Low Tide Periods Research Articles

Brachyuran crab diversity and abundance patterns in the mangroves of Cameroon

Brachyuran crabs are the most important group of mangroves epifauna. They operate relevant ecological roles in terms of structure and function in mangrove ecosystems. The study aims to assess crab diversity and the patterns of their distribution for biodiversity documentation. The survey was carried out in mangrove forests of the Cameroon coastline. Investigations were randomly carried out on 17 degraded mangrove areas where Rhizophora stands dominated. Crabs were collected during the period of low tide, during day and night times in the 4 × 4 m2 quadrant plots delimited inside each belt zonation throughout transects. In total, 27 crab morphospecies were recorded with global sampling effort equals to 87.5%. Eleven morphospecies were recorded for the first time in Cameroon. Sesarmid crabs were most represented (10 species) with abundant taxa (72.9% of individuals). Crab community has low species richness and diversity indices (d=0.004; H′=3.3±0.1; J′=0.8). Hill evenness are close to 1, confirms that one species (Guinearma kamermani) tends to dominate the whole community. Armases elegans, Chiromantes buettikoferi, Goniopsis pelii, Metagrapsus curvatus, Guinearma alberti, G.huzardi and G. kamermani were the common species in the study areas. The Center mangrove stands appeared most diverse (E(Sn=401)=18±1.1species), followed by the South (E(Sn=401)=16±0.5species) and the North (E(Sn=401)=11±0.0species). Species abundance is typically distributed as in linear log series (Motomura model) corresponding to the disturbed environments. The lack of conservation strategies in the management of mangrove forests in Cameroon might lead to the disappearance of these ecosystem properties and its relevant components.

Benthic primary production in emerged intertidal habitats provides resilience to high water column turbidity

Increasing inputs of terrigenous sediments from anthropic land use change elevates water column turbidity, reducing light availability to benthic primary producers that sustain estuarine food webs. For intertidal habitats, photosynthesis during low tide periods of emergence may provide resilience against this temporally displaced stressor, yet the significance of low tide production (PP) has largely been overlooked. Emerged and submerged benthic PP was measured in adjacent seagrass (Zostera muelleri) and microphytobenthos-dominated (sandflat) soft-sediment habitats at three locations encompassing a turbidity gradient. Light and dark benthic incubation chambers were used to measure the flux of CO2 across emerged sediments, and dissolved oxygen across submerged sediments to derive net (NPP) and gross (GPP) PP. Seagrass NPP and GPP exceeded sandflat habitats (by 3–8 times) at low turbidity sites during submergence and at all sites during emergence (p < 0.01), whereas habitat differences were absent (p > 0.1) in turbid locations. Emerged NPP and GPP were higher (2–16 times) than submerged in all habitats and locations (p < 0.01). When standardised by mean incident photosynthetically active radiation (PAR), the difference between emerged and submerged seagrass PP increased with site turbidity, from 2 to 26 times greater. In a global context of increasing inputs of terrigenous sediment to estuaries, emerged PP may be crucial for providing resilience against benthic productivity losses in highly turbid environments.

NOTAS SOBRE PÉROLAS PRODUZIDAS POR Anomalocardia brasiliana (BIVALVIA, VENERIDAE) (GMELIN, 1791) EM UM ESTUÁRIO DO CEARÁ

A espécie Anomalocardia brasiliana (Gmelin,1791), pertencente à família Veneridae, possui ampla distribuição geográfica e pode ser encontrada ao longo de todo litoral brasileiro. São organismos filtradores, dióicos de fecundação externa e estão adaptados a uma grande variedade de hábitats. O presente estudo registra a ocorrência de pérolas em venerídeos da espécie A. brasiliana coletados em uma área do estuário do Rio Acaraú, próximo a praia de Volta do Rio. As coletas foram realizadas mensalmente de janeiro/2015 a dezembro/2015, nos períodos de maré baixa de sizígia. Para as quais utilizou-se o método dos quadrados aleatórios, com um quadrado de PVC de 50cm x 50cm e escavando-se o sedimento a uma profundidade de 5 cm. Foram coletados e examinados um total de 9152 exemplares, o comprimento da concha dos mesmos variou entre 2,67 mm a 33,21 mm. Do total analisado foram extraídas seis pequenas pérolas de formato esferoide demonstrando baixa incidência em relação ao total amostrado. O registro da formação de pérolas em A. brasiliana no nordeste brasileiro desperta a necessidade de novos estudos para elucidação da produção de pérolas, em especial sobre os efeitos das variáveis ambientais neste processo.

Seroepidemiology of arbovirus in communities living under the influence of the lake of a hydroelectric dam in Brazil

Abstract Introduction The arbovirus proposes an important problem of public health in Brazil, especially in the Amazon, due to its capacity to cause outbreaks with high levels of morbidity-mortality in humans as well as in animals. Objective This paper had the objective to estimate the prevalence of antibodies to arbovirus in communities that live under the influence of the artificial lake of UHE Tucuruí in the State of Pará, Brazil. Method The analytical transversal study has selected 657 blood serum samples of individuals over 18, both genders, residents at the Sustainable Development Reserves (SDR) in the region of the lake of UHE Tucuruí. The epidemiological information has been registered in an instrument especially designed for such a study and the blood samples were collected in two periods of high and low tide of the lake. The blood serum tests were performed by the method of hemagglutination inhibition (HI). Results The results revealed a prevalence of positive antibodies to arbovirus of 85.0%, being 84.1% related to Flavivirus (vaccine strain of YFV), 25.5% related to Alphavirus and 34.6% to Bunyavirus. The results of serum prevalence to arbovirus between the periods of high tide and low tide have revealed significance amongst the Alphavirus, not observed in the other families. Conclusion In general, the data from this paper have suggested that the anthropoid actions on the environment of the lake have become determinant factors for the prevalence of arboviral antibodies.

A Validation of Observed Meteotsunami in the West Coast of Sri Lanka with European Centre of Medium Range Weather Forecasts (ECMWF) Modelled Data

Metetsunamis are local regional events originating from perturbation of water levels by the impulse of particularly pressure drop in a disturbed atmospheric weather system and amplified to a destructive Tsunami wave with the combined effect of resonance. For the preliminary investigation a Meteotsunami event was analysed for one minute’s frequency data collected in situ sea level measuring station established in Colombo, Sri Lanka under the authority of National Aquatic Resources Research and Development Agency (NARA) with the supervision of Intergovernmental Oceanographic Commission (IOC). The contribution of disturbed weather system was analysed using wind speed (ms-1), atmospheric pressure (hPa) 10 min frequent reading from the Meteorological Department of Sri Lanka and weather station established under the bilateral project of University of Notre dame and NARA. The observed Meteotsunami event was validated using gridded modelled data (12.5 km resolution) obtained from the European Centre of Medium Range Weather Forecasts (ECMWF) and analysed using 6 hourly frequent atmospheric pressure (hPa) data, U and V at wind data at 10 m height and significant wave height. For the identification of Meteotsunami events, observed tide gauge readings were analysed in few different steps. The tidal constituents were quantified using harmonic analysis to obtained astronomical effect removed sea level variation and filtered to isolate Meteotsunami events using math lab software.According to the in situ observation data the atmospheric pressure gradient was recorded as 1008-1001 milibar hours while the modelled value dropped from 1009 to 1002 milibar hours. The observed wind speed was increased from 14.21 to 31.90 mph within 4 hours of time period and ECMWF wind speed increased from 11.02 to 19.94 mph with positive deviation. The observed wave height of Metiotsunami event was >0.3 m while model derived wave height was 0.6 m during the low tide period of the day. According to the threshold criterion suggested by Monserrat for classifying Meteotsunami, resulted wave amplitude of observation data exceeded 4 x σ, where σ is standard deviation of astronomical effect removed residual sea level time series. Further studies are required for the investigation of propagation mechanism with amplifying through the bays with the resonance effects. Further high frequency data are insufficient for the investigation of correlation with synoptic scale meteorological event.The ECMWF model is highly recommended for the prediction of disturbed atmospheric system and related ocean based extreme event forecast for prevention of ocean, atmospheric hazards and mitigation of vulnerability with the effect of global change giving real value of lives in the earth. Keywords: Sea level, Meteotsunami, Tsunami, Atmospheric, Resonance

Nghiên cứu sự biến động sinh khối phiêu sinh thực vật và hàm lượng ôxy hòa tan để quản lý đàn cá trên kênh Nhiêu Lộc - Thị Nghè, Thành phố Hồ Chí Minh

The study was conducted during one-year cycle, with six sampling periods in January, March, July, September and November 2015 to identify the phytoplankton and dissolved oxyen (DO) fluctuations at the Nhieu Loc - Thi Nghe (NL-TN) canal in spatial, temporal and tidal scales, thereby proposing solutions to manage the fish stock in the canal. The NL-TN canal is devided into three sections including downstream, midstream and upstream, with nine sampling stations. The collected samples represented the highest and lowest tide periods of the month. The results showed that the phytoplankton biomass reached highest value in upstream (5,2-6,1 gDW/m3) and lowest in downstream (4,4-4,9 gDW/m3); however, there is no correlation between high biomass phytoplankton and low DO in early morning in spatial scale. In terms of temporal aspect, phytoplankton biomass reached the highest in July (6.9 gDW/m3) and the lowest in September (3.5 gDW/m3); however, there is no correlation between phytoplankton and DO biomass over time. Therefore, the monitoring of phytoplankton biomass with the frequency of 2 months/time is not effective in predicting correlative fluctuations of phytoplankton indicator with DO deficiency for fish stock management. Considering tidal fluctuations, high and low tide levels had significant influence on the annual average phytoplankton biomass difference. Considering the DO aspect, DO shows the lowest level in the early morning of May at the low tide period, which coincides with the high mortality of fish stock in the canal at the beginning of the rainy season, posing a requirement for DO monitoring and management at the risky times with DO deficiency for fish stock management.

Assessing the Organic Pollution and Aquaculture Activity of Surface water at Shatt-Al-Arab Estuary Southern of Iraq

Surface water samples were collected monthly from December, 2012 to November, 2013 at the middle part of Shatt Al-Arab Estuary at Basrah city during the low tide period to assess the organic pollution status using the Organic Pollution Index (OPI), and the aquaculture activities using Minimum Operator Concept (MOC). Results of biological oxygen demand (BOD5), ammonium, nitrite and orthophosphate were used to calculate OPI, while dissolved oxygen (DO), total phosphate and turbidity were used to calculate MOC. Results showed that OPI values range from 4.5 - 4.75 referred to weak organic–non organic pollution status. On the other hand, the water of Shatt Al-Arab Estuary can be considered as medium–excellent water for aquaculture activity according to the MOC range (66.67 - 93.33). Keywords: Estuary, Surface water, Organic Pollution Index, Aquaculture activity, Minimum Operator Concept

Effects of tidal cycles on shorebird distribution and foraging behaviour in a coastal tropical wetland: Insights for carrying capacity assessment

Wetland loss has driven negative effects on biodiversity by a reduction in potential available habitats, directly impacting wetland-dependent species such as migratory shorebirds. At coastal areas where tidal cycles can restrict food access, the degree to which density of foraging birds is mediated by conspecific abundance or by the available areas is crucial to understanding patterns of bird distribution and wetland carrying capacity. We used the bathymetry of two sectors modeled with two numerical matrices to determine the availability of intertidal foraging areas in relation to tidal level (spring and neap tides), and this information was used to estimate shorebird density and foraging activity throughout the low-tide cycle in a tropical coastal lagoon in northwestern Mexico. Relative to spring tides, an 80% reduction in available foraging areas occurred during neap tides. Overall shorebird abundance was significantly reduced during neap tide periods, with differences between species. Densities of shorebirds increased during neap tides, particularly in one sector, and remained similar throughout the low-tide period (i.e. 4 h) either during spring or neap tides. Time spent foraging was consistently lower during neap-tides relative to spring-tides, especially for Long-billed curlew (44% reduction), Willet (37% reduction) and Black-necked stilt (29% reduction). These decreases in foraging activity when available habitats became reduced can hamper the opportunities of migratory shorebirds to reach their daily energy requirements to survive during the non-breeding season. This study shows that when intertidal habitats are severely reduced an important fraction of shorebird populations would probably be forced to find alternative areas to forage or increase foraging time during the night. Serving an essential function as top-predators, these results can have important implications on carrying capacity assessment for shorebirds at coastal wetlands.

The density and reproductive biology of the Fiddler Crab Uca sindensis (Alcock, 1900) (Crustacea: Ocypodidae) in intertidal zone of Shatt Al-Basrah river –Khor Al-Zubair, Iraq.

The density and reproductive biology of Uca sindensis were studied inintertidal zone of Khor Al-Zubair, south of Shatt Al-Basrah river, Basrah, Iraq.The crabs were collected randomly three 0.25m2 quadrates during low tideperiods from November 2014 to October 2015. Density of crabs, sex ratio,distribution, population structure, diameter burrow, breeding season andfecundity were investigated. The results showed that crabs population fluctuatedand depended on the months of the year. Crabs density in study area was(181ind/ m2 in April 2015) and (19 ind./m2 in December 2015). The CW offemales ranged from 4 to 13.5 mm and of males from 5 to 16 mm indicatingsexual dimorphism. The relationship between Carapace width (CW) × Carapace height (CH) was positive in males and females. The equation (Log CH=Log-4.644+4.362LogCW) for males (P 0.05), however the monthly sex ratio wasdifferent from expected 1:1(χ test, P<0.05). Breeding took place during warmseason of March to October 2015. The regression analysis showed that thenumber of eggs increased linearly with the increase of carapace width (r2=0.775, n=38). It was concluded that some factors of temperature, Salinity andTOM in sediment affected at density growth and reproduction pattern in U.sindensis.

Morphometric sexual maturity and allometric growth of the crab Sesarma rectum Randall, 1840 (Crustacea: Sesarmidae) in an impacted tropical mangrove in northeast Brazil

The size at sexual maturity and the allometric growth of the semi-terrestrial crab Sesarma rectum were studied in an impacted tropical mangrove in northeast Brazil. Crabs were monthly collected during spring low-tide periods, from October 2009 through September 2010. A catch-per-unit-effort (CPUE) technique was used to sample the crab population, with two-hour sampling periods, by two people. A total of 492 crabs were obtained, being 262 males and 230 females. The specimens were measured at carapace width (CW), the left and right propodus length and height (RPL, RPH, LPL and LPH), and the gonopod length of males (GL), and abdomen width (AW) of females. In males, the inflection point was at 27.14 mm CW in the relationship between CW and the length of right propodus (LRP), considering the morphological size at the onset of maturity. Based on the relationship between CW and AW, the size at sexual maturity in females was 22.97 mm. In spite of living in an impacted area, this population attained the maturity onset at a bigger size than other localities.

Coral mortality induced by the 2015–2016 El-Niño in Indonesia: the effect of rapid sea level fall

Abstract. The 2015–2016 El-Niño and related ocean warming has generated significant coral bleaching and mortality worldwide. In Indonesia, the first signs of bleaching were reported in April 2016. However, this El Niño has impacted Indonesian coral reefs since 2015 through a different process than temperature-induced bleaching. In September 2015, altimetry data show that sea level was at its lowest in the past 12 years, affecting corals living in the bathymetric range exposed to unusual emersion. In March 2016, Bunaken Island (North Sulawesi) displayed up to 85 % mortality on reef flats dominated by Porites, Heliopora and Goniastrea corals with differential mortality rates by coral genus. Almost all reef flats showed evidence of mortality, representing 30 % of Bunaken reefs. For reef flat communities which were living at a depth close to the pre-El Niño mean low sea level, the fall induced substantial mortality likely by higher daily aerial exposure, at least during low tide periods. Altimetry data were used to map sea level fall throughout Indonesia, suggesting that similar mortality could be widespread for shallow reef flat communities, which accounts for a vast percent of the total extent of coral reefs in Indonesia. The altimetry historical records also suggest that such an event was not unique in the past two decades, therefore rapid sea level fall could be more important in the dynamics and resilience of Indonesian reef flat communities than previously thought. The clear link between mortality and sea level fall also calls for a refinement of the hierarchy of El Niño impacts and their consequences on coral reefs.

Inhibition effect of zinc in wastewater on the N2O emission from coastal loam soils

The effects of zinc (Zn) on nitrous oxide (N2O) fluxes from coastal loam soil and the abundances of soil nitrifier and denitrifier were studied in a tidal microcosm receiving livestock wastewater with different Zn levels. Soil N2O emission significantly increased due to discharge of wastewater rich in ammonia (NH4+-N) while the continuous measurements of gas flux showed a durative reduction in N2O flux by high Zn input (40mgL−1) during the low tide period. Soil inorganic nitrogen concentrations increased at the end of the experiment and even more soil NH4+-N was measured in the high-Zn-level treatment, indicating an inhibition of ammonia oxidation by Zn input. Quantitative PCR of soil amoA, narG and nirK genes encoding ammonia monooxygenase, nitrate reductase and nitrite reductase, respectively, showed that the microbial abundances involved in these metabolisms were neither affected by wastewater discharge nor Zn contamination.

Applied Heavy Metals Pollution Index (HPI) as a Water Pollution Indicator of Shatt Al-Arab River, Basrah-Iraq

Five stations were selected at the middle part of Shatt Al-Arab river to determine the monthly variation of seven eco-toxic elements (Cd +2 , Cu +2 , Fe +2 , Mn +2 , Ni +2 , Pb +2 and Zn +2 ) concentrations and their distribution as dissolved and particulate (exchangeable and residual) phases during the low tide period from December, 2012 to November, 2013. Heavy Metals Pollution Index (HPI) was applied to determine the pollution of Shatt Al-Arab water. Results showed that the concentrations of the previous metals as dissolved phase were (3.01; 2.35; 89.45; 4.48; 9.51; 43.67 and 7.58) µg/l, respectively, whereas in the exchangeable phase of particulate were (48.56; 53.22; 8968.76; 1748.58; 120.14; 271.52; 243.16) µg/g dry weight respectively and in the residual phase of particulate were (57.59; 88.68; 21571.74; 365.90; 163.39; 388.44 and 219.42) µg/g dry weight respectively. The results indicated that mean HPI values were found to be above the critical pollution index value of 100. HPI values for the presence study were ranged from 130.41 to 196.97 referred to polluted water caused by the world impermissible values of dissolved Pb, Fe and Cd.

EVALUATION OF IRAQI COASTS USING LITTORAL AND MARINE BIVALVE SHELLS

The geochemical analysis of both of Crassostrea cucullata and Chione californensis shells and hydrochemical analyses of water are carried out to study the environmental evaluation in the Iraqi coasts. Shells and water are collected during low tide period (March to August 2011), from seven different stations (Fadakia, Rass AlBishah, Khor Abdullah, Khor Shytianah, Hacham Island, Khor AlZubair and Shatt AlBasrah). The hydrochemical analyses reflect two zones of water salinity, Fadakia and Shatt AlBasrah of brackish water with TDS range (15148 – 18130 ppm), and the other marine coastal sites of saline water with TDS range (34123 – 45220 ppm). XRD of shells of Chione californensis reveals that they have two layers, an inner layer constitutes of aragonite and outer layer constitutes of calcite, while the shells of Crassostrea cucullata have only calcite layer. Water salinity increasing associate with increase of major chemical constituents of oyster shells. Mg/Ca and Sr/Ca values in the coastal line Crassostrea cucullata shells are higher than Fadakia and Shatt AlBasrah shells that may be due to increment of salinity in the coastal line compared with Fadakia and Shatt AlBasrah areas. Zn, Cu, Pb, Sr, and Cr metals in Khor Shytianah Crassostrea cucullata are higher than the other areas may attribute to higher contamination in this area. The chemical constituents of CaO%, MgO, Sr/Ca and Mg/Ca in Khor Shytianah and Hacham Island Chione californensis shells are higher than Khor Abdullan shells, this result may be indicator to higher salinity of sea water in Khor Shytianah and Hacham Island compare with the sea water of Khor Abdullah. Heavy metals (Co, Ni, Rb, Sr, Zn, Ba, Cr, Th, Mo, and Pb) in Khor Shytianah Chione californensis shells were more than the other shells may be due to high range of contamination of sea water by this metal.

Population biology and morphometric sexual maturity of the fiddler crab Uca (Uca) maracoani (Latreille, 1802) (Crustacea: Decapoda: Ocypodidae) in a semiarid tropical estuary of northeastern Brazil

The population biology and size at sexual maturity of Uca (Uca) maracoani were studied for the first time in a semi-arid tropical estuary of northeastern Brazil. A catch-per-unit-effort (CPUE) technique was used to sample the crabs, on the surface and inside burrows, for 60-min sampling periods by one person on a monthly basis during spring low tide periods from June 2013 to June 2014 in an estuary area of Baixa Grande Beach. A total of 406 crabs were obtained, of which 317 were males, 87 non-ovigerous females, and two ovigerous females. Males were larger than non-ovigerous females. The U. (U.) maracoani population presented unimodal size frequency distribution, which may reflect a continuous recruitment, with no disruption of classes and constant mortality rates, indicating a stable population. The overall sex ratio (3.5 males: 1 female) differed significantly from the expected 1:1 proportion. The major cheliped was on the right side in 45.1% of the males, as reported for other fiddler crabs populations. A total of 294 males and 89 females were used in the allometric study. The specimens were measured at carapace width (CW), the major propodus length (MPL) of males, and abdomen width (AW) of females. In males, the relationship between CW and MPL was 22.3 mm CW, which is considered the functional value at maturity. In females, the size at sexual maturity was 19.3 mm CW based on the relationship between CW and AW. The CPUE method is discussed as one of the reasons of the high sex ratio skewed towards males. This is the first account regarding population structure of U. (U.) maracoani in semi-arid tropical areas.

Ichnological evidence of Megalosaurid Dinosaurs Crossing Middle Jurassic Tidal Flats.

A new dinosaur tracksite in the Vale de Meios quarry (Serra de Aire Formation, Bathonian, Portugal)preserves more than 700 theropod tracks. They are organized in at least 80 unidirectional trackways arranged in a bimodal orientation pattern (W/NW and E/SE). Quantitative and qualitative comparisons reveal that the large tridactyl, elongated and asymmetric tracks resemble the typical Late Jurassic-Early Cretaceous Megalosauripus ichnogenus in all morphometric parameters. Few of the numerous tracks are preserved as elite tracks while the rest are preserved as different gradients of modified true tracks according to water content, erosive factors, radial fractures and internal overtrack formations. Taphonomical determinations are consistent with paleoenvironmental observations that indicate an inter-tidal flat located at the margin of a coastal barrier. The Megalosauripus tracks represent the oldest occurrence of this ichnotaxon and are attributed to large megalosaurid dinosaurs. Their occurrence in Vale de Meios tidal flat represents the unique paleoethological evidence of megalosaurids moving towards the lagoon, most likley during the low tide periods with feeding purposes.

Análise dos estudos de capacidade de carga turística para os recifes de Picãozinho, Seixas (João Pessoa-PB) e Areia Vermelha (Cabedelo-PB)

A crescente procura por atividades recreativas em ambientes naturais tem trazido à tona a necessidade do uso de ferramentas de planejamento turístico visando a realização de um turismo ordenado em que os danos causados aos locais de visitação sejam mínimos. A metodologia de capacidade de carga está relacionada à determinação do número máximo de pessoas em uma área sem que sejam provocados danos significativos ao ambiente visitado. Na Paraíba, os recifes costeiros de Picãozinho, Seixas e Areia Vermelha constituem formações recifais onde tem-se a realização de atividade turística durante o período da maré baixa quando piscinas naturais contendo uma diversidade de organismos marinhos tornam-se emersas. Os processos metodológicos envolveram levantamento bibliográfico dos estudos de capacidade de carga desenvolvidos para as três localidades durante os últimos dez anos. Neste estudo objetivamos rediscutir a eficiência de tais propostas por meio de uma análise crítica que destaque os aspectos ligados à metodologia para o desenvolvimento de um turismo sustentável. Os resultados apontaram que a determinação da capacidade de carga de uma área vem atrelada a uma grande subjetividade. Não é possível garantir que, por meio do número de usuários definido, os impactos de uma dada localidade sejam reduzidos ou eliminados. Ações de manejo em conjunto em um processo de planejamento contínuo são necessárias para um gerenciamento eficaz.

Emergence behavior of a tide pool fish Praealticus tanegasimae (Teleostei; Blenniidae) on subtropical reefs

Praealticus tanegasimae is a rockpool blenny that occurs around the higher edge of the intertidal zone in subtropical waters of the western Pacific. Terrestrial emergence from tide pools was confirmed in the blenny during daytime low tide periods on Kuchierabu-jima Island, southern Japan. They stayed in the pools, putting their heads above the water surface, and then jumped out with a tail flip. The duration for each terrestrial emergence ranged from 4 to 665 s (median 31 s), during which they never showed reproductive-related behaviors or active feeding behavior on land. The emergence behavior was often followed by hopping toward neighboring pools, and suggested that the goal of the behavior was to change pools for escape from unfavorable water conditions.

Role of sequential low-tide-period conditions on the thermal physiology of summer and winter laboratory-acclimated fingered limpets, Lottia digitalis

The rocky intertidal zone is among one of the most highly variable environments on Earth, with rapid and unpredictable changes in temperature on a daily basis. Numerous studies have investigated the thermal physiology of intertidal animals; however, few have focused on an organism’s capacity to withstand repeated heat stress during the emersion of low-tide periods and how previous exposures to sublethal increases in temperature may modulate the capacity to withstand severe heat stress. Lottia digitalis, a species of limpet ubiquitous along the Pacific coast of North America, were acclimated under ambient ocean conditions in the laboratory during the summer and winter months. Limpets were aerially exposed with or without preliminary heat exposures of varying magnitudes (15–35 °C for 2 h) the day before being challenged to a lethal temperature increase to investigate how sequential low-tide-period conditions affect upper thermal tolerance and temperature sensitivity. Limpets with a preliminary aerial exposure of 25–35 °C (summer) and 20 °C (winter) had greater upper critical thermal limits of cardiac performance as determined by final breakpoint temperature (~1.5–6 °C increase) and flatline temperature (~1–2 °C increase) than limpets with no previous exposure. The magnitude of temperature increase that conferred significant increases in thermal tolerance differed in summer and winter, reflecting seasonal differences in the thermal environment in nature. Fingered limpets’ upper thermal tolerance is plastic and likely modulated by the previous day’s low-tide exposure, demonstrating the importance of incorporating the repeated nature of stress into thermal physiology research in intertidal organisms.

Pelagic larval duration, size at settlement and coastal recruitment of the intertidal blennyLipophrys pholis

To study some early life history traits ofLipophrys pholis, 110 recruits (TL ≤ 30 mm) were collected in April and May 2013 during the low tide periods in four rocky beaches along the west (Cabo do Mundo, Peniche and Vale do Homem) and south (Olhos de Água) Portuguese coasts. Pelagic larval duration, size at settlement and age at coastal recruitment were back-calculated from the microstructure of otoliths. Pelagic larval duration estimated from micro-increment counts until the settlement marks ranged from 57 to 73 days and showed a latitudinal reduction trend from north to south. This variable seems to be related in 30% with the regional seawater temperatures probably through the direct effect on the somatic growth. Settlement sizes (~19 mm) did not show any regional differences suggesting that this is a more conservative character within species. The mean age at coastal recruitment varied between 69 and 93 days, but northern individuals were recruited at an older age. Back-calculated spawning, hatching and settlement dates appear to be unrelated to the lunar cycle forL. pholis.