Distribution of charophyte species in Estonian coastal water (NE Baltic Sea)

Abstract

SUMMARY: Charophytes constitute a group of macrophytes that usually inhabit soft bottoms with shallow water. They occur mostly in fresh-water environments but can also be found in brackish waters. Due to their requirement for clear water they are considered sensitive to eutrophication and therefore often used as an indicator for good water quality. The diverse structure of the Estonian coastline with its numerous sheltered bays and shallow, soft-bottom archipelago areas coupled with low salinity conditions provides an excellent habitat for charophytes. To date, seven species have been described in Estonian coastal waters, NE Baltic Sea. Last systematic investigations on charophyte distribution date back 20-30 years. During the summer of 2001 the locations where charophytes have previously been found were revisited and new sites sampled, to describe the present distribution of quantitative and qualitative parameters of charophyte species. Sampling was performed mainly by SCUBA diving; occurrence, abundance and wet weight biomass were estimated for each location. Six species of charophytes were identified. Compared to previously recorded material, no significant changes in the distribution pattern of charophytes were found. The dependence of charophyte distribution on environmental settings was tested, with depth and substrate quality explaining most of the variability in distribution. Salinity within observed range had minor influence on charophytes.Key words: Charophytes, Baltic Sea, depth distribution, salinity. RESUMEN: DISTRIBUCIÓN DE LAS ESPECIES DE CARÓFITOS EN AGUAS COSTERAS DE ESTONIA (MAR BÁLTICO NE). -Los Caró-fitos son un grupo de macrófitos que por lo general viven en fondos blandos con aguas someras. Se encuentran sobre todo en ambientes de agua continental, pero pueden hallarse asimismo en aguas salobres. Debido a su necesidad de aguas transparentes con frecuencia se les considera sensibles a la eutrofización y, por ello, suelen ser utilizados como indicadores de buena calidad del agua. La estructura variada del litoral de Estonia, con sus numerosas bahías resguardadas y áreas de archipiélagos con fondos blandos y someros, junto a condiciones de baja salinidad, proporciona un hábitat excelente para los carófitos. Hasta la fecha se han descrito siete especies de carófitos en las aguas costeras de Estonia, en el NE del mar Bál-tico. Las últimas investigaciones sistemáticas sobre la distribución de los carófitos se remontan a hace 20-30 años. Durante el verano de 2001 se volvieron a visitar las localidades en las que previamente se habían encontrado carófitos y se muestrearon nuevos emplazamientos, para describir la distribución actual de parámetros cuantitativos y cualitativos relativos a las especies de carófitos. El muestreo se realizó principalmente mediante buceo con escafandra autónoma; para cada localidad se estimaron la presencia, abundancia y biomasa en peso húmedo. Se identificaron seis especies de carófitos. Comparado con el material registrado previamente, no se descubrieron cambios importa...

Climate change induced decadal variations in hydrodynamic conditions and their influence on benthic habitats of the Estonian coastal sea

“…It appeared that due to the existence of numerous shallow bays and banks within the otherwise hydrodynamically rather active study area, there are still a number of suitable, well-sheltered and soft-bottom habitats for macrophytes. C. aspera (found in 411 locations), T. nidifica (337 locations) and Chara canescens (168 locations) are the most abundant species among the charophytes in the West Estonian coastal sea [13,16]. Altogether 7 species of Charales can be found in the Estonian coastal sea.…”

“…Potamogeton pectinatus, Zannichellia palustris and Myriophyllum spicatum) are abundant in these areas [16]. In general, the spatial distribution of charophytes is sensitive to light conditions, salinity, waves, and bottom substrate [12,13]. Species-wise, their spatial distribution reflects local hydrodynamic conditions and shifts in their occurrences and coverage may probably be used as indicators for climateinduced changes in hydrology.…”

“…The material was collected within the Estonian National Monitoring Programme (phytobenthos sub-programme) in 1995-2010, as well as during some special surveys aimed at mapping charophytes communities [13]. Altogether 8832 locations have been visited, which covers the larger part of the Estonian coasts (Fig.…”

“…In turn, salinity and temperature play an important role in recruitment dynamics of many fish species [1]. Besides, most of the macrophytes species found in the Estonian coastal waters are sensitive to salinity changes [13,16]. In addition to horizontal circulation, also occasional upwellings or changes in their occurrence statistics may have a profound impact on water column properties and productivity [8].…”

Seasonal variation in invertebrate grazing on Chara connivens and C. tomentosa in Kõiguste Bay, NE Baltic Sea

“…Charophytes often reach deeper than submerged angiosperms yet can also prevail in shallow waters (Chambers and Kalff 1985). In the Baltic Sea this group of algae inhabits sheltered coastal areas where their distribution pattern is primarily controlled by exposure, sediment type and salinity regime (Schubert and Yousef 2001a;Torn et al 2004).…”