共查询到20条相似文献,搜索用时 232 毫秒
1.
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. 相似文献
2.
T. Knowles M. J. Leng M. Williams P. D. Taylor H. J. Sloane B. Okamura 《Marine Biology》2010,157(6):1171-1180
This is the first investigation of how two independent proxies for seawater temperature inference (zooid size variation and
oxygen isotope ratios of skeletal carbonate) relate to the actual measured ranges of temperature experienced by cheilostome
bryozoan colonies. Nine specimens of the bimineralic marine cheilostome bryozoan Pentapora foliacea (Ellis and Solander, 1786) were analysed, collected from ~18-m depth at two localities in Wales, UK—four from Skomer Island
(51°42′510″N, 5°13′42.60″W) and five from Porth Ysgaden, Lleyn Peninsula (52°54′6.75″N, 4°38′47.34″W). The annual range of
temperature implied by zooid size variability provides a good approximation of the actual range of temperature recorded by
a datalogger. However, annual ranges of temperature reconstructed from skeletal oxygen isotope ratios were narrower, typically
not showing the lowest temperatures experienced by the colonies. This can be explained by progressive thickening of zooid
skeletal walls during the life of the colony that homogenises the temperature signal by time-averaging over the lifetime of
the colonies. Our study provides evidence that a combined morphological isotope approach has great potential in the reconstruction
of annual ranges in seawater temperatures from historical and fossil bryozoans, particularly for species that lack ontogenetic
skeletal wall thickening and bimineralic skeletal composition. As cheilostome bryozoans have been common in benthic communities
since the Late Cretaceous, they represent a valuable and underutilised resource for the interpretation of environmental regimes. 相似文献
3.
Adults of motile intertidal invertebrates are able to seek shelter to avoid environmental stress associated with low tides,
but embryos within egg masses are effectively sessile for the duration of their encapsulation. Gastropod egg masses from 34
taxa on two rocky shores in SE Australia (34°37′08″S, 150°92′03″E and 34°35′45″S, 150°53′20″E) were surveyed over 2 years
(June 2002–May 2004) to test the hypothesis that eggs are deposited in patterns that minimize exposure to environmental stress.
Egg masses were expected to be predominantly deposited in shaded habitats not prone to environmental extremes. It was also
anticipated that the deposition of egg masses in habitats exposed to UVR, desiccation, and/or extremes in temperature would
occur when exposure to these abiotic factors was minimized. Among the taxa investigated, only four species spawned in full
sun (Bembicium nanum, Nerita morio, Siphonaria zelandica and S. denticulata). Summer had the highest UVR index, water temperature, and air temperature as well as the lowest daytime tides. Univariate
and multivariate analyses confirmed that egg mass abundance was highest during summer, with no change in egg mass size. This
study shows that those species depositing egg masses on the surfaces of rock platforms do not adjust the seasonal timing or
macrohabitat location of their spawning to avoid physiologically stressful conditions, particularly UVR. Alternate reasons
for the evolution of egg mass deposition behavior in apparently sub-optimal habitats are discussed, and it is almost certainly
the complex interplay of a variety of highly species-specific factors that is responsible for the patterns observed. 相似文献
4.
The recovery of Ascophyllum nodosum, and the associated benthic community, was followed after repeated trampling disturbance at different intensities, from 2005
to 2010, at its southern limit (41°41′27″N; 8°50′57″W). The cover of A. nodosum and associated organisms and the demography of A. nodosum individuals in the most disturbed areas were followed over a recovery period of 54 months. Recovery of A. nodosum assemblages was negatively affected by increasing trampling intensity. After 54 months, the highest intensity plots were
still significantly different from control plots. Growth and mortality rates of A. nodosum increased shortly after disturbance but progressively recovered to levels close to control plots. The results of this study
demonstrate the sensitivity of this habitat-building species to human trampling and also show its plasticity to cope with
disturbance events. 相似文献
5.
The temperate sea anemone Anthopleura elegantissima is facultatively symbiotic with unicellular algae. Symbiotic A. elegantissima can supplement heterotrophic feeding with excess photosynthate from their algal partners, while asymbiotic individuals must
rely solely on heterotrophy. A. elegantissima individuals were collected from Swirl Rocks, Washington (48°25′6″ N, 122°50′58″ W) in July 2010, and prey capture and feeding
characteristics were measured to determine whether asymbiotic individuals are more efficient predators. Feeding abilities
were then measured again after a 3-week exposure to full sunlight or shaded conditions. Freshly collected asymbiotic anemones
had larger nematocysts, but symbiotic individuals showed greater nematocyte sensitivity. Sunlight enhanced digestion and reduced
cnida density in all anemones regardless of symbiotic state. Results suggest that the phototropic potential of A. elegantissima, as influenced by symbiotic condition, has little effect on heterotrophic capacity. The anemones appear to maximize heterotrophic
energy input independent of the presence or identity of their algal symbionts. 相似文献
6.
Field experiments were conducted from dusk to dawn off St. John (18° 18′ 59.32″ N, 64° 43′ 24.5″ W) and Guana Island (18°
28″ 28.31″ N, 64° 34′ 30.83″ W), Virgin Islands from June through August 2008-2010 to assess the sensory cues used by the
nocturnal/crepuscular fish-parasitic gnathiid isopod, Gnathia marleyi, to locate fish hosts. Experimental traps providing both visual and olfactory cues from live French grunts (Haemulon flavioliniatum) attracted significantly more gnathiids than traps providing only visual cues or control traps (empty or with a rock), which
were not significantly different from each other. In another experiment, traps providing both cues and only olfactory cues
attracted significantly more gnathiids than empty control traps, but were not significantly different from each other. Our
findings suggest that during nocturnal and crepuscular periods, visual cues provided by resting or slow-moving fish are not
alone sufficient to attract gnathiids, while olfactory cues alone are. The traps designed for this study offer a new method
of sampling free-living gnathiid isopods. 相似文献
7.
Mitochondrial cytochrome oxidase subunit one (COI) sequence, nuclear microsatellites, and amplified fragment length polymorphisms
(AFLPs) were used to evaluate connectivity among nine red abalone (Haliotis rufescens) populations sampled between August 1998 and November 2003 along approximately 1,300 km of California coastline from Crescent
City (41°46′N, 124°12′W) to San Miguel Island (34°02′N, 120°22′W). COI sequences and microsatellite genotypes did not show
significant genetic divergence among nine sampled populations. A subset of five populations spanning the geographic range
of the study was scored for 163 polymorphic AFLP markers. Of these, 41 loci showed significant divergence (P < 0.001) among populations. Still, no AFLP markers were diagnostic for any of the study populations, and assignment tests
did not consistently assign individuals to the correct population. Although the AFLP data are the first to suggest there is
significant genetic differentiation among California red abalone populations, the discordance between the different genetic
markers needs further study before unambiguous conclusions can be drawn with respect to connectivity among the populations.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
8.
9.
Giuseppe Guarnieri Antonio Terlizzi Stanislao Bevilacqua Simonetta Fraschetti 《Marine Biology》2012,159(5):1155-1164
Submarine caves are considered as a top priority for conservation, but the effects of common pressures are poorly known for
these habitats. Here, we examined the effect of recreational human visitation on a selection of submarine caves in a Mediterranean
Marine Protected Area (40°35′40″N; 8°11′39″E) where diving activities are regulated. Sampling was conducted in visited and
not visited caves to assess whether diving activities have a significant effect on cave habitats, what are the components
of biodiversity most affected by this disturbance, and its potential effects on spatial heterogeneity of benthic assemblages.
Results clearly showed that human visitation could significantly affect spatial patterns of benthic assemblages. Organisms
with erect growth forms were significantly more abundant and homogeneously distributed where diving activities are forbidden.
An increase in the small-scale heterogeneity of assemblages and a decrease in their three-dimensional structure could be the
ultimate consequences of human visitation. The interaction between specific stressors and the patterns of distribution of
species and assemblages can drive their spatial heterogeneity also in unique habitats like marine caves, representing an early
warning for the development of appropriate management measures. 相似文献
10.
The ascidian Styela clava, native to the north-west Pacific, is an invasive species affecting New Zealand’s marine ecosystems, biodiversity and aquaculture
operations. To provide detailed information on the reproductive biology of S. clava in New Zealand for post-border biosecurity management, long-term seasonal patterns of gametogenesis were determined from
May 2006 to May 2008 in Auckland’s Waitemata Harbour (36°49′20″S, 174°45′85″E). Of particular interest was whether the critical
15°C threshold spawning temperature for reproduction observed in the Northern Hemisphere applied here to the first Southern
Hemisphere study. S. clava gametogenesis followed a regular seasonal cycle with ripe gametes appearing as early as September and persisting to June;
this time frame corresponds to the period when sea surface temperatures in the region first reach 15°C and with spawning occurring
mainly during late summer to early autumn. From photoperiod manipulation, it was determined that spawning occurred at approximately
18:20. The extended reproductive period and a short generation time in the Waitemata Harbour provides a lengthy opportunity
for S. clava to spread. Findings are discussed in relation to S. clava’s post-border management. 相似文献
11.
Dana M. Bethea Loraine Hale John K. Carlson Enric Cortés Charles A. Manire James Gelsleichter 《Marine Biology》2007,152(5):1009-1020
To examine variation in diet and daily ration of the bonnethead shark, Sphyrna tiburo (Linnaeus 1758), animals were collected from three areas in the eastern Gulf of Mexico: northwest Florida (∼29°40′N, 85°13′W),
Tampa Bay near Anclote Key (∼28°10′N, 82°42.5′W), and Florida Bay (∼24°50′N, 80°48′W) from March through September, 1998–2000.
In each area, diet was assessed by life stage (young-of-the year, juveniles, and adults) and quantified using five indices:
percent by number (%N), percent by weight (%W), frequency of occurrence (%O), index of relative importance expressed on a
percent basis (%IRI), and %IRI based on diet category (%IRIDC). Diet could not be assessed for young-of-the-year in Tampa Bay or Florida Bay owing to low sample size. Diet analysis showed
an ontogenetic shift in northwest Florida. Young-of-the-year stomachs from northwest Florida (n = 68, 1 empty) contained a mix of seagrass and crustaceans while juvenile stomachs (n = 82, 0 empty) contained a mix of crabs and seagrass and adult stomachs (n = 39, 1 empty) contained almost exclusively crabs. Crabs made up the majority of both juvenile and adult diet in Tampa Bay
(n = 79, 2 empty, and n = 88, 1 empty, respectively). Juvenile stomachs from Florida Bay (n = 72, 0 empty) contained seagrass and a mix of crustaceans while adult stomachs contained more shrimp and cephalopods (n = 82, 3 empty). Diets in northwest Florida and Tampa Bay were similar. The diet in Florida Bay was different from those in
the other two areas, consisting of fewer crabs and more cephalopods and lobsters. Plant material was found in large quantities
in all stomachs examined from all locations (>15 %IRIDC in 6 of the 7 life stage-area combinations, >30 %IRIDC in 4 of the 7 combinations, and 62 %IRIDC in young-of-the-year diet in northwest Florida). Using species- and area-specific inputs, a bioenergetic model was constructed
to estimate daily ration. Models were constructed under two scenarios: assuming plant material was and was not part of the
diet. Overall, daily ration was significantly different by sex, life stage, and region. The bioenergetic model predicted increasing
daily ration with decreasing latitude and decreasing daily ration with ontogeny regardless of the inclusion or exclusion of
plant material. These results provide evidence that bonnetheads continuously exposed to warmer temperatures have elevated
metabolism and require additional energy consumption to maintain growth and reproduction.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
12.
Presence of Alexandrium catenella and paralytic shellfish toxins in finfish, shellfish and rock crabs in Monterey Bay, California, USA 总被引:1,自引:0,他引:1
The central California coast is a highly productive, biodiverse region that is frequently affected by the toxin-producing
dinoflagellate Alexandrium catenella. Despite the consistent presence of A. catenella along our coast, very little is known about the movement of its toxins through local marine food webs. In the present study,
we investigated 13 species of commercial finfish and rock crabs harvested in Monterey Bay, California for the presence of
paralytic shellfish toxins (PSTs) and compared them to the presence of A. catenella and PSTs in sentinel shellfish over a 3-year period. Between 2003 and 2005, A. catenella was noted in 55% of surface water samples (n = 307) and reached a maximum concentration of 17,387 cells L−1 at our nearshore site in Monterey Bay. Peak cell densities occurred in the month of July and were associated with elevated
shellfish toxicity in the summers of 2004 and 2005. When A. catenella was present, particulate PSTs were detected 71% of the time and reached a maximum concentration of 962 ng STXeq L−1. Of the 13 species tested, we frequently detected PSTs in Pacific sardines (Sardinops sagax; maximum 250 μg STXeq 100 g−1), northern anchovies (Engraulis mordax; maximum 23.2 μg STXeq 100 g−1), brown rock crabs (Cancer antennarius; maximum 49.3 μg STXeq 100 g−1) and red rock crabs (C. productus; 23.8 μg STXeq 100 g−1). PSTs were also present in one sample of Pacific herring (Clupea pallas; 13.3 μg STXeq 100 g−1) and one sample of English sole (Pleuronectes vetulus; 4.5 μg STXeq 100 g−1), and not detected in seven other species of flatfish tested. The presence of PSTs in several of these organisms reveals
that toxins produced by A. catenella are more prevalent in California food webs than previously thought and also indicates potential routes of toxin transfer
to higher trophic levels.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
13.
14.
Andrea Gori Sergio Rossi Cristina Linares Elisa Berganzo Covadonga Orejas Mark RT Dale Josep-Maria Gili 《Marine Biology》2011,158(8):1721-1732
In the Western Mediterranean Sea, the gorgonian Eunicella singularis (Esper, 1794) is found at high densities on sublittoral bottoms at depths from 10 to 70 m. Shallow colonies have symbiotic
zooxanthellae that deeper colonies lack. While knowledge of the ecology of the shallow populations has increased during the
last decades, there is almost no information on the ecology of the deep sublittoral populations. In October and November 2004
at Cap de Creus (42°19′12″ N; 03°19′34″ E), an analysis of video transects made by a remotely operated vehicle showed that
shallow populations (10–25 m depth) were dominated by small, non-reproductive colonies, while deep sublittoral populations
(50–67 m depth) were dominated by medium-sized colonies. Average and maximum colony heights were greater in the deeper populations,
with these deeper populations also forming larger patch sizes and more extensive regions of continuous substrate coverage.
These results suggest that shallow habitats are suitable for E. singularis, as shown by the high recruitment rate, but perturbations may limit or delay the development of these populations into a
mature stage. This contrasts with the deep sublittoral habitats where higher environmental stability may allow the development
of mature populations dominated by larger, sexually mature colonies. 相似文献
15.
Pat M. Fidopiastis Daniel J. Bezdek Michael H. Horn Judith S. Kandel 《Marine Biology》2006,148(3):631-642
The zebraperch, Hermosilla azurea Jenkins and Evermann, a warm-temperate marine fish species with a strictly macroalgal diet, has a relatively long digestive
tract with an enlarged hindgut and an associated blind caecum (HC). In zebraperch sampled off Santa Catalina Island, California
(33°19′42′′N; 118°18′37′′W) in years 1995 through 2001, direct cell counts, gut epithelium assessment of bacterial attachment,
and short-chain fatty acid (SCFA) analyses verified that the zebraperch HC possesses a dense and morphologically diverse,
fermentative microbiota. Bacterial cell counts and morphological diversity were significantly higher in HC contents compared
to anterior gut regions, suggesting that microbial populations were growing along the digestive tract. Similarly, electron
micrographs of the HC epithelium revealed attached microbes, further supporting the possibility that these organisms constitute
resident microbiota. Five different SCFAs were detected in all three regions of the digestive tract, but levels were up to
three times greater in HC contents. Acetate was consistently the prevailing SCFA in all gut regions. Sequence analysis of
bacterial 16S rDNA was used to identify predominant bacterial groups in HC contents. Of the seven main bacterial types identified,
Enterovibrio spp. were the dominant bacteria in HC contents followed by species of Bacteroides,Faecalibacterium, and Desulfovibrio. Taken together, our findings show that the zebraperch HC harbors a consortium of microbes that appears to assist in the
breakdown of algal polysaccharides in the herbivorous diet of the fish. 相似文献
16.
Heather Elizabeth Braid Jonathan Deeds Stacey Lea DeGrasse John James Wilson Josephine Osborne Robert Harland Hanner 《Marine Biology》2012,159(1):25-31
In fall of 2009, several mass strandings of Humboldt squid (Dosidicus gigas) occurred on Vancouver Island (49°7′60N 125°54′0W). Morphological dissections coupled with DNA barcoding of stomach contents
revealed Sardinops sagax (Pacific sardine) and Clupea pallasii (Pacific herring) as their primary prey. Plastic nurdles, fishing line, bull kelp, eelgrass, and a guillemot feather were
also discovered. The primary prey, Pacific sardines and Pacific herring, are known to bioaccumulate paralytic shellfish toxins
(PSTs); additionally, both PSTs and domoic acid (DA) have been implicated in other mass strandings. Therefore, stomach contents,
and other tissues when possible, were tested for PSTs and DA. Testing revealed DA concentrations below regulatory guidance
levels for human consumption, yet PSTs were well in excess. Though we cannot conclude that PSTs were the definitive cause
of the strandings, our findings are the first report of PSTs in D. gigas. 相似文献
17.
The chaotic physical and chemical environment at deep-sea hydrothermal vents has been associated with an ecosystem with few
predators, arguably allowing the habitat to provide refuge for vulnerable species. The dominance of endemic limpets with thin,
open-coiled shells at north Pacific vents may support this view. To test their vulnerability to predation, the incidence of
healed repair scars, which are argued to reflect non-lethal encounters with predators, were examined on the shells of over
5,800 vent limpets of Lepetodrilus fucensis McLean (1988) that were collected from 13 to 18 August 1996. Three vent fields on the Juan de Fuca Ridge at ca. 2,200 m depth were sampled,
two within 70 m of 47°56.87′N 129°05.91′W, and one at 47°57.85′N 129°05.15′W with the conspicuous potential limpet predators,
the zoarcid fish Pachycara gymninium Anderson and Peden (1988), the galatheid crab Munidopsis alvisca Williams (1988), and the buccinid snail Buccinum thermophilum Harasewych and Kantor (2002). Limpets from the predator-rich vent were most often scarred, a significant difference created by the high incidence of
scars on small (<4 mm long) limpets in this sample. Collected with the limpets were small (median shell diameter 4.4 mm) buccinids.
They, rather than the larger, more conspicuous mobile fishes and crabs are argued to be the shell-damaging predator.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
18.
Marine communities are experiencing unprecedented rates of species homogenization due to the increasing success of invasive
species, but little is known about the mechanisms that allow a species to invade and persist in a new habitat. In central
California, native (Mytilus trossulus Gould 1850) and invasive (Mytilus galloprovincialis Lamarck 1819) blue mussels and their hybrids co-exist, providing an opportunity to analyze the mechanisms that determine
the distributions of these taxa. Spatial and temporal variation in temperature and salinity and the relative frequencies of
these mussel taxa were examined between 2000 and 2004 at four sites in San Francisco Bay and four in Monterey Bay, which were
chosen for their different positions along inferred estuarine/oceanic gradients in the hybrid zone. Mussels were genetically
identified as the parent species or hybrids by amplifying regions of two species-specific loci: the adhesive byssal thread
protein (Glu-5′) and the internal transcribed spacer region of ribosomal DNA (ITS 1). The proportion of M. trossulus at the eight hybrid zone sites correlated negatively with average salinity (R
2=0.60) and positively with maximal temperature (R
2≥0.72), a somewhat unexpected result given what is known about the phylogeography of this species. The proportion of M. galloprovincialis showed the opposite pattern. The proportion of hybrids was correlated neither with habitat temperature nor salinity. Genotypes
of mussel populations at an additional 13 sites from Coos Bay, Oregon (latitude 43.35°N) to Long Beach, California (latitude
33.72°N), sampled at various intervals between 2000 and 2004, were also determined. This survey confirmed previous reports
that the hybrid zone lies between Monterey and the Cape Mendocino region (latitudes 36.63°N–40.5°N). Within Monterey and San
Francisco Bays, however, the temporal comparisons (1990s vs. 2000s) revealed abrupt changes in the proportions of the two
parent species and their hybrids on annual and decadal time scales. These changes indicate that the blue mussel populations
are in a highly dynamic state. The survey also showed that, regardless of habitat, M. trossulus is consistently of smaller average size than either M. galloprovincialis or hybrids.
相似文献
Caren E. BrabyEmail: |
19.
Holly F. Swift William M. Hamner Bruce H. Robison Laurence P. Madin 《Marine Biology》2009,156(5):1049-1056
Behavioral observations using a remotely operated vehicle (ROV) in the Gulf of California in March, 2003, provided insights
into the vertical distribution, feeding and anatomy of the rare and delicate ctenophore Thalassocalyce inconstans. Additional archived ROV video records from the Monterey Bay Aquarium Research Institute of 288 sightings of T. inconstans and 2,437 individual observations of euphausiids in the Gulf of California and Monterey Canyon between 1989 and 2005 were
examined to determine ctenophore and euphausiid prey depth distributions with respect to temperature and dissolved oxygen
concentration [dO]. In the Gulf of California most ctenophores (96.9%) were above 350 m, the top of the oxygen minimum layer.
In Monterey Canyon the ctenophores were more widely distributed throughout the water column, including the hypoxic zone, to
depths as great as 3,500 m. Computer-aided behavioral analysis of two video records of the capture of euphausiids by T. inconstans showed that the ctenophore contracted its bell almost instantly (0.5 s), transforming its flattened, hemispherical resting
shape into a closed bi-lobed globe in which seawater and prey were engulfed. Euphausiids entrapped within the globe displayed
a previously undescribed escape response for krill (‘probing behavior’), in which they hovered and gently probed the inner
surfaces of the globe with antennae without stimulating further contraction by the ctenophore. Such rapid bell contraction
could be effected only by a peripheral sphincter muscle even though the presence of circumferential ring musculature was unknown
for the Phylum Ctenophora. Thereafter, several live T. inconstans were collected by hand off Barbados and microscopic observations confirmed that assumption. 相似文献