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1.
Although the spread of non-native algae is rapidly escalating, relatively few ecological studies have been done to gauge the impacts incurred to native flora and fauna. A reduction in the dominance of a native habitat-forming macroalga due to the replacement by an introduced species can have adverse effects on the community. The non-native red alga Grateloupia turuturu, first reported in Rhode Island, USA in 1994, has since extended its southern range into eastern Long Island Sound. This large alga has the potential to impact coastal communities by altering the floristic composition important to associated flora and fauna. A comparison of algal and epifaunal assemblages was made during 2006 and 2007 between native and non-native algal communities dominated by either G. turuturu or the native, Chondrus crispus at two sites in Long Island Sound. We found that within Grateloupia-dominated habitat, there was a large decrease in overall macrophyte biomass as compared to native habitat. We also found that habitat dominated by the non-native alga reduced species richness and total abundance of invertebrates relative to nearby habitats dominated by C. crispus. In addition, we found that the dominant mesofaunal species, important to higher trophic level consumers, had greatly reduced densities in communities dominated by the non-native alga.  相似文献   

2.
To assess the role that vision plays in the ability of the North Atlantic right whale (Eubalaena glacialis) to detect its primary prey species, the calanoid copepod Calanus finmarchicus, we have compared the absorbance spectrum of the E. glacialis rod visual pigment, the transmittance spectra of C. finmarchicus carotenoid pigments, as well as the downwelling irradiance and horizontal radiance spectra collected during springtime at three locations in the western Gulf of Maine. The E. glacialis rod visual pigment absorbs light maximally at 493 nm, while microspectrophotometric measurements of the C. finmarchicus carotenoid pigments reveal transmission spectra with minima matching very well with the E. glacialis rod visual pigment absorbance spectra maximum. Springtime spectral downwelling irradiance and horizontal radiance values from the surface waters of Cape Cod Bay and at all depths in Great South Channel overlap the E. glacialis rod absorbance spectrum, allowing C. finmarchicus to appear as a high‐contrast dark silhouette against a bright background spacelight, thus facilitating visually guided contrast foraging. In contrast, spectral downwelling irradiance and horizontal radiance at depth in Cape Cod Bay, and all depths in Wilkinson Basin, do not overlap the E. glacialis rod absorbance spectrum, providing little if any useful light for contrast vision.  相似文献   

3.
We describe a possible cryptic invasion of the toxic Western Pacific hydromedusa Gonionemus vertens (Cnidaria, Hydrozoa, Limnomedusae) in the Northwest Atlantic Ocean. G. vertens was first noticed in Eel Pond in Woods Hole (Cape Cod), Massachusetts in 1894, but nearly disappeared in the 1930s, coincident with a large scale die-off of its preferred eelgrass habitat. During the 1894–1930 period, G. vertens was the object of numerous studies by local scientists, and was not reported as stinging. In contrast, Western Pacific G. vertens are known for their toxic sting symptoms, which include severe pain, respiratory distress, and paralysis. Here, we report new sightings in the northwest Atlantic from the late twentieth century onwards. Sightings are most frequent in Waquoit Bay on the southern-facing shore of Cape Cod, Massachusetts, and on the island of Martha’s Vineyard, Massachusetts, but medusae have also been found in locations ranging from Long Island (New York) to Wellfleet Harbor on the north side of Cape Cod. We also describe reports of stings with symptoms similar to those produced by the toxic Western Pacific strain. The first sting report that we are aware of occurred in 1990 in Waquoit Bay, and stings have since occurred in most of G. vertens’ known Northwest Atlantic locations. It appears likely that the recent sightings associated with toxic stings represent a new, cryptic invasion of the Western Pacific form. These new observations are cause for public health concern, particularly as warmer temperatures associated with climate change may promote G. vertens blooms and thus the likelihood of dangerous human-jellyfish interactions in a populated, tourism-dependent region.  相似文献   

4.
The seasonal distribution and abundance of harbor seals occurring south of Maine were documented by counting the number of seals at traditional haulout locations. The average number of seals counted during each survey in Massachusetts and New Hampshire was 3,560 ± 255 (95% CI), 1983–1987. The maximum number of seals counted on any individual survey was 4,736 individuals. Fifty percent of all the surveys since January 1985 have resulted in counts greater than 4,000 seals reflecting a 27% increase in the abundance of seals in our study area since that date. Seventy-five percent of the seals in southern New England are located at haulout sites on Cape Cod and Nantucket Island. The largest aggregation of seals in the eastern United States occurs mid-winter at Monomoy Island and adjacent shoals. A single high count of 1,672 seals occurred at this site during the study period. An additional 271–374 seals were also counted in Rhode Island, Connecticut and eastern Long Island Sound during surveys conducted in March 1986 and 1987. The American sandlance Ammodytes americanus was the single dominant prey item of harbor seals in waters adjacent to Cape Cod based on the modified frequency of occurrence of each prey species in scat samples collected from three haulout sites on Cape Cod between 1984–1987. During January and February sandlance was the near exclusive prey item at Monomoy (99%, n= 80). During March and April, the frequency of Atlantic herring Clupea harengus increased in the scat samples at this site. Regional differences in the diet of seals reflect distinct prey communities throughout the study area. Since 1986, the percent occurrence and importance of sandlance in the diet of seals has decreased, reflecting an overall decrease in abundance of this prey species in waters adjacent to Cape Cod. In spite of fluctuations in abundance, and regional differences in the diet of seals throughout the study area, sandlance still comprised a minimum 55% of the total prey species of harbor seals throughout the study area.  相似文献   

5.
Gall wasps (Hymenoptera: Cynipidae) are phytophagous insects that often go unnoticed; however, when they are introduced to a new area or released from their natural enemies, they have the capacity to outbreak and cause extensive foliar damage. One such outbreaking pest, Zapatella davisae (Cynipidae: Cynipini), causes significant damage and mortality to black oak, Quercus velutina, in the northeastern United States. In this study, we aimed to identify the parasitoid community associated with Z. davisae, compare differences in percent parasitism of Z. davisae in Cape Cod and Long Island, and determine which parasitoid species contribute most to parasitism in each region. From both locations, we reared parasitoids, identified morphological groups, analyzed percent parasitism rates for each group, and used DNA barcoding to provide species‐level identifications. On Long Island, there was nearly 100% parasitism in 2015 followed by a near total collapse of the population in 2016. In contrast, parasitism rates were lower and remained consistent on Cape Cod between 2015 and 2016, which may explain the greater canopy damage observed in that region. Species of Sycophila were the dominant parasitoids, with one species Sycophila nr. novascotiae representing ~65% of reared parasitoids from Long Island, and two species of Sycophila (S. nr. novascotiae and S. foliatae) with near equal representations on Cape Cod. In order to manage an insect pest, it is important to understand factors that influence its mortality and survival. An understanding of how these infestations progress overtime can help predict the impact that newer infestations in Nantucket, MA, and coastal Rhode Island will have on black oak populations and will aid in the management of this rapidly spreading gall wasp pest.  相似文献   

6.
7.
Grateloupia turuturu Yamada is the currently accepted name for the invasive red alga that is present on coasts of the North Atlantic. Previously considered as G. doryphora (Montagne) M.A. Howe, populations of this invasive species were examined and their taxonomic position revised using molecular and morphological techniques. It was also thought that similar invasive populations in the Mediterranean should be identified as G. turuturu. This investigation used rbcL based molecular analyses to clarify the taxonomic position of Grateloupia “doryphora’ from the Straits of Messina. Our results indicate that this population is neither G. doryphora nor G. turuturu. It was placed separately in all analyses and grouped consistently with other Grateloupia species from the Pacific. On the basis of molecular data from this and previous investigations, it is evident that the status of the foliose Atlantic and Mediterranean entities is still unclear and a re-evaluation of the old names connected to them should be undertaken.  相似文献   

8.
The New England cottontail (Sylvilagus transitionalis) has suffered from extensive loss and fragmentation of its habitat and is now a species of conservation priority in the northeastern United States. Remnant New England cottontail populations currently occur in five geographically disjunct locations: southern Maine and southeastern New Hampshire (MENH); the Merrimack Valley in central New Hampshire (NH-MV); Cape Cod, Massachusetts (CC); parts of eastern Connecticut and Rhode Island (CTRI); and western Connecticut, southeastern New York and southwestern Massachusetts (CTNY). We used microsatellite genotyping to discern patterns of population structure, genetic variability, and demographic history across the species’ range and to assess whether the observed patterns are a consequence of recent habitat loss and fragmentation. Our findings show that the geographic populations are highly differentiated (overall F ST = 0.145; P < 0.001). Using Bayesian clustering analyses, we identified five genetic clusters, which corresponded closely to the geographic populations, but grouped MENH & NH-MV together (ME/NH) and identified an isolated population in eastern Connecticut (Bluff Point). The genetic clusters showed little evidence of recent gene flow and are highly influenced by genetic drift. The CC and Bluff Point populations show signs they experienced a genetic bottleneck, whereas the ME/NH population shows evidence of ongoing decline. Populations in Bluff Point, CC, and ME/NH also show significantly reduced genetic variation relative to the other clusters (CTNY and CTRI without Bluff Point). Without immediate human intervention, the short-term persistence of New England cottontail populations in Maine, New Hampshire and Cape Cod is at great risk. Conservation efforts at this time should focus on within-population sustainability and eventually restoring connectivity among these isolated populations.  相似文献   

9.
Nathan W. Riser 《Hydrobiologia》1993,266(1-3):141-157
A majority of the nemertine species from the western North Atlantic were originally described from life in the nineteenth century. Many of these were established by A. E. Verrill who had ‘an eye for species’ no matter which phylum he was working with, and thus when living nemertines which he described are encountered, they can usually be recognized. The morphology of most of these species has never been reported; some may prove to be species described earlier from the eastern North Atlantic. Morphological observations on the nemertine species from the North East coast of the Pacific are inadequate and have prevented satisfactory comparison with species from Japan and eastern Russia. The morphology of some species collected in the Gulf of Maine and from Cape Cod, as well as a re-examination of some of the slides of type specimens of species from the west coast of North America, indicates that their generic placement must be re-examined. The architectonic plan of the heteronemertines postulated over 100 years ago can not be substantiated and is redescribed. Three new heteronemertean genera are described: Tenuilineus gen.n. Parvicirrus gen.n., Tarrhomyos gen.n.  相似文献   

10.
Here, we report for the first time the presence of Dictyota cyanoloma in southern California. Dictyota cyanoloma is conspicuous in harbors and bays by its distinctive bright blue‐iridescent margins. This species was originally described from Europe, but subsequent studies have revealed that it represented an introduction from Australia. The current distribution of D. cyanoloma comprises southern Australia and the North East Atlantic, including the Mediterranean Sea and the Macaronesian islands. The presence of D. cyanoloma in southern California is supported by molecular cox1 and psbA gene sequences. A reconstruction of the invasive history based on nine polymorphic microsatellite markers reveals a close affinity of the Californian specimens with European populations. Dictyota cyanoloma in the United States appears to be (so far) restricted to the Californian coast from San Diego Bay in the south to Santa Catalina Island and Long Beach Harbor in the north. A correlative species distribution model suggests gradually declining habitat suitability north of the Southern Californian Bight and high suitability in Baja California, including the Gulf of California. Finally, its widespread abundance in bays and harbors suggests shipping is a likely transport mechanism.  相似文献   

11.
Host specificity is a key variable of the niche breath of parasites that can be an important determinant of a parasite’s ability to invade new areas. There is increasing evidence that many parasite species may comprise a variety of genetically variable lineages, which differ in host specificity and geographic range. In this study, we (1) explored the extent of diversity in the invasive parasitic barnacle Loxothylacus panopaei (Rhizocephala) infecting mud crabs (2) examined the geographic origin for the invasive lineage and (3) assessed if further southward spread of the parasite may be impeded. Along the US Atlantic coast, L. panopaei infects different hosts in its invaded range (Chesapeake Bay to north of Cape Canaveral) compared to one portion of the native range in Southeast Florida. This difference was reflected in genetic lineages on two independent loci, mitochondrial cytochrome oxidase I and nuclear cytochrome c. Both loci were concordant in that they showed one lineage infecting crabs of the genus Panopeus in the native range and one lineage infecting Eurypanopeus depressus and Rhithropanopeus harrisii hosts in the invaded range and in the Gulf of Mexico, thus indicating Gulf of Mexico populations as the most likely source of introduction into Chesapeake Bay. Interestingly, the nuclear marker resolved an additional lineage of parasites infecting panopeid hosts in the native range. All three parasite lineages were well supported, but a decision about species status must await further analyses. Since its introduction in the 1960s, the invasive L. panopaei lineage has expanded its range southward along the US Atlantic coast, now almost reaching the northern limit of native Panopeus-infecting lineages at Cape Canaveral, Florida. We hypothesized that parasite-free E. depressus in Southeast Florida, living in sympatry with infected panopeid populations, might be resistant to infection by the invasive lineage. Our infection experiments rejected this hypothesis, suggesting that any impediment to further southward range expansion might be expected from temperature regimes of the subtropical zoogeographic region south of Cape Canaveral.  相似文献   

12.
The Asian kelp Undaria pinnatifida was discovered in southern California in the spring of 2000, and by the summer of 2001 had been collected at several California sites from Los Angeles to Long Beach Harbors and Catalina Island as far north as Monterey Harbor. From its native range in the northwestern Pacific, Undaria has now been introduced to the northeastern and southwestern Atlantic and the southwestern and northeastern Pacific, through a combination of intentional transport for cultivation, accidental transport with oysters, as fouling on vessel hulls, and possibly other means. In the northeastern Pacific, water temperatures are suitable for its establishment from at least Baja California to British Columbia, where it is likely to grow well in sheltered and partially sheltered waters.  相似文献   

13.
The North Atlantic right whale (Eubalaena glacialis) is one of the world's most highly endangered baleen whales, with approximately 400–450 individuals remaining. Massachusetts Bay (MB) and Cape Cod Bay (CCB) together comprise one of seven areas in the Gulf of Maine where right whales seasonally congregate. Here, we report on acoustically detected presence of right whales in MB over a nearly 6 year period, July 2007–April 2013, a time of both rapid ocean warming throughout the Gulf of Maine and apparent changes in right whale migratory dynamics. We applied an automated detection algorithm to assess hourly presence of right whale “up‐calls” in recordings from a 19‐channel acoustic array covering approximately 4,000 km2 in MB. Over the survey, up‐calls were detected in 95% of 8 day periods. In each year, as expected, we observed a “peak season” of elevated up‐call detections in late winter and early spring corresponding to the season when right whales congregate to feed in CCB. However, we also saw an increase in right whale occurrence during time periods thought to be part of the “off‐season.” With the exception of 2009–2010, when acoustic presence was unusually low, the mean percent of hours in which up‐calls were detected increased every year, both during the peak season (from 38% in 2008 to 70% in 2012), and during the summer–fall season (from 2% in 2007 to 13% in 2012). Over the entire study, the peak season start date varied between 17 January and 26 February. Changes in right whale phenology in MB likely reflect broadscale changes in habitat use in other areas within the species range. This study demonstrates the value of continuous long‐term survey datasets to detect and quantify shifts in cetacean habitat use as environmental conditions change and the long‐term continued survival of right whales remains uncertain.  相似文献   

14.
Many benthic marine invertebrates show striking range disjunctions across broad spatial scales. Without direct evidence for endemism or introduction, these species remain cryptogenic. The common ragworm Hediste diversicolor plays a pivotal role in sedimentary littoral ecosystems of the North Atlantic as an abundant prey item and ecosystem engineer, but exhibits a restricted dispersal capacity that may limit connectivity at both evolutionary and ecological time scales. In Europe, H. diversicolor is subdivided into cryptic taxa and genetic lineages whose distributions have been modified by recent invasions. Its origin in the northwest Atlantic has not been adequately addressed. To trace the age and origin of North American ragworm populations, we analyzed mtDNA sequence data (COI) from the Gulf of Maine and Bay of Fundy (n=73 individuals) and compared our findings with published data from the northeast Atlantic. Our results together with previous data indicate that two species of the H. diversicolor complex have independently colonized the northwest Atlantic at least three different times, resulting in two distinct conspecific assemblages in the Bay of Fundy and Gulf of Maine (respectively) that are different from the species found in the Gulf of St. Lawrence. North American populations had significantly lower genetic diversity compared with populations in the northeast Atlantic, and based on patterns of shared identity, populations in the Bay of Fundy originated from the Baltic Sea and North Sea. Populations from the Gulf of Maine were phylogenetically distinct and most likely originated from unsampled European populations. Analyses of the North American populations revealed patterns of post‐colonization gene flow among populations within the Gulf of Maine and Bay of Fundy. However, we failed to detect shared haplotypes between the two regions, and this pattern of complete isolation corroborates a strong phylogeographic break observed in other species.  相似文献   

15.
Zooplankton were collected by vertical tows with 102 µm mesh at ten stations in Boston Harbor, Massachusetts Bay and Cape Cod Bay in February, March, April, June, August, and October, 1992. This study was part of a larger monitoring program to assess the effects of a major sewage abatement project, and sampling periods were designed around periods of major phytoplankton events such as the winter-spring diatom bloom, the stratified summer flagellate period, and the autumn transition from stratified to mixed waters. There was considerable seasonal variation in total zooplankton abundance, with minimal values in April (1929–11631 animals m–3) during a massive bloom of Phaeocystis pouchetii, and maximum values (67 316–261075 animals m–3) in August. There were no consistent trends of total abundance where any particular station had greater or lesser abundance than others over the entire year. Zooplankton abundance was dominated by copepods (adults + copepodites) and copepod nauplii (30.4–100.0% of total zooplankton, mean= 83.2%). Despite the large seasonal variation in zooplankton and copepod abundance, the copepod assemblage was dominated throughout the entire year by the small copepod Oithona similis, followed by Paracalanus parvus. Other less-abundant copepods present year-round were Pseudocalanus newmani, Temora longicornis, Centropages hamatus, C. typicus, and Calanus finmarchicus. Two species of Acartia were present, primarily in low-salinity waters of Boston Harbor: A. hudsonica during cold periods, and A. tonsa in warm ones. Eurytemora herdmani was also a subdominant in Boston Harbor in October. The potential role of zooplankton grazing in phytoplankton dynamics and bloom cycles in these waters must be considered in view of the overwhelming numerical dominance of the zooplankton by Oithona similis which may feed primarily as a carnivore. Furthermore, it seems unlikely that eutrophication-induced alteration of phytoplankton assemblages could cause significant trophic domino effects, reducing abundances of Calanus finmarchicus that are forage of endangered right whales seasonally utilizing Cape Cod Bay because C. finmarchicus has long been known to be a relatively unselective grazer, and most importantly, it is a trivial component of total zooplankton or total copepod abundance in these waters.  相似文献   

16.
During the summer of 1998 a new year class of the invasive European green crab, Carcinus maenas, appeared in Oregon and Washington estuaries as well as in northern California, USA, and on Vancouver Island, Canada. This invader was first discovered in San Francisco Bay almost a decade earlier and by 1995 it had spread to northern California. The coast-wide colonization event we studied in 1998 (El Niño cohort) was correlated with unusually strong north flowing coastal currents from September 1997 to April 1998. Larval transport by ocean currents from established populations to the south appeared to be the mechanism for the colonization. Crabs from the 1998-year class grew faster than counterparts from Maine and Europe, averaging 14 mm in carapace width in June, and 46 mm by September 1998. By the end of their second summer, males ranged from 52 to 80 mm in carapace width, and by fall of 2000 some males attained a carapace width of over 90 mm. The life span for C. maenasit in Oregon, Washington and British Columbia is estimated to be similar as in Europe and Maine: 4–6 years. Even though the initial colonists (98-year class) are dying of senescence, and coastal currents have not been favorable for larval transport from source populations in California, green crabs do persist in Oregon and Washington estuaries. It appears that local reproduction and recruitment in some years is high enough to keep this population from going extinct.  相似文献   

17.
The recent invasion of the red alga Heterosiphonia japonica in the western North Atlantic Ocean has provided a unique opportunity to study invasion dynamics across a biogeographical barrier. Native to the western North Pacific Ocean, initial collections in 2007 and 2009 restricted the western North Atlantic range of this invader to Rhode Island, USA. However, through subtidal community surveys, we document the presence of Heterosiphonia in coastal waters from Maine to New York, USA, a distance of more than 700 km. This geographical distribution spans a well-known biogeographical barrier at Cape Cod, Massachusetts. Despite significant differences in subtidal community structure north and south of Cape Cod, Heterosiphonia was found at all but two sites surveyed in both biogeographic provinces, suggesting that this invader is capable of rapid expansion over broad geographic ranges. Across all sites surveyed, Heterosiphonia comprised 14% of the subtidal benthic community. However, average abundances of nearly 80% were found at some locations. As a drifting macrophyte, Heterosiphonia was found as intertidal wrack in abundances of up to 65% of the biomass washed up along beaches surveyed. Our surveys suggest that the high abundance of Heterosiphonia has already led to marked changes in subtidal community structure; we found significantly lower species richness in recipient communities with higher Heterosiphona abundances. Based on temperature and salinity tolerances of the European populations, we believe Heterosiphonia has the potential to invade and alter subtidal communities from Florida to Newfoundland in the western North Atlantic.  相似文献   

18.
Electrophoretic surveys have demonstrated that populations of the sea anemone Metridium senile along the northeast coast of the United States are polymorphic at four enzyme loci. Phosphoglucose isomerase (PGI) has two alleles in most populations, phosphoglucomutase (PGM) has three alleles, and two leucine aminopeptidase loci have two common alleles each. Phosphoglucose isomerase displays clinal variation and an apparent association with environmental temperature. Phosphoglucomutase shows clinal variation north of Cape Cod for two of the three alleles, while the two leucine aminopeptidase loci are not clinal. All loci show a great deal of variation in populations on Cape Cod, but there is no apparent systematic pattern to this variation. Temperature may be a selective agent in the maintenance of the PGI and PGM clines, although other possibilities cannot presently be completely excluded.Supported by Grant T-4 from the Health Research and Services Foundation, NSF DEB77-14442, NIH GM25809, and NIH GM28024.  相似文献   

19.
Surveys were conducted along the northeast coast of the USA.between Portsmouth, NH, and the Chesapeake Bay in 1988 and 1990,to determine the population distribution of Aureococcus anophagefferens,the chrysophyte responsible for massive and destructive ‘browntides’ in Long Island and Narragansett Bay beginning in1985. A species-specific immunofluorescent technique was usedto screen water samples, with positive identification possibleat cell concentrations as low as 10–20 cells ml–1.Both years.A.anophagefferens was detected at numerous stationsin and around Long Island and Barnegat Bay, NJ, typically athigh cell concentrations. To the north and south of thus ‘center’,nearly half of the remaining stations were positive for A.anophagefferens,but the cells were always at very low cell concentrations. Manyof the positive identifications in areas distant from Long Islandwere in waters with no known history of harmful brown tides.The species was present in both open coastal and estuanne locations,in salinities between 18 and 32 practical salinity units (PSU).The observed population distributions apparently still reflectthe massive 1985 outbreak when this species first bloomed, giventhe number of positive locations and high abundance of A.anophagefferensin the immediate vicinity of Long Island. However, the frequentoccurrence of this species in waters far from this population‘center’ is disturbing. Aureococcus anophagefferensis more widely distributed than was previously thought. Numerousareas thus have the potential for destructive brown tides suchas those associated with the sudden appearance of the speciesin 1985.  相似文献   

20.
Recent collections of tetrasporangiate “Heterosiphonia” japonica Yendo from Watch Hill to Point Judith, Rhode Island, represent the first report of this nonnative alga in the western Atlantic. Native to the Pacific Ocean, this species was unintentionally introduced into European waters by 1984 and has subsequently invaded the eastern Atlantic Ocean widely from France to Norway and south into the Mediterranean Sea. Thus far, all western Atlantic collections of this species are confined to the outer coast of Rhode Island, and at present are not found in Narragansett Bay or in Long Island Sound along the Connecticut coast. Molecular and morphological studies confirm the identity of this newly introduced invasive species.  相似文献   

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