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1.
Seasonal and long-term variations in the body size of planktonic copepods in the northern Baltic Sea 总被引:2,自引:3,他引:2
Seasonal and long-term variations in the body size of planktonic copepods were studied in the northern Baltic Sea. The influence of temperature, salinity and phytoplankton concentration to the body size of Eurytemora affinis, Acartia bifilosa and Limnocalanus macrurus (Calanoida) was examined at three sea areas, differing in their hydrographical and trophic conditions (an archipelago area and an enclosed bay on the SW coast of Finland in 1992 and at an open sea station in the Gulf of Bothnia in 1991). There was an inverse relationship between copepod body length and temperature, while there was a direct effect of phytoplankton concentration. According to multiple regression analysis, the relative importance of these factors varied according to species, developmental stage and study area. In the archipelago area, copepod body size was mainly determined by temperature, while in the open Gulf of Bothnia, phytoplankton concentration was usually more important. Interannual variation in the summer body length of E. affinis and A. bifilosa was examined using samples collected over 18 years (1967 to 1984) in the archipelago area. In this analysis, the inverse relationship between water temperature and copepod body size disappeared; in E. affinis the average female length correlated positively with summer temperature. We suggest that the length and timing of the study period greatly influence the investigator's view of the factors regulating copepod body size. 相似文献
2.
Three strains of the chain-forming diatom Skeletonema marinoi, differing in their production of polyunsaturated aldehydes (PUA) and nutritional food components, were used in experiments
on feeding, egg production, hatching success, pellet production, and behavior of three common planktonic copepods: Acartia tonsa, Pseudocalanus elongatus, and Temora longicornis. The three different diatom strains (9B, 1G, and 7J) induced widely different effects on Acartia tonsa physiology, and the 9B strain induced different effects for the three copepods. In contrast, different strains induced no
or small alterations in the distribution, swimming behavior, and turning frequency of the copepods. 22:6(n-3) fatty acid (DHA)
and sterol content of the diet typically showed a positive effect on either egg production (A. tonsa) or hatching success (P. elongatus), while other measured compounds (PUA, other long-chain polyunsaturated fatty acids) of the algae had no obvious effects.
Our results demonstrate that differences between strains of a given diatom species can generate effects on copepod physiology,
which are as large as those induced by different algae species or groups. This emphasizes the need to identify the specific
characteristics of local diatoms together with the interacting effects of different mineral, biochemical, and toxic compounds
and their potential implications on different copepod species. 相似文献
3.
The Baltic Sea is a very suitable site for stoichiometric studies, since its subbasins differ in their concentration of elemental components, and primary production can therefore be either nitrogen or phosphorus limited. To reveal if the nutrient limitation of mesozooplankton mirrors that of the primary producers, carbon, nitrogen and phosphorus content of both seston and grazers (Acartia sp., Centropages hamatus, Daphnia cristata, Eurytemora affinis, Limnocalanus macrurus, Temora longicornis) were measured in midsummer in the Baltic proper, the Gulf of Finland and the Gulf of Bothnia. The mineral ratios of the different taxa were equal, apart from L. macrurus with notably higher C:P and N:P ratios. Molar C:N ratios were relatively stable (5.1-6.3), whereas C:P and N:P ratios fluctuated more (41-144 and 6.6-24). However, zooplankton elemental composition and limitation did not depend on the limiting nutrient of the phytoplankton, the seston mineral ratio or the sea area. Both the seston-zooplankton elemental imbalance and the food threshold ratio indicated phosphorus limitation of most of the grazers. While L. macrurus may be C or N limited, the possible P deficiency of the other studied taxa suggests that the Baltic Sea zooplankton may act as a potential phosphorus sink, as the freshwater secondary producers do. 相似文献
4.
ABSTRACT: In‐reservoir thermal and ecological effects of releasing some flows over the surface spillway at Blue Mesa Reservoir, Colorado, rather than routing all releases through the hypolimnetic outlet were evaluated using a calibrated and validated one‐dimensional thermal model (CE‐THERM) with a set of ecological models. Thermal model output indicated that surface water temperatures were influenced primarily by atmospheric conditions, but the release of warmer water over the spillway resulted in a thinner epilimnion and cooler metalimnetic water temperatures. Ecological model predictions indicated that spillway releases and associated temperatures resulted in lower growth rates for young‐of‐year (YOY) kokanee salmon (Oncorhynchus nerka) in the reservoir by up to 9 percent when compared with growth rates under baseline operations with no releases over the spillway. Kokanee growth rates were reduced under spillway release scenarios because lower temperatures not only affected metabolic rates, but limited the productivity of the zooplankton as well. Thus, altering the release regime with spillway discharges could have deleterious effects on Blue Mesa's YOY kokanee. However, in other reservoirs, distributing discharges among different elevations may provide managers with a mechanism to regulate temperatures to benefit species of concern that are facing challenges imposed by environmental conditions such as global warming. 相似文献
5.
Kenneth B. Raposa Marci L. Cole Ekberg David M. Burdick Nicholas T. Ernst Susan C. Adamowicz 《Regional Environmental Change》2017,17(2):389-397
Salt marshes persist within the intertidal zone when marsh elevation gains are commensurate with rates of sea-level rise (SLR). Monitoring changes in marsh elevation in concert with tidal water levels is therefore an effective way to determine if salt marshes are keeping pace with SLR over time. Surface elevation tables (SETs) are a common method for collecting precise data on marsh elevation change. Southern New England is a hot spot for SLR, but few SET elevation change datasets are available for the region. Our study synthesizes elevation change data collected from 1999 to 2015 from a network of SET stations throughout Rhode Island (RI). These data are compared to accretion and water level data from the same time period to estimate shallow subsidence and determine whether marshes are tracking SLR. Salt marsh elevation increased at a mean overall rate of 1.40 mm year?1 and ranged from ?0.33 to 3.36 mm year?1 at individual stations. Shallow subsidence dampened elevation gain in mid-Narragansett Bay marshes, but in other areas of coastal RI, subsurface processes may augment surface accretion. In all cases, marsh elevation gain was exceeded by the 5.26 mm year?1 rate of increase in sea levels during the study period. Our study provides the first SET elevation change data from RI and shows that most RI marshes are not keeping pace with short- or long-term rates of SLR. It also lends support to previous research that implicates SLR as a primary driver of recent changes to southern New England salt marshes. 相似文献
6.
Developing a Monitoring Protocol for Visitor-Created Informal Trails in Yosemite National Park,USA 总被引:1,自引:0,他引:1
Informal trails created or perpetuated by visitors is a management challenge in many protected natural areas such as Yosemite
National Park. This is a significant issue as informal trail networks penetrate and proliferate into protected landscapes
and habitats, threatening ecological integrity, aesthetics, and visitor experiences. In order to develop effective strategies
for addressing this problem under an adaptive management framework, indicators must be developed and monitoring protocol must
be established to gather timely and relevant data about the condition, extent, and distribution of these undesired trail segments.
This article illustrates a process of developing and evaluating informal trail indicators for meadows in Yosemite Valley.
Indicator measures developed in past research were reviewed to identify their appropriateness for the current application.
Information gaps in existing indicator measures were addressed by creating two new indices to quantify the degree of informal
trailing based on its land fragmentation effects. The selected indicator measures were applied to monitoring data collected
between 2006 and 2008. The selected measures and indices were evaluated for their ability to characterize informal trail impacts
at site and landscape scales. Results demonstrate the utility of indicator measures in capturing different characteristics
of the informal trail problem, though several metrics are strongly related to each other. The two fragmentation indices were
able to depict fragmentation without being too sensitive to changes in one constituent parameter. This study points to the
need for a multiparameter approach to informal trail monitoring and integration with other monitoring data. Implications for
monitoring programs and research are discussed. 相似文献
7.
Sonja E. Koski 《Behavioral ecology and sociobiology》2011,65(11):2161-2174
Animals of many species show consistency in behaviour across time and contexts that differs from other individuals' behaviour
in the same population. Such ‘personality’ affects fitness and has therefore become an increasingly relevant research topic
in biology. However, consistent variation in social behaviour is understudied. In socially living species, behaviour occurs
in a social environment and social interactions have a significant influence on individual fitness. This study addressed personality
in social behaviour of 75 captive chimpanzees in three zoos by coding observed behaviour. Fifteen behavioural variables were
significantly repeatable (range 0.21–0.93) in at least two of the three zoos. The behaviours showed considerable long-term
stability across 3 years, which did not differ from the short-term repeatability. The repeatable behaviours were then analysed
with factor analyses. They formed five independent factors, three of which consisted of social traits and were labelled ‘sociability’,
‘positive affect’ and ‘equitability’. The two non-social behaviour factors were labelled ‘anxiety’ and ‘activity’. The factor
scores were analysed for sex and population differences. Males had higher factor scores in all traits except ‘sociability’.
The factor scores differed also between the zoos, implying considerable external effects in trait expression. The results
show that chimpanzees show personality in a broad range of social and non-social behaviours. The study highlights the importance
of assessing personality in the social behaviour, especially in cohesive social species, as only then can we understand the
consequences of personality in socially living species. 相似文献
8.
Wigand C McKinney RA Cole ML Thursby GB Cummings J 《Environmental monitoring and assessment》2007,131(1-3):71-81
The stable nitrogen isotope ratios of some biota have been used as indicators of sources of anthropogenic nitrogen. In this
study the relationships of the stable nitrogen isotope ratios of marsh plants, Iva frutescens (L.), Phragmites australis (Cav.) Trin ex Steud, Spartina patens (Ait.) Muhl, Spartina alterniflora Loisel, Ulva lactuca (L.), and Enteromorpha intestinalis (L.) with wastewater nitrogen and land development in New England are described. Five of the six plant species (all but U. lactuca) showed significant relationships of increasing δ
15N values with increasing wastewater nitrogen. There was a significant (P < 0.0001) downward shift in the δ
15N of S. patens (6.0 ± 0.48‰) which is mycorrhizal compared with S. alterniflora (8.5 ± 0.41‰). The downward shift in δ
15N may be caused by the assimilation of fixed nitrogen in the roots of S. patens. P. australis within sites had wide ranges of δ
15N values, evidently influenced by the type of shoreline development or buffer at the upland border. In residential areas,
the presence of a vegetated buffer (n = 24 locations) significantly (P < 0.001) reduced the δ
15N (mean = 7.4 ± 0.43‰) of the P. australis compared to stands where there was no buffer (mean = 10.9 ± 1.0‰; n = 15). Among the plant species, I. frutescens located near the upland border showed the most significant (R
2 = 0.64; P = 0.006) inverse relationship with the percent agricultural land in the watershed. The δ
15N of P. australis and I. frustescens is apparently an indicator of local inputs near the upland border, while the δ
15N of Spartina relates with the integrated, watershed-sea nitrogen inputs. 相似文献
9.
Theerthagiri Jayaraman Karuppasamy K. Park Juhyeon Rahamathulla Nihila Kumari M. L. Aruna Souza Marciélli K. R. Cardoso Eduardo S. F. Murthy Arun Prasad Maia Gilberto Kim Hyun-Seok Choi Myong Yong 《Environmental Chemistry Letters》2023,21(3):1555-1583
Environmental Chemistry Letters - The decrease in fossil fuel usage and the projected 28% increase in the global energy demand by 2040 are calling for advanced methods to convert modern biomass... 相似文献
10.
Marja Koski 《Marine Biology》2007,151(5):1785-1798
Feeding, egg production, hatching success and early naupliar development of Calanus finmarchicus were measured in three north Norwegian fjords during a spring bloom dominated by diatoms and the haptophyte Phaeocystis pouchetii. Majority of the copepod diet consisted of diatoms, mainly Thalassiosira spp. and Chaetoceros spp., with clearance rates up to 10 ml ind−1 h−1 for individual algae species/groups. Egg production rates were high, ranging from ca 40 up to 90 eggs f−1 d−1, with a hatching success of 70–85%, and fast naupliar development through the first non-feeding stages. There was no correlation
between the egg or nauplii production and diatom abundance, but the hatching success was slightly negatively correlated with
diatom biomass. However, the overall high reproductive rates suggested that the main food items were not harmful for C. finmarchicus reproduction in the area, although direct chemical measurements were not conducted. The high population egg production (>1,20,000
eggs m−2 d−1) indicated that a large part of the annual reproduction took place during the investigation, which stresses the importance
of diatom-dominated spring phytoplankton bloom for population recruitment of C. finmarchicus in these northern ecosystems. 相似文献