Nursery Origin Research Articles

Otolith microchemistry identifies shallow, intertidal-dominated estuaries as important nurseries for sand flounder in New Zealand

Estuaries provide critical habitat, food, and refuge for juvenile fish. Elemental concentrations in otoliths can retrospectively identify estuarine nursery habitats that contribute disproportionately to adult populations, providing valuable information for fisheries and coastal ecosystems. The present study aimed to (1) compare elemental signatures of juvenile (age 0+) sand flounder Rhombosolea plebeia otoliths collected from 9 estuaries in east Otago, New Zealand, and (2) assess the application of otolith microchemistry for identifying the nursery habitats contributing to adult (age 1+) sand flounder from the coastal shelf population. Otoliths from juvenile flounder were collected in November 2020, and adults of the same cohort were collected in the winter/spring of 2022. Laser ablation inductively coupled plasma mass spectrometry quantified 12 element concentrations within the post-settlement region of juvenile and adult otoliths using depth-profiling and ablation transects, respectively. Significant differences in post-settlement elemental concentrations were detected among estuaries. Juvenile and adult sand flounder were classified to their nursery origin using canonical analysis of principal coordinates. Grouping estuaries by the New Zealand Estuary Trophic Index classification scheme improved the overall juvenile classification accuracy from 56.7% (51/90) to 82.2% (74/90). Adult sand flounder (n = 78) were classified to have originated from shallow intertidal dominated estuaries (62%), followed by Otago Harbour (32%) and shallow, short residence time river and tidal river with adjoining lagoon estuaries (6%). The results highlight how otolith microchemistry can provide information on the use of critical estuarine nursery habitats for a commercially important species.

New Insights in Lifetime Migrations of Albacore Tuna (Thunnus alalunga, Bonnaterre, 1788) between the Southwest Indian and the Southeast Atlantic Oceans Using Otolith Microchemistry

To clarify potential trans-oceanic connectivity and variation in the natal origin of albacore tuna (Thunnus alalunga) from the southwest Indian Ocean (SWI) and the southeast Atlantic (SA), lifetime otolith elemental signatures were assessed from 46 adults sampled from Reunion Island, and 26 juveniles(group 2+) sampled from two locations along the Atlantic coast of South Africa. LA-ICP-MS analysis was used to assess the multi-elemental composition in B, Ba, Mg, P, Sr, and Zn along the otolith edge (chemical signatures of the capture area), but also near the otolith primordium (spawning origin) and in an area located at 1400–1600 µm from it (nursery origin). Two groups of distinct near-primordium multi-elemental signatures, denoting potentially discrete spawning origins (SpO), were identified using hierarchical clustering. Each of the two SpO was found to contribute to the albacore stocks from all the areas sampled, suggesting a common spawning origin in some fish from the SWI and from the SA, and complex migrations between the two oceans. Three potentially discrete primary nursery sites were identified, each contributing to SA juvenile and SWI adult capture sites differently. The timing for the trans-oceanic movements observed for each albacore capture zone and its implications for local stock management are discussed.

Nursery origin of yellowfin tuna in the western Atlantic Ocean: significance of Caribbean Sea and trans-Atlantic migrants

Natural geochemical markers in the otolith of yellowfin tuna (Thunnus albacares) were used to establish nursery-specific signatures for investigating the origin of fish captured in the western Atlantic Ocean (WAO). Two classes of chemical markers (trace elements, stable isotopes) were used to first establish nursery-specific signatures of age-0 yellowfin tuna from four primary production zones in the Atlantic Ocean: Gulf of Mexico, Caribbean Sea, Cape Verde, and Gulf of Guinea. Next, mixture and individual assignment methods were applied to predict the origin of sub-adult and adult yellowfin tuna from two regions in the WAO (Gulf of Mexico, Mid Atlantic Bight) by relating otolith core signatures (corresponding to age-0 period) to baseline signatures of age-0 fish from each nursery. Significant numbers of migrants from Caribbean Sea and eastern Atlantic Ocean (EAO) production zones (Gulf of Guinea, Cape Verde) were detected in the WAO, suggesting that fisheries in this region were subsidized by outside spawning/nursery areas. Contributions from local production (Gulf of Mexico) were also evident in samples from both WAO fisheries, but highly variable from year to year. High levels of mixing by yellowfin tuna from the different production zones and pronounced interannual trends in nursery-specific contribution rates in the WAO emphasize the complex and dynamic nature of this species’ stock structure and population connectivity. Given that geographic shifts in distribution across national or political boundaries leads to governance and management challenges, this study highlights the need for temporally resolved estimates of nursery origin to refine assessment models and promote the sustainable harvest of this species.

Otolith microchemistry to investigate nursery site fidelity and connectivity of juvenile European sea bass in Ireland

Knowledge of the role that nurseries play in the growth and survival of juvenile European sea bass Dicentrarchus labrax is essential to provide information for sustainable stock management. To examine D. labrax nursery fidelity, multi-annual geochemical tags from the otoliths of 385 juveniles (0-group, 1-group and 2-group) were collected in 4 estuaries along the south coast of Ireland, close to the northern limit of its range. This study identified high between-estuary discrimination of 0-group otolith geochemical tags over multiple years. It also confirmed that over 91% of captured 1-group D. labrax remain close to their original settlement sites irrespective of sampling year. Although the capture in individual estuaries of 2-group D. labrax was less common, otolith geochemical tags indicated >95% fidelity to their original settlement sites. Where migration between estuaries was inferred, it was restricted to an adjacent estuary (<50 km coastal distance). The consistency of the multi-annual geochemical tag signatures observed will enable assignment of nursery origin to adult D. labrax which disperse around the coast of Ireland and ultimately allow the identification of estuary nursery sites that contribute most to the adult stock.

Powdery mildew epidemics in the nursery: role of chasmothecia in epidemic initiation and fungicide regimes to limit chasmothecia formation

Powdery mildew caused by Podosphaera cerasi is a detrimental fungal disease for the sweet cherry industry. Epidemics in orchards are initialized by ascospores that are released from chasmothecia generated in the fall of the previous year, however, the initiation of epidemics in nurseries has not been explored. The current study aimed to evaluate the origin of disease epidemics in Washington State cherry tree nurseries and to evaluate the efficacy of different fungicide regimes to suppress chasmothecia numbers and ascospore viability. Greenhouse and lab assays in the present study showed that chasmothecia from the nursery are not contributing to powdery mildew epidemics and the disease is originating from an external source such as wind-blown conidia from neighboring orchards. Additionally, intensive synthetic fungicide regimes and late-season JMS Stylet-Oil applications were found to be viable options to inhibit chasmothecia formation. As chasmothecia with a nursery origin are not the initial inoculum, late season fungicide applications to limit chasmothcia formation should only be applied in an orchard setting. Orchard managers can limit epidemics by implementing late-season fungicide applications into their IPM plan that target chasmothecia. Future research should evaluate the dispersal of conidia throughout the cherry tree growing industry of Washington and their role in powdery mildew epidemics in nurseries. Moreover, the physiological and genetic differences between chasmothecia in the nursery and the orchard should be evaluated.

Nursery origin and population connectivity of swordfish Xiphias gladius in the North Pacific Ocean.

Element:Ca ratios in the otolith cores of young‐of‐the‐year (YOY) swordfish, Xiphias gladius, were used as natural tracers to predict the nursery origin of subadult and adult swordfish from three foraging grounds in the North Pacific Ocean (NPO). First, the chemistry of otolith cores (proxy for nursery origin) was used to develop nursery‐specific elemental signatures in YOY swordfish. Sagittal otoliths of YOY swordfish were collected from four regional nurseries in the NPO between 2000 and 2005: (1) Central Equatorial North Pacific Ocean (CENPO), (2) Central North Pacific Ocean (CNPO), (3) Eastern Equatorial North Pacific Ocean (EENPO) and (4) Western North Pacific Ocean (WNPO). Calcium (43Ca), magnesium (24Mg), strontium (88Sr) and barium (138Ba) were quantified in the otolith cores of YOY swordfish using laser ablation inductively coupled plasma mass spectrometry. Univariate tests indicated that three element:Ca ratios (Mg:Ca, Sr:Ca and Ba:Ca) were significantly different among nurseries. Overall classification success of YOY swordfish to their nursery of collection was 72% based on quadratic discriminant analysis. Next, element:Ca ratios in the otolith cores of subadults and adults collected from three foraging grounds where targeted fisheries exist (Hawaii, California and Mexico) were examined to calculate nursery‐specific contribution estimates. Mixed‐stock analysis indicated that the CENPO nursery contributed the majority of individuals to all three foraging grounds (Hawaii 45.6 ± 13.2%, California 84.6 ± 10.8% and Mexico 64.5 ± 15.9%). The results from this study highlight the importance of the CENPO nursery and provide researchers and fisheries managers with new information on the connectivity of the swordfish population in the NPO.

Discrimination of yellowfin tuna Thunnus albacares between nursery areas in the Indian Ocean using otolith chemistry

Yellowfin tuna Thunnus albacares is a highly exploited species in the Indian Ocean. Yet, its stock structure is still not well understood, hindering assessment of the stock at a suitable spatial scale for management. Here, young-of-the-year (<4 mo) yellowfin tuna otoliths were collected in 2018 and 2019, from 4 major nursery areas in the Indian Ocean: Madagascar, Seychelles-Somalia, Maldives and Sumatra. First, direct age estimates were made in a subset of otoliths by visually counting microincrements to identify the portion of the otolith corresponding to the larval stage. We then developed 2-dimensional maps of trace element concentrations to examine spatial distribution of elements across otolith transverse sections. Different distribution patterns were observed among the elements analysed; Li, Sr and Ba were enriched in the portion of the otolith representing early life, whereas Mn and Mg concentrations were heterogeneous across growth bands. Last, we analysed inter-annual and regional variation in otolith chemical composition using both trace elements (Li, Mg, Sr, Ba and Mn) and stable isotopes (δ13C and δ18O). Significant regional variation in otolith chemical signatures was detected among nurseries, except between Madagascar and Seychelles-Somalia. Otolith δ13C and δ18O were important drivers of differentiation between western (Madagascar and Seychelles-Somalia), Maldives and Sumatra nurseries, whereas the elemental signatures were cohort specific. Overall nursery assignment accuracies were 69-71%. The present study demonstrates that baseline chemical signatures in the otoliths of yellowfin tuna are regionally distinct and can be used as a natural tag to investigate the nursery origin of older individuals in the Indian Ocean.

Natural tags identify nursery origin of a coastal elasmobranch Carcharhinus leucas

Abstract Traditional methods for evaluating the importance of elasmobranch nursery habitats have focused on estimating densities or abundances of juveniles within individual nurseries; however, rates of juvenile mortality may vary among nurseries. Thus, abundance may not reflect contribution to adult populations, and contribution estimates require methods to identify the nursery origin of adults. We evaluated the use of natural tags, vertebral chemistry (stable isotope analysis, elemental analysis) and genetic markers, to identify bull shark Carcharhinus leucas nursery origin along the Texas coast (northwestern Gulf of Mexico) at multiple spatial scales. Sharks were most accurately assigned (89% accuracy) to their regional origin (Northern vs. Southern Texas) using a combination of vertebral chemistry and genetic markers. Accuracy decreased when incorporating only one type of natural tag (vertebral chemistry: 58%–84%; genetics: 30%–58%), or when assigning sharks among nurseries grouped into three or four regions (30%–71%; ~100 km spatial scale). Synthesis and applications. We describe a novel method integrating multiple natural tags to identify the nursery origin of a highly migratory coastal elasmobranch, over smaller spatial scales than previously investigated. This framework provides a powerful tool to estimate the relative source (nursery) contributions to adult populations of highly mobile species, which represent production estimates sought in the designation of essential fish habitat and ultimately incorporated into marine spatial planning practices.

Wide-Ranging Temporal Variation in Transoceanic Movement and Population Mixing of Bluefin Tuna in the North Atlantic Ocean

Uncertainty regarding the movement and population exchange of Atlantic bluefin tuna (Thunnus thynnus) from the two primary spawning areas (Gulf of Mexico, Mediterranean Sea) is increasingly implicated as a major impediment for the conservation of this species. Here, two mixture methods were applied to natural chemical markers (18O and 13C) in otoliths (ear stones) to comprehensively investigate the nature and degree of transoceanic movement and mixing of eastern and western populations in several areas of the North Atlantic Ocean that potentially represent mixing hotspots. Areas investigated occurred on both sides of the 45W management boundary as well as waters off the coast of Africa (Morocco, Canary Islands) where both populations are known to occur. Projections of population composition (i.e., natal or nursery origin) from a multinomial logistic regression (MLR) classification method with different probability thresholds were generally in agreement with maximum likelihood estimates from the commonly used mixed-population program HISEA; however, predicted contributions for the less abundant population were occasionally higher for MLR estimates. Both MLR and HISEA clearly showed that mixing of Atlantic bluefin tuna in the Central North Atlantic Ocean was highly variable from year to year with expatriates of eastern or western origin commonly crossing into the other management area. Pronounced transoceanic movement and mixing of western migrants was also present off the coast of Africa, with the occurrence of western migrants in the Canary Islands and Morocco ranging from zero to the majority of the individuals assayed for the years examined. Results indicate highly variable rates of movement and population exchange for Atlantic bluefin tuna, highlighting the need for temporally resolved estimates of natal origin in mixing hotspots to improve population models used to evaluate the status of this threatened species.

Genetic and phenotypic variation of Phytophthora crassamura isolates from California nurseries and restoration sites

Phenotypic and sequence data were used to characterize 28 isolates resembling Phytophthora megasperma from 14 host species in 2 plant production facilities and 10 restoration sites across the San Francisco Bay Area (California; USA). Size of the oogonia and DNA sequences (nuclear internal transcribed spacer (ITS) and mitochondrial cytochrome c oxidase subunit 1 (COX 1)) were compared, and sensitivity to mefenoxam and pathogenicity were measured. Based on ITS 61 % of isolates matched ex-type sequences of Phytophthora crassamura from Italy, and the remainder matched or were close to the P. megasperma ex-type. However, all California P. crassamura genotypes belonged to four unique COX 1 haplotype lineages isolated from both nurseries and restoration sites. Although lineages were sensitive to mefenoxam, a significant difference in sensitivity was identified, and all continued growth in-vitro. These results suggested previous mefenoxam exposure in plant production facilities resulting in tolerance. In conclusion, all evidence pointed to a nursery origin of novel P. crassamura lineages found in California restoration sites. In this study, COX 1 sequences and oogonia size provided information relevant to identify geographic and evolutionary intraspecific variation within P. crassamura, and was additionally used to track the spread of this species from nurseries into wildlands.

Establishing nursery estuary otolith geochemical tags for Sea Bass (Dicentrarchus labrax): Is temporal stability estuary dependent?

The ability to determine connectivity between juveniles in nursery estuaries and adult populations is an important tool for fisheries management. Otoliths of juvenile fish contain geochemical tags, which reflect the variation in estuarine elemental chemistry, and allow discrimination of their natal and/or nursery estuaries. These tags can be used to investigate connectivity patterns between juveniles and adults. However, inter-annual variability of geochemical tags may limit the accuracy of nursery origin determinations. Otolith elemental composition was used to assign a single cohort of 0-group sea bass Dicentrarchus labrax to their nursery estuary thus establishing an initial baseline for stocks in waters around Ireland. Using a standard LDFA model, high classification accuracies to nursery sites (80–88%) were obtained. Temporal stability of otolith geochemical tags was also investigated to assess if annual sampling is required for connectivity studies. Geochemical tag stability was found to be strongly estuary dependent.

Coast‐Wide Nursery Contribution of New Recruits to the Population of Atlantic Menhaden

AbstractThe Atlantic Menhaden Brevoortia tyrannus is a coastal‐spawning, estuarine‐dependent clupeid that has economic and environmental value along the U.S. East Coast. Atlantic Menhaden spawn offshore and rely on circulation patterns in the ocean to deliver larvae to multiple estuarine nursery grounds for juvenile development before recruiting to the adult stock. Historical estimates of the Atlantic Menhaden nursery contribution by each of the major nurseries along the coast indicate that the Chesapeake Bay produces 69% of the recruits to the adult stock; yet, these estimates are over 20 years old and have never been quantitatively validated. We used otolith chemistry for three cohorts of age‐1 Atlantic Menhaden to evaluate nursery contribution and provide updated recruitment rates for each of the nursery grounds for this species. Based on geochemical signatures and a quadratic discriminant function that assigned juveniles to their nursery grounds at nearly 90% accuracy, we classified age‐1 menhaden of unknown nursery origin collected coastwide. We found that for the 2009–2011 year‐classes, the contribution from Chesapeake Bay still dominates the proportion of age‐1 recruits, but this contribution has declined to between 16% and 65% of that earlier estimate. Nursery grounds in New England as well as those found south of Chesapeake Bay have become more significant contributors of age‐1 Atlantic Menhaden than previously expected.Received November 7, 2015; accepted January 26, 2016 Published online April 27, 2016

Otolith chemistry as an indicator of movements of albacore (Thunnus alalunga) in the North Atlantic Ocean

Albacore (Thunnus alalunga) in the North Atlantic Ocean is currently managed as a single well-mixed stock, although this assumption remains contentious. We measured stable isotopes (δ13C and δ18O) and trace elements (Mg, Mn, Sr, Ba) in otoliths of albacore collected from two feeding grounds, namely the Bay of Biscay and Atlantic offshore waters, and compared them among sampling locations and life history stages. Measurements in otolith core, post-core and edge were used to determine whether albacore from these two regions have the same nursery origin and migratory patterns. We found no clear evidence of distinct nursery grounds based on otolith core chemistry, but Sr:Ca and Mg:Ca were different in the post-core portions of albacore from the two locations, suggesting residency in different regions during the early juvenile stage. Otolith edge chemistry, particularly stable isotopes and Sr:Ca, proved to be a valuable tool for classifying individuals to their capture locations. Annual cycles of Sr:Ca ratios were visible along life history transects, likely reflecting migratory patterns between water masses of differing salinity, but the timing of Sr:Ca cycles differed between the two groups. Differentiation in trace element concentrations in the otolith post-core and the timing of Sr:Ca cycles suggest the occurrence of two migratory contingents of albacore in the north-east Atlantic Ocean.

Origin of Atlantic bluefin tuna (Thunnus thynnus) in the Bay of Biscay

Abstract We used carbon and oxygen isotope ratios (δ13C and δ18O) in otoliths as a tool for identifying the nursery origin of Atlantic bluefin tuna (Thunnus thynnus) caught in the eastern North Atlantic Ocean (Bay of Biscay). Juvenile and adult bluefin tuna were collected over three consecutive years (2009—2011) using the regional bait boat fleet. Otolith δ13C and δ18O values of bluefin tuna were measured by mass spectrometry, and values were compared with a reference sample of yearling bluefin tuna from eastern (Mediterranean Sea) and western (Gulf of Mexico) nurseries to determine nursery origin. Maximum likelihood estimates based on otolith δ13C and δ18O values indicated that the overall contribution of western migrants to the Bay of Biscay fishery was <1% and varied over the years assessed. A small number of potential western migrants (2.7%) was detected in 2009, and most of these fish appear members of the abundant 2002 and 2003 year classes. In contrast, the Bay of Biscay fishery was composed exclusively (100%) of eastern origin bluefin tuna in 2010 and 2011, suggesting that this fishery is supported almost exclusively by the eastern spawning area but transatlantic western population may contribute to this fishery in a few years.

Nursery origin of yellowfin tuna in the Hawaiian Islands

Stable isotopes of carbon (! 13 C) and oxygen (! 18 O) in otolith cores (first 2 mo of age) of young-of-the-year (YOY) yellowfin tuna Thunnus albacares were used as natural tracers to pre- dict the nursery origin of sub-adults (age-1) collected from the Hawaiian Islands. YOY fish were first collected from nurseries throughout the western and central Pacific Ocean (WCPO) to deter- mine whether ! 13 C and ! 18 O values of otolith cores (! 13 Cotolith and ! 18 Ootolith) were sufficiently dif- ferent to discriminate individuals from different nurseries used during the YOY period. Nurseries examined included both nearshore Hawaiian Islands and offshore Hawaiian Islands (Cross Seamount), and 4 locations in the equatorial Pacific Ocean: Line Islands, Marshall Islands, Solomon Islands, and Philippines. Significant differences existed in ! 13 Cotolith and ! 18 Ootolith among YOY yellowfin tuna from different nurseries for each year of the 2 yr study period (2008!2009). Individuals from the nearshore Hawaiian Islands were most enriched in ! 18 Ootolith, while samples obtained from the Philippines were most depleted in both ! 13 Cotolith and ! 18 Ootolith relative to other regions. Inter-annual variability in otolith core chemistry was minor and only observed for individ- uals collected from the Philippines. Overall classification success from quadratic discriminant function analysis of YOY yellowfin tuna to their respective nursery of collection was 63 and 87% for 2008 and 2009, respectively. Mixed-stock analysis indicated 91% of the sub-adult yellowfin tuna collected from the nearshore Hawaiian Islands originated from this same nursery. In addition, sub-adults from the offshore location within the Hawaiian Islands appear to originate from the nearshore Hawaiian Islands, highlighting the importance of local production and retention of yellowfin tuna to the standing stock and domestic fisheries of Hawaii.

Natal origin of Atlantic bluefin tuna (Thunnus thynnus) from Canadian waters based on otolith δ13C and δ18O

Increased knowledge of stock mixing and migration of Atlantic bluefin tuna ( Thunnus thynnus ) is required to properly manage and conserve declining populations. Here, we predicted the nursery origin of giant bluefin tuna (n = 224) present in samples from Canadian waters using stable δ13C and δ18O isotopes in otoliths. The isotopic composition of milled otolith cores (corresponding to the first year of life) of giant bluefin tuna from three decades (1970s, 1980s, 2000s) and three regions within or adjacent to the Gulf of St. Lawrence was compared with otolith δ13C and δ18O of yearling bluefin tuna collected from eastern (Mediterranean Sea – eastern Atlantic, n = 136) and western (western Atlantic, n = 103) nurseries. Maximum likelihood estimates indicated that greater than 99% of bluefin tuna in our Canadian samples originated from the western nursery. No significant differences in estimates of origin for bluefin tuna were detected among decades or among regions, suggesting little to no mixing of eastern and western populations in the Canadian samples examined. These findings justify the use of catch rates from the Gulf of St. Lawrence area as an index of abundance for the oldest members of the western population.

Evidence of estuarine nursery origin of five coastal fish species along the Portuguese coast through otolith elemental fingerprints

Connectivity is a critical property of marine populations, particularly for species with segregated juvenile and adult habitats. Knowledge of this link is fundamental in understanding population structure and dynamics. Young adults of commercially important fish species Solea solea, Solea senegalensis, Platichthys flesus, Diplodus vulgaris and Dicentrarchus labrax were sampled off the Portuguese coast in order to establish preliminary evidence of estuarine nursery origins through otolith elemental fingerprints. Concentrations of Li, Na, Mg, K, Mn, Cu, Zn, Sr, Ba and Pb in the otolith section corresponding to juvenile's nursery life period were determined through laser ablation inductively coupled plasma mass spectrometry. Element: Ca ratios in coastal fish differed significantly amongst collection areas, except for Platichthys flesus, and were compared with the elemental fingerprints previously defined for age 0 juveniles in the main estuarine nurseries of the Portuguese coast. Identification of nursery estuaries was achieved for four of the species. Assigned nursery origins varied amongst species and differences in the spatial scale of fish dispersal were also found. Diplodus vulgaris was not reliably assigned to any of the defined nurseries. Overall, results give evidence of the applicability of estuarine habitat tags in future assessments of estuarine nursery role. Research developments on the links between juvenile and adult habitats should contribute for the integrated management and conservation of nurseries and coastal stocks.

Reconstructing Habitat Use and Wetland Nursery Origin of Yellow Perch from Lake Superior using Otolith Elemental Analysis

The use of otolith elemental composition as a natural tag has emerged as a powerful tool for managing and understanding the ecology of marine fish populations. The approach remains relatively untested in fresh waters, so we examined its utility for reconstructing habitat use and wetland nursery origin in Lake Superior. We analyzed the otolith margin of adult yellow perch, Perca flavescens, as an indicator of recently occupied habitat, and the juvenile region of the otolith core as an indicator of nursery area. To characterize elemental fingerprints, all otolith samples were analyzed for Ca and 13 minor and trace elements using mass spectrometry. We found differences in the otolith concentrations of several elements between yellow perch inhabiting coastal wetlands and those inhabiting the adjacent nearshore waters of Chequamegon Bay. The most striking difference was the high concentration of Sr in the sagittal margins of wetland-caught fish relative to those captured in the bay. Based on differences in otolith Sr concentrations alone, fish from bay and wetland habitats could be distinguished with 100% accuracy. We also found that elemental fingerprints derived from otolith cores of adult yellow perch were similar among fish captured from wetlands adjacent to Chequamegon Bay but quite distinct for one site outside of the bay, suggesting these fish came from a separate population from those in Chequamegon Bay. Overall, these results encourage us that elemental fingerprinting techniques will be useful for estimating the relative importance of different coastal wetland habitats to wetland-dependent species in the Great Lakes.

Occurrence and etiology of death of young olive trees in southern Spain

New plantations of olive tree in southern Spain are being severely affected by wilt or dieback and death, which has been locally called ‘Drying Syndrome’. To determine the etiology of this problem, a study was carried out in samples of affected young trees collected during a seven year period (1989‐1995), and in two field surveys in 1994‐95 and 1996. Besides some insect damage and agronomic problems, the ‘Drying Syndrome’ was associated with Verticillium wilt, winter frost and root rot fungi. Although ‘Drying Syndrome’ can be distinguished from Verticillium wilt, the latter was included in this study, since, frequently, Verticillium wilt symptoms were unspecific and Verticillium dahliaecould not be always isolated in the diagnostic work that preceded this study. Early winter frost caused a vascular necrosis and wilt of the young olive trees. This unusual and severe damage was related with the lack of frost hardiness due to warm temperatures during the previous autumn. Root rot fungi were very frequent in the samples of diseased olive trees of field or nursery origin, and they were the main cause of ‘Drying Syndrome’ in the second field survey, when a heavy rainfall level occurred during winter. Pathogenicity tests showed that five fungal species ( Cylindrocarpon destructans, Phytophthora megasperma, P. palmivora, Pythium irregulare and Sclerotium rolfsii) were pathogenic to olive trees and reproduced symptoms of ‘Drying syndrome’ in rooted cuttings of cultivar Picual. Other fungal species associated with root rot of olive trees in the field or in the nurseries, including Fusarium acuminatum, F. eumartii, F. oxysporum, F. solani, Macrophomina phaseolina and Rhizoctonia solani, were weakly or not pathogenic. Pathogenicity of P. megasperma, P. palmivoraand P. irregulare depended on soil water content, since isolates tested caused extensive root rot and sudden plant death only when the soil was continuously waterlogged. The high frequency of P. megasperma in waterlogged field soils and its pathogenicity dependence on soil water content suggest that this pathogen may play an important role in the well known sensitivity of young olive trees to ‘root asphyxiation’. Abbreviations: DS ‐ drying syndrome of young olive trees; PHSC ‐ plant health service in C´ ordoba (Spain).

Pepper, Pickle, and Kipper

When we find an English word beginning with p, we quite properly suspect it of being an adopted word—if not evidently imitative or of nursery origin. For early English words beginning with p there are two chief sources: Latin (including indirectly Greek) and Celtic. If the word appears only in England, it may a priore have come from either of these languages. If it is found both in England and on the continent, it is almost sure to have come from the Latin. Pickle appears both in England and in North Germany, Holland, etc., and we are therefore justified in suspecting a Latin origin for it. It also belongs to the category of words that we know to have been largely drawn from Italy. In the earliest days the Italian traders introduced piper ‘pepper,’ vinum ‘wine,’ acetum ‘essig,’ etc. Later the Germanic peoples owed much of the development of the culinary art among them to the Christian priests and monks from Italy. They were fond of good living, of spices and of sauces. They brought with them from the South seeds and plants, and they raised vegetables and herbs for the table and for the cure of the sick. It is, therefore, but natural that we should suppose that so artificial a product as pickles should have had a similar source. These considerations and a knowledge of the South-German use of pfeffer in senses similar to those of pickle led me to associate pickle with pepper. One kind of pickling suggested that kipper was only another form of the same word.