The Making of a Productivity Hotspot in the Coastal Ocean

Highly productive hotspots in the ocean often occur where complex physical forcing mechanisms lead to aggregation of primary and secondary producers. Understanding how hotspots persist, however, requires combining knowledge of the spatio-temporal linkages between geomorphology, physical forcing, and biological responses with the physiological requirements and movement of top predators.) off the Baja California peninsula, Mexico.We have identified the set of conditions that lead to a persistent top predator hotspot, which increases our understanding of how highly migratory species exploit productive regions of the ocean. These results will aid in the development of spatially and environmentally explicit management strategies for marine species of conservation concern

The state of California current, 2001 – 2002 : will the Californa current system keep its cool, or is El Niño coming?

This report summarizes physical and biological conditions in the California Current System (CCS), from Oregon to Baja California, in 2001 and 2002. The principal sources of the observations described here are the CalCOFI (California Cooperative Oceanic Fisheries Investigations), IMECOCAL (Investigaciones Mexicanas de la Corriente de California), and U.S. GLOBECLTOP (Global Ecosystems Long-term Observation Program) programs. Large-scale atmospheric and oceanic conditions in the Pacific point to a fourth consecutive La Niña-like year. This has contributed to generally stronger than normal upwelling and uncharacteristically cool waters in much of the CCS, a pattern that has persisted since late 1998. Biological productivity has been generally higher as well, particularly off Oregon. Within the observed interannual fluctuations of recent years, these conditions suggest a generally elevated production off California and Oregon, but cool conditions have led to lower than normal zooplankton biomass off Baja California. Although the tropical Pacific has exhibited some indications of a developing El Niño, it is not likely to impact the CCS during the productive upwelling season of 2002. These observations are continuing evidence that a regime shift may have occurred in 1998, resulting in substantial change in ecosystem structure in the CCS. Continued monitoring and analysis of the state of the CCS in this context is needed. We outline a plan for an integrated monitoring program for the entire region, through the creation of ACCEO (Alliance for California Current Ecosystem Observation)

Hyperiid amphipods from the Gulf of Ulloa and offshore region, Baja California: The possible role of the gelatinous zooplankton as a transport vector into the coastal shelf waters.

Hyperiid amphipod species from the Gulf of Ulloa, Baja California, and the adjacent region (from the shelf break to 200 km offshore) were analyzed to evaluate diversity and abundances. This productive area supports small-scale commercial fisheries, including sand bass (Paralabrax nebulifer), California spiny lobster (Panulirus interruptus), abalones, clams, and others. Strong coastal upwelling events were observed during summer seasons of the period 2002-2008 between Punta Eugenia and Punta Abreojos. The upwelling plumes at Punta Abreojos are transported southward in slope waters bordering the coastal shelf of the Gulf of Ulloa, contributing to the separation of coastal and oceanic regions, and explain differences in amphipod diversity and abundances between both regions. In the offshore region, the most abundant species were Vibilia armata, Lestrigonus schizogeneios, Primno brevidens, and Eupronoe minuta, similar to previous findings in northern regions of Baja California and southern California. However, abundances of these species were lower (10-30 individuals/1000 m3), only reaching 20-50% of abundance levels reported off northern Baja California. In the coastal shelf of the Gulf of Ulloa, amphipods were virtually absent during 2002, 2003 and 2006. However, during 2004 and 2005, abundances of P. brevidens increased (54 and 20 ind/1000 m3, respectively). Moreover, during the late summer of 2007, abundances of L. schizogeneios, P. brevidens, Lycaea nasuta, Lycaea pulex, and Simorhynchotus antennarius increased considerably (261, 39, 31, 68, 416 ind/1000 m3, respectively), indicating occasional utilization of the coastal shelf by pelagic amphipods. Changes in gelatinous populations (medusae, siphonophores, ctenophores, doliolids, and salps) paralleled changes in hyperiid populations, with highest abundances in 2005-2008 in the coastal shelf. Significant correlations of 17 amphipod species with gelatinous taxa, which are often used as host organisms by hyperiid amphipods, suggest that gelatinous presence enhanced hyperiid abundance and promoted the progression of hyperiid amphipods onto the coastal shelf during parts of the 2002-2008 period

Zooplankton of the Gulf of California after the 1982-1983 El Nino Event: Biomass Distribution and Abundance

From 23 March to 7 April 1984, we studied the responses of zooplankton populations to the 1982-1983 El Nino event in the Gulf of California. Twenty six stations were sampled for zooplankton distribution and abundance. Mean displacement volume was 388 cm3/lOOO m3 , a value higher than biomass values reported for the California Current and the eastern tropical Pacific. Maximum values (up to 60 mg/m3 of dry weight) were registered on the eastern shore of the gulf. At other stations biomass values ranged from 11.2 to 39.2 mg/m3 . No significant differences were observed in the mean biomass of the central gulf between spring 1983 and spring 1984. However, biomass increased in the southern gulf during spring 1984. Mean total abundance of zooplankton was 13% higher than in 1983. Coastal stations registered up to 31% of the total abundance. Copepods and cladocerans represented over 65% of mean total abundance and community structure differed from that in 1983: there were more copepods, euphausiids, tunicates, and siphonophores in 1984, and fewer cladocerans, ostracods, and red crabs (Pleuroncodes planipes). Similarity analysis showed two main assemblages: one in the central gulf (temperate zone), the other near the mouth (tropical zone). These two regions correspond to zones with different physical and primary production characteristics. The different responses seen in the central and southern gulf may reflect phytoplankton biomass and primary productivity dynamics. The El Nino event reduced the biomass in the southern part of the gulf, although the entire gulf in 1983 and 1984 showed higher biomass values than other eastern Pacific systems. Year-to-year differences may be less important than seasonal changes. The EI Nino phenomenon mainly affected the relative abundances of different taxa

Spatial and temporal occurrence of fin whales (Balaenoptera physalus) and euphausiids (Nyctiphanes simplex) in the Ballenas Channel, Gulf of California, Mexico

Fin whales (Balaenoptera physalus) are observed year-round in the Ballenas Channel and Bahía de los Ángeles region, Gulf of California, where their main food item is the euphausiid Nyctiphanes simplex. This investigation was designed under the hypothesis that the spatial and temporal occurrence of whales and euphausiids coincides. The aim was to establish the geographic, seasonal, and interannual changes in the abundance of the fin whale and its main prey in the region during 2003 and 2004. Four field trips were carried out per year. Surveys to search for whales and carry out horizontal surface tows were conducted from small boats. Fin whales and euphausiids were mainly observed off the coast of Baja California and in the southern Ballenas Channel. Their abundance varied significantly from one season to another in both years. The highest relative abundance of whales occurred in July (warm season), followed by June (cold–warm transition period) and March–April (cold season), and the lowest in October (late warm season). Euphausiid abundance was significantly higher in June (cold–warm transition period), followed by July (warm season). There was no direct correlation between weekly abundances of both species, probably because whale peak abundance occurred four weeks later than euphausiid peak abundance. Fin whale relative abundance was significantly higher in 2004 than in 2003 (2.22 and 0.46 whales h–1, respectively), but euphausiid abundance remained almost the same (geometric means 255 and 174 ind/1000 m3). Even though there was no weekly correlation between both species, their geographic distribution did overlap.

Multi‐decadal variations in calcareous holozooplankton in the California Current System: Thecosome pteropods, heteropods, and foraminifera

We examine long-term (1951-2008) variability of three major taxa of calcareous holozooplankton (aragonitesecreting thecosome pteropods and heteropods, and calcitesecreting large planktonic foraminifera) in light of recent interest in the impingement of waters undersarurated with respect to aragonite onto continental shelf depths in the California Current System. We assess interannual variability in springtime abundances of zooplankton sampled in the epipelagic layer, using CalCOFI (California Cooperative Oceanic Fisheries Investigations) zooplankton samples from two regions: Southern California (SC) and Central California (CC). Thecosome pteropods show no evidence of recent declines in abundance in SC or CC waters. In SC, sampling was sufficient to conclude that heteropods and large foraminifera also show no evidence of declines in abundance in recent years. These results do not preclude asyet undetected changes in vertical distributions or shell morphology, and underscore the importance of sustained in situ measurement programs in order to detect and understand changes to pelagic ecosystems. Copyright 2009 by the American Geophysical Union

Breeding biology, chick growth, and diet of the Least Storm-Petrel Oceanodroma microsoma on Islas San Benito, Mexico

Bedolla-Guzmán Y, Masello J, Aguirre-Muñoz A, Lavaniegos BE, Quillfeldt P. Breeding biology, chick growth, and diet of the Least Storm-Petrel Oceanodroma microsoma on Islas San Benito, Mexico. Marine Ornithology. 2017;45(2):129-138.The Least Storm-Petrel Oceanodroma microsoma is endemic to islands on both coasts of Baja California, in Mexico. It is the smallest seabird species and one of the least studied of the order Procellariiformes. We present a detailed account of its breeding success, chick growth, and diet at Islas San Benito, Baja California, during three consecutive breeding seasons (2013 to 2015) and of sex differences in adult morphology, a study conducted in 2012. Eggs hatched between late July and mid-September, and the fledging period started in mid-October. The timing of breeding varied from year to year: the hatching period began earlier in 2013 than in 2015 and was longer in 2014, while the fledging period started later in 2014 than in 2013. Hatching success (around 80%) and fledging success (about 90%) were consistently high in all three years. Nevertheless, nestlings fledged with longer wings, tails, and bills in 2015. Four species of euphausiids, two species of larval fish, and one species of squid were identified in food samples. Differences in the timing of breeding and chick growth during the period of this study may reflect a variation in food supply associated with anomalous climate conditions recorded in 2014 and 2015

Long-term Changes of Zooplankton Volumes in the California Current System. The Baja California Region.

A retrospeciive anaiysis oi zooplankton volumes (1951 to 1996) was performed for the area between Punta Baja (30°N) and Punta Abreojos (26 ?ON) in relatlon to the warming anomaly that has taken place in the California Current System during the last 2 decades. The seasonal cycle of median standing stock of zooplankton In this area showed a moderate alternation between h~ghva lues from June to October (median monthly volumes between 86 and 108 m1/1000 m") and low values from Kovember to May (58 to 77 m1/1000 m3). The quarterly long-term means of zooplankton volumes were the lowest in winter, as were wind speeds. The standard deviations associated with the long-term means indicated interannual variability was higher than seasonal variability. The time series showed an interval of high zooplankton volume between 1952 and 1957. Following the strong ENSO (El Nifio Southern Oscillation) of 1957-1958, a period of low values occurred which extended into the early 1960s. There was a slow recovery of zooplankton biomass through the rest of the 1960s, but it did not reach the earlier high values. Available data suggest the increasing trend reached a peak in 1975. Subsequently, from 1976 to the ENSO of 1982-1983, the biomass decreased. For the remainder of the 1980s, the few existing data showed an erratic behavior of the biomass. In the 1990s, there has been a decrease to values even lower than those observed durlng the 1957-1958 ENSO. Nonseasonal anomalles for zoop1.ankton and environmental variables were significantly different (p < 0.001) anlong decades but not between the northern (30" to 28" N) and southern (28" to 26" N) areas. The decrease in zooplankton volume in this region over the last 2 decades is less than that reported for the Southern California Bight. This may be partly caused by seasonal northward movements of tropical zooplancton species along the Baja California coast, Mexico