Barkley Sound Research Articles

Conduction pathways in the nervous system ofSaccoglossussp. (Enteropneusta)

A species of Saccoglossus from Barkley Sound, British Columbia, was observed in the field and found to exhibit a startle withdrawal response. Optical and electron microscopy of the nerve cords failed to reveal giant axons. The dorsal collar cord and ventral trunk cord consist of small axons with a mean diameter of 0.4 μm. The majority of the axons run longitudinally and there is no indication of a specialized integrative centre. Electrical recordings from the nerve cords show events interpreted as compound action potentials. The potentials are through-conducted from proboscis to trunk. Such propagated events probably mediate startle withdrawal. Conduction velocities did not exceed 40 cm∙s−1in any part of the nervous system.

Spatial and temporal distributions of microplankton during the summers of 1992–1993 in Barkley Sound, British Columbia, with emphasis on harmful species

Spatial and temporal distributions of microplankton during the summers of 1992–1993 in Barkley Sound, British Columbia, with emphasis on harmful species

Characterizing temperate rocky shores from the perspective of an early juvenile snail: the main threats to survival of newly hatched Nucella emarginata

Mortality factors most likely to constitute substantial selective pressures for early juvenile gas- tropods on temperate rocky shores were identified by examining the vulnerability of hatchlings of an inter- tidal snail, Nucella emarginata, to heat stress, desicca- tion, and predation in 1992 and 1993. The highest temperature of substrata measured at tidal heights col- onized by N. emarginata in Barkley Sound, British Columbia, Canada, was 28.5 ~ This temperature was not lethal to hatchlings in laboratory tests. In labora- tory and field desiccation experiments, all hatchlings died within 6 h of emersion. Early juveniles could not survive direct exposure to even moderate drying condi- tions for the duration of a low tide. Hence, intertidal microhabitats which dry up even for short periods during low tides would prove lethal. Of 45 intertidal animal species to which hatchlings were exposed in the laboratory, small decapod crustaceans were the only organisms to cause substantial hatchling mortality. Of these, Pagurus hirsutiusculus and Hemigrapsus nudus were by far the most abundant in the field, and are probably the only important predators of early juvenile N. emarginata at most sites. Total predator densities in the field were as high as 438 individuals m-z, sugges- ting that predation pressure may be intense. Desicca- tion and predation by decapod crustaceans appear to be the most significant threats to early juvenile N. emarginata. These factors commonly occur on most temperate rocky shores and undoubtedly constitute major selective agents influencing population param- eters and shaping life-history strategies and early juvenile traits of intertidal invertebrates.

Morphology, Larval Development, and Distribution of Bathypera feminalba n. sp. (Ascidiacea: Pyuridae), a Deep-Water Ascidian from the Fjords and Sounds of British Columbia

A new species of the ascidian genus Bathypera (Ascidiacea: Pyuridae), B. feminalba, is described from deep-water habitats of Saanich Inlet and Barkley Sound, British Columbia, Canada, with data on the depth distribution, substratum use, reproduction, embryology, and larval development. The species is characterized by hourglass-shaped spicules topped with a single large spine and several smaller spines, a branchial sac with 7 folds per side, and irregular and curved stigmata. B. feminalba spawned in response to light following dark adaptation during the month of June. Development was similar to that of other pyurids. The tadpole larva, the first to be described in this genus, has the same sensory organs found in shallow-water relatives: an ocellus, a statocyst, and 3 large conical adhesive papillae. The ocellus is sensitive to monochromatic light between 475 and 600 nm with peak sensitivity in the blue region of the spectrum. This species occurs below 20-30 m depth, where it occupies vertical cliffs, the sides of boulders, and also smaller cobbles. It shares this habitat with a characteristic assemblage of ascidians, brachiopods, serpulid polychaetes, and sponges, few of which are found in shallow water. On a small scale, the distribution of B. feminalba is aggregated, with the pattern suggesting gregarious larval settlement. At the upper end of its depth range, this species appears to be excluded from surfaces with coralline algae; competition with algae or interactions with some organism associated with the coralline algal community may determine its upper limit. The coast of the northeastern Pacific between southern Alaska and central California has a diverse ascidian fauna of more than 80 known species (Austin 1985). Many species occurring in the intertidal and shallow subtidal zones have been studied extensively; indeed, some species from this region are among the best-known ascidians anywhere. However, the biology of ascidians living beyond scuba depths in this region remains virtually unknown. Between 1978 and 1984 we examined the ascidians of Saanich Inlet and Barkley Sound fjords, using a manned submersible, dredges, and scuba. We found a relatively sharp faunal transition: below about 30 m depth, most but not all of the shallow-water ascidians are replaced by a distinct ascidian assemblage with several previously undescribed or recently described species. This assemblage includes, besides the pyurid Bathypera feminalba n. sp. described in this paper, the pyurid Boltenia polyplacoderma recently described from 91-117 m depth off central California (Lambert 1993); an ascidiid, Rhopalaea cloneyi n. sp. (Vazquez & Young, unpubl.); the corellid Chelyosoma columbianum, which lives in deep water throughout the north Pacific; and the ascidiid Ascidia ceratodes, which defies the pattern predicted by equatorial submergence by living in shallower water in California than in British Columbia. A few species of ascidians characteristic of shallow subtidal habitats, notably Halocynthia igaboja, Styela coriacea, and Ascidia paratropa, also extend into deep water in British Columbia. Ascidians share the deep fjordic habitats with a fauna dominated by brachiopods (Tunnicliffe & Wilson 1988), galatheid crabs (Burd & Brinkhurst 1984), hexactinellid sponges, serpulid polychaetes, and cup corals (reviewed by Levings et al. 1983). The physical and biological factors that impose the upper limit of these organisms remain unknown, though low oxygen levels may determine their lower depth limit in fjords (Tunnicliffe 1981; Burd & Brinkhurst 1984). Ascidians of the genus Bathypera Michaelsen, 1904 are beautiful animals that resemble old-fashioned beaded purses. The beads are minute papillae arranged in a regular pattern and each containing a spiky calcareous spicule (Lowenstam 1989), often shaped like the acanthus-leaf decorations found atop Corinthian columns in ancient Greek architecture (Van Name 1945). The branchial sac has more than 4 plications on each side, and the stigmata are normally This content downloaded from 207.46.13.111 on Tue, 09 Aug 2016 04:49:15 UTC All use subject to http://about.jstor.org/terms

Distribution and dispersal of early juvenile snails:effectiveness of intertidal microhabitats as refuges and food sources

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 128:213-223 (1995) - doi:10.3354/meps128213 Distribution and dispersal of early juvenile snails: effectiveness of intertidal microhabitats as refuges and food sources Gosselin LA, Chia FS In Barkley Sound, British Columbia, Canada, newly hatched Nucellaemarginata, a direct developing prosobranch gastropod, are almost exclusively located within 3 structurally complex microhabitats: the filamentous algae Cladophoracolumbiana, clusters of mussels Mytilus spp., and dense assemblages of the barnacle Semibalanuscariosus. When exposed to desiccation or predators for 4 to 5 h, mortality of hatchlings located in these microhabitats (1.7 to 36% mortality) was considerably lower than for individuals on open surfaces (99 to 100%). Also, food (prey species) in C.columbiana, mussel clusters, and S. cariosus microhabitats was more abundant but of similar energetic value to that on open rock surfaces. The microhabitats used by early juvenile N.emarginata thus provide the double advantage of a considerably reduced risk of mortality and abundant prey. The means by which hatchlings disperse after emerging from their egg capsules were established by laboratory observations and by deployment of collectors in the field. Hatchlings do not actively initiate dispersal by drifting in the water column. Crawling is the usual means of travelling from the capsule to protective microhabitats, with hatchling crawling speed averaging only 3.7 mm min-1 on smooth rock surfaces in the laboratory. The abundance and distribution of microhabitats that protect early juveniles could therefore be important determinants of the local abundance and distribution of N.emarginata populations. The use of protective microhabitats may be the key to survival through the vulnerable early juvenile period in many benthic marine organisms. Mortality . Desiccation . Predation . Structural complexity . Drifting Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 128. Publication date: November 23, 1995 Print ISSN:0171-8630; Online ISSN:1616-1599 Copyright © 1995 Inter-Research.

Patterns of haemolymph-flow variation in decapod crustaceans

Adult male Dungeness crab, Cancer magister, were trapped in the Barkley Sound region of Vancouver Island, British Columbia during June 1992 to August 1993. Heart rate and haemolymph flow through the five major arterial systems were recorded in resting undisturbed C. magister using a pulsed Doppler flowmeter. This technique allowed calculation of the stroke volume of the heart as well as cardiac output. The heart rate of 62 C. magister conformed to a normal distribution, whereas haemolymph flow through individual arteries was exponentially distributed. Stable haemolymph flow through all arterial systems was observed in only about 5% of the individuals tested; more often, haemolymph flow in one or more arteries fluctuated independently of flow through the remaining arteries. Several typical patterns of variation in cardiovascular parameters are described and related to possible underlying control mechanisms.

Summer sea surface temperature variability off Vancouver Island from satellite data

Satellite‐sensed advanced very high resolution radiometer (AVHRR) sea surface temperature (SST) data over eight summers (1984–1991) were used to analyze the summer SST patterns of variability off the west coast of Vancouver Island. Empirical orthogonal function (EOF) analysis of the spatial variance for 133 nearly cloud‐free summer images was performed. The first EOF mode, which resembled the mean of all images, showed a strong cool water band located at the northwest corner of Vancouver Island, a cool tongue extending seaward from the Strait of Juan de Fuca and a warm patch off Barkley Sound. The second mode revealed topographically controlled upwelling: cool water over the shelf region with its seaward boundary roughly following the 200‐m depth contour, plus a cold eddy located just north of the Juan de Fuca Canyon. The third mode displayed cool water extending southwestward off Brooks Peninsula, while the fourth mode showed a cool water plume extending off Cape Scott at the northern tip of Vancouver Island. These four modes accounted for 33, 12, 10, and 5% of the SST variance, respectively. The temporal amplitude of these EOF modes revealed how the SST features changed as summer progressed. From these images, we also constructed an overall seasonal coolness index, which revealed the summers of 1986 and 1991 to have the coolest coastal water, with both summers immediately preceding an El Niño.

Downstream and Early Marine Migratory Behaviour of Sockeye Salmon (Oncorhynchus nerka) Smolts Entering Barkley Sound, Vancouver Island

Behaviour of sockeye salmon (Oncorhynchus nerka) smolts was studied during their migration down the Stamp and Somass rivers and through Alberni Inlet and Barkley Sound, Vancouver Island. Emigration from Great Central Lake was typical of other sockeye lakes: smolt abundance peaked in early May and most smolts left the lake at dusk. Migration down the rivers occurred only during twilight or darkness and most smolts made the 25-km journey to tidal waters within a single night. Those that did not held position in tight schools in the surface waters of deep pools during daylight. During downstream migration, ground speed averaged about 2.5 km/h, and smolts did not appear to be especially vulnerable to predation owing to their short residence time, with few smolts remaining in the river during daylight. Catch rates at purse-seine sampling sites throughout Alberni Inlet and Barkley Sound indicated that sockeye smolts migrated more slowly in tidal waters and were sometimes highly vulnerable to predaceous fish (especially Pacific hake, Merluccius productus). Estimated migration speeds through Alberni inlet were 1.9 km/d for smolts entering tidal waters during April and May, and 1.3 km/d for those during June and July; speed through Barkley Sound was 1.6 km/d throughout May–July.

Bottle appeal drifts across the Pacific

Pacific drift currents were used by a group of oceanographers to estimate the path of a drift bottle that was found on a beach of Barkley Sound in Vancouver Island by Richard Strickland on June 10, 1990. The Chinese rice wine bottle, which remained unopened until December 18, 1991, contained six leaflets, one appealing for the release of China's well‐known dissident, Wei Jingsheng. The bottle was one of thousands set adrift as part of a propaganda effort from the islands of Quemoy and Matsu off mainland China shortly after Wei was sentenced in 1979 to 15 years in prison (see Figure 1 for locations). Wei was in poor health and still in prison when the bottle made its way across the Pacific Ocean.

Tides and currents in Barkley sound and Alberni Inlet

Abstract A vertically integrated tidal model of Barkley Sound has been developed as the first phase of a study of circulation and its interaction with juvenile salmon moving through Alberni Inlet and Barkley Sound to the Pacific Ocean. This model is an implementation of the three‐dimensional baroclinic model GF8 using a single layer, with a horizontal grid size of 400 m. Elevations and velocity boundary condition data for this model were obtained from an irregular grid finite element model of the west coast of Vancouver Island. The resulting barotropic tidal model was found to be stable, and produced tidal elevations in close agreement with observations. Modeled tidal currents at the location of a current meter morred in Imperial Eagle Channel agreed well with observations, to the extent that barotropic currents could be deduced in a simple manner from observations containing both barotropic and baroclinic modes. The next phase in the modeling program was the development of an upper layer baroclinic model...

The role of sea anemones as refuges and feeding habitats for the temperate fish Oxylebius pictus

This study describes an association between the temperate zone fish Oxylebius pictus and sea anemones in Barkley Sound, Vancouver Island, British Columbia, Canada. Fish were observed swimming and resting unharmed among the tentacles, or next to a column of Urticina lofotensis (98% of all observations) and U. piscivora (2% of all observations). These associations were most commonly observed at moderately exposed sites where there were relatively high densities of O. pictus and anemones. Most associations occurred at night when the fish were inactive. Small young-of-year fish ( 12 cm total length) sheltered in rock holes and crevices. Experiments demonstrated that small O. pictus were more vulnerable to predators than large individuals. Urticina lofotensis and U. piscivora were large, persistent structures in the study habitats that provided effective refuge for O. pictus from predators. Anemone size, shape, tentacular adhesive force, and presence of copepod associates influenced patterns of host specificity. Oxylebius pictus fed on copepods and other crustaceans that associated with U. lofotensis and host sea anemones served as both refuges and feeding habitats for the fish. The sea anemones did not appear to receive any significant benefit from the relationship and the fish was considered to be a facultative commensal.

Integrated geophysical modelling of terranes and other structural features along the western Canadian margin

An integrated geophysical data set has been used to develop structural models across the continental margin west of Vancouver Island, Canada. A modern accretionary complex underlies the continental slope and shelf and rests against and below the allochthonous Crescent and Pacific Rim terranes. These terranes in turn abut against the pre-Tertiary Wrangellia terrane that constitutes most of the island. Gravity and magnetic anomaly data, constrained by seismic reflection, seismic refraction, and other data, were interpreted to determine the offshore positions of these terranes and related features. Iterative 2.5-dimensional forward models of anomaly profiles were stepped laterally along the margin to extend areal coverage over a 70 km wide swath oriented normal to the tectonic features. An average model was then developed to represent this part of the margin. The Pacific Rim terrane appears to be continuous and close to the coastline along the length of Vancouver Island, consistent with emplacement by strike-slip motion along the margin. The Westcoast fault, the boundary between the Pacific Rim and Wrangellia terranes, is interpreted to be 15 km farther seaward than in previous interpretations in the region of Barkley Sound. The Crescent terrane forms a thin landward-dipping slab along the southern half of the Vancouver Island margin, and cannot be confirmed along the northern part. Model results suggest the slab has buckled into an anticline beneath southern Vancouver Island and Juan de Fuca Strait, uplifting high-density lower crustal or upper mantle material close to the surface to produce the observed intense positive gravity anomaly. This geometry is consistent with emplacement of the Crescent terrane by oblique subduction.

Benthic biology of the western Canadian continental shelf

Quantitative benthic studies on the British Columbian continental shelf are virtually non-existent. This paper attempts to review the inadequate data available. Sand and mud substrata on the western Canadian continental shelf of British Columbia off Barkley Sound support equally diverse benthic infaunal associations. Of the 282 taxa found in grab samples 142 were unique to this study, 42 were also present at other deep water sites, and 32 were ubiquitous. Organic carbon and nitrogen values were lower in sandy substrata than in mud. Reduced oxygen values in deep water resulting from a barotropic eddy present during the summer appear to be responsible for significant differences in the faunal associations between cruises in contrast to the community stability observed in other locations.

Oviposition, larval abundance, in situ larval growth and recruitment of the herbivorous gastropodLacuna vincta in kelp canopies in Barkley Sound, Vancouver Island (British Columbia)

We investigated recruitment of the herbivorous gastropodLacuna vincta (Montagu, 1803) in the canopies ofMacrocystis integrifolia andNereocystis luetkeana beds in Barkley Sound, Vancouver Island (British Colombia), from 1987 to 1989. Four factors influencing intensity and patterns of recruitment were studied: (1) seasonality of oviposition, (2) larval abundance, (3) growth of larvae in the field and (4) larval settlement. Egg masses were abundant on low intertidal algae but were scarce in kelp canopies. Although egg masses could be found almost year-round, a distinct and intense period of oviposition occurred during winter and spring. Intracapsular development lasted 2.5 to 3.5 wk before planktotrophic veligers emerged. The duration of the planktonic period, 7 to 9 wk, was determined through an in situ study of cohorts ofLacuna spp. larvae present in the plankton between January and June 1988. The general timing of the onset of the spring peak recruitment period was predicted from these cohorts. Primary periods of recruitment ofL. vincta in the canopy occurred in April–May (average density up to 383.9 juveniles m−2 blades), with a second period of lower intensity in the late summer—fall period. We observed similar trends between abundance of advanced larvae (> 500µm) in the plankton and recruitment rates in kelp canopies. Although adults were occasionally observed in the canopy, newly metamorphosed juveniles consistently dominated the habitat. The persistance of small juveniles (0.7 to 1.5 mm), rapid declines in density shortly after recruitment, and SCUBA observations of drifting individuals suggest that juveniles migrate to the under-canopy or low intertidal area after a brief period of growth on kelp blades.

Stable Isotope Analysis of Marbled Murrelets: Evidence for Freshwater Feeding and Determination of Trophic Level

Stable carbon and nitrogen isotopic analyses were performed on tissues of 21 Marbled Murrelets (Brachyramphus marmoratus) collected in Barkley Sound (n = 18) and on Johnston Lake, British Columbia (n = 3). Three adult males had significantly lower muscle tissue 613C values (x ? SD: -23 ? 2.7%0, n = 3) than did all other murrelets (16.5 ? 0.6%0, n = 18). Based on a model predicting muscle 6'3C values for murrelets feeding on freshwater and marine prey these three individuals had short-term freshwater-derived protein inputs to their diets ranging from 50 to 100%. The mean 613C value for Marbled Murrelet bone collagen (-16.8 ? 0.3%0, n = 4) was not significantly different from that found for Ancient Murrelets (Synthliboramphus antiquus) from Reef Island, Queen Charlotte Islands. This suggests that while some Marbled Murrelets may feed exclusively on freshwater prey for a short but important period of several weeks, freshwater protein is not a significant long-term dietary component in their diets. Marbled Murrelets had a mean muscle s5N value of 15.3 ? 0.7%0 (n = 21). Because 6' N values for freshwater and marine prey species overlapped significantly, stable-nitrogen isotope analysis did not distinguish between Marbled Murrelets feeding on freshwater or marine prey. The stable-nitrogen isotope values of muscle tissue from Marbled Murrelets were compared with those of nine other species of alcids from British Columbia and the high Arctic. The comparison indicates that stablenitrogen isotope analysis is potentially useful for establishing trophic relationships in seabird communities.

Soft-Bodied Zooplankton Predators and Competitors of Larval Herring (Clupea harengus pallasi) at Herring Spawning Grounds in British Columbia

The soft-bodied zooplankton predators and the microzooplankton foods of herring larvae were collected at 28 herring spawning grounds in British Columbia in April 1984, when herring larvae (Clupea harengus pallasi) hatched. The same predator species were found throughout coastal B.C., but total densities varied over three orders of magnitude. Barkley Sound had the highest densities, and bays in northern B.C. and the Strait of Georgia had higher densities than open shorelines in both regions. Eight of 18 species of soft-bodied predators contained herring larvae. The hydromedusan Aequorea victoria was the most important predator, and consumed 0.4% of the herring larvae∙d−1 in Fanny Bay, and 12.5, 3.9, and 0%∙d−1 over three consecutive days in Kulleet Bay as larval densities decreased. Herring larvae ate copepod nauplii (84.4%) and other microzooplankton. Densities of these prey varied between 0.8 and 37∙L−1 among 21 locations sampled. Only three species of hydromedusae showed extensive dietary overlap (90–100%) with larval herring. Soft-bodied predators consumed < 1%∙d−1 of the microzooplankton in 17 locations, and could have affected densities in only one of the 21 locations. The ratios of microzooplankton to predator densities varied over 1000-fold, suggesting great differences in the chances for herring larval survival among various locations.

The ecology of beach-dwelling Peromyscus maniculatus on the Pacific Coast

Live- and snap-trapped Peromyscus maniculatus from Barkley Sound, B.C., were compared between beach and inland habitats as well as between island and mainland populations. Densities, as indicated by trapping success, were not consistently different between beach and inland habitats, although the islands appeared to be more densely populated than the mainland. Mice in beach and inland habitats showed fidelity to those sites. Pregnancy rates were higher in beach habitats than in inland habitats. Beach mice were also larger, but less fat, than inland mice. We suggest that future comparisons between island and mainland populations take into consideration the variance in demographic and morphological parameters within, as well as among, islands.

Nesting Population, Nest Sites, and Prey Remains of Bald Eagles in Barkley Sound, British Columbia

In 1988, the nesting population of bald eagles (Haliaeetus leucocephalus) in Barkley Sound, British Columbia was surveyed, and both the nesting habitat and the prey of these birds were investigated. Fifty-four occupied nesting territories were observed. Linear nest densities on forested islands in Barkley Sound averaged 0.11 nest/km of shoreline, and those along the perimeter of Vancouver Island in the Sound averaged 0.07 nests/km of shoreline. The number of eagles was similar to the number observed 15-17 years earlier by Retfalvi (1977). Of 80 prey remains found beneath nesting trees of eagles, birds constituted 41.2%, marine invertebrates 45.0S, fishes 10.0%, and mammals 3.8% of the identified items. The glaucous-winged gull (Larus glaucescens) was the most frequent prey species (28.3%) in the remains. Eagles also were observed to feed on herring spawn in March. The proportion of islands with nests was higher for large (>0.005 km2) islands than for smaller ones. Nests were found mostly in red cedar (Thuja plicata), but also in western hemlock (Tsuga heterophylla), sitka spruce (Picea sitchensis) and Douglas-fir trees (Pseudotsuga menziesii), at an average height of 30.3 + 13.3 m above ground. The distance of nests from shore averaged 37 + 21 m. The purposes of this study were a) to assess the size of the present population of bald eagles throughout Barkley Sound, British Columbia, b) to determine which islands and sites these eagles selected for nesting, c) to identify prey remains of eagles beneath nests, and d) to compare the population density, nest site seleciton and prey of the Barkley Sound population with those of eagles nesting in the Gulf Islands, British Columbia. This latter population was investigated in 1987 by Vermeer et al. (1989) using the same methods as in this study.

Population size-structure, juvenile growth, and breeding periodicity of the sea star Asterina miniata in Barkley Sound, British Columbia

Populations of Astenna rniniata (Brandt, 1835) exhibited a heterogeneous spatial pattern of recruitment in 2 adjacent estuarine inlets in Barkley Sound, British Colun~bia. Two distinct cohorts of juvenlles occurred in Grappler Inlet, while juveniles were absent nearby in Bamfield Inlet. The breedmg period~city of adults, field observations of spawning, and rates of juvenile growth suggest that larvae settled in Grappler Inlet during summer 1983 and 1984. Surveys of populations In subsequent years lndlcate that no recruitment occurred in Bamfleld or Grappler Inlet in 1985 to 1987. Survivorship of juvenlles was hlgh in laboratory experiments that assessed predation by 7 species of macroinvertebrates and 1 carnivorous fish Low densities of A. rniniata outslde Grappler Inlet, coupled with slow crawling speeds, suggest that the appearance of juvenlles in Grappler Inlet was probably due to autochthonous settlement. Patterns of recruitment of A. rniniata are affected primarily by complex Interactions between pre-settlement and early post-settlement events rather than migratory movements or juvenile mortality.

Simultaneous Spawning of Six Species of Echinoderms in Barkley Sound, British Columbia

Summary Six species of echinoderms were observed spawning (1 holothuroid, 1 echinoid, 4 asteroids) during a single 40 min dive to 10 to 18 m depth in Barkley Sound, Vancouver Island, on the afternoon of 9 August 1987, the day after the full moon. Most of the spawning animals were not close to conspecific individuals. None were observed spawning the following day. Published reports indicate that it is not uncommon for widely scattered individuals of echinoderms to broadcast spawn in the field. Fertilization success often may be low. Moreover, simultaneous spawning by different species, as we and others have observed, indicates that the incidence of hybridization (either lethal or viable) could be high and have important consequences to the biology of the species involved.