Sand Crab Emerita Analoga Research Articles

El Niño Range Extensions of Pacific Sand Crab (Emerita analoga) in the Northeastern Pacific

Many marine species are shifting poleward with global climate change, and many move on a shorter-term basis with periodic climate variations such as the El Nino Southern Oscillation (ENSO) and Pacific Decadal Oscillation (PDO). The Pacific sand crab Emerita analoga (Crustacea: Decapoda: Anomura: Hippidae) is a dominant member of the wave-exposed sandy beach macrofauna of California and Oregon. Its occasional records from Washington to Alaska have been taken to correspond to ENSO events. However, there are surprisingly few scientific or citizen-science records of its presence in this region. We report the first published record in over 30 years of E. analoga in British Columbia, and summarize historical published and unpublished records. Because this species is conspicuous and readily identifiable, we suggest the general absence of its published, institutional, and citizen-science records coincident with most historical ENSO events may be due to a lack of reporting. In California, E. analoga accumulates harmful algal bloom toxins, is consumed by crabs, fish, birds, and marine and terrestrial mammals, and serves as the intermediate host for a variety of parasites, including the peritonitis-inducing acanthocephalan implicated in sea otter mortalities. As coastal waters warm, we predict that E. analoga will colonize sandy beaches north of its current range, where it may serve as an abundant prey item and as a vector for the trophic transfer of toxins and parasites. Detecting changes in its abundance will require the continued observation and reporting of its records, which we encourage in academic, government, and citizen-science venues.

New host record for the California mussel Mytilus californianus (Bivalvia, Mytilidae), epibiotic on the Pacific sand crab Emerita analoga (Decapoda, Hippidae) from Monterey Bay, California (U.S.A.)

Sea mussels form dense aggregations on temperate rocky shores; however, in the absence of such firm substrates, biogenic surface such as the calcified integument of crustaceans may become settlement sites for their larvae. In this paper we present the first report on the association between the California mussel Mytilus californianus Conrad, 1837 and the Pacific sand crab Emerita analoga (Stimpson, 1857), collected from a sandy beach in Monterey Bay, California, U.S.A. We examined 63 crabs, and three had epibiotic mussels attached on their lateroventral surfaces. The organisms were measured and photographed. Such low incidence rate is tied to the collection site, as sandy beaches are considered atypical habitats for this bivalve species. The occurrence of epibiotic M. californianus suggests a random and non-obligatory relationship with E. analoga.

Body shape and burial behavior of the sand crab Emerita analoga (Stimpson 1857) in a reflective to intermediate morphodynamic range of sandy beaches

Sand crabs belonging to the genus Emerita are the dominant species on sandy beaches of the Pacific and Atlantic coasts of America. The success of this genus has been attributed to the great phenotypic plasticity of life history traits that enables them to cope with swash climate variability from beach to beach. The burrowing rate and variation in carapace shape of Emerita analoga from south-central Chile were studied on a series of five sandy beaches with contrasting reflective-intermediate swash conditions (harsher swash to benign swash). Environmental sampling was carried out monthly from September 2009 to November 2010, while biological experiments were conducted in September and October 2010. A combination of field experiments, geometric morphometric tools and multivariate analysis was used to assess the relationship between burrowing behavior and carapace shape with variables of swash climate. Our results showed that (1) body shape of E. analoga is directly affected by the frequency of effluent line crossing, (2) burrowing rate of E. analoga is affected directly by shape variability, (3) burrowing rate is affected directly and indirectly by the swash climate variables: frequency of effluent line crossing and mean grain size of sediment. Thus, the physical conditions in the intertidal zone may be the main environmental constraints determining cephalothorax shape, with a wider cephalothorax on beaches with finer sand and more benign physical dynamics, and a narrower shape on beaches with coarser sand and harsher physical dynamics. The latter phenotype (narrower shape) probably allows compensating the high difficulty of burying in coarser sediments.

The influence of environmental factors on the abundance and recruitment of the sand crab Emerita analoga (Stimpson 1857): Source–sink dynamics?

The sandcrab Emerita analoga is the dominant species inhabiting sandy beaches along the Pacific coast of the American continent. In our study, 10 sandy beaches were sampled seasonally from 2006 to 2011, including coastal planktonic sampling from 2006 to 2008. Two major population cores were detected, the first one in the northern part of the study area and the second in the area immediately to the south of the Itata River mouth. Zoeal stages were found along the entire coastal zone. Highest densities and recruitment were found during spring and summer of each year. PLS regression indicated that source–sink habitat proxies correlated positively with morphodynamic parameters; while beach slope and total organic matter were negatively correlated. These results agree with the source–sink hypothesis, finding higher densities of adults, recruits and cohort recurrence on open coast beaches with milder physical dynamics. Furthermore, a hypoxic event and a mega-earthquake/tsunami negatively affected recruitment at the inter-annual scale.

Spatial variability of recruitment in the sand crab Emerita analoga throughout California in relation to wind-driven currents

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 350:1-17 (2007) - DOI: https://doi.org/10.3354/meps07208 Spatial variability of recruitment in the sand crab Emerita analoga throughout California in relation to wind-driven currents Jennifer M. Diehl1, Robert J. Toonen2,*, Louis W. Botsford1 1Department of Wildlife, Fish and Conservation Biology, University of California, Davis, California 95616, USA 2School of Ocean and Earth Science and Technology, The Hawai’i Institute of Marine Biology, University of Hawai’i at Manoa, Coconut Island, PO Box 1346, Kane’ohe, Hawai’i 96744, USA *Corresponding author. Email: toonen@hawaii.edu ABSTRACT: We compared recruitment of the sand crab Emerita analoga over 2 yr at 17 sites distributed along >800 km of the California coastline. We hypothesized that larvae of benthic invertebrates are retained by water circulation near headlands, and then redistributed alongshore north of the promontories during synoptic-scale relaxation in upwelling winds. We tested for a negative relationship between recruitment and distance north of 4 headlands: Point Arena, Point Reyes, Monterey Peninsula, and Point Conception. We also examined patterns of recruitment at sites east of Point Conception, within the Southern California Bight (SCB). Recruitment magnitude was predictable at a given site within a recruitment season (June through October), but not between the 2 years at each site. Recruitment of E. analoga north of Point Conception was negatively correlated with site distance north of a headland in 1998, but not in 1999. Upwelling indices in 1998 were not significantly different from the long-term average either north of Point Conception or within the SCB; in contrast, during 1999, upwelling was stronger than the 54 yr average at all sites north of Point Conception, but not at those within the SCB. Thus, the upwelling-relaxation mechanism appeared to operate effectively from Point Arena to Point Conception in 1998, when upwelling and wind stress were within long-term average levels, but not in 1999, when upwelling and wind stress were anomalously high. However, in the SCB, we observed similar magnitude and spatial patterns of recruitment in both years. One implication of our results is that the California coast may be composed of separate retentive cells of populations separated by headlands, which enhances population persistence, but the extent of larval loss from these cells remains unknown. KEY WORDS: Upwelling · Relaxation · Wind stress · Inner shelf · Larval transport · Settlement Full text in pdf format NextCite this article as: Diehl JM, Toonen RJ, Botsford LW (2007) Spatial variability of recruitment in the sand crab Emerita analoga throughout California in relation to wind-driven currents. Mar Ecol Prog Ser 350:1-17. https://doi.org/10.3354/meps07208Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 350. Online publication date: November 22, 2007 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2007 Inter-Research.

First record of an epibiosis between the sand crab Emerita analoga (Stimpson, 1857) (Decapoda: Hippidae) and the mussel Semimytilus algosus (Gould, 1850) (Bivalvia, Mytilidae) in southern Peru

Coastal zones of the Humboldt Current Upwelling System (HCUS) are composed both of rocky and sandy beaches inhabited by macrozoobenthic communities. These show oscillating changes in the dominance of species; the abundance of the sand crab Emerita analoga is linked to phases of the El Niño Southern Oscillation (ENSO). The biogenic surfaces of these crabs serve as substrate for opportunistic colonizers. This study is the first record of an epibiosis between E. analoga and the rock mussel Semimytilus algosus, detected at a southern Peruvian sandy beach. Mussels fouled a wide size-range of adult E. analoga (7.3%) but they themselves belonged to small-size classes. The largest S. algosus was 17.4 mm in length. Highest permanence of epibionts was found on larger sand crabs (maximum between 24 and 27 mm). Significantly more mussels were found on the ventral surface (39.4%) compared to 10 other surface areas of the sand crab. Possible benefits and disadvantages of the observed epibiosis for both the basibiont and the epibiont are discussed.

Copper acute toxicity tests with the sand crab Emerita analoga (Decapoda: Hippidae): a biomonitor of heavy metal pollution in Chilean coastal seawater?

Copper acute toxicity tests with the sand crab Emerita analoga (Decapoda: Hippidae): a biomonitor of heavy metal pollution in Chilean coastal seawater?

Receptor potentials and electrical properties of nonspiking stretch-receptive neurons in the sand crab Emerita analoga (Anomura, Hippidae).

Receptor potentials and electrical properties of nonspiking stretch-receptive neurons in the sand crab Emerita analoga (Anomura, Hippidae). Four nonspiking, monopolar neurons with central somata and large peripheral dendrites constitute the sole innervation of the telson-uropod elastic strand stretch receptor in Emerita analoga. We characterized their responses to stretch and current injection, using two-electrode current clamp, in intact cells and in two types of isolated peripheral dendritic segments, one that included and one that excluded the dendritic termini (mechanosensory membrane). The membrane potentials of intact cells at rest (mean +/- SD: -57 +/- 4. 4 mV, n = 30), recorded in peripheral or neuropil processes, are similar to the membrane potentials of isolated dendritic segments and always less negative than membrane potentials of motoneurons and interneurons recorded in the same preparations. Ion substitution experiments indicate that the membrane potential is influenced strongly by Na+ conductance, probably localized in the mechanotransducing terminals within the elastic strand. The form of the receptor potential in response to ramp-hold-release stretch remains the same as stretch amplitude is varied and is not dependent on initial membrane potential (-70 to -30 mV) or recording site: initial depolarization (slope follows ramp of applied stretch), terminated by rapid, partial repolarization to a plateau (delayed depolarization) that is intermediate between the peak depolarization and the initial potential and sustained for the duration of the stretch. Responses to depolarizing current pulses are similar to stretch-evoked receptor potentials, except for small amplitude stimuli: an initial peak occurs only in response to stretch and probably reflects elastic recoil of the extracellular matrix surrounding the dendritic terminals. The rapid, partial repolarization depends on holding potential and is abolished by 4-aminopyridine (4-AP; 10 mM), implicating a fast-activating, fast-inactivating K+ conductance; TEA (60 mM) abolishes the remaining slow repolarization to the plateau. In intact cells, but not dendritic segments, regenerative depolarizations can arise in response to stretch or depolarizing current pulses; they are reduced by CdCl2 (10 microM) in the saline containing TEA and 4-AP and probably reflect current spread from Ca2+ influx at presynaptic terminals in the ganglion. We found no evidence for other voltage-activated conductances. Unlike morphologically similar "nonspiking" thoracic receptors of other species, E. analoga's nonspiking neurons are electrically compact and do not boost the analogue afferent signal by voltage-activated inward currents. The most prominent (only?) voltage-activated extra-ganglionic conductances are for potassium; by reducing the slope of the stretch-plateau depolarization curve, they extend each neuron's functional range to the full range of sensitivity of the receptor.

Sensitivity of the sand crab Emerita analoga to a weathered oil.

Sensitivity of the sand crab Emerita analoga to a weathered oil.

Distribution and Regulation of Esterases That Hydrolyze Methyl Farnesoate inHomarus americanusand Other Crustaceans

Ester hydrolysis of methyl farnesoate (MF) by crustacean tissue homogenates was measured using the substrate [3H]MF in a radiochemical partition assay. Tissues were obtained from the lobsterHomarus americanus,penaeid shrimpSicyonia ingentis,thalanassid shrimpCallianassa californiensis,sand crabEmerita analoga,and spider crabPugettia producta.The greatest specific activities were recovered from the hepatopancreas (239 to 11,500 pmol MF/min-mg total protein). Hepatopancreatic homogenates ofC. californiensiswere significantly more active than homogenates from the other species. In the lobster, esterases that hydrolyze MF were associated with lipid storage (R) cells of the hepatopancreas. Enzyme activity of lobster larval homogenates increased 1.5-fold during the second stage of development. The rate of MF hydrolysis by esterases extracted from the juvenile lobster hepatopancreas could not be correlated with molt stage or sex and was not significantly influenced by eyestalk ablation, mandibular organ ablation, or MF injection.

Replacement of an inherited stretch receptor by a newly evolved stretch receptor in hippid sand crabs

Primary sensory neurons that are motoneuron-like in morphology and often nonspiking (transmit afferent signals as graded depolarizations) characterize an unusual type of stretch receptor in decapod crustaceans. Nonspiking and spiking receptors occur in similar positions at homologous joints in different species and have been presumed to be homologous, the spiking one considered "primitive". To better understand the evolutionary origin of these stretch receptors and why some are nonspiking, we examined the spiking telson-uropod stretch receptors in the spiny sand crab Blepharipoda occidentalis (Albuneidae) and the squat lobster Munida quadrispina (Galatheidae) and compared them with the nonspking telson-uropod stretch receptor of the mole sand crab Emerita analoga (Hippidae). The position, morphology and responses to stretch of the sensory neurons, and the ultrastructure of the elastic strand portion of the receptor are similar in M. quadrispina and B. occidentalis, except that in B. occidentalis the receptor muscles are substantially smaller and the extracellular matrix of the elastic receptor strand is both more extensive and more organized, reminiscent of the ultrastructure of E. analoga's nonspiking receptor. We conclude that the spiking telson-uropod stretch receptors of albuneids and galatheids are homologous. The differences in the ultrastructure of their receptor strands imply that the efficiency of coupling receptor length change to deformation of the dendritic termini increases in the order M. quadrispina < B. occidentalis < E. analoga. The spiking and nonspiking telson-uropod stretch receptors differ anatomically in three major respects that appear to preclude their homology. (1) The receptor strands are on opposite sides of a conserved muscle. (2) The sensory somata are in different regions of the sixth abdominal ganglion: a lateral cluster of somata for the spiking sensory neurons and two medial clusters, one anterior, one posterior, for the nonspiking sensory neurons. (3) The neuropil projections of the sensory neurons are different. We conclude that the hippid's nonspiking telson-uropod stretch receptor evolved de novo and not by modification of the ancestral anomuran telson-uropod stretch receptor (which Hippidae have lost).

Geographic variation in the reproductive biology of the sand crab Emerita analoga (Stimpson) on the California coast

Reproductive characteristics were measured in 23 populations of the sand crab Emerita analoga Stimpson in midsummer over ≈ 1000 km of the California coast. Significant geographic patterns were found in the female size at maturity, the size and age distribution of ovigerous crabs, and an estimate of population fecundity. No geographic patterns were found in egg size and size-specific fecundity. Crabs from southern sites reproduced at smaller sizes and younger ages and attained smaller maximum sizes than crabs from northern sites. Young of the year crabs at northern sites matured at larger sizes, reproduced in smaller proportions, and produced larger initial clutches than southern crabs. Size at maturity and the size distribution of ovigerous crabs were inversely correlated with water temperature. Fecundity was significantly correlated with crab carapace length in all populations but no geographic trend was found in size-specific fecundity. The lack of overlap in the size ranges of ovigerous crabs did not allow direct comparisons of fecundity-size regressions between northern and southern populations. The relationships of fecundity and crab size varied significantly among populations in both the northern and the southern groups. Estimates of population fecundity decreased significantly from north to south. That trend was related to geographic patterns in the size and age distribution of ovigerous crabs.

Abnormal reproduction of the sand crab Emerita analoga in the vicinity of a nuclear generating station in Southern California

Female sand crabs (Emerita analoga) were sampled from 12 beaches along a 350 km stretch of Southern California coastline during the reproductive season in July, 1982. The percentage of mature females with egg masses and the condition of those egg masses were examined at each site. The proportion of mature females with egg masses varied only slightly between beaches. However, at sites within about 20 km of the San Onofre Nuclear Generating Station, a high percentage of females carried egg masses consisting of empty egg shells. A transplant experiment was conducted. Females with empty egg masses were taken from the 6.5 km N study site, where only 5% of the mature females carried normal egg masses, and transferred to running unfiltered seawater in Santa Barbara. After 2 wk, about a third of the transplanted females carried normal egg masses, while at the same time the proportion of mature females with normal egg masses remained at 5% on the beach of origin. Heated water discharged from the nuclear generating station is probably not the cause of the abnormal reproduction of sand crabs along the nearby coast. More likely causes are: (1) runoff of agricultural pesticides from a creek 3 km north of the nuclear generating plant; (2) release of metals from corroding cooling pipes, and/or (3) increased turbidity of the nearshore waters.

Homologies Between Body Movements and Muscular Contractions in the Locomotion of Two Decapods of Different Families

ABSTRACT The movements performed by the abdomen and tailfan during tailflipping in the sand crab Blepharipoda occidentalis (family Albuneidae) are described from an analysis of high-speed cinematic film (Figs. 1, 2, 3 A), and compared with component movements in the swimming-by-uropod-beating behaviour of the sand crab Emerita analoga (Family Hippidae) (Fig. 3 B; Paul, 1971). The most striking qualitative difference is the absence of uropod retraction and protraction in Blepharipoda. Comparisons of clectromyo-grams recorded from some of the principal muscles involved in these overtly very different behaviour patterns reveal that homologous muscles in the two sand crabs tend to be activated at comparable phase positions (Table 1). Tailflipping and uropod beating in the two crabs appear to be homologous, and to have been derived from ancestral macruran tailflipping.

Depth regulatory behavior of the first stage zoea larvae of the sand crab Emerita analoga Stimpson (Decapoda: Hippidae)

Laboratory studies of the behavior of first stage zoea larvae of the sand crab Emerita analoga Stimpson have shown that while newly-hatched larvae are strongly photopositive, this response lasts only about four hours, as the larvae rapidly become photonegative. After becoming photonegative, a large proportion of the larvae remain so throughout the first four days of life if they are fed Artemia nauplii; if starved, the larvae become significantly more photopositive than when fed. Both the photopositive response of newly-hatched larvae and the reversal to photopositive behavior in response to starvation are only apparent under horizontal test conditions. Increases in hydrostatic pressure stimulate swimming activity among the larvae; responsiveness to pressure being greatest at hatching and decreasing thereafter. The pressure response is strongly oriented to light; pressure-stimulated larvae will swim towards a light source regardless of whether this involves upward, downward, or horizontal motion. Experiments suggest that the pressure response provides the primary mechanism for depth regulation among young larvae; gravity and light may augment the pressure ‘sense’ by serving as primary orientational cues. The nutritional status of an individual larva may alter its depth-regulatory capabilities, but this effect is not yet clear.

Behavior and Physical Factors Causing Migration and Aggregation of the Sand Crab Emerita Analoga (Stimpson)

Migration and distribution of Emerita on sand beaches can be explained in terms of water flow and a simple behavioral response. Wash zones of sand beaches are bounded burrow out of fluid sand and so are kept within the boundaries of the wave wash. As the position of a wash zone is shifted with the tide, Emerita are carried in it to new locations on the beach. Lateral flow within the wave wash distributes Emerita into clumps along the shore.

SEASONAL VARIATION IN THE SAND CRAB EMERITA ANALOGA (DECAPODA, HIPPIDAE) IN THE SANTA BARBARA AREA OF CALIFORNIA

Studies were made of the population structure and life cycle of the sand crab Emerita analoga (Stimpson). Frequent sampling of the beach and of the plankton during a two‐year period indicates: 1) the population structure of the species differs from beach to beach; 2) an aggregation is not necessarily characteristic of the entire beach population; 3) seasonal changes drastically alter the population structure of sand crabs; and 4) occurrence and abundance of zoeae in the plankton closely parallel the arrival of megalopae on the beaches, but not necessarily on any one beach.The life cycle of this species can now be summarized as follows: The mating season in late spring and summer precedes a continual production and release of young during the summer. These pelagic zoeae pass through at least five molts before returning to shore as megalopae. Megalopae arrive in quantity on our beaches as early as September and continue to arrive during winter and spring. By mid‐November the reproductive females that prevailed in late summer apparently disappear. The majority of the beach population during winter and early spring consists of megalopae, juveniles, and males; this suggests an annual cycle for the species.The progressive seasonal increase in the percentage of females in the larger sizes, coupled with the relative absence of females in some of the smaller size classes, suggest a sex reversal (protandric hermaphroditism).