Phytoplankton community structure in relation to environmental factors from the New Mangalore Port waters along the southwest coast of India

Seasonal and spatial phytoplankton distribution in relation to environmental factors was investigated in New Mangalore Port, a major port along the west coast of India. A well-mixed water column characterized the non-monsoon seasons, whereas it was weakly stratified during monsoon. Water quality index (TRIX) scores indicated good water quality except during pre-monsoon (inner zone surface) and monsoon (near bottom waters). Surface abundance of tychopelagic diatoms (Paralia sulcata, Melosira nummuloides, Cylindrotheca closterium, and Nitzschia sigma) was higher during non-monsoon seasons. Certain centric diatoms, e.g., Leptocylindrus danicus, P. sulcata, and Rhizosolenia imbricata, dominated during pre-monsoon (inner zone) and positively correlated with TRIX. High Skeletonema costatum and dinoflagellate abundance during the monsoon season coincided with high nutrient concentrations. Five potential toxic and fourteen harmful/bloom forming algal species were encountered at abundances below the level that can be considered as harmful to the ecosystem. In addition to a baseline database, this study highlights the potential use of certain diatom species as indicators of hydrography and water quality for monitoring dynamic coastal marine ecosystems.     

Nutrient dynamics and seasonal variation of phytoplankton assemblages in the coastal waters of southwest Bay of Bengal

In order to understand the phytoplankton community structure and its relationship with the environmental variables in the near shore waters of Kalpakkam, east coast of India, observations were carried out during 2008–2009. Phytoplankton population was comprised of 219 species, and the density was higher during the southwest monsoon (SWM) and inter-monsoon seasons than that of north east monsoon (NEM) season. The nutrient status on a temporal and spatial scale indicated the impact of point sources carrying anthropogenic runoff. Comparison of ambient nutrient ratios with the Redfield ratio (N/P/Si?=?16:1:16) showed a clear temporal variation in the factors that regulate the phytoplankton growth. SWM and inter-monsoon season was evident to have an acute N-limitation of algal growth (~76 %) whereas P-limitation was encountered during the NEM season (~75 %). Interestingly, a sizable population of cyanobacteria (Trichodesmium erythraeum) were noticed during NEM season when there was an exponential increase in nitrogen concentration, probably due to nitrogen fixation. No significant impact of temperature on phytoplankton proliferation was observed in situ during the study period.     

Nutrient environment of red tide- infested waters off south-west coast of India

The bloom-infested waters along the southwest coast of India were assessed to bring about the probable cause related to the excessive algal production. Low nitrate and silicate concentrations were concomitant with slightly higher levels of phosphate. The silicate depletion in the bloom area is possibly an indication of community succession (diatom to dinoflagellate), since it was completely utilized by the preceding diatom blooms. The dinoflagellates in this region could have been advected from the northern regions where it was noticed during the previous months.     

秦山岛周边海域春季浮游植物群落结构特征

于2016年4月对秦山岛周边海域5个断面20个站位浮游植物进行调查,共鉴定出浮游植物5门84种,平均密度1.10×10^5个/m^3,优势类群硅藻(70种)平均密度为8.75×10^4个/m^3,甲藻9种,平均密度为8.10×10^3个/m^3;优势种主要为琼氏圆筛藻(Coscinodiscus jonesianus)(Y=0.095)、星脐圆筛藻(Coscinodiscus asteromphalus)(Y=0.087)、针状蓝纤维藻(Dactylococcopsis acicularis)(Y=0.087)、中肋骨条藻(Skeletonema costatum)(Y=0.070)、夜光藻(Noctiluca scientillans)(Y=0.058)、刚毛根管藻(Rhizosolenia setigera)(Y=0.051)等11种;多样性指数平均值为2.76,种类分布相对均匀。受沿岸4条河口淡水径流及营养元素输入影响,靠近河口的C、D断面浮游植物密度较高,琼氏圆筛藻、星脐圆筛藻、中肋骨条藻、针状蓝纤维藻等具有较高优势度,但密度较低,赤潮风险较低;各断面优势种组成存在一定更迭。     

Investigating the impacts of treated effluent discharge on coastal water health (Visakhapatnam,SW coast of Bay of Bengal,India)

The present study investigated the impacts of treated effluent discharge on physicochemical and biological properties of coastal waters from three pharmaceuticals situated along the coast of Visakhapatnam (SW Bay of Bengal). Seawater samples were collected (during the months of December 2013, March 2014 and April 2014) from different sampling locations (Chippada (CHP), Tikkavanipalem (TKP) and Nakkapalli (NKP)) at 0- and 30-m depths within 2-km radius (0.5 km = inner, 1 km = middle and 2 km?=?outer sampling circles) from the marine outfall points. Physicochemical and biological parameters, which differed significantly within the stations, were likely to be influenced by strong seasonality rather than local discharge. Dissolved oxygen variability was tightly coupled with both physical and biological processes. Phytoplankton cell density and total chlorophyll (TChla) concentrations were significantly correlated with dissolved inorganic nutrient concentrations. CHP (December) represented a diatom bloom condition where the highest concentrations of diatom cells, total chlorophyll (TChla), dissolved oxygen coupled with lower zooplankton abundance and low nutrient levels were noticed. The centric diatom, Chaetoceros sp. (>?50%) dominated the phytoplankton community. TKP (March) represented a post-diatom bloom phase with the dominance of Pseudo-nitzschia seriata; zooplankton abundance and nutrient concentrations were minimum. Conversely, NKP (April) represented a warm well-stratified heterotrophic period with maximum zooplankton and minimum phytoplankton density. Dinoflagellate abundance increased at this station. Relatively higher water temperature, salinity, inorganic nutrients coupled with very low concentrations of dissolved oxygen, TChla and pH were observed at this station. Copepods dominated the zooplankton communities in all stations and showed their highest abundance in the innermost sampling circles. Treated effluent discharge did not seem to have any significant impact at these discharge points.     

Seasonal appearance of Chlorophyceae phytoplankton bloom by river discharge off Paradeep at Orissa Coast in the Bay of Bengal

Characteristics of the monsoonal bloom of phytoplankton at Orissa Coast in the Bay of Bengal were studied through bimonthly observation from April 2001 to December 2002. Three photosynthetic pigments chlorophyll-a (Chl a), chlorophyll-b (Chl b) and carotenoid (Car) were analyzed by absorption spectroscopic method. The seasonal variation of Chl a included phytoplankton bloom in the coastal area during monsoon period. The water column integrated Chl a reached to 68 mg m(-2) at the station-1(St1), and amounted to 20 mg m(-2) at 30 km off the river mouth during August 2001. In contrast the same amount was found at 15 km off the Mahanadi river mouth during August 2002. Salinity during this period varied from 5 psu at the St1 to 27 psu at the edge of the bloom area. The total amount of river discharge in the monsoon period calculated from daily river discharge data reported by Water Resources Department in India was 84 x 10(9) m(3) during 2001 and 20 x 10(9) m(3) during 2002. Both nitrate and phosphate concentrations showed negative quadratic relationship with salinity throughout the observation period. Extrapolated nitrate and phosphate concentration discharge from the Mahanadi river were 10.8 and 4 microg-at l(-1), respectively. Microscopic identification revealed dominance of fluvial Chlorophyceae and diatoms during the monsoon period showing influence of the freshwater discharge.     

Spatio-temporal variation in physicochemical properties of coastal waters off Kalpakkam, southeast coast of India, during summer, pre-monsoon and post-monsoon period

Seasonal observations on water-quality parameters and chlorophyll-a in the coastal waters off Kalpakkam, southeast coast of India, was carried out covering an area of about 30 km(2) to find out the variations in physicochemical properties during a monsoonal cycle of the year. Most of the parameters exhibited a significant spatial and seasonal variation. It revealed that the coastal water was significantly influenced by freshwater input from the nearby backwaters during North-east monsoon and post-monsoon periods. A marginal increase in pH from coast towards offshore was noticed during the observation. Relatively low salinity values were observed during pre and post monsoon when compared to summer. Bottom water was found to be highly turbid during summer and pre-monsoon conditions when compared to surface. This could be attributed to the strong northerly wind and northward current prior to the onset of southwest monsoon. N, P and Si based nutrients are relatively high in their concentration in the bottom water. Nitrate was significantly high during post-monsoon and contributed greatly towards total nitrogen as evident from the statistical correlation. Ammonia concentration was relatively high in the bottom samples during all the seasons except on a few occasions during post-monsoon. In general, phosphate and total phosphorous values remained low and particularly so in the surface water. Higher silicate concentration was observed in the bottom water, and there was a reducing trend towards offshore. High chlorophyll-a values were observed during summer and surface water was found to have higher pigment concentrations as compared to the bottom. Results show that phosphate acts as the limiting factor for phytoplankton production particularly during post-monsoon period whereas; none of the nutrients were found to be limiting the phytoplankton growth during other seasons.     

Monsoon-induced changes in the size-fractionated phytoplankton biomass and production rate in the estuarine and coastal waters of southwest coast of India

Changes in the autotrophic pico- (0.2–2 μm), nano- (2–20 μm), and microplankton (>20 μm) biomass (chlorophyll a) and primary production were measured in the estuarine and coastal waters off Cochin, southwest coast of India during the onset and establishment of a monsoon. During this period, the estuary was dominated by nutrient-rich freshwater, whereas the coastal waters were characterized with higher salinity values (>30 psu) and less nutrients. The average surface chlorophyll a concentrations and primary production rates were higher in the estuary (average 13.7 mg m^???3 and 432 mgC m^???3 day^???1) as compared to the coastal waters (5.3 mg m^???3 and 224 mgC m^???3 day^???1). The nanoplankton community formed the major fraction of chlorophyll a and primary production, both in the estuary (average 85 ± SD 8.3% and 81.2 ± SD 3.2%) and the coastal waters (average 73.2 ± SD 17.2% and 81.9 ± 15.7%). Nanoplankton had the maximum photosynthetic efficiency in the coastal waters (average 4.8 ± SD 3.9 mgC mgChl a m^???3 h^???1), whereas in the estuary, the microplankton had higher photosynthetic efficiency (average 7.4 ± 7 mgC mgChl a m^???3 h^???1). The heavy cloud cover and increased water column turbidity not only limit the growth of large-sized phytoplankton in the Cochin estuary and coastal waters but also support the proliferation of nanoplankton community during the monsoon season, even though large variation in nanoplankton chlorophyll a and production exists between these two areas.     

Different hydrodynamic processes regulated on water quality (nutrients,dissolved oxygen,and phytoplankton biomass) in three contrasting waters of Hong Kong

The subtropical Hong Kong (HK) waters are located at the eastern side of the Pearl River Estuary. Monthly changes of water quality, including nutrients, dissolved oxygen (DO), and phytoplankton biomass (Chl-a) were routinely investigated in 2003 by the Hong Kong Environmental Protection Department in three contrasting waters of HK with different prevailing hydrodynamic processes. The western, eastern, and southern waters were mainly dominated by nutrient-replete Pearl River discharge, the nutrient-poor coastal/shelf oceanic waters, and mixtures of estuarine and coastal seawater and sewage effluent of Hong Kong, respectively. Acting in response, the water quality in these three contrasting areas showed apparently spatial–temporal variation pattern. Nutrients usually decreased along western waters to eastern waters. In the dry season, the water column was strongly mixed by monsoon winds and tidal currents, which resulted in relatively low Chl-a (<5 μg l^?1) and high bottom DO (>4 mg l^?1), suggesting that mixing enhanced the buffering capacity of eutrophication in HK waters. However, in the wet season, surface Chl-a was generally >10 μg l^?1 in southern waters in summer due to halocline and thermohaline stratification, adequate nutrients, and light availability. Although summer hypoxia (DO <2 mg l^?1) was episodically observed near sewage effluent site and in southern waters induced by vertical stratification, the eutrophication impacts in HK waters were not as severe as expected owing to P limitation and short water residence time in the wet season.     

Variations in some environmental characteristics including C and N stable isotopic composition of suspended organic matter in the Mandovi estuary

Chemical and isotopic (??¹³C and ??¹⁵N) investigation of the Mandovi estuary along the Indian west coast affected strongly by the seasonal monsoon cycle was carried out. The Mandovi estuary is a major waterway for Goa and extensively used for transportation of iron and manganese ore. In addition, with large population centers as well as agricultural fields located on its shores, the estuary is assumed to have been influenced by human activities. Measurements of chemical and isotopic parameters made in the lower part of the estuary during the southwest (SW) monsoon and post-monsoon seasons reveal distinct changes, and it is observed that despite considerable enrichment of macronutrients during the SW monsoon, productivity of the estuary (phytoplankton biomass), as inferred from the chlorophyll-a content, is not as high as expected. This is due to occurrences of high turbidity and cloud cover that limits photosynthetic productivity. The isotopic characterization (C and N isotopes) of suspended organic matter produced/transported during the monsoon and post-monsoon seasons of year 2007 provides a baseline dataset for future isotopic studies in such type of tropical estuaries.     

Seasonal variation in physicochemical properties of coastal waters of Kalpakkam, east coast of India with special emphasis on nutrients

A study pertaining to the seasonal variation in physicochemical properties of the coastal waters was carried out at Kalpakkam coast for a period of 1 year (February 2006 to January 2007). It revealed that the coastal water was significantly influenced by freshwater input during North East (NE) monsoon and post-monsoon periods. Concentration of all the nutrients and dissolved oxygen (DO) was relatively high during the NE monsoon, whereas, salinity and chlorophyll-a (chl-a) were at their minimum level during this period. Phytoplankton production peak was observed in summer during which a typical marine condition prevailed. The present observed values of nitrate, phosphate, silicate, and turbidity are significantly high (five to ten times) compared to that of the pre-Tsunami period from this coast. Relatively low DO and chl-a concentration was noticed during the post-Tsunami period. A notable feature of this study is that though nutrient concentration in the coastal waters during post-Tsunami period has increased significantly, turbidity, the most single dominating factor, was found to adversely affect the phytoplankton production during post-Tsunami period as reflected by relatively low chl-a concentration. Thus, the post-Tsunami period may result in a change in coastal biodiversity pattern concomitant with change in coastal water quality.     

Temporal variability of macrofauna from a disturbed habitat in Zuari estuary, west coast of India

Natural disturbances along with human interference make the tropical estuaries amongst the most disturbed areas globally. In spite of this, information on the seasonal variability of macrofauna from tropical estuaries is few. Temporal variability of macrofaunal community from Mormugao Bay, Zuari estuary, on the west coast of India was examined from 2003 to 2004 at seven stations. Environmental variability was assessed through physicochemical parameters of water and sediment. The changes in macrobenthic community were assessed using abundance, biomass and species diversity indices. The environmental parameters showed a significant seasonal variation influenced by monsoonal changes. The changes in the environmental conditions brought about variation in the macrobenthic community. Macrofaunal abundance, biomass and species diversity were the highest during post-monsoon influenced by recruitment. In monsoon, the macrobenthic community was dominated by polychaetes (92.17%), whereas bivalves dominated during the post-monsoon (57.7%). The macrofauna showed drastic decline during the stable pre-monsoon season, a period when the highest abundance of fauna is observed in the tropical estuary. Therefore, the macrobenthic community in the area did not follow the seasonal trend generally observed in a tropical estuary. Further, the community during pre-monsoon season was dominated by the opportunistic polychaete species indicating a possible influence of harbour activities in structuring the benthic community of the area.     

Nutrient ratios and the complex structure of phytoplankton communities in a highly turbid estuary of Southeast Asia

Phytoplankton diversity and abundance in estuarine systems are controlled by many factors. Salinity, turbidity, and inorganic nutrient concentrations and their respective ratios have all been proposed as principal factors that structure phytoplankton diversity and influence the emergence of potentially toxic species. Although much work has been conducted on temperate estuaries, less is known about how phytoplankton diversity is controlled in tropical, monsoonal systems that are subject to large, seasonal shifts in hydrology and to rapidly changing land use. Here, we present the results of an investigation into the factors controlling phytoplankton species composition and distribution in a tropical, monsoonal estuary (Bach Dang estuary, North Vietnam). A total of 245 taxa, 89 genera from six algal divisions were observed. Bacillariophyceae were the most diverse group contributing to 51.4 % of the microalgal assemblage, followed by Dinophyceae (29.8 %), Chlorophyceae (10.2 %), Cyanophyceae (3.7 %), Euglenophyceae (3.7 %) and Dictyochophyceae (1.2 %). The phytoplankton community was structured by inorganic nutrient ratios (DSi:DIP and DIN:DIP) as well as by salinity and turbidity. Evidence of a decrease in phytoplankton diversity concomitant with an increase in abundance and dominance of certain species (e.g., Skeletonema costatum) and the appearance of some potentially toxic species over the last two decades was also found. These changes in phytoplankton diversity are probably due to a combination of land use change resulting in changes in nutrient ratios and concentrations and global change as both rainfall and temperature have increased over the last two decades. It is therefore probable in the future that phytoplankton diversity will continue to change, potentially favoring the emergence of toxic species in this system.     

舟山近岸海域赤潮优势种中肋骨条藻的生长模型

中肋骨条藻是舟山近岸海域的赤潮优势种,常有大小不等的中肋骨条藻赤潮发生.本文采用多元线性回归模拟春秋两季非赤潮期中肋骨条藻的生长趋势,以探讨影响此种藻类生长的重要因子.结果表明,春季影响中肋骨条藻生长的重要因子包括盐度、无机氮、悬浮物、水温和pH;秋季影响中肋骨条藻生长的重要因子包括溶解氧、活性磷酸盐、悬浮物、硅酸盐、COD和盐度.并与前人的研究结果相比较,从而发现赤潮期和非赤潮期共同的或不同的影响骨条藻生长的因素.     

2015—2018年海州湾及邻近海域浮游植物群落结构特征

根据2015—2018年春、夏季海州湾及邻近海域8个航次的调查资料,对该海域浮游植物种类组成、优势种、丰度及多样性进行了调查,应用相关性分析和典范对应分析(CCA)研究了环境因子对海州湾浮游植物群落结构的影响,共发现浮游植物96种,其中硅藻80种。中肋骨条藻(Skeletonema costatum)在各航次均是第一优势种。调查海域浮游植物丰度为4.20×103~7952.00×103个/L,平均值为504.54×103个/L。平均Shannon-Wiener(H’)多样性指数为2.66,2018年夏季航次最低仅1.52,2015年春季航次最高为3.73。多样性基本呈春季高夏季低的趋势。Pearson相关性分析显示,水温、活性磷酸盐及化学需氧量与浮游植物群落结构关系密切。典范对应分析则表明,海州湾春季优势物种主要受水温、溶解氧和盐度的影响,而夏季则受多种因子的综合影响。近年来海州湾浮游植物多样性整体呈缓慢下降趋势可能受紫菜大规模养殖的影响。     

Assessment of flood-induced changes of phytoplankton along a river–floodplain system using the morpho-functional approach

In this research, we aimed to find out how the differences in hydrological connectivity between the main river channel and adjacent floodplain influence the changes in phytoplankton community structure along a river–floodplain system. The research was performed in the River Danube floodplain (Croatian river section) in the period 2008–2009 characterised by different flooding pattern on an annual time scale. By utilising the morpho-functional approach and multivariate analyses, the flood-derived structural changes of phytoplankton were analysed. The lake stability during the isolation phase triggered the specific pattern of morpho-functional groups (MFG) which were characterised by cyanobacterial species achieving very high biomass. Adversely, the high water turbulence in the lake during the frequent and extreme flooding led to evident similarity between lake and river assemblages. Besides different diatom species (groups of small and large centrics and pennates), which are the most abundant representatives in the river phytoplankton, many other groups such as cryptophytes and colonial phytomonads appeared to indicate altered conditions in the floodplain driven by flooding. Having different functional properties, small centric diatom taxa sorted to only one MFG cannot clearly reflect environmental changes that are shown by the species-level pattern. Disadvantages in using the MFG approach highlight that it is still necessary to combine it with taxonomical approach in monitoring of phytoplankton in the river–floodplain ecosystems.     

Microplankton bloom in a brackish water lagoon of Terengganu

Increased primary plankton productivity was observed in a brackish water lagoon of Terengganu during the study period between January 1988 to December 1988. The lagoon is also the site for the fish cage culture activities of sea bass during the study period. An examination of water quality at the sampling stations during the study period indicated that both the organic and inorganic nutrients were high during the pre-monsoon period. The source of the nutrient in the lagoon was believed to be derived from the agro-based industrial effluents, fertilisers from paddy fields as well as untreated human and animal wastes. This coincided with the peak production of plankton in the surface waters of the brackish water lagoon. During this period both cultured and indigenous fish species were seen to suffer from oxygen asphyxiation (suffocation due to lack of oxygen). The primary productivity values ranged from 9 to 22 g/L/h during the peak period while the microplankton species were composed of diatom, flagellates and dinoflagellates. Reduction in the primary productivity values were obtained with reduction in sallinity, specially during the peak monsoon months (November to March) corresponding to the Northeast monsoon period.     

Seasonal variability of chlorophyll-a and oceanographic conditions in Sabah waters in relation to Asian monsoon—a remote sensing study

A study was conducted to investigate the influence of Asian monsoon on chlorophyll-a (Chl-a) content in Sabah waters and to identify the related oceanographic conditions that caused phytoplankton blooms at the eastern and western coasts of Sabah, Malaysia. A series of remote sensing measurements including surface Chl-a, sea surface temperature, sea surface height anomaly, wind speed, wind stress curl, and Ekman pumping were analyzed to study the oceanographic conditions that lead to large-scale nutrients enrichment in the surface layer. The results showed that the Chl-a content increased at the northwest coast from December to April due to strong northeasterly wind and coastal upwelling in Kota Kinabalu water. The southwest coast (Labuan water) maintained high concentrations throughout the year due to the effect of Padas River discharge during the rainy season and the changing direction of Baram River plume during the northeast monsoon (NEM). However, with the continuous supply of nutrients from the upwelling area, the high Chl-a batches were maintained at the offshore water off Labuan for a longer time during NEM. On the other side, the northeast coast illustrated a high Chl-a in Sandakan water during NEM, whereas the northern tip off Kudat did not show a pronounced change throughout the year. The southeast coast (Tawau water) was highly influenced by the direction of the surface water transport between the Sulu and Sulawesi Seas and the prevailing surface currents. The study demonstrates the presence of seasonal phytoplankton blooms in Sabah waters which will aid in forecasting the possible biological response and could further assist in marine resource managements.     

A comparative study on mesozooplankton abundance and diversity between a protected and an unprotected coastal area of Andaman Islands

The study was carried out to understand the variability in phytoplankton production (Chlorophyll a) and mesozooplankton diversity from two different shallow coastal regions of south Andaman viz. Port Blair Bay (PBB), the only real urban area among the islands and Mahatma Gandhi Marine National Park, a Marine Protected Area (MPA) at Wandoor. Seasonal sampling was carried out during the Northeast monsoon (NEM—November 2005), Intermonsoon (IM—April 2006), and Southwest monsoon (SWM—August 2006). Significant (P?<?0.05) seasonal variation was observed in the environmental variables at both the regions. Higher average chlorophyll a (Chl. a) and mesozooplankton standing stock were observed at PBB compared to MPA, but the seasonal variation observed was marginal at both the study areas. Chl. a showed a steep increasing gradient from outer to the inner regions of the PBB. The number of zooplankton taxa recorded at both areas was quite similar, but marked differences were noticed in their relative contribution to the total abundance. Eventhough the Copepoda dominated at both the areas, the non-copepod taxa differed significantly between the regions. Dominance of carnivores such as siphonophores and chaetognaths were noticed at PBB, while filter feeders such as appendicularians and decapod larvae were more abundant at MPA. A total of 20 and 21 copepod families was recorded from PBB and MPA, respectively. Eleven species of chaetognaths were observed as common at both areas. Larval decapods were found to be predominant at MPA with 20 families; whereas, at PBB, only 12 families were recorded. In the light of the recent reports on various changes occurring in the coastal waters of the Andaman Islands, it is suspected that the difference in Chl. a as well as the mesozooplankton standing stock and community structure observed between the two study areas may be related to the various anthropogenic events influencing the coastal waters.     

Phytoplankton distribution across the southeast Adriatic continental and shelf slope to the west of Albania (spring aspect)

We present the first insight to the oceanography of the southeastern Adriatic Sea, where coastal water influenced by Albanian rivers comes into contact with the inflowing oligotrophic Eastern Adriatic Current (Ionian Surface Water and Levantine Intermediate Water). A distinct plankton distribution was observed on each side of the shelf break hydrographic boundary in May 2009, during gradual warming of the surface waters. The prochlorophytes accumulated along the nutricline above the shelf and continental slope. The phosphorus limited inshore waters were dominated by a small diatom Chaetoceros circinalis, dinoflagellates, cryptophytes, autotrophic picoplankton, and heterotrophic nanoplankton. The offshore surface layer was characterized by bigger nanoplankton (coccolithophorids, green flagellates). Low nutrient concentrations influence relatively low productivity not only above the Albanian shelf but also further to the north along the Montenegrine and Croatian coastal Adriatic Sea.