New records of benthic marine algae and Cyanobacteria for Costa Rica,and a comparison with other Central American countries

We present the results of an intensive sampling program carried out from 2000 to 2007 along both coasts of Costa Rica, Central America. The presence of 44 species of benthic marine algae is reported for the first time for Costa Rica. Most of the new records are Rhodophyta (27 spp.), followed by Chlorophyta (15 spp.), and Heterokontophyta, Phaeophycea (2 spp.). Overall, the currently known marine flora of Costa Rica is comprised of 446 benthic marine algae and 24 Cyanobacteria. This species number is an under estimation, and will increase when species of benthic marine algae from taxonomic groups where only limited information is available (e.g., microfilamentous benthic marine algae, Cyanobacteria) are included. The Caribbean coast harbors considerably more benthic marine algae (318 spp.) than the Pacific coast (190 spp.); such a trend has been observed in all neighboring countries. Compared to other Central American countries, Costa Rica has the highest number of reported benthic marine algae; however, Panama may have a similarly high diversity after unpublished results from a Rhodophyta survey (Wysor, unpublished) are included. Sixty-two species have been found along both the Pacific and Caribbean coasts of Costa Rica; we discuss this result in relation to the emergence of the Central American Isthmus.     

Species Distribution Models of Tropical Deep-Sea Snappers

Deep-sea fisheries provide an important source of protein to Pacific Island countries and territories that are highly dependent on fish for food security. However, spatial management of these deep-sea habitats is hindered by insufficient data. We developed species distribution models using spatially limited presence data for the main harvested species in the Western Central Pacific Ocean. We used bathymetric and water temperature data to develop presence-only species distribution models for the commercially exploited deep-sea snappers Etelis Cuvier 1828, Pristipomoides Valenciennes 1830, and Aphareus Cuvier 1830. We evaluated the performance of four different algorithms (CTA, GLM, MARS, and MAXENT) within the BIOMOD framework to obtain an ensemble of predicted distributions. We projected these predictions across the Western Central Pacific Ocean to produce maps of potential deep-sea snapper distributions in 32 countries and territories. Depth was consistently the best predictor of presence for all species groups across all models. Bathymetric slope was consistently the poorest predictor. Temperature at depth was a good predictor of presence for GLM only. Model precision was highest for MAXENT and CTA. There were strong regional patterns in predicted distribution of suitable habitat, with the largest areas of suitable habitat (> 35% of the Exclusive Economic Zone) predicted in seven South Pacific countries and territories (Fiji, Matthew & Hunter, Nauru, New Caledonia, Tonga, Vanuatu and Wallis & Futuna). Predicted habitat also varied among species, with the proportion of predicted habitat highest for Aphareus and lowest for Etelis. Despite data paucity, the relationship between deep-sea snapper presence and their environments was sufficiently strong to predict their distribution across a large area of the Pacific Ocean. Our results therefore provide a strong baseline for designing monitoring programs that balance resource exploitation and conservation planning, and for predicting future distributions of deep-sea snappers.     

Evaluation and application of methods for biological assessment of streams: summary of papers

The false mussel Mytilopsis adamsi, originally described from the Pacific coast of Panama, is reported for the first time as an introduced species in the Urías estuary and an adjacent shrimp farm, on the Pacific coasts of Mexico. In the 19th century, this species was transported from the Pacific coast of Panama, reaching the Indo-Pacific Ocean, but it had not been previously reported in other coasts of the American Pacific. Its recent and irregular presence in this small estuary near shore the Mazatlán harbor and an adjacent shrimp farm suggests that the species was introduced into the area but it cannot still be considered as a harmful invader. The presence of the species in the shrimp farm may indicate that it was introduced along with shrimp stocks from Central America, although its passive transportation to the estuary via ballast water or attached to hulls is not discounted.     

The presence of chlorophyll b and the estimation of phaeopigments in marine phytoplankton

A reverse-phase h.p.l.c. technique was used to estimate theconcentration of chlorophyll b in phytoplankton cultures, fecalpellets of Calanus pacificus, and suspended paniculate matterfrom the Central North Pacific, Oregon coastal waters, and DabobBay (a temperate fjord in Puget Sound, WA, USA). The purposewas to assess the distribution of this pigment in the euphoticzone and its effect on the fluorometnc estimation of phaeopigments.Analyses of natural waters confirm high chlorophyll b concentrations(median mass ratio of b:a > 0.3) at the depth of the chlorophylla maximum in tropical waters while values for temperate planktonare relatively low (median mass ratio of chl b:a = 0.05) andpatchy. Zooplankton fecal pellets showed a significant enrichmentin chlorophyll b, suggesting grazing as a mechanism to explainhigh concentrations of this pigment at the bottom of the euphoticzone. It is estimated that the presence of chlorophyll b couldcause an average overestimation of phaeopigment concentrationby the fluorometnc technique of 38% between 0 and 200 m in theCentral North Pacific. This effect is more pronounced at thelayer of chlorophyll b maximum (120–140 m). ¹Present address: Marine Biology Research Division, A-002, ScrippsInstitution of Oceanography, La Jolla, CA 92093, USA     

ELECTRON MICROSCOPY OF NANOPLANKTON FROM THE NORTH PACIFIC CENTRAL GYRE1

Nanoplankton was collected from the North Pacific Central Gyre during a cruise of R/V “Melville” in August 1985. Water samples from the surface and the deep chlorophyll maximum layer were fixed with glutaraldehyde and prepared for electron microscopy observation using formvar coated grids. The grids were examined first by epifluoresence microscopy under blue light to differentiate chloroplast and non-chloroplast containing cells. The surface and deep samples were dominated strongly by members of the Prymnesiophyceae, accounting for 55% of the total number of organisms identified. Prymnesiales and Coccosphaerales were equally abundant although coccoliths-bearing cells tended to dominate in the deep chlorophyll maximum layer. Heterotrophic choanoflagellates were also abundant at depth and were characterized by a high species diversity. Micromonas pusilla (Butcher) Manton & Parke was the major representative of the Prasinophyceae and was observed commonly within the deep chlorophyll maximum. Our observations reveal several new species, including autotrophic and heterotrophic specimens, and demonstrate the importance of knowing the structure of the planktonic community for ecological purposes. Indeed, the presence of a large number of heterotrophic organisms in the deep water suggests an active microbial food chain which may play an important role in regulating plankton processes in oligotrophic waters.     

Vertical distribution of pelagic chaetognaths and feeding of Sagitta enflata in the Central Equatorial Pacific

The vertical distribution and feeding of pelagic chaetognathsat 5°S, 160°W in the Central Equatorial Pacific wereinvestigated using a series of 0–500 m vertical haulswith a VMPS net over a 24 h period between 6 and 7 October 1990.The total number of individuals per haul was between 370 and688. Fourteen species in four genera were found at this station.The most abundant species was Sagitta enflata which comprised32.4–61.1% of the individuals collected from the 0–500m layer. Mesopelagic species made up 9.3–15.1% of thetotal number of individuals. Sagitta enflata and Pterosagittadraco were found in the upper part of the thermocline both byday and at night. The fraction of the population containingfood items (FCF) of S.enflata in the 0–50 m layer variedbetween 4.8 and 12.5% (mean 10.8%) and feeding activity washighest between sunrise and noon. The percentages of Copepoda,Foraminifera, crustacean larvae, Chaetognatha, Pteropoda, Ostracoda,fish and unidentified material in the gut of S.enflata were51.9,6.7,3.8,2.9,1.9,1.9 and 30.9%, respectively. Sagitta enflataconsumed food organisms which were mainly between 0.5 and 1.0mm in length. The daily feeding rate of S.enflata was 1.81 preyper individual, which was equivalent to 8.06 mg C m^–2day^–1. This corresponded to     

Phytogeography of the trees of the Osa Peninsula,Costa Rica

A phytogeographic analysis of the distributions of 454 species of trees native to the Osa Peninsula in 22 families revealed that 4.8% of the species are endemic to the Osa Peninsula and the adjacent mainland of Costa Rica. However, nearly one-fourth of the species might be regionally endemic to Central-South Mesoamerica (Costa Rica, Nicaragua, and Panama). Our sample suggests that 53.6% of the species occur in some part of Mesoamerica and sometimes range into northwestern South America, and that 44.5% of the species have wide distributions throughout tropical America. There is a strong affinity with the flora of northwestern South America, with 46.2% of the species on the Osa also found there. In addition, 50.6% of the tree species on the Osa occur on both the Atlantic and Pacific slopes of Central America or, if they reach South America, are sometimes found on both sides of the Andes. Major contributions to the tree flora of the Osa have been made by species arriving in the Osa by 1) dispersal from South and North America to islands in proto Central America before the formation of a dry-land connection between the two continents, and 2) migration from South America and North America after the closure of the Panamanian isthmus was made. This analysis demonstrates the importance of the Osa as a regional refuge for protecting species with distributions limited to the Osa and parts of Panama, Costa Rica, or Nicaragua. The Osa is also important because it harbors the last expanse of tropical wet forest on the Pacific slope of Central America large enough to ensure the survival of the Central American populations of widely distributed plants and animals.     

Adaptive evolution of sperm bindin tracks egg incompatibility in neotropical sea urchins of the genus Echinometra

Bindin is a gamete recognition protein known to control species-specificsperm-egg adhesion and membrane fusion in sea urchins. Previousanalyses have shown that diversifying selection on bindin aminoacid sequence is found when gametically incompatible speciesare compared, but not when species are compatible. The presentstudy analyzes bindin polymorphism and divergence in the threeclosely related species of Echinometra in Central America: E.lucunter and E. viridis from the Caribbean, and E. vanbruntifrom the eastern Pacific. The eggs of E. lucunter have evolveda strong block to fertilization by sperm of its neotropicalcongeners, whereas those of the other two species have not.As in the Indo-West Pacific (IWP) Echinometra, the neotropicalspecies show high intraspecific bindin polymorphism in the samegene regions as in the IWP species. Maximum likelihood analysisshows that many of the polymorphic codon sites are under mildpositive selection. Of the fixed amino acid replacements, mosthave accumulated along the bindin lineage of E. lucunter. Weanalyzed the data with maximum likelihood models of variationin positive selection across lineages and codon sites, and withmodels that consider sites and lineages simultaneously. Ourresults show that positive selection is concentrated along theE. lucunter bindin lineage, and that codon sites with aminoacid replacements fixed in this species show by far the highestsignal of positive selection. Lineage-specific positive selectionparalleling egg incompatibility provides support that adaptiveevolution of sperm proteins acts to maintain recognition ofbindin by changing egg receptors. Because both egg incompatibilityand bindin divergence are greater between allopatric speciesthan between sympatric species, the hypothesis of selectionagainst hybridization (reinforcement) cannot explain why adaptiveevolution has been confined to a single lineage in the AmericanEchinometra. Instead, processes acting to varying degrees withinspecies (e.g., sperm competition, sexual selection, and sexualconflict) are more promising explanations for lineage-specificpositive selection on bindin.     

POPULATION CHARACTERISTICS AND FOOD RESOURCE UTILIZATION OF CONUS IN THE SEA OF CORTEZ AND WEST MEXICO

The diets and population characteristics of three abundant speciesof Conns, nux, diadema and princeps, from the Sea of Cortezare described. All were found to feed predominantly upon polychaeteworms. In addition, food notes are presented for six less abundantspecies from the same area. Comparison of the diversity of thediets of the three dominant species in the Sea of Cortez withcognate species in the Indo-West Pacific, where significantlymore congeneric species occur in any single habitat, indicatedno significant increases in diversity of prey. This lack ofecological release with respect to food in the presence of fewercompeting congeners was attributed to the presence of significantlyfewer prey species when compared to the Indo-West Pacific. (Received 23 March 1978;     

PHYLOGENY AND BIOGEOGRAPHY OF THE ATLANTIC AND EASTERN PACIFIC HYPSELODORIS STIMPSON, 1855 (NUDIBRANCHIA, CHROMODORIDIDAE) WITH THE DESCRIPTION OF A NEW SPECIES FROM THE CARIBBEAN SEA

A new species, based on two specimens from Guana Island, BritishVirgin Islands, is described. The new species agrees with thegenus Hypselodoris in having a high body profile, a large vestibulargland and mantle glands. It differs from other members of thegenus in the Atlantic Ocean by having a reddish background bodycolour. In addition, dorsal colour patterns such as a broadcentral white line with lateral extensions and the lack of yellowlines or spots further differentiate this species. The radularformula of 52x41.0.41 and a smaller seminal receptacle are alsodistinctive. The phylogenetic relationships of 34 species andsubspecies of Hypselodoris from the eastern Pacific and Atlanticare examined using morphological characters. With the exceptionof the new species, these are characterized by a dark blue backgroundbody colour. The phylogenetic analysis of the data matrix resultedin eight most-parsimonious trees. The resulting consensus treeshows that eastern Pacific and Atlantic species of Hypselodorisconstitute a monophyletic group that is basally split into twosister clades. One clade contains the eastern Pacific speciesand most of the Caribbean species, whereas the other clade containsthe eastern Atlantic species. The new species is the sisterto the rest of the Caribbean species, which also form a monophyleticgroup. This phylogenetic hypothesis suggests that two consecutivevicariant events have affected the biogeography of Hypselodoris:(1) the closure of communication between the tropical Indo-Pacificregion and the Atlantic and eastern Pacific, completed withthe formation of the East Pacific Barrier; and (2) the riseof the Panama isthmus. (Received 19 December 2003; accepted 12 October 2005)     

Repartition des Appendiculaires au large des cotes de Californie

Twenty-seven taxa of appendicularians have been identified fromthe cruise CALCOFI n° 7202 and their distribution has beenstudied by various numerical methods, with the purpose of definingsimultaneously the groups of associated species and the groupsof stations possessing similar characteristics. Two large recurrentgroups have been defined by the method of Fager and McGowan,corresponding approximatively to the major water masses present:central Pacific waters and equatorial Pacific waters. The methodof Williams and Lambert permits the separation of 11 southernstations and a northern group divided into 2 subgroups dependingon the presence or absence of O. dioica. The rank correlationsgive results very similar to those obtained with point correlations.Finally, principal component analysis allow good separationof the northern and southern zones by the factorial plan 1–3,while representation of the stations by the factorial plan 2–3separates the two northern subgroups depending on the presenceor absence of O. dioica. The results obtained by the differentmethods are therefore very much alike, but it is difficult toconclude they are a result of the specific cruise, or whetherthey represent a general phenomenon.     

The vertical distributions of chlorophyll and phytoplankton species in the North Pacific central environment

The phytoplankton species in the North Pacific central environmentare known to be distributed into two vertically distinct assemblagesduring most of the year. Key species are defined for each assemblage.The vertical distributions of these key species indicate thatthe increase in abundance of deep species closely parallelsthe increase in chlorophyll a at the top of the chlorophyllmaximum layer. The chlorophyll maximum is comprised of speciescharacteristic of the deep assemblage, with only insignificantnumbers of shallow species.     

The Use of Bacteriological Variables for the Characterization of Different Water Bodies

Studies on the Mediterranean Undercurrent in the Gulf of Cádiz showed that bacterial abundance and biomass as well as heterotrophic activity were higher in the water of Mediterranean origin in 500–800 m depth than in the adjacent Atlantic water. Upwelling processes off Mauretania and Portugal were accompanied by high bacterial numbers (bacterial plate counts) in the mixed surface layer. Changes in the qualitative composition of the bacterial flora in the waters off West Africa and in the Arabian Gulf were explained by the introduction of dust from desert regions into the sea by aeolian transport. In the Western Baltic migration of fish was detected by the presence of special bacteria, which normally live on or in these animals. Regions with complex hydrographic structures such as the Western and Central Baltic Sea revealed interesting relationships between bacteriological abundance and activity on the one hand and characteristic physical and chemical properties, such as origin, salinity and O₂/H₂S-content, on the other. The importance of bacteriological variables for the characterization of different water bodies is discussed.     

PHYLOGENY OF THE GENUS ROSTANGA (NUDIBRANCHIA), WITH DESCRIPTIONS OF THREE NEW SPECIES FROM SOUTH AFRICA

Rostanga elandsia sp. nov., Rostanga aureamala sp. nov. andRostanga phepha sp. nov. are characterized by having the radulawith slender innermost lateral teeth, which lack denticles onthe inner side of the cusp and have a single denticle on theouter side. The outermost lateral teeth of these three speciesare elongate, but shorter than in other species of the genus.In addition, R. aureamala is the only species of the genus withrachidian teeth and R. phepha is unique within the genus Rostanga byvirtue of its white coloration with dark spots. A phylogenetic analysis shows that the three new species fromSouth Africa and Rostanga setidens (Odhner, 1939) are the sistergroup of the rest of the genus. The species from Japan and MarshallIslands (North Pacific Ocean) are basal in the sister cladecontaining the other species of Rostanga Bergh, 1879. The tropicalIndo-Pacific species of Rostanga are not monophyletic. The Atlanticand Eastern Pacific species form a monophyletic, derived clade,being the sister group of Rostanga australis Rudman & Avern,1989, which has a narrow range restricted to south eastern Australia.The widespread Indo-Pacific species Rostanga bifurcata Rudman& Avern, 1989, is the sister group of Rostanga dentacus Rudman& Avern, 1989, also widesprad in the tropical western Pacific. This phylogeny suggest s a viariant origin of the Sourth African, Atlantic-EasternPacific, and probably North Pacific species, whereas in thetropical Indo-Pacific most sister speceis are sympatric. (Received 16 May 1999; accepted 31 July 2000)     

Biotic Assemblages and Ecological Controls on Reefs and Banks of the Northwest Gulf of Mexico

This paper summarizes the results of investigations of the ecologyof reefs and banks in the northwestern Gulf of Mexico. Nearshoresurface waters are turbid out to approximately the 10 m isobath.A turbid nepheloid layer up to 20 m in thickness exists beyondthis depth. Seasonal temperature and salinity variability ishigh in nearshore waters. At the shelf edge, the temperatureto 50 m depth remains above 19°C. Topographic prominencesare common in the region. Most are surface expressions of thediapirism of underlying salt domes derived from deeply buriedJurassic salt deposits. Biotic zonation on the banks is primarilydepth related. Zones of major reef-building include the Diploria-Montastrea-Porites Zone (15–36 m), the Madracis Zone (28–46m), the Stephanocoenia-Millepora Zone (36–52 m), and theAlgal-Sponge Zone (45–98 m). A zone of minor reefbuildingon some banks is the Millepora Zone (18–52 m). An AntipatharianTransitional Zone exists from 56 to over 100 m on some banks.The Nepheloid Zone near the base of the banks is a zone of noreef-building. Not all zones are present on all banks. The communitystructure and depths of these zones depend on and are modifiedby the regional current regime, depth of the bank crests, substratecharacteristics, winter temperature minima, river influences,and the relative depth and thickness of the nepheloid layer.Nearshore communities are warm temperate in nature, though tropicalorganisms are occasionally abundant. Progressing offshore, thebenthos becomes increasingly tropical. The northerly locationand isolated nature of the Flower Gardens have lead to reducedcommunity diversity (e.g., only 18 of the 55 Western Atlantichermatypic coral species exist), but not reduced abundancesor growth rates of the species present. Assemblages on otherbanks exist below the tolerance limits of thriving tropicalreefs due to their frequent immersion in turbid water, excessivecrest depths, or lower minimum winter temperatures.     

Appendicularian assemblages in a shelf area and their relationship with temperature

The structure of the community of appendicularians was describedby multivariate analyses throughout a seasonal cycle on thecentral Cantabrian coast. It is shown by correlation and principalcomponents analysis that the appendicularian species may bearranged in a successional sequence in relative abundance thatis closely coupled to a temperature gradient. This sequencestarts with Fritillaria borealis, which exhibits highest relativeabundance during January, being sequentially followed by Oikopleuradioica, Fritillaria pellucida, Oikopleura fusiformis and Oikopleuralongicauda. This species numerically dominated the communityfrom September to December. Sea surface temperature and thetemperature at the depth of the chlorophyll maximum were bothreliable predictors of the species composition of the community.However, only the latter provided an adequate explanation forthe persistence of cryophilic communities in stratified oceanicenvironments and the dominance of thermophilic communities afterthe autumn mixing period. Under stratified conditions, surfacetemperatures are high (up to 21°C), but temperatures atthe depth of the chlorophyll maximum are low (<15°C).These differences disappear after the autumn mixing, when thewater column exhibits a uniform temperature profile (16°C).Critically, however, although there is a sharp decline in surfacetemperature, water at the depth of the chlorophyll maximum iswarmer than during stratification. A simple conceptual modelis proposed to account for these features and predictions aremade regarding the vertical distribution of appendiculariansduring stratification. The relevance of non-anthropomorphictemperature measures, such as the temperature at the depth ofthe chlorophyll maximum, for other zooplankton groups is alsodiscussed.     

Summer dynamics of the deep chlorophyll maximum in Lake Tahoe

Vertical profiles of chlorophyll and phytoplankton biomass weremeasured in Lake Tahoe from July 1976 through April 1977. Adeep chlorophyll maximum (DCM) persisted during summer and earlyautumn (July—October) near 100 m, well below the mixedlayer and at the upper surface of the nitracline. The DCM coincidedwith the phytoplankton biomass maximum as determined from cellcounts. In addition, the composition of the phytoplankton assemblagewas highly differentiated with respect to depth. Cyclotellastelligera was the predominant species in the mixed layer whilethe major species in the DCM layer included C. ocellata andseveral green ultraplanktonic species. In situ cell growth playsa substantial role in maintaining the DCM, but sinking of cellsfrom shallower depths and zooplankton grazing above the DCMmay contribute to the maintenance of the DCM. Calculations supportthe interpretation that the summer DCM persists at the boundarybetween an upper, nutrient-limited phytoplankton assemblageand a deeper, light-limited assemblage.     

华中地区藤本种子植物区系的研究

以湖南和湖北两省为代表对华中地区藤本种子植物的区系进行了研究。本区共有藤本种子植物62科175属838种,其中土著种类有60科159属784种。在科、属、种的水平上对藤本种子植物区系特性进行了较深入的统计和分析,并对本区藤本种子植物与邻近地区的关系、本区内的藤本种子植物的地带性分异进行了探讨。统计表明,本区藤本种子植物种数占该区种子植物总种数的11%,且61.7%的种类主要集中在30种以上的大科中;热带分布型明显多于温带分布型;泛热带、热带亚洲、东亚（中国）特有和东亚—北美间断分布科属比较集中,其中许多属为古老成分;本区藤本种子植物特有成分丰富,计有东亚特有科1科、中国特有属6属、中国特有种507种（其中华中地区特有种35种）。通过研究认为：本区藤本种子植物具有种类丰富、分布类型多样、特有成分较多、区系较古老的特点;与本区的全部种子植物区系相比,藤本种子植物区系的热带性更强,具有明显的热带亲缘性,并与喜马拉雅及中国西南有较强的地理渊源。     

Spatio-temporal distribution and production of calanoid copepods in the central Baltic Sea

The aim of our study was the exploration of species-specificdistribution and production patterns of dominant copepods inthe Central Baltic Sea (Bornholm Basin). Spatio-temporal distribution,egg and secondary production were studied by means of net-samplingand egg production experiments from April to August 1999. Verticaland horizontal distribution patterns appeared to be linked witheach other and were primarily species-dependent. Both Acartiaspp. and Temora longicornis preferentially inhabited the upper30 m of the water column and the shallower marginal regionsof the Bornholm Basin. In contrast, the C4–5 and C6 ofPseudocalanus spp. preferentially inhabited the halocline region(50–70 m) and the deep central part of the area. Observeddifferences in horizontal distribution among these three copepodsappear to result from different depth preferences and depth-dependentwater circulation patterns. Egg production rates (EPR) clearlyexhibited seasonal differences with maximum EPR in May and minimumEPR in July. Mean EPR was significantly different between species,being highest in Acartia spp. and lowest in Pseudocalanus spp.The variability in EPR was related to differences in hydrographyand modelled food environment.