Connecticut College Digital Commons @ Connecticut College Bulletins Connecticut College Arboretum 10-1974 Bulletin No. 20: Tidal Marsh Invertebrates of Connecticut Nancy C. Olmstead Connecticut College Paul E. Fell Connecticut College Follow this and additional works at:http://digitalcommons.conncoll.edu/arbbulletins Part of theAquaculture and Fisheries Commons,Biology Commons,Marine Biology Commons, Plant Sciences Commons, and theTerrestrial and Aquatic Ecology Commons Recommended Citation Olmstead, Nancy C. and Fell, Paul E., "Bulletin No. 20: Tidal Marsh Invertebrates of Connecticut" (1974).Bulletins.Paper 19. http://digitalcommons.conncoll.edu/arbbulletins/19 This Article is brought to you for free and open access by the Connecticut College Arboretum at Digital Commons @ Connecticut College. It has been accepted for inclusion in Bulletins by an authorized administrator of Digital Commons @ Connecticut College. For more information, please contact [email protected]. The views expressed in this paper are solely those of the author. fIDAL MARSH INVERTEBRATES OF CONNECTICUT THE CONNECTICUT ARBORETUM BULLETIN NO.20 CONNECTICUT COLLEGE NEW LONDON, CONNECTICUT TIDAL MARSH INVERTEBRATES OF CONNECTICUT Nancy C. Olmstead Connecticut Arboretum and PaulE. Fell Connecticut College Drawings by Sibyl A. Hausman Contents Foreword-William A. Niering 2 Tidal Marsh Invertebrates. ..........•................. ............ 3 Identification of the Invertebrates. ........... ....... ........... .. ... 6 Cnidarians 8 Molluscs 8 Snails 8 Bivalves ...........•................•.•..........•.......... 12 Arthropods 13 Crustaceans 13 Arachnids ........ ........................................... 20 Insects .......................................•............. 22 Vertebrates 33 Suggested Reading 35 CONNECTICUT ARBORETUM BULLETIN NO. 20 OCTOBER 1974 FOREWORD In our efforts to preservethe tidal marshes ofConnecticut the Arbore- tum has spearheaded the movement to highlight the roles of tidal marshes in marine productivity through a seriesof Bulletinsoriginating as early as 1961.Although protective tidal marsh legislation has been enacted, there is still a great need to create a further awareness of the ecologicalvalueofthetidal marsh-estuarine ecosystem. Many organisms at this land-water interface playa role inthisproductivity. Among them are the invertebrates, including the insects, arachnids, crustaceans, and molluscs, about which this Bulletin is concerned. Although lacking backbones common to higher animals, they are of great importance as intermediate transformers of much of the energy tied up in the tidal marsh plants. They are also important in the recycling of mineral nutrients which in turn stimulate the phytoplankton, the base of the marine foodchain. Thus these organisms are a vital part ofthe complex self-perpetuating system that supports the great productivity of the estuary. No nutrients in the form of commercial fertilizers are needed to produce the shellfish and finfish so prized and taken in such great quantities byman fromthe mud flats and offshore waters. In the preparation of this publication, we are most grateful to Mrs. Nancy C. Olmstead, Dr. Paul E. Fell, and Miss Sibyl A. Hausman for their professional talents and dedicated efforts. Their first-hand field observations and insightslend a unique qualitytothis volume. It is hoped that this publication will be useful to laymen, teachers andstudents who areinterested inlearning the diversityoflifeforms and inunderstanding the rolethese organisms playinthe tidal wetlands. Vdt~(j~ Director 2 TIDAL MARSH INVERTEBRATES THE TIDAL MARSHES which fringe the coastline are recognized as being among the most hiologically productive areas in the world. Not onlydo they provide food, shelter, and nesting sites for many bird species,but the baysand tidal creeks which border them serve as nurseries and spawning grounds for manyvarieties offishandshellfish. Inaddition,deadanddecayingmarshgrasses are exported to the estuaries as detritus (all the particulate organic matter in- volvedin the decomposition ofdead organisms). This detritus, along withalgae and phytoplankton, becomes food, either directly or indirectly,for thefishand shellfish of the shallow coastal waters. Since the great majority of the fish caught for market throughout the world come from these coastal waters (I), tbe importance of this nutrient input can be appreciated. Itis estimated that Connecticut's 15,500acresoftidal marsh produce42,000 tons of plant material yearly (2), much of whichiseventuallycarried away by tbe tides to the offshore waters. Tall saltwater cordgrass iSpanina oltemifloray forms a belt along tbe seaward edges of tbe marsb and along tbe banks ofthe tidal creeks and mosquito ditches, and covers between ten and twenty percent of tbe surface of the tidal marsbes in Connecticut (2).This area, wbichisinun- dated by every tidal cycle, is defined as low marsh. In tbe high marsh meadows, which are not submerged by all high tides, tbe principal vegetation consists of saltmeadow grass iSpartina patens), spikegrass [Distichlisspicata], and blackgrass (Juncus gerardi], a rush. A stunted form ofsaltwater cordgrass appears in high marsb areas in depressions known as pannes. Other areas (forb pannes) are covered with colorful flowering herbs such as sea lavender (Limonium caro/inianum), gerardia [Gerardia maritima), and aster (Aster tenuifolius]. Along the upland border of the marsh, in areas which are sub- merged by only the highest spring or storm tides, the marsh elder shrub (Iva frutescens} is common. All of these plants are described in Tidal Marshes of Connecticut (3). The EcologicalRoleofInvertebrates The invertebrate animals (such ascrabs, snails, mussels,spiders, andinsects) whichare found among the grasses and inthe tidal creeksandmosquito ditches of the marsh play many important roles in thishighly productivesystem.They are amajor part of both the marine and terrestrial foodchains.Whenthemarsh is covered by high tides, the blue crabs, eels, and minnows of the creeks and ditches are able to invade the marsh and feeduponthe smallinvertebrates found there, In turn, these animals are fed upon by the larger fish of the offshore waters. The invertebrates also make up the largest percentage of the diet of many species of birds found on the marshes (4). A simplified food chain in- cluding tidal marsh invertebrates isshown onpage 5. Lessobvious but equally important is the rolewhichthe marsh invertebrates play in raising t1henutritional value of the detritus wbichis exported to the estuaries. Dead marsh grasses are broken into progressivelysmaller pieces by tbe feeding activities of these animals, first bythe animals whichfeeddirectly upon the grasses, and then bythose which feedupon thepartially decomposed grasses in the mud and peat. This progressive fragmentation of the grasses makes them more accessible to the bacteria whichareessentialfortheir ultimate breakdown. Grass which has been broken down into detritus contains more protein than either living or dead grass (5), and it is therefore of greater 3 biological value for fish and shellfish. The invertebrates also enrich the mud withtheir fecesanddeadbodies. The invertebrates whichinhabit the tidal marshes encounter many stresses. They must be able to tolerate alternating periods of submergence and ex- posure and with them considerable changes intemperature. In addition, there may be variation in the salinity of their surroundings, depending upon the amount ofrainfall andthedegree ofevaporation. Becauseofthesestresses there is not a great diversity of animal species, but those species which have been ableto adapt to marsh lifeare often present inverylarge numbers. Few ofthese specieseat thegrassesdirectly. Most feedonmudalgae, bacteria, and decaying vegetable and animal material. It is the availability of an abundant supply of detritus andthe lack ofinterspecific competition whichpermits the presence of such large populations. In spite of their numbers, most of the animals which inhabit the marsh are inconspicuous. Few of the invertebrates are large or highlycolored, and themarsh plants usually provideadense coverfOTtbem. In order to studythese animals,one mustlook carefullyfor them. Some oftheinvertebrates inhabit onlythelowmarsh, whileothers inhabit the high marsh. Their distribution is related mainlyto the frequency of tidal inun- dation (hydroperiod), which is also an important factor in the distribution of the marsh grasses. Someinvertebrates are foundinboth thelowand high marsh areas. Ingeneral, thesearethe insects,whichareabletoescape submergence by flying or crawling away. and whose distribution is determined more by their food preferences than byhydroperiod. Specific quantative data presented here were obtained from studies of the invertebrate populations of the Cottrell Marsh, Stonington, Conn., an area owned by the Nature Conservancy (6). Other distributional data utilized were obtained from studies of the inverte- brates foundonten saltmarshes ineastern, central,and westernConnecticut (7). Literature Cited (I) Teal,J.andM.Teal.1969.LifeandDeathoftheSaltMarsh.Lillie,BrownandCo., Boston, Toronto. (2) Niering, W.A. and R.S. Warren. 1974. Tidal Marshes of Connecticut: Vegetation, Micro-Relief and Environmental Impacts. In Tidal Wetlands of Connecticut: Vegetation and Associated Animal Populations. Vol. 1. (W.A. Niering and R.S. Warren, eds.) Dept. of Environmental Protection, State of Connecticut, in coop- eration with the Bureauof Sports Fisheries andWildlife, U.S. Dept. Int. (3) Roberts, M.F. 1971. Tidal Marshes of Connecticut: A Primer of Wetland PLants. Conn. Arboretum Reprint Ser. No. 1. (4) Bourn. W.S. and C. Cottam. 1950. Some Biological Effects of Ditching Tidewater Marshes. U.S. Dept. tnt.. Fish and WildLifeServ..Res. Rep. 19. (5) Odurn, E.P. and A.A. De13Cruz. 1967. Particulate Organic Detritus in a Georgia Sail Marsh-Estuarine Ecosystem. In Estuaries. {G.H. Lauff, ed.) American Association for theAdvancement of Science. Pub!.No. 83. Washington, D.C. (6) Olmstead.N.C. andP.E. Fell. 1974.TheInvertebratesoftheCottrellSalt Marsh in Eastern Connecticut, with an Emphasis on the Salt Marsh Snail, Melampus bidentatus. In Tidal Wetlands of Connecticut: Vegetation and Associated Animal Populations, VoL I.(W.A. Niering andR.S. Warren,eds.] Dept. of Environmental Protection, State of Connecticut, in cooperation with the Bureau of Sports FisheriesandWildlife,U.S.Dept.Int. 0) Pellegrino. P.E. and A.T. Carroll. 1974. The Distribution of invertebrates in Connecticut Salt Marshes. In Tidal Wetlands of Connecticut: Vegetation and Associated Animal Populations. Vol. I. {W.A. Niering and R.S. Warren, eds.) Dept. of Environmental Protection, State of Connecticut. incooperation with the BureauofSportsFisheriesandWildlife,U.S.Dept.lnt. 4 • FOOD CHAIN IV III Mammals DECOMPOSERS Simplified food chain of tidal marsh animals. The different trophic (feeding) levelsare represented by Roman numerals. Level I,the baseofthe foodchain, is made up of the detritus which results from the breakdown of dead animal and vegetable material, and of the living green plants and algae (the primary producers) which trap energy from the sun. Subsequent trophic levels are increasingly removed from the primary source ofenergy. LevelII consistsofthe herbivores, which feeddirectly onthe plants and algae,and thedetritus-feeders. The small predators, or carnivores, whichpreyupon theherbivores anddetritus- feeders make up Level III. The marsh food chain culminates with Level IV, thelarger predators, which feedupon the animals in LevelIII. The names of those animals which are both herbivorous and carnivorous straddle the line between Level Il and Level III. Within a few of the groups some species are predators (P), whileothers are detritus-feeders (D).(Drawing byAllen T. Carroll) 5 IDENTIFICATION OF THE INVERTEBRATES THE MARSH INVERTEBRATES discussed here are grouped according to phyla, classes, orders, and species. Species within a given class are arranged according to their distribution in the marsh, starting with those animals found inthe tidal creeks and mosquito ditches (and includingsome vertebrates), and progressingthrough thelowmarsh animals to thoseofthe high marsh meadows, andfinally,tothose invertebrates characteristic ofthe upland borders. D1ustrations.Illustrations accompany the description of most of the animals discussed. Lines point to important distinguishing characteristics. Drawings are includedof isolated body parts, wherethese are important in identification. A bar near the drawing indicates the actual size of the animal. For a fewof the larger animals the bar is in two sections. Only the common names of animals are given with the illustrations except where common names refer to entire families (as, for instance, with ladybug beetles). In these instances both the common name and the generic name of the particular animal are given, if the latter isusedinthe text. Key, To aid the reader in identifying specimens, a simple key is presented below. The paired numbers on the left present alternative characteristics. Choose the one which describes the specimen and follow the numbers at the right whichlead either to the next choice or to the name of the phylum, class, or order to whichthe animal belongs and to the page number on which discus- sion of the animal begins. Larval forms of some beetles, flies, and butterflies are not described in the key but are illustrated on page 32. Three vertebrate speciesnot included in the key (the common mummichog, the American eel, andthediamond-back terrapin) arediscussed onpages 33and 34. Key to Common Invertebrates I. Animals non-motile, no jointed appendages, body not enclosed in a shell-e-Cnidaria(seaanemones), p.8. 1. Animals not asabove, generally motile " 2 2. Animals wit~ut jointed appendages; body enclosed in a hard, cal- careous shellconsisting ofoneortwovalves-Mollusca. . ..... 3 2. Animals with jointed appendages, body not enclosed in a one- or two-valvedshell-Arthropoda '.,......... .. ..... 4 3. Shellconsistingofonevalve-Snails, p.8. 3. Shellconsistingoftwovalves-Bivalves, p. 12. 4. Bodytypically with a horny shell, appendages often with pincer-like terminal segments-Crustacea " 5 4. Body without a shell, appendages generally without pincer-like ter- minal segments ............... ....... .. ..... 10 5. Animals with 2 pairs of appendages for grasping, 5 pairs of walking legs, 6 pairs of legs for swimming or leaping; body laterally compressed-Amphipoda (sand fleas, beach hoppers), p. 16. 5. Legsfewerinnumber " 6 6 6. Animals with 7pairs ofwalking legs, body dorsoventrally flattened- Isopoda (sow bugs, wood lice), p. 18. 6. Legs fewer in number. ................................ ...... 7 7. Animal with 6 pairs of legs, used only in feeding; non-motile; body enclosed in6 calcareous plates-Cirripedia (barnacles), p. 20. 7. Legs fewer in number, body not enclosed incalcareous plates.. . .... .. 8 8. Animals with 5pairs of legs for walking orswimming-Decapoda .. 9 8. Legs fewer in number , 10 9. Body dorsoventrally flattened, abdomen much reduced, body length generally over 20 mm-Crabs, p. 13. 9. Body laterally compressed, abdomen long, body length generally under 20 mm-Shrimp, p. 16. 10. Animals with 4 pairs oflegs-Arachnida ...................... II 10. Animals with 3pairs of legs-Insecta, p.22 12 II. Body divided into cephalothorax and abdomen-Spiders, p. 21. II. Body oval, not divided into cephalothorax and abdomen-Mites, p. 22. 12. Minute wingless insects-Collembola (springtails), p. 27. 12. Insects generally with wings ······ 13 13. Insects with one pair of wings, second pair represented only by a pair of knob-like structures-Diptera (flies and mosquitoes), p. 27. 13. Insects with two pairs of wings. ..... ............................ 14 14. Hind legs enlarged for jumping-Orthoptera (grasshoppers and crickets), p. 30. 14. Hind legs otherwise 15 15. Forewings leathery throughout, hindwings membranous-Coleoptera (beetles), p. 24. .' 15. Forewings otherwise 16 16. Forewings leathery at base, membranous at tip. beak arising from front of ventral surface ofhead-Hemiptera (true bugs), p. 28. 16. Forewings membranous throughout or wings lacking , 17 17. Wings present, beak arising from back of ventral surface of head- Homoptera (aphids, planthoppers, leafhoppers), p. 30. 17. Wings present, covered with overlapping scales-Lepidoptera (butter- flies and moths), p. 32. 17. Wings present or absent, ovipositor present and often modified as a sting-Hymenoptera (ants), p. 30. 7