Predicting population consequences of ocean climate change for an ecosystem sentinel,the seabird Cassin's auklet

Forecasting the ecological effects of climate change on marine species is critical for informing greenhouse gas mitigation targets and developing marine conservation strategies that remain effective and increase species' resilience under changing climate conditions. Highly productive coastal upwelling systems are predicted to experience substantial effects from climate change, making them priorities for ecological forecasting. We used a population modeling approach to examine the consequences of ocean climate change in the California Current upwelling ecosystem on the population growth rate of the planktivorous seabird Cassin's auklet (Ptychoramphus aleuticus), a demographically sensitive indicator of marine climate change. We use future climate projections for sea surface temperature and upwelling intensity from a regional climate model to forecast changes in the population growth rate of the auklet population at the important Farallon Island colony in central California. Our study projected that the auklet population growth rate will experience an absolute decline of 11–45% by the end of the century, placing this population on a trajectory toward extinction. In addition, future changes in upwelling intensity and timing of peak upwelling are likely to vary across auklet foraging regions in the California Current Ecosystem (CCE), producing a mosaic of climate conditions and ecological impacts across the auklet range. Overall, the Farallon Island Cassin's auklet population has been declining during recent decades, and ocean climate change in this century under a mid‐level emissions scenario is projected to accelerate this decline, leading toward population extinction. Because our study species has proven to be a sensitive indicator of oceanographic conditions in the CCE and a powerful predictor of the abundance of other important predators (i.e. salmon), the significant impacts we predicted for the Cassin's auklet provide insights into the consequences that ocean climate change may have for other plankton predators in this system.     

Rates and consequences of relaying in Cassin's auklets Ptychoramphus aleuticus and rhinoceros auklets Cerorhinca monocerata breeding in a seasonal environment

We removed first eggs from early‐laying females to measure rates and consequences of relaying in Cassin's auklets Ptychoramphus aleuticus and rhinoceros auklets Cerorhinca monocerata at Triangle Island, British Columbia, Canada. Based on egg size and composition, the investment that Cassin's auklets made in first eggs was very close to that predicted from adult body mass, whereas rhinoceros auklets invested more. In both species, a high percentage of females relaid (90% of Cassin's and 87% of rhinoceros auklets). Breeding success declined weakly with later laying among control Cassin's auklet pairs, but pairs that we induced to relay bred more successfully than naturally late pairs, and similar to values predicted from laying dates of their first eggs. Their chicks also fledged heavier and younger than late control chicks, and similar to values in early control chicks, but followed the population‐wide seasonal decline in wing length at fledging. Nestling diets were dominated by Neocalanus copepods until late in the season, a sign that feeding conditions remained favourable until late. In contrast, rhinoceros auklet pairs induced to relay followed the population‐wide seasonal decline in breeding success, which was driven by a decline in hatching success. Pacific sandlance Ammodytes hexapterus, thought to be a preferred prey species, virtually disappeared from nestling diets in mid‐to‐late season, yet there was no seasonal decline in fledging mass. However, chicks from replacement eggs followed the declines among control chicks in both age and wing length at fledging. Despite the female having produced a replacement egg, and despite delayed breeding, there appeared to be little immediate consequence associated with relaying for Cassin's auklets, except for a tendency for their chicks to fledge with short wings. Consequences were more marked in rhinoceros auklets (greatly reduced hatching success, and having their chicks fledge with short wings), and this may have been due to the large investment made in eggs, and/or to delayed breeding. Results of this study show that attributes of Cassin's and rhinoceros auklets that lay at different times in the season can be important in driving seasonal declines in breeding performance, as found in studies on other Alcidae. They also show how decisions taken during the egg stage can have variable yet potentially important implications for fitness, even in relatively long‐lived species that lay single‐egg clutches.     

Limited consequences of infestation with a blood‐feeding ectoparasite for the nestlings of two North Pacific seabirds

The seabird tick Ixodes uriae parasitizes over 60 host species in the circumpolar regions of both hemispheres. To assess the impacts of these ticks on the growth and development of nestling seabirds, we used a logistic growth model to interpolate between successive measures of mass (g) and wing chord (mm) for 558 Cassin's auklet Ptychoramphus aleuticus and 344 rhinoceros auklet Cerorhinca monocerata chicks over 11 years (1997–2008, less 2003) on Triangle Island, British Columbia, Canada. From the model, we estimated the asymptotic measure and the age at inflection point for each chick's growth trajectory, and assessed their relationships with tick load relative to other sources of annual and seasonal variation in growth. Most chicks (72.4% of Cassin's auklets, 62.2% of rhinoceros auklets) hosted ≥ 1 ticks, and the median tick load on infested chicks was two in both species. Infestation rates varied by a factor of about two among years (0.42 to 0.87 overall), but were uncorrelated between species and with air temperatures over the preceding winter. The probability of hosting a tick declined strongly with chick age, mainly in the first 20 days after hatching, and to near zero by fledging. Asymptotic weights and/or wing lengths declined with tick load in both species, but at normal loads the reductions were minor relative to those imposed by other factors; only at very high loads, which were rare, were effects likely to be biologically relevant. Tick load and survival to fledging were unrelated in both species. While our study found little influence of ticks, we believe there is need for further study of the relationships between parasites and seabird demography, especially in light of ongoing environmental change.     

Oceanographic drivers of offspring abundance may increase or decrease reproductive variance in a temperate marine fish

In species that reproduce into uncertain environments, the relationship between mean reproductive success (the abundance of new recruits) and the variance in reproductive success (whether adults contribute disproportionally more offspring) may not be straightforward because of stochastic environmental processes that create high variance in reproductive success among adults. In this study, we investigated the relationships between oceanography, reproductive success and reproductive variance in the black rockfish, Sebastes melanops, a long‐lived temperate reef fish with pelagic larvae. We quantified black rockfish recruitment, genetic diversity and growth rates from otolith microstructure over 5 years (2005–2009) during which oceanographic conditions differed. We used cross‐correlations to determine windows of time during which oceanographic variables were significantly correlated with the resulting abundance or genetic diversity of recruits. We found that warmer ocean temperatures were positively correlated with the abundance of recruits, as well as the effective number of breeders. In contrast, the strength of coastal upwelling during settlement was positively correlated with the annual abundance of new recruits, but was negatively correlated with the effective number of breeders. Larval growth rates were explained substantially more by temperature than by upwelling and suggested that temperature affected survival through growth, while upwelling affected survival through transport. Our results indicated that cold ocean temperatures and intense upwelling caused sweepstakes‐like processes to operate on black rockfish populations, despite high abundances of recruits. We propose that a decoupling of the mean and variance in reproductive success may be characteristic of organisms that reproduce into uncertain environments.     

Linking seasonal distribution patterns with prey availability in a central-place forager, the Steller sea lion

Aim We used a novel approach to infer foraging areas of a central‐place forager, the Steller sea lion (Eumetopias jubatus), by assessing changes in the temporal and spatial distribution patterns of sea lions at terrestrial sites. Specifically, our objectives were (1) to classify seasonal distribution patterns of Steller sea lions and (2) to determine to what extent the seasonal distribution of Steller sea lions is explained by seasonal concentrations of prey. Location Southeast Alaska, USA. Methods Steller sea lions of all age classes were counted monthly (2001–04) by aerial surveys at 28 terrestrial sites. Hierarchical cluster analysis and principal components analysis were used to classify seasonal distribution patterns of Steller sea lions at these terrestrial sites. We estimated the proportion of sea lions in the study area that were associated with each seasonal distribution pattern. Results Multivariate ordination techniques revealed four distinct seasonal distributional patterns. During December, 55% of the sea lions in the study area were found at Type 1 sites, located near over‐wintering herring aggregations. During May, 56% of sea lions were found at Type 2 sites, near aggregations of spring‐spawning forage fish. In July, 78% of sea lions were found at Type 3 sites, near summer migratory corridors of salmon. During September, 44% of sea lions were found at Type 4 sites, near autumn migratory corridors of salmon. Main conclusions Seasonal attendance patterns of sea lions were commonly associated with the seasonal availability of prey species near terrestrial sites and reflected seasonal foraging patterns of Steller sea lions in Southeast Alaska. A reasonable annual foraging strategy for Steller sea lions is to forage on herring (Clupea pallasii) aggregations in winter, spawning aggregations of forage fish in spring, salmon (Oncorhynchus spp.) in summer and autumn, and pollock (Theragra chalcogramma) and Pacific hake (Merluccius productus) throughout the year. The seasonal use of haulouts by sea lions and ultimately haulout‐specific foraging patterns of Steller sea lions depend in part upon seasonally available prey species in each region.     

Seasonal foraging movements and migratory patterns of female Lamna ditropis tagged in Prince William Sound, Alaska

Conventional and electronic tags were used to investigate social segregation, distribution, movements and migrations of salmon sharks Lamna ditropis in Prince William Sound, Alaska. Sixteen salmon sharks were tagged with satellite transmitters and 246 with conventional tags following capture, and were then released in Prince William Sound during summer 1999 to 2001. Most salmon sharks sexed during the study were female (95%), suggesting a high degree of sexual segregation in the region. Salmon sharks congregated at adult Pacific salmon Oncorhynchus spp. migration routes and in bays near Pacific salmon spawning grounds in Prince William Sound during July and August. Adult Pacific salmon were the principal prey in 51 salmon shark stomachs collected during summer months in Prince William Sound, but the fish appeared to be opportunistic predators and consumed sablefish Anoplopoma fimbria, gadids, Pacific herring Clupea pallasi, rockfish Sebastes spp. and squid (Teuthoidea) even when adult Pacific salmon were locally abundant. As Pacific salmon migrations declined in late summer, the salmon sharks dispersed; some continued to forage in Prince William Sound and the Gulf of Alaska into autumn and winter months, while others rapidly moved south‐east thousands of kilometres toward the west coasts of Canada and the U.S. Three movement modes are proposed to explain the movement patterns observed in the Gulf of Alaska and eastern North Pacific Ocean: ‘focal foraging’ movements, ‘foraging dispersals’ and ‘direct migrations’. Patterns of salmon shark movement are possibly explained by spatio‐temporal changes in prey quality and density, an energetic trade‐off between prey availability and water temperature, intra‐specific competition for food and reproductive success. Transmissions from the electronic tags also provided data on depth and water temperatures experienced by the salmon sharks. The fish ranged from the surface to a depth of 668 m, encountered water temperatures from 4·0 to 16·8° C and generally spent the most time above 40 m depth and between 6 and 14° C (60 and 73%, respectively).     

The Morphology and Periodic Structures of the Otolith of the Chinook Salmon (Oncorhynchus tshawytscha), and Temperature-dependent Variation in Otolith Microscopic Growth Increment Width

The otolith (sagitta) of the chinook salmon (Oncorhynchus tshawytscha) has a variable external crystalline morphology which is related to differences in the growth rate of crystals in different parts of the otolith. The internal crystal structure of the otolith is complex with different mineral phases in different growth fields of the otolith and a well-defined series of microscopic growth increments in both the dorsal and the ventral parts (orientation in situ) of the otolith. The period of the microscopic growth increments was shown, by both a rearing experiment and interpolation from fish of known age, to be daily. By rearing sibling chinook salmon at different temperatures (while still maintaining them on the same diet) it was shown that the width of the daily growth increment varies with temperature, but neither multi- nor sub-daily increments appear in the area of regular, daily growth incrementation. Inclusions of the vaterite morph of calcium carbonate crystallizing in the botryoidal habit occur in the otherwise aragonitic otolith. Regularly spaced check rings in the sulcul part of the otolith are homologous with those occurring in the dorsal and ventral growth axis and are. on average, separated by about 28 microincrements.     

Validation and efficacy of transgenerational mass marking of otoliths in viviparous fish larvae

Transgenerational mass marking of viviparous fish larvae in vivo was validated by intra‐muscular injection of elemental strontium chloride (SrCl₂) in gestating females and detection of the Sr in the otoliths of developing larvae. All otoliths of brown rockfish Sebastes auriculatus larvae produced from SrCl₂‐injected females showed enriched Sr:Ca ratios near the otolith edges, and the signatures did not appear to be affected by the anterior, centre and posterior positions of larvae within the ovary. Results from the present study indicate that transgenerational marking is a highly reliable technique for marking large numbers of extremely small viviparous fish larvae.     

Main stem and off‐channel habitat use by juvenile Chinook salmon in a sub‐Arctic riverscape

相似文献   

Increasing variance in North Pacific climate relates to unprecedented ecosystem variability off California

Changes in variance are infrequently examined in climate change ecology. We tested the hypothesis that recent high variability in demographic attributes of salmon and seabirds off California is related to increasing variability in remote, large‐scale forcing in the North Pacific operating through changes in local food webs. Linear, indirect numerical responses between krill (primarily Thysanoessa spinifera) and juvenile rockfish abundance (catch per unit effort (CPUE)) explained >80% of the recent variability in the demography of these pelagic predators. We found no relationships between krill and regional upwelling, though a strong connection to the North Pacific Gyre Oscillation (NPGO) index was established. Variance in NPGO and related central Pacific warming index increased after 1985, whereas variance in the canonical ENSO and Pacific Decadal Oscillation did not change. Anthropogenic global warming or natural climate variability may explain recent intensification of the NPGO and its increasing ecological significance. Assessing non‐stationarity in atmospheric‐environmental interactions and placing greater emphasis on documenting changes in variance of bio‐physical systems will enable insight into complex climate‐marine ecosystem dynamics.     

Seasonal variation in the thermal performance of juvenile Atlantic salmon (Salmo salar)

1. Experimental data on the maximum growth and food consumption of winter‐acclimatised Atlantic salmon (Salmo salar) juveniles from three Norwegian rivers situated at 59 and 70°N were compared with predictions from published models of growth and food consumption of summer‐acclimatised fish from the same populations. 2. All winter‐acclimatised fish maintained positive growth and a substantial energy intake over the whole range of experimental temperature (1–6 °C). This contrasted with predictions from growth models based on summer acclimatised Atlantic salmon, where growth and energy intake ceased at approximately 5 °C. 3. Growth and food consumption varied significantly among populations. Winter‐acclimatised fish from a Northern population had a higher mass‐specific growth rate, higher energy intake and higher growth efficiency than southern populations, which is contrary to predictions from models developed using summer‐acclimatised salmon, where fish from the Northern population had the lowest growth efficiency. 4. The experiment provides evidence that thermal performance varies seasonally and suggests adaptation to the annual thermal regime.     

Differential growth in estuarine and freshwater habitats indicated by plasma IGF1 concentrations and otolith chemistry in Dolly Varden Salvelinus malma

This study employed a combination of otolith microchemistry to indicate the recent habitat use, and plasma concentrations of the hormone insulin‐like growth factor 1 (IGF1) as an index of recent growth rate, to demonstrate differences in growth and habitat use by Dolly Varden Salvelinus malma occupying both freshwater and estuarine habitats in south‐west Alaska. Extensive sampling in all habitats revealed that fish had higher IGF1 levels in estuarine compared to lake habitats throughout the summer, and that the growth rates in different habitats within the estuary varied seasonally. In addition, otolith microchemistry indicated differentiation in estuarine habitat use among individual S. malma throughout summer months. Although growth in the estuary was higher than in fresh water in nearly all sites and months, the benefits and use of the estuarine habitats varied on finer spatial scales. Therefore, this study further illustrates the diverse life histories of S. malma and indicates an evaluation of the benefits of marine waters needs to include sub‐estuary scale habitat use.     

Capacitative calcium entry and proliferation of human osteoblast-like MG-63 cells

Abstract. Adult bone tissue is continuously being remodelled and bone mass is maintained by a balance between osteoclastic bone resorption and osteoblastic bone formation. Alteration of osteoblastic cell proliferation may account in part for lack of balance between these two processes in bone loss of osteoporosis. There is calcium (Ca²⁺) control in numerous cellular functions; however, involvement of capacitative Ca²⁺ entry (CCE) in proliferation of bone cells is less well investigated. Objectives: The study described here was aimed to investigate roles of CCE in the proliferation of osteoblast‐like MG‐63 cells. Meterials and Methods: Pharmacological characterizations of CCE were undertaken in parallel, with evaluation of the expression of transient receptor potential canonical (TRPC) channels and of cell proliferation. Results: Intracellular Ca²⁺ store depletion by thapsigargin induced CCE in MG‐63 cells; this was characterized by a rapid transient increase of intracellular Ca²⁺ followed by significant CCE, induced by conditions that stimulated cell proliferation, namely serum and platelet‐derived growth factor. Inhibitors of store‐operated Ca²⁺ channels (2‐APB and SKF‐96365) prevented CCE, while voltage‐dependent Ca²⁺ channel blockers had no effect. Expression of various TRPC channels was shown in the cells, some having been shown to be responsible for CCE. Voltage‐dependent Ca²⁺ channel blockers had no effect on osteoblast proliferation while thapsigargin, 2‐APB and SKF‐96395, inhibited it. Cell cycle analysis showed that 2‐APB and SKF‐96395 lengthen the S and G₂/M phases, which would account for the reduction in cell proliferation. Conclusions: Our results indicate that CCE, likely attributed to the activation of TRPCs, might be the main route for Ca²⁺ influx involved in osteoblast proliferation.     

The relationship between otolith size and estimated age of tigertooth croaker (Otolithes ruber Bloch and Schneider, 1801) in Oman Sea,Iran

The relationships between somatic growth and otolith dimensions, otolith size to estimated age and growth parameters of the tigertooth croaker (Otolithes ruber) were investigated in 100 specimens (size range: 19.1–52.0 cm, total length) from the Oman Sea area, September 2014. All 100 otoliths were sectioned and determined by age. The oldest specimen was a 4.5‐year‐old female with a total length of 40.6 cm; the youngest specimen was also a female estimated at 1 year of age with a total length of 19.1 cm. The von Bertalanffy growth equation was estimated as L_t = 54.70 (1 ? exp (?0.37 (t + 0.21))). Concluded was that there is a significant relationship between body size, otolith dimensions and estimated age of Otolithes ruber.     

Otolith elemental signatures reflect residency in coastal water masses

We examined variability in otolith chemistry of wild caught fish in relation to in situ temperature and salinity within the California Current System. Barium, magnesium, and iron from the most recent growth zone in otoliths differentiated pelagic juvenile shortbelly rockfish (Sebastes jordani) residing in water masses with distinct temperature and salinity properties from central and southern California spanning nearly 500 km of coastline. The 3-element signature also discriminated fish that resided in different water masses that were associated with mesoscale cyclonic eddy circulation in the Santa Barbara Channel. Variability in otolith chemistry reflected the spatial patterns of both horizontal gradients and vertical gradients in water mass properties related to circulation. Although we found that the concentrations of particular elements in otoliths were correlated to ambient temperature or salinity, we suggest that these parameters are more useful as an identifying signature of distinct water masses associated with unique otolith signatures rather than as factors directly affecting otolith chemistry. Other factors varying among the water masses or among the fish populations residing in the water masses may also affect otolith chemistry. We discuss how oceanographic phenomena associated with the 1997–1998 El Niño and the persistent, recirculating eddy in the Channel may have affected coastal ocean conditions and variation in otolith chemistry of fish in the study area.     

Temperature effects on otolith pattern formation in Atlantic cod Gadus morhua

The effect of food intake and temperature on otolith macrostructure and microstructure was examined experimentally in Atlantic cod Gadus morhua. Daily increment formation was validated and otolith accretion rate and optical density quantified using image analysis. Two‐week periods of starvation had no discernable effect on otolith increment width or optical density, despite having negative effects on somatic growth. In contrast, temperature had a strong positive effect on otolith accretion rate and clear effects on optical density with the otolith becoming more translucent at higher temperatures. Somatic growth, otolith accretion and otolith optical density each had a significantly different response curve to temperature. No relationship was detected between individual somatic growth rates and the accretion rate or optical properties of the otolith. The experimental manipulation of temperature‐induced otolith patterns similar to the ‘false ring’ secondary structures sometimes observed in the otoliths of wild fish. The results suggest that otolith pattern arises from a combination of temperature and seasonal effects, but not directly from individual variation in somatic growth.     

Using otolith chemical and structural analysis to investigate reservoir habitat use by juvenile Chinook salmon Oncorhynchus tshawytscha

Isotopic composition of ⁸⁷Sr:⁸⁶Sr and natural elemental tracers (Sr, Ba, Mg, Mn and Ca) were quantified from otoliths in juvenile and adult Chinook salmon Oncorhynchus tshawytscha to assess the ability of otolith microchemistry and microstructure to reconstruct juvenile O. tshawytscha rearing habitat and growth. Daily increments were measured to assess relative growth between natal rearing habitats. Otolith microchemistry was able to resolve juvenile habitat use between reservoir and natal tributary rearing habitats (within headwater basins), but not among catchments. Results suggest that 90% (n = 18) of sampled non‐hatchery adults returning to the Middle Fork Willamette River were reared in a reservoir and 10% (n = 2) in natal tributary habitat upstream from the reservoir. Juveniles collected in reservoirs had higher growth rates than juveniles reared in natal streams. The results demonstrate the utility of otolith microchemistry and microstructure to distinguish among rearing habitats, including habitats in highly altered systems.     

Aerobic and anaerobic enzyme assays in Southern California Rockfish: Proxies for physiological and ecological data

Rockfish are commercially and recreationally important, yet due to the depths they inhabit (3-500 m), little is known about their ecology. The present study examined 19 different species of Sebastes from the Southern California Bight over four seasons (late summer, fall, early winter, and spring) using metabolic enzyme assays. Enzymes used were lactate dehydrogenase (LDH), malate dehydrogenase (MDH), pyruvate kinase (PK), and citrate synthase (CS). Muscle proximate composition data (protein, water and lipid content) were also used to help interpret the enzyme data. Enzyme activity was lowest in the summer when expressed as activity per gram wet weight but when it was expressed per gram protein the trend was reversed. The rockfish have the highest protein as a percentage of wet mass (P%WM) in the spring, right before the upwelling period begins and the lowest P%WM in late summer after the peak of upwelling. Lipid content also showed a seasonal change with the highest lipid content in the late summer and the lowest in winter. The enzyme profiles have been broken into three groups which fit with their locomotory habit and their prey selection. These findings show that enzymes and muscle proximate composition can be used along with limited observational data on related species to deduce condition, seasonal impacts and ecologically important life habits in species that are difficult to observe and monitor.     

Sensitivity of salmonid freshwater life history in western US streams to future climate conditions

We projected effects of mid‐21st century climate on the early life growth of Chinook salmon (Oncorhynchus tshawytscha) and steelhead (O. mykiss) in western United States streams. Air temperature and snowpack trends projected from observed 20th century trends were used to predict future seasonal stream temperatures. Fish growth from winter to summer was projected with temperature‐dependent models of egg development and juvenile growth. Based on temperature data from 115 sites, by mid‐21st century, the effects of climate change are projected to be mixed. Fish in warm‐region streams that are currently cooled by snow melt will grow less, and fish in suboptimally cool streams will grow more. Relative to 20th century conditions, by mid‐21st century juvenile salmonids' weights are expected to be lower in the Columbia Basin and California Central Valley, but unchanged or greater in coastal and mountain streams. Because fish weight affects fish survival, the predicted changes in weight could impact population fitness depending on other factors such as density effects, food quality and quantity changes, habitat alterations, etc. The level of year‐to‐year variability in stream temperatures is high and our analysis suggests that identifying effects of climate change over the natural variability will be difficult except in a few streams.     

Varying effects of anadromous sockeye salmon on the trophic ecology of two species of resident salmonids in southwest Alaska

1. Anadromous salmon transport marine‐derived nutrients and carbon to freshwater and riparian ecosystems upon their return to natal spawning systems. The ecological implications of these subsidies on the trophic ecology of resident fish remain poorly understood despite broad recognition of their potential importance. 2. We studied the within‐year changes in the ration size, composition and stable isotope signature of the diets of two resident salmonids (rainbow trout, Oncorhynchus mykiss; Arctic grayling, Thymallus arcticus) before and after the arrival of sockeye salmon (Oncorhynchus nerka) to their spawning grounds in the Bristol Bay region of southwest Alaska. 3. Ration size and energy intake increased by 480–620% for both species after salmon arrived. However, the cause of the increases differed between species such that rainbow trout switched to consuming salmon eggs, salmon flesh and blowflies that colonized salmon carcasses, whereas grayling primarily ate more benthic invertebrates that were presumably made available because of physical disturbances by spawning salmon. 4. We also observed an increase in the δ¹⁵N of rainbow trout diets post‐salmon, but not for grayling. This presumably led to the observed increase in the δ¹⁵N of rainbow trout with increasing body mass, but not for grayling. 5. Using a bioenergetics model, we predicted that salmon‐derived resources contributed a large majority of the energy necessary for growth in this resident fish community. Furthermore, the bioenergetics model also showed how seasonal changes in diet affected the stable isotope ratios of both species. These results expand upon a growing body of literature that highlights the different pathways whereby anadromous salmon influence coastal ecosystems, particularly resident fish.