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Kelletia kelletii (Forbes, 1850) is an intertidal to subtidal marine buccinid gastropod with a range from California, USA, to Baja California, Mexico. Many characteristics of its mating behavior, general life history, and larval biology are known, but details about its larval morphology and behavior are lacking. Here, aspects of its larval development and morphology during early ontogeny are chronicled, including larval velar form and function, asymmetrical development, particle ingestion, larval yolk reserves, and larval shell morphology. Snail oviposition behavior was observed in aquaria and egg capsules were dissected at different stages of development and examined under optical and scanning electron microscopy. Egg capsules had undeveloped eggs and/or embryos that were not ingested by K. kelletii larvae. Hatching time (natural excapsulation) varied between 37 to 55 d depending on water conditions, and endogenous yolk reserves were present in most veligers at capsule emergence. Pre-hatching veligers could swim in the plankton if excapsulated at 27 d and had symmetrical velar lobes but different sized cephalic tentacles. At 2.5 weeks in the plankton, both cephalic tentacles and velar lobes were asymmetrical, with those on the larvae’s right larger than those on their left. Larval shells were brittle and poorly mineralized at excapsulation but fully mineralized with an apertural beak and proto-siphonal canal by 2.5 weeks in the plankton. Particle capture and transport through the velar lobes to the mouth was possible in pre-hatching veligers, but ingestion only occurred in emerged veligers when yolk stores were depleted. Chronicling early ontogeny and its sequence, as in this study, is essential to the understanding of larval development and its evolution in gastropods, and to comparative studies of larval biology in the Buccinidae.

OEG was supported by MASTS (the Marine Alliance for Science and Technology for Scotland). Accurately estimating patterns of population connectivity in marine systems remains an elusive goal. Current genetic approaches have focused on assigning individuals back to their natal populations using one of two methods: parentage analyses and assignment tests. Each of these approaches has their relative merits and weaknesses. Here, we illustrate these tradeoffs using a forward-time agent-based model that incorporates relevant natural history and physical oceanography for 135 Kellet’s whelk (Kelletia kelletii) populations from Southern California. Like most marine organisms, Kellet’s whelks live in large metapopulations where local populations are connected by dispersive larvae. For estimating population connectivity, we found parentage analyses to be relatively insensitive to the amount of genetic differentiation among local populations, but highly sensitive to the proportion of the metapopulation sampled. Assignment tests, on the other hand, were relatively insensitive to the proportion of the metapopulation sampled, but highly sensitive to the amount of genetic differentiation found among local populations. Comparisons between the true connectivity matrices (generated by using the true origin of all sampled individuals) and those obtained via parentage analyses and assignment tests reveal that neither approach can explain more than 26% of the variation in true connectivity. Furthermore, even with perfect assignment of all sampled individuals, sampling error alone can introduce noise into the estimated population connectivity matrix. Future work should aim to improve the number of correct assignments without the expense of additional incorrect assignments, perhaps by using dispersal information gleaned from related individuals as priors in a Bayesian framework. These analyses dispel a number of common misconceptions in the field and highlight areas for both future research and methodological improvements. Postprint

Field experiments were performed to explore the nature of indirect inter- actions between two groups of ecologically distinct prey that occur on subtidal rocky reefs at Santa Catalina Island, California. Mobile gastropods (Tegula aureotincta, Tegula eiseni, and Astraea undosa) and sessile bivalves (mostly Chama arcana) share a common set of invertebrate predators (lobster Panulirus interruptus, cephalopod Octopus bimaculatus, and whelk Kelletia kelletii). The gastropods, which are secondarily preferred prey, principally occur on cobble reefs and less commonly on high-relief boulder reefs. Sessile bivalves and other species of favored prey are common on high-relief reefs and are rare or absent in cobble areas. The density of each predator species is greatest in high-relief areas containing abundant favored prey. Addition of bivalves to replicate cobble plots resulted in marked increases in predator density, relative to controls, because predators aggregated to areas containing favored prey. Greater densities of predators in the presence of experimentally added bivalves resulted in greater mortality and lower population densities of gastropods relative to controls. Conversely, mortality of Chama was higher where gastropods were common compared with cobble areas containing fewer gastropods. This occurred because the density of pred- ators within a cobble reef, although low overall, was positively correlated with density of gastropods. Thus each group of prey was negatively affected by the presence of the other because each alternative prey increased the local density of predators. Such a doubly negative indirect interaction between prey, mediated by a shared predator, is known as "apparent competition"; this is the first experimental demonstration of its existence. Be- cause gastropods and bivalves are superior at withstanding predation in different habitats, shared predation and apparent competition may be sufficient mechanisms to maintain the pattern of habitat segregation displayed by these prey groups.

Marine species frequently show weak and ⁄or complex genetic structuring that is commonly dismissed as ‘chaotic’ genetic patchiness and ecologically uninformative. Here, using three datasets that individually feature weak chaotic patchiness, we demonstrate that combining inferences across species and incorporating environmental data can greatly improve the predictive value of marine population genetics studies on small spatial scales. Significant correlations in genetic patterns of microsatellite markers among three species, kelp bass Paralabrax clathratus, Kellet’s whelk Kelletia kelletii and California spiny lobster Panulirus interruptus, in the Southern California Bight suggest that slight differences in diversity and pairwise differentiation across sampling sites are not simply noise or chaotic patchiness, but are ecologically meaningful. To test whether interspecies correlations potentially result from shared environmental drivers of genetic patterns, we assembled data on kelp bed size, sea surface temperature and estimates of site-to-site migration probability derived from a high resolution multi-year ocean circulation model. These data served as predictor variables in linear models of genetic diversity and linear mixed models of genetic differentiation that were assessed with information–theoretic model selection. Kelp was the most informative predictor of genetics for all three species, but ocean circulation also played a minor role for kelp bass. The shared patterns suggest a single spatial marine management strategy may effectively protect genetic diversity of multiple species. This study demonstrates the power of environmental and ecological data to shed light on weak genetic patterns and highlights the need for future focus on a mechanistic understanding of the links between oceanography, ecology and genetic structure.

Elemental signatures have been used as a tool to track individual organisms to their natal site in an attempt to understand stock structure and larval dispersal. However, factors that affect elemental signatures are not well understood. We conducted a factorial experiment using whelk Kel- letia kelletii larvae from Salta Verde Point on Catalina Island, Los Angeles Harbor, and White Point, Palos Verdes peninsula, California, USA, to test the effects of egg source, temperature (10, 14 and 18°C) and culture seawater on the elemental composition of larval statoliths. Intra-capsular contents of newly laid capsules were also analyzed to explore whether maternal contributions might affect lar- val statolith chemistry. Using inductively coupled plasma mass spectrometry we quantified ratios of 7 elements to calcium in both intra-capsular contents and cultured statoliths and provided the first evidence of significant egg-source effects, independent of subsequently experienced environmental conditions, on statolith elemental signatures for Mg:Ca, Ba:Ca and Pb:Ca. Intra-capsular and statolith element ratios showed no clear relationship that might have indicated possible maternal transfer of elements to larvae. Culture seawater elemental concentration was positively related to statolith Ba:Ca and Pb:Ca, and temperature was negatively related to statolith Sr:Ca, Ba:Ca and Pb:Ca, while no significant effects were found for Mn:Ca or Zn:Ca. Effect-size estimates show that elements responded differently to factors within the variation measured in this study; the major effects for Ba and Pb were temperature and egg source, respectively. The significant effect of egg source on elemental signatures has potentially important implications for tracking free-spawned larvae.

Trace elements in larval hard parts may serve as useful tags of natal origin in inverte- brate population studies. Using field-collected encapsulated veliger larvae of the marine gastropod Kelletia kelletii, this study examined the extent of spatial and temporal variation in the elemental composition of larval parts formed at the natal source. For both protoconchs and statoliths, results of multivariate analyses of variance (MANOVA) indicated that the elemental compositions show signif- icant among-site and among-region differences. Linear discriminant-function analysis (DFA) cor- rectly classified 89% of protoconchs and 80% of statoliths to their region of formation. However, there were significant interannual differences in elemental composition for statoliths at 2 sites and for protoconchs at 3 sites over a 3 yr period. Despite within-site interannual differences, the elemental compositions of hard parts formed during different years resembled one another to such a degree that a DFA generated with a single year's data could correctly predict the region of formation for 83.9% of statoliths and 82.5% of protoconchs formed in other years. A comparison of magnesium (Mg), strontium (Sr) and barium (Ba) incorporation patterns with per-site temperature profiles indicated statistically significant positive relationships between temperature and Mg and Sr incorporation into protoconchs, and inverse relationships between temperature and Sr (statoliths) and Ba (both proto- conchs and statoliths) incorporation. These data, together with results from other studies, suggest that larval statoliths and protoconchs can meaningfully record variation in the physical and chemical properties of seawater and, hence, have potential as natural tags of natal origin.

The trace elemental composition of calcified larval hard parts may serve as useful tags of natal origin for invertebrate population studies. We examine whether the trace metal barium (Ba) deposits into the calcium carbonate matrix of molluscan larval statolith and protoconch in proportion to seawater Ba concen- tration at two temperatures (11.5 and 17°C). We also examine strontium (Sr) uptake as a function of temperature. Using encapsulated larvae of the marine gastropod, Kelletia kelletii, reared in the laboratory under controlled conditions, we demonstrate a significant inverse effect of temperature and a positive effect of seawater Ba/Ca ratio on Ba incorporation into larval carbonates. Ba/Ca partition coefficients ( DBa )i n protoconch were 1.13 at 11.4°C and 0.88 at 17.1°C, while DBa in larval statolith measured 1.58 at 11.4°C and 1.29 at 17.1°C. Strontium incorporation into statoliths is also inversely affected by temperature, but there was a significant positive effect of temperature on Sr incorporation into protoconch. These data suggest larval statoliths and protoconchs can meaningfully record variation in seawater physical and chemical properties, and, hence, have potential as natural tags of natal origin. Copyright © 2003 Elsevier Ltd

Aim The development of accurate models predicting species range shifts in response to climate change requires studies on the population biology of species whose distributional limits are in the process of shifting. We examine the population biology of an example system using the recent northward range expansion of the marine neogastropod Kelletia kelletii (Forbes, 1852). Location This is a marine coastal shelf neogastropod species whose range extends from Isla Asuncion (Baja California, Mexico) to Monterey (CA, USA). Research sites spanned the extent of the range. Methods We examine abundance distributions and size frequency distributions of K. kelletii for evidence of factors determining historic and contemporary distributional patterns. Population studies were supplemented by historic and contemporary hydrographic data, including seawater temperature data from California Cooperative Oceanic Fisheries Investigations (CalCOFI ) and National Data Buoy Center (NDBC), and seawater circulation data. Results The structure of recently established populations varied dramatically from that of historic populations. Markedly low densities and irregular size frequency distributions characterized recently established populations and suggested only occasionally successful recruitment. The point of transition between historic and recently established populations also corresponded to the location of a gradient in seawater temperature and the confluence of two major oceanic currents. The accumulated data suggest that temperature and/or barriers to dispersal could have set both contemporary patterns in population structure as well as the former northern range limit. Main conclusions Early life stages play a critical role in determining distributional patterns of K. kelletii. Dispersal barriers and temperature limitation are two plausible mechanisms that could determine both contemporary and historic distributional patterns. Future studies on this species should attempt to tease apart the relative importance of these factors in maintaining the populations at the northern edge of the range.

There is considerable interest in the genetic structure of Kelletia kelletii because of its economic, ecological and scientific importance. To that end, we developed species-specific primers which amplify mitochondrial cytochrome c oxidase subunit I as well as 13 hypervariable nuclear microsatellite loci. Using dye-labelled primers, the microsatellite loci can be co-amplified in two multiplex polymerase chain reactions and scored simultaneously on an automated sequencer.

Documenting larval behavior is critical for building an understanding of larval dispersal dynamics and resultant population connectivity. Nocturnal diel vertical migration (DVM), a daily migration towards the surface of the water column at night and downward during the day, can profoundly influence dispersal outcomes. Via laboratory experiments we investigated whether marine gastropodKelletia kelletiilarvae undergo nocturnal DVM and whether the behavior was influenced by the presence of light, ontogeny, and laboratory culturing column height. Larvae exhibited a daily migration pattern consistent with nocturnal diel vertical migration with lower average vertical positioning (ZCM) during day-time hours and higher vertical positioning at night-time hours. ZCM patterns varied throughout ontogeny; larvae became more demersal as they approached competency. There was no effect of column height on larval ZCM. DVM behavior persisted in the absence of light, indicating a possible endogenous rhythm. Findings from field plankton tows corroborated laboratory nocturnal DVM findings; significantly moreK.kelletiiwere found in surface waters at midnight compared to at noon. Unraveling the timing of and the cues initiating DVM behavior inK.kelletiilarvae can help build predictive models of dispersal outcomes for this emerging fishery species.

The interaction between the preferences of predators and defenses of prey and the role it plays in shaping distribution and abundance patterns of two gastropod species in a subtidal marine community were investigated. The snails, Tegula eiseni and T. aureotincta, are patchily distributed on horizontal rocky substrata at depths of 2-10 m off Santa Catalina Island, California, USA. The dominant invertebrate predators in these habitats are the sea stars Pisaster giganteus and Astrometis sertulifera, the whelk Kelletia kelletii, the cephalopod Octopus bimaculatus, and the lobster Panulirus interruptus. Their preferred prey include sea urchins, crabs, and sessile bivalves; the Tegula species are less-favored prey. A positive correlation was found between the abundance of the five predators and that of their preferred nongastropod prey. A negative association was detected between predator density and abundance of all motile gastropods, prey that tend to rank lower on the preference hierarchies of the predators. The two most common snail species were the Tegula congeners, which comprise 83% of the gastropod group by number. The spatial distributions of the two Tegula species are not identical. T. eiseni, but not T. aureotincta, is abundant in areas supporting moderate densities of predators. Both species are rare in habitats with high predator densities, and are common where few predators occur. The two Tegula species are known to have defenses against predation that differ from one another. T. aureotincta displays a flight behavior in the presence of Pisaster, Astrometis, and Kelletia. No such reaction is elicited when the snail is exposed to rapidly moving "unavoidable" predators such as Octopus and Panulirus. T. eiseni does not employ flight defenses, but instead has morphological features that reduce its acceptability as food. Such features are not characteristic of T. aureotincta. These differences in defense probably account for the marked preference for T. aureotincta over T. eiseni by invertebrate predators. Field experiments involving predator and prey manipulations on patch reefs indicate that both emigration and death by predation account for the lack of T. aureotincta in areas with high and intermediate densities of predators. As a consequence of its relatively more effective defense, T. eiseni can persist in habitats that contain moderate numbers of predators. The absence of T. eiseni in high predator density areas is the result of direct predation. The dissimilarity in defense mechanisms of the snails accounts for the observed difference in distribution and abundance of the Tegula species. Further, the distribution of predators is correlated with that of their preferred prey. The defenses of the favored prey appear superior to those of motile gastropods, and, as a consequence, the less- preferred gastropod prey are heavily consumed when they occur in the same areas. Although there might be little direct interaction between prey groups, the spatial distribution of preferred prey can thus influence the distribution and abundance of motile gastropods.