During 2014-2016, severe marine heatwaves in the northeast Pacific triggered well-documented disturbances including mass mortalities, harmful algal blooms, and declines in subtidal kelp beds. ...However, less attention has been directed towards understanding how changes in sea surface temperature (SST) and alongshore currents during this period influenced the geographic distribution of coastal taxa. Here, we examine these effects in northern California, USA, with a focus on the region between Point Reyes and Point Arena. This region represents an important biogeographic transition zone that lies <150 km north of Monterey Bay, California, where numerous southern species have historically reached their northern (poleward) range limits. We report substantial changes in geographic distributions and/or abundances across a diverse suite of 67 southern species, including an unprecedented number of poleward range extensions (37) and striking increases in the recruitment of owl limpets (Lottia gigantea) and volcano barnacles (Tetraclita rubescens). These ecological responses likely arose through the combined effects of extreme SST, periods of anomalous poleward flow, and the unusually long duration of heatwave events. Prolonged marine heatwaves and enhanced poleward dispersal may play an important role in longer-term shifts in the composition of coastal communities in northern California and other biogeographic transition zones.
A small bivalve mollusk previously only known from the Pleistocene of Los Angeles County has recently been found living intertidally near Santa Barbara, California. The bivalve has been determined to ...be
(Willett, 1937), a member of the Galeommatoidea J.E. Gray, 1840. We document the habitat for the newly discovered
, and compare it to
(Berry, 1963), the other extant member of this genus recorded from the region.
is rare, and while many galeommatoid species have been shown to be commensal with other invertebrates, we have been unable to determine any specific commensal relationships for it.
Felimare californiensis
(=
Hypselodoris californiensis
) was once common throughout the Southern California Bight (SCB) and California Channel Islands. This well-known shallow-water nudibranch, which ...specializes on dysideid sponges, has persisted for decades in Mexico, but in California disappeared from its entire range by 1984. Since reappearing in 2003, it has been found only at Santa Catalina Island, plus sightings of single individuals in 2011 at Santa Cruz Island and San Diego. The decline of
F. californiensis
in California was documented using published historical records, museum collections, unpublished field accounts, and images posted online. The loss of this emblematic species is unique among Californian nudibranchs, including (1) its congener
Felimare porterae
(=
Mexichromis porterae
), with which it appears to overlap in diet, and (2) opisthobranch species with similar historical geographic ranges and mode of development. The decline in
F. californiensis
is not predicted by warming trends and climate variation over the past 40 years, including the strong El Niño events of 1983 and 1998. Coastal pollution from the large human population in southern California may have impacted
Dysidea amblia
, the primary reported prey of
F. californiensis
. Historical overcollecting of the nudibranch and habitat loss through the development of major ports likely also contributed to its decline. Sightings since 2003 are consistent with a nascent recovery, as elements of water quality have improved in the SCB in recent decades.
The North Pacific nudibranch species
Triopha catalinae
(Cooper,
1863
), also known as the clown nudibranch, includes two distinct morphotypes: the trans-Pacific morphotype, known from South Korea to ...Southern California, and the eastern Pacific-only morphotype from Southeast Alaska to Baja California. We tested the hypothesis that
Triopha catalinae
is a species complex by applying an integrative taxonomic approach that included (1) phylogenetic analyses of the mitochondrial 16S and COI, and the nuclear Histone H3 genes; (2) haplotype network analysis based on COI sequences; (3) Automatic Barcode Gap Discovery (ABGD) species delimitation analysis based on 16S and COI sequences; and (4) comparative internal and external morphological studies. Specimens of two morphotypes were found to be genetically distinct; they clustered into two well-supported clades in the phylogenetic analyses and two groups in the TCS haplotype network. Moreover, these two groups displayed morphological differences in the dorsal tubercles and radula structure: the trans-Pacific morphotype specimens possess relatively small and dendritic dorsal tubercles, two rows of arborescent tubercles on the dorso-lateral appendages of larger individuals, and radular formula 19–24 × (9–12.5–10.1.5–10.9–12). Specimens of the eastern Pacific-only morphotype have relatively large, conical or rounded dorsal tubercles, and radular formula 48–79 × (16–18.17–33.1.17–33.16–18). Finally, the ABGD analysis confirmed that these two morphotypes constitute different species. A review of the literature (including original descriptions) and available type material revealed that
Triopha modesta
Bergh,
1880
and
T. catalinae
are the valid names for the trans-Pacific and eastern Pacific-only morphotype, respectively.
In 1977,
Phidiana hiltoni
(O’Donoghue in J. Entomol Zool (Pomona College, Claremont, California) 19:77–119,
1927
) began spreading northward from Monterey, California. By 1992, it had reached Duxbury ...Reef (37° 53′ 23″ N, 122° 41′ 59″ W), 100 km to the north, where other nudibranchs subsequently appeared to decline. The role of
P
.
hiltoni
in this decline was investigated through diet analysis, feeding trials, and comparison of historical and recent abundance data. In the wild,
P
.
hiltoni
preyed largely on hydroids, but also showed evidence of predation on nudibranchs. In the laboratory,
P
.
hiltoni
attacked most of the dendronotid and aeolid nudibranchs presented to it, ingesting small individuals whole. The pooled abundance of nudibranchs vulnerable to attack by
P
.
hiltoni
declined an average of two-thirds at Duxbury Reef since its arrival, compared to (1) no change in the non-vulnerable species and (2) no change in either group at two other sites where
P
.
hiltoni
was one to two orders of magnitude less abundant.
Phidiana
hiltoni
therefore appears to have caused this decline, likely through a combination of direct predation and competition for prey. A brief larval period, combined with cyclonic re-circulation in the lee of Point Reyes, may be driving self-recruitment of
P
.
hiltoni
at Duxbury Reef, as well as hindering further northward spread.
Abstract
Globally, a small number of plants have adapted to terrestrial outcroppings of serpentine geology, which are characterized by soils with low levels of essential mineral nutrients (N, P, K, ...Ca, Mo) and toxic levels of heavy metals (Ni, Cr, Co). Paradoxically, many of these plants are restricted to this harsh environment. Caulanthus ampexlicaulis var. barbarae (Brassicaceae) is a rare annual plant that is strictly endemic to a small set of isolated serpentine outcrops in the coastal mountains of central California. The goals of the work presented here were to 1) determine the patterns of genetic connectivity among all known populations of C. ampexlicaulis var. barbarae, and 2) estimate contemporary effective population sizes (Ne), to inform ongoing genomic analyses of the evolutionary history of this taxon, and to provide a foundation upon which to model its future evolutionary potential and long-term viability in a changing environment. Eleven populations of this taxon were sampled, and population-genetic parameters were estimated using 11 nuclear microsatellite markers. Contemporary effective population sizes were estimated using multiple methods and found to be strikingly small (typically Ne < 10). Further, our data showed that a substantial component of genetic connectivity of this taxon is not at equilibrium, and instead showed sporadic gene flow. Several lines of evidence indicate that gene flow between isolated populations is maintained through long-distance seed dispersal (e.g., >1 km), possibly via zoochory.
Morphological examination and molecular analyses of specimens of the genus
Limacia
collected in the Eastern Pacific Ocean indicate that four species of
Limacia
occur in the region.
Limacia cockerelli
..., previously considered to range from Alaska to Baja California, is common only in the northern part of its former range. An undescribed pseudocryptic species, previously included as
L. cockerelli
, occurs from Northern California to the Baja California Peninsula and is the most common species of
Limacia
in Southern California and Northern Mexico. Another new species similar to
L. cockerelli
is described from Antofagasta, Chile and constitutes the first record of the genus
Limacia
in the Southeastern Pacific Ocean. These two new species are formally described herein. Finally,
Limacia janssi
is a genetically and morphologically distinct tropical species ranging from Baja California to Panama. Species delimitation analyses based on molecular data and unique morphological traits from the dorsum, radula, and reproductive systems are useful in distinguishing these species
Molecular and morphological evidence support the view that the widely distributed species
Berthella stellata
(Risso, 1826) is a species complex of at least eight different species. The closely ...related species
Berthella plumula
(Montagu, 1803), examined for comparison, is also a complex of two species; the name
B. plumula
is retained for the Atlantic species and the name
Berthella perforata
(Philippi, 1844) is proposed for the Mediterranean species. The
B. stellata
species complex forms a monophyletic group when the Eastern Pacific species
Berthella strongi
(MacFarland, 1966) is included. Based on a critical review of the literature, the name
Berthella stellata
is retained for the Eastern Atlantic and Mediterranean species, and the name
Berthella pellucida
(Pease, 1860) is resurrected for a species found in the Hawaiian Islands. Two new species from the Caribbean region (
Berthella nebula
sp. nov.,
Berthella vialactea
sp. nov.) and one from the Eastern Pacific (
Berthella andromeda
sp. nov.) are described herein, but the status of the Brazilian species
B. tupala
Er. Marcus, 1957 remains uncertain. Two possible new species from the Eastern Pacific, represented by one specimen each, were recovered in the phylogenetic analyses but not formally described. It is hypothesized that additional species of this complex may occur in other parts of the Indo-Pacific tropics, particularly in the Indian Ocean.
(W. H. Dall, 1900) is a widespread species of heterobranch sea slug distributed across the North Pacific Ocean, from Korea and Japan to the Galapagos Islands. Two distinct morphotypes are observed in
..., which differ in external coloration, egg-mass morphology and geographic distribution (with the exception of a small range overlap in Southern California). Molecular and morphological data obtained in this study reveals that these two morphotypes constitute distinct species. The name
(type locality: San Pedro, California) is retained for the southern morphotype, whereas the name
(J. Q. Burch, 1944) (type locality: Crescent City, California) is resurrected for the northern morphotype. Moreover, molecular phylogenetic analyses recovered
as sister to
, in a well-supported clade separate from
, suggesting that the classification of
may need additional revision.
Molecular analyses of samples of Doriopsilla albopunctata and its ‘twin’ species Doriopsilla gemela collected from their entire geographic ranges in the north‐eastern Pacific revealed an unexpected ...level of species diversity. Species delimitation analyses recovered five distinct species in the complex. When the specimens were re‐examined morphologically in the light of the molecular results, some external and internal differences between them became evident; thus, these species are considered pseudocryptic. The ranges of the three species previously named D. albopunctata overlap partially or entirely, and this along with anecdotal evidence of prezygotic isolation suggests sympatric speciation may be at play. On the contrary, the ranges of the two species previously named D. gemela do not overlap and their developmental modes differ. A review of the literature was conducted to clarify the taxonomy of the species complex, and we concluded that two available names (D. fulva and D. gemela) can be confidently assigned to two of the species. The original description of D. albopunctata is ambiguous, but the common usage of the name is fixed herein with the designation of a neotype for the most common intertidal southern California species. Finally, two new names are introduced for the remaining two species.
PDF
