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A population of sea urchins, Paracentrotus lividus, from the central west coast of Portugal was studied to characterise their reproductive biology and possible relationships with environmental factors. An annual gametogenic cycle was found, with a broad spawning season, from May to November, according to a relatively synchronous gamete maturation process. Depending on the environmental factors (temperature, photoperiod), two separate periods could be distinguished, with more individuals maturing and spawning at the same time. When this happened, the first event evolved when temperature rose to a critical point, and the second occurred afterwards, when temperature decreased significantly. Notwithstanding, it was found that individuals matured later than previously described for other populations (e.g., north of Portugal), mostly in late spring, with a higher gonadosomatic index in May. A new classification scale was proposed for identifying the stages of P. lividus gametogenic cycle, based on new findings. It contributed to its simplification and easier comprehension. This study provides useful information for a differentiated sustainable management of P. lividus, according to local conditions. Establishing a closed harvesting season might be considered, based on the differences observed between Portuguese populations and other European ones. [ABSTRACT FROM AUTHOR]

The upstream movement of juvenile eels (median total length (TL) = 138 mm) in the Mondego River, Portugal, was analysed between January 2017 and August 2019. A total of 12,019 individuals (TL ranging from 60 to 287 mm) were counted and measured on an eel ladder at Coimbra weir, 44 km upstream from the river mouth, during their upstream movements. Although eels were counted throughout the year, a clear seasonal peak was detected in spring and late summer, with 93% of total movements occurring between April and September. No differences were found in the total length of individuals moving upstream between years. Generalised additive models, with an explained deviance of 83% and an adjusted R2 of 0.88, identified minimum water temperature as the main environmental variable explaining these movements, with a threshold of 13 °C triggering the onset of movements, and a peak between 15 and 19 °C, which corresponds to the spring and summer periods. Other predictors such as photoperiod, precipitation and river flow also contributed as explanatory variables in the model but less importantly. The present results may contribute to the management of this endangered species in the southern region of its distribution range by defining adequate temporal windows to monitor and promote the movement of juvenile European eels through obstacles to migration. [ABSTRACT FROM AUTHOR]

Background: Three-axis acceleration sensor acoustic transmitters (AccelTag) programmed to identify specific acceleration patterns associated with particular behaviours (e.g., burrowing, attack) were used to study some aspects of the ecology of the Lusitanian toadfish Halobatrachus didactylus (Bloch & Schneider 1801). The AccelTag combines the features of archival tags (records acceleration in all three directions measuring also roll-independent pitch/tilt angle and roll around the fish's axis) and acoustic transmitters. Therefore, this tag can autonomously identify and record specific signatures (i.e., behaviour patterns) of different movements transmitting autonomously and periodically the data to an acoustic biotelemetry receiver. Lusitanian toadfish is a subtropical marine teleost confined to estuaries in its northern limit of distribution due to thermal constraints. During 2010 (August and October), 24 toadfish were captured, tagged with the AccelTag and released in the Mira estuary, SW coast of Portugal, where an array of underwater automatic acoustic biotelemetry receivers was deployed. Results: Around 40% of AccelTag transmissions from tagged fish that stayed in the study area were logged by the acoustic receiver array. The Lusitanian toadfish exhibited low activity during late summer and early autumn (< 3% of time active). The tidal stage and time of day were important factors that influenced the species behaviour and activity. Increased burrowing and re-burrowing movements were registered during spring tides, while attacks prevailed on neap tides and during the night. The tidal cycle only influenced toadfish behaviour and activity in interaction with time of day, with more attacks and higher levels of activity during nocturnal high tides. Conclusions: Higher activity levels and attacks displayed by the Lusitanian toadfish during the night, at high tide periods and during Spring tides are considered to be associated with increased activity and vulnerability of its prey during these periods. The AccelTag proved to be a powerful tool to assess and monitor the activity and fine-scale behaviour of fish in situ. This technology is particularly suited for fish species with biological and ecological features similar to Lusitanian toadfish, i.e., resident species with low activity levels and behaviours with a distinct 3D acceleration signature. [ABSTRACT FROM AUTHOR]

The beach‐seine fishery is a commercial fishing activity on the Portuguese coast, with reports dating as far back as the early 15th century. The main target species of this fishery are small pelagic fish such as Atlantic chub mackerel, Atlantic horse mackerel and sardine. To identify the best conditions for fishing the target species, catches of beach seine (2007–2017) were used and generalized linear models were applied, using a binomial and gamma distributions. The logistic model explained between 36.3% and 45.7% of the catches variability; the gamma model explained 9.1% and 46.9% of the catches variability, being month and wind direction the best covariates for the occurrence and/or abundance of the three small pelagic fishes in analysis. If the effort is directed to the days that meet the conditions found for each species (sardine: between May and October, wind NW, daytime; Atlantic horse mackerel: May, NW/NE wind, 800 m from the coastline; Atlantic chub mackerel: from July to August, NW moderate wind), a reduction in bycatch and discards can be achieved. This approach can have a positive economic and social impact, since it provides information for turning fisheries more efficient. [ABSTRACT FROM AUTHOR]

Typology schemes are useful in partitioning natural spatial variability and thus helping implementing bioassessment methods. They have become widely accepted in Europe after the publication of the Water Framework Directive (WFD). The major objective of this study was to test if six Portuguese pre-defined physical stream-types (using System-B of the WFD) are concordant with macroinvertebrate assemblages collected in 31 undisturbed sites in a Portuguese river basin. A top-down (stream types defined by physical attributes) and a bottom-up approach (river classes defined by biological communities) were used. No significant differences were found in the mean number of taxa and abundance of different physical stream types and few taxa are characteristic of specific stream types. Discriminant analysis (DA) considering family-level composition revealed that all stream-types were significantly different and the cross-validation process showed that all stream-types had more than 50% of their samples correctly assigned. On the other hand, the bottom-up approach based on a correspondence analysis (CA) showed some overlap of the macroinvertebrate communities of pre-defined stream types, indicating that variations in the macroinvertebrate community structure was primarily related to altitude, mineralisation and a temporal gradient. DA cross-validation and CA results suggest that tested stream types do not account for natural temporal changes known to affect macroinvertebrate communities in this Mediterranean basin and that the WFD typology should account for these natural variations. The exclusion of natural variability could indicate impairment when it does not exist or no impairment when it does exist (type I and II statistical errors). [ABSTRACT FROM PUBLISHER]

The common sea urchin Paracentrotus lividus (Lamarck, 1816) is the most consumed echinoid in Europe. It is considered a seafood delicacy, given its high-valued gonads. In sea urchins, temperature probably represents the most important abiotic factor affecting several physiological processes and it is essential to better establish optimal reference conditions for aquaculture. In this study, four rearing temperatures (18 °C, 20 °C, 22 °C and 24 °C) were tested in wild-caught adult P. lividus , from the west coast of Portugal. The animals were fed an agar-based artificial diet, over a period of 90 days. The effect of temperature was tested in terms of test diameter and total wet weight, feed intake, gonadosomatic index (GI) and reproductive development. Thus, linear growth rate (mm month−1), daily growth rate (% day−1), total wet weight gain (mg ind.−1 day−1) and total feed intake (g day−1 ind.−1) of sea urchins were calculated at the end of the trial. Although feed intake was relatively similar between groups, the results showed a consistent response for biometric parameters regarding the different temperatures regimes. The rearing temperature of 22 °C promoted the highest test diameter (.53 mm month−1) and total wet weight (47 mg ind.−1 day−1) growth. Sea urchins from the same group (22 °C) presented the highest final GI of 9.3%, a 163.5% increase in comparison to the initial value, after the fasting period (3.5%). This temperature also promoted the highest gonad maturation levels, both in males and females. Although increasing temperatures (until 22 °C) generally produced favourable rearing results, the 24 °C regime led to lower somatic and gonadal growth, plus slower gonad maturation results. Overall, P. lividus fed with a formulated diet and reared at 20–22 °C, showed considerable somatic and gonadal growth, as well as a significant sexual maturation, which will allow to obtain developed gonads and gametes all year round. On the other hand, 18 °C promoted a slower progression in the gametogenic cycle, which may contribute to produce gonads with better organoleptic properties for human consumption. • Paracentrotus lividus was reared at four different temperatures (18, 20, 22, 24 °C). • Test diameter and total wet weight growth rates were highest at 22 °C. • Gonadal growth and maturation were highest at 22 °C, both in males and females. • Maturation was less pronounced at 18 °C, being more appropriate for human consumption. [ABSTRACT FROM AUTHOR]

The introduction of non-indigenous species (NIS) induces severe impacts on marine biodiversity and ecosystems. Macaronesia is an ecologically relevant region where several NIS were detected recently. For the first time, a standard experimental approach was designed to examine biofouling assemblages and investigate NIS across the region. In this context, sessile biofouling assemblages were examined in four recreational marinas in all the Macaronesian archipelagos from 2018 to 2020: the Azores, Madeira, Canary Islands, and Cabo Verde. We hypothesised that NIS numbers, abundance, and recruitment differed in each location due to abiotic and biotic features. From the Azores (higher latitudes) to Cabo Verde (lower latitudes), NIS recruitment and percentage cover decreased following a partial latitude gradient. The present study unveiled 25 NIS, with new records for the Azores (two cryptogenic species), Canary Islands (one NIS and two cryptogenic species), and Cabo Verde (three NIS and three cryptogenic species). The present research represents a pioneer and relevant step in advancing our current understanding of marine biological invasions in Macaronesia, employing a standard and low-cost approach., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Authors. Published by Elsevier Ltd.. All rights reserved.)