Species In Coastal Waters Research Articles

Tuft Dynamics and the Reproductive Phenology of Zostera caespitosa on the Southern Coast of Korea

The aim of study is to determine which environmental factors could influence the biological traits of Z. caespitosa, a unique tuft-forming seagrass. This study examined the dynamics of tufts and the growth of Z. caespitosa, along with the environmental factors. The reproductive traits were also examined to estimate the potential importance of sexual reproduction in population persistence. The density of tufts remained constant, and no new tufts produced through seedling recruitment were observed throughout the sampling period. On the other hand, the tuft size and growth exhibited clear seasonal manners and strong correlations with the water temperature, indicating that water temperature regulates the tuft dynamics and growth. The optimal growth temperature for Z. caespitosa at the study site was approximately ~22.5 °C during early summer, with growth severely inhibited during periods of high-water temperatures. Z. caespitosa was characterized by a low flowering percentage and fewer inflorescences, resulting in extremely low potential seed production. Z. caespitosa maintained its populations through clonal tuft growth with low sexual reproduction and restricted growth at high water temperatures. Hence, this seagrass species may be vulnerable to disturbances, exhibiting low resilience and facing a high risk of becoming a threatened species in coastal waters.

Spatial and seasonal distribution of cyanobacteria Moorea species in coastal waters of Tanzania

This study aimed at identifying the presence of harmful cyanobacteria, detecting potential harmful algae toxins and their distribution in three seasons: December to February (hot dry season), March to May (rainy season), and June to November (cool dry season) of 2016. The samples were collected in five study sites in Tanzania: Tumbe, Chwaka, Paje, Bweleo in Zanzibar islands and Songosongo Island, mainland Tanzania, where skin irritation problems were observed in seaweed workers in an earlier study. The cyanobacteria from the Moorea genus were microscopically detected in the seawater, with highest concentrations in the months with the highest seawater temperature or hot dry season, than in the other two seasons. The concentration of Moorea species was significantly higher in Songosongo, Tanzania mainland than in Zanzibar Islands in all three seasons, corresponding to the higher level of nutrients of nutrients (PO43−, NO3− and NH4+) in the prior season. However, the concentrations were considered relatively low and thus not collected during an ongoing algal bloom. This is one of the first studies that detect Moorea sp. in Tanzanian seawater, and complementary studies including genome sequencing to characterize the species are warranted.

The Occurrence of Karenia species in mid-Atlantic coastal waters: Data from the Delmarva Peninsula, USA

A bloom of Karenia papilionacea that occurred along the Delaware coast in late summer of 2007 was the first Karenia bloom reported on the Delmarva Peninsula (Delaware, Maryland, and Virginia, USA). Limited spatial and temporal monitoring conducted by state agencies and citizen science groups since 2007 have documented that several Karenia species are an annual component of the coastal phytoplankton community along the Delmarva Peninsula, often present at background to low concentrations (100 to 10,000 cells L−1). Blooms of Karenia (> 105 cells L−1) occurred in 2010, 2016, 2018, and 2019 in different areas along the Delmarva Peninsula coast. In late summer and early autumn of 2017, the lower Chesapeake Bay experienced a K. papilionacea bloom, the first recorded in Bay waters. Blooms typically occurred summer into autumn but were not monospecific; rather, they were dominated by either K. mikimotoi or K. papilionacea, with K. selliformis, K. brevis-like cells, and an undescribed Karenia species also present. Cell concentrations during these mid-Atlantic Karenia spp. blooms equalled concentrations reported for other Karenia blooms. However, the negative impacts to environmental and human health often associated with Karenia red tides were not observed. The data compiled here report on the presence of multiple Karenia species in coastal waters of the Delmarva Peninsula detected through routine monitoring and opportunistic sampling conducted between 2007 and 2022, as well as findings from research cruises undertaken in 2018 and 2019. These data should be used as a baseline for future phytoplankton community analyses supporting coastal HAB monitoring programs.

Classification of coastal shrimp species using deep learning InceptionResNetV2 with data augmentation

Coastal areas that are rich in shrimp natural resources usually have a strong fishing industry. Shrimp consumption can contribute to the local economy. Several types of shrimp have higher utilization potential in the fishing industry and human consumption. Classification helps sort out shrimp species in coastal waters. Deep learning technology helps identify and separate shrimp species through deep learning with the Convolutional neural network. The seven classes observed were Vaname Shrimp, Tiger Shrimp, Jerbung Shrimp, Giant Prawns, Red Shrimp, Ronggeng Shrimp, and Prawns. The data used is 50 per class, so 350 images are used. Due to dataset limitations, the proposed contribution is an initial Resnet architecture with augmentation. Resnet helps perform in-depth training to save training computation time, and improvements add variety to limited amounts of data. The result is that the average accuracy of the model is 99.4%, with an average training computation time of 7 and a half minutes. The MSE misclassification value was 0.0143, RMSE was 0.1195, and MAE was 0.0086. Testing tests and testing data on the model only takes 1-2 seconds. Prediction accuracy ranges from 90.01%-99.8%.

Physiological basis and differentially expressed genes in the salt tolerance mechanism of Thalassia hemprichii.

Seagrass plays a vital role in the stability of marine ecology. The human development of marine resources has greatly affected the survival of seagrass. Seawater salinity is one of the important factors affecting its survival. Seagrass can survive in high saline environments for a long time and has evolved a variety of effective tolerance mechanisms. However, little is known about the molecular mechanisms underlying salinity tolerance by seagrass. Thalassia hemprichii is a seagrass species with a global distribution. It is also an ecologically important plant species in coastal waters. Nevertheless, the continuous environmental deterioration has gradually reduced the ecological niche of seagrasses. In this study, experiments were conducted to examine the effects of salinity changes on T. hemprichii. The result showed that the optimal salinity for T. hemprichii is 25 to 35 PSU. Although it can survive under high and low salinity, high mortality rates are common in such environments. Further analyses revealed that high salinity induces growth and developmental retardation in T. hemprichii and further causes yellowing. The parenchyma cells in T. hemprichii also collapse, the structure changes, soluble sugar accumulates rapidly, soluble proteins accumulate rapidly, the malondialdehyde (MDA) content reduces, and lipid peroxidation reduces in plant membranes. The molecular mechanisms of salt tolerance differ significantly between marine and terrestrial plants. We found 319 differentially expressed genes (DEGs). These genes regulate transport and metabolism, promoting environmental adaptation. The expression of these genes changed rapidly upon exposure of T. hemprichii to salinity stress for three hours. This is the first report on the physiological and biochemical changes and gene expression regulation of T. hemprichii under different salinity conditions. The findings of this study well deepen our understanding of T. hemprichii adaptations to changes in the shoal living environment.

Evaluation of seagrass beds as a foraging and nursery habitat based on the structure of the fish community in Nusmapi Island, West Papua, Indonesia

Abstract. Manangkalangi E, Sembel L, Tebaiy S, Manuputty A, Rumayomi MR, Musyeri P, Sawaki D, Orissu D, Manumpil AW, Kaber Y. 2022. Evaluation of seagrass beds as a foraging and nursery habitat based on the structure of the fish community in Nusmapi Island, West Papua, Indonesia. Biodiversitas 23: 5539-5550. Seagrass beds are one of the ecosystems inhabited by various coastal aquatic fauna, including fish. However, information on the temporal role of this ecosystem for fish fauna, particularly diurnal and nocturnal, is still limited. Therefore, this study was conducted to describe daily variations in the fish species composition, their ecological index, developmental stages, and trophic groups in a seagrass bed on Nusmapi Isl., Manokwari. The species composition differed between day and night sampling periods based on the results obtained from 40 species of fish belonging to 21 families and 7 orders. Furthermore, fish species consisted of three trophic groups (omnivores, carnivores, and herbivores), with omnivores and carnivores dominating during the day and at night by 48.6% and 87.5%, respectively. Species found in seagrass beds majorly consisted of juvenile stage individuals (65.9%). Individual abundance varied from day to night and was mainly found among group-forming species, such as S. spinus, S. trilineata, S. punctatissimum, and M. pralinia. The index of diversity, evenness, and dominance at the two relatively similar sampling times described the overall stability of fish communities in seagrass beds. The results indicate that seagrass beds serve as foraging and nursery grounds for many fish species in coastal waters. In addition, the management and protection of fish biodiversity and coastal fishery resources are affected by the ecosystem function.

Unoccupied aerial video (UAV) surveys as alternatives to BRUV surveys for monitoring elasmobranch species in coastal waters

Abstract Effective conservation strategies are founded by baseline information on abundance and diversity estimates. Method choice can influence the success of baseline surveys as method performance is variable and needs to be selected based on habitat and taxa. Here, we assess the suitability of unoccupied aerial vehicle (UAV) surveys, specifically multi-rotor “drones”, and baited remote underwater video (BRUV) surveys in shallow-water habitats to quantify elasmobranch abundance and diversity in the Saudi Arabian central Red Sea. Our results show that the number of elasmobranchs h−1 observed using UAV surveys exceeded that of BRUV surveys by two orders of magnitude, indicating that the increased spatial coverage of UAV surveys is beneficial for long-term monitoring projects. BRUV surveys detected a greater number of species within reef habitats, whereas UAV surveys detected a greater number of species within sandflat habitats, indicating the value of multi-method approaches for regional biodiversity studies. Here, we provide the first insight into elasmobranchs associated with sandflat habitats in Saudi Arabia, emphasising the importance of these habitats to stingrays and the need for further information on elasmobranch habitat use to better inform management and conservation efforts in the face of rapid coastal developments across the Red Sea.

Identifying key processes and drivers affecting the presence of non-indigenous marine species in coastal waters

Identifying key processes and drivers affecting the presence of non-indigenous marine species in coastal waters

Aspects of the biology of two Nemipterus species in coastal waters around Okinawa Island, Ryukyu Archipelago

Aspects of the biology of two <i>Nemipterus</i> species in coastal waters around Okinawa Island, Ryukyu Archipelago

Variations in female swordtip squid Uroteuthis edulis life history traits between southern Japan and northern Taiwan (Northwestern Pacific)

Swordtip squid Uroteuthis edulis is a commercially important species in coastal waters throughout the Northwestern Pacific, including those of Japan and Taiwan. Despite the importance of U. edulis to fisheries, previous studies on the life history traits (growth rate, size at maturity, and fecundity) of its populations in the Northwestern Pacific have been localized and region specific. Thus, we report life history traits of female swordtip squid from the waters off southern Japan and northern Taiwan, to identify seasonal variations within each population, as well as geographical variations between them. Variations in life history traits, including growth rate, mantle length (ML) at maturity, and female reproductive traits (gonadosomatic index, fecundity and egg size), are described and recognized to vary seasonally in both populations. Winter spawners in Japan have the highest growth rate, followed by spring spawners and summer spawners. Spring spawners in Taiwan mature at a younger age than autumn spawners. Geographical variations between populations are reported: fecundity level and egg size of spring spawners in Japan differ from those of spring and autumn spawners in Taiwan, but those of summer spawners in Japan are similar to those of spring and autumn spawners in Taiwan. Data on seasonal and geographical variations in life history traits of U. edulis are useful for effective squid fisheries management.

Variation of Amoebophrya community during bloom of Prorocentrum donghaiense Lu in coastal waters of the East China Sea

The parasitic dinoflagellates in the genus Amoebophrya infect and kill a number of free-living dinoflagellates. The parasitoid has the potential to regulate harmful dinoflagellate blooms due to its high offspring production rates and a certain degree of host specificity. The planktonic dinoflagellate Prorocentrum donghaiense Lu is a commonly observed harmful algal species in coastal waters of China, and limited studies have been conducted to explore the ecological roles of parasitism in association with bloom dynamics. Thus, the in situ occurrence, prevalence, and dynamics of Amoebophrya during the recurrent blooms of P. donghaiense were systemically studied via morphological observations and high-throughput sequencing. The parasitic infections were identified microscopically in six dinoflagellate taxa with prevalence up to 5.13%, while Amoebophrya infection in the bloom-forming species P. donghaiense was rare (<0.01%), suggesting that P. donghaiense was free of the top-down control of Amoebophrya in the area. In addition, high-throughput sequencing of environmental DNA revealed that Amoebophrya co-dominated both the initiation and termination stages of the P. donghaiense bloom (up to 21.20% of OTU), but was less abundant during persistence of the bloom (3.70% of OTU). Further, the dynamics of Amoebophrya in the water column possessed similar patterns as revealed by qRT-PCR, in which high copy numbers of Amoebophrya (up to 3.60 × 109 copies L−1) were detected in the initiation and termination stages of the P. donghaiense bloom and low copy numbers (1.16 × 109 copies L−1) during persistence of the bloom. These findings manifested the paradoxical dynamics and complicated ecological strategies of Amoebophrya organisms during dinoflagellate blooms that need further study.

Rough-toothed dolphins (Cetartiodactyla: Delphinidae) habitat use in coastal urban waters of the South-western Atlantic

AbstractRough-toothed dolphins (Steno bredanensis) are regularly present in continental shelf areas of the South-western Atlantic. However, there is little information on the natural history and ecology of these delphinids. This study evaluated the occurrence, habitat use and individual movements of the species in coastal waters off Rio de Janeiro, south-eastern Brazil. Data were obtained from boat surveys between August 2011 and May 2018, during which rough-toothed dolphins were sighted in 21 distinct events, predominantly in autumn and winter. The mean group size was 29 individuals. Rough-toothed dolphins were usually recorded 130 to 2300 m from the coast, between 7.6 and 28 m depths. In total, 115 individuals were catalogued through dorsal fin marks and 61 (53%) were resighted between one (47.5%) and four (9.8%) occasions. The interval between resightings ranged from seven to 2087 days (mean = 268). Agglomerative hierarchical clustering indicated 30 individuals (49.2%) in low degree, 12 (19.7%) in medium degree and 19 (31.1%) in high degree of site fidelity. Dolphins showed a higher frequency of low degree of habitat use, despite the presence of multiyear recaptures, which may be related to the prevalence of dolphin occurrence in autumn and winter, a large home range and/or the abundance and distribution of food resources. Dedicated surveys and regional collaboration are needed to evaluate the home range and population status of this species for their effective conservation. Our findings enhanced knowledge of this little studied species facing increasing anthropogenic threats in coastal waters off Rio de Janeiro.

Age and Growth of Hardhead Catfish and Gafftopsail Catfish in Coastal Louisiana, USA

AbstractThe Hardhead Catfish Ariopsis felis and Gafftopsail Catfish Bagre marinus are marine catfishes that have low recreational and commercial landings in U.S. waters, although they are among the most abundant species in coastal waters of the Gulf of Mexico. Few biological studies exist on marine catfishes, with most studies focusing on their unique reproductive biology. This study evaluated weight–length relationships for Gafftopsail Catfish (n = 264) and Hardhead Catfish (n = 823) sampled from across coastal Louisiana, USA, during 2016–2018; subsamples (93 and 266, respectively) were aged using lapilli for age and growth analyses. Hardhead Catfish showed a small but significant difference in weight as a function of length between males and females, with females being slightly heavier than males at any given length. No sexual dimorphism in weight and length was observed in Gafftopsail Catfish. Ages ranged from 0 to 10 years for Gafftopsail Catfish and from 0 to 24 years for Hardhead Catfish. Both sexes of Gafftopsail Catfish attained larger maximum average sizes (asymptotic length L∞) and exhibited larger growth coefficients (k) than both sexes of Hardhead Catfish. Length at age of Hardhead Catfish in Louisiana was greater than that of Florida fish. The estimated k for Gafftopsail Catfish in Louisiana was almost three times greater than that observed in Florida, with fish reaching their L∞ rapidly compared to those in Florida. Given the increasing evidence for an equilibrium life history strategy (i.e., K strategy), the spatial differences in size at age, and the potential for increased exploitation, continued investigations into both species’ biology and life history should be undertaken.

Species Diversity of Planktonic Copepods and Distribution Characteristics of Its Major Species in Coastal Waters of Korea

Species Diversity of Planktonic Copepods and Distribution Characteristics of Its Major Species in Coastal Waters of Korea

The environmental implication of diatom fossils in the surface sediment of the Changjiang River estuary (CRE) and its adjacent area

In order to depict the distribution of diatom fossils in surface sediments and to establish a reliable reference data for further paleoenvironmental study in the Changjiang (Yangtze) River estuary and its adjacent waters, the diatom fossils from 34 surface sediment samples and their relationship with environmental variables were analyzed by principal component analysis and redundancy correspondence analysis. The diversity and abundance of diatom fossils were analyzed. Some annual average parameters of the overlying water (salinity, temperature, turbidity, dissolved oxygen, depth, dissolved inorganic nitrogen, dissolved inorganic phosphate and dissolved inorganic silicate) were measured at each sampling site. A total of 113 diatom taxa and one silicoflagellate species were identified in the investigation area. Diatom fossils were better preserved in fine sediments. The absolute abundance of diatom fossils did not significantly differ between inshore and offshore areas, the species diversity decreased from inshore to offshore. This may be because high nutrients and low salinity promoted the growth of more brackish species in coastal waters. The diatom taxa were divided into three groups, on the basis of their response and indication to environmental changes. For example, Actinocyclus ehrenbergii and Cyclotella stylorum were dominant in coastal waters (Group 1 and Group 3) with high nutrients and low salinity; the relative abundances of Paralia sulcata and Podosira stelliger were significantly higher in offshore sites (Group 2, average 39.5%), which were characterized by high salinity and deep water. Four environmental variables (salinity, dissolved inorganic nitrogen, temperature and water depth) explained the composition and distribution of diatom taxa independently ( P< 0.05), this finding can be applied in further paleoenvironmental reconstruction research in this area.

Fungal assemblages associated with commercial bivalve species in coastal waters of the Sea of Japan, Russia

Abstract A mycological study of three major commercial bivalve species, Yesso scallop Mizuhopecten yessoensis, Pacific oyster Crassostrea gigas, and bay mussel Mytilus trossulus, from the coastal waters off Rikord Island (Peter the Great Bay, Sea of Japan) has been conducted. A total of 52 species of filamentous fungi from 19 genera of ascomycetes (and their anamorphic stages) and zygomycetes were isolated from shells and internal organs of the examined bivalves. Thirty-eight species (18 genera) of filamentous fungi were isolated from Yesso scallop, 21 species (eight genera) from Pacific oyster and 10 species (seven genera) from bay mussel. The studied bivalves showed a low degree of similarity in the diversity of the filamentous fungi. The identified filamentous fungi of the genera Aspergillus, Penicillium, Cladosporium, Chaetomium, etc. belong to a group of opportunistically pathogenic and toxigenic microorganisms that can cause mycoses and mycotoxicoses in aquatic animals.

Radiocesium in seawater, sediments, and marine megabenthic species in coastal waters off Fukushima in 2012–2016, after the 2011 nuclear disaster

In bottom-sediment samples collected in 2012 from a coastal strip (∼30 km × 120 km) off the Fukushima Daiichi Nuclear Power Plant (FDNPP), radiocesium activity concentrations were generally higher south of the FDNPP, with high activity concentration patches in the north. In periodic surveys conducted at nearshore sites during 2012–2016, no clear temporal trends were observed in radiocesium activity concentrations in seawater or bottom sediment, and activity concentrations were higher in fish than in invertebrates. During 2012–2014, radiocesium activity concentrations tended to decrease in fish, but during 2012–2013 in the south, some increases were observed. Radiocesium activity concentrations were significantly higher in some fish (e.g., Okamejei kenojei) directly offshore and south of the FDNPP than in the north. Activity concentrations in fish stomach contents were significantly correlated with those in muscle tissue, suggesting that the consumption of contaminated prey contributed greatly to radiocesium contamination in demersal fish.

Eco-Evolutionary Processes Generating Diversity Among Bottlenose Dolphin, Tursiops truncatus, Populations off Baja California, Mexico

For highly mobile species that nevertheless show fine-scale patterns of population genetic structure, the relevant evolutionary mechanisms determining structure remain poorly understood. The bottlenose dolphin (Tursiops truncatus) is one such species, exhibiting complex patterns of genetic structure associated with local habitat dependence in various geographic regions. Here we studied bottlenose dolphin populations in the Gulf of California and Pacific Ocean off Baja California where habitat is highly structured to test associations between ecology, habitat dependence and genetic differentiation. We investigated population structure at a fine geographic scale using both stable isotope analysis (to assess feeding ecology) and molecular genetic markers (to assess population structure). Our results show that there are at least two factors affecting population structure for both genetics and feeding ecology (as indicated by stable isotope profiles). On the one hand there is a signal for the differentiation of individuals by ecotype, one foraging more offshore than the other. At the same time, there is differentiation between the Gulf of California and the west coast of Baja California, meaning that for example, nearshore ecotypes were both genetically and isotopically differentiated either side of the peninsula. We discuss these data in the context of similar studies showing fine-scale population structure for delphinid species in coastal waters, and consider possible evolutionary mechanisms.

Sedimentary evolution of the Yangtze River mouth (East China Sea) over the past 19,000 years, with emphasis on the Holocene variations in coastal currents

Water mass variations in the early Yangtze estuary during the postglacial transgression have not been thoroughly studied. This research gap has hampered the understanding of riverine sediment ‘source to sink’ processes in this region. This study presents the results of integrated analyses of grain size, pollen-spore-dinocyst assemblages, benthic foraminifera and ostracods from a borehole, H5, located at the northern Yangtze mouth, to investigate the complete sedimentary history and associated variations in coastal currents since 19ka. At the core site, a fluvial floodplain developed from ca. 19–11.3ka, whereas an estuary to shelf to subaqueous delta prevailed during most of the Holocene. Based on changes in the dominant microfauna species, which mainly consist of Chinese coastal water species, two main current patterns were distinguished: one dominated by the Yellow Sea coastal current (YSCC) before ca. 7.9ka and one dominated by the Yangtze dilute water (YDW). Marked increases in open-sea saline species, including Bolivina robusta, and stratified water dinocyst species Spiniferites ramous and Spiniferites spp. were interpreted as the encroachment of the Taiwan warm current (TWWC) and the intensification of the YDW, respectively. The YDW and TWWC penetrated the area dominated by the YSCC before 7.9ka, which was likely related to intensity variations in the Kuroshio Current (KC) and Asian summer monsoon (ASM). Under maximal ASM and KC conditions, upwelling resulted from the intensified intrusion of the TWWC, as indicated by the blooming of Bolivina robusta from 7.9–6.3ka. After ca. 6ka, the YDW clearly weakened due to the decline of the ASM, yet the Yangtze plume prevailed due to the rapid seaward migration of the Yangtze mouth. Considering the dominance of the YSCC in the early Holocene, Yellow River-derived sediment likely represented a large proportion of the material delivered to the early Yangtze estuary.

Evaluation of a Ferrozine Based Autonomous in Situ Lab-on-Chip Analyzer for Dissolved Iron Species in Coastal Waters

The trace metal iron (Fe) is an essential micronutrient for phytoplankton growth and limits, or co-limits primary production across much of the world's surface ocean. Iron is a redox sensitive element, with Fe(II) and Fe(III) co-existing in natural waters. Whilst Fe(II) is the most soluble form, it is also transient with rapid oxidation rates in oxic seawater. Measurements of Fe(II) are therefore preferably undertaken in situ. For this purpose an autonomous wet chemical analyzer based on lab-on-chip technology was developed for the in situ determination of the concentration of dissolved (<0.45 μm) Fe species (Fe(II) and labile Fe) suitable for deployments in a wide range of aquatic environments. The spectrophotometric approach utilizes a buffered ferrozine solution and a ferrozine/ascorbic acid mixture for Fe(II) and labile Fe(III) analyses, respectively. Diffusive mixing, color development and spectrophotometric detection take place in three separate flow cells with different lengths such that the analyzer can measure a broad concentration range from low nM to several μM of Fe, depending on the desired application. A detection limit of 1.9 nM Fe was found. The microfluidic analyzer was tested in situ for nine days in shallow waters in the Kiel Fjord (Germany) along with other sensors as a part of the SenseOCEAN EU-project. The analyzer's performance under natural conditions was assessed with discrete samples collected and processed according to GEOTRACES protocol [acidified to pH < 2 and analyzed via inductively coupled plasma mass spectrometry (ICP-MS)]. The mechanical performance of the analyzer over the nine day period was good (consistent high precision of Fe(II) and Fe(III) standards with a standard deviation of 2.7% (n = 214) and 1.9% (n = 217), respectively, and successful completion of every programmed data point). However, total dissolved Fe was consistently low compared to ICP-MS data. Recoveries between 16 and 75% were observed, indicating that the analyzer does not measure a significant fraction of natural dissolved Fe species in coastal seawater. It is suggested that an acidification step would be necessary in order to ensure that the analyzer derived total dissolved Fe concentration is reproducible and consistent with discrete values.