Changes in the abundance and distribution of sav along Florida’s springs coast: a comparison based on aerial photography acquired in 1992 and 1999

Indiscriminate fusion of swimming sponge larvae

Katie E. McGhee.* Department of Biological Science, Florida State University, Tallahassee, Florida 32306-1100; e-mail [e-mail].

For sedentary marine invertebrates, allorecognition systems allow individuals to distinguish between genetically similar and distinct tissue they may encounter and are thought to reduce tissue fusion with individuals other than self or kin. However, the costs and benefits associated with fusion at a sessile adult stage may be drastically different than those associated with fusion at a mobile larval stage where size may be critical and encounters can be avoided or pursued. The purple sponge, Haliclona sp., releases free swimming larvae that fuse and produce swimming chimeric larvae without loss of metamorphic ability. Using these larvae, I investigated the effect of relatedness on larval fusion frequencies and whether larvae can distinguish between siblings, larvae from sponges at the same site, and larvae from sponges on islands separated by over a kilometer. Fusion frequencies averaged 13.4% and did not differ significantly between larval treatments indicating that larvae are unable to distinguish between individuals of varying relatedness. In addition, adult sponges differed significantly in the propensity of their larvae to fuse, suggesting the presence of individual strategies influencing the behavior of their larvae. These results indicate that contrary to the predictions of self- or kin-recognition theory, factors other than relatedness may be involved in determining the likelihood of larval fusion.

Responses of juvenile and adult Streblospio benedicti (Spionidae) to chemical cues bound to glass microbeads

H. K. Mahon* and D. M. Dauer. Department of Biological Sciences, Old Dominion University, Norfolk, VA, USA; e-mail [e-mail]; [e-mail].

Spionid polychaetes feed at the sediment-water interface using a pair of ciliated palps. Spionids select food particles based upon characteristics including size, texture and specific gravity. In addition, chemical cues also play an important role in selectivity. Juvenile and adult spionids may have different stable isotopic carbon signals, indicating the potential to differentiate chemical cues ontogenetically. In the present study, we tested the responses of juvenile and adult Streblospio benedicti to seven chemical cues bound to glass microbeads (five amino acids and two carbohydrates). All chemicals used were previously shown to increase feeding rates of spionids. For all seven chemical cues, juveniles and adults were highly selective of organically coated beads over uncoated beads (greater than 70%). Two of the cues showed significant differences between juveniles and adults. Juveniles were highly selective for threonine while adults were highly selective for proline.


Functional morphology of the setae of the slipper lobsters Scyllarides latus, S. aequinoctialis and S. nodifer's pereiopods

Cassandra Malcom* and Kari Lavalli. Southwest Texas State University, San Marcos, TX, USA

Setae of the pereiopods of three species of slipper lobsters, Scyllarides latus, S. aequinoctialis and S. nodifer (family Scyllaridea), were examined with a scanning electron microscope (SEM) and environmental electron microscope (EEM). The position, distribution, and structure of the setae was compared to the setae of members of two more commonly studied families of lobster: nephropids (American clawed lobster, Homarus americanus) and palinurids (Caribbean spiny lobster, Panulirus argus). These two families have been found to have very setose pereiopods with different setal types that function as both contact chemoreceptors (taste) and distance chemoreceptors (smell); some, such as hedgehog hairs and serrate setae, can function as both chemo- and mechanoreceptors. However, rather than having many types of setae like the nephropids or palinurids, we have only found simple and cuspidate setae on S. latus, S. aequinoctialis and S. nodifer. Slipper lobsters have hairs only at the proximal end of the dactyl and spread throughout the remaining segments (propus, carpus, merus, ischium, basis) of each non-chelate pereiopod. Tufts of these setae are found on the dactyl, while the remaining segments have setae spread randomly on their surface. Videotapes of feeding by these lobsters on bivalves indicates that they use the hard, nail-like dactyls to pry open the bivalves, whereupon they use their larger first pereiopods to hold the bivalve shell open and their second pereiopods to cut the bivalve's adductor muscles. Because of this feeding mode, hairs on the tips of the dactyl would be broken and damaged, presumably affecting their function. Thus, the location of hairs at only the proximal ends of the dactyl allows the lobster to use the dactyl tips as cutting appendages. We expect that neurological examination of the hairs at the proximal end of the dactyl will show those hairs to be chemosensory in function.

Interannual growth rate variation in the soft-shelled clam, Mya arenaria, and its relation to interannual temperature differences and habitat at Maquoit Bay, Maine

Kate R. Meltzer* and William G. Ambrose, Jr. Biology Department, Bates College, Lewiston, ME 04240, USA.

Internal annual growth bands in the soft-shelled clam, Mya arenaria, were used to determine age and growth rates of individuals collected different areas of Maquoit Bay, Maine. An annual index of growth was developed for years 1991 to 2001, accounting for age differences in growth rates using the von Bertalanffy equation. Interannual variations in growth were then related to interannual differences in temperature (air and water) and habitat (seagrass versus mudflat). Average lengths of two- and three-year old clams from Maquoit Bay were 38%-60% greater than two-and three-year old clams from six sites in a 1980 Maine study. Mya typically exhibits slow growth during winter, however the large size of young clams in recent years may be the result of milder winters that permitted faster growth. Therefore, we expect to find a strong positive correlation between warmer winter temperatures and faster clam growth. Seagrass in Maquoit Bay (45%, SD = 8% cover, shoot biomass = 7.8g, 2.9g; root biomass = 3.8g, 2.3g; and canopy heigh t= 31.4cm, 4.9cm) decreases water flow by 50% which may reduce food delivery. Nevertheless, preliminary results indicate that there is no difference in growth rate inside and outside the grassbed.


The variable effects of suspension feeders and nutrient enrichment on phytoplankton biomass in intertidal pools on Swan’s Island, Maine

Elizabeth T. Methratta.* University of Pennsylvania, Department of Biology, Philadelphia, PA 19104-6018, USA.

Questions of top-down/bottom-up regulation have been difficult to test experimentally in marine settings because nutrient manipulations are impractical in open systems. With few experimental studies addressing the roles of nutrients in marine systems, our understanding of how nutrients influence marine communities remains limited. Nutrient enrichment is suspected to play a prominent role in structuring intertidal pool communities. Tidepools on Swan’s Island, Maine that receive natural nutrient enrichment contain more phytoplankton biomass and fewer benthic organisms compared to those tidepools that are not nutrient enriched. The role of suspension feeders is unclear, because they may either reduce phytoplankton biomass by consumption, or increase phytoplankton biomass by enhancing the cycling of limited nutrients. Moreover, some suspension feeders are inefficient at retaining particles smaller than 2 to 5 micrometers in diameter, and so they may also cause shifts in the size distribution in the phytoplankton assemblage. Here I present the results of a 2-by-2 factorially designed experiment in which the factors of nutrients (ambient versus enriched) and planktivory by the blue mussel, Mytilus edulis, (mussels present versus mussels absent) were manipulated, and the response of phytoplankton biomass was measured over the course of several weeks. Initially, tidepools that received both nutrients and mussels showed greater phytoplankton biomass compared to others, although this effect was reversed on subsequent sampling dates, with these nutrient+mussel tidepools showing lower phytoplankton biomass compared to other treatments. Nutrients added alone had little positive effect on phytoplankton biomass. These results indicate that in intertidal pool communities, benthic suspension feeders are linked tightly to phytoplankton production by consumption and by nutrient cycling, and that these effects vary over time.


Patterns of herbivory and seaweed abundance in Florida Keys no-take reserves

Margaret W. Miller.* NOAA-Fisheries, Southeast Science Center, 75 Virginia Beach Dr., Miami FL 33149, USA.

Assessment of total seaweed biomass and herbivory pressure (using rope assays) has been undertaken at least semiannually in three no-take reserves and three adjacent reference sites in the Florida Keys National Marine Sanctuary (FKNMS) since reserve inception in 1997. The study was designed to test the hypothesis that top predator replenishment in FKNMS reserves would depress herbivore populations and, hence, herbivory, yielding higher seaweed abundance in no-take reserves. Seaweed abundance was highly variable and no treatment (Reserve vs. Reference) patterns are evident. Seaweed community analysis (using PRIMER v5 software) suggests deep (~18m) and shallow (~9m) communities are distinct so they were subsequently analyzed separately. Initially, shallow sites were quite homogenous and hence represent good “replicates” while the deep sites showed more differentiation at the initial (Oct.97) sampling. Slight differentiation of shallow Reserve vs. Reference seaweed assemblages was evident in recent samples while no such differentiation was indicated in recent deep samples.Relative herbivory between some reserve/reference site pairs appears to have shifted over the course of the project, but this is due most clearly to increase in herbivory at a single reference site and, perhaps, smaller decrease its reserve site pair.

Reef discovery, utilization and conservation in Antongil Bay, Republic of Madagascar

Kenyon Mobley,¹* Phaedra Doukakis,^2,3 and Mananjo Jonahson.^{3 1}Georgia Institute of Technology, School of Biology, 310 Ferst Dr. Atlanta, GA 30332-0230; e-mail [e-mail]; ²Wildlife Conservation Society, 2300 Southern Boulevard, Bronx, New York, 10460, USA; e-mail [e-mail]; ³Wildlife Conservation Society, Villa Ifanomezantsoa, Face II A 78 D, Soavimbahoaka; e-mail [e-mail].

Antongil Bay is a large estuary situated on the northeastern coast of Madagascar that supports a diversity of marine life including mangrove, seagrass, and coral reef communities. Despite the recent designation of two marine protected areas within the Bay as part of the Masoala National Park, the Bay remains relatively unexplored. During a recent field expedition, previously unknown reefs within the Bay (five eastern and one western) were surveyed for invertebrate taxa and relative coral cover. Eastern portions of the Bay support mixed coral/algal communities with comparatively higher species diversity than the western reef and are influenced by high turbidity and freshwater influx. The western reef, on the other hand, has a higher relative coral cover, lower invertebrate species diversity and is dominated by branching corals, principally Acropora spp. Future expeditions in the Bay are likely to reveal previously undocumented reef locations.

Interviews with local fishermen were conducted to identify target species, historical fishing grounds and the extent to which the reefs are presently exploited. Spearfishing, gill netting, and traditional hook and line methods are typically employed to catch reef fishes. We found reef fishing practices to be largely nondiscriminatory, and most all species of fishes are harvested and consumed. Reef invertebrates including sea cucumbers, tradacnid clams, and anemones are also harvested for subsistence-level consumption. As terrestrial resources throughout Madagascar disappear at an unprecedented rate, we predict marine resources may suffer from increased utilization and habitat degradation. Therefore continued research would benefit the development of appropriate management programs for reefs within Antongil Bay.

How does wave action stimulate thread production in Mytilus edulis?

G. M. Moeser* and E. Carrington. Department of Biological Sciences, University of Rhode Island, 100 Flagg Rd., Kingston, RI 02881, USA.

Sessile organisms on wave-swept shores must develop a means to remain attached to the substrate under a variety of conditions in order to survive. The mussel, Mytilus edulis, is a competitively dominant organism in this dynamic environment in part due to its ability to maintain a strong byssal attachment. Previous studies have suggested that M. edulis responds to increased wave action by increasing attachment strength through the production of more byssal threads, and it has often been assumed that flow is the main stimulus for this response. However, it remains unclear what specific aspects of wave action cue increased thread production. Mussels may potentially respond not only to unidirectional flow, but also to acceleration (flow-induced vibrations of the shell) or byssal loading (tension transferred from the threads to the byssal retractor muscles). This study focuses on the influence of acceleration and loading on the dynamics of M. edulis attachment strength. Field collected mussels were exposed to one of four two-factor treatments, consisting of (1) the presence or absence of mussel acceleration and (2) the presence or absence of fluctuating load on the mussel byssus, and the subsequent number of byssal threads produced was monitored. The relative importance of acceleration and loading in stimulating thread production will be discussed.


Biodiversity of Bear Seamount, New England seamount chain: results of exploratory trawling

J. A. Moore,¹* M. Vecchione,² K. E. Hartel,³ B. B. Collette,² J. K. Galbraith,⁴ R. Gibbons,² M. Turnipseed,⁵ M. Southworth,⁵ and E. Watkins.^{5 1}Florida Atlantic University, Honors College, Jupiter, FL 33458, USA; e-mail [e-mail]; ²National Marine Fisheries Service, National Systematics Laboratory, National Museum of Natural History, Smithsonian Institution, Washington, DC 20560, USA; ³Museum of Comparative Zoology, Harvard University, Cambridge, MA 02138, USA; ⁴National Marine Fisheries Service, Northeast Fisheries Science Center, Woods Hole, MA 02453, USA; ⁵Virginia Institute of Marine Sciences, Gloucester Point, VA 23062, USA.

Bear Seamount (39°55’N 67°30’W) is an extinct undersea volcano located inside the U.S. Exclusive Economic Zone south of Georges Bank. The fauna associated with the seamount was little known until twenty trawl stations were made December 2-7, 2000, by the NOAA research vessel Delaware II. The objective of the cruise was to begin documenting the biodiversity on and over the seamount, particularly of fishes, cephalopods, and crustaceans. Representatives of most species were preserved as vouchers for subsequent definitive identification. Preliminary identifications indicate the capture of 115 fish species. Among these were a number of new fish records for the area or rare species, including Acromycter pertubator (Congridae), Alepocephalus bairdii (Alepocephalidae), Mirognathus normani (Alepocephalidae), Bathygadus favosus (Bathygadidae), Nezumia longebarbata (Macrouridae), Gaidropsarus argentatus (Phycidae), and Dibranchus tremendus (Ogcocephalidae). Cephalopods comprised 26 species in 15 families, including one new distributional record and several rarely-collected species. The crustacean fauna was diverse with at least 46 species. Totals for other invertebrate species are pending laboratory identification, but number at least 113 species in 10 phyla. This includes a number of new distributional records and a new species of gorgonian.


Do regional assembly rules determine the structure of coral reef assemblages in the Indo-Pacific Ocean?

Camilo Mora,* Paul Chittaro, and Peter Sale. Biology Department, University of Windsor, 401 SUNSET Windsor-Ontario, N9B 3P4-Canada; e-mail [e-mail].

Throughout the history of ecology many interesting patterns have been found, but explaining them has often been a major challenge. A recently reported pattern among coral reefs of the Indo-Pacific is that the proportion of species among families is highly predictable, for both fishes and corals, based on the local pool of species. It has been suggested that such a pattern arises through the action of regional assembly rules in which life-history characteristics of the families influence the species composition in any coral reef assemblage. We tested the existence of assembly rules by comparing, for local species pools, the proportional distribution of species among families with output from a null model in which species were allocated randomly to Pseudo-families. We found that species richness in any family can predict very accurately the size of the local pool of species in any Indo-Pacific locality. However, equally speciose Pseudo-families yielded similar levels of predictability. Obviously, coral reef assemblages are extraordinarily ordered but since Pseudo-families also predict the local pool of species such order is unlikely due to any assembly rule imposed by families’ traits. How this pattern may arise randomly is discussed.


Hard clam (Mercenaria mercenaria) restocking efforts via larval injection: preliminary results on settlement success