Articles

Published journal articles by MLML faculty, staff and students. Full text is included when copyright allows.


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The relationship between water motion and living rhodolith beds in the southwestern Gulf of California, Mexico
The relationship between water motion and living rhodolith beds in the southwestern Gulf of California, Mexico
Free living, nodular aggregates of non-geniculate coralline algae (rhodoliths) have occurred since the Cenozoic in diverse marine environments around the world. Fossil rhodolith morphology and distribution have been widely used as paleoecological indicators, particularly of water motion. However, few studies have verified these relationships in living beds. The relationship between water motion and rhodolith movement was examined in three subtidal rhodolith beds off the southwestern coast of the Gulf of California, one dominated by wave action and two dominated by tidal currents. Field experiments and simultaneous video and current measurements taken during winter 1996 showed that rhodoliths in the shallow margins (4.5 m depths) of wave-dominated beds moved frequently due to threshold-level velocities from wind-propagated waves. Rhodoliths did not move in the middle and at deep margins of the bed due to attenuation of wave energy. Historical wind records and waveforcasting analysis indicate that shallow rhodolith movement is frequent only in the winter. In deep tidally dominated beds, maximum yearly tidal currents were not sufficient to move rhodoliths. Video and SCUBA surveys showed that bioturbation is an important mechanism for rhodolith movement in all beds. Rhodoliths in 12-m-deep tidally dominated beds and in the deep margins of wave-dominated beds appear to move only occasionally due to bioturbation and severe storms. Results imply that rhodolith morphology and distribution are dependent on a combination of factors. These factors, especially bioturbation, should be considered when using rhodoliths as paleoecological indicators., Cited By (since 1996):66
The relationship between δ13C of organic matter and [CO2(aq)] in ocean surface water: Data from a JGOFS site in the northeast Atlantic Ocean and a model
The relationship between δ13C of organic matter and [CO2(aq)] in ocean surface water: Data from a JGOFS site in the northeast Atlantic Ocean and a model
The δ13C of suspended particulate organic matter (SPOM) in surface waters increased from -22.9 to -18.1‰ during April 25-May 31, 1989 at the JGOFS North Atlantic Bloom Experiment Site (NABE Site; 47°N, 20°W). During the same period, nearly parallel increases in sinking POM δ13C were also found, although these values were usually lower than those of the corresponding SPOM. Consistent with the hypothesis that plankton δ13C and [CO2(aq)] are inversely related, the increases in both sinking and suspended POM δ13C were highly negatively correlated with mixed-layer [CO2(aq)] that generally decreased from 10.1-13.2 μmoles/kg during the five weeks. The change in SPOM δ13C per change in [CO2(aq)], however, appears to be somewhat greater than that expected from previous, though less direct, ocean and laboratory evidence. By adapting a model of plant δ13C by Farquhar et al. (1982), it is shown that under a constant phytoplankton demand for CO2 an inverse, nonlinear SPOM δ13C response to ambient [CO2(aq)] is expected. Such trends are unlike the negative linear relationships indicated by data from the NABE Site and or from Southern Hemisphere waters. Such differences between predicted and observed SPOM δ13C vs. [CO2(aq)] trends and among observed relationships can be reconciled, however, if biological CO2 demand is allowed to vary. This has significant implications for the use of the δ13C of plankton (or their organic subfractions or sedimentary remains) as a proxy for past or present ocean CO2 concentrations and biological productivity. © 1992., Cited By (since 1996):148, Oceanography
The response of Monterey Bay to the 2010 Chilean earthquake
The response of Monterey Bay to the 2010 Chilean earthquake
The primary frequencies contained in the arrival sequence produced by the tsunami from the Chilean earthquake of 2010 in Monterey Bay were extracted to determine the seiche modes that were produced. Singular Spectrum Analysis (SSA) and Ensemble Empirical Mode Decomposition (EEMD) were employed to extract the primary frequencies of interest. The wave train from the Chilean tsunami lasted for at least four days due to multipath arrivals that may not have included reflections from outside the bay but most likely did include secondary undulations, and energy trapping in the form of edge waves, inside the bay. The SSA decomposition resolved oscillations with periods of 52-57, 34-35, 26-27, and 21-22 minutes, all frequencies that have been predicted and/or observed in previous studies. The EEMD decomposition detected oscillations with periods of 50-55 and 21-22 minutes. Periods in the range of 50-57 minutes varied due to measurement uncertainties but almost certainly correspond to the first longitudinal mode of oscillation for Monterey Bay, periods of 34-35 minutes correspond to the first transverse mode of oscillation that assumes a nodal line across the entrance of the bay, a period of 26- 27 minutes, although previously observed, may not represent a fundamental oscillation, and a period of 21-22 minutes has been predicted and observed previously. A period of ~37 minutes, close to the period of 34-35 minutes, was generated by the Great Alaskan Earthquake of 1964 in Monterey Bay and most likely represents the same mode of oscillation. The tsunamis associated with the Great Alaskan Earthquake and the Chilean Earthquake both entered Monterey Bay but initially arrived outside the bay from opposite directions. Unlike the Great Alaskan Earthquake, however, which excited only one resonant mode inside the bay, the Chilean Earthquake excited several modes suggesting that the asymmetric shape of the entrance to Monterey Bay was an important factor and that the directions of the incoming tsunami-generated waves were most likely different. The results from SSA and EEMD produced results that differed. Although a period of 34-35 minutes was observed in the SSA, it was not detected in the EEMD. In previous comparisons, however, we have observed that oscillations detected in EEMD were not detected in SSA. SSA also revealed an oscillation with a period of 26-27 minutes, not observed in the EEMD. This oscillation, however, may not represent a fundamental mode but instead a harmonic related to the first longitudinal mode of oscillation whose period is ~55 minutes. We conclude that both methods were useful in helping to interpret the results of this study., Cited By (since 1996):2, Oceanography
The response of Monterey bay to the great Tohoku earthquake of 2011
The response of Monterey bay to the great Tohoku earthquake of 2011
Cited By (since 1996):1, Export Date: 28 April 2014
The role of alternate life-history stages of a marine macroalga: A seed bank analogue?
The role of alternate life-history stages of a marine macroalga: A seed bank analogue?
Many organisms occurring in temporally variable environments have evolved life-history traits that enable their populations to persist during unfavorable environmental conditions. Numerous terrestrial plants, insects, and marine invertebrates, for example, rely on resting stages that disperse their propagules in time. Although widely observed among many taxa, few examples exist for marine macroalgae, at least in part because of the methodology involved in studying them. Here, I determined that microscopic life stages of the annual marine macroalga Desmarestia ligulata overwinter during periods when the macroscopic thalli are absent, thereby allowing this species to persist in temporally variable environments. Examination of field-grown microscopic stages with fluorescence microscopy identified these stages as gametophytes. Holdfast tagging experiments determined that recruitment of the macroscopic stages was not enhanced by regrowth of perennial thalli as observed in other macroalgae, suggesting that overwintering gametophytes were the sole source of sporophyte recruitment. In contrast to true resting stages, Desmarestia gametophytes were not dormant, but rather were metabolically active, sensitive to small differences in environmental quality, and highly subject to physical damage. Gametophyte photosynthetic rates were greater under higher irradiance, and growth rates were greater under longer photoperiods and higher irradiance. Although their survival appeared to be reduced by grazing from large (>1 cm) invertebrates and sedimentation, gametophytes were able to survive in the field for at least 15 mo and thereby enhance sporophyte recruitment more than a year after settlement. I suggest that Desmarestia gametophytes be regarded as alternate life-history stages that simply maintain populations under a different set of environmental conditions than the macroscopic sporophytes do, rather than as 'dormant' or 'resting' stages., Cited By (since 1996):25, Seaweeds, CODEN: ECOLA
The role of body size in individual-based foraging strategies of a top marine predator
The role of body size in individual-based foraging strategies of a top marine predator
Body size is an important determinant of the diving and foraging ability in airbreathing marine vertebrate predators. Satellite-linked dive recorders were used during 20032004 to investigate the foraging behavior of 22 male California sea lions (Zalophus californianus, a large, sexually dimorphic otariid) and to evaluate the extent to which body size explained variation among individuals and foraging strategies. Multivariate analyses were used to reduce the number of behavioral variables used to characterize foraging strategies (principal component analysis, PCA), to identify individually based foraging strategies in multidimensional space (hierarchical cluster analysis), and to classify each individual into a cluster or foraging strategy (discriminant analysis). Approximately 81.1% of the variation in diving behavior among individuals was explained by three factors: diving patterns (PC1), foraging effort (PC2), and behavior at the surface (PC3). Individuals were classified into three distinct groups based on their diving behavior (shallow, mixed depth, and deeper divers), and jackknife resampling of the data resulted in correct group assignment 86% of the time. Body size as an independent variable was positively related to dive duration and time spent ashore and negatively related to time at sea, and it was a key parameter in PC2 used to classify the three distinct clusters. Differences among individual-based foraging strategies probably were driven by differences in body size, which enabled larger animals to dive deeper and forage more efficiently by targeting different and perhaps larger prey items. The occurrence of foraging specializations within a species and age class has implications for quantitative modeling of population-level predator-prey interactions and ecosystem structure. © 2010 by the Ecological Society of America., Cited By (since 1996):17, Marine Mammals, Birds & Turtles, CODEN: ECOLA
The role of internal tides in the nutrient enrichment of Monterey Bay, California
The role of internal tides in the nutrient enrichment of Monterey Bay, California
Semidiurnal internal tides in Monterey Canyon are shown to be partially responsible for macronutrient enrichment of surface waters in Monterey Bay, California. CTD time series at five stations in the canyon revealed the presence of semidiurnal internal tides with heights between 50 and 120 m. p Thermistor data demonstrated an internal tidal bore at the head of the canyon. Data and theory suggest that internal tidal bores may be breaking, due to either shear instability or direct overturning, thereby enriching the immediate area near the canyon head. Transects normal to Monterey Canyon showed a 20-m thick lens of 12 °C water moving out of the canyon at high internal tide. This lens was then pinched off from the canyon, and led to a density-induced divergence. The nutrient transport associated with the internal tidal divergence could support as much as 30% of the daily primary productivity in the northern part of Monterey Bay during non-upwelling periods. © 1982., Cited By (since 1996):29, Oceanography, CODEN: ECSSD
The seasonal importance of small coastal sharks and rays in the artisanal elasmobranch fishery of Sinaloa, Mexico
The seasonal importance of small coastal sharks and rays in the artisanal elasmobranch fishery of Sinaloa, Mexico
Seasonal surveys were conducted during 1998-1999 in Sinaloa, Mexico to determine the extent and activities of the artisanal elasmobranch fishery operating in the southeastern Gulf of California. Twenty-eight fishing sites were documented, the majority of which (78.6%) targeted elasmobranchs during some part of the year. Sharks numerically dominated sampled landings (65.0%, n = 2390), and catch rates exceeded those of rays during autumn-spring. The scalloped hammerhead, Sphyrna lewini, was the primary fishery target during these seasons, with most landings composed of early life stages. During summer, rays, especially Rhinoptera steindachneri, were numerically dominant (87.7%). Large sharks were of comparably minor importance in the artisanal fishery during all seasons. Catch composition was similar between spring and winter (SIMobs = 0.393, SIMexp = 0.415; P = 0.25), largely because the fishery mainly targeted "cazón" (sharks < 1.5 m total length) during this period (e.g., S. lewini, Rhizoprionodon longurio). Small size classes of large sharks and a wide size range of coastal sharks and rays were primarily observed. In addition, size composition of S. lewini and to a lesser extent, R. longurio decreased significantly between historic and contemporary landings. Local populations of these species should therefore be closely monitored., Cited By (since 1996):2, Fish and Fisheries, Source: Scopus
The state of the California Current, 2005-2006: Warm in the north, cool in the south
The state of the California Current, 2005-2006: Warm in the north, cool in the south
This report summarizes the recent state of the California Current System (CCS), primarily during the period April 2005 through early 2006, and includes observations of ocean conditions made from Washington State south to Baja California. During 2005, the CCS experienced very unusual "ocean weather." For example, off Washington, Oregon and northern California, the start of upwelling was delayed, resulting in anomalously warm sea surface temperatures through the spring and the early summer months. The warming observed in the northern California Current (NCC) in the spring and early summer appeared to be a regional phenomenon, since waters south of approximately 35°N to the California-Mexico border were near the long-term average, and cooler-than-normal temperatures prevailed off Baja California. The extent of the warming and subsequent ecosystem response was similar to that of a major tropical El Niño event. However, we know from observations made at the equator that equatorial waters were in an El Niño-neutral state. The impacts on the NCC pelagic ecosystem were profound with very low biomass of Zooplankton observed in Monterey Bay, the Gulf of the Farallones, and off Oregon, accompanied by unprecedented reproductive failure and mortality in several locally-breeding seabird species. Recruitment failure was seen in a variety of fishes as well. The proximate cause was a delay in the initiation of the upwelling season in the NCC (which usually begins in April) to a nearly unprecedented start time of late July. Thus, animals that reproduce in spring and in other years would find bountiful food resources, found themselves faced with famine rather than feast. Similarly, marine mammals and birds which migrate to the NCC upwelling region in spring and summer, which would otherwise find a high biomass of energetically-rich Zooplankton and small pelagic fish upon which to feed, were equally disappointed. Moreover, 2005 marked the third year of chronically warm conditions in the NCC, a situation which could have led to a general reduction in physiological condition of fish and birds, rendering them less tolerant of adverse ocean conditions in 2005., Cited By (since 1996):41, Ecology
The state of the California current, 2006-2007: Regional and local processes dominate
The state of the California current, 2006-2007: Regional and local processes dominate
The state of the California Current System (CCS) between Oregon and Baja California is summarized in this report, covering spring 2006 to spring 2007. Observations reported here are based on contributions from various ocean observing programs along the West Coast of North America. Basin-scale indicators were variable or neutral over the last year. This indeterminate forcing was reflected in conditions in the CCS where no coherent patterns emerged, i.e., no single "state" could be ascribed to the system. Rather, regional or local processes dominated observed patterns. Similar to last year, delayed upwelling off Oregon and central California dramatically affected higher trophic levels: euphausiid recruitment was delayed and as a likely consequence seabird productivity off Central California was extremely depressed. For example, Cassin's auklet had a complete reproductive failure, similar to 2006. Observations during the spring of 2007 demonstrate that these patterns were ephemeral since upwelling was normal and seabird productivity improved. Off southern and Baja California, upwelling-favorable winds were also weak or delayed during 2006, but biological consequences appear to have been relatively minor., Cited By (since 1996):24, Ecology
The structure of Mediterranean rocky reef ecosystems across environmental and human gradients, and conservation implications
The structure of Mediterranean rocky reef ecosystems across environmental and human gradients, and conservation implications
Historical exploitation of the Mediterranean Sea and the absence of rigorous baselines makes it difficult to evaluate the current health of the marine ecosystems and the efficacy of conservation actions at the ecosystem level. Here we establish the first current baseline and gradient of ecosystem structure of nearshore rocky reefs at the Mediterranean scale. We conducted underwater surveys in 14 marine protected areas and 18 open access sites across the Mediterranean, and across a 31-fold range of fish biomass (from 3.8 to 118 g m -2). Our data showed remarkable variation in the structure of rocky reef ecosystems. Multivariate analysis showed three alternative community states: (1) large fish biomass and reefs dominated by non-canopy algae, (2) lower fish biomass but abundant native algal canopies and suspension feeders, and (3) low fish biomass and extensive barrens, with areas covered by turf algae. Our results suggest that the healthiest shallow rocky reef ecosystems in the Mediterranean have both large fish and algal biomass. Protection level and primary production were the only variables significantly correlated to community biomass structure. Fish biomass was significantly larger in well-enforced no-take marine reserves, but there were no significant differences between multi-use marine protected areas (which allow some fishing) and open access areas at the regional scale. The gradients reported here represent a trajectory of degradation that can be used to assess the health of any similar habitat in the Mediterranean, and to evaluate the efficacy of marine protected areas., Cited By (since 1996):21, Art. No.: e32742
The structure of subtidal algal and invertebrate assemblages at the Chatham Islands, New Zealand
The structure of subtidal algal and invertebrate assemblages at the Chatham Islands, New Zealand
We examined the distribution and abundance of organisms on subtidal rocky reefs at nine sites around the Chatham Islands, a remote group 780 km east of southern New Zealand. We sampled five depth strata ranging from 1 to<16 m to identify spatial patterns in the abundance of algae and invertebrates and to assess their variation within and among sites. This information is used to discuss hypotheses concerning community structure at this remote locality. Several patterns were apparent. The immediate subtidal was occupied by the southern bull kelp Durvillaea spp. A suite of 11 fucalean species were dominant to a depth of 10 m with an average abundance of 28 m-2, while one species, Carpophyllum flexuosum, occurred mostly in deeper water. Only two laminarian species of algae were present at the islands. The indigenous Lessonia tholiformis was abundant at 2.5 to 15 m and was not found in deeper water, while the giant kelp Macrocystis pyrifera was abundant at two sites in 12 to 18 m. The commercially valuable abalone Haliotis iris was extremely abundant in shallow water, with an overall mean of 6 m-2 at 5 m. The sea urchin Evechinus chloroticus was common, but reached high densities only in small (<25 m2) patches. The characteristic urchin-dominated zones reported in kelp beds world-wide were not seen. There was considerable site-to-site variation in the occurrence and abundance of individual species. Some differences between sites were associated with shelter from swell (e.g. M. pyrifera was found only in sheltered sites) and physical habitat (e.g. juvenile H. iris were found only beneath boulders inshore), but much of the variation could not be explained by physical or depth-related factors alone. We hypothesize that the differences in these kelp bed assemblages compared to mainland New Zealand are partially due to the high degree of endemism at the Chatham Islands. Local variation cannot be explained by herbivory, and is most likely the result of the various life-history characteristics of the major habitat-forming species, the large brown algae.
The study of feeding habits of two marine fishes in relation to plankton ecology
The study of feeding habits of two marine fishes in relation to plankton ecology
Downloaded from: http://www.jstor.org/stable/3224869 (7 July 2014).
The tail of the Storegga Slide: Insights from the geochemistry and sedimentology of the Norwegian Basin deposits
The tail of the Storegga Slide: Insights from the geochemistry and sedimentology of the Norwegian Basin deposits
Deposits within the floor of the Norwegian Basin were sampled to characterize the deposition from the Storegga Slide, the largest known Holocene-aged continental margin slope failure complex. A 29 to 67 cm thick veneer of variable-coloured, finely layered Holocene sediment caps a homogeneous, extremely well-sorted, poorly consolidated, very fine-grained, grey-coloured sediment section that is >20 m thick on the basin floor. This homogeneous unit is interpreted to represent the uppermost deposits generated by a gravity flow associated with the last major Storegga Slide event. Sediments analogous to the inferred source material of the slide deposits were collected from upslope on the Norwegian Margin. Sediments sampled within the basin are distinguishable from the purported source sediments, suggesting that size sorting has significantly altered this material along its flow path. Moreover, the very fine grain size (3·1 ± 0·3 μm) suggests that the >20 m thick homogeneous unit which was sampled settled from suspension after the turbulent flow was over. Although the turbulent phase of the gravity flow that moved material out into the basin may have been brief (days), significantly more time (years) is required for turbid sediments to settle and dewater and for the new sea floor to be colonized with a normal benthonic fauna. Pore water sulphate concentrations within the uppermost 20 m of the event deposit are higher than those normally found in sea water. Apparently the impact of microbial sulphate reduction over the last ca 8·1 cal ka bp since the re-deposition of these sediments has not been adequate to regenerate a typical sulphate gradient of decreasing concentration with sub-bottom depth. This observation suggests low rates of microbial reactions, which may be attributed to the refractory carbon composition in these re-deposited sediments. © 2010 The Authors. Journal compilation © 2010 International Association of Sedimentologists., Cited By (since 1996):1, Rocks & Cores
The transmission of phocine herpesvirus-1 in rehabilitating and free-ranging Pacific harbor seals (Phoca vitulina) in California
The transmission of phocine herpesvirus-1 in rehabilitating and free-ranging Pacific harbor seals (Phoca vitulina) in California
Phocine herpesvirus-1 (PhHV-1) causes regular outbreaks of disease in neonatal harbor seals (Phoca vitulina) at rehabilitation centers in Europe and in the U.S. To investigate transmission of this virus samples were collected from harbor seal pups during exposure studies at a Californian rehabilitation center from 1999 to 2002 and from free-ranging harbor seals off central California during the same period. The exposure studies provided evidence that PhHV-1 can be transmitted horizontally between animals most likely through direct contact with oro-nasal secretions. However vertical transmission may also occur, as adult female harbor seals were found to be shedding the virus in vaginal and nasal secretions, and premature newborn pups had evidence of early infection. Results also indicated that PhHV-1 infections were common in both free-ranging (40%, 49/121) and rehabilitating (54%, 46/85) young harbor seals, during the spring and early summer. This timing, which correlated with pupping and weaning, suggested that the majority of animals were infected and infective with PhHV-1 between pupping and breeding. © 2004 Elsevier B.V. All rights reserved., Cited By (since 1996):9, Marine Mammals, Birds & Turtles, CODEN: VMICD
The use of geophysical survey data in fisheries management: A case history from southeast Alaska
The use of geophysical survey data in fisheries management: A case history from southeast Alaska
The Alaska Department of Fish and Game (ADF&G) has been conducting a habitat-based stock assessment of yellow-eye rockfish (Sebastes niberrimus) in the eastern Gutf of Alaska since 1989. Yelloweye rockfish occur in rugged rocky terrain on the continental shelf, and are an important commercial species taken in directed, and by-catch bottom-long-line fisheries. The biomass of yelloweye rockfish is derived as the product of density, average weight, and area of habitat. Density is based on line-transect surveys conducted from an occupied submersible. Area estimates of yelloweye habitat are based on the probable distribution of rocky habitat inshore of the 200 m bathymetric contour. Information used to identify rocky habitat include sidescan and multibeam sonar data (ground-truthed using direct observation from the submersible) and commercial logbook data from the directed fishery. In areas with multibeam or sidescan sonar data, the area of rockfish habitat is delineated based on defined substrate types within the mapped area. For areas without these geophysical datasets, position data from commercial fishery logbooks is used. In areas with both logbook and geophysical data, areas of habitat generally overlap but are not identical. Logbook data is mandatory, but self-reported, and may not always be accurate. Geophysical surveys reveal the extent of all rocky habitats, while fishermen target areas of prime habitat. Limiting of surveys to prime habitat may result in inaccurate stock assessments because density may remain stable in the prime habitat, while declining in surrounding habitats. By assessing fish densities in all rockfish habitats, as delineated by geophysical surveys, a better indicator of stock condition is possible. Further unlike logbook data, multibeam data allows us to clearly define boundaries of prime habitats, relevant to management decisions regarding marine reserves or to definition of management units.
The use of substratum manipulations in field studies of seaweed colonization and growth
The use of substratum manipulations in field studies of seaweed colonization and growth
Natural and artificial surfaces have been used to investigate marine fouling, succession, and pollution; for experiments on factors affecting the insitu colonization and growth of seaweeds; and for growing large quantities of commerically important species. The use of field clearings and artificial substrata, and their advantages and disadvantages in small-scale studies and commercial production are discussed. Substratum toxicity, color, roughness, large-scale heterogeniety, and water-holding capacity may affect settlement and growth, and must be considered when using artificial materials. Plates, ropes, and other substrata require support structures and may not precisely simulate cleared natural areas, but have the advantages of easy manipulation and sampling, and are the only means available for studying spores and other small stages in the field. Growing seaweeds can be an effective alternative to transplanting adults. If properly designed and placed, these substrata could be incorporated into artificial polyculture reefs.
The validity of using morphological characteristics as predictors of age in the kelp, Pterygophora californica (Laminariales, Phaeophyta)
The validity of using morphological characteristics as predictors of age in the kelp, Pterygophora californica (Laminariales, Phaeophyta)
Previous studies have used stipe ring counts to estimate the age of several species in the Laminariales. Although this method is widely accepted, it has rarely been validated. To test the validity of aging Pterygophora californica by counting rings formed in the stipe, we sampled plants of known age between 1.0 and 4.4 yr old and plants with a calculated age of 12 yr. For a given cohort, the number of complete rings closely approximated the known age in years. indicating ring counts are a reliable method for estimating the age structure of P califomica populations. However, ring counts from individual plants of known age can vary by ± 2 yr (95 % CI), and among readers counting the same plants by ± 1 yr (95 % CI). Single plants, there fore, could not be reliably aged by ring counts Linear relationships between 2 morphometric measures (stipe length and stipe diameter) and number of rings varied both within and between stands and sites, suggesting these measures are not reliable for estimating the age of this alga in the areas sampled. Stand density may be an important factor contributing to the variation in these morphome tric measures. Short-term (22 wk) field manipulations of stand density showed that plants at high density (30 plants m^-2) grew faster in stipe length and slower in stipe diameter than those at medium (6 plants m^-2) and low (2 plants m^-2) densities. Plants collected in a multi-site survey, however, showed no relationship between stand density and stipe morphology, indicating factors other than density also influence stipe growth Short-term (22 wk) field manipulations, which reduced ambient light levels by up to 58 %. had no significant effects on stipe morphology.
The vertical distribution  and feeding habits of two common midwater fishes (Leuroglossus stilbius and Stenobrachius leucopsarus) off Santa Barbara
The vertical distribution and feeding habits of two common midwater fishes (Leuroglossus stilbius and Stenobrachius leucopsarus) off Santa Barbara
Downloaded from: calcofi.org/publications/calcofireports/.../Vol_31_Cailliet___Ebeling.pdf (9 July 2014).
Thermal stratification drives movement of a coastal apex predator
Thermal stratification drives movement of a coastal apex predator
A characterization of the thermal ecology of fishes is needed to better understand changes in ecosystems and species distributions arising from global warming. The movement of wild animals during changing environmental conditions provides essential information to help predict the future thermal response of large marine predators. We used acoustic telemetry to monitor the vertical movement activity of the common dentex (Dentex dentex), a Mediterranean coastal predator, in relation to the oscillations of the seasonal thermocline during two summer periods in the Medes Islands marine reserve (NW Mediterranean Sea). During the summer stratification period, the common dentex presented a clear preference for the warm suprathermoclinal layer, and adjusted their vertical movements following the depth changes of the thermocline. The same preference was also observed during the night, when fish were less active. Due to this behaviour, we hypothesize that inter-annual thermal oscillations and the predicted lengthening of summer conditions will have a significant positive impact on the metabolic efficiency, activity levels, and population dynamics of this species, particularly in its northern limit of distribution. These changes in the dynamics of an ecosystem's keystone predator might cascade down to lower trophic levels, potentially re-defining the coastal fish communities of the future. © 2017 The Author(s).
Three decades of sea water abstraction by Kapar power plant (Malaysia)
Three decades of sea water abstraction by Kapar power plant (Malaysia)
Zooplankton samples collected before (1985–86) and after (2013–14) the establishment of Kapar power station (KPS) were examined to test the hypothesis that increased sea surface temperature (SST) and other water quality changes have altered the zooplankton community structure. Elevated SST and reduced pH were detected between before and after impact pairs, with the greatest impact at the station closest to KPS. Present PAHs and heavy metal concentrations are unlikely causal factors. Water parameter changes did not affect diversity but community structure of the zooplankton. Tolerant small crustaceans, salps and larvaceans likely benefited from elevated temperature, reduced pH and shift to a more significant microbial loop exacerbated by eutrophication, while large crustaceans were more vulnerable to such changes. It is predicted that any further rise in SST will remove more large-bodied crustacean zooplankton, the preferred food for fish larvae and other meroplankton, with grave consequences to fishery production.
Tidal and nontidal oscillations in Elkhorn Slough, CA
Tidal and nontidal oscillations in Elkhorn Slough, CA
Elkhorn Slough is a shallow, tidally forced estuary that is directly connected to Monterey Bay. It is ebb-dominated and, due to continued erosion, the tidal prism has tripled over the past 40 years. Water level measurements at four locations are used to examine tidal and nontidal oscillations in Elkhorn Slough. The tidal response of Elkhorn Slough differs from that of Monterey Bay primarily due to the generation of a relatively large number of shallow-water tidal constituents that are due to tidal distortion caused by friction along the bottom and lateral boundaries, intertidal storage, and nonlinear advection. The shallow-water constituents range from 3 to almost 15 cycles per day (cpd) and include a rich variety of overtides and compound tides, whose amplitudes generally increase toward the head of the slough. The tidal harmonics are seasonally dependent, with lower amplitudes during the fall and winter and higher amplitudes in summer. The tidal constituents were examined using two types of spectral decomposition, the conventional power spectrum and the more recent Hilbert spectrum. Unlike the power spectrum, the Hilbert spectrum does not reveal any harmonic structure in the data. Energy associated with tidal distortion in this case appears to be broadly distributed across the spectral continuum. At least four nontidal oscillations occur in Elkhorn Slough with frequencies of 26.0, 39.7, 52.7, and 66.9 cpd. The Hilbert spectrum reveals maxima at 26, 39.7, and 66.9 cpd, but not at 52.7 cpd, suggesting that it is harmonically related to the oscillation at 26.0 cpd. The nontidal oscillations fall into the range of frequencies associated with the natural oscillations of Monterey Bay. However, evolutionary power spectra indicate that they appear to be permanent features of the system and thus are not necessarily consistent with seiche-like oscillations that are often transient and subject to damping. These oscillations could be caused by several factors including edge waves along the coast of Monterey Bay, long-period surface waves of atmospheric origin that enter the bay from offshore, or breaking internal waves in and around the Monterey Submarine Canyon. In conclusion, detailed hydrodynamic models are needed to provide a better understanding of how tidal harmonics are generated and preserved in Elkhorn Slough, and to determine the origin of the natural oscillations in Monterey Bay. © 2007 Coastal and Estuarine Research Federation., Cited By (since 1996):12
Tidal movements of East Pacific green turtle Chelonia mydas at a foraging area in Baja California Sur, México
Tidal movements of East Pacific green turtle Chelonia mydas at a foraging area in Baja California Sur, México
We tracked East Pacific green turtles Chelonia mydas using GPS-VHF telemetry in Estero Banderitas, a tidally-influenced foraging area in Bahía Magdalena, Baja California Sur, México. Tidal currents were measured with a bottom-mounted Acoustic Doppler Profiler (ADP) and the data used to predict tidal current speed and direction at the location and time during which turtles were tracked. Twenty-nine turtles were tracked in the summers of 2000 to 2003. Vagility (mean ± SD; 18.6 ± 11.4 km d-1) and speed (0.83 ± 0.47 km h-1) of turtles was the greatest so far reported for green turtles at foraging areas. Turtles displayed highly linear movements, and movement patterns were circatidal. Vector correlation was used to compare turtle speed and direction with tidal speed and direction. Correlation coefficients were significant for 11 out of 13 tracks, indicating significant linear interdependence between turtles and tides. Speed and direction contributed equally to the correlation. Results indicated a new paradigm for green turtles in feeding areas, where turtles are transported on continual tides that allow them to exploit a patchy and seasonal distribution of algae, their main diet component. This tidal transport is markedly different than Selective Tidal Stream Transport, in which animals use either the ebb or flood tide for transport. Tidal currents may be an accurate indicator of turtle movement in tidal areas, and this transport system has implications for foraging ecology, energetics, and growth. © Inter-Research 2009., Cited By (since 1996):8, Marine Mammals, Birds & Turtles, CODEN: MESED
Tidal movements of female leopard sharks (Triakis semifasciata) in Elkhorn Slough, California
Tidal movements of female leopard sharks (Triakis semifasciata) in Elkhorn Slough, California
The leopard shark (Triakis semifasciata) is one of the most common species of elasmobranch in California, and uses the shallow bays and estuaries of California extensively throughout its life history. To examine the role that tides and time of day play on the distribution and movements of leopard sharks in an estuarine environment, a total of 22 female leopard sharks (78-140 cm TL) were tagged with acoustic transmitters in Elkhorn Slough, California, USA. Eight sharks were manually tracked for 20-71. 5 h, and 13 sharks were monitored for 4-280 days using an array of acoustic receivers. Overall, the distribution and movements of sharks were strongly influenced by the tides and to a lesser extent by period of day, although general patterns of movement differed depending on what region of Elkhorn Slough the sharks were using. In the main channel of Elkhorn Slough, sharks generally moved with the tide, maximizing the area over which they could forage on a more dispersed prey field. Conversely, leopard sharks within the Elkhorn Slough National Estuarine Research Reserve regularly swam against strong currents to remain in proximity to the intertidal mudflats. This high degree of fidelity to a specific region was probably due to an abundance of important prey in the area. These results indicate that movements, and thus the foraging ecology, of leopard sharks show a high degree of plasticity and are influenced by tidal stage, tidal current, availability of suitable habitat, and availability and distribution of important prey items. © 2010 Springer Science+Business Media B.V., Cited By (since 1996):2, Fish and Fisheries, CODEN: EBFID

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