In order to evaluate the seasonal responses of periphytic protozoan fauna to the antibiotic nitrofurazone at sensitive concentration, a 1-year baseline survey was carried out in Chinese coastal waters of the Yellow Sea. To assess the nitrofurazone (NFZ)-induced toxicokinetics in different season, the test protozoan samples were collected using microscope slides and exposed to the sensitive NFZ concentration of 8 mg ml−1. Differences in species composition and typical species were observed in the test organism fauna in the control and treatment among four seasons. However, the community patterns were significantly shifted under the sensitive concentration, with a part of stressed test samples significantly departed from a respected taxonomic pattern. Therefore, it is suggested that periphytic protozoan fauna may be significantly changed at the same sensitive concentration in both the species composition and community pattern, although there were significant differences in tolerant species among four seasons in marine environments.

Metal concentrations in coastal zones are a critical study subject since anthropogenic activities surrounding these zones are increasing and affecting environmental concentrations of metals. Macroalgae have been used as biomonitors since they can act as indicators of metal concentrations in the water column. Tissue samples of three abundant macroalgae species (Spyridia filamentosa, Padina mexicana and Ulva ohnoi) were collected from three sites with different anthropogenic impacts at La Paz Bay and Guaymas Bay, Mexico, during three contrasting seasons (dry, rainy and cold) in the year 2016. Tissue concentrations of iron (Fe), manganese (Mn), copper (Cu), zinc (Zn), nickel (Ni), cadmium (Cd) and lead (Pb) were determined by atomic absorption spectrophotometry. The highest concentrations were found in S. filamentosa inhabiting both bays. The highest Cd and Mn concentrations were recorded in algae from La Paz Bay, while the highest concentrations of Cu, Zn, Pb and Fe were recorded in algae from Guaymas Bay. Metal concentrations varied seasonally; the highest Fe, Cu, Zn, Ni and Pb levels were recorded in the cold season in algae from both bays. S. filamentosa concentrated more Fe, Ni, Cu, Zn and Pb, while P. mexicana and U. ohnoi showed higher Mn and Cd. Therefore, S. filamentosa proved to be the most suitable indicator of metal concentrations, followed by P. mexicana and U. ohnoi. The high metal concentrations recorded in algae from San Juan de la Costa, La Paz Bay, are related to mining activities, whereas those in algae from Guaymas Bay are related to canneries, maritime traffic and others.

Several species of neotropical felines are morphologically and ecologically similar, and are sympatric along large areas of their distribution. This requires mechanisms to allow their coexistence, such as temporal segregation of their activities. The aim of this study was to evaluate the relation between activity patterns of felines and their prey using camera trapping data and their seasonal variation in two tropical environments in south-western Mexico. Excepting Puma concolor, activity patterns for each feline species did not differ significantly between seasons nor between vegetation types. Activity patterns did not differ significantly between species of similar size: mid-sized species had high activity pattern overlaps in the medium forest while large-sized species overlapped to a lesser extent in the cloud forest. Leopardus wiedii differed from large-sized predators in its activity patterns. We recorded a relatively high temporal overlap between felines and their main prey species, particularly in the periods of maximum activity. We found no evidence of temporal segregation between the felines of the Sierra Norte region of Oaxaca and we suggest their coexistence is mediated by the selection of prey with different activity patterns.

The polychaete assemblages inhabiting the coastal waters of the Oualidia lagoon were studied during winter 2013 and summer 2013. Taxonomic composition and diversity were determined at 43 sample sites. Among the 13 species of polychaetes recorded, 10 were newly reported for Oualidia lagoon. Hediste diversicolor and Capitella sp. were the most abundant taxa in both seasons. Temperature and salinity were higher, and chl-a and OM were lower, in summer than in winter. The structure of the polychaete assemblages was characterized by forming three main clusters, either based on sampling stations or on polychaete species. These clusters were organized according to a downstream gradient, with the stations having fine sediments and a H. diversicolor assemblage in the inner lagoon being replaced by stations with medium grain-sized sediment and a Capitella sp. assemblage in the mid-lagoon, which were in turn replaced by stations having sandy sediments and assemblages dominated by Glycera alba (winter) and P. africana (summer) in the areas closer to the lagoon inlets. The shift was, in fact, from a classical, brackish, lacunar assemblage to two different, temporal aspects of a marine assemblage (close to the inlets), with a transition assemblage in between. This corresponded with a typically paralic spatial structure whose main descriptors responded to a confinement gradient. Despite the absence of a river, the organization of the polychaete assemblages closely resembled that of an estuarine system, with the tidal regime playing a major driving role.

Seasonal changes in spatial structure of biomass of submerged aquatic vegetation (SAV) and environmental variables were evaluated in Celestun Lagoon, an estuarine habitat in Mexico. Geostatistical techniques were used to evaluate spatial autocorrelation and to predict the spatial distribution by kriging. The relative contribution of 11 environmental variables in explaining the spatial structure of biomass of SAV was evaluated by canonical correspondence analysis. Spatial partitioning between species of SAV was evident: the seagrasses Halodule wrightii and Ruppia maritima dominated the seaward and central zones of the lagoon, respectively, whereas the green alga Chara fibrosa was constrained to the inner zone. The spatial structure and seasonal variability of SAV biomass were best explained by organic carbon in the sediments, salinity and total suspended solids in the water column. Analysis at different spatial scales allowed identifying the importance of spatial structure in biotic and abiotic variables of this estuarine habitat.

This study looks at the feasibility of using Ocean Acoustic Tomography for long-term monitoring of polynyas using both observations in Terra Nova Bay polynya (Ross Sea) and simulations with a range dependent, multi-layered adiabatic normal mode acoustic propagation model. The summer sound speed profile is characterized by surface values of around 1450 m s−1, a minimum of 1441 m s−1 around 50 m depth and a linear increase with a 0.016 s−1 slope. Thus, the sound propagation is apparently ducted in the near surface layer and is refracted upward below it. During winter, due to water cooling and mixing processes, the subsurface minimum disappears, the surface sound speed is about 1440 m s−1 and no near surface layer ducted propagation occurs. Because of the specificity of the Terra Nova Bay seasonal sound speed profile and to cope with both deep and shelf water applicability, the feasibility study of acoustic inversion was undertaken using normal mode Match Field Tomography instead of the more classical travel-time inversion. The results from simulations demonstrate that ocean acoustic tomography is able to reproduce quite well the vertical sound speed profile, in particular the temporal evolution of summer stratification and winter mixing processes, thus providing information on the upper layer, where direct measurements are not possible.

Marine populations are distributed heterogeneously in space and time because of the diversity of habitats and the requirements of species life cycles. Human exploitation of these resources also varies as a function of space, time and the type of fishing activities performed. These three factors determine fishing strategy at different levels of integration. The purpose of this study was to describe and analyse, with respect to different time scales, the relations between the modalities of resource exploitation and the biological or demographic characteristics of the species involved. These investigations relate to the more general task of acquiring the basic knowledge needed for spatialised management of fishing effort. A fleet of trawlers from La Rochelle, operating in the Bay of Biscay, was studied over a 15-year period (1979–1993), which led to the development of a reference resource exploitation scheme for these vessels. The degree of stability of this scheme over time was determined from landing profiles of the 18 most important species fished (94% of landings). An annual cycle for the species composition of landings was determined by multiple factor analysis. Two factors account for more than 55% of the inertia of the data. The first, of biological origin, is closely related to the breeding activity of species and associated migrations between the coast and the open sea. The second is spatial in nature, corresponding to the distribution and availability of resources according to a bathymetric gradient. This organisational scheme persisted over the first 13 years, but showed signs of change toward the end of the study period. Analysis of multi-year trends indicated four periods marked by sustained levels of landings per unit of effort for some species (decreasing for sole and wedge sole, or increasing for Norway lobster, striped red mullet, rays and the smallspotted catshark). These changes are attributable to restrictions on resource access imposed on the fleet (regulations and/or competition among the fishing gears for occupation of space), variations in the abundance of traditionally fished populations (hake, anglerfish) and changes in the professional behaviour of fishermen.

Seasonal variability in the morphology of the digestive tubules was investigated by means of a morphometric procedure in a population of Littorina littorea (Mollusca, Gastropoda) collected from the Abra estuary (Bay of Biscay, Basque Country) at four different seasons September, December, May and July). Some biometric characteristics of the winkles were recorded throughout the study period. Size parameters did not change significantly but high values of flesh condition (wet weight of flesh in mg per wet shell weight in g) were recorded in December and the lowest values in May. The reproductive state was determined using a planimetric procedure to calculate the relative tissue volume of digestive gland, gonad and storage tissue in the visceral mass. The relative volume of the digestive gland was significantly reduced in May. Gonad tissue volumes were maximal in May and minimal in September. Reserve connective tissue reached a maximum value in September. The quantitative structure of the digestive tubules was also investigated. The following five parameters were used to quantify digestive tubule morphology: mean epithelial thickness (MET), mean diverticular radius (MDR), mean luminal radius (MLR), MLR/MET ratio and MET/MDR ratio. The seasonal changes in the tissue composition of the visceral mass do not affect significantly any of these parameters. Thus, reserve storage/consumption and gamete development did not appear to affect the morphology of the digestive tubules in winkles. Reduced MET and MET/MDR values and augmented MLR/MET values were, however, observed at the breeding-spawning period. Such changes resemble a general stress response which might be related to the high metabolic cost of this phase of the reproductive cycle.