Fluctuations In Biomass Research Articles

Dynamics of Culturable Soil Bacterial Communities During Pre‐Planting and Growing Soybean Season as Evaluated by Community Level Physiological Profiles

The agricultural practices used today for farming produce crops generate major effects on microbial ecosystems. At the same time, soil microbes can stimulate a wide range of impacts on growing crops. Since changes in soil microbial communities may reflect changes in soil quality or differences in soil management practices, we examined the effects of agricultural farming on the dynamics of soil microbial biomass and community structure. Soil samples were collected prior to planting (May 2019) and during the growing season (September 2019) from a non‐tilled agricultural soybean farm in Greencastle, IN. We quantified microbial biomass using phospholipid phosphate and quantified community structure using community level physiological profiling (CLPP) with Biolog EcoPlates. Soil samples were collected from four subplots in the agricultural field and a control sample from an adjacent woods plot. There was not a significant difference in the C/N ratios between the pooled agricultural plots (9.84) and the woods (9.96) in the pre‐planting season. We also did not see significant differences in C/N ratios among the agricultural subplots. Moisture content (Woods: 36.06% to 42.74%; Farm: 20.18% to 15.46%, from pre‐planting to growing season) was higher in the woods with a stable temperature regime. Consequently, there were no significant differences in the microbial biomass from pre‐planting (37.74 nmol PO□ gdw) to the growing season (41.48 nmol PO□ gdw) in the farm plots, but the woods (Pre‐planting: 44.63 nmol PO□ gdw; Growing: 119.57 nmol PO□ gdw) showed much more temporary fluctuation in biomass. In addition, there was a higher microbial biomass in the control plot compared to the agricultural plots during both the sampling periods. It is possible that seasonal changes are not reflected in microbial biomass on the agricultural plots due to the consistent C/N ratio or the agricultural farming of soybeans. The principal component analysis (PCA) of the CLPP indicated a broad scale of different metabolic functions of the soil microbial communities between the agricultural plots and the control. However, we did not observe any significant difference between the microbial communities of the agricultural plots from pre‐planting to the growing season. The dominant bacterial group present in the agricultural plots was Pseudomonadaceae, a common bacteria in soil, while in the control plot, the most dominant bacterial group was Enterobacteriaceae. Our results imply that a consistent organic input (C/N ratio) might sustain a stable microbial community and thus promote soil health, however, diverse factors such as crop growth stage, residue inputs, and soil physical and chemical conditions may contribute to soil quality and microbial communities. In order to determine the effects of root detritus of soybeans after harvest on soil health and microbial communities, it is recommended that sample collection and analysis occur following the harvest of the soybean crop.Support or Funding InformationScience Research Fellows Program; DePauw University

Local species diversity, β-diversity and climate influence the regional stability of bird biomass across North America.

Biodiversity often stabilizes aggregate ecosystem properties (e.g. biomass) at small spatial scales. However, the importance of species diversity within communities and variation in species composition among communities (β-diversity) for stability at larger scales remains unclear. Using a continental-scale analysis of 1657 North American breeding-bird communities spanning 20-years and 35 ecoregions, we show local species diversity and β-diversity influence two components of regional stability: local stability (stability of bird biomass within sites) and spatial asynchrony (asynchronous fluctuations in biomass among sites). We found spatial asynchrony explained three times more variation in regional stability of bird biomass than did local stability. This result contrasts with studies at smaller spatial scales-typically plant metacommunities under 1 ha-that find local stability to be more important than spatial asynchrony. Moreover, spatial asynchrony of bird biomass increased with bird β-diversity and climate heterogeneity (temperature and precipitation), while local stability increased with species diversity. Our study reveals new insights into the scale-dependent processes regulating ecosystem stability, providing evidence that both local biodiversity loss and homogenization can destabilize ecosystem processes at biogeographic scales.

New Methods for Microbiological Monitoring at Riverbank Filtration Sites

Water suppliers aim to achieve microbiological stability throughout their supply system by regular monitoring of water quality. Monitoring temporal biomass dynamics at high frequency is time consuming due to the labor-intensive nature and limitations of conventional, cultivation-based detection methods. The goal of this study was to assess the value of new rapid monitoring methods for quantifying and characterizing dynamic fluctuations in bacterial biomass. Using flow cytometry and two precise enzymatic detection methods, bacterial biomass-related parameters were monitored at three riverbank filtration sites. Additionally, the treatment capacity of an ultrafiltration pilot plant was researched using online flow-cytometry. The results provide insights into microbiological quality of treated water and emphasize the value of rapid, easy and sensitive alternatives to traditional bacterial monitoring techniques.

Specific oceanographic characteristics and phytoplankton responses influencing the primary production around the Ulleung Basin area in spring

The East Sea (Sea of Japan) is a marginal, semi-closed sea in the northwestern Pacific. The Ulleung Basin area, which is located near the subpolar front of the East Sea, is known to have high primary production and good fisheries in spring season. After episodic wind-driven events during the spring of 2017, horizontal and vertical profiles of physical chemical biological factors were investigated at 29 stations located in the Ulleung Basin area. In addition, growth responses of phytoplankton communities to nutrient additions were evaluated by bioassay experiments to understand the fluctuation of phytoplankton biomass. Because of strong northwestern wind, phytoplankton biomass was scattered and upwelling phenomenon might be suppressed in this season. The phytoplankton abundances in the coastal stations were significantly higher than offshore and island stations. In contrast, the nutrient and chlorophyll a (Chl a) concentrations and the phytoplankton biomass were quite low in all locations. Bacillariophyceae was dominated group (75.1% for coastal, 40.0% for offshore and 43.6% for island stations). In the algal bioassays, the phytoplankton production was stimulated by N availability. The in vivo Chl a values in the +N and +NP treatments were significantly higher than the values in the control and the +P treatments. Based on the field survey, the higher nutrients in coastal waters affected the growth of diatom assemblages, however, little prosperity of phytoplankton was observed in the offshore waters despite the injection of sufficient nutrients in bioassay experiments. The growth of phytoplankton depended on the initial cell density. All of results indicated that a dominant northwestern wind led to a limited nutrients condition at euphotic layers, and the low level of biomass supply from the coasts resulted in low primary production. Both supplying nutrients and introducing phytoplankton through the currents are critical to maintain the high productivity in the Ulleung Basin area of the East Sea.

General surface circulation controls the interannual fluctuations of anchovy stock biomass in the Central Mediterranean Sea

The sustainable exploitation of small pelagic fish populations, characterized by short life span and early age at first reproduction, is typically more influenced by the success of annual recruitment rather than by fishing mortality. Recruitment strength, in turn, is related to the high environmental variability characterizing the pelagic fish habitats, able to strongly affect the survival of early stages, from hatching to recruitment. Here, we consider the case study of anchovy (Engraulis encrasicolus) stock in the Strait of Sicily (Central Mediterranean). The interannual fluctuations exhibited over an 18-year long period by this fish population was found to be mainly linked to surface circulation patterns, as far as they are able to control retention/dispersal processes of larval stages. We firstly used Lagrangian simulations to reproduce the fate of anchovy early stages during their planktonic phase. Larval retention indices constructed from the output of the simulations were able alone to explain a large proportion of variance (up to 70%) in yearly biomass of the anchovy population, outclassing the other environmental factors considered in this study. Such results are relevant for fisheries management, for all fish stocks characterized by potentially high vulnerability of early life stages.

Fish trophic guild responses to damming: Variations in abundance and biomass

AbstractDams and associated reservoirs cause drastic changes in the composition and structure of ichthyofauna. Therefore, functional groups within a fish assemblage may respond distinctly to such human interventions in rivers. The objective of this study was to evaluate how fluctuations in fish abundance and biomass differ among trophic guilds. Fish were sampled before and after damming four reservoirs, in their inner areas (more heavily impacted areas) and upstream (less impacted areas). To evaluate possible changes, we used a before–after and control‐impact experimental design. Fish were classified into trophic guilds through diet analysis and based on information available from the literature. Six trophic guilds were identified. The effect of periods (before and after damming) and sites (more and less impacted) on abundance and biomass differed among the trophic guilds. Highly specialized trophic guilds, such as herbivores and detritivores, were negatively affected by damming. Invertivores were negatively affected in the impacted area and increased in abundance and biomass in the less impacted sites. The findings of this study show that modifications imposed by damming are reflected in the abundance and biomass of fish trophic guilds, but the degree of such impacts vary according to characteristics of the considered trophic guild.

The Periphyton Structural Organization on the Fibrous Carrier "Viya" over the Waste Waters Purification from the Oil Products

The paper deals with periphyton structural organization on the fibrous carrier «VIYA» in the waste water treatment plant of the "Motor Sich" plant. Taxonomic and trophic structure and seasonal fluctuations of numbers and biomass over the vegetation season of 2014 were studied.

Roles of fishing and climate change in long-term fish species succession and population dynamics in the outer Beibu Gulf, South China Sea

A prevailing, controversial hypothesis is that fishing pressure has played a greater role than climatic and environmental drivers, in changing fish species succession and biomass fluctuation in the South China Sea (SCS). Based on otter trawl survey data from 1959 to 2010 in the outer Beibu Gulf (OBG), northern SCS, large seasonal and interannual variation is reported for fish species composition, the proportional abundances of dominant taxa, and fish biomass. Generalized additive models are developed to quantify relationships between fish biomass and the external factors of fishing pressure and climate change. Fishing pressure proved to be the main driver of sharp declines in demersal fish stocks, with high-value species being replaced by low-value ones over time. Abrupt decreases in fish biomass during the years of 1993 and 1998 correspond to El Nino events, with climate change possibly the main driver of proportional representation of pelagic species in fisheries trawl catch. The need to differentiate impacts of fishing and environmental drivers on fish species with different life history strategies is stressed to better understand fish community dynamics.

Interannual Changes in the Quantitative Parameters and Structure of Invertebrates in the Littoral and Pelagic Zones of Lake Sevan (Armenia) with Fluctuations in Meteorological Conditions and Fish Biomass. II. Autumn Zooplankton

Interannual Changes in the Quantitative Parameters and Structure of Invertebrates in the Littoral and Pelagic Zones of Lake Sevan (Armenia) with Fluctuations in Meteorological Conditions and Fish Biomass. II. Autumn Zooplankton

Comparative analysis of terrestrial arthropod community and biomass in differently managed rice fields in Korea

The present study was conducted to investigate the differences in managed farming practices, including low-intensive farming, duck farming, and golden apple snail farming, in a rice ecosystem by comparing terrestrial arthropod communities. A total of 75 species from 70 genera belonging to 43 families in 11 orders were identified from 9,622 collected arthropods. Araneae, Hemiptera, and Coleoptera were the richest taxa. Collembola was the most abundant, followed by Diptera, Hemiptera, and Araneae. Bray- Curtis similarity among the farming practices was very high (76.7%). The biodiversity of each farming practice showed a similar seasonality pattern. The richest species group was the predators, followed by the herbivores. The species richness and diversity of ecologically functional groups among the farming practices were not statistically significant, except for the abundance of predators in golden apple snail farming. The biodiversity seasonality of ecological functional groups in each farming practice showed similar patterns. The biomass of Araneae, Hemiptera, Coleoptera, and Diptera was greater than the other taxa, in general. The biomass of each ecological functional group showed little difference and the biomass fluctuation patterns in each farming practice were almost the same. Collectively, the community structures and biodiversity of terrestrial arthropods among the farming practices in the present study were not different. The present study may contribute to sustain rich biodiversity in irrigated rice fields and to advanced studies of food webs or energy flow structures in rice fields for ecological and sustainable agriculture.

Competition among functional groups increases asynchrony of their temporal fluctuations in a temperate grassland

AbstractQuestionsWe asked whether the competition among community components (a) destabilizes individual components; (b) increases the asynchrony of their fluctuations; and (c) stabilizes the total community biomass.LocationSeminatural meadow in South Bohemia, Czech Republic.MethodsWe used biomass fluctuation data from a 13‐year removal experiment. The plots used for this study contained, following experimental removal of other species, either mycorrhizal grasses only, mycorrhizal forbs only, or their mixture (grass “monocultures”, forb “monocultures”, and mixtures, respectively). Yearly peak aboveground biomass was available from ten blocks; biomass of the mixture plots was sorted into forbs and grasses. Temporal variability was characterized by coefficient of variation (CV) and synchrony by correlation coefficient, both calculated from the time series data.ResultsThe variability of grass monocultures was higher than the variability of forb monocultures, which was slightly lower than the variability of mixtures. The variability of both grasses and forbs was higher in the mixture, where they are in competition with the other group, than in each of their respective monocultures. The correlation coefficients between the biomass of grass and forb monocultures within blocks were mostly positive, indicating that both groups tend to have similar physiological responses to weather fluctuations. The average correlation coefficient between the forbs and grasses in the mixture plots was significantly negative, thus reflecting the effect of competition between these two community components. The CV of the sum of forb and grass monocultures was similar to the CV of mixture plots.ConclusionsOnly competition between grasses and forbs leads to their negative mutual correlation, i.e., to compensatory dynamics. Our results support the hypothesis that competition has a destabilizing effect on individual community components (functional groups in our case) and increases asynchrony of their fluctuations. We have not found its stabilizing effect on the total biomass.

Interannual Changes in the Quantitative Parameters and Structure of Invertebrates in the Littoral and Pelagic Zones of Lake Sevan (Armenia) with Fluctuations in Meteorological Conditions and Fish Biomass. I. Summer Zooplankton

Annual changes in the quantitative characteristics and structure of zooplankton in the pelagic and littoral zones of Lake Sevan in October have been determined by a number of factors, among which the biomass of the main planktophage, whitefish (Coregonus lavaretus L., 1758), have the greatest effect. The richest communities form due to Cladocera upon a decreased biomass of whitefish, minimum increase in the water level, and high average monthly temperatures for the period of April–October. In the littoral zone, the zooplankton is affected by a number of unaccounted factors, and the influence of planktophagous fish, mainly inhabiting deepwater areas, is less pronounced. A significant increase in biomass of planktophagous fish in 2016–2017 leads to a reduction in the quantitative characteristics of zooplankton, resulting in decreased water clarity.

Nitrogen supply and other controls of carbon uptake of understory vegetation in a boreal Picea abies forest

In boreal forests, carbon (C) uptake by understory may be too large to be ignored and too variable in space to be assumed a constant fraction of the ecosystem gross primary production. To improve estimates of understory production in these ecosystems, we need to better account for its main controls. In this study, we estimated C uptake of field-layer vegetation, dominated by Vaccinium myrtillus, V. vitis-idaea, and Deschampsia flexuosa, in a boreal Picea abies stand in northern Sweden. Nitrogen (N) availability in the stand has been manipulated through annual N additions since 1996 at the rates of 0, 12.5, and 50 kg N ha−1 yr−1. To assess the relative importance of N supply, and interannual fluctuations in leaf biomass and weather, in controlling field-layer photosynthetic production, we calculated C uptake over eight growing seasons using a canopy photosynthesis model. Without N additions, tree leaf area index (L) was already high (8.5) and field-layer C uptake was small, 27 g C m−2 (or ∼3% of stand C uptake). An increase in tree L with N additions further reduced light availability for the understory, yet the concurrent increase in the relative abundance of the more physiologically active D. flexuosa sustained the contribution of the field-layer to stand photosynthetic production. Based on a literature survey, in which site quality or stand age generated a wide range in L, understory contribution to ecosystem C uptake increases linearly with the fraction of available light reaching the forest floor across high latitude forests. Understory contributes only ∼5% to ecosystem C uptake where trees intercept ∼80% of incoming light, increasing to 100% after clearcut tree harvest. While the availability of solar energy, both spatially and temporally, is the primary driver of understory production, our analyses suggest that the predicted increases in drought severity and frequency at high latitudes may affect understory communities more than trees. Future empirical and modeling studies should focus on functional and ecological responses to drought of not only trees but also understory species, which contribute to biodiversity and convert their photosynthates to important non-timber products.

МНОГОЛЕТНЯЯ ДИНАМИКА УЛОВОВ, ЧИСЛЕННОСТИ И БИОМАССЫ ПОПУЛЯЦИИ СУДАКА (SANDERLUCIOPERCA L.) БЕЛОГО ОЗЕРА

Until the end of the 20th century fish community in Beloye Lake had been mainly presented by smelt and zander, which resulted in the high volumes of the species catches, yearly variations changed synchronously. Dynamics of zander and smelt fishing in Lake Beloye in the period from 1940 to 2017 has been described. Since 1970s the volumes of their catch and the share in total catches have become gradually decreasing. The average catch made by the research trawl during 1 hour is taken as the main indicator of long-term fluctuations of abundance and biomass of zander population in Beloye Lake within 1970-2017. The main reason for the long-term decline of abundance of smelt and zander populations is the global warming. Smelt biomass rapidly declines in hot years, which results in a sharp decrease of the zander feed supply. The 6-7-year periods of massive reduction of abundance, biomass and catches of zander and smelt in Beloye Lake were recorded in the 1970s and 2000s. Against a background of a sharp decrease of smelt abundance, in 2001-2003 in Beloye Lake there were registered the most numerous zander generations, which caused a strong population imbalance. Thus, the abundance of small-sized fish increased in the 2000s and the commercial biomass of the population decreased rapidly, which led to a significant reduction of zander catches. Generally, against the outlined trend of climate warming, there grows the risk to lose the commercial status of reservation of the commercial status of smelt and zander populations in Beloye Lake in the future.

Metabolomic and transcriptomic analyses reveal the effects of ultraviolet radiation deprivation on Isochrysis galbana at high temperature

The microalga Isochrysis galbana exhibits a seasonal fluctuation of biomass referred to as ‘decline’ during summer, leading to a great economic loss in the mariculture industry. In the present study, we aimed to explore the role of ultraviolet radiation (UVR) in I. galbana decline at high temperature by integrated analysis of metabolomic and transcriptomic data. The positive effects of UVR deprivation on the growth and photosynthetic activity of I. galbana were preliminarily evidenced by the increase in biomass concentration, the effective photochemical efficiency of photosystem II (PSII) (Fv′/Fm′), and oxygen evolution rate. Furthermore, we compared the contents of eight organic acids, total lipids and gene expression of I. galbana grown under natural sunlight versus UVR-deprived conditions, as well as. The contents of some tricarboxylic acid (TCA) cycle-related organic acids were higher in the UVR-deprived group. Lipidomic analysis indicated that UVR deprivation resulted in the accumulation of monogalactosyldiacylglycerol (MGDG), digalactosyldiacylglycerol (DGDG), sulfoquinovosyldiacylglycerol (SQDG), diacylglycerylcarboxyhydroxymethylcholine (DGCC), diacylglyceryl-N,N,N-trimethylhomoserine (DGTS), and lyso-lipids, while triacylglycerol (TAG) was decreased. Consistent with these results, the transcriptomic data showed that the expressions of some key genes involved in the TCA cycle and the photosynthesis pathways were clearly induced by UVR deprivation. Besides, the down-regulation of diacylglycerol O-acyltransferases (DGAT) and the up-regulation of TAG lipase collectively resulted in the lower accumulation of TAG, which was consistent with the metabolomic data. Taken together, the decline of I. galbana in summer could be explained by the disorder of a series of biological processes caused by UVR, especially the damage to photosynthesis, the slowdown of TCA cycle, and the disturbance of lipid metabolism. This study allowed us to better understand the responses of I. galbana to UVR stress and provided useful information for the cultivation of I. galbana in summer, greatly expanding our current knowledge on the genetic information of I. galbana.

Spatial and temporal structure of phytoplankton in 2014-2016 in the Poddabie area on the southern Baltic Sea

In the Baltic Sea, there can be observed seasonal changes of the phytoplankton structure during which the species composition, abundance and phytoplankton biomass change. However, the spatial and temporal variability of individual phytoplankton groups is not the same in all the regions of the Baltic. The only research (and available studies) of phytoplankton in these shallow central sea basin zones is conducted by Institute of Meteorology and Water Management (IMWM) as part of the HELCOM Baltic Sea Monitoring at station P16, which is located closest to the studied area. Therefore, in the years 2014-2016 phytoplankton seasonality studies were carried out, which allowed to supplement data in the area of the central coast of the south Baltic [61]. Based on the above literature, the aim of this study was to determine the temporal and spatial structure and to examine the species composition of phytoplankton occurrence and biodiversity in the Poddabie region from November 2014 till September 2016. The following article presents the results obtained at 3 measuring stations (P1, P2 and P3) in the area of Poddabie. These results confirm typical changes of phytoplankton on 3 measurement stations depending on the season of the year. The collected data for this article is the second part of the three monographs on the area on the central coast of the southern Baltic. It show the exact results of the species composition and seasonal changes of phytoplankton in the Poddabie region. The average values of phytoplankton abundance and biomass were typical for this sort of coastal waters and there were no significant species differences between these stations. Comparing the results obtained in this study with the data from the IMWM annual reports for the last decade, it can be noticed that the volumes and fluctuations of total biomass and phytoplankton abundance in the three analysed areas are in line with trends typical for the South Baltic coastal area

Seasonal variability of phytoplankton in river Słupia of the southern Baltic Sea

In the Baltic Sea, there can be observed seasonal variations in the structure of phytoplankton. These organisms are particularly sensitive to changes in different environmental parameters. The consequence of these changes is cyclical repeated every year fluctuation of the species composition, their abundance and biomass of phytoplankton. The spatial and temporal variability of individual phytoplankton groups is not the same in different regions of the Baltic Sea, and this is why the study was conducted in the area of the central Baltic coast, since in that particular region data on phytoplankton is not available. One of the main goals was to determine the temporal and spatial structure of the occurrence of phytoplankton, as well as to study biodiversity in the area of the estuary of the Slupia river in southern Baltic for the period between November 2014 and September 2016. The results of the research confirm typical changes of phytoplankton in three studied areas depending on the given season. The average values of phytoplankton abundance and biomass were typical for this kind of coastal waters and there were no significant species differences between these stations. The only research (and available studies) on phytoplankton in central sea basin areas is being conducted by Institute of Meteorology and Water Management (IMWM) as part of the HELCOM Baltic Sea Monitoring at station P16, which is the closest location to the studied area. When comparing the results obtained in this study to the data from the IMWM annual reports for the last decade, it can be noticed that the size and fluctuations of total biomass and phytoplankton abundance in the three studied areas are typical for the coastal region of the South Baltic.

Dynamics of earthworm species at different depths of orchard soil receiving organic or chemical fertilizer amendments

We investigated the dynamics of different earthworm species through the soil profile, which had received short-term amendments of either organic or inorganic fertilizer in an orchard during the spring of 2016. Earthworm populations were sampled at two consecutive depths of soil on 20 and 60 days after addition of fertilizers. The dominant earthworm species were Eisenia fetida (Savigny, 1826), Dendrobaena veneta (Rosa, 1886), Dendrobaena hortensis (Michaelsen, 1890), Lumbricus terrestris (Linnaeus, 1758) and Aporrectodea longa (Ude, 1885). Seven different types of fertilizers including Urea, Ammonium sulfate (AS), Diammonium phosphate (DAP), Solupotas, NPK (15-5-25), (NPK+OM) and organic manure (OM) as experimental treatments were studied. Fluctuations in earthworm numbers and biomass were attributed to changes in time and depth of sampling, in addition to the types of fertilizers. The results of the means comparison showed that on the 20th day, at 0-20 cm soil depth, E. fetida species abundance was decreased significantly in AS and Urea treatments compared to the control plot (p˂0.05). We highlighted that from epigeic group, D. hortensis species had a better chance to survive and its population in AS treatment was more than that of Urea treatment. Results also showed that the anecic L. terrestris , had a greater tolerance to chemical fertilizers compared to the A. Longa species. The results of this study outline more clear horizons in managing the use of chemical fertilizers while simultaneously maintaining the biodiversity of soil organisms.

Seasonal variation and taxonomic composition of mesozooplankton in the southern Black Sea (off Sinop) between 2005 and 2009

The monthly and long-term fluctuations of mesozooplankton abundance, biomass, and taxonomic composition in the Sinop inner harbor (southern Black Sea) between 2005 and 2009 are presented in the present study. In total, 31 mesozooplankton taxa were identified during the study. The recorded average mesozooplankton abundance and biomass were 34,323 ± 7580 ind. m$^{-2}$ and 1208 ± 460 mg m$^{-2}$ in 2005, 95,063 ± 31,434 ind m$^{-2}$ and 1787 ± 604 mg m$^{-2}$ in 2006, 97,626 ± 12,141 ind m$^{-2}$ and 1034 ± 20 mg m$^{-2}$ in 2007, 91,918 ± 10,476 ind m$^{-2}$ and 775 ± 121 mg m$^{-2}$ in 2008, and 146,918 ± 19,671 ind m$^{-2}$ and 1955 ± 437 mg m$^{-2}$ in 2009, respectively. The highest abundance values of mesozooplankton were encountered in March 2006 (299,110 ind m$^{-2}$) with the contribution of Copepoda nauplii (167,000 ind m$^{-2}$) particularly. Meanwhile, the mesozooplankton biomass was highest in October 2005 (5852 mg m$^{-2}$), due to Parasagitta setosa (3695 mg m$^{-2}$). The heterotrophic dinoflagellate Noctiluca scintillans was a major component of plankton samples in the Sinop region, presenting its highest values in April 2005. Mesozooplankton abundance values showed significant differences (except 2007-2009 and 2008-2009) during the 5-year sampling period. Since the middle of 2006, an increase in abundance, biomass, and biodiversity of mesozooplankton has been detected. Many mesozooplanktonic species/groups showed seasonality in the study (especially Cladocera species). This seasonality was determined to be based on temperature changes.

Seasonal variability of phytoplankton in the shallow waters of the southern Baltic Sea

The Baltic Sea is characterized by a seasonal variation of phytoplankton structure. These organisms are particularly sensitive to changes in various environmental parameters. Cyclic, recurring annually fluctuation of species composition, abundance and biomass of phytoplankton is a consequence of these changes. Spatial and temporal variability of particular groups of phytoplankton is not the same in different areas of the Baltic Sea. The purpose of this work was to determine the spatial and temporal distribution of phytoplankton in three chosen areas of the coastal zone of the southern Baltic Sea (Ustka, Poddąbie and Rowy) in the period of November 2014 - September 2016. Mean values of abundance and biomass of phytoplankton for the surveyed areas were typical for this type of coastal waters. In each of the surveyed areas the same dominat species in terms of the abundance and biomass were observed. A growth of diatoms was recorded only in the area of Ustka, which could have been caused by the inflow of river waters. Seasonal surveys of phytoplankton indicated that in the case of the studies regarding this parameter – taxonomic composition, abundance and biomass in the same surveyed area were similar at the three research stations (e.g. 75-80%), depending on the season of the year. On this basis, it was concluded that, whether carrying out the monitoring of phytoplankton or planned investments, the sample collection frequency had a greater significance than the number of research stations.