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Fouling species display characteristics that make them suitable options for bioremediation of aquaculture effluents. We studied the potential use of two fouling species (Amphibalanus amphitrite and Saccostrea cucullata) in remediation of shrimp (Litopenaeus vannamei) farm wastewaters. Their abilities, individually and in combination, in reducing nitrogen, phosphorus, and phytoplankton (chlorophyll a) from effluents at three densities and three retention times (1, 3, 6 h) were investigated. The results showed that all treatments, specifically oysters, could effectively reduce nutrients and plankton concentrations. Oysters reduced total nitrogen, total phosphorus and chlorophyll a to 60.7%, 55.6%, and 7.6% of the initial contents at the high density (i.e. 0.80 oyster L−1) after 6 h. Barnacles and the combined use of both species, however, showed remarkably lower efficiencies. Our results demonstrated that oysters could potentially be used to improve water quality of shrimp farm effluents especially in the areas where oysters can be easily collected or cultured.

Habibi Motlagh, Saeedeh, Nasrolahi, Ali, Rezaie-Atagholipour, Mohsen (2021): Species assemblage and distribution of turtle barnacles (Cirripedia: Coronuloidea) on foraging green sea turtles (Chelonia mydas) in the Persian Gulf. Journal of Natural History 54 (33-34): 2113-2123, DOI: 10.1080/00222933.2020.1837276, URL: http://dx.doi.org/10.1080/00222933.2020.1837276

The molluscan fauna of the Persian Gulf has recently been relatively well documented, yet there are few records of heterobranch sea slugs (opisthobranchs) from the Arabian parts and no report from the Iranian waters. Here we report for the first time the occurrence of one of these molluscs in the northern Persian Gulf (Bandar Abbas, Iran). Sacoglossan specimens were collected in association with the seaweed, Caulerpa sertularioides. Since morphological attributes were not adequately reliable for species identification, molecular approaches were carried out. Maximum-likelihood and Bayesian Inference analysis of partial DNA sequences of the mitochondrial cytochrome c oxidase subunit I (COI) locus were used for DNA barcoding of large-bodied specimens of Elysia. All Persian Gulf specimens were genetically confirmed as Elysia cf. tomentosa sp. 5, one of at least five morphologically similar but genetically distinct species in the taxonomically challenging and unresolved E. tomentosa complex. This species has previously been recorded only from Australia and Thailand and our finding adds another distant point to the geographic distribution of this species.

This study investigates the performance of artificial intelligence techniques including artificial neural network (ANN), group method of data handling (GMDH) and support vector machine (SVM) for predicting water quality components of Tireh River located in the southwest of Iran. To develop the ANN and SVM, different types of transfer and kernel functions were tested, respectively. Reviewing the results of ANN and SVM indicated that both models have suitable performance for predicting water quality components. During the process of development of ANN and SVM, it was found that tansig and RBF as transfer and kernel functions have the best performance among the tested functions. Comparison of outcomes of GMDH model with other applied models shows that although this model has acceptable performance for predicting the components of water quality, its accuracy is slightly less than ANN and SVM. The evaluation of the accuracy of the applied models according to the error indexes declared that SVM was the most accurate model. Examining the results of the models showed that all of them had some over-estimation properties. By evaluating the results of the models based on the DDR index, it was found that the lowest DDR value was related to the performance of the SVM model.

The current study investigated diatom communities on juvenile green turtles foraging in neritic habitats around five Iranian islands. The primary objectives were to (1) compare species composition, growth form structure, and abundance of diatom communities associated with sea turtles foraging within the restricted boundaries of local feeding pastures, and (2) assess the level of uniqueness of the epizoic diatom flora in comparison with biofilms growing on floating debris. All observations and diatom counts were performed using scanning electron microscopy. The effect of the sampling location was apparent among sea turtle samples and reflected in significantly different cell densities. Diatom abundances were significantly higher on sea turtles (758–1836 cells mm−2 ) than on floating debris samples (9–189 cells mm−2 ). Epizoic diatom communities were composed of 20 diatom taxa and dominated by erect forms belonging to the so-called ‘marine gomphonemoids’, Chelonicola and Poulinea, previously reported on sea turtles from other geographical regions. The diatom flora found on floating debris was composed of 21 taxa. Only four taxa, Amphora cf. bigibba, Cocconeis cf. neothumensis var. marina, Psammodictyon constrictum, and Tabularia affinis, were recorded from both sea turtles and floating debris samples, and none of these exceeded 4% of the average relative abundance on the sea turtle carapaces. The study reveals a clear substratum preference in sea turtle-associated diatoms, with no evidence for species turnover across the investigated region over different sampling seasons, thus confirming previous speculations that sea turtle diatom communities would show a high level of uniqueness and stability.

Biofouling is predicted to increase in the course of global warming, making the study and monitoring of its ecological and economic consequences of great importance. The present study describes, for the first time, recruitment and successional patterns of fouling communities in the Caspian Sea. During one year, short-term panels (STP; replaced every 2 months) and long-term panels (LTP; retrieved after 4, 8 and 12 months) were deployed in the Western Iranian coast of the Caspian Sea. Temporal trends in both sets of panels were evaluated through Generalized Additive Models and discussed in light of the environmental variables registered in each sampling event. Recruitment and successional patterns observed at the community level were mainly driven by barnacles and bryozoans, the dominant taxa over the entire sampling period. Panel coverage, biomass and inorganic to organic matter ratio exhibited clear seasonal patterns in STP, following temperature and chlorophyll a trends. In LTP, coverage and biomass increased over the study period, while the inorganic to organic matter ratio peaked in summer and decreased during autumn and winter months. These results represent a baseline for future studies on biofouling communities in the Caspian Sea, where this topic has been completely neglected.

This paper describes 15 cheilostome bryozoan species obtained from 15 sampling sites along the northern coast of the Persian Gulf in Iran. Two of the cheilostomes are described as new species: Parasmittina cryptoavicularia n. sp. and Trematooecia persica n. sp. The majority of species found in this study (67%) have a tropical to subtropical Indo-Pacific distribution, while the remainder are more widely distributed. Several are fouling species known from warmer seas around the globe. Further sampling efforts are needed to obtain a better estimate of the true bryozoan diversity in the region which is almost certainly much greater than the 15 species described in this study.

While the impact of ocean warming on single species is well described, the impact on marine biofouling communities is not well understood. Effluents of power plants have higher temperatures and can be used as natural large-scale test sites to investigate warming effects on marine ecosystems. In the present study, we evaluated the impact of elevated temperatures in the vicinity of a power plant on macro-biofouling communities in the northern coast of the Persian Gulf. The impact site was on average 2 °C warmer than the control site. Our results demonstrate a significantly different structure and composition of biofouling communities between control and impact sites. Warming led to a 1.5-fold increase in the mean coverage of biofouling communities and slightly decreased functional and species richness. Our results indicated that future warming will likely increase biofouling pressure, while decreasing diversity of communities, particularly in habitats where organisms exist at their upper tolerance limits of temperature.

Anthropogenic changes to the temperature regime of a water body, including but not limited to climate change and thermal pollution, may influence the community structure of species living therein. Among these, benthic communities, due to their limited movement and long life span, are one of the best biological indicators to reflect the impact of environmental stressors. In this regard, the thermal pollution of Pare-Sar power plant in the southern Caspian Sea was used as a natural laboratory to assess the effects of warming on macrobenthic communities’ biomass, abundance, richness, and structure throughout the year. Water temperature near the effluents of the power plant was on average 1.29 °C higher than the control sites. We observed that warming led to an increase in the abundance and species richness of benthic macroinvertebrates. However, benthos biomass was significantly lower in the impact site rather than the control sites, probably due to the increased proportion of small-bodied taxa and decreased growth rate of biomass determinant taxa. Therefore, our findings may be an indication of potential benthic community response to thermal pollution and may provide a baseline for future projections under global climate change scenarios.

The Caspian Sea is the largest land-locked lake in the world that includes numerous endemic species. Because of its enclosed nature, the pollutants entering this water body become entrapped. The present paper examines the influence of human activity and beach morphology on the abundance and distribution of stranded plastic debris along the Caspian Sea coastlines. It would be possible by relating some characteristics of these beaches (population, urbanization, substrate type, and slope of beaches) with the abundance of plastic debris through a PCo analysis. The results showed that in our study area, the most effective factors on plastic debris distribution were urbanization and population followed by the slope and substrate of beaches. Three size classes of plastic debris were defined as “large microplastic” (1 to 25 mm). The density of the large microplastic, mesoplastic, and macroplastic materials on the Caspian Sea coastline was 8.43 ± 0.54, 8.74 ± 0.42, and 7.53 ± 0.30 particles/m2, respectively. Foam was the most abundant microplastic debris along the study area (47.58%), followed by resin pellets (33.93%) and fragments (16.30%), respectively. We also selected the Boujagh National Park with limited accessibility as an appropriate area for the study of marine debris as one sampling station. Cigarette butts and film pieces displayed a different distribution pattern compared to other debris types in the Boujagh National Park station likely due to their distinct buoyancy specification.

Global concern about floating marine debris and its fundamental role in shaping coastal biodiversity is growing, yet there is very little knowledge about debris-associated rafting communities in many areas of the world's oceans. In the present study, we examined the encrusting assemblage on different types of stranded debris (wood, plastic, glass, and metal cans) along the Iranian coast of the Persian Gulf. In total, 21 taxa were identified on 132 items. The average frequency of occurrence (±SE) across all sites and stranded debris showed that the barnacle Amphibalanus amphitrite (68.9 ± 1.1%), the oyster Saccostrea cucullata (40.9 ± 0.7%), the polychaete Spirobranchus kraussii (27.3 ± 0.5%), green algae (22 ± 0.5%) and the coral Paracyathus stokesii (14.4 ± 0.7%) occurred most frequently. Relative substratum coverage was highest for A. amphitrite (44.3 ± 2.7%), followed by green algae (14.4 ± 1.5%), Spirobranchus kraussii (9.3 ± 1.3%), Saccostrea cucullata (7.6 ± 1.3%) and the barnacle Microeuraphia permitini (5.8 ± 0.9%). Despite the significant difference in coverage of rafting species on plastic items among different sites, there was no clear and consistent trend of species richness and coverage from the eastern (Strait of Hormuz) to the western part of the Persian Gulf. Some rafting species (bryozoans and likely barnacles) were found to be non-indigenous species in the area. As floating marine debris can transport non-indigenous species and increase the risk of bio-invasions to this already naturally- and anthropogenically-stressed water body, comprehensive monitoring efforts should be made to elucidate the vectors and arrival of new invasive species to the region.

The first reports of diatoms growing on marine mammals date back to the early 1900s. However, only recently has direct evidence been provided for similar associations between diatoms and sea turtles. We present a comparison of diatom communities inhabiting carapaces of green turtles Chelonia mydas sampled at two remote sites located within the Indian (Iran) and Atlantic (Costa Rica) Ocean basins. Diatom observations and counts were carried out using scanning electron microscopy. Techniques involving critical point drying enabled observations of diatoms and other microepibionts still attached to sea turtle carapace and revealed specific aspects of the epizoic community structure. Species-poor, well-developed diatom communities were found on all examined sea turtles. Significant differences between the two host sea turtle populations were observed in terms of diatom abundance and their community structure (including growth form structure). A total of 12 and 22 diatom taxa were found from sea turtles in Iran and Costa Rica, respectively, and eight of these species belonging to Amphora, Chelonicola, Cocconeis, Navicula, Nitzschia and Poulinea genera were observed in samples from both locations. Potential mechanisms of diatom dispersal and the influence of the external environment, sea turtle behaviour, its life stage, and foraging and breeding habitats, as well as epibiotic bacterial flora on epizoic communities, are discussed.

When juvenile mortality or juvenile growth is impacted by temperature and salinity, these factors have a substantial effect on recruitment success and population dynamics in benthic ecosystems. Using freshly settled cyprids of Amphibalanus improvisus, we investigated the combined effects of temperature (12, 20 and 28 °C) and salinity (5, 15 and 30 psu) on early juvenile stage performance. Mortality as well as size (basal diameter, dry weight, and ash-free dry weight) was monitored for a period of 40 days. Mortality was high (42–63 %) during the first week following attachment, regardless of the temperature and salinity treatments. Subsequently, mortality and size were interactively influenced by temperature and salinity. Highest mortality and lowest size of juveniles occurred at lowest temperature (12 °C) and salinity (5 psu). Apparently, low temperature (12 °C) narrowed the barnacles’ salinity tolerance. Juvenile barnacles constructed more shell material compared to body mass at high temperature and high salinity, while a reverse situation was observed at low temperature and low salinity. Our results demonstrate that environmental changes can directly and/or indirectly alter patterns of survivorship and size. Warming and desalination as predicted for the Baltic Sea in the course of climate change may, however, act antagonistically and compensate each other’s isolated effect on barnacles.

Temperature and salinity shape the distribution and genetic structure of marine communities. Future warming and freshening will exert an additional stress to coastal marine systems. The extent to which organisms respond to these shifts will, however, be mediated by the tolerances of all life-stages and populations of species and their potential to adapt. We investigated nauplius and cypris larvae of the barnacle Balanus (Amphibalanus) improvisus from the Swedish west coast with respect to temperature (12, 20, and 28 °C) and salinity (5, 15, and 30) tolerances. Warming accelerated larval development and increased overall survival and subsequent settlement success. Nauplii developed and metamorphosed best at intermediate salinity. This was also observed in cypris larvae when the preceding nauplii stages had been reared at a salinity of 30. Direct comparisons of the present findings with those on a population from the more brackish Baltic Sea demonstrate contrasting patterns. We conclude that i) B. improvisus larvae within the Baltic region will be favoured by near-future seawater warming and freshening, that ii) salinity tolerances of larvae from the two different populations reflect salinities in their native habitats, but are nonetheless suboptimal and that iii) this species is generally highly plastic with regard to salinity.

We investigated the impacts of warming and elevated pCO2 on newly settled Amphibalanus improvisus from Kiel Fjord, an estuarine ecosystem characterized by significant natural pCO2 variability. In two experiments, juvenile barnacles were maintained at two temperature and three pCO2 levels (20/24 °C, 700–2,140 μatm) for 8 weeks in a batch culture and at four pCO2 levels (20 °C, 620–2,870 μatm) for 12 weeks in a water flow-through system. Warming as well as elevated pCO2 hardly affected growth or the condition index of barnacles, although some factor combinations led to temporal significances in enhanced or reduced growth with an increase in pCO2. While warming increased the shell strength of A. improvisus individuals, elevated pCO2 had only weak effects. We demonstrate a strong tolerance of juvenile A. improvisus to mean acidification levels of about 1,000 μatm pCO2 as is already naturally experienced by the investigated barnacle population.

The world's oceans are warming and becoming more acidic. Both stressors, singly or in combination, impact marine species, and ensuing effects might be particularly serious for early life stages. To date most studies have focused on ocean acidification (OA) effects in fully marine environments, while little attention has been devoted to more variable coastal ecosystems, such as the Western Baltic Sea. Since natural spatial and temporal variability of environmental conditions such as salinity, temperature or pCO(2) impose more complex stresses upon organisms inhabiting these habitats, species can be expected to be more tolerant to OA (or warming) than fully marine taxa. We present data on the variability of salinity, temperature and pH within the Kiel Fjord and on the responses of the barnacle Amphibalanus improvisus from this habitat to simulated warming and OA during its early development. Nauplii and cyprids were exposed to different temperature (12, 20 and 27 degrees C) and pCO(2) (nominally 400, 1250 and 3250 mu atm) treatments for 8 and 4 weeks, respectively. Survival, larval duration and settlement success were monitored. Warming affected larval responses more strongly than OA. Increased temperatures favored survival and development of nauplii but decreased survival of cyprids. OA had no effect upon survival of nauplii but enhanced their development at low (12 degrees C) and high (27 degrees C) temperatures. In contrast, at the intermediate temperature (20 degrees C), nauplii were not affected even by 3250 mu atm pCO(2). None of the treatments significantly affected settlement success of cyprids. These experiments show a remarkable tolerance of A. improvisus larvae to 1250 mu atm pCO(2), the level of OA predicted for the end of the century

The barnacle Amphibalanus eburneus (Gould, 1841), native to the northwest Atlantic Ocean, became nearly cosmopolitan due to extensive shipping activities. In the Caspian Sea, A. eburneus have been reported solely from Azerbaijan and Turkmenistan. The current study provides robust evidence of its occurrence in Iran. We observed that the previously vacant niche on the hard substrates bordering a shrimp farm in Gomishan Wetland, southern Caspian Sea, is now occupied by A. eburneus. The identity of the species was confirmed by both morphological and molecular approaches. Massive development of this (previously thought) brackish species in saline waters (33–57 psu) of the Gomishan Wetland demonstrates the high invasion potential of the species. Although it seems that this introduction has had no impact so far, it can be projected that the entire coastline of the southern Caspian Sea might be colonized by A. eburneus, which may outcompete the native fauna of the area in the future.

The effects of algal diet on larval survival and growth of the barnacle Amphibalanus improvisus was for the first time examined under controlled laboratory conditions. Larvae were obtained by dissecting egg lamellae at later developmental stage out of the adults. Hatched nauplii were reared in 0.6-l glass beakers (200 larvae l-1) on a monoalgal diet of Chaetoceros calcitrans, Chlorella vulgaris and Scenedesmus quadricauda at 1x105 and 2x105 cells ml-1, under continuous light at 25 ±1°C. The rate of development, survival and size (at Stage V) of the larvae were measured for each diet. The majority of nauplius II larvae (~70%) fed with Cha. calcitrans and Chl. vulgaris developed into cyprids within seven days while those fed with S. quadricauda remained at Stage II. A shorter time interval for Stage II to III was observed in larvae fed with a Chl. vulgaris monoalgal diet than Cha. calcitrans. Larvae fed with Cha. calcitrans had shorter developmental intervals for later larval stages (Stages IV–VI). The highest mortality was observed in the treatment with a monoalgal diet of S. quadricauda, while the highest survival was achieved with a diet of Cha. calcitrans. The mixed diet of Cha. calcitrans, Chl. vulgaris and S. quadricauda resulted in a shorter developmental duration of larval cycle (six days). Both food type and food concentration significantly affected the length and width of the nauplius larvae.

In this paper, we record the occurrence for the first time of two sea cucumber species from the Persian Gulf (Hormuz Island). Sea cucumber samples were collected in the sub-tidal zone of the island during low tide. Species identification was accomplished using morphological keys and a review of their ossicles. The collected specimens provide evidence thatHolothuria bacilliandHolothuria insignisare present in the Persian Gulf waters.

The fouling barnacle Amphibalanus amphitrite is a cosmopolitan biomonitor of trace metal bioavailabilities, with an international comparative data set of body metal concentrations. Bioavailabilities of As, Cd, Cr, Cu, Fe, Mn, Pb, V and Zn to A. amphitrite were investigated at 19 sites along the Iranian coast of the understudied Persian Gulf. Commercial and fishing ports showed extremely high Cu bioavailabilities, associated with high Zn bioavailabilities, possibly from antifouling paints and procedures. V availability was raised at one port, perhaps associated with fuel leakage. Cd bioavailabilities were raised at sites near the Strait of Hormuz, perhaps affected by adjacent upwelling off Oman. The As data allow a reinterpretation of the typical range of accumulated As concentrations in A. amphitrite. The Persian Gulf data add a new region to the A. amphitrite database, confirming its importance in assessing the ecotoxicologically significant trace metal contamination of coastal waters across the world.

The fate of key species, such as the barnacle Amphibalanus improvisus, in the course of global change is of particular interest since any change in their abundance and/or performance may entail community-wide effects. In the fluctuating Western Baltic, species typically experience a broad range of environmental conditions, which may preselect them to better cope with climate change. In this study, we examined the sensitivity of two crucial ontogenetic phases (naupliar, cypris) of the barnacle toward a range of temperature (12, 20, and 28°C) and salinity (5, 15, and 30 psu) combinations. Under all salinity treatments, nauplii developed faster at intermediate and high temperatures. Cyprid metamorphosis success, in contrast, was interactively impacted by temperature and salinity. Survival of nauplii decreased with increasing salinity under all temperature treatments. Highest settlement rates occurred at the intermediate temperature and salinity combination, i.e., 20°C and 15 psu. Settlement success of “naive” cyprids, i.e., when nauplii were raised in the absence of stress (20°C/15 psu), was less impacted by stressful temperature/salinity combinations than that of cyprids with a stress history. Here, settlement success was highest at 30 psu particularly at low and high temperatures. Surprisingly, larval survival was not highest under the conditions typical for the Kiel Fjord at the season of peak settlement (20°C/15 psu). The proportion of nauplii that ultimately transformed to attached juveniles was, however, highest under these “home” conditions. Overall, only particularly stressful combinations of temperature and salinity substantially reduced larval performance and development. Given more time for adaptation, the relatively smooth climate shifts predicted will probably not dramatically affect this species.

Effects of epibiotic bacteria associated with macroalgae on barnacle larval attachment were investigated. Eight bacterial isolates obtained from samples of three macroalga species were cultured as monospecies bacterial films and tested for their activity against barnacle (Amphibalanus improvisus) attachment in field experiments (Western Baltic Sea). Furthermore, natural biofilm communities associated with the surface of the local brown alga, Fucus vesiculosus, which were exposed to different temperatures (5, 15 and 20 °C), were harvested and subsequently tested. Generally, monospecies bacterial biofilms, as well as natural microbial assemblages, inhibited barnacle attachment by 20-67%. denaturing gradient gel electrophoresis fingerprints showed that temperature treatment shifted the bacterial community composition and weakened the repellent effects at 20 °C. Repellent effects were absent when settlement pressure of cyprids was high. Nonviable bacteria tended to repel cyprids when compared to the unfilmed surfaces. We conclude that biofilms can have a repellent effect benefiting the host by preventing heavy fouling on its surface. However, severe settlement pressure, as well as stressful temperature, may reduce the protective effects of the alga's biofilm. Our results add to the notion that the performance of F. vesiculosus may be reduced by multiple stressors in the course of global warming.

The effect of different food concentration, substratum, light periodicity, salinity, cyprid density and cyprid age on the settlement of Balanus improvisus were studies. Released larvae were mass reared in 0.6 L glass beakers to the cyprid stage. Then, attachment was monitored once a day. Chaetoceros calcitrans was used as food at three cell concentrations (0.5 x 10(5), 1 x 10(5) and 2 x 10(5) cells mL(-1)). Larval settlement was carried out on two substratum under three light period (12L:12D, 16L:8D and 8L:16D) at seven salinities (7, 12, 15, 18, 25, 28 and 36 ppt). Cyprid density was used from five to 200 larvae per 5 mL of seawater. Cyprids were aged for one to seven days. The maximum and minimum percent settlement was observed at 2 x 10(5) and 0.5 x 10(5) cells mL(-1), respectively. Cyprids settled in higher numbers on polystyrene compared to glass surface. Percent settlement was higher in 8L:16D than another light periods but, no significant difference in percent settlement between 12L:12D and 16L:8D light periods was seen. Differences in settlement at various salinities were not statistically significant except in 10 ppt which percent settlement was significantly higher. Cyprid density did not have any effect on percent settlement but cyprid age had a significant effect on percent settlement.