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- Predicting zooplankton response to environmental changes in a temperate estuarine ecosystemPublication . Marques, Sónia Cotrim; Azeiteiro, Ulisses Miranda; Leandro, Sérgio Miguel; Queiroga, Henrique; Primo, Ana Ligia; Martinho, Filipe; Viegas, Ivan; Pardal, Miguel ÂngeloA novel strategy that allows to predict the responses of zooplanktonic species to environmental conditions in an estuarine temperate ecosystem (Mondego estuary) is presented. It uses 12 indicator species from the zooplanktonic Mondego database (102 species) that are common members of the different habitats, characterized by their specific hydrological conditions. Indicator-species analysis (ISA) was used to define and describe which species were typical of each of the five sampling stations in a 4-year study (2003–2006). First, a canonical correspondence analysis (CCA) was carried out to objectively identify the species-habitat affinity based on the relationship between species, stations and environmental data. Response curves for each of the zooplanktonic species, generated by univariate logistic regression on each of the independent variables temperature and salinity, were generally in agreement with the descriptive statistics concerning the occurrence of those species in this particular estuarine ecosystem. Species-specific models that predict probability of occurrence relative to environmental parameters like salinity, water temperature, turbidity, chlorophyll a, total suspended solids and dissolved oxygen were then developed for the zooplanktonic species. The multiple logistic models used contained between 1 and 3 significant parameters and the percentage correctly predicted was moderate to high, ranging from 62 to 95%. The predictive accuracy of the model was assured by direct comparison of model predictions with the observed occurrence of species obtained in 2006 (validation) and from data collected in the early 2000s in another Portuguese estuary - Ria de Aveiro (Canal de Mira), a complex mesotidal shallow coastal lagoon. The regression logistic model here defined, correctly suggested that the distribution of zooplankton species was mainly dependent on salinity and water temperature. The logistic regression proved to be a useful approach for predicting the occurrence of species under varying environmental conditions at a local scale. Therefore, this model can be considered of reasonable application (and should be tested in other estuarine systems) due to its ability to predict the occurrence of individual zooplanktonic species associated with habitat changes.
- Contrasting links between growth and survival in the early life stages of two flatfish speciesPublication . Primo, Ana Ligia; Vaz, Ana Catarina; Crespo, Daniel; Costa, Filipe; Pardal, Miguel; Martinho, FilipeUnderstanding the causes of variation in recruitment of marine fishes has been a central goal over the last century. However, the relationship between year class strength and larval growth and survival is poorly known for most species. The main goal of this study was to investigate the relationships between larval traits and year class strength of two flatfish species in an nursery estuary. We examined the effects of the variation in the early life characteristics (pelagic larval growth, pelagic larval duration, size-at-hatching and size-at-settlement) on post-settlement survival of flounder Platichthys flesus and common sole Solea solea in the Mondego estuary (Portugal) over a 5-year period (2011–2015). The two flatfish species showed distinct larval traits variation during the study period, mainly related with location of the spawning ground and intrinsic biologic patterns. Flounder was able to delay metamorphosis while gathering energy and/or waiting for suitable environmental cues from estuarine origins while sole take advantage of better environmental conditions due to a later hatching. Early fast growth were strongly related with subsequent growth, affecting larval survival. Both growth and larval traits variation during the studied period were strongly related with temperature. This study highlights the importance of early growth for fish survival and contributes with key information on fish early life stages that will support a better management of fish stocks.
- Surf zone zooplankton communities from the west coast of the Iberian Peninsula: influence of season, substrate type and environmental factorsPublication . Guerreiro, Milene Alexandra; Marques, Sónia Cotrim; Martinho, Filipe; Azeiteiro, Ulisses Miranda; Pardal, Miguel Ângelo; Primo, Ana LígiaStudies on surf zone zooplankton biodiversity and population dynamics processes remain scarce in comparison to other coastal areas. In this work, we analysed the seasonal (winter/summer) variability of the surf zone zooplankton assemblage structure and copepod biomass of distinct areas with different substrate types (sandy beaches/rocky shores) at the west coast of the Iberian Peninsula (Portugal). Cypris of Cirripedia and Acartia clausi prevailed during summer at both areas. In the winter, Paracalanus parvus and Temora longicornis were the most abundant species at sandy beaches, while Harpacticoida n.id.1 and Euterpina acutifrons dominated at rocky shores. Copepod biomass was higher during the winter and in sandy beaches. Zooplankton showed distinct community structure according to season and substrate type, with Harpacticoids and cirripeds being the main responsible for seasonal differences, while fish eggs and harpacticoids were mainly responsible for differences among substrates. Surf zone assemblages were influenced by temperature, chlorophyll a and local hydrodynamics, which reflects species seasonal reproduction and drift in the water column.