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Thermal habitat of striped bass (Morone saxatilis) in coastal waters of northern Massachusetts, USA, during summer
Abstract
Striped bass, Morone saxatilis, were captured and released with temperature-measuring data storage tags in Salem Sound, Massachusetts, to collect data on their thermal preferences in coastal and marine waters and to identify environmental factors that may influence temperatures experienced during their summer residence. Striped bass recaptured during summer of 2006 (21 of 151 releases) experienced a wide range of temperatures (6.5–28.0°C) while at-large for 1–53 days. Overall mean temperature and standard deviation selected by striped bass recaptured in Salem Sound during the longest commonly-shared duration of time (3–12 July) were 17.8 and 3.57°C, respectively. Comparison of temperature data between fish and 13 vertical arrays in Salem Sound revealed that striped bass experienced higher and more variable temperatures, and that daily changes in temperature actually experienced were unrelated to daily changes in surrounding ambient temperature. Regular cyclical changes in temperature of all striped bass and vertical arrays were identified as influences of the local tide, which contributed about a 2°C change in temperature, on average, over the complete cycle. Most striped bass appeared to limit their activities to depths shallower than the lower limit of the thermocline, above which temperatures generally exceed 9.0°C in Salem Sound. Therefore, it is likely that the vertical distribution of striped bass is restricted by the low temperatures below this depth. An implication of this finding is that the spatial distribution of striped bass may be defined coarsely by knowledge of the distribution of temperature in coastal areas.
... Striped bass migratory strategies are highly variable. Stocks at the southern extreme of their range exhibit riverine and estuarine residency, potentially avoiding marine thermal barriers to coastal migration and survival (Hess et al. 1999, Bjorgo et al. 2000, Nelson et al. 2010. Stocks between North Carolina and New Brunswick exhibit long distant marine migrations (Setzler-Hamilton et al. 1980, Waldman et al. 1990, Rulifson et al. 2008, Douglas & Chaput 2011, Andrews et al. 2019a, however, otolith microchemistry analyses indicate the presence of riverine and estuarine resident contingents within some stocks (Secor & Piccoli 1996). ...
... Abundant tagging data from the striped bass stock in the Shubenacadie River, Nova Scotia, indicates fish predominately remain in Minas Basin (Broome 2014). We suggest that striped bass have established isolated, local populations in eastern Nova Scotia like those at the southern extreme of their range (Hess et al. 1999, Bjorgo et al. 2000, Nelson et al. 2010, which complements our understanding of the species biology in the Canadian Maritimes and may be associated with common behavior among stocks near the extents of its range. Critical habitat for establishment of a stock in the Maritimes includes an appropriate wintering site, a spawning site and availability of desired prey. ...
The occurrence of striped bass outside the immediate vicinity of known spawning rivers in Canada is neither widely understood nor well studied. Striped bass in Canada are managed and assessed within three distinct units, the Bay of Fundy, the Gulf of St. Lawrence, and the St. Lawrence River; but stocks that may occur outside these units are unrecognized. We document a previously unstudied aggregation of striped bass in the Mira River estuary (MRe), Cape Breton Island (46° 01′N, 60° 03′W), a location on the east coast of Nova Scotia omitted from present management units but which has been long reported to host an aggregation. From July 2012 to November 2014, 62 striped bass within MRe were sampled and 31 were surgically implanted with VEMCO acoustic transmitters. Striped bass ranged in size from 31.6 to 125.0 cm total length and age 3 to 24 years. Acoustic telemetry from 2012 to 2015 elucidated residency and fidelity to the MRe with mid-estuary overwintering every year, freshwater residency of the adult population during spring, and a summer through autumn aggregation in the lower estuary. Of the 31 acoustically tagged striped bass, 24 remained in MRe throughout the study, six exhibited mid-summer departures to the Atlantic Ocean but returned by mid-autumn, while one left the MRe and was never detected again. Mira River SB with acoustic tags were never detected at nearby Ocean Tracking Network telemetry infrastructure. Striped bass stocks exhibit similar residency and fidelity patterns to their natal rivers and estuaries elsewhere in its Atlantic coast range which suggests the Mira River aggregation constitutes a possible distinct stock yet unrecognized by Canadian fisheries managers.
... For example , Pacific salmonids, Oncorhynchus nerka, O. keta and O. gorbuscha , have been found to differentially utilize thermal habitats during the course of ontogenetic development (Morita et al., 2010). Striped bass, Morone saxatilis, maintains its thermal regime in respect to ambient thermal habitats, which likely affects its access to estuarine prey species (Nelson et al., 2010). Atlantic salmon, Salmo salar, adult growth may be influenced by the quantity of overwintering thermal habitat (Friedland and Todd, 2011). ...
... For example, Pacific salmonids, Oncorhynchus nerka, O. keta and O. gorbuscha, have been found to differentially utilize thermal habitats during the course of ontogenetic development ( Morita et al., 2010). Striped bass, Morone saxatilis, maintains its thermal regime in respect to ambient thermal habitats, which likely affects its access to estuarine prey species ( Nelson et al., 2010). Atlantic salmon, Salmo salar, adult growth may be influenced by the quantity of overwintering thermal habitat ( Friedland and Todd, 2011). ...
... Within this broader migration pattern, striped bass vary in fine-scale movements by location, populations, and individuals. A variety of environmental variables, such as salinity (Able et al. 2012), temperature (Nelson et al. 2010), dissolved oxygen (Kraus et al. 2015), age (Callihan et al. 2014), density (Callihan et al. 2014), and habitat structure (e.g., sandbars, channel networks) (Kennedy et al. 2016), can influence finer-scale movements. Furthermore, studies have widely documented migratory Bcontingents^, which are defined as groups of individuals belonging to the same population that adopt different migratory patterns (Secor 1999). ...
Movement dynamics of nonnative species can change in new environments and differ from native populations. It has been more than 100 years since striped bass (Morone saxatilis) were introduced to the Sacramento-San Joaquin River system in California from the US east coast. Acoustic telemetry from 2011 to 2015 was used to examine striped bass seasonal residence patterns in their nonnative range across three regions—bay, delta and rivers, and the effect of fish length and release river (Sacramento River [SR] vs. Feather River [FR]) on movement. In spring, SR striped bass (n = 52) increased travel speed by 39% and river residence by 63% relative to other seasons, which is consistent with spawning migrations. In summer, SR striped bass spent the most time in the bay (mean = 28.2 ± 30.9 days) relative to other seasons and across regions. In winter, 87% of striped bass were detected in the delta over 42% in the bay and 25% in the river. Release river also affected movement behaviors—FR striped bass (n = 11) spent more time in the river in all seasons compared to SR bass. Striped bass with sufficient tag life (n = 17) traveled farther distances in 365 days (mean = 1248 ± 405 km, range: 641–2212 km) with increasing fish length. Seasonal patterns observed appeared to follow seasonal prey sources throughout the San Francisco Estuary. Individual behaviors, however, were highly variable, and this flexibility may be an important trait that has allowed striped bass to persist in their nonnative range.
... Massachusetts is unique in that a major portion of the migratory stocks is believed to summer in state waters (based on recreational catches; ASMFC 2016) likely due to abundant prey resources (Nelson et al. 2003) and optimal water temperatures (Nelson et al. 2010). As a result, major fluctuations in abundance of the migratory stocks have historically impacted the viability of the commercial fishery for Striped Bass in Massachusetts (Bigelow and Welsh 1924, Koo 1970, Richards and Rago 1999. ...
Since the arrival of Pilgrims in 1620, Morone saxatilis (Striped Bass) has been an important commercial fish species for residents of Massachusetts. Early attempts by the Plymouth Colony to develop fishery commerce by selling Striped Bass products to Spain failed. Viable domestic markets for Striped Bass were established by the 18 th century and continue to present day. Application of laws to control the commercial harvest of Striped Bass to address local declines in abundance first appeared in the Massachusetts Acts and Resolves in the late 18 th century, and most laws restricted the taking of Striped Bass by seines. In 1945, a temporary Massachusetts law prohibiting the taking of Striped Bass by any method other than hook-and-line was made permanent. More-restrictive size and quota regulations were not imposed until the early 1980s as interstate conservation efforts responded to the declining trends in coastal stocks. In present day, the Striped Bass commercial fishery in Massachusetts is regulated by minimum size and quotas established under the Atlantic States Marine Fisheries Commission's Striped Bass Management Plan and by state no-take days and daily bag limits.
... %N = percent composition by number, n = total number of prey items counted, %FO = percent frequency of occurrence, and * = not determined. temperatures (Nelson et al. 2010). Although some fishes briefly utilize habitats with potentially lethal temperatures for foraging (Stauffer et al. 1976), thermally constrained Striped Bass avoid crossing thermoclines to forage on prey 1-2 m away (Coutant 1985). ...
... %N = percent composition by number, n = total number of prey items counted, %FO = percent frequency of occurrence, and * = not determined. temperatures (Nelson et al. 2010). Although some fishes briefly utilize habitats with potentially lethal temperatures for foraging (Stauffer et al. 1976), thermally constrained Striped Bass avoid crossing thermoclines to forage on prey 1-2 m away (Coutant 1985). ...
Overwintering Morone saxatilis (Striped Bass) often aggregate in waters heated by the warm-water discharge of power plants. In these areas, fishes are susceptible to cold shock during winter disruptions of power generation when the water quickly drops in temperature. We collected 98 Striped Bass from a suspected cold-shock mortality event at a power plant in Pictou Harbour, NS, Canada, in January 2013 and herein describe their size, age structure, and diet. The specimens ranged from 11.8 to 60.2 cm TL and were 1–5 years of age. Fifteen percent of their stomachs contained food, and Striped Bass and Apeltes quadracus (Fourspine Stickleback) were the only prey species identified. The goal of this study was to report on the mortality event as a likely recurring source of overwintering mortality for Striped Bass in the southern Gulf of St. Lawrence, a population designated by the Committee on the Status of Endangered Wildlife in Canada to be of special concern.
... Migratory striped bass can remain within a single target estuary for several months in the summer (Pautzke et al. 2010), where they feed intensively (>85% of 799 striped bass sampled had food in their stomachs; Ferry and Mather 2012). Although striped bass distribution has been associated with depth (e.g., Ng et al. 2007), temperature (e.g., Nelson et al. 2010), salinity (Able et al. 2012), and dissolved oxygen (e.g., Coutant 1985), models including only these regularly occurring fish habitat variables have limited predictive capabilities. Larger scale anthropogenic features [e.g., docks, landings, artificial reefs, oyster reefs (Harding and Mann 2003); sandbars and submerged woody debris, shorelines, dropoffs, channels (Ng et al. 2007); and confluences (Tupper and Able 2000)] have only been anecdotally linked to striped bass distribution. ...
Understanding environmental drivers of spatial patterns is an enduring ecological problem that is critical for effective biological conservation. Discontinuities (ecologically meaningful habitat breaks), both naturally occurring (e.g., river confluence, forest edge, drop-off) and anthropogenic (e.g., dams, roads), can influence the distribution of highly mobile organisms that have land- or seascape scale ranges. A geomorphic discontinuity framework, expanded to include ecological patterns, provides a way to incorporate important but irregularly distributed physical features into organism–environment relationships. Here, we test if migratory striped bass (Morone saxatilis) are consistently concentrated by spatial discontinuities and why. We quantified the distribution of 50 acoustically tagged striped bass at 40 sites within Plum Island Estuary, Massachusetts during four-monthly surveys relative to four physical discontinuities (sandbar, confluence, channel network, drop-off), one continuous physical feature (depth variation), and a geographic location variable (region). Despite moving throughout the estuary, striped bass were consistently clustered in the middle geographic region at sites with high sandbar area, close to channel networks, adjacent to complex confluences, with intermediate levels of bottom unevenness, and medium sized drop-offs. In addition, the highest striped bass concentrations occurred at sites with the greatest additive physical heterogeneity (i.e., where multiple discontinuities co-occurred). The need to incorporate irregularly distributed features in organism–environment relationships will increase as high-quality telemetry and GIS data accumulate for mobile organisms. The spatially explicit approach we used to address this challenge can aid both researchers who seek to understand the impact of predators on ecosystems and resource managers who require new approaches for biological conservation.
... Thermal habitat is finding application in marine environments as it relates to the definition of niche space. For example, Pacific salmonids display age-related thermal habitat use (Morita et al. 2010) and the vertical distribution of striped bass (Morone saxatilis) appears limited by coastal thermal habitat (Nelson et al. 2010). To view thermal habitat as a constraint on salmon growth, the habitat would have to be limiting in a compensatory fashion. ...
There has been a systematic change in the weight at age of Atlantic salmon (Salmo salar L.) in the Northwest Atlantic that is related to climate variability. This relationship emerged from analyses of broad-scale measures of ocean surface thermal habitat, which show that expansion of the area bounding 4–8°C is associated with greater growth. To further elucidate the effect of the environment on salmon growth, time series of sea surface temperature (SST), sea ice coverage, chlorophyll concentration, net primary production and zooplankton abundance were examined temporally and spatially in relation to changes in the weight of salmon. SST and zooplankton data were extracted from in situ analyses, whereas sea ice and chlorophyll-based measures of productivity were collected with satellite sensors. Salmon growth was found to be unrelated to productivity at the base of the food chain but highly associated with thermal regime during winter and spring. Warming conditions during specific segments of the salmon life cycle have been associated with poor adult recruitment; yet, warming during others is beneficial to salmon growth and is assumed to increase reproductive output of spawning fish. Despite these positive influences, climate change will continue to erode the viability of salmon populations while the negative effects of warming on survivorship outweigh the benefits of any increase in reproductive output related to growth.
Technological developments over the last 20 years have meant that telemetry studies have used a variety of techniques, each with different levels of accuracy and temporal resolution. This presents a challenge when combining data from these different tracking systems to obtain larger sample sizes or to compare habitat use over time. In this study, we used a Bayesian state-space modelling approach to integrate tracking data from multiple tag types and standardise position estimates while accounting for location error. Harbour seal (Phoca vitulina) telemetry data for the Moray Firth, Scotland, were collated from three tag types: VHF, Argos satellite and GPS–GSM. Tags were deployed on 37 seals during 1989 to 2009 resulting in 37 tracks with a total of 2886 tracking days and a mean duration of 87 days per track. A state-space model was applied to all of the raw tracks to provide daily position estimates and a measure of the uncertainty for each position. We used this standardised tracking dataset to model their habitat use and preference, which was then scaled by the population size estimated from haul-out counts to give an estimate of the absolute number of harbour seals using different parts of the Moray Firth. As expected for a central place forager, harbour seals most frequently occurred in areas close to their inshore haul-out sites. However, our analyses also demonstrated consistent use of offshore foraging grounds, typically within 30 km of haul-out sites in waters < 50 m deep. The use of these statistical models to integrate and compare different datasets is especially important for assessing longer-term responses to environmental variation and anthropogenic activities, allowing management advice to be based upon datasets that integrate information from all available tracking technologies.
Bioenergetics models for striped bass (Morone saxatilis), bluefish (Pomatomus saltatrix), and weakfish (Cynoscion regalis) were developed from laboratory experiments on metabolism and consumption. Size-specific rates of consumption and metabolism were similar for bluefish and weakfish and higher than those for striped bass. Temperature effects on maximum consumption rate (Cmax) differed with fish size. Overall, the growth physiology of the three species appeared to be related to the water temperatures encountered during estuarine residency and production. -from Authors
Seasonal, age-class, and population-level changes in diet and consumption demand of prey by striped bass residing in coastal waters of northern Massachusetts were investigated to determine their potential predatory impact on ecologically- and economically-important prey species. Most consumption by individual striped bass of ages 3-8 came from crustaceans and fish. More crusta - ceans (50-78% of total consumption) than fish were consumed during June-July, while more fish (52-88% of total consumption) than crustaceans were consumed during August-September. Rock crabs Cancer irroratus and American lobsters Homarus americanus became more important to the production of striped bass as bass aged, but Atlantic menhaden Brevoortia tyrannus became less important. Together, the biomass of prey consumed by all age-classes in 2000 totaled over 5 575 t. Atlantic menhaden accounted for 29% of the total biomass consumed, followed by rock crabs (18%), American lobster (11%), and Atlantic herring Clupea harengus (3%). On a numerical basis, striped bass consumed seasonally over 3, 1 940, and 965 times the numbers of lobsters, rock crabs, and men- haden, respectively, taken annually by regional and statewide fisheries, suggesting striped bass may exert considerable predation pressure on these prey populations.
Populations of striped bass Morone saxatilis occur in three regions of Atlantic Canada: the St. Lawrence River and estuary in Quebec; the Gulf of St. Lawrence from Chaleur Bay through Northumberland Strait; and rivers in New Brunswick and Nova Scotia draining into the Bay of Fundy. At least nine rivers are known or believed to sustain spawning populations: the St. Lawrence River (where the spawning stock may be extirpated); the Nepisiguit River in Chaleur Bay; the Tabusintac, Miramichi, Kouchibouguac, and Richibucto rivers in the western Gulf of St. Lawrence; the Saint John and Annapolis rivers in the outer Bay of Fundy; and the Shubenacadie–Stewiacke river system in the inner Bay of Fundy. Historically, commercial striped bass landings in Atlantic Canada were lower than those of the U.S. eastern seaboard, the largest landings being made in New Brunswick. Angling catches are substantial but difficult to verify. Spawning occurs in tidal streams several weeks after ice leaves the system. Adults exhibit regional and long-distance summer migration but seek freshwater refugia for overwintering. Studies of growth, population age structures, comparative total instantaneous mortality rates, meristic and morphometric characters, and parasites, combined with tag returns, strongly suggest that Bay of Fundy rivers, specifically the Annapolis, Shubenacadie, and Saint John, contain stocks that are mixed with U.S. fish in most years. Bay of Fundy fish apparently participate in the striped bass coastal migration on the eastern seaboard, whereas populations in Gulf of St. Lawrence rivers appear to be localized. Anecdotal information from commercial and angling catches suggests more spawning–overwintering populations occur than are known to science. Periodic population assessments should be conducted to provide the information necessary for knowledgeable management of the species in eastern Canada.
Stomach contents of striped bass (Morone saxatilis) collected from three coastal regions of Massachusetts during June-September in 1997-2000 were examined for patterns in prey composition and body size related to coastal region, time period of capture, foraging habitat, and length of striped bass. Together fish (mostly Clupeidae, Menidia sp., and Ammodytes sp.) and crustaceans (mostly Crangon septemspinosa, Cancer irroratus, and Homarus americanus) dominated the diet of striped bass by both weight (91-95%) and number (87-97%), and had a high frequency of occurrence (42-66%) in the stomachs. Similarity in prey taxa among coastal regions was moderate to high (58-74%). Cluster analysis and ordination techniques grouped the stomach contents from each region by capture period, habitat, and 50 mm striped bass length interval. The stomach contents of bass ≤675 mm total length (TL) collected during August-September from estuaries and rocky shoreline habitats in the North Shore and Cape Cod Bay regions had a higher average percentage of menhaden (Brevoortia tyrannus) by weight than found in similar-sized bass collected during June-July from the same habitats. Also, in the North Shore area, striped bass ≤675 mm TL sampled in rocky shorelines contained a higher average percentage of Cancer irroratus by weight than similar-sized bass taken in estuaries. Bass ≥675 mm TL in rocky habitats consumed more Homarus americanus than smaller bass residing in this same habitat. The size distribution of the dominant fishes and crabs (Ammodytes sp., B. tyrannus, Cancer irroratus, and Carcinus maenus) consumed by striped bass was related to bass body size. Benthic prey were found to be a major component of the diet of striped bass in Massachusetts coastal waters.
Stensholt, B. K. 2001. Cod migration patterns in relation to temperature: analysis of storage tag data. - ICES Journal of Marine Science, 58: 770-793. Bivariate time-series of depth (pressure) and temperature with two-hour intervals from 19-data storage tags (DST) attached to adult Northeast Arctic cod (Gadus morhua L.) released from mid-March are analysed. Interplay between migration behaviour, physiological limitation factors, environment, and ecology in the Barents Sea is investigated using geometrical and statistical methods. Thermo-stratification is ident- ified using r(t), the ratio between temperature and depth change over each record interval. Vertical activity, act(a), in relation to physiological limitations to pressure change is measured with the ratio of the daily depth range to the free vertical range. Cycles are detected by spectral analysis. The analysis supports conclusions from large-scale studies. Cod migrate along stable thermal paths until they reach a front area (or feeding ground), where the vertical activity increases and the records of depth, temperature, and r(t) change pattern, level and range. The (semi-) diurnal vertical migration (DVM) occurs seasonally in some fish, mainly in areas with large tempera- ture gradient. In 11 out of 12 tags where DVM is detected, this occurs during summer and autumn. In seven out of 11 tags where semi-diurnal tidal cycles are detected in the temperature series together with a significant reduction in vertical migration, this occurs during April. In some tags diurnal or semi-diurnal cycles appear in both depth and temperature series. 2001 International Council for the Exploration of the Sea
Bioenergetics models for striped bass (Morone saxatilis), bluefish (Pomatomus saltatrix), and weakfish (Cynoscion regalis) were developed from laboratory experiments on metabolism and consumption. Size-specific rates of consumption and metabolism were similar for bluefish and weakfish and higher than those for striped bass. Temperature effects on maximum consumption rate (Cmax) differed with fish size. Cmax of young fish (30 g) increased with temperature, then declined rapidly at higher temperatures; Cmax for larger fish of all three species (100–3000 g) increased rapidly to the maximum rate, but leveled off at higher (25–30 °C) temperatures. Results of Cmax experiments suggest that extrapolation of the temperature dependency of small fish to larger fish, as is commonly done, may misrepresent potential growth at higher temperatures. Independent model validation using laboratory experiments found consumption estimates (from growth) to be within −1.4 to +4.5% of known values for all species at temperatures above 19 °C; however, at 6.9°C consumption by striped bass was overestimated by 20–46%. Model estimates of growth (from consumption) were within −7.1 to +30.1% of known values in all validations. Overall, the growth physiology of the three species appeared to be related to the water temperatures encountered during estuarine residency and production.
Adult striped bass Morone saxatilis (n = 61; 597-914 mm total length) were captured by hook and line throughout Lake Murray, South Carolina, and by electrofishing in the Greenwood Dam tailrace and upper Saluda River above Lake Murray, implanted with temperature-sensitive radio transmitters, and tracked biweekly. During late winter-early spring, striped bass were concentrated in the upstream portions of the reservoir. By midsummer, they were primarily located in the lower embayment of the reservoir, but several fish remained in the tailrace of the upstream dam as well as in a thermal refuge in the Saluda River. After the reservoir began to cool in fall, fish dispersed from the lower embayment and moved upstream toward the headwaters of the reservoir, where they had been captured the previous spring. Several fish returned to locations within 10 m of their original capture locations. Mean movement rates were lowest in winter and summer and highest in spring and fall. Low movement rates in summer were associated with a severe reduction of suitable habitat. In addition to the standard biweekly sampling, a 7.5-km section of the lower embayment of Lake Murray was searched every 2 h over a continuous 48-h period from 10 to 12 August 2000. During this period, striped bass were observed to use the same areas on a seasonal basis as they did on a diel basis. However, mean hourly rates of movement were greater than the movement rates calculated for the normal 2-week interval between samples. Changes in location between biweekly samples may not indicate displacement but rather only randomly chosen locations in normal use areas.
The only anesthetic registered in North America for use in fisheries science is 3-aminobenzoic acid ethyl ester methanesulfate (tricaine or MS-222). Although MS-222 is a very effective anesthesia for several fish species, its application in the field is limited because U.S. Food and Drug Administration guidelines demand a 21-d withdrawal period after exposure to MS-222 before fish can be released and enter the food chain. As a consequence, carbon dioxide (CO2) has been used as a substitute anesthetic; however, induction and recovery times with CO2 are long, and anesthesia is shallow in comparison with MS-222. We compared the efficacy of MS-222 to that of clove oil, a naturally occurring substance, for use as an anesthetic for juvenile and adult rainbow trout Onchorhynchus mykiss. Clove oil was as effective as MS-222 in inducing anesthesia in both age-groups. Furthermore, exposure to either clove oil or MS-222 at the concentrations tested was not detrimental to critical swimming speed of juvenile or adult rainbow trout. We propose that clove oil be considered as an alternative to MS-222 for use as a fish anesthetic.
Electronically tagged juvenile Pacific bluefin, Thunnus orientalis, were released off Baja California in the summer of 2002. Time-series data were analyzed for 18 fish that provided a record of 380 ± 120 days (mean ± SD) of ambient water and peritoneal cavity temperatures at 120 s intervals. Geolocations of tagged fish were estimated based on light-based longitude and sea surface temperature-based latitude algorithms. The horizontal and vertical movement patterns of Pacific bluefin were examined in relation to oceanographic conditions and the occurrence of feeding events inferred from thermal fluctuations in the peritoneal cavity. In summer, fish were located primarily in the Southern California Bight and over the continental shelf of Baja California, where juvenile Pacific bluefin use the top of the water column, undertaking occasional, brief forays to depths below the thermocline. In autumn, bluefin migrated north to the waters off the Central California coast when thermal fronts form as the result of weakened equatorward wind stress. An examination of ambient and peritoneal temperatures revealed that bluefin tuna fed during this period along the frontal boundaries. In mid-winter, the bluefin returned to the Southern California Bight possibly because of strong downwelling and depletion of prey species off the Central California waters. The elevation of the mean peritoneal cavity temperature above the mean ambient water temperature increased as ambient water temperature decreased. The ability of juvenile bluefin tuna to maintain a thermal excess of 10°C occurred at ambient temperatures of 11–14°C when the fish were off the Central California coast. This suggests that the bluefin maintain peritoneal temperature by increasing heat conservation and possibly by increasing internal heat production when in cooler waters. For all of the Pacific bluefin tuna, there was a significant correlation between their mean nighttime depth and the visible disk area of the moon.
Fish aggregations at fronts may be caused by either increased food availability or better thermal conditions at the front,
but a quantitative evaluation of the effects of fronts on fish has yet to be done. Bioenergetics models were used to evaluate
the growth rate potential of a cool-water fish, the chinook salmon (Oncorhynchus tshawytscha), and a warm-water fish, the striped bass (Morone saxatilis), across thermal fronts of different temperatures and prey concentrations. The distributions of growth rate potentials across
these fronts depended on fish physiology, the temperatures encompassed by the front, and prey distributions across the front.
When food was distributed uniformly across the front, the growth rates of both species were highest at their optimal temperatures,
if sufficient prey was available. Lower temperatures were better for growth if prey availability was low. Increased food availability
at the front enhanced fish growth rate potential at the front. Actual growth rates depended on whether the fish behaviorally
selected habitats by temperature, food, or growth rate potential. Results illustrate that prey patchiness and the nonlinearities
inherent in the relationsip of fish growth to temperature and prey availability must be considered in order to evaluate how
a population of fish might respond to a front and how the front might affect fish growth and production.
In the early 1980s, a strategy for graphical representation of multivariate (multi-species) abundance data was introduced into marine ecology by, among others, Field, et al. (1982). A decade on, it is instructive to: (i) identify which elements of this often-quoted strategy have proved most useful in practical assessment of community change resulting from pollution impact; and (ii) ask to what extent evolution of techniques in the intervening years has added self-consistency and comprehensiveness to the approach. The pivotal concept has proved to be that of a biologically-relevant definition of similarity of two samples, and its utilization mainly in simple rank form, for example ‘sample A is more similar to sample B than it is to sample C’. Statistical assumptions about the data are thus minimized and the resulting non-parametric techniques will be of very general applicability. From such a starting point, a unified framework needs to encompass: (i) the display of community patterns through clustering and ordination of samples; (ii) identification of species principally responsible for determining sample groupings; (iii) statistical tests for differences in space and time (multivariate analogues of analysis of variance, based on rank similarities); and (iv) the linking of community differences to patterns in the physical and chemical environment (the latter also dictated by rank similarities between samples). Techniques are described that bring such a framework into place, and areas in which problems remain are identified. Accumulated practical experience with these methods is discussed, in particular applications to marine benthos, and it is concluded that they have much to offer practitioners of environmental impact studies on communities.
During 1973, 1974, and 1975 movements of 33 striped bass [Morone saxatilis (Walbaum)] in the Savannah River, Georgia were followed through the use of ultrasonic and radio transmitters. During March through May striped bass congregate and spawn in a tidally influenced, relatively shallow, small branch of the river (Little Back River) near Savannah, Georgia, about 30 km upstream from the river mouth. During the spawning season striped bass do not exhibit any specific movement pattern, but remain in this particular sector of the river. Immediately after spawning, all tracked fish moved upstream, some as far as 301 km from the spawning area. Fish remained in the upstream areas at least 4 months. We detected no fish moving downstream during this period. Our data and those from previous work strongly suggest that individuals in this population of striped bass spend the majority, if not all, of their lives in the Savannah River.
This paper is not subject to U.S. copyright. The definitive version was published in Fishery Bulletin 107 (2009): 329-338. For most migratory fish, little is known about the location and size of foraging areas or how long individuals remain in foraging areas, even though these attributes may affect their growth, survival, and impact on local prey. We tested whether striped bass (Morone saxatilis Walbaum), found in Massachusetts in summer, were migratory, how long they stayed in non-natal estuaries, whether observed spatial patterns differed from random model predictions, whether fish returned to the same area across multiple years, and whether fishing effort could explain recapture patterns. Anchor tags were attached to striped bass that were caught and released in Massachusetts in 1999 and 2000, and recaptured between 1999 and 2007. In fall, tagged striped bass were caught south of where they were released in summer, confirming that fish were coastal migrants. In the first summer, 77% and 100% of the recaptured fish in the Great Marsh and along the Massachusetts coast, respectively, were caught in the same place where they were released. About two thirds of all fish recaptured near where they were released were caught 2–7 years after tagging. Our study shows that smaller (400–500 mm total length) striped bass migrate hundreds of kilometers along the Atlantic Ocean coast, cease their mobile lifestyle in summer when they use a relatively localized area for foraging (<20 km2), and return to these same foraging areas in subsequent years. This project was administered through the Massachusetts Cooperative Fish and Wildlife Research Unit. The Massachusetts Cooperative Fish and Wildlife Research Unit is an association among the U.S. Geological Survey; University of Massachusetts Department of Natural Resources Conservation; Massachusetts Division of Marine Fisheries; Massachusetts Division of Fisheries and Wildlife, and the Wildlife Management Institute.
Ectothermic vertebrates respond to the temperature of their habitat in a manner that is remarkably similar to their response to more traditional ecological resources such as food. We review the response to temperature primarily from literature on fishes in terms of ecological concepts related to niche theory and competition. The width of the fundamental thermal niche is about 4°C when measured by a mean plus and minus one standard deviation of the distribution of temperature occupied in a laboratory gradient. Fish of temperate freshwater appear to fall into three thermal guilds along the temperature resource axis —cold, cool, and warm water fishes. Realized thermal niches are similar in central tendency to fundamental niches, but niche width appears to be more narrow for the realized niche in limited sample data. The success of interference competition for space with preferred temperature is tied to social dominance in a manner analogous to food competition. Thermal niche shifts in the face of interspecific competition for preferred temperature appear supported by one laboratory study. Exploitation competition in respect to temperature seems nebulous. If animals successfully compete for their thermal niche, growth and perhaps other measures of fitness are maximized. Cost/benefit models for thermal resources and food resources lead to similar predictions about resource use. We suggest that viewing temperature and other niche axes in the way ecologists have viewed food resources would be useful.
The analysis of univariate or multivariate time series provides crucial information to describe, understand, and predict climatic variability. The discovery and implementation of a number of novel methods for extracting useful information from time series has recently revitalized this classical field of study. Considerable progress has also been made in interpreting the information so obtained in terms of dynamical systems theory. In this review we describe the connections between time series analysis and nonlinear dynamics, discuss signal- to-noise enhancement, and present some of the novel methods for spectral analysis. The various steps, as well as the advantages and disadvantages of these methods, are illustrated by their application to an important climatic time series, the Southern Oscillation Index. This index captures major features of interannual climate variability and is used extensively in its prediction. Regional and global sea surface temperature data sets are used to illustrate multivariate spectral methods. Open questions and further prospects conclude the review.
Adult striped bass Morone saxatilis (N = 30, 656–906 mm total length) were captured by electrofishing during January–March 1998 in the Combahee River, South Carolina, and fitted with radio transmitters. Their exact locations were recorded biweekly through December. From January to early April, striped bass were located in the tidally influenced lower region of the river in water temperatures ranging from 9°C to 18°C. The fish then moved an average of 38.5 km upstream from late April to the end of May when water temperatures ranged from 18°C to 26°C. Striped bass remained in the upper region of the river from late May to September when water temperatures were as much as 5°C lower than in the river's lower regions. Striped bass began to move downstream and were spread throughout the river during September and October in water temperatures ranging from 19°C to 27°C. Combahee River striped bass appear to follow a migratory pattern typical of other southern striped bass stocks. Habitat preference appears to be strongly influenced by temperature. Combahee River temperatures are stable and remain close to the preferred temperatures of striped bass during summer extremes. Therefore, unlike northern populations, southern populations are more likely to remain within riverine habitat during the summer months. Discrete thermal refugia, such as springs, apparently are not used or are absent in the Combahee River. It is possible that striped bass in the Combahee River depend on the entire upper region of the river as a thermal refuge.
Subadult striped bass, Morone saxatilis, tagged with temperature-sensing ultrasonic transmitters in April-October and monitored in freshwater lakes generally occupied waters of 20-24 C, when these temperatures were available. When they were not (spring and fall), fish occupied nearly the warmest water available at depths >1.5 m. Excursions of less than 2 minutes duration to warmer and to cooler water than was generally occupied were common in spring and summer. A thermal niche for subadult striped bass of 20-24 C centering near 22 C, as suggested by these results, would have important implications for managing this species in fresh water.
Adult striped bass Morone saxatilis (N = 30, 656-906 mm total length) were captured by electrofishing during January-March 1998 in the Combahee River, South Carolina, and fitted with radio transmitters. Their exact locations were recorded biweekly through December. From January to early April, striped bass were located in the tidally influenced lower region of the river in water temperatures ranging from 9°C to 18°C. The fish then moved an average of 38.5 km upstream from late April to the end of May when water temperatures ranged from 18°C to 26°C. Striped bass remained in the upper region of the river from late May to September when water temperatures were as much as 5°C lower than in the river's lower regions. Striped bass began to move downstream and were spread throughout the river during September and October in water temperatures ranging from 19°C to 27°C. Combahee River striped bass appear to follow a migratory pattern typical of other southern striped bass stocks. Habitat preference appears to be strongly influenced by temperature. Combahee River temperatures are stable and remain close to the preferred temperatures of striped bass during summer extremes. Therefore, unlike northern populations, southern populations are more likely to remain within riverine habitat during the summer months. Discrete thermal refugia, such as springs, apparently are not used or are absent in the Combahee River. It is possible that striped bass in the Combahee River depend on the entire upper region of the river as a thermal refuge.
"How do the oceans work?" To help you find the answers, Trujillo and Thurman present in-depth discussions of oceanographic concepts and demystify the science even for non-science students. Their systems approach highlights the relationship between oceanographic phenomena and how those phenomena affect other Earth systems. Scientific information from geology, chemistry, physics, and biology combine to illustrate how each of these disciplines relates to the ocean.
Telemetry techniques were used to evaluate relationships between water quality and distribution of adult striped bass Morone saxatilis during an 18-month period in Watts Bar Reservoir, Tennessee. Distribution and movements of fish were influenced by water temperature and dissolved oxygen concentration. During winter and early spring, temperature was vertically and horizontally uniform, and striped bass were relatively mobile and occurred in both tributary arms as well as in the main body of the reservoir. As the reservoir warmed in summer, fish were less mobile and progressively limited to areas in the tributary arms where temperature was less than 24 C and dissolved oxygen exceeded 4 mg/liter. Parts of the tributary arms of Watts Bar Reservoir provided such areas due to hypolimnetic discharges from upstream impoundments and groundwater inflows. Striped bass were restricted to these areas until late fall, when the entire reservoir cooled and again was nearly isothermal. Knowledge of relationships between striped bass habitat use and water quality is useful for fishery management and resource protection for reservoirs; an example is provided for Watts Bar Reservoir.
Researchers have described the temperatures selected by landlocked striped bass Morone saxatilis in different locales throughout the USA. However, seasonally low concentrations of dissolved oxygen (DO) in many systems prevented striped bass from using the cool waters (<22°C) they may have preferred. In Melton Hill Reservoir, a 92-km-long impoundment on the Clinch River in east Tennessee, 15 adult striped bass were tagged with temperature-sensing radio tags and tracked for an average of 418 d in 1999–2000. Cold, hypolimnetic discharges from an upstream dam and heated discharge from a steam-generating electric facility near the midpoint of this run-of-the-river reservoir provided a broad range of temperatures in most seasons, and hypoxic habitats were uncommon even during stratification. The mean temperature occupied by striped bass varied seasonally (repeated-measures analysis of variance, P < 0.0001) and was highest in summer (17.5°C), intermediate in spring and fall (15.4–16.9°C), and lowest in winter (13.0°C). The mean and modal temperatures occupied during the growing season (May–October 1999) were 17.5°C and 19.0°C, respectively; 30% of the observations were between 9°C and 15°C. These data indicate that the fundamental thermal niche of adult landlocked striped bass may be lower than literature estimates. These results also represent the first unbiased field estimates of the influence of season on the thermal ecology of adult striped bass. The thermal characteristics of habitats considered optimal in habitat suitability index models for adult landlocked striped bass (i.e., 18– 24°C) should be revised to include cooler waters.
We evaluated summer water temperatures, dissolved oxygen concentrations, distribution of striped bass Morone saxatilis subadults and adults, and juvenile abundance indexes in Chesapeake Bay to discern any influences of summer habitat suitability on historical changes in populations. Criteria for habitat suitability were those identified in freshwater reservoirs (temperature below 25°C and dissolved oxygen above 2–3 mg/L), which we confirmed for the York-Pamunkey estuary in the lower bay. Habitat suitability in the upper central basin in July declined significantly from 1962 to 1987, as did juvenile abundance indexes (mean catches per standard seine haul). Thickness of suitable temperature-oxygen habitat correlated significantly with Maryland juvenile indexes the following year. Relative reproductive performance of upper (Maryland) and lower (Virginia) bay stocks changed between 1967–1973 and 1980–1988 in parallel with reduction in upper bay summer habitat. The annual temperature-oxygen cycle in the bay revealed two key areas for striped bass subadults and adults: (1) a zone of cool water in north-central Chesapeake Bay near Annapolis, Maryland, where fish of these ages congregate in summer, and (2) a shallow sill across the lower bay near the mouth of the Rappahannock River, Virginia, where warm surface waters (>25°C) in summer impinge on the bottom and may block egress from the bay. The importance of year-round bay residents for reproduction in the upper bay may have been underestimated previously, at least for the recent low population levels. Reduced juvenile production at the head of the bay and population decline would be consistent with limitation of historically important habitat in summer and resultant physiological stresses of high temperature and low dissolved oxygen that affect reproductive competence the following year.
Striped bass Morone saxatilis has a paradoxical record of distribution and abundance, including population declines in coastal waters and variable success of freshwater introductions. This record is analyzed for consistency with a hypothesis that striped bass are squeezed between their thermal and dissolved oxygen preferences or requirements. A commonality among diverse field and laboratory observations supports an inherent thermal niche for the species that changes to lower temperatures as fish age. This shift can cause local conditions, especially warm surface strata and deoxygenated deep water, to be incompatible with the success of large fish. Crowding due to temperature preferences alone or coupled with avoidance of low oxygen concentrations can lead to pathology and overfishing, which may contribute to population declines. Through a mixture of evidence and conjecture, the thermal niche-dissolved oxygen hypothesis is proposed as a unified perspective of the habitat requirements of the species that can aid in its study and management. 139 references, 12 figures.
Subadult striped bass, Morone saxatilis, tagged with temperature-sensing ultrasonic transmitters in April-October and monitored in freshwater lakes generally occupied waters of 20 to 24°C, when these temperatures were available. When they were not (spring and fall), fish occupied nearly the warmest water available at depths > 1.5 m. Excursions of less than 2 minutes duration to warmer and to cooler water than was generally occupied were common in spring and summer. A thermal niche for subadult striped bass of 20 to 24°C centering near 22°C, as suggested by these results, would have important implications for managing this species in fresh water.
Striped bass (Morone saxatilis) in the Apalachicola River, Florida, were tagged from 1978 to 1982 to estimate population size, measure growth, monitor movement, and determine the exploitation rate. Native Gulf Coast striped bass (STB-G) and introduced striped bass from the Atlantic Ocean (STB-A) have occurred together in the Apalachicola River system since 1966 when STB-A were first stocked. Growth of both races was similar and comparable to growth in other waters. In 1981, the population estimate for all striped bass more than 381 mm long in the upper Apalachicola River was 1,500-2,000 fish, of which 43% were STB-G, 51% STB-A, and 6% intermediates. STB-G larger than 600 mm SL had statistically significant (P = 0.05) higher yearly average condition factors. Average percent weight loss during the summer was less (9.4 vs. 15%) in STB-G than in the STB-A race striped bass. The population of fish age 7 and older was composed of 29% STB-G and only 8% STB-A. Longevity of STB-G was greater (maximum age 12 vs. 8). Mean length of STB-G and STB-A above 250 mm FL was 587 and 552 mm, respectively. Yearly tag loss was estimated to be 17.7%; exploitation, 22%. Four hundred and twenty-two striped bass were tagged of which 53 were recaptured by anglers and 34 by survey crews. Eight showed a significant amount of movement, with six (3 STB-G, 3 STB-A) traveling upstream through the lock at Jim Woodruff Lock and Dam, and two (STB-A) traveling downriver into the Gulf of Mexico and eastward to the Ochlockonee River, Florida. Most fish (82%) were recaptured in the initial tagging zone. Water temperature greatly influenced striped bass summer habitat selection and survival.
In the NE Gulf of St. Lawrence, in both 1985 and 1986, cod were located most often at temperatures within the range 0-5°C, but when mean densities of their chief prey (capelin Mallotus villosus) were high (>100/105m3) within the coastal zone, cod frequented waters having temperatures similar to those at which this prey were aggregated, within the broader range of temperatures -0.5 to 8.5°C. The proportions of cod occupying sea temperature strata were significantly and positively correlated with those of capelin, under two conditions: 1) sea temperatures within the range 1-9°C; and 2) mean capelin densities >100/105m3. Under conditions of lower mean capelin densities, cod distributions were independent of those of capelin. -from Authors
We investigated the predator-prey interactions of two pelagic species, landlocked Atlantic salmon Salmo salar and rainbow smelt Osmerus mordax, in a large-lake ecosystem. Our goal was to determine the overlap of habitats selected, based on profiles of temperature and dissolved oxygen (DO). We used hydroacoustics to ascertain the seasonal habitat selection of rainbow smelt and gill nets to sample Atlantic salmon in the Inland Sea of Lake Champlain, Vermont. We identified patterns of smelt habitat selection by overlaying the acoustically determined vertical distributions of smelt onto profiles of water temperature and DO. To verify species composition of acoustical targets, we performed midwater trawls using a stepped-oblique method and found that rainbow smelt constituted 99.5% of trawl catches. Trawl catches and acoustic fish density were correlated, indicating that acoustic targets represented trawled fish. Atlantic salmon habitat selection was estimated from temperature and DO profiles taken at gill nets that caught salmon. Data for Atlantic salmon and rainbow smelt demonstrated extensive spatial overlap in habitat selection during the three sampling seasons. Our results provide greater insight into the predator-prey interactions of these species as mediated by environmental factors. Because Atlantic salmon are stocked, this insight into the predator-prey interactions may assist managers in effectively regulating stocking numbers.
Behavior of adult striped bass Morone saxatilis in the Flint River-Lake Seminole portion of the Apalachicola River system was evaluated to determine if temperature preferences differed from those of striped bass from Atlantic coast stocks. Previous research has shown that striped bass native to this Gulf of Mexico river system had higher condition factors, greater longevity, and less weight loss in summer than did introduced Atlantic fish, presumably because the native fish were better adapted to the higher temperatures prevalent in waters of the Gulf region. Radiotelemetry was used to monitor fish distribution and temperature selection from March 1984 to November 1985. Seasonal distribution patterns and influences of water temperature on striped bass behavior were similar to those reported elsewhere for Atlantic striped bass. The fish ranged widely and occurred throughout the 166-km-long study area during fall, winter, and spring. During summer, however, they inhabited spring-fed areas almost exclusively. The fish moved into these sites during May, when surrounding waters averaged 24.3°C, and remained there through late October or early November, when ambient water temperatures declined to an average of 20.1°C. Temperatures selected by the fish averaged 21.6°C during both summers. When the data were separated into subsets of native Gulf and introduced Atlantic striped bass by the use of previously reported meristic characteristics, there were no differences between groups for average temperatures selected during summer or for temperatures at which the fish moved into or out of springs. The results indicate that preferred temperatures of striped bass in the Apalachicola River are not higher than those of other stocks.
Thermal habitat was recorded by data storage tags (DSTs) applied to Atlantic salmon (Salmo salar L.) kelts during their seaward migration in the spring of 1998 at enumeration facilities in Highlands River, Humber River, Western Arm Brook, and Campbellton River, Newfoundland. In total, 139 DSTs were applied and data were downloaded from eleven of the recovered tags. The recovered tags had been applied at Highlands, Campbellton and Western Arm rivers and recovered in the coastal waters of Newfoundland and Québec and at the enumeration facilities at Highlands and Campbellton rivers. Water temperatures experienced by the fish were recorded for periods of 62–118 days at resolutions of 15–30 min. The data from the sea record on the DSTs were analysed for temperature patterns in relation to migration behaviour and diurnal movement of the fish. A variety of patterns were exhibited on the temperature records suggesting that the fish were behaving in various ways at different times. For Campbellton and Highlands fish over the course of some 24 h periods, night-time temperatures changed little and were among the highest daily temperatures experienced by the fish, whereas daytime temperatures often showed dramatic and frequent shifts in temperature presumably as the fish rapidly and frequently changed depth. For the Western Arm Brook fish, rapid fluctuations in temperature occurred sometimes during the day and night without a consistent diurnal pattern. We also considered large-scale aspects of the data by examining oceanographic conditions in relation to the temperatures recorded by the tags.
Eleven Arctic charr (Salvelinus alpinus) (370–512 mm) and eight sea trout (Salmo trutta) (370–585 mm in length) were tagged externally or internally with depth- and temperature-measuring data-storage tags (DST) before they were released into the sea in the Alta Fjord in north Norway in June 2002. All sea trout were recaptured after they spent 1–40 days at sea, while all Arctic charr were recaptured after 0.5–33 days at sea. On average, trout preferred water about 0.6 m deeper and 1.3°C warmer than Arctic charr. Arctic charr spent >50% of their time between 0 and 1 m depth, while trout spent >50% of their time between 1 and 2 m depth. Both species spent >90% of their time in water no deeper than 3 m from the water surface. However, sea trout dove more frequently and to greater depths (max. 28 m) than Arctic charr (max. 16 m), and these deep dives were most frequently performed at the end of the sea migration. Arctic charr demonstrated a diel diving pattern, staying on average about 0.5 m deeper between 08:00 hours and about 15:00 hours than during the rest of the 24 h, even though there was continuous daylight during the experiments. When comparing data obtained from the DSTs with temperature measurements within the fjord system, the two species were observed to select different feeding areas during their sea migration, the sea trout choosing the inner and warmer parts of the fjord, in contrast to the Arctic charr that preferred the outer, colder parts of the fjord. The observed differences in migration behaviour between the two species are discussed in relation to species preferences for prey and habitat selection, and their optimal temperatures for growth.
We present a new technique for isolating climate signals in time series with a characteristic red noise background which arises from temporal persistence. This background is estimated by a robust procedure that, unlike conventional techniques, is largely unbiased by the presence of signals immersed in the noise. Making use of multiple-taper spectral analysis methods, the technique further provides for a distinction between purely harmonic (periodic) signals, and broader-band (quasiperiodic) signals. The effectiveness of our signal detection procedure is demonstrated with synthetic examples that simulate a variety of possible periodic and quasiperiodic signals immersed in red noise. We apply our methodology to historical climate and paleoclimate time series examples. Analysis of a 3 million year sediment core reveals significant periodic components at known astronomical forcing periodicities and a significant quasiperiodic 100 year peak. Analysis of a roughly 1500 year tree-ring reconstruction of Scandinavian summer temperatures suggests significant quasiperiodic signals on a near-century timescale, an interdecadal 16–18 year timescale, within the interannual El Nio/Southern Oscillation (ENSO) band, and on a quasibiennial timescale. Analysis of the 144 year record of Great Salt Lake monthly volume change reveals a significant broad band of significant interdecadal variability, ENSO-timescale peaks, an annual cycle and its harmonics. Focusing in detail on the historical estimated global-average surface temperature record, we find a highly significant secular trend relative to the estimated red noise background, and weakly significant quasiperiodic signals within the ENSO band. Decadal and quasibiennial signals are marginally significant in this series.
Charges of behavioral and sex-role stereotyping in preschool picture books have led to the publication of books that purportedly avoid or challenge traditional sex stereotypes (i.e., positive image or nonsexist picture books). This study sought to identify behaviors (as distinguished from sex-typed activities or social roles) exhibited by female and male characters in nonsexist books, and to compare these portrayals with those presented in more conventional picture books (Caldecott award-winners and contemporary best-sellers). A reliable coding system (interrater reliability exceeding 90%), permitting the identification of 15 target behaviors in the text and illustrations of picture books was developed and employed in the content analysis of 50 nonsexist and 46 conventional picture books. Stepwise discriminant function and chi-square analyses revealed highly independent females and nurturant and nonaggressive males in nonsexist books—portrayals that represent a clear departure from traditional sex stereotypes in this society. On the other hand, females in nonsexist books were more nurturant, emotional, and less physically active than males in either nonsexist or conventional books. Finally, with the single exception of aggressive behavior (males exceeding females), there was no indication of behavioral sex-typing in the conventional books. Implications are discussed.
Herbivore damage is generally detrimental to plant fitness, and the evolu- tionary response of plant populations to damage can involve either increased resistance or increased tolerance. While characters that contribute to resistance, such as secondary chem- icals and trichomes, are relatively well understood, characters that contribute to a plant's ability to tolerate damage have received much less attention. Using Helianthus annuus (wild sunflower) and simulated damage of Haplorhynchites aeneus (head-clipping weevil) as a model system, we examined morphological characters and developmental processes that contribute to compensatory ability. We performed a factorial experiment that included three levels of damage (none, the first two, or the first four inflorescences were clipped with scissors) and eight sires each mated to four dams. We found that plants compensated fully for simulated head-clipper damage and that there was no variation among plant families in compensatory ability: seed production and mean seed mass did not vary among treat- ments, and sire X treatment interactions were not significant. Plants used four mechanisms to compensate for damage: (1) Clipped plants produced significantly more inflorescences than unclipped plants. Plants produced these additional inflorescences on higher order branches at the end of the flowering season. (2) Clipped plants filled significantly more seeds in their remaining heads than did unclipped plants. (3) Clipped plants, because they effectively flowered later than unclipped plants, were less susceptible to damage by seed- feeding herbivores other than Haplorhynchites. (4) In later heads, seed size was greater on clipped plants, which allowed mean seed size to be maintained in clipped plants. Although there was genetic variation among the families used in this experiment for most of the characters associated with compensation for damage (seed number, mean seed size, mean flowering date, length of the flowering period, and branching morphology), in analyses of these characters, no sire X treatment interactions were significant indicating that all of the families relied on similar mechanisms to compensate for damage.
Linear Mixed-Effects * Theory and Computational Methods for LME Models * Structure of Grouped Data * Fitting LME Models * Extending the Basic LME Model * Nonlinear Mixed-Effects * Theory and Computational Methods for NLME Models * Fitting NLME Models
Western Cape Cod Bay: hydrographic, geo-logical, ecological and meteorological backgrounds for environmental studies In: Observations on the Ecology and Biology of Western Cape Cod Bay, Massachusetts
- J D Davis
Davis, J.D. (1984) Western Cape Cod Bay: hydrographic, geo-logical, ecological and meteorological backgrounds for environmental studies. In: Observations on the Ecology and Biology of Western Cape Cod Bay, Massachusetts. J.D. Davis & D. Merriman (eds) Lecture Notes on Coastal and Estuarine Studies 11: Springer-Verlag, pp. 1–18.
Physical Oceanographic Investigation of Massachusetts and Cape Cod Bays
- W Geyer
- G B Gardner
- W Brown
Geyer, W., Gardner, G.B., Brown, W. et al. (1992) Physical
Oceanographic Investigation of Massachusetts and Cape Cod
Bays, Technical Report MBP-92-03, Massachusetts Bays Program. Boston, Massachusetts: U.S. EPA Region I ⁄ Massachusetts Coastal Zone Management Office, pp. 497.
A study of the marine resources of Salem Sound
- B C Chase
- J Plough
- W Castonguay
Chase, B.C., Plough, J. and Castonguay, W. (2002) A study of the marine resources of Salem Sound, 1997. Mass. Div. Mar. Fish. Tech. Rep. TR-6: 143.
Ecological Methodology
- C J Krebs
Krebs, C.J. (1989). Ecological Methodology New York: Harper and Row, pp. 654.
R: a Language and Environment for Statistical Computing Vienna: R Foundation for Statistical Computing
- R Development
- Core Team
R Development Core Team (2008) R: a Language and Environment for Statistical Computing. Vienna: R Foundation for
Statistical Computing. ISBN 3-900051-07-0, URL http://
www.R-project.org.
- Geyer
A study of the marine resources of Salem Sound, 1997
- Chase B.C.
- Davis