Nutrient Content and Limitation of the Phytoplankton Primary Production in the Estuary Area of the Vodopadnaya River (South Coast of Crimea)

The paper studies eutrophication of the waters of the Yalta water area caused by the Vodopadnaya River runoff and provides assessment of its influence on the characteristics of the phytoplankton primary production limitation by nutrients. The work was performed during 2020.Water samples for hydrochemical analyses were taken in fresh water of the Vodopadnaya River lower reaches and in seawater of its estuarine area. Based on the materials of observations in 2020, the paper characterizes the content of mineral nitrogen compounds (in the form of nitrites, nitrates, ammonium, and total content) and mineral phosphorus in the estuarine area of the Vodopadnaya River, which flows into the Black Sea within the city of Yalta. The influence of atmospheric precipitation on the change in the concentrations of nutrients in the waters of the mouth reach and estuarine front was determined. It was established that nutrient input with the river runoff can shift the nitrogen limitation of the phytoplankton primary production to the phosphorus one. It was shown that river runoff is one of the key factors affecting the degree of eutrophication of sea waters within the recreational zone of Yalta. This should be taken into account when developing strategies for optimizing the urban environment and recreational and tourist infrastructure of the region.

Environmental Factors Affecting the Spatiotemporal Distribution of Copepods in a Small Mesotidal Inlet and Estuary

To understand the environmental factors affecting the spatiotemporal distribution of copepods, sampling was conducted seasonally in a small mesotidal inlet and estuary located in Doam Bay of southwestern Korea. The study area was divided seasonally into two or three station groups (estuarine, mixed, and coastal) by a cluster analysis and non-metric multidimensional scaling based on copepod abundance. Acartia forticrusa, A. hudsonica, A. ohtsukai, Paracalanus parvus s. l., Pseudodiaptomus marinus, Tortanus derjugini, T. dextrilobatus, T. forcipatus, Oithona spp., and harpacticoids were important species for grouping the stations. The spatiotemporal distribution of the first two species was restricted to the estuarine area in summer and significantly correlated with temperature, salinity, and chlorophyll-a concentration. The distribution of other brackish species, such as T. derjugini and T. dextrilobatus, significantly correlated with temperature, salinity, and chlorophyll-a concentration. In contrast, A. hudsonica significantly correlated with dinoflagellate density and turbidity in winter, in addition to the abovementioned environmental factors. Acartia hudsonica also maintained a large population in the estuarine area in fall and winter, and its distribution extended across the entire bay in spring. Other coastal species occurred in all areas and did not significantly correlate with environmental factors. Therefore, brackish species in the study area may have developed seasonally different behaviors to sustain their populations.

Gauchergasilus euripedesi (Copepoda, Ergasilidae) parasitizing different species of fish from two environments in southern Brazil

The parasitic copepod Gauchergasilus euripedesi (Montú, 1980) Montú & Boxshall, 2002 was described from plankton samples and specimens found in four fish species from the estuarine area of Patos Lagoon, state of Rio Grande do Sul (RS), Brazil. Later, one different fish species was reported parasitized with G. euripedesi in the same locality. Species of Astyanax Baird & Girard, 1854 (Astyanax henseli Melo & Buckup, 2006 and Astyanax lacustris (Lütken, 1875)) and Psalidodon Eigenmann, 1911 (Psalidodon eigenmanniorum (Cope, 1894) and Psalidodon aff. fasciatus (Cuvier, 1819)) were collected in two environments (Pintada Island, municipality of Porto Alegre and Itapeva Lagoon, municipality of Terra de Areia, RS) to investigate their parasites. The copepods found in the gill arches were counted, processed, mounted in permanent slides, and photographed using light microscopy, or processed for observation in scanning electron microscopy. Specimens of P. eigenmanniorum from Pintada Island, A. lacustris and P. aff. fasciatus from Itapeva Lagoon, were parasitized by G. euripedesi, with prevalences of 29.03% (A. lacustris), 10.34% (P. eigenmanniorum), and 9.68% (P. aff. fasciatus). Measurements obtained for specimens of G. euripedesi were similar to those found in the literature, except for egg sacs which were larger in the specimens examined in the present study. In addition to being the first report of G. euripedesi parasitizing species of fish (A. lacustris, P. eigenmanniorum, and P. aff. fasciatus), the results presented here also extend the known geographic distribution of the copepod species.

Tingkat kerusakan ekosistem mangrove di Kawasan Estuari Sei Jang Kecamatan Bukit Bestari Kota Tanjungpinang, Kepulauan Riau, Indonesia

Research on the level of damage to mangrove ecosystems has been carried out in Estuarine Area Sei Jang. The purpose of this study was to determine the types of mangroves, the density and percentage of mangrove canopy cover, and the level of damage to mangrove ecosystems in the Sei Jang Estuary Area of Tanjung Pinang City. This research was conducted in March 2019. Determination of the research location using a purposive sampling method of 3 stations and using a 10 x 10 m transect for the density and percentage of mangrove canopy cover. The results found four types of mangroves namely Bruguiera gymnorhiza, Rhizophora apiculata, Rhizophora mucronata, and Ceriops tagal with density values (1.033-1.367 individu/ha) and the percentage of mangrove canopy cover with values (61.55-78.41%). For the level of damage at Station I and III are categorized (good) and Station II is categorized (Damaged).

Distribution of benthic foraminifera upstream of the Elbe Estuary (Northern Europe): ecological interactions

<p>Estuaries are transitional ecotones influenced by both marine and terrestrial (fresh) waters. For the past 200 years, estuarine environments experienced intense and rapid environmental degradations due to anthropogenic action (e.g., urban sewage, industry, aquaculture, and agricultural runoff). The distribution of benthic foraminifera in estuarine areas is the result of complex interactions between a large number of biotic and abiotic parameters. The natural stress (such as variation in salinity, sediment size, organic load) may be associated to anthropogenic stresses, enhancing the high natural variability of these areas. The objectives of the present work are to describe the specific composition of benthic foraminifera and to investigate their ecological interactions upstream of the Elbe Estuary (Germany). In this important estuarine area, there is a lack of a comprehensive investigation in terms of benthic foraminifera. So far, the ecology of living benthic foraminifera has not been studied in greater detail and it is largely unknown which species occur in this transitional area. For this purpose, a surface sampling was carried out from 24 stations along the salinity gradient of the Elbe Estuary. Living and dead foraminiferal assemblages were analyzed and the relative correlation with environmental parameters (such as salinity, pH, temperature, sediment size, organic matter) was investigated. Living assemblages are characterized by very low densities and largely dominated by “Ammonia” group. Dead assemblages are more diverse and dominated by estuarine taxa (Ammonia aomoriensis, Haynesina germanica, and Cribroelphidium selseyense). Upstream of the estuarine area, the low salinity prevents the development of living benthic foraminifera while downstream, sediment grain size seems to be a major key-factor, influencing foraminiferal distributions. This work sheds new light on benthic foraminiferal ecology and biodiversity of this important estuarine area of Northern Europe.</p>