John J. McDermott

THE WESTERN PACIFIC BRACHYURAN HEMIGRAPSUS SANGUINEUS (GRAPSIDAE) IN ITS NEW HABITAT ALONG THE ATLANTIC COAST OF THE UN11ED STATES: REPRODUCTION

The Asiatic crab Hemigrapsus sanguineus, originally found as a single specimen in a rocky intertidal location in New Jersey in 1988, now has a geographical range in the western Atlantic from Massachusetts to North Carolina. In New Jersey, the crab reproduces from late April through September, and laboratory observations revealed that some crabs produce at least 2 broods in a season. Ovigerous females ranged from 12.1-35.8 mm in carapace width (CW), but relatively few females were sufficiently developed to reproduce at the lower end of this range. The abdominal width/CW ratio must be >0.60 for female crabs to be considered mature. Analysis of 300 females >12.0 mm CW revealed that crabs >17.0 mm are likely to be mature. The mean time required for embryo development to hatching of zoeae in the laboratory at 19-20?C was 22.3 ? 1.8 days (range 20-25 days; N = 8). Viable second broods produced in the laboratory did not require a second copulation. The number of embryos in broods of H. sanguineus was positively correlated with CW (N = 50), with some crabs ovipositing >40,000 eggs.

The feeding biology of Nipponnemertes pulcher (Johnston) (hoplonemertea), with some ecological implications

Abstract Nipponnemertes pulcher, the dominant hoplonemertean of the Haploops community in the Danish Oresund (74/m2), fed in the laboratory on the amphipods Haploops tenuis, H. tubicola and Corophium volutator. The less frequent sympatric species Amphiporus bioculatus and A. dissimulans fed on H. tenuis. Haploops spp. are the dominant amphipods in the community and probably represent the major prey of these suctorial nemerteans. The feeding behavior of N. pulcher is similar to other amphipodophagous species except that the stout body is used to envelop the prey while feeding, and there is less pronounced peristaltic action of the body wall. The feeding rate, as determined in the laboratory, declines precipitously after the first 24 hr, assuming a rate that may be more in accord with natural circumstances. N. pulcher was unpalatable to the teleost Myxocephalus scorpius in laboratory tests.

Predation of the razor clamEnsis directus by the nemertean wormCerebratulus lacteus

The nemertean wormCerebratulus lacteus feeds on the razor clamEnsis directus by entering the burrow from below and engulfing its anterior end. The clam is forced to project much of its body above the surface (sometimes leaving the burrow), thus becoming subject to surface predators and desiccation. This predation was observed from New Jersey to North Carolina.

Incidence and host-parasite relationship of Leidya Bimini (Crustacea, Isopoda, Bopyridae) in the Brachyuran Crab Pachygrapsus transversus from Bermuda

Abstract Pachygrapsus transversus (N = 1814) from intertidal locations in eastern Bermuda were examined from 1973–78 for the branchially infesting bopyrid isopod Leidya bimini. In two main collecting areas, Whalebone Bay(N = 1280) and Ferry Reach (N = 489), the incidence of infestations with all life history stages was 9.0 and 29.5%, respectively. This difference is explained by the larger numbers of older crabs in the Ferry Reach samples. The mean width of crabs infested with mature female isopods was similar for both locations (14.4 versus 16.0 mm, respectively). Five-hundred and eleven isopods were recovered from 1814crabs: 106 (20.7 %) cryptoniscids, 45 (8.8 %) sexually undifferentiatedjuveniles, 152(29.7%) males, 112(21.9%) immature females, and 96 (18.8%) mature females. Limited data suggest that the main period for cryptoniscid invasion of crabs is from April through July. None of the 149 ovigerous crabs, among 857 females from the two main collecting areas, harbored mature isopods, indicating cast...

The role of hoplonemerteans in the ecology of seagrass communities

Seagrasses of the world harbor a rich and varied fauna, but a review of the literature revealed that little has been done to evaluate the ecological importance of nemerteans in such communities. Monostiliferous hoplonemerteans are common inhabitants of some seagrasses, e.g. eelgrass (Zostera), but generally they are seldom collected or identified or are apparently absent in other species such as schoalgrass (Halodule) or turtlegrass (Thalassia). Nineteen species of hoplonemerteans (four families) have been identified from eelgrass beds around the world; they exist mainly as epifauna, and all except two species are probably suctorial feeders. Some palaeonemerteans (2 species) and heteronemerteans (4 species) are also associated with eelgrass, but mainly as infauna. Suctorial nemerteans (4 species in 3 families) from eelgrass beds located along the mid-Atlantic coast of the United States feed in the laboratory on a variety of amphipod species that inhabit eelgrass. Tubicolous species (e.g. Corophium) seem to be preferred. Zygonemertes virescens feeds on nine species of amphipods belonging to six families, and is the only species to feed on isopods (3 species). Analyses of field studies on the occurrence of hoplonemerteans in eelgrass beds in Virginia and New Jersey, along with available information on the food habits of these worms, were used as a basis for demonstrating their potential importance as predators of peracarids in seagrass systems. More careful methods for collecting and identifying worms, continued studies on food preferences and rates of predation, and emphasis on the population dynamics of worms and prey, are recommended in order to evaluate the role of suctorial hoplonemerteans in the ecology of seagrasses.

Status of the Nemertea as prey in marine ecosystems

Nemerteans are predators of a wide variety of animals, but little is known of their role as prey for other animals. The presence of toxins in the tissues and secretions of these worms has led to the assumption usually suggested that they are ingested only rarely. However, analysis of a Food Habits Data Base from the United States National Marine Fisheries Service, compiled for fishes collected in the Atlantic Ocean from the Canadian border to Cape Hatteras, North Carolina (1973–1990), showed that nemerteans were recovered from the stomachs of 27 species of fishes in 14 families. They were found in 223 of 26 642 (0.84%) fish stomachs examined in the laboratory, but only in 0.09% of 58 812 fish examined in the field. Among species in the former category, for which ≥1000 were examined, the winter flounder, Pseudopleuronectes americanus(Walbaum), and the yellowtail flounder, Limanda ferruginea (Storer), had the greatest frequency of nemerteans, 71 of 1545 (4.6%) and 33 of 1045 (3.2%), respectively. These nemerteans were identified as Nemertea, Cerebratulus sp. or Micrura sp., but it is likely that they were all of a Cerebratulus-like type. Nemerteans have also been recorded from the guts of eight additional species (including four additional families) of fishes collected from the western Atlantic Ocean, Gulf of Mexico, eastern Pacific Ocean (Washington, Alaska), North Sea and Indian Ocean off South Africa. The black-bellied plover, Pluvialis squatarola(L.), semipalmated plover, Charadrius semipalmatus Bonapart and the herring gull, Larus argentatus Pontoppidan are the only three species known to feed on nemerteans (Cerebratulus lacteus (Leidy) and Paranemertes peregrina Coe by the black-bellied plover and C. lacteus by the other species). Several species of nemerteans are known to ingest other nemerteans, and several arthropods, a squid, and a few other invertebrates also feed on these worms. On the other hand, careful laboratory studies have shown that some members of the Palaeonemertea, Heteronemertea and Hoplonemertea, when fed to various species of fishes, crustaceans (Astacidea, Anomura, Brachyura and Amphipoda) and a polychaete, were rejected, usually violently. There is a history of using large nemerteans, e.g. Cerebratulus lacteus and Polybrachiorhynchus dayi, as bait by sport fishermen in the United States and South Africa. The incongruity of successfuly using these toxic animals to catch fish is discussed in relation to conclusions on the importance of nemerteans as prey in the marine environment.

Ectosymbionts of the non‐indigenous Asian shore crab, Hemigrapsus sanguineus (Decapoda: Varunidae), in the western north Atlantic, and a search for its parasites

Over 560 Asian shore crabs, Hemigrapsus sanguineus, collected mainly in the spring of 2005 and 2006 from rocky intertidal locations in southern New Jersey, were examined for epibionts. Small numbers of the sympatric green crab, Carcinus maenas, and the Atlantic mud crab, Panopeus herbstii, were examined for epifauna to compare with H. sanguineus. Blue mussel spat, Mytilus edulis, and the encrusting, cheilostome bryozoan, Conopeum tenuissimum, were the dominant ectosymbionts of the shore crab, with prevalences of 22.2 and 32.1%, respectively; ranges of intensity were 1–146 spat/crab and 1–31 colonies/crab. Both species are incidental symbionts. Larger crabs had higher prevalences and intensities of C. tenuissimum colonies, and these colonies displayed a distinct pattern of attachment to the carapace which seemed to be related to crab morphology and habitat. Much less common was the encrusting, ctenostome bryozoan Alcyonidium albescens, a facultative symbiont species with a prevalence of 3.4%. Other epibionts were the encrusting, cheilostome Membranipora tenuis, the tubicolous polychaetes Hydroides dianthus, Sabellaria vulgaris, and Spirorbis sp., the barnacles Balanus improvisus and Semibalanus balanoides, and unidentified thecate hydroids, all incidental symbionts with prevalences from 0.2 to 3.2%. The total number of known ectosymbionts of H. sanguineus, including additional species found previously in the USA and the western Pacific, is 13. Carcinus maenas and P. herbstii share some of the same symbionts. Rhizocephalan externae were not observed in any of the crab species used in this study, nor were gill parasites or internal parasites found among 248 specimens of H. sanguineus.

Feeding Behavior of Dipolydora commensalis (Polychaeta: Spionidae): Particle Capture, Transport, and Selection

Particle capture, transport, ingestion, and selection mechanisms used by Dipolydora commensalis, a symbiotic worm that inhabits burrows it produces in hermit crab shells, were studied in the laboratory. Worms removed from shells inhabited by Pagurus longicarpus were placed in capillary tubes for observation and video-microscopy of feeding. Particles were captured by the palps and transported to the mouth by ciliary and muscular action. Mean transport rates for cysts of Artemia from the distal ends of the palps to the mouth ranged from 0.7 to 1.3 mm/sec; those for glass beads, from 0.2 to 0.8 mm/sec. Upon reaching the mouth, particles were engulfed by the lateral lips and ingested. Worms feeding on large particles (>0.2 mm) repeatedly arched the anterior end of the body. Nauplii of Artemia were used to determine the ability of the worms to feed on small motile organisms over a 24-h period in the dark. In six trials the percentage of nauplii ingested ranged from 58% to 76%. In particle selection experiments, worms were offered uncoated glass beads and beads coated with fluid from the ribbed mussel, Geukensia demissa. In two experiments 91% and 89% of coated glass beads were ingested as compared to 15% and 4% of uncoated beads, respectively. Video-analyses of feeding sequences showed that cysts were often partially ingested and then ejected from the mouth. Uncoated beads transported along the palps often never reached the mouth. These results indicate that D. commensalis can actively select particles at the mouth and possibly during transport along the palps. Additional key words: suspension feeding, deposit feeding, feeding biodynamics, videoanalysis, Annelida Polychaetous annelids of the family Spionidae occupy a variety of marine and estuarine habitats, ranging from soft-bottom sediments to hard calcareous substrates (Fauchald & Jumars 1979). The biology of shell-boring spionids has been studied in considerable detail, in part due to their effects on commercially important species of bivalves (e.g., Haigler 1969; Blake & Evans 1973; Zottoli & Carriker 1974; Sato-Okoshi & Okoshi 1993). Blake (1996) referred those species in the genus Polydora bearing notosetae on setiger 1 to the genus Dipolydora VERRILL 1879, making the current combination for the species under study Dipolydora commensalis (ANDREWS 1891). Although many spionids are non-specific borers, D. commensalis burrows exclusively into gastropod shells inhabited by hermit crabs. The burrows of the worm often begin on the columellar side of the shell aperture and extend to a Author for correspondence. E-mail: jwil4024@uriacc.uri.edu the internal apex of the shell via a thin secreted calcareous tube (Andrews 1891; Hatfield 1965; Radashevsky 1989). D. commensalis is usually classified as a commensal, but recent research suggests that the nature of this association with hermit crabs may require some re-evaluation. Buckley & Ebersole (1994) showed that the strength of shells inhabited by spionids is reduced, decreasing the resistance of shells to crushing forces applied by predators. The feeding biology of polychaetes has been summarized by Fauchald & Jumars (1979) and several spionids have been investigated in detail (Dorsett 1961; Dauer et al. 1981; Levin 1981; Jumars et al. 1982; Dauer 1983, 1984, 1985; Yokoyama 1988; Miller et al. 1992; Bock & Miller 1996; Shimeta & Koehl 1997). In most spionids, a pair of peristomial palps are used to capture and transport food particles for ingestion. Particles are usually transported, by a combination of muscular movement and ciliary action, in a median ciliated groove (Dorsett 1961), although in at This content downloaded from 157.55.39.186 on Sun, 09 Oct 2016 06:17:45 UTC All use subject to http://about.jstor.org/terms Williams & McDermott least two species the palps lack a ciliated groove (Dauer & Ewing 1991). Spionid polychaetes have been classified as either suspension-feeders or deposit-feeders, or as suspension-deposit feeders (Dauer et al. 1981). Suspensiondeposit feeding spionids have a mixed mode of feeding, depending on environmental conditions, and change their feeding behavior in the presence of particle fluxes or deposited material (Taghon et al. 1980; Miller et al. 1992; Bock & Miller 1996). Particle capture in spionids occurs primarily through direct interception of food by the palps, although inertial impaction and gravitational deposition may have slight effects (Taghon et al. 1980; Shimeta & Koehl 1997). Several physical limits may affect the ability of a worm to feed on particles. Mucus secreted at the distal end of the palps and along the ciliary oral groove has a limited strength of adhesion to intercepted particles (Jumars et al. 1982). There are also limits to the size of particles that can be transported along the palps, via ciliary and/or muscular action. The size of the mouth and/or pharynx acts as the final determinant of the size of particles that can be ingested. Most studies on the feeding biology of spionids have involved species inhabiting soft-bottom substrates. The use of soft-bottom spionids has allowed investigators to study the feeding biology in a variety of contexts (e.g., Dauer et al. 1981; Jumars et al. 1982; Taghon 1982; Taghon & Jumars 1984; Shimeta 1996), in particular, active and passive particle selection. Active particle selection in spionids occurs at the mouth, pharynx, or along the ciliated oral groove of the palps (Dauer et al. 1981; Levin 1981; Shimeta & Koehl 1997). Passive selection results from particle loss due to limited adhesive strength of mucus on the palps (Self & Jumars 1978; Taghon 1982; Shimeta & Koehl 1997). Such particle loss can occur at the point of initial contact between palp and particle or during particle transport along the palp (Taghon 1982). Size, specific gravity, and texture of food particles can affect the passive selection mechanisms in spionids (Self & Jumars 1978; Jumars et al. 1982; Taghon 1982; Shimeta & Koehl 1997). Passive selection mechanisms, therefore, can cause preferential ingestion of particles that are smaller, rougher, and have lower specific gravities. Passive loss could also determine the ability of a polychaete to engage in a macrophagous, predatory mode of feeding documented in certain spionids (Dorsett 1961; Jumars et al. 1982). One might expect differences between the feeding behavior of soft-bottom species and D. commensalis due to the distinct habitat of this species. The burrow in which D. commensalis lives may prevent it from feeding at the sediment-water interface. Additionally, interactions with the hermit crab host may influence the feeding behavior of the worm, which has been reported to feed on fine particles suspended in the branchial currents of the crab (Dauer 1991; Radashevsky 1993), on particles attached to the legs of the crab (Dauer 1991), and on nauplii of Artemia being fed to the longwrist hermit crab Pagurus longicarpus SAY 1817 (J.J. McDermott, unpubl.). Since the original description of D. commensalis, only nonquantitative obs vations on the feeding behavior of this polychaete have been reported (Radashevsky 1993); however, palp morphology and its relation to feeding mechanisms on small particles was studied by Dauer (1991). The objective of our study was to investigate the feeding biology of D. commensalis, focusing on mechanisms of particle capture, transport, ingestion, and selection, by combining observations of behavior with quantitative measurements of deposit and suspension feeding. The observation of feeding behavior and measurements of feeding rates were made possible by removing the worms from the shells. Worms placed in glass tubes were compared with those in shells inhabited by P. longicarpus, as they manipulated cysts and swimming nauplii of Artemia and glass beads. Videomicroscopy, a valuable aid in studying the feeding behavior of small invertebrates and their larvae (e.g., Strathmann 1982; Gilmour 1985; Holland et al. 1986; Gallager 1988; Emlet 1990; Hansen & Ockelmann 1991; Nielsen et al. 1993; Mayer 1994; Chen et al. 1996; Hart 1996; Shimeta & Koehl 1997), was used to record the feeding rates of the worms and mechanisms involved in feeding.

Carcinonemertes pinnotheridophila sp. nov. (Nemertea, Enopla, Carcinonemertidae) from the branchial chambers of Pinnixa chaetopterana (Crustacea, Decapoda, Pinnotheridae): description, incidence and biological relationships with the host

A new species of Carcinonemertes, C. pinnotheridophila, is described and illustrated. The worms were found in the pinnotherid crab Pinnixa chaetopterana collected from the coasts of New Jersey, North Carolina and Florida. The anatomy of the new species is compared and contrasted with that of other members of the genus Carcinonemertes and an emended generic diagnosis is provided. The nemerteans only inhabit female hosts, crabs being infested with one or two mature female worms but with no more than one ensheathed in each branchial chamber; one or more smaller male nemerteans may be associated with each female. Sheaths are attached to the medial portion of the host branchial exoskeleton, and project through an opening in the floor of the chamber to exit via another aperture in the sternum; the anterior part of the sheath opens in the excurrent canal of the branchial chamber. Female worms cement their oval egg sacs on the pleopods to which the crabs eggs are also attached. Attachment, development and hatching of both host and symbiont eggs are synchronous. The incidence of infestation, reproductive potential of the nemertean, damage to its host and tolerance of the crabs growth cycles are described.

REPRODUCTION IN THE HERMIT CRAB PAGURUS LONGICARPUS (DECAPODA: ANOMURA) FROM THE COAST OF NEW JERSEY

Trends in reproductive activity of an intertidal population of Pagurus longicarpus from coastal New Jersey were studied from 1985-1990. Brooding occurred from late March-October, with a sharp peak in ovigerous crabs in April (70.6-96.4% of yearly total). Mean water temperatures at the commencement of breeding in March and April were <10?C. A rapid decline in ovigerous crabs occurred in May and June and throughout the summer; ovigers were rare in September and October (4 among 849 crabs). The smallest oviger was 1.85 mm in carapace shield length (SL), although minimum length was generally 2.2-2.3 mm. The number of embryos in a brood was positively correlated with SL, but there was considerable variability in this relationship. The maximum number of embryos in a brood among 474 counted, was 1,426 (from a 3.70-mm crab). Embryos were attached to pleopods 2, 3, and 4, with most attaching to the third. Mature oocytes observed and counted in nonovigerous and postovigerous crabs suggest that some crabs may produce more than 1 brood in a season. Recruitment of benthic juveniles to the population began in May and continued throughout the summer and fall.