Euphausiidae of the Coastal Northeast Pacific

Adult Euphausiidae of the Coastal Northeast Pacific

A Field Guide

Eric M. Keen

SIO 271 Marine Zooplankton Professor Mark Ohman Spring 2012

Note: “Euphausiid morphology” figure on inside cover was adapted from Baker et al. (1990) Table of Contents

How to Use this Guide...... i Introduction...... 1 Taxonomy & Morphology...... 1 Special Identification Techniques...... 4 Diversity...... 3 Distribution...... 5 Geographic extent...... 5 Bathymetric extent...... 6

Identification Keys Higher Taxon key...... 9 Generic key...... 10 Euphausia...... 15 Nematobrachion...... 18 Nematoscelis...... 19 Stylocheiron...... 20 Thysanoessa...... 21 Thysanopoda...... 24

Life History Notes Euphausia...... 28 Nematobrachion...... 30 Nematoscelis...... 31 Nyctophanes...... 32 Stylocheiron...... 33 Tessarabrachion...... 34 Thysanoessa...... 34 Thysanopoda...... 38

Append ix I: Species list of worldwide Euphausiids...... 41 Appendix II: Potential “vagrants”...... 42

Literature Cited...... 45 How to Use this Guide

The intent here was to create a quick-reference handbook for researchers at work in the coastal and nearshore waters of the Northeast Pacific (see map below). The species included here were chosen based upon range information in Kathman et al. (1986) and Brinton et al. (1999). This guide is for adult euphausiid forms only, defined by the presence of fully-developed secondary sexual characteristics and the capacity to reproduce. Including other life phases was beyond the scope of this project. To the knowledge of this author, no identification guide currently exists strictly for this region, at least not in field-ready paper form. Hopefully this will be of use for students with a range of resources available to them, from those with access to little more than a hand lens or dissecting microscope (like this author), as well as to those engaged in fully equipped studies on research-vessels. For those with computer access while in the field or during analysis of your collections, the CD-ROMEuphausiids of the World Ocean (Brinton et al. 1999) is the most up-to-date and authoritative reference for range information, identification keys, and relevant literature. The identification keys were constructed by distill- ing extant keys for worldwide euphausiids to only those species occurring in the Northeast Pacific and adjus-ting the artwork ac- cordingly. This simplified published keys to be more useful, expedient, and in- formative for students of the region’s biological oceanography. The images in this guide were adapted The “coastal Northeast Pacific”, the region of focus in this field from Baker et al. (1990). guide, is delineated in gray shading here.

The content is divided into 4 sections, arranged in the order that they will tend to be drawn upon: i) A broad, generalized higher-taxa identification key to distinguish euphausiids from look-alikes (decapods and mysids). ii) A generic key, to identify any euphausiid collected in the Northeast Pacific down to the genus level. iii) Specific keys, which will identify euphausiids of a known genus down to the species level. iv) Notes on the life histories of each species occurring in the Northeast Pacific, including references as entry points into the literature for more regarding that species.

The appendices provide cursory information on potentially “vagrant” species into the region of focus in this guide. i Introduction

The Euphausiidae is a family of pelagic shrimp-like crustaceans known more commonly as krill, from the Norwegian word “kril”, mean- ing young fry (Kathman et al. 1986). The etymology of the name “Eu- phausiidae” is a reference to the luminescence produced by large light organs, or photophores, on the bodies of euphausiid species (Baker et al. 1990).

Euphausiids are known to dominate coastal mid- to high-latitude zoo- planktonic communities, and the northeast Pacific is no exception. Considered a “pivotal taxon” of pelagic ecosystems (Todd et al. 1996), euphausiids comprise a major portion of the plankton biomass (Kath- man et al. 1986). Most euphausiids are omnivorous filter feeders (Todd et al. 1996), ingesting algae, plankton, and detritus (Kathman et al. 1986). Some abundant species (e.g., E. pacifica, T. inermis) can be ac- tively predaceous (Kathman et al. 1986).

Euphausiids serve as vertical and horizontal transporters and distrib- utors of organic matter, micro- and macro-nutrients (e.g. vitamin A), radioisotopes and heavy metals. The detritivorous species are thought to serve as important nutrient recyclers, mixing and ingesting sedi- ments and fecal pellets during vertical migrations (Kathman et al. 1986). This taxon is therefore quite relevant to most branches of oceanography.

Taxonomy & Morphology

Subphylum Crustacea Class Branchiopoda (e.g., cladocerans) Class Maxillopoda (e.g., ostracods, copepods, branchiurans) Class Malacostraca Subclass Eumalacostraca Superorder Peracarids (e.g., mysids, amphipods, etc.) Superorder Eucarida Order Decapoda (e.g., shrimp) Order Euphausiacea Family Bentheuphausiidae Family Euphausiidae

Malacostraca is the largest class of the Crustacea and includes all the shrimp-, prawn-, lobster-, and crab-like creatures. In most malacostracans, up to three anterior pairs of thoracic legs are modified as maxillipeds (Todd et al. 1996). Many malacostracans live on the seafloor and 1 only send up their larvae into the planktonic realm (Hardy 1956, p. 166); however, the Euphausiacea (subclass Eumalacostraca: superorder Eucarida), is entirely pelagic, and therein we find the family Eu- phausiidae.

The body plan of eucarids is composed of two main parts: the cephalothorax and a well-developed abdomen. The cephalothorax is covered dorsally and laterally by the carapace, and includes two pairs of bira- mous pre-oral antennae, movable stalked eyes, then mouthparts and thoracic limbs ventrally. The abdomen consists of six segments, each of which carrying a pair of alike pleopods (Baker et al. 1990). At the posterior of the abdomen is the “tail”, consisting of the central telson and two flanking uropods that can fan out to provide excellent propulsion.

Euphausiids superficially resemble shrimp within the other eumalacostracan orders Decapoda and Mysida. In fact, euphausiids had once been allied with mysids (O. Mysidacea) in the taxon Schizopoda (Kath- man et al. 1986). Today, they are known to be phylogenetically and morphologically distinct, and fall within different superorders of the Malacostraca (euphausiids are within the Eucarida, mysids are within the Peracarida, or “pouch shrimp”). Among the many differences one could point to, perhaps the most immediately obvious is the lack of exposed gills in decapods and mysids. The gills of the Euphausiacea, by contrast, are readily apparent (Baker et al. 1990). Furthermore, euphausiids are typically larger than mysids; the eucarid carapace is fused to the thoracic segments, while in mysids the posterior carapace can be lifted easily from the body; euphausiaceans boast ventral photophores on their thoracic limb bases and abdominal pleopods; finally, euphausiids do not have balancing organs (statocysts) in their uropods as mysids do (Todd et al. 1996). (See Higher Taxon key, page 9.)

Within the superorder Eucarida, euphausiaceans (krill) substantially differ from decapods (true shrimp, crabs, lobsters, etc.). Decapod gills are covered by the carapace; euphausiacean gills are exposed. Deca- pods lack photophores; euphausiaceans typically have 5 pairs of them. The first three thoracopod pairs in decapods are modified as feeding appendages, or maxillipeds, and their posterior 5 thoracopods are uni- ramous; in Euphausiacea, all 8 thoracopods are functionally natatory, although in some species the second or third may be elongate and rap- torial to aid in predation. Decapods also have statocysts, while euphausiaceans do not.

The order Euphausiacea contains two families: the Euphausiidae and the Bentheuphausiidae, a deep-sea group whose only representative has been included in this guide for the sake of completeness. 2 The Euphausiidae can be separated informally into two groups accord- ing to the general shape of the eyes: rounded or “bilobate” (constricted clearly into two distinguishable upper and lower lobes)(after Baker et al. 1990). The exception to this rule is Thysanoessa, in which both eye forms occur. The bilobed genera include: Tessarabrachion, Nematosce- lis, Nematobrachion, and Stylocheiron. The remaining genera all have rounded eyes.

Euphausiids (see inside cover) boast 8 pairs of thoracic limbs (thoracopods). In numbering them, the most anterior is counted first by con- vention. Thoracopod morphology can provide insight into the life history of euphausiids. In some predatory species, the reduced posterior thoracic legs may reflect an adaptive accommodation to that feeding mode (Nemoto 1966; Kathman et al. 1986). There is also a relationship in some species between the shape of a euphausiid’s eye and the form of its thoracic legs. Round-eyed species tend to have uniform thoracic leg lengths (except for the 7th and 8th thoracopods, which may be reduced), while bilobate species have one or two anterior pairs that are greatly elongated (Baker et al. 1990).

Abdominal segments 1 to 5 all carry a pair of pleopods used for swim- ming. The petasma (or copulatory organ) is the collective term for the various lobes, hooks, and processes that develop on the first pleopod of males, for use in reproduction.

Photophores (the namesake of the Euphausiidae) are present in all North Pacific euphausiids. Their placement on the abdomen and thoracic carapace is almost uniform throughout the family (with the ex- ceptions of Stylocheiron, whose photophore placement is diagnostic for the genus, and some Nematobrachion species).

Special Identification Techniques

Most right-handed workers tend to prefer working with the specimen’s rostrum pointed left (which is how most identification guides have drawn it, including this one).

If using dissecting microscopes, a combination of low-angle reflected and transmitted light is recommended. Dark-ground illumination is best for fresh specimens and for examining setae on the thoracopods (thoracic legs) of euphausiids.

Keep in mind that in preserved specimens, the petasma (copulatory organ) is rolled up and has to be spread out before the shape of its vari- 3 ous processes can be seen (Baker et al. 1990).

For some euphausiid genera, a “silvering” staining technique has been used for finding and observing the female reproducting organ, or thy- lecum, but it is not necessary for indentification in northeast Pacific euphausiids (only for identifying Euphausia gibba and the atlantica/ microps group of Nematoscelis)(Baker et al. 1990).

More detailed accounts of Euphausiid morphology can be found in: Sars (1885) Hansen (1910,1911,1912) Boden et al. (1955) Mauchline & Fisher (1969) Brinton (1975) Mauchline (1980) McWhinnie et al. (1981)

Diversity

86 species of euphausiids are found worldwide (Brinton et al. 1999). Of those, this author has counted that 58 of them occur north of the equator in the Pacific Ocean. Of these, 9 are technically endemic to the North Pacific (based upon range maps from Brinton et al. 1999). Two of these have ranges that are further restrcited: Nematoscelis lobata occurs only in western Phillipine waters, and Euphausia nana occurs only in waters south of Japan. The other 6 all occur in the coastal and nearshore waters, and are included in this guide.

Euphausiids endemic to the North Pacific: Euphausia nana (Brinton 1962) Euphausia pacifica (Hansen 1911) Nematoscelis difficilis(Hansen 1911) Nematoscelis lobata (Hansen 1916) Nyctiphanes simplex (Hansen 1911) Tessarabrachion oculatum (Hansen 1911) Thysanoessa inspinata (Nemoto 1963) Thysanoessa longipes (Brandt, 1851) Thysanoessa spinifera (Holmes, 1900)

In Southern California Bight and the waters directly offshore of Scripps Institution of Oceanography, 18 euphausiid species are known to occur, the most common of which in San Diego waters is Euphausia pacifica (Boden 1950).

In the proceeding identification key and life history notes, we focus on 4 22 species (in 8 genera) that occur in the coastal and nearshore waters of the Northeast Pacific, after Kathman et al. (1986) and Brinton et al. (1999).

Distribution

Geographic extent Euphausiids occur in all oceans. They are typically found in greater concentrations in inshore and shelf waters than in oceanic waters, as well as along frontal structures in the open ocean (Boden 1950). This pattern is exemplified by the dominance of species like T. spinifera along the British Columbian coast. In terms of species richness, euphausiids exhibit higher species diversity in boundary zones where there is either mixing between water masses or seasonal mixing (Pier- rot-Bults 1997, Reid et al. 1978). It is logical then, that subpolar waters and the eastern boundary of the North Pacific contain a multitude of euphausiids, both in terms of diversity and abundance.

Species are usually restricted in range within specific latitudinal zones, or are associated with certain ranges of temperature or salinity (Kathman et al. 1986). For example, Thysanoessa inermis has only been recorded between 43 and 63 degrees north in the Pacific;Euphau - sia pacificaonly occurs in waters warmer than 9.5 degrees Celsius. Be- cause euphausiids are small, easily susceptible to both advective and convective currents, and do not have stabilizing organs like statocysts, appropriate buoyancy is probably a critical component of their habitat suitability. A primary determinant of buoyancy is salinity, which can also impose physiological constraints on krill. The critical minimum salinity for migration and survival for euphausiids is thought to lie between 15 and 20 parts per thousand (Regan 1968; Gilfillian 1970). Species that occupy coastal inlets and fiords, such as Thysanoessa spinifera, must be tolerant of not only low salinities but also high variability in the salinity of their habitat on tidal, daily, and seasonal scales. The evolution of such tolerance, and the development of life histories structured around variable saline conditions, may be a driving factor behind the biogeography and radiation of euphausiid species. Concur- rently, the relatively stable conditions of offshore habitats, even along frontal zones or in upwelling cells, pose their own challenges that could have brought about the speciation of ancestral euphausiids.

Bathymetric Distribution Twelve of the 22 northeast coastal Pacific euphausiids inhabit the epipelagic marine environment, while 8 are mesopelagic and 4 are bathy- 5 pelagic (Kathman et al. 1986). One species, Thysanopoda acutifrons, is eurybathic (occuring at all depths), but prefers mesopelagic habitats or deeper. The larval stages for all euphausiids are usually confined to the upper 100m (Boden 1950). Below are vertical distributions of species included in this guide, after Kathman et al. (1986) and Brinton (1962):

Epipelagic: Euphausia gibboides E. mutica E. pacifica E. recurva Nematoscelis difficilis Thysanoessa gregaria T. inermis T. inspinata T. longipes T. raschii T. spinifera Thysanopoda acutifrons (occurs in all zones, to 4000 m.)

Mesopelagic: Nematobrachion boopis N. flexipes Nematoscelis tenella Stylocheiron longicorne S. maximum Tessarabrachion oculatum Thysanopoda orientalis

Bathypelagic: Bentheuphausia amblyops (family Bentheuphausiidae) Thysanopoda cornuta T. egregia

Most euphausiids practice diel vertical migrations (DVM), remaining at depth during the day, venturing into shallower waters in the dark of night, and returning to depth before daylight. Some Euphausia species travel 500m vertically one-way (1 km round-trip), with adults migrating further than immature stages (Kathman et al. 1986). The euphausiids that do not practice daily vertical migrations tend to be mesopelagic or bathypelagic species, e.g. Nematobrachion boopis, Stylocheiron longicorne, and Thysanopoda cornuta. However, there are even excep- tions to this exception: Thysanopoda orientalis is a mesopelagic species that does perform DVM (Kathman et al. 1986). Thysanopoda egregia is 6 a bathypelagic euphausiid who is thought to perform reverse vertical migrations (Mauchline 1980).

Often, species ranges correlate to oceanography. Euphausia superba is the dominant euphausiid of the Southern Ocean, whose circumpolar range is bound closely to the Antarctic Convergence, a frontal zone sur- rounding the Antartctic Circumpolar Current (Brinton et al. 1999), is a perfect example of this.

Focusing on the 6 northeast Pacific representatives of the genus Thy- sanoessa, we can see that their biogeography hints at their ecological roles, and vice versa. Thysanoessa is cosmopolitan in subtropical and subpolar waters, but generally does not occur within the tropics (Kath- man et al. 1986). Relative to other abundant north Pacific euhapusiid genera (Stylocheiron, Nematobrachion, and Euphausia), Thysanoessa is considered the most northerly, and dominates euphausiid assemblages in the mid- and high-latitudes (Boden 1950).

T. gregaria has a pan-Pacific subtropical distribution, confined to oli- gotrophic gyre waters by the North Equatorial Current to the south and the North Pacific Current to the north. Ranges of T. inspinata and T. longipes are latitudinally divided to the south and north, re- spectively, along the highy productive subarctic frontal zone, a major oceanographic boundary in the mid-latitude Pacific.T. inermis is more coastal and subarctic, spanning the Bering Strait and quite far-ranging in the Atlantic. It is known to occur much deeper than other coastal thysanoessans. T. raschii is a shallow-water, cold-adapted neritic species that occupies coastal habitats around the Arctic circle. Finally, T. spinifera is even more nearshore, restricted to upwelling zones of the northeast Pacific, from Alaska to Baja California. It is supposedly tolerant of much lower salinity than the others mentioned here. This brief review of Thysanoessa biogeography hints at the interplay of oceanography, ecological competition, and vertical niche space in driving euphausiid radiation. While competition is not limited to only those within the same genus (e.g., the highly abundant Euphausia pacifica is sympatric with T. spinifera), it does go to explain the differentiation of morphological and ecological adaptations among sister species.

Such patterns may be the cause and/or the result of the euphausiid’s evolutionary radiation. Diverging preferences for habitat and food come to enhance one another and further isolate sister taxa. As with most phylogeographic histories, we can expect ecological and environmental variability together structured the euphausiid evolutionary tree.

7 Identification Keys

8 Eumalacostracan Key Eumalacostracans

Higher Taxa Key

1a. Gills easily visible on thoracic segments, including segments 7 and 8. = Euphausiidae.

1b. Gills all hidden under the carapace, or, at most, visible only on last two segments. = Decapod or Peracarid (e.g. mysid).

Suggested references for mysid identification: Kathman et al. (1986)

9 Family EUPHAUSIIDAE

GENERIC KEY

1a. Photophores present on abdominal segments one to four, OR photophores not present at all on abdomen or thorax. (Except in the giant Thysanopoda, abdominal photophores are large, about 10% of the abdominal segment length, and are easily visible). = Go to 2.

1b. Photophores present only on abdominal segment 1. = Stylocheiron spp.

10 Generic Key 2a. Round eyes (or nearly round); thoracopods of approximately the same length. = Go to 3.

2b. Bilobate eyes (eyes in two parts with a constriction between the lobes); one or two pairs of thoracopods are greatly elongated. = Go to 6.

3a. A full complement of 8 thoracopods. = Bentheuphausia amblyops (of the Bentheuphausiidae). (Fresh specimens are a deep red and at first sight may be confused with bathypelagic decapods. Look for exposed gills. The eyes are small, oval, and have a small dorsal protu- berance. The main characters which distinguish the monospecific family are the 8 pairs of fully developed thoracopods, the absence of petasmae on the first pair of pleopods, and a transverse suture near the distal end of the outer ramus of the uropods.)

3b. Eighth thoracopod extremely minute. Seventh thoracopod smaller than the sixth, but the same shape and with the same number of segments. = Thysanopoda spp.

3c. Eigth thoracopod extremely minute and seventh with only two segments or reduced to a very small process. = Go to 4.

11 Generic Key

4a. A denticle at the mid-point or on the posterior half of the lateral margin of the carapace. An anterior lateral denticle also may be present. = Euphausia spp.

4b. There is either no lateral denticle, OR, if one is present, it is well anterior to the mid-point of the lateral margin of the carapace. =Go to 5.

12 Generic Key 5a. A strong recurved lappet on the first segment of antennular- pe duncle. = Nyctiphanes simplex.

5b. The lappet, if present, is small and not recurved. = Thysanoessa spp. (rounded eyes)

6a. Second and third thoracopod elongated. = Tessarabrachia oculatum. (These might be broken off during capture. However, if any legs were originally long, their bases will be obviously larger than those of the other legs.)

6b. Second thoracopod elongated. = Go to 7.

6c. Third thoracopod elongated. = Nematobrachion spp.

13 Generic Key 7a. Second thoracic legs very slender and naked with only a tuft of terminal bristles. Terminal segment of first thoracopod with short, robust comb-like spines. = Nematoscelis spp.

7b. Second thoracic legs strong, last two segments armed with spi- niform bristles. Terminal segment of first thoracopod hardly broader than penultimate segment and with only fine terminal setae. = Thysanoessa spp.

14 Specific Key: G. Euphausia Genus EUPHAUSIA

1a. Two pairs of lateral denticles on lower margins of carapace. = Go to 2.

1b. One pair of lateral denticles on lower margins of carapace. = Go to 3.

15 Specific Key: G. Euphausia 2a. Antennular lappet large, bifid, and erect in the female, and large, simple, and directed backwards in the male. Distal end of third segment of antennular peduncle with acute forward pointing tooth. = E. recurva.

2b. Antennular lappet small and pointing forwards. Only a low keel on distal end of third segment of antennular peduncle. = E. mutica.

16 Specific Key: G. Euphausia 3a. Spines mid-dorsally on third or third to fifth abdominal segments. = E. gibboides.

3b. No mid-dorsal spines on any segments. = E. pacifica.

17 Specific Key: G. Nematobrachion Genus NEMATOBRACHION

1a. Rostrum sharp, a lateral denticle on posterior-lateral margin of carapace and prominent mid-dorsal spines on abdominal segments three to five. =N. flexipes.

1b. Rostrum blunt, no lateral denticle on carapace and no mid-dorsal spines on any abdominal segments. = N. boöpis.

18 Specific Key: G. Nematoscelis Genus NEMATOSCELIS

1a. Carapace with a conspicuous dorsal keel. Propodus of first thoracopod with 3 rows of setae. = N. difficilis.

1b. Propodus of first thoracopod with two rows of setae. Lower part of eye much smaller than upper part. = N. tenella.

19 Specific Key: G. Stylocheiron Genus STYLOCHEIRON

1a. Antennal scale long and narrow, about 12 to 20 times longer than it is wide at its widest point. = S. longicorne.

1b. Antennal scale moderately broad, not more than 8 times longer than it is wide at its widest point. = S. maximum.

20 Specific Key: G. Thysanoessa Genus THYSANOESSA

1a. Bilobate eyes (with a clear transverse constriction between upper and lower lobes); 2nd thoracopod greatly elongated. = Go to 2.

1b. Round or almost-round eyes (with no clear tranverse constriction); 2nd thoracopod not appreciably elongated. = Go to 4.

2a. Lateral denticle is well posterior to mid-point of the margin of the carapace. = Go to 3.

2b. Lateral denticle at, or only just posterior to, mid-point of the margin of the carapace. = T. longipes.

21 Specific Key: G. Thysanoessa 3a. No mid-dorsal keels on any abdominal segments. = T. gregaria.

3b. Mid-dorsal keels present on third to fifth abdominal segments. = T. inspinata.

22 Specific Key: G. Thysanoessa 4a. A lateral denticle present anterior to mid-point of the margin of the carpace. = T. raschii.

4b. No lateral denticle on the margin of the carapace. = Go to 5.

5a. Strong dorsal keels on first to fifth abdominal segments; those on fourth and fifth segments end in spines. =T. spinifera.

5b. No dorsal keels or spines on 1st to 3rd abdominal segments. May bear a spine on posterior dorsal margin of sixth abdominal segment and there may be small spines (and extremely rarely, keels) on fourth and fifth abdominal segments. =T. inermis.

23 Specific Key: G. Thysanopoda Genus THYSANOPODA

1a. Carapace without distinct cervical groove; sixth abdominal segment longer than fifth. (If the joint between the 5th and 6th segments is flexed the thin arthrodial membrane joining them may be exposed. When comparing the lengths consider only the heaviliy chitinized exo- skeleton.) = Go to 2.

1b. Carapace has well-developed cervical groove; sixth abdominal segment same length or shorter than 5th. = Go to 3.

24 Specific Key: G. Thysanopoda 2a. Posterior margins of fourth and fifth abdominal segments very slightly pointed mid-dorsally. = T. orientalis.

2b. Posterior margins of fourth and fifth abdominal segments rounded. = T. acutifrons.

25 Specific Key: G. Thysanopoda 3a. Frontal plate curves slightly upwards anteriorly and ends in a small rostral process which points obliquely upwards. = T. cornuta.

3b. Frontal plate curves slightly downwards anteriorly. = T. egregia.

26 Life History Notes

27 Life History Notes Euphausia This is the largest genus of the euphausiids; 8 species are endemic to antarctic or subantarctic waters, although no species are found in the Arctic Ocean and only one, E. pacifica, in subarctic waters (Boden et al. 1955).&

Euphausia gibboides (Ortmann 1893) A mostly epipelagic euphausiid. This species is a temperate and subtropical species of the Atlantic and Pacific, between 30 degrees N and 40-45 degrees N (Brinton 1962). It occurs from 280m to 700m during the day and shallower at night. Larvae and juveniles are usually above 280m (Boden et al. 1955, Brin- ton 1962, Mauchline & Fisher 1969, Ponomareva 1963).

Euphausia mutica (Hansen 1905) This mostly epipelagic species occurs in the Atlantic, Pacific, and Indian Oceans. In the North Pacific it is more widely distributed (25-45 degrees N) than its most similar relative, E. recurva. It inhabits the same depths as E. recurva (140-700m in day, upper 100m at night), and the two species co-occur in the North Pacific Gyre (Brinton 1962, Mauchline & Fisher 1969). Here it is associated with the temperature range 16-25 degrees C at 100m depth. It occurs in the southeastern tropical Pacific as well. (10-30 degrees S).

28 Life History Notes E. pacifica (Hansen 1911) This epipelagic species is endemic to the North Pacific. Populations are densest in the North Pacific Drift, Aleutian Current and off southeast California in the California Current. It is the dominant euphausiid within 300-400 miles off the coast of Pt. Conception, California (Boden et al. 1955), and is very abundant northward to the Bering Sea (Banner 1950). Concentrations as high as 10,000/ m3 just above the oxycline at about 150m in Saanich inlet have been observed from submersibles (Mackie & Mills 1983). Banner (1950) and Fulton and LeB- rasseur (1984) found this species most common in the upper 300m during the spring in B.C. Distribution of this species in B.C. coastal waters is not limited by salinity and temperature except in shallow surface waters (Gilfillan 1970, Regan 1968). More rare to absent in the Bering Sea and Aleutian Islands’ waters.

E. pacificafeeds mostly at night; it is a filter feeder that consumes detritus and algae, but also predates upon chaetognaths, echinoderms and crustaceans (Mauchline & Fisher 1969). It is an important prey species for blue, fin, humpback and right whales, as well as squids, decapods, and birds (Mauchline 1980, Vermeer 1981, Vermeer 1985, Vermeer et al. 1985).

Off of Oregon, E. pacifica larvae are most abundant between October and De- cember, with no major concentrations during winter or spring (Smiles & Percy 1971). Individuals live about 1 year, although in some areas a second, non- breeding year has been observed (Ponomareva 1963, Heath 1977). Larvae have also been found from May to September in the Strait of Georgia and Saanich Inlet by (Heath 1977), which lends evidence to the hypothesis of a two-year life cycle.

29 Life History Notes Euphausia recurva (Hansen 1905) This epipelagic species occurs in Atlantic, Pacific, and Indian Oceans, with a similar N. Pacific distribution toE. mutica (with whom it co-occurs in the central North Pacific). It has an antitropical distribution, occurring between 40 and 20 degrees N, and between 20 and 40 degrees S. Not reported from British Columbia. It inhabits depths between 140m and 600m during the day and above 100m at night (Boden et al. 1955, Brinton 1975, Mauchline 1980). It is known to aggregate in patches and breeding swarms. E. recurva is a major food source for blue, fin, humpback, and sei and Bryde’s whales, as well as planktivorous fish (Mauchline 1980, Mauchline & Fisher 1969). It is detritivorous and predatorial, feeding upon detritus, tintinnids, radiolarians, and crustaceans (Mauchline 1980).

Nematobrachion boopis (Calman 1896) This is a mesopelagic species that does not perform vertical migrations. It occurs in Pacific, Atlantic, and Indian Oceans, and is widely distributed in the North and South Pacific south of 40-42 degrees North (Brinton 1962, Mauch- line & Fisher 1969). Adults are usually found below 400-500m, and larvae and immatures below 100m (Boden et al. 1955, Brinton 1962). In subarctic and subantarctic zones, it occurs in shallower waters (Brinton 1962). N. boopis is a predatory feeder and is consumed by planktivorous fish (Mauchline 1980).

30 Life History Notes Nematobrachion flexipes(Ortmann 1893) A lower epipelagic species. It is a rare but widespread species in the Pacific, but also occurs in the Atlantic and Indian Oceans. In the Pacific, N. flexipes generally occurs south of 40 degrees North, but has been found off Alaska and British Columbia (Fulton & LeBrasseur 1984). Adults live between 280 and 700m during the day, and above 280m at night. Larvae and immatures occur above 280m (Brinton 1962, Mauchline & Fisher 1969). N. flexipes is considered a predator, and is eaten by planktivorous fishes (Mauchline 1980).

Nematoscelis Eggs are carried externally by the female, attached to the thoracopods by a glu- tinous adhesive (Brinton 1975). Widespread in the Atlantic, Pacific and Indian Oceans, and the Mediterranean, East China, and South China Seas (Mauch- line & Fisher 1969). Nematoscelis difficilis(Hansen 1911) A shallow epipelagic species. N. difficilis is endemic to the North Pacific, found between 35 and 45 degrees N, but extends north into Queen Charlotte Sound and south to 20N in the California Current System (Mauchline & Fisher 1969). Banner (1950) found it as high as 51N, from Oregon to BC and in Queen Char- lotte Sound. It is a common species in west Canada’s coastal waters (Fulton & LeBrasseur 1984). It occurs regularly from 140m to 300m depths, occasionally as far as 50m above the thermocline where it exists. This species is an important food item for whales, fish, and birds (Mauchline 1980).

31 Life History Notes Nematoscelis tenella (G.O. Sars 1883) This mesopelagic species is widely distributed in Pacific, Atlantic, and Indi- an Oceans. In the Pacific it occurs south of 50 degrees N, primarily near the shelf. Warm water intrusions caused by El Nino events may push its range northward temporarily. Adults are generally found between 200m and 800m depths, while larvae are confined above 100m (Boden et al. 1955, Brinton 1962, Mauchline & Fisher 1969). N. tenella is an omnivore, consuming diatoms, dinoflagellates, radiolarians and crustaceans. It is eaten by planktivorous and micronektonic fish (Mauchline 1980).

Nyctiphanes simplex (Hansen 1911) A shallow epipelagic species, occurring in the North Pacific. It is normally found in Gulf of California and in the Peru Current, but has been recorded at higher latitudes (near Strait of Juan de Fuca) during ENSO-driven intrusions of warm water. N. simplex is associated with coastal waters in transition zones between warm and cold currents, often conspicuous in areas of upwelling (Brinton 1962). It performs daily vertical migration, and also aggregates. Found at 50-300m depths during the day and 0-100m at night (Mauchline 1980). N. simplex is consumed by both fish and whales.

32 Life History Notes Stylocheiron A warm water epipelagic genus (the 2 species local to San Diego are excep- tions). Widely distributed in Indian, Atlantic, and Pacific Oceans (Brinton 1962, Hansen 1912).

Stylocheiron longicorne (G.O. Sars 1883) This mesopelagic species occurs in the Pacific, Atlantic, and Indian Oceans. In the NE Pacific, it can be found as far north as British Columbia (Banner 1950, Fulton & LeBrasseur 1984). It can occur as shallow as 100-500m deep. It typically does not vertically migrate; if it does, it only goes short distanc- es (Mauchline 1980, Mauchline & Fisher 1969). This predatorial euphausiid feeds mainly upon crustaceans and algae. It is consumed by planktivorous and micronektonic fish (Mauchline 1980).

Stylocheiron maximum (Hansen 1980) This mesopelagic species is the largest in its genus (Brinton 1975). It occurs in the Pacific, Atlantic, and Indian Oceans (Mauchline & Fisher 1969). In the Pa- cific, it is present from the Aleutian Islands south to 50 degrees South, and it is fairly common in coastal British Columbia and Washington (Banner 1950, Ful- ton & LeBrasseur 1984). It is notably absent from the eastern tropical Pacific (Brinton 1962). Adults typically occur below 500m (Mauchline & Fisher 1969). S. maximum is a predator of crustaceans, detritus, and diatoms. It is preye upon by demersal and micronektonic fishes (Mauchline 1980).

33 Life History Notes Tessarabrachion oculatum (Hansen 1911) This mesopelagic species is endemic to the North Pacific (53 degrees N to 35 degrees N, from Sea of Japan to the California Current). It has also been found in the Bering Sea along the Aleutian Islands. Being a mesopelagic species, all bioluminescent organs are present (Hansen 1915). It can be caught as deep at 1000m (Fulton & LeBrasseur 1984, Mauchline & Fisher 1969). T. oculatum is an important prey for planktivorous fish (Mauchline 1980).

Thysanoessa

Thysanoessa is cosmopolitan in subtropical and subpolar waters, but generally does not occur within the tropics (Kathman et al. 1986). Relative to other abundant north Pacific euhapusiid genera (Stylocheiron, Nematobrachion, and Euphau- sia), Thysanoessa is considered the most northerly, and dominates euphausiid assemblages in the mid- and high-latitudes (Boden 1950). All Thysanoessa species are epipelagic, found at depths ranging from 0 to 1000m (Kathman et al. 1986). This adaptive ability to span a considerable depth range may be reflected in the bilobate eye of the genus (Kathman et al. 1986).

There are 10 species within the genus Thysanoessa, 6 of which occur in the North Pacific. Of this subset, 3 are endemic to the north PacificT. ( inspinata, T. longipes, and T. spinifera; Kathman et al. 1986).

Thysanoessa gregaria(G.O. Sars, 1883) A mostly epipelagic species. Occurs in the North and South Pacific, Middle and South Atlantic, and Indian Oceans. Reported consistently from only the temperate area of the North and South Atlantic and North and South Pacific in surface and deep waters. Allegedly common in tropical oceanic areas at depth, where the species may submerge along with sloping isotherms. On the western North American coast, it occurs from southern California to Oregon (Boden 1950, Boden et al. 1955). It is commonly found above 200m, but can occur as deep as 1000m (Boden et al. 1955; Nemoto 1966). T. gregaria is an offshore filter- feeding species; as an adult it can also be carnivorous, consuming detritus and dinoflagellates in particular (Mauchline 1980). This is possibly reflected in the short tough spines of the dactyl of the elongated thoracopod. Consumes detri-

34 Life History Notes tus and dinoflagellates. It is eaten by fin, humpback, sei, and Bryde’s whales, as well as planktivorous fish and birds (Mauchline & Fisher 1969).

Thysanoessa inermis(Kroyer, 1846) An epipelagic species. It has been reported from the North Atlantic, North Pacific, Arctic, Beaufort Sea, and the Svalbard Archipelago. In the Pacific this species occurs south of ~43 degrees N (Brinton 1962, Mauchline & Fisher 1969). Most occur between 140-280m during the day, and shallower night, but have been found as deep as 400m. Their habitat is restricted to 32.1-33.4 o/ oo salinity in the northern North Pacific (Fukuchi 1977). T. inermis is a predator; it feeds upon diatoms, dinoflagellates, tintinnids, radiolarians, medusa, chaetognaths, molluscs, echinoderms, and crustaceans, as well as detritus (Mauchline 1980, Mauchline & Fisher 1969). It is an important component of the diets of blue, fin, sei, and humpback whales, as well as seals, fish, and birds (Mauchline 1960, Mauchline & Fisher 1969). This species composed 90% of the diet for whales sampled in a study at the whaling station of Akutan, Alaska (Banner 1950).

35 Life History Notes Thysanoessa inspinata (Nemoto 1963) An epipelagic species. This species is endemic to the North Pacific, occurring south of 50 degrees N in the Gulf of Alaska and occurring as far west as the Sea of Japan. In the Queen Charlotte Islands region, it has been known to co- occur with T. longipes (Fulton & LeBrasseur 1984). It usually occurs in <300m of water. T. inspinata is a relatively important food items for blue, fin, sei, and humpback whales (Mauchline & Fisher 1969).

Thysanoessa longipes(Brandt, 1851) An epipelagic species. T. longipes is endemic to the North Pacific, and has been recorded from California to Alaska as well as in the Sea of Japan, Okhohtsk Sea and Bering Sea (Banner 1950, Fulton & LeBrasseur 1984). San Diego is the southernmost record (as of the 1950s) and the species seems to occur here only as an occasional straggler (Boden 1950). Usually inhabits depths ranging from 0 to 500m, and salinities ranging from 32.6-34.1 o/oo in the northern N. Pacific (Fukuchi 1977). In coastal B.C. inlets, it has been found in salinities of 24.5-27.2 o/oo (Regan 1968). T. longipes consumes detritus, diatoms, dinoflagellates, tintinnids, chaetognaths, echinoderms, and crustaceans (Mauchline 1980). It is an important food item for birds (Vermeer 1981,Vermeer 1985, Vermeer et al. 1985) and blue, fin, sei, and humpback whales (Mauchline 1980, Mauchline & Fisher 1969).

36 Life History Notes Thysanoessa raschii(M. Sars, 1864) An epipelagic euphausiid. This species occurs in the North Atlantic, North Pa- cific, and Arctic, including Svalbard. It has been recorded at higher latitudes, off Oregon, British Columbia, and Alaska, as well as the Clyde Sea near Brit- ain (Hardy 1956). It inhabits the continental shelf or the neritic shore waters in the Arctic regions (Nemoto 1966). It is a shallow epipelagic species, found from 0-200m. In the coastal inlets of B.C., it can be found in salinities of 25.7 – 26.8 o/oo (Regan 1968). T. raschii is filter-feeding omnivore, relying upon detritus, algae, diatoms, dinoflagellates, tintinnids, radiolarians, chaetognaths, and crustaceans.

Thysanoessa spinifera (Holmes, 1900) An epipelagic species. Endemic to the northeast Pacific, found from Baja Cali- fornia to GOA. Usually found in less than 100m of waters, but can live as deep as 300m (Mauchline & Fisher 1969, Nemoto 1966). T. spinifera is relatively uncommon in San Diego waters (Boden 1950). Typically occurs in a salinity range of 32.0-33.4 o/oo in the northern North Pacific. In fjords and inlets, where it is common, it can occur in salinities between 14.3 and 27.3 o/oo (Re- gan 1968). Growth rates and distributions have been studied for the January- April period for the B.C. coast by (Fulton & LeBrasseur 1984). T. spinifera and large copepod blooms coincide with the breeding of Cassin’s auklets at Tri- angle Island in the North Pacific (Vermeer 1981, Vermeer 1985, Vermeer et al. 1985). It is a dominant food item for baleen whales in the coastal waters of the eastern Aleutian Islands (Ponomareva 1963), for blue, fin, and humpback whales in the Gulf of Alaska (Mauchline & Fisher 1969), and for fish.

37 Life History Notes Thysanopoda Fourteen species are known, four of which have been found in the coastal northeast Pacific. Widespread throughout North & South Atlantic, Pacific and Indian Oceans. Thysanopoda acutifrons (Holt & Tattersall 1905) This epipelagic species is found in the Atlantic, Indian, and Pacific (North and South) Oceans. It is found along the coast from California to Alaska. Large numbers off British Columbia have been found from January to March (Boden et al. 1955). It occurs at depths of 0-700m, vertically migrating to less than 200m depth at night (Mauchline & Fisher 1969). T. acutifrons adults prefer a temperature range of 3-6 degrees C, while larvae prefer 4-10 degrees C (Ein- arsson 1945). This species eats diatoms and crustaceans, and is eaten by planktivorous whales and fish (Mauchline & Fisher 1969).

Thysanopoda cornuta (Illig 1905) This wide-ranging bathypelagic species occurs from Gulf of Alaska to Califor- nia in the North Pacfic (Mauchline 1980). This species does not perform vertical migrations (Mauchline 1980). Adults occur below 2000m, immatures near 100m or deeper, and larvae can be found 700m to 2000m in depth (Brinton 1952). It inhabits waters colder than 2 or 3 degrees C. Its habitat preferences might be correlated with nearby seamounts, islands, and continental slopes seaward of 3000m (Brinton 1962). It is a fast swimmer, often able to escape sampling nets. T. cornuta is mainly predatorial, consuming diatoms, radiolarians, medusa, chaetognaths, crustaceans, and fish (Mauchline 1980).

38 Life History Notes Thysanopoda egregia(Hansen 1905) This is a large bathypelagic euphausiid. Adults inhabit depths greater than 2000m, in waters colder than 2-3 degrees C (Brinton 1962). Although it is considered a rare species, this may be an artifact of the scarcity and difficul- ty of bathypelagic sampling; they are also fast swimmers, able to avoid nets (Brinton 1962). Larvae have been found in greater numbers nearer the surface during the day, suggesting a reverse vertical migration (Brinton 1962); others posit that this species does not vertically migrate (e.g. Mauchline 1980). T. egregia is mainly predatorial, consuming detritus, radiolarians, chaetognaths, molluscs, crustaceans, and fish (Mauchline 1980).

Thysanopoda orientalis (Hansen 1910) This mesopelagic species is found in all oceans, usually below 400m depth between latitudes 40 degrees North and South (Mauchline & Fisher 1969). In the North Pacific, they are rarely observed north of California (Kathman et al. 1986). Larvae are known to occur above 200m. Adults are known to perform daily vertical migrations (Mauchline & Fisher 1969). This species, a predator of crustaceans, is eaten by planktivorous fish (Mauchline 1980). Range below is in lined grey.

39 Male & female Euphausia pacifica, from Brinton et al. (1999).

40 Appendix I: List of Worldwide Euphausiids

Bentheuphausia amblyops G.O. Sars, 1885 Nyctiphanes couchi Bell, 1853 Nyctiphanes simplex Hansen, 1911 Euphausia americana Hansen, 1911 Euphausia brevis Hansen, 1905 Pseudeuphausia latifrons G.O. Sars, 1883 Euphausia crystallorophias Holt & Tatter Pseudeuphausia sinica Wang & Chen, sall, 1906 1963 Euphausia diomedeae Ortmann, 1894 Euphausia distinguenda Hansen, 1911 Stylocheiron abbreviatum G.O. Sars, 1883 Euphausia sibogae Hansen, 1908 Stylocheiron affine Hansen, 1910 Euphausia eximia Hansen, 1911 Stylocheiron armatum Colosi, 1917 Euphausia fallax Hansen, 1916 Stylocheiron carinatum G.O. Sars, 1883 Euphausia frigida Hansen, 1911 Stylocheiron elongatum G.O. Sars, 1883 Euphausia gibba G.O. Sars, 1883) Stylocheiron indicum Silas & Mathew, Euphausia gibboides Ortmann, 1893 1967 Euphausia hanseni Zimmer, 1915 Stylocheiron insulare Hansen, 1910 Euphausia hemigibba Hansen, 1910 Stylocheiron longicorne G.O. Sars, 1883 Euphausia krohni (Brandt, 1851) Stylocheiron maximum Hansen, 1908 Euphausia lamelligera Hansen, 1911 Stylocheiron microphthalma Hansen, 1910 Euphausia longirostris Hansen, 1908 Stylocheiron robustum Brinton, 1962 Euphausia lucens Hansen, 1905 Stylocheiron suhmi G.O. Sars, 1883 Euphausia mucronata G.O.Sars, 1883 Euphausia mutica Hansen, 1905 Tessarabrachion oculatum Hansen, 1911 Euphausia nana Brinton, 1962 Euphausia pacifica Hansen, 1911 Thysanoessa gregaria G.O. Sars, 1883 Euphausia paragibba Hansen, 1910 Thysanoessa inermis Krøyer, 1846 Euphausia pseudogibba Ortmann, 1893 Thysanoessa inspinata Nemoto, 1963 Euphausia recurva Hansen, 1905 Thysanoessa longicaudata Krøyer, 1846 Euphausia sanzoi Torelli, 1934 Thysanoessa longipes Brandt, 1851 Euphausia sibogae Hansen, 1908 Thysanoessa macrura G.O. Sars, 1883 Euphausia similis G.O. Sars, 1883 Thysanoessa parva Hansen, 1905 Euphausia similis variety armata Thysanoessa raschii M. Sars, 1864 Euphausia spinifera G.O. Sars, 1883 Thysanoessa spinifera Holmes, 1900 Euphausia superba Dana, 1850 Thysanoessa vicina Hansen, 1911 Euphausia tenera Hansen, 1905 Euphausia triacantha Holt and Tattersall, Thysanopoda acutifrons Holt & Tattersall, 1906 1905 Euphausia vallentini Stebbing, 1900 Thysanopoda aequalis Hansen, 1905 Thysanopoda astylata Brinton, 1975 Meganyctiphanes norvegica M. Sars, 1857 Thysanopoda cornuta Illig, 1905 Thysanopoda cristata G.O. Sars, 1883 Nematobrachion boopis Calman, 1896 Thysanopoda egregia Hansen, 1905 Nematocrachion flexipes Ortmann, 1893 Thysanopoda microphthalma G.O. Sars, Nematobrachion sexspinosum Hansen, 1911 1885 Thysanopoda minyops Brinton, 1987 Nematoscelis atlantica Hansen, 1910 Thysanopoda monacantha Ortmann, 1893 Nematoscelis difficilis Hansen, 1911 Thysanopoda obtusifrons G.O. Sars, 1883 Nematoscelis gracilis Hansen, 1910 Thysanopoda orientalis Hansen, 1910 Nematoscelis lobata Hansen, 1916 Thysanopoda pectinata Ortmann, 1893 Nematoscelis megalops G. O. Sars, 1883 Thysanopoda spinicaudata Brinton, 1953 Nematoscelis microps G.O. Sars, 1883 Thysanopoda tricuspidata Milne-Edwards, Nematoscelis tenella G.O. Sars, 1883 1837

Nyctiphanes australis G. O. Sars, 1883 Nyctiphanes capensis Hansen, 1911 After Brinton et al. (1999). 41 Appendix II: Potential “Vagrants”

Below are known distributions for euphausiid species that are known to occur in the North Pacific and will possibly be encountered in the regional focus of this guide, the coastal Northeast Pacific. Interannual climatic oscillations and longer- term climate change might affect the distributions of species reported in cpub- lished resources; should a species be encountered that does not fit into the identification keys provided above, these species are the most likely contenders for what you have found. Range maps provided here are from Brinton et al. (1999).

42 Appendix II: Potential Vagrants

43 Appendix II: Potential Vagrants

Literature Cited

Baker, A. de C., D.P. Boden, & E. Brinton. 1990. A practical guide to the Euphausiids of the World. British Museum (Natural History): London, Great Britain. Banner, A.H. 1950. The Mysidacea and Euphausiacea. Pages 447-448 in Gulf og Mexico, its origin, waters, and marine life. Fisheries Bulletin 89. Fish. Wildl. Serv., Washington. Boden, B.P. 1950. The crustaceans of the order Euphausiacea from the temperate northeast Pacific, with notes on their biology. Dissertation. UC: Los Angeles. Boden, B.P., M.W. Johnson, and E. Brinton. 1955. The Euphausiacea (Crustacea) of the North Pacific.Bulletin of Scripps Institution of Oceanography 6:287-400. Brinton, E. 1962. Variable factors affecting apparent range and estimated concentration of euphausiids in the North Pacific.Pacific Science 16:374-408. Brinton, E. 1975. Euphausiids of Southeast Asian waters. Naga Report. Scientific Re- sults of Marine Investigations of the South China Sea and the Gulf of Thailand. 4(5):1- 287. Brinton, E., M.D. Ohman, A.W. Townsend, M.D. Knight, and A.L. Bridgeman. 1999. Euphausiids of the World Ocean. World Diversity Database CD-ROM Series. Windows Version 1.0. ETI Expert Center for Taxonomic Identification: Mauritskade, Netherlands. Einarsson, H. 1945. Euphausiaea. I. North Atlantic species. Dana Report. Copenhagen 27:1-191. Fukuchi, M. 1977. Regional distribution of Amphipoda and Euphausiacea in the northern North Pacific and Bering Sea in summer of 1969. Res. Inst. N. Pac. Fish. Contr. No. 95:439-458. Fulton, J., and R. LeBrasseur. 1984. Euphausiids of the continental shelf and slope of the Pacific coast of Canada.La Mer 22:268-276. Gilfillian, E.S. 1970. The effects of changes in temperatue, salinity and undefined properties ofsea water on the respiration of Euphausia pacifica Hansen (Crustacea) in rela- tion to the species’ ecology. Ph.D. Thesis, University of British Columbia. 126 p. Hardy, A.C. 1956. The New Naturalist: A Survey of British Natural History. The Open Sea – Its Natural History: The World of Plankton. Eds. Fishers, James, John Gilmour, Julian Huxley, L. Dudley Stamp. Hansen, H.J. 1910. The Schizopoda of the Siboga Expedition. Siboga-Expedite. Leiden 37:1-123. Hansen, H.J. 1911. The genera and species of the order Euphausiacea, with account of remarkable variation. Bulletin de l’Institut Oceanographique de Monaco No. 210:1-54. Hansen, H.J. 1912. Report on the scientific results of the expedition to the eastern tropical Pacific, in charge of Alexander Agassiz, by the U.S. Fish Commission steamer “Alba- tross”, from Otcober 1904 to March 1905, Lieut-Commander L.M. Garrett, U.S.N. com- manding. XXVI and XXVII. The Schizopoda. Memoirs of the Museum of Comparative Zoology, at Harvard College. 35:175-296. Hansen, H.J. 1915. The Crustacea Euphausiacea of the United States Museum. Proceed- ings of the United States National Museum. 48:59-114. Heath, W.A. 1977. The ecology of harvesting of euphausiids in the Strait of Georgia. Ph.D. thesis, University of British Columbia. 187 p.

45 Kathman, R.D., W.C. Austin, J.C. Saltman, and J.D. Fulton. 1986. Identification Manual to the Mysidacea and Euphausiacea of the Northeast Pacific.Canadian Special Publica- tion of Fisheries and Aquatic Sciences 93. Mackie, G.O. and C.E. Mills. 1983. Use of the Pices IV submersible for zooplankton studies in coastal waters of British Columbia. Canadian Journal of Fisheries and Aquatic Sciences 40:763-776. Mauchline, J., and L.R. Fisher. 1969. The biology of Euphausiids. Advanced Marine Biol- ogy 7:1-454. Mauchline, J. 1980. The biology of mysids and euphausiids. Advanced Marine Biology 18:1-681. McWhinnie, M.A.m C.J. Denys, and P.V. Angione. 1981. Euphausiacea Bibliography: a world literature survey. Pergamon Press: USA. Nemoto, T. 1966. Thysanoessa euphausiids, comparative morphology, allomorphosis, and ecology. Sci. Rep. Whales. Res. Inst. Tokyo 20:109-155. Pierrot-Bults, A.C. 1997. Biological diversity in oceanic macrozooplankton: more than counting species. In Marine Biodiversity: Patterns & Processes. Eds. Ormond, Rupert F.G., John D. Gage, & Martin V. Angel. Cambridge University Press: Cambridge, UK. Ponomareva, L.A. 1963. The euphausiids of the North Pacific, their distribution and ecology. Dok. Akad. Nauk SSSR:1-142. Transl. from Russian by Israel Programme for Science Translation, Jerusalem, 1966. Regan, L. 1968. Euphausia pacific and other euphausiids in the coastal watrs of B.C.: relationships to temperature, salinity, and other properties in the field and laboratory. Ph.D. Thesis, University of British Columbia. 274 p. Reid, J., E. Brinton, A. Fleminger, E.L. Venrick, and J.A. McGowan. 1978. Ocean circula- tion and marine life. In Advances in Oceanography, ed. H. Charnock & Sir G. Deacon, pp. 65-130. New York: Plenum Press. Sars, G.O. 1885. Report on the Schizopoda collected by H.M.S. Challenger during the years 1873-1876. Report on the Scientific Results of the Voyage of the H.M.S. Challenger, 1873-1876. London. Zoology 13:1-228. Smiles M.G. Jr. and W.G. Pearcy. 1971. Size structure and growth rate of Euphausia pacifica off the Oregon coast.U.S. Fisheries Bulletin 69:79-86. Todd, C.D., M.S. Laverack, and G.A. Boxhall. 1996. Coastal Marine Zooplankton: a practical manual for students. 2nd edition. Cambridge University Press: Over Wallop, Hampshire, UK. p. 54 Vermeer, K. 1981. The importance of plankton to Cassin’s auklets during breeding. Journal of Plankton Research 3:315-329. Vermeer, K. 1985. The diet and food consumption of nestling Cassin’s auklets during summer, and a comparison with other plankton-feeding alcids. Murrelet 65:65-77. Vermeer, K., J.D. Fulton, and S.G. Sealy. 1985. Differential use of zooplankton prey by ancient murrelets and Cassin’s auklets in the Queen Charlotte Islands. Journal of Plankton Research 7:443-459.

46 Euphausiids of the coastal Northeast Pacific

Based on Kathman et al. (1986) (n=22)

Euphausia gibboides, Ortmann 1893 E. mutica, Hansen 1905 E. pacifica, Hansen 1911 E. recurva, Hansen 1905

Nematobrachion boopis, Calman 1905 N. fllexipes, Ortmann 1893

Nematoscelis tenella, G.O. Sars 1883 N. difficilis Hansen 1911

Nyctiphanes simplex, Hansen 1908

Stylocheiron longicorne, G.O. Sars 1883 S. maximum, Hansen 1908

Tessarabrachion oculatum, Hansen 1911

Thysanoessa gregaria, G.O. Sars 1883 T. inermis, Kroyer 1846 T. inspinata, Nemoto 1963 T. longipes, Brandt 1851 T. raschii, M. Sars 1864 T. spinifera, Holmes 1900

Thysanopoda acutifrons, Holt and Tattersall 1905 T. cornuta, Illig 1905 T. egregia, Hansen 1905 T. orientalis, Hansen 1910

Also: Bentheuphausia amblyops (of f. Bentheuphausiidae)