As with most methodologies, some of the most important assumptions in Network Analysis are made at the outset. They concern decisions as to what to choose as the primary elements of the network and how these taxa are to be connected. In this project, these decisions are simplified somewhat by the requirement that the network be comparable to the ATLSS simulation. That is, each state variable of the ATLSS model must have its counterpart in the accompanying network.

Network analysis, however, can treat far more complicated webs of interaction than are possible using simulation modeling. Keeping the simulation dynamics of many coupled processes from becoming pathological is a difficult balancing act. Because NA does not deal explicitly with dynamics, far greater taxonomic resolution becomes possible with this form of analysis. As a result, some taxa in the ATLSS model will be represented by several compartments in the graminoid network. In addition, compartments can be added to the network with relative ease. For example, the creation of an individual-based model for one of the lesser-known bird species (e.g. the swamp sparrow) would entail significant effort. As will be described below, it requires nowhere near as much work to include this compartment in the quantified trophic web.

Although the primary reason for creating these networks is to serve as a calibration benchmark for ATLSS, it should be mentioned that each single network and its ensuing analysis could also serve independent purposes. For example, some biologists will be curious to know how the particular species that they are interested in, which might not appear in ATLSS, will fare under the proposed hydrological scenarios. With regard to trophic interactions at least, the results of NA should allow those investigators and managers to make some educated guesses about how the excluded population might change. For example, NA quantifies the direct and indirect trophic interactions of each compartment with all other compartments in the web. In particular, the stocks and activities of each compartment that do not appear in ATLSS can be compared with all those that do participate through NA. Any coefficients and ratios as may result can be applied to the predicted outputs from ATLSS to estimate the accompanying trophic status of the non-included species. In other words, after calibration NA can serve to expand the scope of predictions from ATLSS.

From an ecological viewpoint, virtually all the important trophic components (i.e., those comprising at least 5% of the standing biomass or activity) have been written into ATLSS. These include detritus, microbes, aquatic macrophytes, mesoinvertebrates, macroinvertebrates, piscivorous fish, planktivorous fish, etc.

As for the previous three networks, the cypress wetland ecosystem, the Florida Bay ecosystem and the mangrove ecosystem, it happened that data did exist to make at least crude estimates of the stocks and activities of a number of some other ecosystems members. Similarly, it was decided to include these "parallel" species in the NA of the graminoid network.

In addition, in order to wind up with more homogeneous and comparable networks, the choices that were made in the three previous network models have been taken into consideration in drawing up the list of components for the graminoid ecosystem. Because many of the species that are resident in the mangroves and cypress systems feed in the graminoid marshes, there will be interactions between these systems, and some redundancies among their species. For example, most of the fishes and invertebrates listed for cypress system are present as well in the graminoids. The same goes for many of the mammals and birds in the cypress and the birds in the mangroves. Conversely, the estuarine and marine species of the mangrove and Florida Bay systems are not seen in the freshwater graminoid marshes. This results in a lower number of compartments in the graminoid ecosystem than comprised any of the preceding three systems. In deciding which elements to include in the network and how these taxa are to be connected, the same resolution was used as was employed with the previous three biotopes, in order that the elements and structure of the four different network models will remain comparable.

For some categories, such as invertebrates and fish, individual compartments for each of the more abundant and better-documented species have been reserved, while the remaining species were combined into single "other macroinvertebrates", "other small fish" and "other large fish" compartments.

In many networks the major lexical question involved how to treat the manifold species that comprise some functional groups for which data at the level of individual species were not available. To characterize these poorly resolved parts of the ecosystem, it was decided to group the species into generalized compartments. Such was the case in the graminoid network for mesoinvertebrates and passerine birds. The same aggregation has been done for bacteria and protozoans in the water column and sediments, which were assigned to a compartment called "living POC" and "living sediments", respectively.

The completed networks both consist of 66 separate components. Only those species closely associated with the dominant patterns have been retained. Hence, only those primary producers, invertebrates, fishes, reptiles, birds and mammals commonly found in the graminoid system made the final list of species. Once completed, the list was aggregated somewhat according to certain criteria, such as species sharing the same diet, available data and the goals of ATLSS. For example, most species to be included in ATLSS as individual-base models have been maintained as separate compartments in the network.

The following is the final list of components composing the graminoid ecosystem network, along with a very brief description of what each compartment entails:

The initial elements of the network are the living compartments of the microbial loop. They have been divided as follows:

1. LIVING SEDIMENTS. Includes all bacteria and fungi living at the sediment level.
2. LIVING POC. Bacteria and protozoans that occur in the water column are all represented in this compartment.
   

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3.B Primary producers

A description of the dominant primary producers is reported in the "study area" section of this report. They have been divided as follows:

3. PERIPHYTON. Mostly diatomaceous forms of algae.
4. MACROPHYTES. The macrophyte assemblage includes sawgrass (Cladium jamaicense), two species that coexist with sawgrass — Peltandra virginica and Pontederia cordata. Eleocharis spp. was most abundant within the wet prairie community, while Hymenocallis palmeri, Panicum hemitomon, and Sagittaria lancifolia, co-occur within the wet prairie community (Daoust & Childers, 1999).
5. UTRICULARIA. The vascular plants included in the floating mat consist of two species: Utricularia chara and Utricularia bacopa (not common). Utricularia is a carnivorous plant that generally occurs in nutrient-poor habitats that are sunny and moist (at least during the growing season), where they are often dominant (Givnish, 1989).
6. FLOATING VEGETATION. The floating vegetation includes all non-rooted plants, and a few that may or may not be rooted. Examples include as pond lilies and duckweed.

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3.C Invertebrates

As might be expected, the invertebrates of the Everglades graminoids are similar in species composition to those of the Cypress system. However, better data were available for the construction of the graminoid network, so that the invertebrate assemblage could be expanded in the newer graminoid model.

7. APPLE SNAIL. This compartment contains only Pomacea paludosa, the apple snail. Other snails are found in Aquatic Macroinvertebrates.
8. FRESHWATER PRAWN. Contains only the freshwater shrimp Palaemonetes paludosus.
9. CRAYFISH. The Everglades are populated almost exclusively by Procambarus alleni. There is some evidence, however, that another species, Procambarus clarkii, which has been introduced throughout Florida, may be present in some areas of the Everglades (Franz and Franz 1990).
10. MESOINVERTEBRATES. This is the first of four general invertebrate compartments. It contains small aquatic invertebrates, including animals from the following taxonomic groups: Oligochaeta, Bosminidae, Chydoridae, Daphniidae, Macrothricidae, Sididae, Calanoid and Harpacticoid copepods, Chironmidae. Fish larvae of comparable size are also included in this compartment.
11. OTHER MACROINVERTEBRATES. The second of the general invertebrate compartment contains all aquatic invertebrates larger than the mesoinvertebrates (just described) and smaller than the predatory aquatic insects. Representative animals from the following taxonomic groups: Trichoptera, Certaopogonidae, Tanypodinae, Gastropoda (excluding apple snails). Fish larvae of comparable size are also placed in this compartment because of their similar trophic stature.
12. LARGE AQUATIC INSECTS. All large predatory aquatic insects and larvae (e.g., dragonfly and damselfly nymphs) found in the graminoid marshes.
13. TERRESTRIAL INVERTEBRATES. This compartment contains all the invertebrates that are active in non-aquatic environments. There are very little quantitative data about these organisms, and the data here have been extrapolated from tropical grasslands outside the Everglades (Janzen and Schoener 1968). Organisms in this compartment will include adult forms of members of the aquatic invertebrates (Odonates, Ephemeroptera) and also any of the exclusively terrestrial insects (Lepidopterans, ants, wasps, etc.).
14. FISHING SPIDER. This compartment contains only the fishing spider, Dolomedes triton, because of its unique feeding habits (Jordan et al. 1994). The other spiders are found in the Terrestrial Invertebrates compartment.

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3.D Fishes

The fishes in the graminoids are generally the same species that were found in Cypress, however the fish assemblage in the Cypress was divided into only three compartments, small, herbivorous-omnivorous fish, small predatory fish and large, predatory fish. These assemblages could be separated in the graminoid marshes due to significantly more quantitative information available for this system.

15. GAR. A member of the family Lepisosteidae, Lepisoseus platyrhinchus, one of the top predatory fish species.
16. SHINERS AND MINNOWS. This compartment contains only the diminutive minnows of the family Cyprinidae, including such species as: golden shiner (Notemigonus chrysoleucas), tailight shiner (Notropis maculatus), coastal shiner (Notropis petersoni) and pugnose minnow (Opsopoedus emiliae)
17. CHUBSUCKERS. Lake chubsucker (Erimyzon succetta) is a member of the family Catastomidae.
18. CATFISH. Contains species from the family Ictaluridae and Clariidae. Typical species are: white catfish (Ameiurus catus), yellow bullhead (A. natalis), brown bullhead (A. nebulosus), channel catfish (Ictalurus punctatus) and tadpole madtom (Noturus gyrinus). The exotic walking catfish (Clarias batrachus) is the only representative from the family Clariidae.
19. FLAGFISH. One of the most abundant fishes in the Everglades, the flagfish (Jordanella floridae) is a member of the family Cyprinodontidae.
20. TOPMINNOWS. The topminnow species of the family Fundulidae. Included representatives are: Golden topminnow (Fundulus chrysotus), banded topminnow (F. cingulatus) and lined topminnow (F. lineolatus).
21. BLUEFIN KILLIFISH. One member of the family Fundulidae, the bluefin killifish (Lucania goodei), has been given its own compartment, because it is so abundant.
22. KILLIFISHES. This compartment contains the remaining species of family Fundulidae, such as the Seminole killifish (Fundulus seminolis) and the marsh killifish (F. confluentus).
23. MOSQUITOFISHES. Consists of only the Poecilid species, Gambusia affinis. The mosquitofish is another highly abundant small fish species.
24. POECILIDS. Contains the remaining Poecilds, including the very abundant species least killifish (Heterandria formosa) and sailfin molly (Poecilla latipinna). It also contains an introduced Poecilid species, the pike killifish (Belonesox belizanus).
25. PYGMY SUNFISH. The Centrarchids (sunfishes) have been split into as many single species compartments as possible, due both to their diverse feeding habits and to the large proportion of total fish biomass that they comprise. This compartment is devoted to the Everglades Pygmy Sunfish (Elasoma evergladei).
26. BLUESPOTTED SUNFISH. Enneacanthus gloriosus is one of the smaller Centrarchid species.
27. WARMOUTH. The warmouth (Lepomis gulosus) is one of the larger predatory species of sunfish in the Everglades.
28. DOLLAR SUNFISH. Lepomis marginatus.
29. REDEAR SUNFISH. The redear sunfish (Lepomis microlophus) consumes primarily gastropods.
30. SPOTTED SUNFISH. Lepomis punctatus.
31. OTHER CENTRARCHIDS. Contains any previously unmentioned Centrarchid, most notably the bluegill (Lepomis macrochirus) and the black crappie (Pomoxis nigromaculatus).
32. LARGEMOUTH BASS. Micropterus salmoides is one of the top predator fishes.
33. CICHLIDS. This compartment contains the assemblage of introduced Cichlids: Oscar (Astronotus oscellatus), peacock cichlid (Cichla ocellaris), black acaria (Cichlasoma bimaculatum) mayan cichlid (Cichlasoma uropthalmus), blue tilapia (Tilapia aurea), and spotted tilapia (Tilapia mariae).
34. OTHER LARGE FISHES. This is the first of two generic fish compartments and contains the rarer large freshwater fish of the Everglades as well as those euryhaline species that sometimes invade the freshwaters. Included are: Bowfin (Amia calva), American eel (Anguilla rostrata), pickerels (Esox spp.) shads (Dorosoma spp.), mullets (Mugil spp.) and snooks (Centropomis spp.)
35. OTHER SMALL FISHES. This is the second of two generic fish compartments and contains the rarer small freshwater fish of the Everglades as well as those euryhaline species that are known to invade freshwaters at various times of the year. Included are Silversides (Menidia spp.), gobies (Gobiosoma spp. and Microgobius spp.) and swamp darter (Etheostoma fusiforme).
    

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3.E Reptiles and Amphibians

Although not composed of exactly the same species, the list of reptile compartments resembles that of the cypress ecosystem. Reptiles have been divided into four separate compartments: snakes, lizard, turtles and alligators, most consisting of several species, with the exception of one single- species taxon, devoted to the American alligator (Alligator mississippiensis). Amphibians were divided into six separate compartments: salamanders, salamander larvae, large frogs, medium frogs, small frogs and tadpoles (Diffendorfer, et al. 1999).

36. SALAMANDERS. The salamander compartment includes the dwarf and greater sirens (Pseudobranchus striatus and Siren lacertina), the two-toed amphiuma (Amphiuma means) and the pensinsula newt (Notophthalmus viridescens) (Diffendorfer, et al. 1999).
37. SALAMANDER LARVAE. The larvae of all salamander species present in the graminoids are lumped here.
38. LARGE FROGS. Only one species of large frog is found in the graminoids: the pig frog (Rana grylio) (Diffendorfer, et al. 1999).
39. MEDIUM FROGS. Medium frogs include the southern toad (Bufo terrestris), green treefrog (Hyla cinerea), Cuban treefrog (Osteopilus septentrionalis), Florida chorus frog (Pseudacris nigrita), southern cricket frog (Acris gryllus), squirrel treefrog (Hyla squirella) and southern leopard frog (Rana sphenocephala) (Diffendorfer, et al. 1999).
40. SMALL FROGS. Small frogs include the oak toad (Bufo quercicus), eastern narrowmouth toad (Gastrophryne carolinensis), greenhouse frog (Eleutherodactylus planirostris) and the little grass frog (Limnaoedus ocularis) (Diffendorfer, et al. 1999).
41. TADPOLES. The tadpoles of all the frogs in the graminoids are gathered into this compartment.
42. TURTLES. Turtles include the common musk turtle (Sternotherus odoratus), striped mud turtle (Kinosternon baurii), eastern mud turtle (K. subrubrum subrubrum), Florida box turtle (Terrapene carolina bauri), chicken turtle (Deirochelys reticularia), peninsula cooter (Pseudemys floridana), Florida redbelly turtle (P. nelsoni), red ear slider (P.scripta), Florida snapping turtle (Chelydra serpentina) and the Florida softshell turtle (Apalone ferox) (Diffendorfer, et al. 1999).
43. SNAKES. Snakes found in the graminoids include: the Florida water snake (Nerodia fasciata), Florida green water snake (N. floridana), brown water snake (N. taxispilota), striped crayfish snake (Regina alleni), Florida brown snake (Storeria dekayi victa), black swamp snake (Seminatrix pygaea), eastern garter snake (Thamnophis sirtalis), peninsula ribbon snake (Thamnophis sauritus), southern ringneck snake (Diadophis punctatus), rough green snake (Opheodrys aetivus), mud snake (Farancia abacura), black racer (Coluber constrictor), eastern indigo snake(Drymarchon corais couperi), red rat snake (Elaphe guttata), yellow rat snake (E. obsoleta), Florida kingsnake (Lampropeltis getulus floridana), scarlet kingsnake (L. triangulum elapsoides), scarlet snake (Cemophora coccinea), cottonmouth (Agkistrodon piscivorus), dusky pygmy rattlesnake (Sistrurus miliarius barbouri) and eastern diamondback rattlesnake (Crotalus adamenteus) (Diffendorfer, et al, 1999).
44. LIZARDS. Lizards in the graminoid Everglades include the brown anole (Anolis sagrei), green anole (A. carolinensis), ground skink (Scincella laterale), island glass lizard (Ophisaurus compressus) and the five-lined skink (Eumeces inexpectatus) (Diffendorfer, et al. 1999).
45. ALLIGATORS. The American alligator (Alligator mississippiensis).
    
    

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3.F Mammals

Mammals in the graminoids show considerable overlap with those listed in the cypress wetland network.

46. MUSKRAT. Colonies of muskrat (Neofiber alleni) are abundant throughout the Shark River Slough and the open glades of the ENP (Tilmant, 1975).
47. MICE AND RATS. Species found in the graminoids include the cotton mice (Peromyscus gossypinus), cotton rats (Sigmodon hispidus), rice rats (Oryzomys palustris) and the exotic house mouse (Mus musculus).
48. RABBITS. The marsh rabbit (Silvilagus paulstris).
49. RACCOONS. Raccoons (Procyon lotor) are very abundant in the graminoid wetlands.
50. OPOSSUMS. The Virginia opossum (Didelphis virginiana).
51. OTTER. The river otter (Lutra canadensis).
52. MINK. The mink (Mustela vison).
53. DEER. The white-tailed deer (Odocoileus virginianus).
54. BOBCAT. Lynx rufus.
55. PANTHER. The Florida panther (Felis concolor).
    

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3.G Birds

Taxonomy, feeding habits and the availability of information were primary concerns in establishing the final list of birds. Species of birds that feed in the graminoids, but do not roost there, were not included, as they have already been accounted for in the cypress and mangrove models. Therefore, the compartments given in this model are mostly those not found in the other models. For lists of all species to be found in the graminoid Everglades, see Stevenson and Anderson (1994).

56. GREBES. Only one species of grebe is found in the graminoids, the pied-billed grebe (Podilymbus podiceps).
57. BITTERNS. One species of bittern breeds in the graminoids, the least bittern (Ixobrychus exilis).
58. DUCKS. Eight species of Anseriformes breed or roost in the graminoids: fulvous whistling duck (Dendrocygna bicolor), green-winged teal (Anas crecca), mottled duck (Anas fulvigula), mallard (Anas platyrhynchos), blue winged teal (Anas discors), northern shoveler (Anas clypeata), ring necked ducks (Aythya collaris) and the ruddy duck (Oxyura jamaicensis) (Stevenson and Anderson, 1994).
59. SNAILKITES. The snail kite (Rostrhamus sociabilis) is the most important species of Accipitridae in this system.
60. NIGHTHAWK. Only one species of Caprimulgiformes roosts or breeds in the graminoids, the common nighthawk (Chordeiles minor).
61. GRUIFORMES. Including the American coot (Fulica americana), limpkin (Aramus guarauna), king rail (Rallus elegans), common moorhen (Gallinula chloropus) and Sandhill crane (Grus canadensis pratensis) (Stevenson and Anderson 1994).
62. CAPE SABLE SEASIDE SPARROW. The endangered Cape Sable seaside sparrow (Ammodramus maritimus mirabilis) breeds in the graminoids.
63. PASSERINES. The passerines that roost or breed in the graminoids include the red winged blackbirds (Agelaius phoeniceus), common yellowthroat (Geothlypis trichas), swamp sparrow (Melospiza georgiana), eastern meadowlark (Sturnella magna), boat-tailed grackle (Quiscalus major) and the common grackle (Quiscalus quiscula) (Stevenson and Anderson 1994).
    

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3.H Detritus Compartments

Detritus has been divided into three separate compartments:

64. SEDIMENT CARBON. Includes all the non-living organic carbon available in the first 10 centimeters of sediment.
65. LABILE DETRITUS. Liable detritus is organic matter in the water column that decomposes at a relatively fast rate. As with the cypress network, we use the information reported in Dierberg and Ewel (1986) for the decomposition rate of labile detritus (5.7/y.)
66. REFRACTORY DETRITUS. Refractory detritus represents organic matter that decomposes at a relatively slower rate than labile detritus (0.17.y^-1) (Dierberg and Ewel, 1986).

Seasonality at this latitude is marked more by variations in freshwater input than by changing temperature. Thus, two separate networks mimic seasonality: one for the wet season (from June to November) when freshwater inputs are high and another for the dry season (December to May), when inputs are relatively low.


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