In terms of trophic diversity, community was dominated by carnivores and omnivores. Fish trophic index (above 2.7) indicated upward shift of the local food chain and towards mostly carnivorous species, while the absence of herbivorous species pointed to low environmental quality. The present study gives an insight into the current ecological conditions in the Parila lagoon. Further research about the sensitivity of these potential indicators to different types of pressure is necessary in order to select robust early-warning indicators framework.
4 citations
Cites background from "Effects of habitat quality on secon..."
...and economically important nekton that use such habitat during their lifecycle as nurseries (Gillet 2010)....
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...…ecological measurement of environmental disturbances that reflects in the ecological functioning, which in turn will be realized throughout the ecosystem via shifts in trophic relationships, nutrient cycling, and other key processes, and eventually provisioning of ecosystem services (Gillet 2010)....
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...In estuarine food webs, they represent a link between highly productive organic matter sources of the shallows and ecologically and economically important nekton that use such habitat during their lifecycle as nurseries (Gillet 2010)....
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...throughout the ecosystem via shifts in trophic relationships, nutrient cycling, and other key processes, and eventually provisioning of ecosystem services (Gillet 2010)....
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...real relationships in the ecosystem (Gillet 2010)....
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References
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TL;DR: It is concluded that BMI were a significant component of the food web supporting F. heteroclitus feeding habits in these brackish marshes, and a conclusion consistent with the reduced BMI biomass found inPhragmites marshes.
Abstract: The invasion ofPhragmites australis into tidal marshes formerly dominated bySpartina alterniflora has resulted in considerable interest in the consequences of this invasion for the ecological functions of marsh habitat. We examined the provision of trophic support for a resident marsh fish,Fundulus heteroclitus, in marshes dominated byP. australis, byS. alterniflora, and in restored marshes, using multiple stable isotope analysis. We first evaluated our ability to distinguish among potential primary producers using the multiple stable isotope approach. Within a tidal creek system we found significant marsh and elevation effects on microalgal isotope values, and sufficient variability and overlap in primary producer isotope values to create some difficulty in identifying unique end members. The food webs supportingF. heteroclitus production were examined using dual isotope plots. At both sites, the δ13C values ofF. heteroclitus were clustered over values for benthic microalgae (BMI) and approximately midway between δ13C values ofSpartina andPhragmites. Based on comparisons of fish and primary producer δ13C, δ15N, and δ34S values, and consideration ofF. heteroclitus feeding habits, we conclude that BMI were a significant component of the food web supportingF. heteroclitus in these brackish marshes, especially recently-hatched fish occupying pools on the marsh surface. A 2‰ difference in δ13C betweenFundulus occupying nearly adjacentSpartina andPhragmites marshes may be indicative of relatively less reliance on BMI and greater reliance onPhragmites production inPhragmites-dominated marshes, a conclusion consistent with the reduced BMI biomass found inPhragmites marshes. The mean δ13C value ofF. heteroclitus from restored marshes was intermediate between values of fish from naturally occurringSpartina marshes and areas invaded byPhragmites. We also examined the isotopic evidence for ontogenetic changes in the trophic position of larval and juvenileF. heteroclitus. We found significant positive relationships betweenF. heteroclitus δ15N values and total length, reflective of an increase in trophic position as fish grow.F. heteroclitus δ15N values indicate that these fish are feeding approximately two trophic levels above primary producers.
102 citations
TL;DR: Overall, infauna in this system relied on phytoplankton and benthic algae as dominant food resources, and dietary contributions from primary producers varied among species and habitats.
Abstract: Despite the paradigm that Spartina spp. detritus is the basis for estuarine food webs, other primary producers may contribute to the diets of saltmarsh consumers. To determine the dietary contribution of primary producers to benthic infauna in the Plum Island Estuary, Massachusetts, USA, we examined natural abundance stable isotopes in 4 intertidal saltmarsh habitats and conducted an 15 N enrichment experiment in 2 habitats. Natural abundance isotope data suggested that Spartina spp. detritus was of limited dietary importance to infauna in all habitats (including Spartina spp. understory) and instead benthic algae and phytoplankton were the dominant food sources. 15 N enrichment was used to improve dietary resolution of benthic algae and phytoplankton sources that had similar natural abundance values. To label only benthic algae, 15 N-enriched Na 15 NO3 was applied daily for 14 d to sediment in mudflat and creek-wall habitats. Food-web incorporation of 15 N-labeled benthic algae was found in most species. However, label uptake in the polychaetes Man- ayunkia aestuarina, Fabricia sabella and Streblospio benedicti indicated that phytoplankton was the most important food source for these consumers. Label uptake in the polychaete Nereis diversicolor differed between habitats, suggesting a large dietary contribution of microphytobenthos (MPB) in mudflat and phytoplankton in creek wall. The oligochaete Paranais litoralis consumed both MPB and phytoplankton regardless of habitat. The harpacticoid copepod Heterolaophonte sp. consumed pri- marily epiphytic diatoms. Overall, infauna in this system relied on phytoplankton and benthic algae as dominant food resources, and dietary contributions from primary producers varied among species and habitats.
100 citations
TL;DR: In this article, the sources and diagenesis of sedimentary organic material were studied by means of stable C and N isotopes and gas chromatography of pyrolysates from plants, suspended sediments, and a series of muds from St Catherines Island, Georgia.
Abstract: Organic matter preserved in sediments of Georgia salt marshes derives from Spartina alterniflora and planktonic and bacterial substances. Sources and diagenesis of sedimentary organic material were studied by means of stable C and N isotopes and gas chromatography of pyrolysates from plants, suspended sediments, and a series of muds (modern to 1400 years old) from St Catherines Island, Georgia. Suspended particulate matter ( > 20 μm) has isotopic compositions (δ 13 C = −18 to −22), which are composed of an average 34–42% plankton carbon and 58–65% higher plant detritus, as determined by isotopic mass balance of the system. The δ 13 C of bulk sediments and humic acids (δ 13 C = −18 to −19) extracted from them remain relatively constant over time. The δ 13 C of acid hydrolysates, however, changed from − 15‰ in surface marsh sediment to a δ 13 C of −19 from sediment sampled at a depth of 125 cm. Higher-plant normal-hydrocarbons are present in muds and in particulate matter from the water column, and δ 13 C in lipids and gas chromatography of pyrolysates of samples reflect this addition. With increasing age, δ 15 N of total sediments and acid hydrolysates increases, and the ratio of odd-to-even hydrocarbons in the pyrolysates decreases. Initially, low density material in sediments consists primarily of plant fragments. With time, this material is decayed and diluted by microbial material, changes that are reflected by more negative δ 13 C of −15 to −17·5, as compared to δ 13 C of −12 for moden Spartina , and the addition of n-alkanes in the range of C 13–19 . The isotopic heterogeneity in surface sediments with carbon as an example, ranged from a δ 13 C of −15 (plant fragments) to −22 (sediment following lipid, humic acid, and plant fragment extraction). Nowhere was the C isotopic composition of total Spartina expressed even though microscopic plant pieces, lignocellulose pyrolysis fragments, and n-alkanes from C 22–27 were detected in suspended particulate matter, total sediments, and humic acids.
99 citations
Book•
26 Jul 2004
TL;DR: A bestseller for nearly 25 years, Analysis of Messy Data, Volume 1: Designed Experiments helps applied statisticians and researchers analyze the kinds of data sets encountered in the real world.
Abstract: A bestseller for nearly 25 years, Analysis of Messy Data, Volume 1: Designed Experiments helps applied statisticians and researchers analyze the kinds of data sets encountered in the real world. Written by two long-time researchers and professors, this second edition has been fully updated to reflect the many developments that have occurred since t
98 citations
TL;DR: In this paper, the authors consider both bioenergetic and landscape constraints on direct flows of marsh-derived produc- tion to populations of resident and migrant nekton, and find that there is a strong sigmoid relationship between fishery production and the amount of intertidal marsh/creek edge within a 200 m radius of a site.
Abstract: The connection between fishery production and vegetated intertidal habitats is often a key consideration in the rationale for protecting and restoring estuarine salt marshes. Evaluating the contribution of marsh habitats to estuarine nekton production requires an understanding of the mechanisms and constraints controlling production flows to nekton populations; this is especially important for setting and judging success criteria associated with restoration projects. This contribu- tion considers both bioenergetic and landscape constraints on direct flows of marsh-derived produc- tion to populations of resident and migrant nekton. Nekton access to marsh resources is defined in terms of trophic (bioenergetic) and physical (landscape) constraints that determine the amount of nekton production that can be expected. Production to biomass (P:B) ratios applied to measurements of nekton standing stock from multiple marsh sites around Sapelo Island, Georgia, USA provided an example of the spatial variation in nekton production that can be expected from natural marshes. When P:B ratios of 2, 5, and 3 were applied to standing stocks of fishes, caridean shrimps and penaeid shrimps, respectively, annual net production of nekton from 12 intertidal marsh sites ranged from 0.12 to 2.88 g dry weight (dw) m -2 and averaged ca. 1.50 g dw m -2 ; other scenarios using different sets of P:B ratios yielded production ranges of 0.11 to 2.25 and 0.17 to 4.57 g dw m -2 . There was a strong sigmoid relationship between nekton production and the amount of intertidal marsh/creek edge within a 200 m radius of a site for both resident and migrant species. Production was lowest at sites with relatively little marsh/creek edge, and increased rapidly with increasing drainage density until reaching an asymptote, after which even large changes in the amount of marsh/creek edge had no effect on nekton production. The findings suggest that bioenergetic constraints determine the ulti- mate capacity of intertidal marsh systems to produce nekton, but nekton production may be enhanced by relatively small additions of marsh/creek edge up to a threshold level above which no additional enhancement should be expected. Site-specific bioenergetic and landscape constraints should be considered when developing realistic expectations and success criteria for marsh restora- tion efforts aimed at enhancing estuarine nekton production.
93 citations