Biogeochemical fluxes of iron from rainwater,rivers and sewage to a Galician Ria (NW Iberian Peninsula). Natural versus anthropogenic contributions

The total iron (TFe) concentrations in five rivers to a Galician Ria (averages 1.0–4.5 μM) was within the pristine range, but in rainwater it was higher (17 μM). TFe values of small sewage treatment plants (STP) ranged between 3 and 4 μM, whereas in the largest was 11 μM. Particulate iron in rivers was five times more abundant than dissolved iron, except in the Lagares where it was 20 times higher, but in the STDs the dissolved/particulate coefficients varied from 0.1 to 1.1 and in the rainwater it was lower than 0.4. Equations of water flow versus iron flux were obtained to quantify the iron contribution from the freshwater sources to the Vigo Ria. It receives annually 490 tons of iron (6% in dissolved form) and 90% of this comes from industries focused on metal processes. The contaminated Lagares River accounts for the main input of TFe (327 t a⁻¹), followed by rainwater (78 t a⁻¹), the Oitavén River (28 t a⁻¹) and Vigo STP (33 t a⁻¹). Anthropogenic activities have increased the amount of iron flowing into the Ria by roughly ten times and this could upset the biogeochemical cycle in similar coastal systems.     

SHORT-TIME SCALE DEVELOPMENT OF A GYMNODINIUM CATENATUM POPULATION IN THE RIA DE VIGO (NW SPAIN)1

Wind direction and fresh water runoff determine the circulation pattern of the Ría de Vigo (NW Spain), which in turn influence the selection and distribution of its phytoplankton populations. Coastal winds with a south–southwesterly component reverse the positive estuarine circulation in the Ría, causing an off-shore to in-shore flow of surface waters and, consequently, the outflow of inner waters via deeper layers. We found that this reversal imposed a selective force on the phytoplankton population: diatoms, which could not counteract the sinking movement of the surface waters, were diminished, while dinoflagellates remained in the water column. From the end of September to the beginning of October 1993, an accumulation of Gymnodimium catenatum Graham was observed coinciding with an intrusion of coastal water induced by westerly winds which provoked a reversal in the circulation of the Ría. The slow reestablishment of the positive estuarine circulation pattern, which was due to a weak coastal upwelling and considerable fresh water runoff, allowed the population of G. catenatum to flourish.     

Modelling the influence of nutrient loads on Portuguese estuaries

The effects of implementing Directive 91/271/EEC of 21 May 1991 (Waste Water Treatment Plan Directive) and Directive 91/676/EEC of 12 December (Nitrates Directive) are analysed in 7 Portuguese estuaries (Minho, Lima, Douro, Mondego, Tagus, Sado and Guadiana) and two coastal lagoons (Ria de Aveiro and Ria Formosa), with a modelling approach. MOHID Water Modelling System was used to perform simulations with three nitrogen load scenarios for each system: a reference scenario, a 50% nitrate removal by agriculture scenario and another with a 100% nutrients removal by waste water treatment plants (WWTP). It is shown that the interaction between hydrodynamic and ecological processes is an important feature to study trophic problems in estuaries. Ecological processes such as primary production only occur inside the system if the residence time of water is high enough to enable organismal activity and if the adequate conditions are found (e.g. light, nutrients, temperature). From the model results it is possible to conclude: (i) in systems with short residence time a reduction in nutrient load will only produce a decrease in nutrient transit and will not affect the system’s global ecological status (e.g. Douro Estuary); (ii) in systems with long residence time the effects will range from significant, when primary production is mostly limited by nutrients (e.g. Ria de Aveiro), to non-significant, when primary production in the system is light-limited (e.g. Tagus Estuary).     

Influence of salt marsh on bacterial activity in two estuaries with different hydrodynamic characteristics (Ria de Aveiro and Tagus Estuary)

The influence of salt marsh on estuarine bacterioplankton was investigated in two estuaries with different hydrodynamic characteristics (Ria de Aveiro and Tagus Estuary). In the Ria de Aveiro, bacteria in the flood water overlying the marsh were two times more abundant and five to six times more active than in the main channel. In the Tagus Estuary, bacterial abundance was similar in flooding and channel water, but bacterial activity was up to two times higher in the main channel. The two salt marshes have distinct influences on estuarine bacterioplankton abundance and activity. In the Ria de Aveiro, salt marsh enhanced estuarine bacterial communities, increasing their size and stimulating their activity. By contrast, the salt marsh in the Tagus Estuary does not seem to increase the bacterial abundance and production in the channel water. These distinct influences may be explained by the hydrodynamic characteristics of the salt marshes, which were confirmed by the hydrodynamic model implemented for both systems.     

Impacts of bottom and suspended cultures of mussels <Emphasis Type="Italic">Mytilus</Emphasis> spp. on the surrounding sedimentary environment and macrobenthic biodiversity

The aim of this study was to quantify the effect of bottom and suspended mussel cultures, cultured in different physical environments, on the sedimentary environmental conditions and thereby the biodiversity structure of the associated macrofaunal community. We compared two bottom cultures (Limfjorden: microtidal, wind-driven; Oosterschelde: macrotidal) and one suspended culture (Ria de Vigo in an upwelling coastal region). The sedimentary environmental conditions (mud fraction, POC, PON, phosphorus content, chl a breakdown products) were significantly elevated underneath and surrounding bottom and suspended cultures compared to culture-free sediments that were nearby and hydrodynamically similar. The relative change in environmental conditions was more pronounced in the Oosterschelde compared to Limfjorden, most likely due to differences in hydrodynamic forcing and characteristics of the mussel bed. The effect of the suspended cultures in Ria de Vigo on the surrounding sediments was influenced by local topographic and hydrodynamic conditions. The impact of mussels on the benthic community due to biodeposition was clearly seen in the community structure. The species composition changed from species which are typically present in sandy environments to more small opportunistic species, which are typically present in organically enriched sediments. The impact of bottom cultures on the benthic community due to changes in the habitat under the presence of mussels was positive, especially in the Oosterschelde where an increase in the number of epibenthic species was seen. The influence of bottom cultures on the sedimentary environment and on the macrobenthic community seems to be very local. Within the mussel site in Limfjorden, differences were detected between sites where none or almost no mussels were present with sites where mussels were very abundant.     

中国主要入海河流河口集水区划分与分类

采用GIS技术开展中国主要入海河流的流域边界及其汇水单元、河口集水区的划分及其分类。基于ArcGIS水文分析模块划分出15条入海河流的汇水单元,并通过5种不同汇水单元面积等级的划分来表达各入海河流汇水单元的详细程度;划分的流域面积与相关文献资料对比偏差在10%以内;在流域与汇水单元划分的基础上,基于感潮河段的数据收集,确定出88个中国主要入海河流的河口集水区。通过建立分类指标体系,采用聚类分析方法,划分出5类河口:第一类EDA主要分布在环渤海地区、山东半岛和广东沿海;第二类EDA主要分布在长江口和杭州湾周围;第三类EDA主要分布在江苏北部沿海和辽东半岛;第四类包括山东江苏交界处沿海、江苏南部沿海;第五类主要分布在福建浙江沿海、珠江口、长江口、海河口附近、辽河河口附近,并利用快速生物评价法验证河口分类的合理性。研究成果可为进一步开展我国近海河口和海域营养盐基准制订与生态分区提供基础空间数据与方法借鉴。     

Tracing the late Holocene evolution of the NW Iberian upwelling system

This work analyses data from the OMEX core KSGX 40 (164-cm long) collected in the Galicia Mud Deposit, from the NW Iberian outer continental shelf, off the Ria de Vigo (North Spain). Sediment grain-size and benthic foraminifera distribution patterns indicate a number of substantial changes in sedimentation and also food/oxygen availability to the benthic ecosystem during the last ∼4.8 ka cal BP. Cluster analysis (Q-mode and R-mode) based on the most abundant taxa was used to recognize similarities within the data set. Three main clusters were established by Q-mode cluster analysis. The species distribution pattern of two of these three clusters is clearly related with changes in texture of the sediments. Textural data and benthic foraminifera proxies suggest that between ∼4.8 and 2.2 ka cal BP there was a period of higher hydrodynamism, with more energetic oceanic currents associated with shelf mixed waters. The period since ∼2.2 ka cal BP until present was characterized by generally lower bottom energetic conditions and by a supply of finer sediment, which was richer in organic matter leading to more eutrophic conditions in the benthic environment, mainly between ∼2.2 and 1.2 ka cal BP and since ∼0.5 ka cal BP until the present. Eutrophication was probably determined by strong water column stratified conditions and by coastal upwelling-dominated depositional intervals and/or by higher lateral flux of organic carbon. Since the upwelling increasing periods are in general due the intensification of northerly winds, both most productive upwelling-dominated periods may be attributed to climatic/oceanographic induced changes during the Sub-Atlantic climate. Small sea levels oscillations also should contribute to these results. Eutrophication since the end of Little Ice Age may be related to human influence in coastal areas.     

Distribution of common octopus and common squid paralarvae in a wind-driven upwelling area (Ria of Vigo, northwestern Spain)

The variation of paralarval abundance in a region subjectedto wind-driven upwelling (Ria of Vigo, northwestern Spain) wasstudied. Research cruises were undertaken during the favourableupwelling season (May to October) in 2000 and 2001. Each cruiseincluded biological and hydrographic sampling and consistedof five stations in waters located to the east and west of theCies Islands. A total of 221 paralarvae of Octopodidae and Loliginidaewere collected over the 12-month study period. During 2000,higher abundance of paralarvae was observed in July, Septemberand October for Loligo vulgaris and Octopus vulgaris. In 2001,abundance of both species was higher in May and also in Septemberfor O. vulgaris. The mantle length of the paralarvae variedfrom 1.25 to 2.25 mm and from 1.00 to 4.90 mm within the O.vulgaris and L. vulgaris individuals, respectively. The presence/absenceof upwelling modulates the abundance and spatial distributionof loliginid and octopod paralarvae. The relationship betweenthe distribution and movement of these paralarvae in the Riaof Vigo seems to follow the circulation system defined for thisarea; when the upwelling extends its influence inside the Ria,the paralarvae are transported to the inner part in a west—eastdirection.     

Application of watershed analyses and ecosystem modeling to investigate land–water nutrient coupling processes in the Guadalupe Estuary, Texas

Estuarine nutrient enrichment is thought to be controlled by land use patterns in coastal watersheds. Hence, the objective of this work was to conduct a watershed analysis in two adjacent river basins with different land use characteristics to determine their influence on estuarine ecosystem response in the Guadalupe Estuary, Texas, U.S.A. All data sources for this study were available electronically on the Internet; the data were mined, managed, analyzed and transformed to simulate the estuarine ecosystem response to watershed-derived nutrient loads. Between 1992 and 2001, developed land use/land cover increased the most while forest cover decreased the most in both basins. Two hydrologic units nearest the coast were responsible for the greatest change in land cover. Nutrient concentrations and loads were significantly higher in the San Antonio River Basin than in the Guadalupe River Basin. Both river basins exhibited the highest flows ever recorded in 1992, however the magnitude of difference in loads between the two coastal hydrologic units for a wet and dry year was much greater in the Guadalupe River Basin (GRB) than in the San Antonio River Basin (SARB); this difference supports the concept that the GRB is a nonpoint source dominated system and SARB is a point source dominated system. There was a strong correlation between developed land use and nutrient concentrations in river water; the GRB had less developed land use and lower nutrient concentrations while the SARB had more developed land use and higher nutrient concentrations. Estuarine ecosystem response differed in the timing, duration and magnitude of DIN, phytoplankton and zooplankton when nitrogen loads from the Lower Guadalupe River were used as opposed to the Lower San Antonio. The two basins studied differ in their fundamental characteristics, i.e. precipitation, flow, human population density, etc., resulting in different drivers of nitrogen loading, point sources in the San Antonio River Basin and nonpoint sources in the Guadalupe River Basin, therefore, differing estuarine ecosystem responses.     

Crab and mollusc shell drilling by Octopus vulgaris (Mollusca: Cephalopoda) in the Ria de Vigo (north-west Spain)

Octopus vulgaris living in the Ria de Vigo, north-west Spain, sometimes drills a cavity in the carapace of crabs and shells of molluscs. These holes have features with the same characteristics as those made in molluscs by O. vulgaris and in crabs by Eledone cirrhosa when isolated in aquaria. This is the first report of drilling the carapace of crabs by Octopus vulgaris .     

Cephalopod paralarvae and upwelling conditions off Galician waters (NW Spain)

A total of 103 cephalopod paralarvae were sampled during June 1995 in Galician waters (NW Spain). Samples were taken with Bongo nets of 300 and 500 m mesh size at 48 sampling stations along 10 transverse transects ranging from 80 to 600 m water depth. Paralarvae of loliginid squid were most abundant (40%). The Rhynchoteuthion paralarvae of ommastrephid squid accounted for 25%, whereas sepiolids comprised 23% of the total sample. Octopods were scarce, at only 6.6%. Other cephalopod families accounted for 5%. Sizes of paralarvae ranged from 1.0 to 7.1 mm mantle length. Temperature and salinity distribution showed the presence of an intense upwelling during the survey period. The sampling data obtained before and during the presence of upwelled water off Rias of Pontevedra and Vigo (southern zone) showed that paralarval cephalopod abundance and distribution were closely related to the upwelled Eastern North-Atlantic Central Water (ENACW).      

The effects of temperature, growth medium and darkness on excystment and growth of the toxic dinoflagellate Gymnodinium catenatum from northwest Spain

The chain-forming dinoflagellate Gynmodinium catenatum Grahamcauses recurrent outbreaks of paralytic shellfish poisoning(PSP) in the Galician Rias Bajas (northwest Spain). A sedimentsurvey in Ria de Vigo in April 1986 indicated that the highestconcentrations of cysts of this species were located in themiddle sections of the ria, with maximum abundance of 310 cystscm^–3. The effects of temperature, growth medium compositionand irradiance on the germination of laboratory-produced restingcysts were investigated. Newly formed cysts required very littletime for maturation, as excystment was possible within 2 weeksof encystment. Growth media did not affect germination success.In contrast, the excystment rate was retarded signifiantly indarkness. Germination was also strongly affected by temperature,with {small tilde}75% excystment success at 22–28°Cand little or no germination below 11°C after 1 month ofincubation. In culture, the optimum growth rate of vegetativecells was between 22 and 28°C, the highest rate being 0.53divisions day^–1 at 24°C. Growth did not occur at temperatures< 11°C or >30°C. These results are important withrespect to the different hypotheses proposed to explain theinitiation of G.catenatum blooms in the Galician Rias Bajasand Northern Portugal. The pattern of G.catenatum bloom developmentalong this coast has been related to seasonal upwelling in thearea, with major blooms occurring during the autumn as warmeroffshore surface water is transported towards the coast whenupwelling relaxes. The landward transport of established offshorepopulations of G.catenatum with the warm surface layer remainsa viable explanation for the observed blooms within the rias,but alternatively, our data suggest that cysts within the riascan provide the inoculum population at times conducive to growthand bloom formation. Even though newly formed G.catenatum cystshave a very short maturation time and can germinate in darknessacross a wide temperature range, bloom development will be significantonly during the late summer and early autumn, since in othermonths light levels at the sediment surface and temperaturesthroughout the water column are too low for significant germinationor growth.     

Food of the cuttlefish Sepia officinalis and S. elegans in the Ria de Vigo (NW Spain) (Mollusca: Cephalopoda)

A study of the diet of Sepia officinalis and S. elegans in the Ria de Vigo has shown that crustaceans are the most abundant prey in both species, followed by fish. Changes in the food composition of both species occur with growth. The type of prey eaten by the two sexes of these species is very similar. The possibility of trophic competition between juveniles of S. qficinalis and S. elegans is discussed.     

Molecular Detection of <Emphasis Type="Italic">Xenostrobus securis</Emphasis> and <Emphasis Type="Italic">Mytillus Galloprovincialis</Emphasis> Larvae in Galician Coast (Spain)

The mussel species Xenostrobus securis from New Zealand was detected in the Spanish coast recently, in the mouth of the Verdugo River into the Vigo Ria. In view of the great importance of the farm mussel sector in this region, the presence of this alien species greatly concerned producers and administration authorities, because of its potential medium- or long-term effects on the autochthonous species, Mytilus galloprovincialis, an important marine resource widely exploited in this location. The goal of this study was to develop a DNA-based technique to identify X. securis and M. galloprovincialis larvae in plankton samples, which would allow monitoring for the presence of X. securis in different points of the Vigo Ria. The techniques used were simplex and multiplex polymerase chain reaction (PCR), restriction fragment length polymorphism (RFLP), and fragment analysis. The application of this system to planktonic samples could be an effective means to assess the presence of the alien species, allowing monitoring if its dispersion is increasing, or on the contrary, if its distribution is restricted to the mouth of the Verdugo River, where X. securis was first detected. In addition, the application of this system at different times could be useful to assess the presence of larvae of these two species in the plankton.     

Accuracy in the estimation of quantitative minimal area from the diversity/area curve

The problem of representativity is fundamental in ecological studies. A qualitative minimal area that gives a good representation of species pool [C.M. Bouderesque, Methodes d'etude qualitative et quantitative du benthos (en particulier du phytobenthos), Tethys 3(1) (1971) 79] can be discerned from a quantitative minimal area which reflects the structural complexity of community [F.X. Niell, Sobre la biologia de Ascophyllum nosodum (L.) Le Jolis en Galicia, Invest. Pesq. 43 (1979) 501]. This suggests that the populational diversity can be considered as the value of the horizontal asymptote corresponding to the curve sample diversity/biomass [F.X. Niell, Les applications de l'index de Shannon a l'etude de la vegetation interdidale, Soc. Phycol. Fr. Bull. 19 (1974) 238]. In this study we develop a expression to determine minimal areas and use it to obtain certain information about the community structure based on diversity/area curve graphs. This expression is based on the functional relationship between the expected value of the diversity and the sample size used to estimate it. In order to establish the quality of the estimation process, we obtained the confidence intervals as a particularization of the functional (h-phi)-entropies proposed in [M. Salicru, M.L. Menendez, D. Morales, L. Pardo, Asymptotic distribution of (h,phi)-entropies, Commun. Stat. (Theory Methods) 22 (7) (1993) 2015]. As an example used to demonstrate the possibilities of this method, and only for illustrative purposes, data about a study on the rocky intertidal seawed populations in the Ria of Vigo (N.W. Spain) are analyzed [F.X. Niell, Estudios sobre la estructura, dinamica y produccion del Fitobentos intermareal (Facies rocosa) de la Ria de Vigo. Ph.D. Mem. University of Barcelona, Barcelona, 1979].     

Coupling between Marine Plankton and Freshwater Flow in the Plumes off a Small Estuary

Freshwater discharge from rivers is a powerful forcing agent in coastal ecosystems. It not only generates strong ecological effects in estuaries, but also drives the dynamics of nearshore marine waters where prominent river plumes form biogeochemical hot spots in coastal seas worldwide. Large plumes from major rivers exert important controls on pelagic processes. The majority of estuaries are smaller, however, and the importance of the smaller plumes they generate is unknown. We measured the degree of coupling between freshwater flow and inshore zooplankton in such a plume from a subtropical estuary on the east coast of Australia. Flow regimes encompassed long periods of low freshwater input, punctuated by pulsed freshets that initiated the formation of buoyant, lower‐salinity plumes in the nearshore marine zone. Plumes stimulated phytoplankton biomass in the receiving waters, and ultimately changes in zooplankton assemblages. Zooplankton responded strongly to river discharge: (1) in the absence of substantial freshwater flows and plumes, zooplankton was broadly similar in density and biomass across the estuarine‐marine gradient; (2) freshets that generated significant plumes strongly modified hydrological conditions and lowered zooplankton in the estuarine and nearshore waters, and (3) after the initial freshet, zooplankton in the residual plume was at a higher density in nearshore than shelf waters. We demonstrate that coupling between riverine and coastal pelagic systems operates in small plumes, but that there is substantial temporal variance linked to fluctuations in freshwater delivery. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

River flows and estuarine ecosystems: Implications for coastal fisheries from a review and a case study of the Logan River,southeast Queensland

River discharge has long been recognized as one of the factors that contributes to the high productivity of estuaries. Although there is little evidence that river inputs of terrestrial carbon make a direct contribution to coastal food webs, such exported nutrients may stimulate in situ production in estuaries and thus enhance the survivorship and growth of fish and crustaceans in these systems. Furthermore, fluctuations in salinity and turbidity may influence the extent of available habitat for fish and crustaceans and therefore their distribution and/or catchability. Despite these potential links between flow and the secondary production of estuaries and coastal waters, there is still a common perception that ‘water going to sea is wasted’ and a continuing trend to regulate the flow of rivers. We review the evidence for links between river flow and the productivity of estuarine/coastal fisheries, drawing on a case study of the Logan River in southeast Queensland, and explore the potential mechanisms for these linkages. Our research, and that of others, confirms that high river discharge can have a strong positive effect on the production of commercial and recreational coastal fisheries. It also shows that the seasonal pattern of flow is equally, if not more important, than the magnitude of flow. River regulation is likely to have a dramatic effect on the production of coastal fisheries and, given the current pressures for water resource development, this is an important avenue for future research and evaluation.     

The mussel <Emphasis Type="Italic">Xenostrobus securis</Emphasis>: a well-established alien invader in the Ria de Vigo (Spain,NE Atlantic)

Biological and habitat characterization of the non-indigenous invasive species Xenostrobus securis was undertaken in the Ria de Vigo. This study included genetic identification of mussel samples collected from introduced and endemic areas, and the assessment of mussel size, population abundance, geographic distribution, pathological condition, and sediment composition of substrata type. The mussel had a marked patchy distribution, being more abundant in brackish sites with fine sediments and high organic matter content. Pathological analysis revealed that X. securis does not play any role as vector for introducing allochthonous pathogens in the Ria de Vigo. Nevertheless, depending on its invasiveness potential, the mussel could be a key host favouring spreading and epizootic outbreaks of marteliosis which is known to be harmful for local bivalve populations. Phylogenetic analyses of the COI gene placed all the resulting sequences in a clade within the genus Xenostrobus and its phylogeny congruent with an Australian/Pacific origin. The COI tree suggests two historical introductions in European waters. One of these invasions seems to have started in Galicia, moving from there towards Italy and France, while the geographical spread of the second invasion cannot be deciphered, although the Australian/Pacific origin of this invasion seems very possible. The 18S network is congruent with one invasion starting in Galicia or in Italy, as the Australian haplotype is closely related to the haplotype found in these areas. Several hypotheses accounting for the colonization history of this species in Galician waters are discussed.     

Use of otolith chemistry to examine patterns of diadromy in the threatened Australian grayling Prototroctes maraena

Otolith chemical analyses (proton-induced X-ray emission and laser ablation inductively coupled plasma mass spectrometry) were used to examine patterns of diadromy in Australian grayling Prototroctes maraena collected from three rivers in south-eastern Australia. Concentrations of Sr:Ca and Ba:Ca were measured in the sagittal otoliths of 25 fish and in water samples collected on two occasions from multiple sites within freshwater, estuarine and marine reaches of the rivers. The results provide evidence of marine residency during the juvenile phase, with high Sr:Ca and low Ba:Ca in the inner region of the otoliths that were consistent across all three rivers. This general pattern was apparent for all individuals examined, suggesting that diadromous migration may be an obligate aspect of the life history. The chemical signatures of the outer regions of the otoliths were distinct between the three rivers, whilst there was no difference in the inner regions of the otoliths. This suggests that juveniles from different rivers may reside in a relatively homogenous chemical environment, such as the sea, and populations in coastal Victorian rivers may share a common marine recruitment source.     

Habitat quality of estuarine nursery grounds: Integrating non-biological indicators and multilevel biological responses in Solea senegalensis

Estuaries are highly valuable ecosystems that provide various goods and services to society, such as food provision and supporting nursery habitats for various aquatic species. Estuarine habitat quality assessment is thus critical in managing both ecological and economic value. In this work, various biological and non-biological indicators of habitat quality in estuarine nursery areas were determined, encompassing local environmental conditions, chemical contamination, anthropogenic pressures, juvenile Solea senegalensis condition, biomarkers response to contamination and juvenile density. The various indicators provided an integrated view on habitat quality and their responses were broadly concordant. Nursery quality assessment based on anthropogenic pressure indicators and fish biomarker responses were very similar, signaling nursery areas with higher anthropogenic pressure in Tejo and Ria de Aveiro estuaries. Yet, favorable environmental conditions across all sites could have contributed to lessen the potential hazardous biological effects of exposure to anthropogenic stressors, resulting in soles’ fairly good condition and generally high juvenile density. Nevertheless, a mismatch between high juvenile density and high estuarine contribution to adult coastal populations was observed in areas with higher anthropogenic pressures. Although a causal relationship cannot be established, the results emphasize the need to fully understand how the estuarine period spent in estuaries and local processes determine the quantity and quality of juveniles exported to marine adult populations, which is critical to achieve the full potential of the fish production service of estuaries and coastal stock replenishment.